[-next,V7,6/7] samples: ftrace: Add riscv support for SAMPLE_FTRACE_DIRECT[_MULTI]

  From: Song Shuai <suagrfillet@gmail.com>

select HAVE_SAMPLE_FTRACE_DIRECT and HAVE_SAMPLE_FTRACE_DIRECT_MULTI
for ARCH_RV64I in arch/riscv/Kconfig. And add riscv asm code for
the ftrace-direct*.c files in samples/ftrace/.

Signed-off-by: Song Shuai <suagrfillet@gmail.com>
Tested-by: Guo Ren <guoren@kernel.org>
Signed-off-by: Guo Ren <guoren@kernel.org>
---
 arch/riscv/Kconfig                          |  2 ++
 samples/ftrace/ftrace-direct-modify.c       | 33 ++++++++++++++++++
 samples/ftrace/ftrace-direct-multi-modify.c | 37 +++++++++++++++++++++
 samples/ftrace/ftrace-direct-multi.c        | 22 ++++++++++++
 samples/ftrace/ftrace-direct-too.c          | 26 +++++++++++++++
 samples/ftrace/ftrace-direct.c              | 22 ++++++++++++
 6 files changed, 142 insertions(+)
  

Hi,

On 12.01.2023 12:06, guoren@kernel.org wrote:
> From: Song Shuai <suagrfillet@gmail.com>
> 
> select HAVE_SAMPLE_FTRACE_DIRECT and HAVE_SAMPLE_FTRACE_DIRECT_MULTI
> for ARCH_RV64I in arch/riscv/Kconfig. And add riscv asm code for
> the ftrace-direct*.c files in samples/ftrace/.
> 
> Signed-off-by: Song Shuai <suagrfillet@gmail.com>
> Tested-by: Guo Ren <guoren@kernel.org>
> Signed-off-by: Guo Ren <guoren@kernel.org>
> ---
>   arch/riscv/Kconfig                          |  2 ++
>   samples/ftrace/ftrace-direct-modify.c       | 33 ++++++++++++++++++
>   samples/ftrace/ftrace-direct-multi-modify.c | 37 +++++++++++++++++++++
>   samples/ftrace/ftrace-direct-multi.c        | 22 ++++++++++++
>   samples/ftrace/ftrace-direct-too.c          | 26 +++++++++++++++
>   samples/ftrace/ftrace-direct.c              | 22 ++++++++++++
>   6 files changed, 142 insertions(+)

The samples were built OK now, but ftrace-direct-multi and 
ftrace-direct-multi-modify report incorrect values of ip/pc it seems.

I ran 'insmod ftrace-direct-multi.ko', waited a little and then checked 
the messages in the trace:

#           TASK-PID     CPU#  |||||  TIMESTAMP  FUNCTION
#              | |         |   |||||     |         |
      migration/1-19      [001] .....  3858.532131: my_direct_func1: my 
direct func1 ip 0
      migration/0-15      [000] d.s2.  3858.532136: my_direct_func1: my 
direct func1 ip ff60000001ba9600
      migration/0-15      [000] d..2.  3858.532204: my_direct_func1: my 
direct func1 ip ff60000003334d00
      migration/0-15      [000] .....  3858.532232: my_direct_func1: my 
direct func1 ip 0
        rcu_sched-14      [001] .....  3858.532257: my_direct_func1: my 
direct func1 ip 0
           insmod-415     [000] .....  3858.532270: my_direct_func1: my 
direct func1 ip 7fffffffffffffff
           <idle>-0       [001] ..s1.  3858.539051: my_direct_func1: my 
direct func1 ip ff60000001ba9600
           <idle>-0       [001] dns2.  3858.539124: my_direct_func1: my 
direct func1 ip ff60000001ba9600
        rcu_sched-14      [001] .....  3858.539208: my_direct_func1: my 
direct func1 ip 0
[...]

If I understand it right, my_direct_func1() should print the address of 
some location in the code, probably - at the beginning of the traced 
functions.

The printed values (0x0, 0x7fffffffffffffff, ...) are not valid code 
addresses.

The same issue is with ftrace-direct-multi-modify.ko.

Is anything missing here?

> 
> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> index 307a9f413edd..e944af44f681 100644
> --- a/arch/riscv/Kconfig
> +++ b/arch/riscv/Kconfig
> @@ -112,6 +112,8 @@ config RISCV
>          select HAVE_POSIX_CPU_TIMERS_TASK_WORK
>          select HAVE_REGS_AND_STACK_ACCESS_API
>          select HAVE_FUNCTION_ARG_ACCESS_API
> +       select HAVE_SAMPLE_FTRACE_DIRECT
> +       select HAVE_SAMPLE_FTRACE_DIRECT_MULTI
>          select HAVE_STACKPROTECTOR
>          select HAVE_SYSCALL_TRACEPOINTS
>          select HAVE_RSEQ
> diff --git a/samples/ftrace/ftrace-direct-modify.c b/samples/ftrace/ftrace-direct-modify.c
> index de5a0f67f320..be7bf472c3c7 100644
> --- a/samples/ftrace/ftrace-direct-modify.c
> +++ b/samples/ftrace/ftrace-direct-modify.c
> @@ -23,6 +23,39 @@ extern void my_tramp2(void *);
> 
>   static unsigned long my_ip = (unsigned long)schedule;
> 
> +#ifdef CONFIG_RISCV
> +
> +asm (" .pushsection    .text, \"ax\", @progbits\n"
> +"      .type           my_tramp1, @function\n"
> +"      .globl          my_tramp1\n"
> +"   my_tramp1:\n"
> +"      addi sp,sp,-16\n"
> +"      sd   t0,0(sp)\n"
> +"      sd   ra,8(sp)\n"
> +"      call my_direct_func1\n"
> +"      ld   t0,0(sp)\n"
> +"      ld   ra,8(sp)\n"
> +"      addi sp,sp,16\n"
> +"      jr t0\n"
> +"      .size           my_tramp1, .-my_tramp1\n"
> +
> +"      .type           my_tramp2, @function\n"
> +"      .globl          my_tramp2\n"
> +"   my_tramp2:\n"
> +"      addi sp,sp,-16\n"
> +"      sd   t0,0(sp)\n"
> +"      sd   ra,8(sp)\n"
> +"      call my_direct_func2\n"
> +"      ld   t0,0(sp)\n"
> +"      ld   ra,8(sp)\n"
> +"      addi sp,sp,16\n"
> +"      jr t0\n"
> +"      .size           my_tramp2, .-my_tramp2\n"
> +"      .popsection\n"
> +);
> +
> +#endif /* CONFIG_RISCV */
> +
>   #ifdef CONFIG_X86_64
> 
>   #include <asm/ibt.h>
> diff --git a/samples/ftrace/ftrace-direct-multi-modify.c b/samples/ftrace/ftrace-direct-multi-modify.c
> index d52370cad0b6..10884bf418f7 100644
> --- a/samples/ftrace/ftrace-direct-multi-modify.c
> +++ b/samples/ftrace/ftrace-direct-multi-modify.c
> @@ -21,6 +21,43 @@ void my_direct_func2(unsigned long ip)
>   extern void my_tramp1(void *);
>   extern void my_tramp2(void *);
> 
> +#ifdef CONFIG_RISCV
> +
> +asm (" .pushsection    .text, \"ax\", @progbits\n"
> +"      .type           my_tramp1, @function\n"
> +"      .globl          my_tramp1\n"
> +"   my_tramp1:\n"
> +"       addi sp,sp,-24\n"
> +"       sd   a0,0(sp)\n"
> +"       sd   t0,8(sp)\n"
> +"       sd   ra,16(sp)\n"
> +"       call my_direct_func1\n"
> +"       ld   a0,0(sp)\n"
> +"       ld   t0,8(sp)\n"
> +"       ld   ra,16(sp)\n"
> +"       addi sp,sp,24\n"
> +"      jr t0\n"
> +"      .size           my_tramp1, .-my_tramp1\n"
> +
> +"      .type           my_tramp2, @function\n"
> +"      .globl          my_tramp2\n"
> +"   my_tramp2:\n"
> +"       addi sp,sp,-24\n"
> +"       sd   a0,0(sp)\n"
> +"       sd   t0,8(sp)\n"
> +"       sd   ra,16(sp)\n"
> +"       call my_direct_func2\n"
> +"       ld   a0,0(sp)\n"
> +"       ld   t0,8(sp)\n"
> +"       ld   ra,16(sp)\n"
> +"       addi sp,sp,24\n"
> +"      jr t0\n"
> +"      .size           my_tramp2, .-my_tramp2\n"
> +"      .popsection\n"
> +);
> +
> +#endif /* CONFIG_RISCV */
> +
>   #ifdef CONFIG_X86_64
> 
>   #include <asm/ibt.h>
> diff --git a/samples/ftrace/ftrace-direct-multi.c b/samples/ftrace/ftrace-direct-multi.c
> index ec1088922517..a35bf43bf6d7 100644
> --- a/samples/ftrace/ftrace-direct-multi.c
> +++ b/samples/ftrace/ftrace-direct-multi.c
> @@ -16,6 +16,28 @@ void my_direct_func(unsigned long ip)
> 
>   extern void my_tramp(void *);
> 
> +#ifdef CONFIG_RISCV
> +
> +asm ("       .pushsection    .text, \"ax\", @progbits\n"
> +"       .type           my_tramp, @function\n"
> +"       .globl          my_tramp\n"
> +"   my_tramp:\n"
> +"       addi sp,sp,-24\n"
> +"       sd   a0,0(sp)\n"
> +"       sd   t0,8(sp)\n"
> +"       sd   ra,16(sp)\n"
> +"       call my_direct_func\n"
> +"       ld   a0,0(sp)\n"
> +"       ld   t0,8(sp)\n"
> +"       ld   ra,16(sp)\n"
> +"       addi sp,sp,24\n"
> +"       jr t0\n"
> +"       .size           my_tramp, .-my_tramp\n"
> +"       .popsection\n"
> +);
> +
> +#endif /* CONFIG_RISCV */
> +
>   #ifdef CONFIG_X86_64
> 
>   #include <asm/ibt.h>
> diff --git a/samples/ftrace/ftrace-direct-too.c b/samples/ftrace/ftrace-direct-too.c
> index e13fb59a2b47..3b62e33c2e6d 100644
> --- a/samples/ftrace/ftrace-direct-too.c
> +++ b/samples/ftrace/ftrace-direct-too.c
> @@ -18,6 +18,32 @@ void my_direct_func(struct vm_area_struct *vma,
> 
>   extern void my_tramp(void *);
> 
> +#ifdef CONFIG_RISCV
> +
> +asm ("       .pushsection    .text, \"ax\", @progbits\n"
> +"       .type           my_tramp, @function\n"
> +"       .globl          my_tramp\n"
> +"   my_tramp:\n"
> +"       addi sp,sp,-40\n"
> +"       sd   a0,0(sp)\n"
> +"       sd   a1,8(sp)\n"
> +"       sd   a2,16(sp)\n"
> +"       sd   t0,24(sp)\n"
> +"       sd   ra,32(sp)\n"
> +"       call my_direct_func\n"
> +"       ld   a0,0(sp)\n"
> +"       ld   a1,8(sp)\n"
> +"       ld   a2,16(sp)\n"
> +"       ld   t0,24(sp)\n"
> +"       ld   ra,32(sp)\n"
> +"       addi sp,sp,40\n"
> +"       jr t0\n"
> +"       .size           my_tramp, .-my_tramp\n"
> +"       .popsection\n"
> +);
> +
> +#endif /* CONFIG_RISCV */
> +
>   #ifdef CONFIG_X86_64
> 
>   #include <asm/ibt.h>
> diff --git a/samples/ftrace/ftrace-direct.c b/samples/ftrace/ftrace-direct.c
> index 1f769d0db20f..2cfe5a7d2d70 100644
> --- a/samples/ftrace/ftrace-direct.c
> +++ b/samples/ftrace/ftrace-direct.c
> @@ -15,6 +15,28 @@ void my_direct_func(struct task_struct *p)
> 
>   extern void my_tramp(void *);
> 
> +#ifdef CONFIG_RISCV
> +
> +asm ("       .pushsection    .text, \"ax\", @progbits\n"
> +"       .type           my_tramp, @function\n"
> +"       .globl          my_tramp\n"
> +"   my_tramp:\n"
> +"       addi sp,sp,-24\n"
> +"       sd   a0,0(sp)\n"
> +"       sd   t0,8(sp)\n"
> +"       sd   ra,16(sp)\n"
> +"       call my_direct_func\n"
> +"       ld   a0,0(sp)\n"
> +"       ld   t0,8(sp)\n"
> +"       ld   ra,16(sp)\n"
> +"       addi sp,sp,24\n"
> +"       jr t0\n"
> +"       .size           my_tramp, .-my_tramp\n"
> +"       .popsection\n"
> +);
> +
> +#endif /* CONFIG_RISCV */
> +
>   #ifdef CONFIG_X86_64
> 
>   #include <asm/ibt.h>
> --
> 2.36.1
> 
> 

Regards,
Evgenii
  

Hi, Evgenii:

Evgenii Shatokhin <e.shatokhin@yadro.com> 于2023年1月16日周一 14:30写道：

>
> Hi,
>
> On 12.01.2023 12:06, guoren@kernel.org wrote:
> > From: Song Shuai <suagrfillet@gmail.com>
> >
> > select HAVE_SAMPLE_FTRACE_DIRECT and HAVE_SAMPLE_FTRACE_DIRECT_MULTI
> > for ARCH_RV64I in arch/riscv/Kconfig. And add riscv asm code for
> > the ftrace-direct*.c files in samples/ftrace/.
> >
> > Signed-off-by: Song Shuai <suagrfillet@gmail.com>
> > Tested-by: Guo Ren <guoren@kernel.org>
> > Signed-off-by: Guo Ren <guoren@kernel.org>
> > ---
> >   arch/riscv/Kconfig                          |  2 ++
> >   samples/ftrace/ftrace-direct-modify.c       | 33 ++++++++++++++++++
> >   samples/ftrace/ftrace-direct-multi-modify.c | 37 +++++++++++++++++++++
> >   samples/ftrace/ftrace-direct-multi.c        | 22 ++++++++++++
> >   samples/ftrace/ftrace-direct-too.c          | 26 +++++++++++++++
> >   samples/ftrace/ftrace-direct.c              | 22 ++++++++++++
> >   6 files changed, 142 insertions(+)
>
> The samples were built OK now, but ftrace-direct-multi and
> ftrace-direct-multi-modify report incorrect values of ip/pc it seems.
>
> I ran 'insmod ftrace-direct-multi.ko', waited a little and then checked
> the messages in the trace:
>
> #           TASK-PID     CPU#  |||||  TIMESTAMP  FUNCTION
> #              | |         |   |||||     |         |
>       migration/1-19      [001] .....  3858.532131: my_direct_func1: my
> direct func1 ip 0
>       migration/0-15      [000] d.s2.  3858.532136: my_direct_func1: my
> direct func1 ip ff60000001ba9600
>       migration/0-15      [000] d..2.  3858.532204: my_direct_func1: my
> direct func1 ip ff60000003334d00
>       migration/0-15      [000] .....  3858.532232: my_direct_func1: my
> direct func1 ip 0
>         rcu_sched-14      [001] .....  3858.532257: my_direct_func1: my
> direct func1 ip 0
>            insmod-415     [000] .....  3858.532270: my_direct_func1: my
> direct func1 ip 7fffffffffffffff
>            <idle>-0       [001] ..s1.  3858.539051: my_direct_func1: my
> direct func1 ip ff60000001ba9600
>            <idle>-0       [001] dns2.  3858.539124: my_direct_func1: my
> direct func1 ip ff60000001ba9600
>         rcu_sched-14      [001] .....  3858.539208: my_direct_func1: my
> direct func1 ip 0
> [...]
>
> If I understand it right, my_direct_func1() should print the address of
> some location in the code, probably - at the beginning of the traced
> functions.
>
> The printed values (0x0, 0x7fffffffffffffff, ...) are not valid code
> addresses.
>
The invalid code address is only printed by accessing the schedule()
function's first argument whose address stores in a0 register.
While schedule() actually has no parameter declared, so my_direct_func
just prints the a0 in the context of the schedule()'s caller and
the address maybe varies depending on the caller.

I can't really understand why tracing the first argument of the
schedule() function, but it seems nonsense at this point.

As for this patch, it just impls a simple mcount (direct_caller) to
trace kernel functions, and basically saves the necessary ABI,
call the tracing function, and restores the ABI, just like other arches do.
so It shouldn't be blamed.

I started an independent patch to replace schedule with kick_process
to make these samples more reasonable. And It has no conflict with the
current patch, so we can go on.

Link: https://lore.kernel.org/linux-kernel/20230117091101.3669996-1-suagrfillet@gmail.com/T/#u

> The same issue is with ftrace-direct-multi-modify.ko.
>
> Is anything missing here?
>
> >
> > diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> > index 307a9f413edd..e944af44f681 100644
> > --- a/arch/riscv/Kconfig
> > +++ b/arch/riscv/Kconfig
> > @@ -112,6 +112,8 @@ config RISCV
> >          select HAVE_POSIX_CPU_TIMERS_TASK_WORK
> >          select HAVE_REGS_AND_STACK_ACCESS_API
> >          select HAVE_FUNCTION_ARG_ACCESS_API
> > +       select HAVE_SAMPLE_FTRACE_DIRECT
> > +       select HAVE_SAMPLE_FTRACE_DIRECT_MULTI
> >          select HAVE_STACKPROTECTOR
> >          select HAVE_SYSCALL_TRACEPOINTS
> >          select HAVE_RSEQ
> > diff --git a/samples/ftrace/ftrace-direct-modify.c b/samples/ftrace/ftrace-direct-modify.c
> > index de5a0f67f320..be7bf472c3c7 100644
> > --- a/samples/ftrace/ftrace-direct-modify.c
> > +++ b/samples/ftrace/ftrace-direct-modify.c
> > @@ -23,6 +23,39 @@ extern void my_tramp2(void *);
> >
> >   static unsigned long my_ip = (unsigned long)schedule;
> >
> > +#ifdef CONFIG_RISCV
> > +
> > +asm (" .pushsection    .text, \"ax\", @progbits\n"
> > +"      .type           my_tramp1, @function\n"
> > +"      .globl          my_tramp1\n"
> > +"   my_tramp1:\n"
> > +"      addi sp,sp,-16\n"
> > +"      sd   t0,0(sp)\n"
> > +"      sd   ra,8(sp)\n"
> > +"      call my_direct_func1\n"
> > +"      ld   t0,0(sp)\n"
> > +"      ld   ra,8(sp)\n"
> > +"      addi sp,sp,16\n"
> > +"      jr t0\n"
> > +"      .size           my_tramp1, .-my_tramp1\n"
> > +
> > +"      .type           my_tramp2, @function\n"
> > +"      .globl          my_tramp2\n"
> > +"   my_tramp2:\n"
> > +"      addi sp,sp,-16\n"
> > +"      sd   t0,0(sp)\n"
> > +"      sd   ra,8(sp)\n"
> > +"      call my_direct_func2\n"
> > +"      ld   t0,0(sp)\n"
> > +"      ld   ra,8(sp)\n"
> > +"      addi sp,sp,16\n"
> > +"      jr t0\n"
> > +"      .size           my_tramp2, .-my_tramp2\n"
> > +"      .popsection\n"
> > +);
> > +
> > +#endif /* CONFIG_RISCV */
> > +
> >   #ifdef CONFIG_X86_64
> >
> >   #include <asm/ibt.h>
> > diff --git a/samples/ftrace/ftrace-direct-multi-modify.c b/samples/ftrace/ftrace-direct-multi-modify.c
> > index d52370cad0b6..10884bf418f7 100644
> > --- a/samples/ftrace/ftrace-direct-multi-modify.c
> > +++ b/samples/ftrace/ftrace-direct-multi-modify.c
> > @@ -21,6 +21,43 @@ void my_direct_func2(unsigned long ip)
> >   extern void my_tramp1(void *);
> >   extern void my_tramp2(void *);
> >
> > +#ifdef CONFIG_RISCV
> > +
> > +asm (" .pushsection    .text, \"ax\", @progbits\n"
> > +"      .type           my_tramp1, @function\n"
> > +"      .globl          my_tramp1\n"
> > +"   my_tramp1:\n"
> > +"       addi sp,sp,-24\n"
> > +"       sd   a0,0(sp)\n"
> > +"       sd   t0,8(sp)\n"
> > +"       sd   ra,16(sp)\n"
> > +"       call my_direct_func1\n"
> > +"       ld   a0,0(sp)\n"
> > +"       ld   t0,8(sp)\n"
> > +"       ld   ra,16(sp)\n"
> > +"       addi sp,sp,24\n"
> > +"      jr t0\n"
> > +"      .size           my_tramp1, .-my_tramp1\n"
> > +
> > +"      .type           my_tramp2, @function\n"
> > +"      .globl          my_tramp2\n"
> > +"   my_tramp2:\n"
> > +"       addi sp,sp,-24\n"
> > +"       sd   a0,0(sp)\n"
> > +"       sd   t0,8(sp)\n"
> > +"       sd   ra,16(sp)\n"
> > +"       call my_direct_func2\n"
> > +"       ld   a0,0(sp)\n"
> > +"       ld   t0,8(sp)\n"
> > +"       ld   ra,16(sp)\n"
> > +"       addi sp,sp,24\n"
> > +"      jr t0\n"
> > +"      .size           my_tramp2, .-my_tramp2\n"
> > +"      .popsection\n"
> > +);
> > +
> > +#endif /* CONFIG_RISCV */
> > +
> >   #ifdef CONFIG_X86_64
> >
> >   #include <asm/ibt.h>
> > diff --git a/samples/ftrace/ftrace-direct-multi.c b/samples/ftrace/ftrace-direct-multi.c
> > index ec1088922517..a35bf43bf6d7 100644
> > --- a/samples/ftrace/ftrace-direct-multi.c
> > +++ b/samples/ftrace/ftrace-direct-multi.c
> > @@ -16,6 +16,28 @@ void my_direct_func(unsigned long ip)
> >
> >   extern void my_tramp(void *);
> >
> > +#ifdef CONFIG_RISCV
> > +
> > +asm ("       .pushsection    .text, \"ax\", @progbits\n"
> > +"       .type           my_tramp, @function\n"
> > +"       .globl          my_tramp\n"
> > +"   my_tramp:\n"
> > +"       addi sp,sp,-24\n"
> > +"       sd   a0,0(sp)\n"
> > +"       sd   t0,8(sp)\n"
> > +"       sd   ra,16(sp)\n"
> > +"       call my_direct_func\n"
> > +"       ld   a0,0(sp)\n"
> > +"       ld   t0,8(sp)\n"
> > +"       ld   ra,16(sp)\n"
> > +"       addi sp,sp,24\n"
> > +"       jr t0\n"
> > +"       .size           my_tramp, .-my_tramp\n"
> > +"       .popsection\n"
> > +);
> > +
> > +#endif /* CONFIG_RISCV */
> > +
> >   #ifdef CONFIG_X86_64
> >
> >   #include <asm/ibt.h>
> > diff --git a/samples/ftrace/ftrace-direct-too.c b/samples/ftrace/ftrace-direct-too.c
> > index e13fb59a2b47..3b62e33c2e6d 100644
> > --- a/samples/ftrace/ftrace-direct-too.c
> > +++ b/samples/ftrace/ftrace-direct-too.c
> > @@ -18,6 +18,32 @@ void my_direct_func(struct vm_area_struct *vma,
> >
> >   extern void my_tramp(void *);
> >
> > +#ifdef CONFIG_RISCV
> > +
> > +asm ("       .pushsection    .text, \"ax\", @progbits\n"
> > +"       .type           my_tramp, @function\n"
> > +"       .globl          my_tramp\n"
> > +"   my_tramp:\n"
> > +"       addi sp,sp,-40\n"
> > +"       sd   a0,0(sp)\n"
> > +"       sd   a1,8(sp)\n"
> > +"       sd   a2,16(sp)\n"
> > +"       sd   t0,24(sp)\n"
> > +"       sd   ra,32(sp)\n"
> > +"       call my_direct_func\n"
> > +"       ld   a0,0(sp)\n"
> > +"       ld   a1,8(sp)\n"
> > +"       ld   a2,16(sp)\n"
> > +"       ld   t0,24(sp)\n"
> > +"       ld   ra,32(sp)\n"
> > +"       addi sp,sp,40\n"
> > +"       jr t0\n"
> > +"       .size           my_tramp, .-my_tramp\n"
> > +"       .popsection\n"
> > +);
> > +
> > +#endif /* CONFIG_RISCV */
> > +
> >   #ifdef CONFIG_X86_64
> >
> >   #include <asm/ibt.h>
> > diff --git a/samples/ftrace/ftrace-direct.c b/samples/ftrace/ftrace-direct.c
> > index 1f769d0db20f..2cfe5a7d2d70 100644
> > --- a/samples/ftrace/ftrace-direct.c
> > +++ b/samples/ftrace/ftrace-direct.c
> > @@ -15,6 +15,28 @@ void my_direct_func(struct task_struct *p)
> >
> >   extern void my_tramp(void *);
> >
> > +#ifdef CONFIG_RISCV
> > +
> > +asm ("       .pushsection    .text, \"ax\", @progbits\n"
> > +"       .type           my_tramp, @function\n"
> > +"       .globl          my_tramp\n"
> > +"   my_tramp:\n"
> > +"       addi sp,sp,-24\n"
> > +"       sd   a0,0(sp)\n"
> > +"       sd   t0,8(sp)\n"
> > +"       sd   ra,16(sp)\n"
> > +"       call my_direct_func\n"
> > +"       ld   a0,0(sp)\n"
> > +"       ld   t0,8(sp)\n"
> > +"       ld   ra,16(sp)\n"
> > +"       addi sp,sp,24\n"
> > +"       jr t0\n"
> > +"       .size           my_tramp, .-my_tramp\n"
> > +"       .popsection\n"
> > +);
> > +
> > +#endif /* CONFIG_RISCV */
> > +
> >   #ifdef CONFIG_X86_64
> >
> >   #include <asm/ibt.h>
> > --
> > 2.36.1
> >
> >
>
> Regards,
> Evgenii
>
>


--
Thanks,
Song
  

Hi, Song,

On 17.01.2023 12:32, Song Shuai wrote:
> 
> Hi, Evgenii:
> 
> Evgenii Shatokhin <e.shatokhin@yadro.com> 于2023年1月16日周一 14:30写道：
> 
>>
>> Hi,
>>
>> On 12.01.2023 12:06, guoren@kernel.org wrote:
>>> From: Song Shuai <suagrfillet@gmail.com>
>>>
>>> select HAVE_SAMPLE_FTRACE_DIRECT and HAVE_SAMPLE_FTRACE_DIRECT_MULTI
>>> for ARCH_RV64I in arch/riscv/Kconfig. And add riscv asm code for
>>> the ftrace-direct*.c files in samples/ftrace/.
>>>
>>> Signed-off-by: Song Shuai <suagrfillet@gmail.com>
>>> Tested-by: Guo Ren <guoren@kernel.org>
>>> Signed-off-by: Guo Ren <guoren@kernel.org>
>>> ---
>>>    arch/riscv/Kconfig                          |  2 ++
>>>    samples/ftrace/ftrace-direct-modify.c       | 33 ++++++++++++++++++
>>>    samples/ftrace/ftrace-direct-multi-modify.c | 37 +++++++++++++++++++++
>>>    samples/ftrace/ftrace-direct-multi.c        | 22 ++++++++++++
>>>    samples/ftrace/ftrace-direct-too.c          | 26 +++++++++++++++
>>>    samples/ftrace/ftrace-direct.c              | 22 ++++++++++++
>>>    6 files changed, 142 insertions(+)
>>
>> The samples were built OK now, but ftrace-direct-multi and
>> ftrace-direct-multi-modify report incorrect values of ip/pc it seems.
>>
>> I ran 'insmod ftrace-direct-multi.ko', waited a little and then checked
>> the messages in the trace:
>>
>> #           TASK-PID     CPU#  |||||  TIMESTAMP  FUNCTION
>> #              | |         |   |||||     |         |
>>        migration/1-19      [001] .....  3858.532131: my_direct_func1: my
>> direct func1 ip 0
>>        migration/0-15      [000] d.s2.  3858.532136: my_direct_func1: my
>> direct func1 ip ff60000001ba9600
>>        migration/0-15      [000] d..2.  3858.532204: my_direct_func1: my
>> direct func1 ip ff60000003334d00
>>        migration/0-15      [000] .....  3858.532232: my_direct_func1: my
>> direct func1 ip 0
>>          rcu_sched-14      [001] .....  3858.532257: my_direct_func1: my
>> direct func1 ip 0
>>             insmod-415     [000] .....  3858.532270: my_direct_func1: my
>> direct func1 ip 7fffffffffffffff
>>             <idle>-0       [001] ..s1.  3858.539051: my_direct_func1: my
>> direct func1 ip ff60000001ba9600
>>             <idle>-0       [001] dns2.  3858.539124: my_direct_func1: my
>> direct func1 ip ff60000001ba9600
>>          rcu_sched-14      [001] .....  3858.539208: my_direct_func1: my
>> direct func1 ip 0
>> [...]
>>
>> If I understand it right, my_direct_func1() should print the address of
>> some location in the code, probably - at the beginning of the traced
>> functions.
>>
>> The printed values (0x0, 0x7fffffffffffffff, ...) are not valid code
>> addresses.
>>
> The invalid code address is only printed by accessing the schedule()
> function's first argument whose address stores in a0 register.
> While schedule() actually has no parameter declared, so my_direct_func
> just prints the a0 in the context of the schedule()'s caller and
> the address maybe varies depending on the caller.
> 
> I can't really understand why tracing the first argument of the
> schedule() function, but it seems nonsense at this point.

The question is, what should be passed as the argument(s) of 
my_direct_func() in this particular sample module. The kernel docs and 
commit logs seem to contain no info on that.

With direct functions, I suppose, the trampoline can pass anything it 
wants to my_direct_func(), not just the arguments of the traced function.

I'd check what these sample modules do on x86 and would try to match 
that behaviour on RISC-V.

> 
> As for this patch, it just impls a simple mcount (direct_caller) to
> trace kernel functions, and basically saves the necessary ABI,
> call the tracing function, and restores the ABI, just like other arches do.
> so It shouldn't be blamed.
> 
> I started an independent patch to replace schedule with kick_process
> to make these samples more reasonable. And It has no conflict with the
> current patch, so we can go on.
> 
> Link: https://lore.kernel.org/linux-kernel/20230117091101.3669996-1-suagrfillet@gmail.com/T/#u
> 
>> The same issue is with ftrace-direct-multi-modify.ko.
>>
>> Is anything missing here?
>>
>>>
>>> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
>>> index 307a9f413edd..e944af44f681 100644
>>> --- a/arch/riscv/Kconfig
>>> +++ b/arch/riscv/Kconfig
>>> @@ -112,6 +112,8 @@ config RISCV
>>>           select HAVE_POSIX_CPU_TIMERS_TASK_WORK
>>>           select HAVE_REGS_AND_STACK_ACCESS_API
>>>           select HAVE_FUNCTION_ARG_ACCESS_API
>>> +       select HAVE_SAMPLE_FTRACE_DIRECT
>>> +       select HAVE_SAMPLE_FTRACE_DIRECT_MULTI
>>>           select HAVE_STACKPROTECTOR
>>>           select HAVE_SYSCALL_TRACEPOINTS
>>>           select HAVE_RSEQ
>>> diff --git a/samples/ftrace/ftrace-direct-modify.c b/samples/ftrace/ftrace-direct-modify.c
>>> index de5a0f67f320..be7bf472c3c7 100644
>>> --- a/samples/ftrace/ftrace-direct-modify.c
>>> +++ b/samples/ftrace/ftrace-direct-modify.c
>>> @@ -23,6 +23,39 @@ extern void my_tramp2(void *);
>>>
>>>    static unsigned long my_ip = (unsigned long)schedule;
>>>
>>> +#ifdef CONFIG_RISCV
>>> +
>>> +asm (" .pushsection    .text, \"ax\", @progbits\n"
>>> +"      .type           my_tramp1, @function\n"
>>> +"      .globl          my_tramp1\n"
>>> +"   my_tramp1:\n"
>>> +"      addi sp,sp,-16\n"
>>> +"      sd   t0,0(sp)\n"
>>> +"      sd   ra,8(sp)\n"
>>> +"      call my_direct_func1\n"
>>> +"      ld   t0,0(sp)\n"
>>> +"      ld   ra,8(sp)\n"
>>> +"      addi sp,sp,16\n"
>>> +"      jr t0\n"
>>> +"      .size           my_tramp1, .-my_tramp1\n"
>>> +
>>> +"      .type           my_tramp2, @function\n"
>>> +"      .globl          my_tramp2\n"
>>> +"   my_tramp2:\n"
>>> +"      addi sp,sp,-16\n"
>>> +"      sd   t0,0(sp)\n"
>>> +"      sd   ra,8(sp)\n"
>>> +"      call my_direct_func2\n"
>>> +"      ld   t0,0(sp)\n"
>>> +"      ld   ra,8(sp)\n"
>>> +"      addi sp,sp,16\n"
>>> +"      jr t0\n"
>>> +"      .size           my_tramp2, .-my_tramp2\n"
>>> +"      .popsection\n"
>>> +);
>>> +
>>> +#endif /* CONFIG_RISCV */
>>> +
>>>    #ifdef CONFIG_X86_64
>>>
>>>    #include <asm/ibt.h>
>>> diff --git a/samples/ftrace/ftrace-direct-multi-modify.c b/samples/ftrace/ftrace-direct-multi-modify.c
>>> index d52370cad0b6..10884bf418f7 100644
>>> --- a/samples/ftrace/ftrace-direct-multi-modify.c
>>> +++ b/samples/ftrace/ftrace-direct-multi-modify.c
>>> @@ -21,6 +21,43 @@ void my_direct_func2(unsigned long ip)
>>>    extern void my_tramp1(void *);
>>>    extern void my_tramp2(void *);
>>>
>>> +#ifdef CONFIG_RISCV
>>> +
>>> +asm (" .pushsection    .text, \"ax\", @progbits\n"
>>> +"      .type           my_tramp1, @function\n"
>>> +"      .globl          my_tramp1\n"
>>> +"   my_tramp1:\n"
>>> +"       addi sp,sp,-24\n"
>>> +"       sd   a0,0(sp)\n"
>>> +"       sd   t0,8(sp)\n"
>>> +"       sd   ra,16(sp)\n"
>>> +"       call my_direct_func1\n"
>>> +"       ld   a0,0(sp)\n"
>>> +"       ld   t0,8(sp)\n"
>>> +"       ld   ra,16(sp)\n"
>>> +"       addi sp,sp,24\n"
>>> +"      jr t0\n"
>>> +"      .size           my_tramp1, .-my_tramp1\n"
>>> +
>>> +"      .type           my_tramp2, @function\n"
>>> +"      .globl          my_tramp2\n"
>>> +"   my_tramp2:\n"
>>> +"       addi sp,sp,-24\n"
>>> +"       sd   a0,0(sp)\n"
>>> +"       sd   t0,8(sp)\n"
>>> +"       sd   ra,16(sp)\n"
>>> +"       call my_direct_func2\n"
>>> +"       ld   a0,0(sp)\n"
>>> +"       ld   t0,8(sp)\n"
>>> +"       ld   ra,16(sp)\n"
>>> +"       addi sp,sp,24\n"
>>> +"      jr t0\n"
>>> +"      .size           my_tramp2, .-my_tramp2\n"
>>> +"      .popsection\n"
>>> +);
>>> +
>>> +#endif /* CONFIG_RISCV */
>>> +
>>>    #ifdef CONFIG_X86_64
>>>
>>>    #include <asm/ibt.h>
>>> diff --git a/samples/ftrace/ftrace-direct-multi.c b/samples/ftrace/ftrace-direct-multi.c
>>> index ec1088922517..a35bf43bf6d7 100644
>>> --- a/samples/ftrace/ftrace-direct-multi.c
>>> +++ b/samples/ftrace/ftrace-direct-multi.c
>>> @@ -16,6 +16,28 @@ void my_direct_func(unsigned long ip)
>>>
>>>    extern void my_tramp(void *);
>>>
>>> +#ifdef CONFIG_RISCV
>>> +
>>> +asm ("       .pushsection    .text, \"ax\", @progbits\n"
>>> +"       .type           my_tramp, @function\n"
>>> +"       .globl          my_tramp\n"
>>> +"   my_tramp:\n"
>>> +"       addi sp,sp,-24\n"
>>> +"       sd   a0,0(sp)\n"
>>> +"       sd   t0,8(sp)\n"
>>> +"       sd   ra,16(sp)\n"
>>> +"       call my_direct_func\n"
>>> +"       ld   a0,0(sp)\n"
>>> +"       ld   t0,8(sp)\n"
>>> +"       ld   ra,16(sp)\n"
>>> +"       addi sp,sp,24\n"
>>> +"       jr t0\n"
>>> +"       .size           my_tramp, .-my_tramp\n"
>>> +"       .popsection\n"
>>> +);
>>> +
>>> +#endif /* CONFIG_RISCV */
>>> +
>>>    #ifdef CONFIG_X86_64
>>>
>>>    #include <asm/ibt.h>
>>> diff --git a/samples/ftrace/ftrace-direct-too.c b/samples/ftrace/ftrace-direct-too.c
>>> index e13fb59a2b47..3b62e33c2e6d 100644
>>> --- a/samples/ftrace/ftrace-direct-too.c
>>> +++ b/samples/ftrace/ftrace-direct-too.c
>>> @@ -18,6 +18,32 @@ void my_direct_func(struct vm_area_struct *vma,
>>>
>>>    extern void my_tramp(void *);
>>>
>>> +#ifdef CONFIG_RISCV
>>> +
>>> +asm ("       .pushsection    .text, \"ax\", @progbits\n"
>>> +"       .type           my_tramp, @function\n"
>>> +"       .globl          my_tramp\n"
>>> +"   my_tramp:\n"
>>> +"       addi sp,sp,-40\n"
>>> +"       sd   a0,0(sp)\n"
>>> +"       sd   a1,8(sp)\n"
>>> +"       sd   a2,16(sp)\n"
>>> +"       sd   t0,24(sp)\n"
>>> +"       sd   ra,32(sp)\n"
>>> +"       call my_direct_func\n"
>>> +"       ld   a0,0(sp)\n"
>>> +"       ld   a1,8(sp)\n"
>>> +"       ld   a2,16(sp)\n"
>>> +"       ld   t0,24(sp)\n"
>>> +"       ld   ra,32(sp)\n"
>>> +"       addi sp,sp,40\n"
>>> +"       jr t0\n"
>>> +"       .size           my_tramp, .-my_tramp\n"
>>> +"       .popsection\n"
>>> +);
>>> +
>>> +#endif /* CONFIG_RISCV */
>>> +
>>>    #ifdef CONFIG_X86_64
>>>
>>>    #include <asm/ibt.h>
>>> diff --git a/samples/ftrace/ftrace-direct.c b/samples/ftrace/ftrace-direct.c
>>> index 1f769d0db20f..2cfe5a7d2d70 100644
>>> --- a/samples/ftrace/ftrace-direct.c
>>> +++ b/samples/ftrace/ftrace-direct.c
>>> @@ -15,6 +15,28 @@ void my_direct_func(struct task_struct *p)
>>>
>>>    extern void my_tramp(void *);
>>>
>>> +#ifdef CONFIG_RISCV
>>> +
>>> +asm ("       .pushsection    .text, \"ax\", @progbits\n"
>>> +"       .type           my_tramp, @function\n"
>>> +"       .globl          my_tramp\n"
>>> +"   my_tramp:\n"
>>> +"       addi sp,sp,-24\n"
>>> +"       sd   a0,0(sp)\n"
>>> +"       sd   t0,8(sp)\n"
>>> +"       sd   ra,16(sp)\n"
>>> +"       call my_direct_func\n"
>>> +"       ld   a0,0(sp)\n"
>>> +"       ld   t0,8(sp)\n"
>>> +"       ld   ra,16(sp)\n"
>>> +"       addi sp,sp,24\n"
>>> +"       jr t0\n"
>>> +"       .size           my_tramp, .-my_tramp\n"
>>> +"       .popsection\n"
>>> +);
>>> +
>>> +#endif /* CONFIG_RISCV */
>>> +
>>>    #ifdef CONFIG_X86_64
>>>
>>>    #include <asm/ibt.h>
>>> --
>>> 2.36.1
> 
> --
> Thanks,
> Song
> 

Regards,
Evgenii
  

On 17.01.2023 16:16, Evgenii Shatokhin wrote:
> Hi, Song,
> 
> On 17.01.2023 12:32, Song Shuai wrote:
>>
>> Hi, Evgenii:
>>
>> Evgenii Shatokhin <e.shatokhin@yadro.com> 于2023年1月16日周一 14:30写道：
>>
>>>
>>> Hi,
>>>
>>> On 12.01.2023 12:06, guoren@kernel.org wrote:
>>>> From: Song Shuai <suagrfillet@gmail.com>
>>>>
>>>> select HAVE_SAMPLE_FTRACE_DIRECT and HAVE_SAMPLE_FTRACE_DIRECT_MULTI
>>>> for ARCH_RV64I in arch/riscv/Kconfig. And add riscv asm code for
>>>> the ftrace-direct*.c files in samples/ftrace/.
>>>>
>>>> Signed-off-by: Song Shuai <suagrfillet@gmail.com>
>>>> Tested-by: Guo Ren <guoren@kernel.org>
>>>> Signed-off-by: Guo Ren <guoren@kernel.org>
>>>> ---
>>>>    arch/riscv/Kconfig                          |  2 ++
>>>>    samples/ftrace/ftrace-direct-modify.c       | 33 ++++++++++++++++++
>>>>    samples/ftrace/ftrace-direct-multi-modify.c | 37 
>>>> +++++++++++++++++++++
>>>>    samples/ftrace/ftrace-direct-multi.c        | 22 ++++++++++++
>>>>    samples/ftrace/ftrace-direct-too.c          | 26 +++++++++++++++
>>>>    samples/ftrace/ftrace-direct.c              | 22 ++++++++++++
>>>>    6 files changed, 142 insertions(+)
>>>
>>> The samples were built OK now, but ftrace-direct-multi and
>>> ftrace-direct-multi-modify report incorrect values of ip/pc it seems.
>>>
>>> I ran 'insmod ftrace-direct-multi.ko', waited a little and then checked
>>> the messages in the trace:
>>>
>>> #           TASK-PID     CPU#  |||||  TIMESTAMP  FUNCTION
>>> #              | |         |   |||||     |         |
>>>        migration/1-19      [001] .....  3858.532131: my_direct_func1: my
>>> direct func1 ip 0
>>>        migration/0-15      [000] d.s2.  3858.532136: my_direct_func1: my
>>> direct func1 ip ff60000001ba9600
>>>        migration/0-15      [000] d..2.  3858.532204: my_direct_func1: my
>>> direct func1 ip ff60000003334d00
>>>        migration/0-15      [000] .....  3858.532232: my_direct_func1: my
>>> direct func1 ip 0
>>>          rcu_sched-14      [001] .....  3858.532257: my_direct_func1: my
>>> direct func1 ip 0
>>>             insmod-415     [000] .....  3858.532270: my_direct_func1: my
>>> direct func1 ip 7fffffffffffffff
>>>             <idle>-0       [001] ..s1.  3858.539051: my_direct_func1: my
>>> direct func1 ip ff60000001ba9600
>>>             <idle>-0       [001] dns2.  3858.539124: my_direct_func1: my
>>> direct func1 ip ff60000001ba9600
>>>          rcu_sched-14      [001] .....  3858.539208: my_direct_func1: my
>>> direct func1 ip 0
>>> [...]
>>>
>>> If I understand it right, my_direct_func1() should print the address of
>>> some location in the code, probably - at the beginning of the traced
>>> functions.
>>>
>>> The printed values (0x0, 0x7fffffffffffffff, ...) are not valid code
>>> addresses.
>>>
>> The invalid code address is only printed by accessing the schedule()
>> function's first argument whose address stores in a0 register.
>> While schedule() actually has no parameter declared, so my_direct_func
>> just prints the a0 in the context of the schedule()'s caller and
>> the address maybe varies depending on the caller.
>>
>> I can't really understand why tracing the first argument of the
>> schedule() function, but it seems nonsense at this point.
> 
> The question is, what should be passed as the argument(s) of 
> my_direct_func() in this particular sample module. The kernel docs and 
> commit logs seem to contain no info on that.
> 
> With direct functions, I suppose, the trampoline can pass anything it 
> wants to my_direct_func(), not just the arguments of the traced function.
> 
> I'd check what these sample modules do on x86 and would try to match 
> that behaviour on RISC-V.

I have checked ftrace-direct-multi.ko and ftrace-direct-multi-modify.ko 
on 6.2-rc4 built for x86-64 - yes, ip/pc in the traced function should 
be passed to my_direct_func().

ftrace-direct-multi.ko:
#           TASK-PID     CPU#  |||||  TIMESTAMP  FUNCTION
#              | |         |   |||||     |         |
           insmod-10829   [000] d.h1.  1719.518535: my_direct_func: ip 
ffffffff87332f45 // wake_up_process+0x5
  rcu_tasks_kthre-11      [000] .....  1719.518696: my_direct_func: ip 
ffffffff8828d935 // schedule+0x5
           insmod-10829   [000] .....  1719.518708: my_direct_func: ip 
ffffffff8828d935
  systemd-journal-293     [001] .....  1719.518823: my_direct_func: ip 
ffffffff8828d935
          systemd-1       [000] .....  1719.519141: my_direct_func: ip 
ffffffff8828d935
           <idle>-0       [001] ..s1.  1719.521889: my_direct_func: ip 
ffffffff87332f45
           <idle>-0       [000] d.s2.  1719.521901: my_direct_func: ip 
ffffffff87332f45
      rcu_preempt-15      [001] .....  1719.521917: my_direct_func: ip 
ffffffff8828d935
[...]

The ip values are wake_up_process+0x5 and schedule+0x5, the locations 
where the execution of the traced functions resumes after the Ftrace 
trampoline has finished.

The results with ftrace-direct-multi-modify.ko are similar to that.

The samples look like a demonstration, that one can pass anything 
necessary to the handler in case of "direct" functions.

I suppose, the RISC-V-specific asm code in these two sample modules 
could be updated to pass the saved pc value to my_direct_func() in a0.

> 
>>
>> As for this patch, it just impls a simple mcount (direct_caller) to
>> trace kernel functions, and basically saves the necessary ABI,
>> call the tracing function, and restores the ABI, just like other 
>> arches do.
>> so It shouldn't be blamed.
>>
>> I started an independent patch to replace schedule with kick_process
>> to make these samples more reasonable. And It has no conflict with the
>> current patch, so we can go on.
>>
>> Link: 
>> https://lore.kernel.org/linux-kernel/20230117091101.3669996-1-suagrfillet@gmail.com/T/#u
>>
>>> The same issue is with ftrace-direct-multi-modify.ko.
>>>
>>> Is anything missing here?
>>>
>>>>
>>>> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
>>>> index 307a9f413edd..e944af44f681 100644
>>>> --- a/arch/riscv/Kconfig
>>>> +++ b/arch/riscv/Kconfig
>>>> @@ -112,6 +112,8 @@ config RISCV
>>>>           select HAVE_POSIX_CPU_TIMERS_TASK_WORK
>>>>           select HAVE_REGS_AND_STACK_ACCESS_API
>>>>           select HAVE_FUNCTION_ARG_ACCESS_API
>>>> +       select HAVE_SAMPLE_FTRACE_DIRECT
>>>> +       select HAVE_SAMPLE_FTRACE_DIRECT_MULTI
>>>>           select HAVE_STACKPROTECTOR
>>>>           select HAVE_SYSCALL_TRACEPOINTS
>>>>           select HAVE_RSEQ
>>>> diff --git a/samples/ftrace/ftrace-direct-modify.c 
>>>> b/samples/ftrace/ftrace-direct-modify.c
>>>> index de5a0f67f320..be7bf472c3c7 100644
>>>> --- a/samples/ftrace/ftrace-direct-modify.c
>>>> +++ b/samples/ftrace/ftrace-direct-modify.c
>>>> @@ -23,6 +23,39 @@ extern void my_tramp2(void *);
>>>>
>>>>    static unsigned long my_ip = (unsigned long)schedule;
>>>>
>>>> +#ifdef CONFIG_RISCV
>>>> +
>>>> +asm (" .pushsection    .text, \"ax\", @progbits\n"
>>>> +"      .type           my_tramp1, @function\n"
>>>> +"      .globl          my_tramp1\n"
>>>> +"   my_tramp1:\n"
>>>> +"      addi sp,sp,-16\n"
>>>> +"      sd   t0,0(sp)\n"
>>>> +"      sd   ra,8(sp)\n"
>>>> +"      call my_direct_func1\n"
>>>> +"      ld   t0,0(sp)\n"
>>>> +"      ld   ra,8(sp)\n"
>>>> +"      addi sp,sp,16\n"
>>>> +"      jr t0\n"
>>>> +"      .size           my_tramp1, .-my_tramp1\n"
>>>> +
>>>> +"      .type           my_tramp2, @function\n"
>>>> +"      .globl          my_tramp2\n"
>>>> +"   my_tramp2:\n"
>>>> +"      addi sp,sp,-16\n"
>>>> +"      sd   t0,0(sp)\n"
>>>> +"      sd   ra,8(sp)\n"
>>>> +"      call my_direct_func2\n"
>>>> +"      ld   t0,0(sp)\n"
>>>> +"      ld   ra,8(sp)\n"
>>>> +"      addi sp,sp,16\n"
>>>> +"      jr t0\n"
>>>> +"      .size           my_tramp2, .-my_tramp2\n"
>>>> +"      .popsection\n"
>>>> +);
>>>> +
>>>> +#endif /* CONFIG_RISCV */
>>>> +
>>>>    #ifdef CONFIG_X86_64
>>>>
>>>>    #include <asm/ibt.h>
>>>> diff --git a/samples/ftrace/ftrace-direct-multi-modify.c 
>>>> b/samples/ftrace/ftrace-direct-multi-modify.c
>>>> index d52370cad0b6..10884bf418f7 100644
>>>> --- a/samples/ftrace/ftrace-direct-multi-modify.c
>>>> +++ b/samples/ftrace/ftrace-direct-multi-modify.c
>>>> @@ -21,6 +21,43 @@ void my_direct_func2(unsigned long ip)
>>>>    extern void my_tramp1(void *);
>>>>    extern void my_tramp2(void *);
>>>>
>>>> +#ifdef CONFIG_RISCV
>>>> +
>>>> +asm (" .pushsection    .text, \"ax\", @progbits\n"
>>>> +"      .type           my_tramp1, @function\n"
>>>> +"      .globl          my_tramp1\n"
>>>> +"   my_tramp1:\n"
>>>> +"       addi sp,sp,-24\n"
>>>> +"       sd   a0,0(sp)\n"
>>>> +"       sd   t0,8(sp)\n"
>>>> +"       sd   ra,16(sp)\n"
>>>> +"       call my_direct_func1\n"
>>>> +"       ld   a0,0(sp)\n"
>>>> +"       ld   t0,8(sp)\n"
>>>> +"       ld   ra,16(sp)\n"
>>>> +"       addi sp,sp,24\n"
>>>> +"      jr t0\n"
>>>> +"      .size           my_tramp1, .-my_tramp1\n"
>>>> +
>>>> +"      .type           my_tramp2, @function\n"
>>>> +"      .globl          my_tramp2\n"
>>>> +"   my_tramp2:\n"
>>>> +"       addi sp,sp,-24\n"
>>>> +"       sd   a0,0(sp)\n"
>>>> +"       sd   t0,8(sp)\n"
>>>> +"       sd   ra,16(sp)\n"
>>>> +"       call my_direct_func2\n"
>>>> +"       ld   a0,0(sp)\n"
>>>> +"       ld   t0,8(sp)\n"
>>>> +"       ld   ra,16(sp)\n"
>>>> +"       addi sp,sp,24\n"
>>>> +"      jr t0\n"
>>>> +"      .size           my_tramp2, .-my_tramp2\n"
>>>> +"      .popsection\n"
>>>> +);
>>>> +
>>>> +#endif /* CONFIG_RISCV */
>>>> +
>>>>    #ifdef CONFIG_X86_64
>>>>
>>>>    #include <asm/ibt.h>
>>>> diff --git a/samples/ftrace/ftrace-direct-multi.c 
>>>> b/samples/ftrace/ftrace-direct-multi.c
>>>> index ec1088922517..a35bf43bf6d7 100644
>>>> --- a/samples/ftrace/ftrace-direct-multi.c
>>>> +++ b/samples/ftrace/ftrace-direct-multi.c
>>>> @@ -16,6 +16,28 @@ void my_direct_func(unsigned long ip)
>>>>
>>>>    extern void my_tramp(void *);
>>>>
>>>> +#ifdef CONFIG_RISCV
>>>> +
>>>> +asm ("       .pushsection    .text, \"ax\", @progbits\n"
>>>> +"       .type           my_tramp, @function\n"
>>>> +"       .globl          my_tramp\n"
>>>> +"   my_tramp:\n"
>>>> +"       addi sp,sp,-24\n"
>>>> +"       sd   a0,0(sp)\n"
>>>> +"       sd   t0,8(sp)\n"
>>>> +"       sd   ra,16(sp)\n"
>>>> +"       call my_direct_func\n"
>>>> +"       ld   a0,0(sp)\n"
>>>> +"       ld   t0,8(sp)\n"
>>>> +"       ld   ra,16(sp)\n"
>>>> +"       addi sp,sp,24\n"
>>>> +"       jr t0\n"
>>>> +"       .size           my_tramp, .-my_tramp\n"
>>>> +"       .popsection\n"
>>>> +);
>>>> +
>>>> +#endif /* CONFIG_RISCV */
>>>> +
>>>>    #ifdef CONFIG_X86_64
>>>>
>>>>    #include <asm/ibt.h>
>>>> diff --git a/samples/ftrace/ftrace-direct-too.c 
>>>> b/samples/ftrace/ftrace-direct-too.c
>>>> index e13fb59a2b47..3b62e33c2e6d 100644
>>>> --- a/samples/ftrace/ftrace-direct-too.c
>>>> +++ b/samples/ftrace/ftrace-direct-too.c
>>>> @@ -18,6 +18,32 @@ void my_direct_func(struct vm_area_struct *vma,
>>>>
>>>>    extern void my_tramp(void *);
>>>>
>>>> +#ifdef CONFIG_RISCV
>>>> +
>>>> +asm ("       .pushsection    .text, \"ax\", @progbits\n"
>>>> +"       .type           my_tramp, @function\n"
>>>> +"       .globl          my_tramp\n"
>>>> +"   my_tramp:\n"
>>>> +"       addi sp,sp,-40\n"
>>>> +"       sd   a0,0(sp)\n"
>>>> +"       sd   a1,8(sp)\n"
>>>> +"       sd   a2,16(sp)\n"
>>>> +"       sd   t0,24(sp)\n"
>>>> +"       sd   ra,32(sp)\n"
>>>> +"       call my_direct_func\n"
>>>> +"       ld   a0,0(sp)\n"
>>>> +"       ld   a1,8(sp)\n"
>>>> +"       ld   a2,16(sp)\n"
>>>> +"       ld   t0,24(sp)\n"
>>>> +"       ld   ra,32(sp)\n"
>>>> +"       addi sp,sp,40\n"
>>>> +"       jr t0\n"
>>>> +"       .size           my_tramp, .-my_tramp\n"
>>>> +"       .popsection\n"
>>>> +);
>>>> +
>>>> +#endif /* CONFIG_RISCV */
>>>> +
>>>>    #ifdef CONFIG_X86_64
>>>>
>>>>    #include <asm/ibt.h>
>>>> diff --git a/samples/ftrace/ftrace-direct.c 
>>>> b/samples/ftrace/ftrace-direct.c
>>>> index 1f769d0db20f..2cfe5a7d2d70 100644
>>>> --- a/samples/ftrace/ftrace-direct.c
>>>> +++ b/samples/ftrace/ftrace-direct.c
>>>> @@ -15,6 +15,28 @@ void my_direct_func(struct task_struct *p)
>>>>
>>>>    extern void my_tramp(void *);
>>>>
>>>> +#ifdef CONFIG_RISCV
>>>> +
>>>> +asm ("       .pushsection    .text, \"ax\", @progbits\n"
>>>> +"       .type           my_tramp, @function\n"
>>>> +"       .globl          my_tramp\n"
>>>> +"   my_tramp:\n"
>>>> +"       addi sp,sp,-24\n"
>>>> +"       sd   a0,0(sp)\n"
>>>> +"       sd   t0,8(sp)\n"
>>>> +"       sd   ra,16(sp)\n"
>>>> +"       call my_direct_func\n"
>>>> +"       ld   a0,0(sp)\n"
>>>> +"       ld   t0,8(sp)\n"
>>>> +"       ld   ra,16(sp)\n"
>>>> +"       addi sp,sp,24\n"
>>>> +"       jr t0\n"
>>>> +"       .size           my_tramp, .-my_tramp\n"
>>>> +"       .popsection\n"
>>>> +);
>>>> +
>>>> +#endif /* CONFIG_RISCV */
>>>> +
>>>>    #ifdef CONFIG_X86_64
>>>>
>>>>    #include <asm/ibt.h>
>>>> -- 
>>>> 2.36.1
>>
>> -- 
>> Thanks,
>> Song
>>
> 
> Regards,
> Evgenii
  

Evgenii Shatokhin <e.shatokhin@yadro.com> 于2023年1月17日周二 16:22写道：
>
> On 17.01.2023 16:16, Evgenii Shatokhin wrote:
> > Hi, Song,
> >
> > On 17.01.2023 12:32, Song Shuai wrote:
> >>
> >> Hi, Evgenii:
> >>
> >> Evgenii Shatokhin <e.shatokhin@yadro.com> 于2023年1月16日周一 14:30写道：
> >>
> >>>
> >>> Hi,
> >>>
> >>> On 12.01.2023 12:06, guoren@kernel.org wrote:
> >>>> From: Song Shuai <suagrfillet@gmail.com>
> >>>>
> >>>> select HAVE_SAMPLE_FTRACE_DIRECT and HAVE_SAMPLE_FTRACE_DIRECT_MULTI
> >>>> for ARCH_RV64I in arch/riscv/Kconfig. And add riscv asm code for
> >>>> the ftrace-direct*.c files in samples/ftrace/.
> >>>>
> >>>> Signed-off-by: Song Shuai <suagrfillet@gmail.com>
> >>>> Tested-by: Guo Ren <guoren@kernel.org>
> >>>> Signed-off-by: Guo Ren <guoren@kernel.org>
> >>>> ---
> >>>>    arch/riscv/Kconfig                          |  2 ++
> >>>>    samples/ftrace/ftrace-direct-modify.c       | 33 ++++++++++++++++++
> >>>>    samples/ftrace/ftrace-direct-multi-modify.c | 37
> >>>> +++++++++++++++++++++
> >>>>    samples/ftrace/ftrace-direct-multi.c        | 22 ++++++++++++
> >>>>    samples/ftrace/ftrace-direct-too.c          | 26 +++++++++++++++
> >>>>    samples/ftrace/ftrace-direct.c              | 22 ++++++++++++
> >>>>    6 files changed, 142 insertions(+)
> >>>
> >>> The samples were built OK now, but ftrace-direct-multi and
> >>> ftrace-direct-multi-modify report incorrect values of ip/pc it seems.
> >>>
> >>> I ran 'insmod ftrace-direct-multi.ko', waited a little and then checked
> >>> the messages in the trace:
> >>>
> >>> #           TASK-PID     CPU#  |||||  TIMESTAMP  FUNCTION
> >>> #              | |         |   |||||     |         |
> >>>        migration/1-19      [001] .....  3858.532131: my_direct_func1: my
> >>> direct func1 ip 0
> >>>        migration/0-15      [000] d.s2.  3858.532136: my_direct_func1: my
> >>> direct func1 ip ff60000001ba9600
> >>>        migration/0-15      [000] d..2.  3858.532204: my_direct_func1: my
> >>> direct func1 ip ff60000003334d00
> >>>        migration/0-15      [000] .....  3858.532232: my_direct_func1: my
> >>> direct func1 ip 0
> >>>          rcu_sched-14      [001] .....  3858.532257: my_direct_func1: my
> >>> direct func1 ip 0
> >>>             insmod-415     [000] .....  3858.532270: my_direct_func1: my
> >>> direct func1 ip 7fffffffffffffff
> >>>             <idle>-0       [001] ..s1.  3858.539051: my_direct_func1: my
> >>> direct func1 ip ff60000001ba9600
> >>>             <idle>-0       [001] dns2.  3858.539124: my_direct_func1: my
> >>> direct func1 ip ff60000001ba9600
> >>>          rcu_sched-14      [001] .....  3858.539208: my_direct_func1: my
> >>> direct func1 ip 0
> >>> [...]
> >>>
> >>> If I understand it right, my_direct_func1() should print the address of
> >>> some location in the code, probably - at the beginning of the traced
> >>> functions.
> >>>
> >>> The printed values (0x0, 0x7fffffffffffffff, ...) are not valid code
> >>> addresses.
> >>>
> >> The invalid code address is only printed by accessing the schedule()
> >> function's first argument whose address stores in a0 register.
> >> While schedule() actually has no parameter declared, so my_direct_func
> >> just prints the a0 in the context of the schedule()'s caller and
> >> the address maybe varies depending on the caller.
> >>
> >> I can't really understand why tracing the first argument of the
> >> schedule() function, but it seems nonsense at this point.
> >
> > The question is, what should be passed as the argument(s) of
> > my_direct_func() in this particular sample module. The kernel docs and
> > commit logs seem to contain no info on that.
> >
> > With direct functions, I suppose, the trampoline can pass anything it
> > wants to my_direct_func(), not just the arguments of the traced function.
> >
> > I'd check what these sample modules do on x86 and would try to match
> > that behaviour on RISC-V.
>
> I have checked ftrace-direct-multi.ko and ftrace-direct-multi-modify.ko
> on 6.2-rc4 built for x86-64 - yes, ip/pc in the traced function should
> be passed to my_direct_func().
>
> ftrace-direct-multi.ko:
> #           TASK-PID     CPU#  |||||  TIMESTAMP  FUNCTION
> #              | |         |   |||||     |         |
>            insmod-10829   [000] d.h1.  1719.518535: my_direct_func: ip
> ffffffff87332f45 // wake_up_process+0x5
>   rcu_tasks_kthre-11      [000] .....  1719.518696: my_direct_func: ip
> ffffffff8828d935 // schedule+0x5
>            insmod-10829   [000] .....  1719.518708: my_direct_func: ip
> ffffffff8828d935
>   systemd-journal-293     [001] .....  1719.518823: my_direct_func: ip
> ffffffff8828d935
>           systemd-1       [000] .....  1719.519141: my_direct_func: ip
> ffffffff8828d935
>            <idle>-0       [001] ..s1.  1719.521889: my_direct_func: ip
> ffffffff87332f45
>            <idle>-0       [000] d.s2.  1719.521901: my_direct_func: ip
> ffffffff87332f45
>       rcu_preempt-15      [001] .....  1719.521917: my_direct_func: ip
> ffffffff8828d935
> [...]
>
> The ip values are wake_up_process+0x5 and schedule+0x5, the locations
> where the execution of the traced functions resumes after the Ftrace
> trampoline has finished.
>
> The results with ftrace-direct-multi-modify.ko are similar to that.
>
> The samples look like a demonstration, that one can pass anything
> necessary to the handler in case of "direct" functions.
>
> I suppose, the RISC-V-specific asm code in these two sample modules
> could be updated to pass the saved pc value to my_direct_func() in a0.

Yes, you're right.

I added 'mv a0,t0' in front of `call my_direct_func` to pass the address of
traced function with mcount offset.

Here is the updated patch for your reference.
https://github.com/sugarfillet/linux/commit/95b174fb104dd970b982ee6fa19879393e229318


>
> >
> >>
> >> As for this patch, it just impls a simple mcount (direct_caller) to
> >> trace kernel functions, and basically saves the necessary ABI,
> >> call the tracing function, and restores the ABI, just like other
> >> arches do.
> >> so It shouldn't be blamed.
> >>
> >> I started an independent patch to replace schedule with kick_process
> >> to make these samples more reasonable. And It has no conflict with the
> >> current patch, so we can go on.
> >>
> >> Link:
> >> https://lore.kernel.org/linux-kernel/20230117091101.3669996-1-suagrfillet@gmail.com/T/#u
> >>
> >>> The same issue is with ftrace-direct-multi-modify.ko.
> >>>
> >>> Is anything missing here?
> >>>
> >>>>
> >>>> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> >>>> index 307a9f413edd..e944af44f681 100644
> >>>> --- a/arch/riscv/Kconfig
> >>>> +++ b/arch/riscv/Kconfig
> >>>> @@ -112,6 +112,8 @@ config RISCV
> >>>>           select HAVE_POSIX_CPU_TIMERS_TASK_WORK
> >>>>           select HAVE_REGS_AND_STACK_ACCESS_API
> >>>>           select HAVE_FUNCTION_ARG_ACCESS_API
> >>>> +       select HAVE_SAMPLE_FTRACE_DIRECT
> >>>> +       select HAVE_SAMPLE_FTRACE_DIRECT_MULTI
> >>>>           select HAVE_STACKPROTECTOR
> >>>>           select HAVE_SYSCALL_TRACEPOINTS
> >>>>           select HAVE_RSEQ
> >>>> diff --git a/samples/ftrace/ftrace-direct-modify.c
> >>>> b/samples/ftrace/ftrace-direct-modify.c
> >>>> index de5a0f67f320..be7bf472c3c7 100644
> >>>> --- a/samples/ftrace/ftrace-direct-modify.c
> >>>> +++ b/samples/ftrace/ftrace-direct-modify.c
> >>>> @@ -23,6 +23,39 @@ extern void my_tramp2(void *);
> >>>>
> >>>>    static unsigned long my_ip = (unsigned long)schedule;
> >>>>
> >>>> +#ifdef CONFIG_RISCV
> >>>> +
> >>>> +asm (" .pushsection    .text, \"ax\", @progbits\n"
> >>>> +"      .type           my_tramp1, @function\n"
> >>>> +"      .globl          my_tramp1\n"
> >>>> +"   my_tramp1:\n"
> >>>> +"      addi sp,sp,-16\n"
> >>>> +"      sd   t0,0(sp)\n"
> >>>> +"      sd   ra,8(sp)\n"
> >>>> +"      call my_direct_func1\n"
> >>>> +"      ld   t0,0(sp)\n"
> >>>> +"      ld   ra,8(sp)\n"
> >>>> +"      addi sp,sp,16\n"
> >>>> +"      jr t0\n"
> >>>> +"      .size           my_tramp1, .-my_tramp1\n"
> >>>> +
> >>>> +"      .type           my_tramp2, @function\n"
> >>>> +"      .globl          my_tramp2\n"
> >>>> +"   my_tramp2:\n"
> >>>> +"      addi sp,sp,-16\n"
> >>>> +"      sd   t0,0(sp)\n"
> >>>> +"      sd   ra,8(sp)\n"
> >>>> +"      call my_direct_func2\n"
> >>>> +"      ld   t0,0(sp)\n"
> >>>> +"      ld   ra,8(sp)\n"
> >>>> +"      addi sp,sp,16\n"
> >>>> +"      jr t0\n"
> >>>> +"      .size           my_tramp2, .-my_tramp2\n"
> >>>> +"      .popsection\n"
> >>>> +);
> >>>> +
> >>>> +#endif /* CONFIG_RISCV */
> >>>> +
> >>>>    #ifdef CONFIG_X86_64
> >>>>
> >>>>    #include <asm/ibt.h>
> >>>> diff --git a/samples/ftrace/ftrace-direct-multi-modify.c
> >>>> b/samples/ftrace/ftrace-direct-multi-modify.c
> >>>> index d52370cad0b6..10884bf418f7 100644
> >>>> --- a/samples/ftrace/ftrace-direct-multi-modify.c
> >>>> +++ b/samples/ftrace/ftrace-direct-multi-modify.c
> >>>> @@ -21,6 +21,43 @@ void my_direct_func2(unsigned long ip)
> >>>>    extern void my_tramp1(void *);
> >>>>    extern void my_tramp2(void *);
> >>>>
> >>>> +#ifdef CONFIG_RISCV
> >>>> +
> >>>> +asm (" .pushsection    .text, \"ax\", @progbits\n"
> >>>> +"      .type           my_tramp1, @function\n"
> >>>> +"      .globl          my_tramp1\n"
> >>>> +"   my_tramp1:\n"
> >>>> +"       addi sp,sp,-24\n"
> >>>> +"       sd   a0,0(sp)\n"
> >>>> +"       sd   t0,8(sp)\n"
> >>>> +"       sd   ra,16(sp)\n"
> >>>> +"       call my_direct_func1\n"
> >>>> +"       ld   a0,0(sp)\n"
> >>>> +"       ld   t0,8(sp)\n"
> >>>> +"       ld   ra,16(sp)\n"
> >>>> +"       addi sp,sp,24\n"
> >>>> +"      jr t0\n"
> >>>> +"      .size           my_tramp1, .-my_tramp1\n"
> >>>> +
> >>>> +"      .type           my_tramp2, @function\n"
> >>>> +"      .globl          my_tramp2\n"
> >>>> +"   my_tramp2:\n"
> >>>> +"       addi sp,sp,-24\n"
> >>>> +"       sd   a0,0(sp)\n"
> >>>> +"       sd   t0,8(sp)\n"
> >>>> +"       sd   ra,16(sp)\n"
> >>>> +"       call my_direct_func2\n"
> >>>> +"       ld   a0,0(sp)\n"
> >>>> +"       ld   t0,8(sp)\n"
> >>>> +"       ld   ra,16(sp)\n"
> >>>> +"       addi sp,sp,24\n"
> >>>> +"      jr t0\n"
> >>>> +"      .size           my_tramp2, .-my_tramp2\n"
> >>>> +"      .popsection\n"
> >>>> +);
> >>>> +
> >>>> +#endif /* CONFIG_RISCV */
> >>>> +
> >>>>    #ifdef CONFIG_X86_64
> >>>>
> >>>>    #include <asm/ibt.h>
> >>>> diff --git a/samples/ftrace/ftrace-direct-multi.c
> >>>> b/samples/ftrace/ftrace-direct-multi.c
> >>>> index ec1088922517..a35bf43bf6d7 100644
> >>>> --- a/samples/ftrace/ftrace-direct-multi.c
> >>>> +++ b/samples/ftrace/ftrace-direct-multi.c
> >>>> @@ -16,6 +16,28 @@ void my_direct_func(unsigned long ip)
> >>>>
> >>>>    extern void my_tramp(void *);
> >>>>
> >>>> +#ifdef CONFIG_RISCV
> >>>> +
> >>>> +asm ("       .pushsection    .text, \"ax\", @progbits\n"
> >>>> +"       .type           my_tramp, @function\n"
> >>>> +"       .globl          my_tramp\n"
> >>>> +"   my_tramp:\n"
> >>>> +"       addi sp,sp,-24\n"
> >>>> +"       sd   a0,0(sp)\n"
> >>>> +"       sd   t0,8(sp)\n"
> >>>> +"       sd   ra,16(sp)\n"
> >>>> +"       call my_direct_func\n"
> >>>> +"       ld   a0,0(sp)\n"
> >>>> +"       ld   t0,8(sp)\n"
> >>>> +"       ld   ra,16(sp)\n"
> >>>> +"       addi sp,sp,24\n"
> >>>> +"       jr t0\n"
> >>>> +"       .size           my_tramp, .-my_tramp\n"
> >>>> +"       .popsection\n"
> >>>> +);
> >>>> +
> >>>> +#endif /* CONFIG_RISCV */
> >>>> +
> >>>>    #ifdef CONFIG_X86_64
> >>>>
> >>>>    #include <asm/ibt.h>
> >>>> diff --git a/samples/ftrace/ftrace-direct-too.c
> >>>> b/samples/ftrace/ftrace-direct-too.c
> >>>> index e13fb59a2b47..3b62e33c2e6d 100644
> >>>> --- a/samples/ftrace/ftrace-direct-too.c
> >>>> +++ b/samples/ftrace/ftrace-direct-too.c
> >>>> @@ -18,6 +18,32 @@ void my_direct_func(struct vm_area_struct *vma,
> >>>>
> >>>>    extern void my_tramp(void *);
> >>>>
> >>>> +#ifdef CONFIG_RISCV
> >>>> +
> >>>> +asm ("       .pushsection    .text, \"ax\", @progbits\n"
> >>>> +"       .type           my_tramp, @function\n"
> >>>> +"       .globl          my_tramp\n"
> >>>> +"   my_tramp:\n"
> >>>> +"       addi sp,sp,-40\n"
> >>>> +"       sd   a0,0(sp)\n"
> >>>> +"       sd   a1,8(sp)\n"
> >>>> +"       sd   a2,16(sp)\n"
> >>>> +"       sd   t0,24(sp)\n"
> >>>> +"       sd   ra,32(sp)\n"
> >>>> +"       call my_direct_func\n"
> >>>> +"       ld   a0,0(sp)\n"
> >>>> +"       ld   a1,8(sp)\n"
> >>>> +"       ld   a2,16(sp)\n"
> >>>> +"       ld   t0,24(sp)\n"
> >>>> +"       ld   ra,32(sp)\n"
> >>>> +"       addi sp,sp,40\n"
> >>>> +"       jr t0\n"
> >>>> +"       .size           my_tramp, .-my_tramp\n"
> >>>> +"       .popsection\n"
> >>>> +);
> >>>> +
> >>>> +#endif /* CONFIG_RISCV */
> >>>> +
> >>>>    #ifdef CONFIG_X86_64
> >>>>
> >>>>    #include <asm/ibt.h>
> >>>> diff --git a/samples/ftrace/ftrace-direct.c
> >>>> b/samples/ftrace/ftrace-direct.c
> >>>> index 1f769d0db20f..2cfe5a7d2d70 100644
> >>>> --- a/samples/ftrace/ftrace-direct.c
> >>>> +++ b/samples/ftrace/ftrace-direct.c
> >>>> @@ -15,6 +15,28 @@ void my_direct_func(struct task_struct *p)
> >>>>
> >>>>    extern void my_tramp(void *);
> >>>>
> >>>> +#ifdef CONFIG_RISCV
> >>>> +
> >>>> +asm ("       .pushsection    .text, \"ax\", @progbits\n"
> >>>> +"       .type           my_tramp, @function\n"
> >>>> +"       .globl          my_tramp\n"
> >>>> +"   my_tramp:\n"
> >>>> +"       addi sp,sp,-24\n"
> >>>> +"       sd   a0,0(sp)\n"
> >>>> +"       sd   t0,8(sp)\n"
> >>>> +"       sd   ra,16(sp)\n"
> >>>> +"       call my_direct_func\n"
> >>>> +"       ld   a0,0(sp)\n"
> >>>> +"       ld   t0,8(sp)\n"
> >>>> +"       ld   ra,16(sp)\n"
> >>>> +"       addi sp,sp,24\n"
> >>>> +"       jr t0\n"
> >>>> +"       .size           my_tramp, .-my_tramp\n"
> >>>> +"       .popsection\n"
> >>>> +);
> >>>> +
> >>>> +#endif /* CONFIG_RISCV */
> >>>> +
> >>>>    #ifdef CONFIG_X86_64
> >>>>
> >>>>    #include <asm/ibt.h>
> >>>> --
> >>>> 2.36.1
> >>
> >> --
> >> Thanks,
> >> Song
> >>
> >
> > Regards,
> > Evgenii
>
>
  

On 18.01.2023 05:37, Song Shuai wrote:
> Evgenii Shatokhin <e.shatokhin@yadro.com> 于2023年1月17日周二 16:22写道：
>>
>> On 17.01.2023 16:16, Evgenii Shatokhin wrote:
>>> Hi, Song,
>>>
>>> On 17.01.2023 12:32, Song Shuai wrote:
>>>>
>>>> Hi, Evgenii:
>>>>
>>>> Evgenii Shatokhin <e.shatokhin@yadro.com> 于2023年1月16日周一 14:30写道：
>>>>
>>>>>
>>>>> Hi,
>>>>>
>>>>> On 12.01.2023 12:06, guoren@kernel.org wrote:
>>>>>> From: Song Shuai <suagrfillet@gmail.com>
>>>>>>
>>>>>> select HAVE_SAMPLE_FTRACE_DIRECT and HAVE_SAMPLE_FTRACE_DIRECT_MULTI
>>>>>> for ARCH_RV64I in arch/riscv/Kconfig. And add riscv asm code for
>>>>>> the ftrace-direct*.c files in samples/ftrace/.
>>>>>>
>>>>>> Signed-off-by: Song Shuai <suagrfillet@gmail.com>
>>>>>> Tested-by: Guo Ren <guoren@kernel.org>
>>>>>> Signed-off-by: Guo Ren <guoren@kernel.org>
>>>>>> ---
>>>>>>     arch/riscv/Kconfig                          |  2 ++
>>>>>>     samples/ftrace/ftrace-direct-modify.c       | 33 ++++++++++++++++++
>>>>>>     samples/ftrace/ftrace-direct-multi-modify.c | 37
>>>>>> +++++++++++++++++++++
>>>>>>     samples/ftrace/ftrace-direct-multi.c        | 22 ++++++++++++
>>>>>>     samples/ftrace/ftrace-direct-too.c          | 26 +++++++++++++++
>>>>>>     samples/ftrace/ftrace-direct.c              | 22 ++++++++++++
>>>>>>     6 files changed, 142 insertions(+)
>>>>>
>>>>> The samples were built OK now, but ftrace-direct-multi and
>>>>> ftrace-direct-multi-modify report incorrect values of ip/pc it seems.
>>>>>
>>>>> I ran 'insmod ftrace-direct-multi.ko', waited a little and then checked
>>>>> the messages in the trace:
>>>>>
>>>>> #           TASK-PID     CPU#  |||||  TIMESTAMP  FUNCTION
>>>>> #              | |         |   |||||     |         |
>>>>>         migration/1-19      [001] .....  3858.532131: my_direct_func1: my
>>>>> direct func1 ip 0
>>>>>         migration/0-15      [000] d.s2.  3858.532136: my_direct_func1: my
>>>>> direct func1 ip ff60000001ba9600
>>>>>         migration/0-15      [000] d..2.  3858.532204: my_direct_func1: my
>>>>> direct func1 ip ff60000003334d00
>>>>>         migration/0-15      [000] .....  3858.532232: my_direct_func1: my
>>>>> direct func1 ip 0
>>>>>           rcu_sched-14      [001] .....  3858.532257: my_direct_func1: my
>>>>> direct func1 ip 0
>>>>>              insmod-415     [000] .....  3858.532270: my_direct_func1: my
>>>>> direct func1 ip 7fffffffffffffff
>>>>>              <idle>-0       [001] ..s1.  3858.539051: my_direct_func1: my
>>>>> direct func1 ip ff60000001ba9600
>>>>>              <idle>-0       [001] dns2.  3858.539124: my_direct_func1: my
>>>>> direct func1 ip ff60000001ba9600
>>>>>           rcu_sched-14      [001] .....  3858.539208: my_direct_func1: my
>>>>> direct func1 ip 0
>>>>> [...]
>>>>>
>>>>> If I understand it right, my_direct_func1() should print the address of
>>>>> some location in the code, probably - at the beginning of the traced
>>>>> functions.
>>>>>
>>>>> The printed values (0x0, 0x7fffffffffffffff, ...) are not valid code
>>>>> addresses.
>>>>>
>>>> The invalid code address is only printed by accessing the schedule()
>>>> function's first argument whose address stores in a0 register.
>>>> While schedule() actually has no parameter declared, so my_direct_func
>>>> just prints the a0 in the context of the schedule()'s caller and
>>>> the address maybe varies depending on the caller.
>>>>
>>>> I can't really understand why tracing the first argument of the
>>>> schedule() function, but it seems nonsense at this point.
>>>
>>> The question is, what should be passed as the argument(s) of
>>> my_direct_func() in this particular sample module. The kernel docs and
>>> commit logs seem to contain no info on that.
>>>
>>> With direct functions, I suppose, the trampoline can pass anything it
>>> wants to my_direct_func(), not just the arguments of the traced function.
>>>
>>> I'd check what these sample modules do on x86 and would try to match
>>> that behaviour on RISC-V.
>>
>> I have checked ftrace-direct-multi.ko and ftrace-direct-multi-modify.ko
>> on 6.2-rc4 built for x86-64 - yes, ip/pc in the traced function should
>> be passed to my_direct_func().
>>
>> ftrace-direct-multi.ko:
>> #           TASK-PID     CPU#  |||||  TIMESTAMP  FUNCTION
>> #              | |         |   |||||     |         |
>>             insmod-10829   [000] d.h1.  1719.518535: my_direct_func: ip
>> ffffffff87332f45 // wake_up_process+0x5
>>    rcu_tasks_kthre-11      [000] .....  1719.518696: my_direct_func: ip
>> ffffffff8828d935 // schedule+0x5
>>             insmod-10829   [000] .....  1719.518708: my_direct_func: ip
>> ffffffff8828d935
>>    systemd-journal-293     [001] .....  1719.518823: my_direct_func: ip
>> ffffffff8828d935
>>            systemd-1       [000] .....  1719.519141: my_direct_func: ip
>> ffffffff8828d935
>>             <idle>-0       [001] ..s1.  1719.521889: my_direct_func: ip
>> ffffffff87332f45
>>             <idle>-0       [000] d.s2.  1719.521901: my_direct_func: ip
>> ffffffff87332f45
>>        rcu_preempt-15      [001] .....  1719.521917: my_direct_func: ip
>> ffffffff8828d935
>> [...]
>>
>> The ip values are wake_up_process+0x5 and schedule+0x5, the locations
>> where the execution of the traced functions resumes after the Ftrace
>> trampoline has finished.
>>
>> The results with ftrace-direct-multi-modify.ko are similar to that.
>>
>> The samples look like a demonstration, that one can pass anything
>> necessary to the handler in case of "direct" functions.
>>
>> I suppose, the RISC-V-specific asm code in these two sample modules
>> could be updated to pass the saved pc value to my_direct_func() in a0.
> 
> Yes, you're right.
> 
> I added 'mv a0,t0' in front of `call my_direct_func` to pass the address of
> traced function with mcount offset.
> 
> Here is the updated patch for your reference.
> https://github.com/sugarfillet/linux/commit/95b174fb104dd970b982ee6fa19879393e229318

Thank you for the quick fix. This one looks good to me.

ftrace-direct-multi*.ko now report the ip values corresponding to 
schedule+0x8 and wake_up_process+0x8, which is what was expected here.

One more thing: please change my "Co-developed-by:" into "Tested-by:" in 
your patch, becase this is what I actually did: tested it and reported 
the results. I cannot take your credit for development of this patch ;-)

Looking forward for v8 of the series.
> 
> 
>>
>>>
>>>>
>>>> As for this patch, it just impls a simple mcount (direct_caller) to
>>>> trace kernel functions, and basically saves the necessary ABI,
>>>> call the tracing function, and restores the ABI, just like other
>>>> arches do.
>>>> so It shouldn't be blamed.
>>>>
>>>> I started an independent patch to replace schedule with kick_process
>>>> to make these samples more reasonable. And It has no conflict with the
>>>> current patch, so we can go on.
>>>>
>>>> Link:
>>>> https://lore.kernel.org/linux-kernel/20230117091101.3669996-1-suagrfillet@gmail.com/T/#u
>>>>
>>>>> The same issue is with ftrace-direct-multi-modify.ko.
>>>>>
>>>>> Is anything missing here?
>>>>>
>>>>>>
>>>>>> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
>>>>>> index 307a9f413edd..e944af44f681 100644
>>>>>> --- a/arch/riscv/Kconfig
>>>>>> +++ b/arch/riscv/Kconfig
>>>>>> @@ -112,6 +112,8 @@ config RISCV
>>>>>>            select HAVE_POSIX_CPU_TIMERS_TASK_WORK
>>>>>>            select HAVE_REGS_AND_STACK_ACCESS_API
>>>>>>            select HAVE_FUNCTION_ARG_ACCESS_API
>>>>>> +       select HAVE_SAMPLE_FTRACE_DIRECT
>>>>>> +       select HAVE_SAMPLE_FTRACE_DIRECT_MULTI
>>>>>>            select HAVE_STACKPROTECTOR
>>>>>>            select HAVE_SYSCALL_TRACEPOINTS
>>>>>>            select HAVE_RSEQ
>>>>>> diff --git a/samples/ftrace/ftrace-direct-modify.c
>>>>>> b/samples/ftrace/ftrace-direct-modify.c
>>>>>> index de5a0f67f320..be7bf472c3c7 100644
>>>>>> --- a/samples/ftrace/ftrace-direct-modify.c
>>>>>> +++ b/samples/ftrace/ftrace-direct-modify.c
>>>>>> @@ -23,6 +23,39 @@ extern void my_tramp2(void *);
>>>>>>
>>>>>>     static unsigned long my_ip = (unsigned long)schedule;
>>>>>>
>>>>>> +#ifdef CONFIG_RISCV
>>>>>> +
>>>>>> +asm (" .pushsection    .text, \"ax\", @progbits\n"
>>>>>> +"      .type           my_tramp1, @function\n"
>>>>>> +"      .globl          my_tramp1\n"
>>>>>> +"   my_tramp1:\n"
>>>>>> +"      addi sp,sp,-16\n"
>>>>>> +"      sd   t0,0(sp)\n"
>>>>>> +"      sd   ra,8(sp)\n"
>>>>>> +"      call my_direct_func1\n"
>>>>>> +"      ld   t0,0(sp)\n"
>>>>>> +"      ld   ra,8(sp)\n"
>>>>>> +"      addi sp,sp,16\n"
>>>>>> +"      jr t0\n"
>>>>>> +"      .size           my_tramp1, .-my_tramp1\n"
>>>>>> +
>>>>>> +"      .type           my_tramp2, @function\n"
>>>>>> +"      .globl          my_tramp2\n"
>>>>>> +"   my_tramp2:\n"
>>>>>> +"      addi sp,sp,-16\n"
>>>>>> +"      sd   t0,0(sp)\n"
>>>>>> +"      sd   ra,8(sp)\n"
>>>>>> +"      call my_direct_func2\n"
>>>>>> +"      ld   t0,0(sp)\n"
>>>>>> +"      ld   ra,8(sp)\n"
>>>>>> +"      addi sp,sp,16\n"
>>>>>> +"      jr t0\n"
>>>>>> +"      .size           my_tramp2, .-my_tramp2\n"
>>>>>> +"      .popsection\n"
>>>>>> +);
>>>>>> +
>>>>>> +#endif /* CONFIG_RISCV */
>>>>>> +
>>>>>>     #ifdef CONFIG_X86_64
>>>>>>
>>>>>>     #include <asm/ibt.h>
>>>>>> diff --git a/samples/ftrace/ftrace-direct-multi-modify.c
>>>>>> b/samples/ftrace/ftrace-direct-multi-modify.c
>>>>>> index d52370cad0b6..10884bf418f7 100644
>>>>>> --- a/samples/ftrace/ftrace-direct-multi-modify.c
>>>>>> +++ b/samples/ftrace/ftrace-direct-multi-modify.c
>>>>>> @@ -21,6 +21,43 @@ void my_direct_func2(unsigned long ip)
>>>>>>     extern void my_tramp1(void *);
>>>>>>     extern void my_tramp2(void *);
>>>>>>
>>>>>> +#ifdef CONFIG_RISCV
>>>>>> +
>>>>>> +asm (" .pushsection    .text, \"ax\", @progbits\n"
>>>>>> +"      .type           my_tramp1, @function\n"
>>>>>> +"      .globl          my_tramp1\n"
>>>>>> +"   my_tramp1:\n"
>>>>>> +"       addi sp,sp,-24\n"
>>>>>> +"       sd   a0,0(sp)\n"
>>>>>> +"       sd   t0,8(sp)\n"
>>>>>> +"       sd   ra,16(sp)\n"
>>>>>> +"       call my_direct_func1\n"
>>>>>> +"       ld   a0,0(sp)\n"
>>>>>> +"       ld   t0,8(sp)\n"
>>>>>> +"       ld   ra,16(sp)\n"
>>>>>> +"       addi sp,sp,24\n"
>>>>>> +"      jr t0\n"
>>>>>> +"      .size           my_tramp1, .-my_tramp1\n"
>>>>>> +
>>>>>> +"      .type           my_tramp2, @function\n"
>>>>>> +"      .globl          my_tramp2\n"
>>>>>> +"   my_tramp2:\n"
>>>>>> +"       addi sp,sp,-24\n"
>>>>>> +"       sd   a0,0(sp)\n"
>>>>>> +"       sd   t0,8(sp)\n"
>>>>>> +"       sd   ra,16(sp)\n"
>>>>>> +"       call my_direct_func2\n"
>>>>>> +"       ld   a0,0(sp)\n"
>>>>>> +"       ld   t0,8(sp)\n"
>>>>>> +"       ld   ra,16(sp)\n"
>>>>>> +"       addi sp,sp,24\n"
>>>>>> +"      jr t0\n"
>>>>>> +"      .size           my_tramp2, .-my_tramp2\n"
>>>>>> +"      .popsection\n"
>>>>>> +);
>>>>>> +
>>>>>> +#endif /* CONFIG_RISCV */
>>>>>> +
>>>>>>     #ifdef CONFIG_X86_64
>>>>>>
>>>>>>     #include <asm/ibt.h>
>>>>>> diff --git a/samples/ftrace/ftrace-direct-multi.c
>>>>>> b/samples/ftrace/ftrace-direct-multi.c
>>>>>> index ec1088922517..a35bf43bf6d7 100644
>>>>>> --- a/samples/ftrace/ftrace-direct-multi.c
>>>>>> +++ b/samples/ftrace/ftrace-direct-multi.c
>>>>>> @@ -16,6 +16,28 @@ void my_direct_func(unsigned long ip)
>>>>>>
>>>>>>     extern void my_tramp(void *);
>>>>>>
>>>>>> +#ifdef CONFIG_RISCV
>>>>>> +
>>>>>> +asm ("       .pushsection    .text, \"ax\", @progbits\n"
>>>>>> +"       .type           my_tramp, @function\n"
>>>>>> +"       .globl          my_tramp\n"
>>>>>> +"   my_tramp:\n"
>>>>>> +"       addi sp,sp,-24\n"
>>>>>> +"       sd   a0,0(sp)\n"
>>>>>> +"       sd   t0,8(sp)\n"
>>>>>> +"       sd   ra,16(sp)\n"
>>>>>> +"       call my_direct_func\n"
>>>>>> +"       ld   a0,0(sp)\n"
>>>>>> +"       ld   t0,8(sp)\n"
>>>>>> +"       ld   ra,16(sp)\n"
>>>>>> +"       addi sp,sp,24\n"
>>>>>> +"       jr t0\n"
>>>>>> +"       .size           my_tramp, .-my_tramp\n"
>>>>>> +"       .popsection\n"
>>>>>> +);
>>>>>> +
>>>>>> +#endif /* CONFIG_RISCV */
>>>>>> +
>>>>>>     #ifdef CONFIG_X86_64
>>>>>>
>>>>>>     #include <asm/ibt.h>
>>>>>> diff --git a/samples/ftrace/ftrace-direct-too.c
>>>>>> b/samples/ftrace/ftrace-direct-too.c
>>>>>> index e13fb59a2b47..3b62e33c2e6d 100644
>>>>>> --- a/samples/ftrace/ftrace-direct-too.c
>>>>>> +++ b/samples/ftrace/ftrace-direct-too.c
>>>>>> @@ -18,6 +18,32 @@ void my_direct_func(struct vm_area_struct *vma,
>>>>>>
>>>>>>     extern void my_tramp(void *);
>>>>>>
>>>>>> +#ifdef CONFIG_RISCV
>>>>>> +
>>>>>> +asm ("       .pushsection    .text, \"ax\", @progbits\n"
>>>>>> +"       .type           my_tramp, @function\n"
>>>>>> +"       .globl          my_tramp\n"
>>>>>> +"   my_tramp:\n"
>>>>>> +"       addi sp,sp,-40\n"
>>>>>> +"       sd   a0,0(sp)\n"
>>>>>> +"       sd   a1,8(sp)\n"
>>>>>> +"       sd   a2,16(sp)\n"
>>>>>> +"       sd   t0,24(sp)\n"
>>>>>> +"       sd   ra,32(sp)\n"
>>>>>> +"       call my_direct_func\n"
>>>>>> +"       ld   a0,0(sp)\n"
>>>>>> +"       ld   a1,8(sp)\n"
>>>>>> +"       ld   a2,16(sp)\n"
>>>>>> +"       ld   t0,24(sp)\n"
>>>>>> +"       ld   ra,32(sp)\n"
>>>>>> +"       addi sp,sp,40\n"
>>>>>> +"       jr t0\n"
>>>>>> +"       .size           my_tramp, .-my_tramp\n"
>>>>>> +"       .popsection\n"
>>>>>> +);
>>>>>> +
>>>>>> +#endif /* CONFIG_RISCV */
>>>>>> +
>>>>>>     #ifdef CONFIG_X86_64
>>>>>>
>>>>>>     #include <asm/ibt.h>
>>>>>> diff --git a/samples/ftrace/ftrace-direct.c
>>>>>> b/samples/ftrace/ftrace-direct.c
>>>>>> index 1f769d0db20f..2cfe5a7d2d70 100644
>>>>>> --- a/samples/ftrace/ftrace-direct.c
>>>>>> +++ b/samples/ftrace/ftrace-direct.c
>>>>>> @@ -15,6 +15,28 @@ void my_direct_func(struct task_struct *p)
>>>>>>
>>>>>>     extern void my_tramp(void *);
>>>>>>
>>>>>> +#ifdef CONFIG_RISCV
>>>>>> +
>>>>>> +asm ("       .pushsection    .text, \"ax\", @progbits\n"
>>>>>> +"       .type           my_tramp, @function\n"
>>>>>> +"       .globl          my_tramp\n"
>>>>>> +"   my_tramp:\n"
>>>>>> +"       addi sp,sp,-24\n"
>>>>>> +"       sd   a0,0(sp)\n"
>>>>>> +"       sd   t0,8(sp)\n"
>>>>>> +"       sd   ra,16(sp)\n"
>>>>>> +"       call my_direct_func\n"
>>>>>> +"       ld   a0,0(sp)\n"
>>>>>> +"       ld   t0,8(sp)\n"
>>>>>> +"       ld   ra,16(sp)\n"
>>>>>> +"       addi sp,sp,24\n"
>>>>>> +"       jr t0\n"
>>>>>> +"       .size           my_tramp, .-my_tramp\n"
>>>>>> +"       .popsection\n"
>>>>>> +);
>>>>>> +
>>>>>> +#endif /* CONFIG_RISCV */
>>>>>> +
>>>>>>     #ifdef CONFIG_X86_64
>>>>>>
>>>>>>     #include <asm/ibt.h>
>>>>>> --
>>>>>> 2.36.1
>>>>
>>>> --
>>>> Thanks,
>>>> Song
>>>>
>>>
>>> Regards,
>>> Evgenii
>>
>>
> 
> 
> --
> Thanks,
> Song
>
  

Thx Evgenii & Song,

I got it; it would be put into v8.

On Wed, Jan 18, 2023 at 11:19 PM Evgenii Shatokhin
<e.shatokhin@yadro.com> wrote:
>
> On 18.01.2023 05:37, Song Shuai wrote:
> > Evgenii Shatokhin <e.shatokhin@yadro.com> 于2023年1月17日周二 16:22写道：
> >>
> >> On 17.01.2023 16:16, Evgenii Shatokhin wrote:
> >>> Hi, Song,
> >>>
> >>> On 17.01.2023 12:32, Song Shuai wrote:
> >>>>
> >>>> Hi, Evgenii:
> >>>>
> >>>> Evgenii Shatokhin <e.shatokhin@yadro.com> 于2023年1月16日周一 14:30写道：
> >>>>
> >>>>>
> >>>>> Hi,
> >>>>>
> >>>>> On 12.01.2023 12:06, guoren@kernel.org wrote:
> >>>>>> From: Song Shuai <suagrfillet@gmail.com>
> >>>>>>
> >>>>>> select HAVE_SAMPLE_FTRACE_DIRECT and HAVE_SAMPLE_FTRACE_DIRECT_MULTI
> >>>>>> for ARCH_RV64I in arch/riscv/Kconfig. And add riscv asm code for
> >>>>>> the ftrace-direct*.c files in samples/ftrace/.
> >>>>>>
> >>>>>> Signed-off-by: Song Shuai <suagrfillet@gmail.com>
> >>>>>> Tested-by: Guo Ren <guoren@kernel.org>
> >>>>>> Signed-off-by: Guo Ren <guoren@kernel.org>
> >>>>>> ---
> >>>>>>     arch/riscv/Kconfig                          |  2 ++
> >>>>>>     samples/ftrace/ftrace-direct-modify.c       | 33 ++++++++++++++++++
> >>>>>>     samples/ftrace/ftrace-direct-multi-modify.c | 37
> >>>>>> +++++++++++++++++++++
> >>>>>>     samples/ftrace/ftrace-direct-multi.c        | 22 ++++++++++++
> >>>>>>     samples/ftrace/ftrace-direct-too.c          | 26 +++++++++++++++
> >>>>>>     samples/ftrace/ftrace-direct.c              | 22 ++++++++++++
> >>>>>>     6 files changed, 142 insertions(+)
> >>>>>
> >>>>> The samples were built OK now, but ftrace-direct-multi and
> >>>>> ftrace-direct-multi-modify report incorrect values of ip/pc it seems.
> >>>>>
> >>>>> I ran 'insmod ftrace-direct-multi.ko', waited a little and then checked
> >>>>> the messages in the trace:
> >>>>>
> >>>>> #           TASK-PID     CPU#  |||||  TIMESTAMP  FUNCTION
> >>>>> #              | |         |   |||||     |         |
> >>>>>         migration/1-19      [001] .....  3858.532131: my_direct_func1: my
> >>>>> direct func1 ip 0
> >>>>>         migration/0-15      [000] d.s2.  3858.532136: my_direct_func1: my
> >>>>> direct func1 ip ff60000001ba9600
> >>>>>         migration/0-15      [000] d..2.  3858.532204: my_direct_func1: my
> >>>>> direct func1 ip ff60000003334d00
> >>>>>         migration/0-15      [000] .....  3858.532232: my_direct_func1: my
> >>>>> direct func1 ip 0
> >>>>>           rcu_sched-14      [001] .....  3858.532257: my_direct_func1: my
> >>>>> direct func1 ip 0
> >>>>>              insmod-415     [000] .....  3858.532270: my_direct_func1: my
> >>>>> direct func1 ip 7fffffffffffffff
> >>>>>              <idle>-0       [001] ..s1.  3858.539051: my_direct_func1: my
> >>>>> direct func1 ip ff60000001ba9600
> >>>>>              <idle>-0       [001] dns2.  3858.539124: my_direct_func1: my
> >>>>> direct func1 ip ff60000001ba9600
> >>>>>           rcu_sched-14      [001] .....  3858.539208: my_direct_func1: my
> >>>>> direct func1 ip 0
> >>>>> [...]
> >>>>>
> >>>>> If I understand it right, my_direct_func1() should print the address of
> >>>>> some location in the code, probably - at the beginning of the traced
> >>>>> functions.
> >>>>>
> >>>>> The printed values (0x0, 0x7fffffffffffffff, ...) are not valid code
> >>>>> addresses.
> >>>>>
> >>>> The invalid code address is only printed by accessing the schedule()
> >>>> function's first argument whose address stores in a0 register.
> >>>> While schedule() actually has no parameter declared, so my_direct_func
> >>>> just prints the a0 in the context of the schedule()'s caller and
> >>>> the address maybe varies depending on the caller.
> >>>>
> >>>> I can't really understand why tracing the first argument of the
> >>>> schedule() function, but it seems nonsense at this point.
> >>>
> >>> The question is, what should be passed as the argument(s) of
> >>> my_direct_func() in this particular sample module. The kernel docs and
> >>> commit logs seem to contain no info on that.
> >>>
> >>> With direct functions, I suppose, the trampoline can pass anything it
> >>> wants to my_direct_func(), not just the arguments of the traced function.
> >>>
> >>> I'd check what these sample modules do on x86 and would try to match
> >>> that behaviour on RISC-V.
> >>
> >> I have checked ftrace-direct-multi.ko and ftrace-direct-multi-modify.ko
> >> on 6.2-rc4 built for x86-64 - yes, ip/pc in the traced function should
> >> be passed to my_direct_func().
> >>
> >> ftrace-direct-multi.ko:
> >> #           TASK-PID     CPU#  |||||  TIMESTAMP  FUNCTION
> >> #              | |         |   |||||     |         |
> >>             insmod-10829   [000] d.h1.  1719.518535: my_direct_func: ip
> >> ffffffff87332f45 // wake_up_process+0x5
> >>    rcu_tasks_kthre-11      [000] .....  1719.518696: my_direct_func: ip
> >> ffffffff8828d935 // schedule+0x5
> >>             insmod-10829   [000] .....  1719.518708: my_direct_func: ip
> >> ffffffff8828d935
> >>    systemd-journal-293     [001] .....  1719.518823: my_direct_func: ip
> >> ffffffff8828d935
> >>            systemd-1       [000] .....  1719.519141: my_direct_func: ip
> >> ffffffff8828d935
> >>             <idle>-0       [001] ..s1.  1719.521889: my_direct_func: ip
> >> ffffffff87332f45
> >>             <idle>-0       [000] d.s2.  1719.521901: my_direct_func: ip
> >> ffffffff87332f45
> >>        rcu_preempt-15      [001] .....  1719.521917: my_direct_func: ip
> >> ffffffff8828d935
> >> [...]
> >>
> >> The ip values are wake_up_process+0x5 and schedule+0x5, the locations
> >> where the execution of the traced functions resumes after the Ftrace
> >> trampoline has finished.
> >>
> >> The results with ftrace-direct-multi-modify.ko are similar to that.
> >>
> >> The samples look like a demonstration, that one can pass anything
> >> necessary to the handler in case of "direct" functions.
> >>
> >> I suppose, the RISC-V-specific asm code in these two sample modules
> >> could be updated to pass the saved pc value to my_direct_func() in a0.
> >
> > Yes, you're right.
> >
> > I added 'mv a0,t0' in front of `call my_direct_func` to pass the address of
> > traced function with mcount offset.
> >
> > Here is the updated patch for your reference.
> > https://github.com/sugarfillet/linux/commit/95b174fb104dd970b982ee6fa19879393e229318
>
> Thank you for the quick fix. This one looks good to me.
>
> ftrace-direct-multi*.ko now report the ip values corresponding to
> schedule+0x8 and wake_up_process+0x8, which is what was expected here.
>
> One more thing: please change my "Co-developed-by:" into "Tested-by:" in
> your patch, becase this is what I actually did: tested it and reported
> the results. I cannot take your credit for development of this patch ;-)
>
> Looking forward for v8 of the series.
> >
> >
> >>
> >>>
> >>>>
> >>>> As for this patch, it just impls a simple mcount (direct_caller) to
> >>>> trace kernel functions, and basically saves the necessary ABI,
> >>>> call the tracing function, and restores the ABI, just like other
> >>>> arches do.
> >>>> so It shouldn't be blamed.
> >>>>
> >>>> I started an independent patch to replace schedule with kick_process
> >>>> to make these samples more reasonable. And It has no conflict with the
> >>>> current patch, so we can go on.
> >>>>
> >>>> Link:
> >>>> https://lore.kernel.org/linux-kernel/20230117091101.3669996-1-suagrfillet@gmail.com/T/#u
> >>>>
> >>>>> The same issue is with ftrace-direct-multi-modify.ko.
> >>>>>
> >>>>> Is anything missing here?
> >>>>>
> >>>>>>
> >>>>>> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> >>>>>> index 307a9f413edd..e944af44f681 100644
> >>>>>> --- a/arch/riscv/Kconfig
> >>>>>> +++ b/arch/riscv/Kconfig
> >>>>>> @@ -112,6 +112,8 @@ config RISCV
> >>>>>>            select HAVE_POSIX_CPU_TIMERS_TASK_WORK
> >>>>>>            select HAVE_REGS_AND_STACK_ACCESS_API
> >>>>>>            select HAVE_FUNCTION_ARG_ACCESS_API
> >>>>>> +       select HAVE_SAMPLE_FTRACE_DIRECT
> >>>>>> +       select HAVE_SAMPLE_FTRACE_DIRECT_MULTI
> >>>>>>            select HAVE_STACKPROTECTOR
> >>>>>>            select HAVE_SYSCALL_TRACEPOINTS
> >>>>>>            select HAVE_RSEQ
> >>>>>> diff --git a/samples/ftrace/ftrace-direct-modify.c
> >>>>>> b/samples/ftrace/ftrace-direct-modify.c
> >>>>>> index de5a0f67f320..be7bf472c3c7 100644
> >>>>>> --- a/samples/ftrace/ftrace-direct-modify.c
> >>>>>> +++ b/samples/ftrace/ftrace-direct-modify.c
> >>>>>> @@ -23,6 +23,39 @@ extern void my_tramp2(void *);
> >>>>>>
> >>>>>>     static unsigned long my_ip = (unsigned long)schedule;
> >>>>>>
> >>>>>> +#ifdef CONFIG_RISCV
> >>>>>> +
> >>>>>> +asm (" .pushsection    .text, \"ax\", @progbits\n"
> >>>>>> +"      .type           my_tramp1, @function\n"
> >>>>>> +"      .globl          my_tramp1\n"
> >>>>>> +"   my_tramp1:\n"
> >>>>>> +"      addi sp,sp,-16\n"
> >>>>>> +"      sd   t0,0(sp)\n"
> >>>>>> +"      sd   ra,8(sp)\n"
> >>>>>> +"      call my_direct_func1\n"
> >>>>>> +"      ld   t0,0(sp)\n"
> >>>>>> +"      ld   ra,8(sp)\n"
> >>>>>> +"      addi sp,sp,16\n"
> >>>>>> +"      jr t0\n"
> >>>>>> +"      .size           my_tramp1, .-my_tramp1\n"
> >>>>>> +
> >>>>>> +"      .type           my_tramp2, @function\n"
> >>>>>> +"      .globl          my_tramp2\n"
> >>>>>> +"   my_tramp2:\n"
> >>>>>> +"      addi sp,sp,-16\n"
> >>>>>> +"      sd   t0,0(sp)\n"
> >>>>>> +"      sd   ra,8(sp)\n"
> >>>>>> +"      call my_direct_func2\n"
> >>>>>> +"      ld   t0,0(sp)\n"
> >>>>>> +"      ld   ra,8(sp)\n"
> >>>>>> +"      addi sp,sp,16\n"
> >>>>>> +"      jr t0\n"
> >>>>>> +"      .size           my_tramp2, .-my_tramp2\n"
> >>>>>> +"      .popsection\n"
> >>>>>> +);
> >>>>>> +
> >>>>>> +#endif /* CONFIG_RISCV */
> >>>>>> +
> >>>>>>     #ifdef CONFIG_X86_64
> >>>>>>
> >>>>>>     #include <asm/ibt.h>
> >>>>>> diff --git a/samples/ftrace/ftrace-direct-multi-modify.c
> >>>>>> b/samples/ftrace/ftrace-direct-multi-modify.c
> >>>>>> index d52370cad0b6..10884bf418f7 100644
> >>>>>> --- a/samples/ftrace/ftrace-direct-multi-modify.c
> >>>>>> +++ b/samples/ftrace/ftrace-direct-multi-modify.c
> >>>>>> @@ -21,6 +21,43 @@ void my_direct_func2(unsigned long ip)
> >>>>>>     extern void my_tramp1(void *);
> >>>>>>     extern void my_tramp2(void *);
> >>>>>>
> >>>>>> +#ifdef CONFIG_RISCV
> >>>>>> +
> >>>>>> +asm (" .pushsection    .text, \"ax\", @progbits\n"
> >>>>>> +"      .type           my_tramp1, @function\n"
> >>>>>> +"      .globl          my_tramp1\n"
> >>>>>> +"   my_tramp1:\n"
> >>>>>> +"       addi sp,sp,-24\n"
> >>>>>> +"       sd   a0,0(sp)\n"
> >>>>>> +"       sd   t0,8(sp)\n"
> >>>>>> +"       sd   ra,16(sp)\n"
> >>>>>> +"       call my_direct_func1\n"
> >>>>>> +"       ld   a0,0(sp)\n"
> >>>>>> +"       ld   t0,8(sp)\n"
> >>>>>> +"       ld   ra,16(sp)\n"
> >>>>>> +"       addi sp,sp,24\n"
> >>>>>> +"      jr t0\n"
> >>>>>> +"      .size           my_tramp1, .-my_tramp1\n"
> >>>>>> +
> >>>>>> +"      .type           my_tramp2, @function\n"
> >>>>>> +"      .globl          my_tramp2\n"
> >>>>>> +"   my_tramp2:\n"
> >>>>>> +"       addi sp,sp,-24\n"
> >>>>>> +"       sd   a0,0(sp)\n"
> >>>>>> +"       sd   t0,8(sp)\n"
> >>>>>> +"       sd   ra,16(sp)\n"
> >>>>>> +"       call my_direct_func2\n"
> >>>>>> +"       ld   a0,0(sp)\n"
> >>>>>> +"       ld   t0,8(sp)\n"
> >>>>>> +"       ld   ra,16(sp)\n"
> >>>>>> +"       addi sp,sp,24\n"
> >>>>>> +"      jr t0\n"
> >>>>>> +"      .size           my_tramp2, .-my_tramp2\n"
> >>>>>> +"      .popsection\n"
> >>>>>> +);
> >>>>>> +
> >>>>>> +#endif /* CONFIG_RISCV */
> >>>>>> +
> >>>>>>     #ifdef CONFIG_X86_64
> >>>>>>
> >>>>>>     #include <asm/ibt.h>
> >>>>>> diff --git a/samples/ftrace/ftrace-direct-multi.c
> >>>>>> b/samples/ftrace/ftrace-direct-multi.c
> >>>>>> index ec1088922517..a35bf43bf6d7 100644
> >>>>>> --- a/samples/ftrace/ftrace-direct-multi.c
> >>>>>> +++ b/samples/ftrace/ftrace-direct-multi.c
> >>>>>> @@ -16,6 +16,28 @@ void my_direct_func(unsigned long ip)
> >>>>>>
> >>>>>>     extern void my_tramp(void *);
> >>>>>>
> >>>>>> +#ifdef CONFIG_RISCV
> >>>>>> +
> >>>>>> +asm ("       .pushsection    .text, \"ax\", @progbits\n"
> >>>>>> +"       .type           my_tramp, @function\n"
> >>>>>> +"       .globl          my_tramp\n"
> >>>>>> +"   my_tramp:\n"
> >>>>>> +"       addi sp,sp,-24\n"
> >>>>>> +"       sd   a0,0(sp)\n"
> >>>>>> +"       sd   t0,8(sp)\n"
> >>>>>> +"       sd   ra,16(sp)\n"
> >>>>>> +"       call my_direct_func\n"
> >>>>>> +"       ld   a0,0(sp)\n"
> >>>>>> +"       ld   t0,8(sp)\n"
> >>>>>> +"       ld   ra,16(sp)\n"
> >>>>>> +"       addi sp,sp,24\n"
> >>>>>> +"       jr t0\n"
> >>>>>> +"       .size           my_tramp, .-my_tramp\n"
> >>>>>> +"       .popsection\n"
> >>>>>> +);
> >>>>>> +
> >>>>>> +#endif /* CONFIG_RISCV */
> >>>>>> +
> >>>>>>     #ifdef CONFIG_X86_64
> >>>>>>
> >>>>>>     #include <asm/ibt.h>
> >>>>>> diff --git a/samples/ftrace/ftrace-direct-too.c
> >>>>>> b/samples/ftrace/ftrace-direct-too.c
> >>>>>> index e13fb59a2b47..3b62e33c2e6d 100644
> >>>>>> --- a/samples/ftrace/ftrace-direct-too.c
> >>>>>> +++ b/samples/ftrace/ftrace-direct-too.c
> >>>>>> @@ -18,6 +18,32 @@ void my_direct_func(struct vm_area_struct *vma,
> >>>>>>
> >>>>>>     extern void my_tramp(void *);
> >>>>>>
> >>>>>> +#ifdef CONFIG_RISCV
> >>>>>> +
> >>>>>> +asm ("       .pushsection    .text, \"ax\", @progbits\n"
> >>>>>> +"       .type           my_tramp, @function\n"
> >>>>>> +"       .globl          my_tramp\n"
> >>>>>> +"   my_tramp:\n"
> >>>>>> +"       addi sp,sp,-40\n"
> >>>>>> +"       sd   a0,0(sp)\n"
> >>>>>> +"       sd   a1,8(sp)\n"
> >>>>>> +"       sd   a2,16(sp)\n"
> >>>>>> +"       sd   t0,24(sp)\n"
> >>>>>> +"       sd   ra,32(sp)\n"
> >>>>>> +"       call my_direct_func\n"
> >>>>>> +"       ld   a0,0(sp)\n"
> >>>>>> +"       ld   a1,8(sp)\n"
> >>>>>> +"       ld   a2,16(sp)\n"
> >>>>>> +"       ld   t0,24(sp)\n"
> >>>>>> +"       ld   ra,32(sp)\n"
> >>>>>> +"       addi sp,sp,40\n"
> >>>>>> +"       jr t0\n"
> >>>>>> +"       .size           my_tramp, .-my_tramp\n"
> >>>>>> +"       .popsection\n"
> >>>>>> +);
> >>>>>> +
> >>>>>> +#endif /* CONFIG_RISCV */
> >>>>>> +
> >>>>>>     #ifdef CONFIG_X86_64
> >>>>>>
> >>>>>>     #include <asm/ibt.h>
> >>>>>> diff --git a/samples/ftrace/ftrace-direct.c
> >>>>>> b/samples/ftrace/ftrace-direct.c
> >>>>>> index 1f769d0db20f..2cfe5a7d2d70 100644
> >>>>>> --- a/samples/ftrace/ftrace-direct.c
> >>>>>> +++ b/samples/ftrace/ftrace-direct.c
> >>>>>> @@ -15,6 +15,28 @@ void my_direct_func(struct task_struct *p)
> >>>>>>
> >>>>>>     extern void my_tramp(void *);
> >>>>>>
> >>>>>> +#ifdef CONFIG_RISCV
> >>>>>> +
> >>>>>> +asm ("       .pushsection    .text, \"ax\", @progbits\n"
> >>>>>> +"       .type           my_tramp, @function\n"
> >>>>>> +"       .globl          my_tramp\n"
> >>>>>> +"   my_tramp:\n"
> >>>>>> +"       addi sp,sp,-24\n"
> >>>>>> +"       sd   a0,0(sp)\n"
> >>>>>> +"       sd   t0,8(sp)\n"
> >>>>>> +"       sd   ra,16(sp)\n"
> >>>>>> +"       call my_direct_func\n"
> >>>>>> +"       ld   a0,0(sp)\n"
> >>>>>> +"       ld   t0,8(sp)\n"
> >>>>>> +"       ld   ra,16(sp)\n"
> >>>>>> +"       addi sp,sp,24\n"
> >>>>>> +"       jr t0\n"
> >>>>>> +"       .size           my_tramp, .-my_tramp\n"
> >>>>>> +"       .popsection\n"
> >>>>>> +);
> >>>>>> +
> >>>>>> +#endif /* CONFIG_RISCV */
> >>>>>> +
> >>>>>>     #ifdef CONFIG_X86_64
> >>>>>>
> >>>>>>     #include <asm/ibt.h>
> >>>>>> --
> >>>>>> 2.36.1
> >>>>
> >>>> --
> >>>> Thanks,
> >>>> Song
> >>>>
> >>>
> >>> Regards,
> >>> Evgenii
> >>
> >>
> >
> >
> > --
> > Thanks,
> > Song
> >
>
>
  

On Wed, 18 Jan 2023 22:05:04 PST (-0800), guoren@kernel.org wrote:
> Thx Evgenii & Song,
>
> I got it; it would be put into v8.

Sorry if I missed it, but I don't see a v8 on patchwork.  I queued up 
the first three patches onto for-next as they seem like pretty 
independent fixes/cleanups, I'll hold off on the others until v8.

Thanks!

>
> On Wed, Jan 18, 2023 at 11:19 PM Evgenii Shatokhin
> <e.shatokhin@yadro.com> wrote:
>>
>> On 18.01.2023 05:37, Song Shuai wrote:
>> > Evgenii Shatokhin <e.shatokhin@yadro.com> 于2023年1月17日周二 16:22写道：
>> >>
>> >> On 17.01.2023 16:16, Evgenii Shatokhin wrote:
>> >>> Hi, Song,
>> >>>
>> >>> On 17.01.2023 12:32, Song Shuai wrote:
>> >>>>
>> >>>> Hi, Evgenii:
>> >>>>
>> >>>> Evgenii Shatokhin <e.shatokhin@yadro.com> 于2023年1月16日周一 14:30写道：
>> >>>>
>> >>>>>
>> >>>>> Hi,
>> >>>>>
>> >>>>> On 12.01.2023 12:06, guoren@kernel.org wrote:
>> >>>>>> From: Song Shuai <suagrfillet@gmail.com>
>> >>>>>>
>> >>>>>> select HAVE_SAMPLE_FTRACE_DIRECT and HAVE_SAMPLE_FTRACE_DIRECT_MULTI
>> >>>>>> for ARCH_RV64I in arch/riscv/Kconfig. And add riscv asm code for
>> >>>>>> the ftrace-direct*.c files in samples/ftrace/.
>> >>>>>>
>> >>>>>> Signed-off-by: Song Shuai <suagrfillet@gmail.com>
>> >>>>>> Tested-by: Guo Ren <guoren@kernel.org>
>> >>>>>> Signed-off-by: Guo Ren <guoren@kernel.org>
>> >>>>>> ---
>> >>>>>>     arch/riscv/Kconfig                          |  2 ++
>> >>>>>>     samples/ftrace/ftrace-direct-modify.c       | 33 ++++++++++++++++++
>> >>>>>>     samples/ftrace/ftrace-direct-multi-modify.c | 37
>> >>>>>> +++++++++++++++++++++
>> >>>>>>     samples/ftrace/ftrace-direct-multi.c        | 22 ++++++++++++
>> >>>>>>     samples/ftrace/ftrace-direct-too.c          | 26 +++++++++++++++
>> >>>>>>     samples/ftrace/ftrace-direct.c              | 22 ++++++++++++
>> >>>>>>     6 files changed, 142 insertions(+)
>> >>>>>
>> >>>>> The samples were built OK now, but ftrace-direct-multi and
>> >>>>> ftrace-direct-multi-modify report incorrect values of ip/pc it seems.
>> >>>>>
>> >>>>> I ran 'insmod ftrace-direct-multi.ko', waited a little and then checked
>> >>>>> the messages in the trace:
>> >>>>>
>> >>>>> #           TASK-PID     CPU#  |||||  TIMESTAMP  FUNCTION
>> >>>>> #              | |         |   |||||     |         |
>> >>>>>         migration/1-19      [001] .....  3858.532131: my_direct_func1: my
>> >>>>> direct func1 ip 0
>> >>>>>         migration/0-15      [000] d.s2.  3858.532136: my_direct_func1: my
>> >>>>> direct func1 ip ff60000001ba9600
>> >>>>>         migration/0-15      [000] d..2.  3858.532204: my_direct_func1: my
>> >>>>> direct func1 ip ff60000003334d00
>> >>>>>         migration/0-15      [000] .....  3858.532232: my_direct_func1: my
>> >>>>> direct func1 ip 0
>> >>>>>           rcu_sched-14      [001] .....  3858.532257: my_direct_func1: my
>> >>>>> direct func1 ip 0
>> >>>>>              insmod-415     [000] .....  3858.532270: my_direct_func1: my
>> >>>>> direct func1 ip 7fffffffffffffff
>> >>>>>              <idle>-0       [001] ..s1.  3858.539051: my_direct_func1: my
>> >>>>> direct func1 ip ff60000001ba9600
>> >>>>>              <idle>-0       [001] dns2.  3858.539124: my_direct_func1: my
>> >>>>> direct func1 ip ff60000001ba9600
>> >>>>>           rcu_sched-14      [001] .....  3858.539208: my_direct_func1: my
>> >>>>> direct func1 ip 0
>> >>>>> [...]
>> >>>>>
>> >>>>> If I understand it right, my_direct_func1() should print the address of
>> >>>>> some location in the code, probably - at the beginning of the traced
>> >>>>> functions.
>> >>>>>
>> >>>>> The printed values (0x0, 0x7fffffffffffffff, ...) are not valid code
>> >>>>> addresses.
>> >>>>>
>> >>>> The invalid code address is only printed by accessing the schedule()
>> >>>> function's first argument whose address stores in a0 register.
>> >>>> While schedule() actually has no parameter declared, so my_direct_func
>> >>>> just prints the a0 in the context of the schedule()'s caller and
>> >>>> the address maybe varies depending on the caller.
>> >>>>
>> >>>> I can't really understand why tracing the first argument of the
>> >>>> schedule() function, but it seems nonsense at this point.
>> >>>
>> >>> The question is, what should be passed as the argument(s) of
>> >>> my_direct_func() in this particular sample module. The kernel docs and
>> >>> commit logs seem to contain no info on that.
>> >>>
>> >>> With direct functions, I suppose, the trampoline can pass anything it
>> >>> wants to my_direct_func(), not just the arguments of the traced function.
>> >>>
>> >>> I'd check what these sample modules do on x86 and would try to match
>> >>> that behaviour on RISC-V.
>> >>
>> >> I have checked ftrace-direct-multi.ko and ftrace-direct-multi-modify.ko
>> >> on 6.2-rc4 built for x86-64 - yes, ip/pc in the traced function should
>> >> be passed to my_direct_func().
>> >>
>> >> ftrace-direct-multi.ko:
>> >> #           TASK-PID     CPU#  |||||  TIMESTAMP  FUNCTION
>> >> #              | |         |   |||||     |         |
>> >>             insmod-10829   [000] d.h1.  1719.518535: my_direct_func: ip
>> >> ffffffff87332f45 // wake_up_process+0x5
>> >>    rcu_tasks_kthre-11      [000] .....  1719.518696: my_direct_func: ip
>> >> ffffffff8828d935 // schedule+0x5
>> >>             insmod-10829   [000] .....  1719.518708: my_direct_func: ip
>> >> ffffffff8828d935
>> >>    systemd-journal-293     [001] .....  1719.518823: my_direct_func: ip
>> >> ffffffff8828d935
>> >>            systemd-1       [000] .....  1719.519141: my_direct_func: ip
>> >> ffffffff8828d935
>> >>             <idle>-0       [001] ..s1.  1719.521889: my_direct_func: ip
>> >> ffffffff87332f45
>> >>             <idle>-0       [000] d.s2.  1719.521901: my_direct_func: ip
>> >> ffffffff87332f45
>> >>        rcu_preempt-15      [001] .....  1719.521917: my_direct_func: ip
>> >> ffffffff8828d935
>> >> [...]
>> >>
>> >> The ip values are wake_up_process+0x5 and schedule+0x5, the locations
>> >> where the execution of the traced functions resumes after the Ftrace
>> >> trampoline has finished.
>> >>
>> >> The results with ftrace-direct-multi-modify.ko are similar to that.
>> >>
>> >> The samples look like a demonstration, that one can pass anything
>> >> necessary to the handler in case of "direct" functions.
>> >>
>> >> I suppose, the RISC-V-specific asm code in these two sample modules
>> >> could be updated to pass the saved pc value to my_direct_func() in a0.
>> >
>> > Yes, you're right.
>> >
>> > I added 'mv a0,t0' in front of `call my_direct_func` to pass the address of
>> > traced function with mcount offset.
>> >
>> > Here is the updated patch for your reference.
>> > https://github.com/sugarfillet/linux/commit/95b174fb104dd970b982ee6fa19879393e229318
>>
>> Thank you for the quick fix. This one looks good to me.
>>
>> ftrace-direct-multi*.ko now report the ip values corresponding to
>> schedule+0x8 and wake_up_process+0x8, which is what was expected here.
>>
>> One more thing: please change my "Co-developed-by:" into "Tested-by:" in
>> your patch, becase this is what I actually did: tested it and reported
>> the results. I cannot take your credit for development of this patch ;-)
>>
>> Looking forward for v8 of the series.
>> >
>> >
>> >>
>> >>>
>> >>>>
>> >>>> As for this patch, it just impls a simple mcount (direct_caller) to
>> >>>> trace kernel functions, and basically saves the necessary ABI,
>> >>>> call the tracing function, and restores the ABI, just like other
>> >>>> arches do.
>> >>>> so It shouldn't be blamed.
>> >>>>
>> >>>> I started an independent patch to replace schedule with kick_process
>> >>>> to make these samples more reasonable. And It has no conflict with the
>> >>>> current patch, so we can go on.
>> >>>>
>> >>>> Link:
>> >>>> https://lore.kernel.org/linux-kernel/20230117091101.3669996-1-suagrfillet@gmail.com/T/#u
>> >>>>
>> >>>>> The same issue is with ftrace-direct-multi-modify.ko.
>> >>>>>
>> >>>>> Is anything missing here?
>> >>>>>
>> >>>>>>
>> >>>>>> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
>> >>>>>> index 307a9f413edd..e944af44f681 100644
>> >>>>>> --- a/arch/riscv/Kconfig
>> >>>>>> +++ b/arch/riscv/Kconfig
>> >>>>>> @@ -112,6 +112,8 @@ config RISCV
>> >>>>>>            select HAVE_POSIX_CPU_TIMERS_TASK_WORK
>> >>>>>>            select HAVE_REGS_AND_STACK_ACCESS_API
>> >>>>>>            select HAVE_FUNCTION_ARG_ACCESS_API
>> >>>>>> +       select HAVE_SAMPLE_FTRACE_DIRECT
>> >>>>>> +       select HAVE_SAMPLE_FTRACE_DIRECT_MULTI
>> >>>>>>            select HAVE_STACKPROTECTOR
>> >>>>>>            select HAVE_SYSCALL_TRACEPOINTS
>> >>>>>>            select HAVE_RSEQ
>> >>>>>> diff --git a/samples/ftrace/ftrace-direct-modify.c
>> >>>>>> b/samples/ftrace/ftrace-direct-modify.c
>> >>>>>> index de5a0f67f320..be7bf472c3c7 100644
>> >>>>>> --- a/samples/ftrace/ftrace-direct-modify.c
>> >>>>>> +++ b/samples/ftrace/ftrace-direct-modify.c
>> >>>>>> @@ -23,6 +23,39 @@ extern void my_tramp2(void *);
>> >>>>>>
>> >>>>>>     static unsigned long my_ip = (unsigned long)schedule;
>> >>>>>>
>> >>>>>> +#ifdef CONFIG_RISCV
>> >>>>>> +
>> >>>>>> +asm (" .pushsection    .text, \"ax\", @progbits\n"
>> >>>>>> +"      .type           my_tramp1, @function\n"
>> >>>>>> +"      .globl          my_tramp1\n"
>> >>>>>> +"   my_tramp1:\n"
>> >>>>>> +"      addi sp,sp,-16\n"
>> >>>>>> +"      sd   t0,0(sp)\n"
>> >>>>>> +"      sd   ra,8(sp)\n"
>> >>>>>> +"      call my_direct_func1\n"
>> >>>>>> +"      ld   t0,0(sp)\n"
>> >>>>>> +"      ld   ra,8(sp)\n"
>> >>>>>> +"      addi sp,sp,16\n"
>> >>>>>> +"      jr t0\n"
>> >>>>>> +"      .size           my_tramp1, .-my_tramp1\n"
>> >>>>>> +
>> >>>>>> +"      .type           my_tramp2, @function\n"
>> >>>>>> +"      .globl          my_tramp2\n"
>> >>>>>> +"   my_tramp2:\n"
>> >>>>>> +"      addi sp,sp,-16\n"
>> >>>>>> +"      sd   t0,0(sp)\n"
>> >>>>>> +"      sd   ra,8(sp)\n"
>> >>>>>> +"      call my_direct_func2\n"
>> >>>>>> +"      ld   t0,0(sp)\n"
>> >>>>>> +"      ld   ra,8(sp)\n"
>> >>>>>> +"      addi sp,sp,16\n"
>> >>>>>> +"      jr t0\n"
>> >>>>>> +"      .size           my_tramp2, .-my_tramp2\n"
>> >>>>>> +"      .popsection\n"
>> >>>>>> +);
>> >>>>>> +
>> >>>>>> +#endif /* CONFIG_RISCV */
>> >>>>>> +
>> >>>>>>     #ifdef CONFIG_X86_64
>> >>>>>>
>> >>>>>>     #include <asm/ibt.h>
>> >>>>>> diff --git a/samples/ftrace/ftrace-direct-multi-modify.c
>> >>>>>> b/samples/ftrace/ftrace-direct-multi-modify.c
>> >>>>>> index d52370cad0b6..10884bf418f7 100644
>> >>>>>> --- a/samples/ftrace/ftrace-direct-multi-modify.c
>> >>>>>> +++ b/samples/ftrace/ftrace-direct-multi-modify.c
>> >>>>>> @@ -21,6 +21,43 @@ void my_direct_func2(unsigned long ip)
>> >>>>>>     extern void my_tramp1(void *);
>> >>>>>>     extern void my_tramp2(void *);
>> >>>>>>
>> >>>>>> +#ifdef CONFIG_RISCV
>> >>>>>> +
>> >>>>>> +asm (" .pushsection    .text, \"ax\", @progbits\n"
>> >>>>>> +"      .type           my_tramp1, @function\n"
>> >>>>>> +"      .globl          my_tramp1\n"
>> >>>>>> +"   my_tramp1:\n"
>> >>>>>> +"       addi sp,sp,-24\n"
>> >>>>>> +"       sd   a0,0(sp)\n"
>> >>>>>> +"       sd   t0,8(sp)\n"
>> >>>>>> +"       sd   ra,16(sp)\n"
>> >>>>>> +"       call my_direct_func1\n"
>> >>>>>> +"       ld   a0,0(sp)\n"
>> >>>>>> +"       ld   t0,8(sp)\n"
>> >>>>>> +"       ld   ra,16(sp)\n"
>> >>>>>> +"       addi sp,sp,24\n"
>> >>>>>> +"      jr t0\n"
>> >>>>>> +"      .size           my_tramp1, .-my_tramp1\n"
>> >>>>>> +
>> >>>>>> +"      .type           my_tramp2, @function\n"
>> >>>>>> +"      .globl          my_tramp2\n"
>> >>>>>> +"   my_tramp2:\n"
>> >>>>>> +"       addi sp,sp,-24\n"
>> >>>>>> +"       sd   a0,0(sp)\n"
>> >>>>>> +"       sd   t0,8(sp)\n"
>> >>>>>> +"       sd   ra,16(sp)\n"
>> >>>>>> +"       call my_direct_func2\n"
>> >>>>>> +"       ld   a0,0(sp)\n"
>> >>>>>> +"       ld   t0,8(sp)\n"
>> >>>>>> +"       ld   ra,16(sp)\n"
>> >>>>>> +"       addi sp,sp,24\n"
>> >>>>>> +"      jr t0\n"
>> >>>>>> +"      .size           my_tramp2, .-my_tramp2\n"
>> >>>>>> +"      .popsection\n"
>> >>>>>> +);
>> >>>>>> +
>> >>>>>> +#endif /* CONFIG_RISCV */
>> >>>>>> +
>> >>>>>>     #ifdef CONFIG_X86_64
>> >>>>>>
>> >>>>>>     #include <asm/ibt.h>
>> >>>>>> diff --git a/samples/ftrace/ftrace-direct-multi.c
>> >>>>>> b/samples/ftrace/ftrace-direct-multi.c
>> >>>>>> index ec1088922517..a35bf43bf6d7 100644
>> >>>>>> --- a/samples/ftrace/ftrace-direct-multi.c
>> >>>>>> +++ b/samples/ftrace/ftrace-direct-multi.c
>> >>>>>> @@ -16,6 +16,28 @@ void my_direct_func(unsigned long ip)
>> >>>>>>
>> >>>>>>     extern void my_tramp(void *);
>> >>>>>>
>> >>>>>> +#ifdef CONFIG_RISCV
>> >>>>>> +
>> >>>>>> +asm ("       .pushsection    .text, \"ax\", @progbits\n"
>> >>>>>> +"       .type           my_tramp, @function\n"
>> >>>>>> +"       .globl          my_tramp\n"
>> >>>>>> +"   my_tramp:\n"
>> >>>>>> +"       addi sp,sp,-24\n"
>> >>>>>> +"       sd   a0,0(sp)\n"
>> >>>>>> +"       sd   t0,8(sp)\n"
>> >>>>>> +"       sd   ra,16(sp)\n"
>> >>>>>> +"       call my_direct_func\n"
>> >>>>>> +"       ld   a0,0(sp)\n"
>> >>>>>> +"       ld   t0,8(sp)\n"
>> >>>>>> +"       ld   ra,16(sp)\n"
>> >>>>>> +"       addi sp,sp,24\n"
>> >>>>>> +"       jr t0\n"
>> >>>>>> +"       .size           my_tramp, .-my_tramp\n"
>> >>>>>> +"       .popsection\n"
>> >>>>>> +);
>> >>>>>> +
>> >>>>>> +#endif /* CONFIG_RISCV */
>> >>>>>> +
>> >>>>>>     #ifdef CONFIG_X86_64
>> >>>>>>
>> >>>>>>     #include <asm/ibt.h>
>> >>>>>> diff --git a/samples/ftrace/ftrace-direct-too.c
>> >>>>>> b/samples/ftrace/ftrace-direct-too.c
>> >>>>>> index e13fb59a2b47..3b62e33c2e6d 100644
>> >>>>>> --- a/samples/ftrace/ftrace-direct-too.c
>> >>>>>> +++ b/samples/ftrace/ftrace-direct-too.c
>> >>>>>> @@ -18,6 +18,32 @@ void my_direct_func(struct vm_area_struct *vma,
>> >>>>>>
>> >>>>>>     extern void my_tramp(void *);
>> >>>>>>
>> >>>>>> +#ifdef CONFIG_RISCV
>> >>>>>> +
>> >>>>>> +asm ("       .pushsection    .text, \"ax\", @progbits\n"
>> >>>>>> +"       .type           my_tramp, @function\n"
>> >>>>>> +"       .globl          my_tramp\n"
>> >>>>>> +"   my_tramp:\n"
>> >>>>>> +"       addi sp,sp,-40\n"
>> >>>>>> +"       sd   a0,0(sp)\n"
>> >>>>>> +"       sd   a1,8(sp)\n"
>> >>>>>> +"       sd   a2,16(sp)\n"
>> >>>>>> +"       sd   t0,24(sp)\n"
>> >>>>>> +"       sd   ra,32(sp)\n"
>> >>>>>> +"       call my_direct_func\n"
>> >>>>>> +"       ld   a0,0(sp)\n"
>> >>>>>> +"       ld   a1,8(sp)\n"
>> >>>>>> +"       ld   a2,16(sp)\n"
>> >>>>>> +"       ld   t0,24(sp)\n"
>> >>>>>> +"       ld   ra,32(sp)\n"
>> >>>>>> +"       addi sp,sp,40\n"
>> >>>>>> +"       jr t0\n"
>> >>>>>> +"       .size           my_tramp, .-my_tramp\n"
>> >>>>>> +"       .popsection\n"
>> >>>>>> +);
>> >>>>>> +
>> >>>>>> +#endif /* CONFIG_RISCV */
>> >>>>>> +
>> >>>>>>     #ifdef CONFIG_X86_64
>> >>>>>>
>> >>>>>>     #include <asm/ibt.h>
>> >>>>>> diff --git a/samples/ftrace/ftrace-direct.c
>> >>>>>> b/samples/ftrace/ftrace-direct.c
>> >>>>>> index 1f769d0db20f..2cfe5a7d2d70 100644
>> >>>>>> --- a/samples/ftrace/ftrace-direct.c
>> >>>>>> +++ b/samples/ftrace/ftrace-direct.c
>> >>>>>> @@ -15,6 +15,28 @@ void my_direct_func(struct task_struct *p)
>> >>>>>>
>> >>>>>>     extern void my_tramp(void *);
>> >>>>>>
>> >>>>>> +#ifdef CONFIG_RISCV
>> >>>>>> +
>> >>>>>> +asm ("       .pushsection    .text, \"ax\", @progbits\n"
>> >>>>>> +"       .type           my_tramp, @function\n"
>> >>>>>> +"       .globl          my_tramp\n"
>> >>>>>> +"   my_tramp:\n"
>> >>>>>> +"       addi sp,sp,-24\n"
>> >>>>>> +"       sd   a0,0(sp)\n"
>> >>>>>> +"       sd   t0,8(sp)\n"
>> >>>>>> +"       sd   ra,16(sp)\n"
>> >>>>>> +"       call my_direct_func\n"
>> >>>>>> +"       ld   a0,0(sp)\n"
>> >>>>>> +"       ld   t0,8(sp)\n"
>> >>>>>> +"       ld   ra,16(sp)\n"
>> >>>>>> +"       addi sp,sp,24\n"
>> >>>>>> +"       jr t0\n"
>> >>>>>> +"       .size           my_tramp, .-my_tramp\n"
>> >>>>>> +"       .popsection\n"
>> >>>>>> +);
>> >>>>>> +
>> >>>>>> +#endif /* CONFIG_RISCV */
>> >>>>>> +
>> >>>>>>     #ifdef CONFIG_X86_64
>> >>>>>>
>> >>>>>>     #include <asm/ibt.h>
>> >>>>>> --
>> >>>>>> 2.36.1
>> >>>>
>> >>>> --
>> >>>> Thanks,
>> >>>> Song
>> >>>>
>> >>>
>> >>> Regards,
>> >>> Evgenii
>> >>
>> >>
>> >
>> >
>> > --
>> > Thanks,
>> > Song
>> >
>>
>>
>
>
> -- 
> Best Regards
>  Guo Ren
  

Hi,Guo:

Palmer Dabbelt <palmer@dabbelt.com> 于2023年2月18日周六 21:30写道：
>
> On Wed, 18 Jan 2023 22:05:04 PST (-0800), guoren@kernel.org wrote:
> > Thx Evgenii & Song,
> >
> > I got it; it would be put into v8.
>
There were 2 problems for this patch in its V6 and V7 version:

1. build error resulted by including of nospec-branch.h file in V6
    - this common fixup patch had been sent to the linux-trace mail
list and would show up in Linux v6.3
    - here is the link:
https://lore.kernel.org/lkml/20230208015633.791198913@goodmis.org/

2. invalid code address reported by Evgenii in V7
    - for your convenience, the link to this updated patch is
      https://github.com/sugarfillet/linux/commit/95b174fb104dd970b982ee6fa19879393e229318

Is it time to launch the V8 with this updated patch, or waiting for
the common fixup patch to be merged?

> Sorry if I missed it, but I don't see a v8 on patchwork.  I queued up
> the first three patches onto for-next as they seem like pretty
> independent fixes/cleanups, I'll hold off on the others until v8.
>
> Thanks!
>
> >
> > On Wed, Jan 18, 2023 at 11:19 PM Evgenii Shatokhin
> > <e.shatokhin@yadro.com> wrote:
> >>
> >> On 18.01.2023 05:37, Song Shuai wrote:
> >> > Evgenii Shatokhin <e.shatokhin@yadro.com> 于2023年1月17日周二 16:22写道：
> >> >>
> >> >> On 17.01.2023 16:16, Evgenii Shatokhin wrote:
> >> >>> Hi, Song,
> >> >>>
> >> >>> On 17.01.2023 12:32, Song Shuai wrote:
> >> >>>>
> >> >>>> Hi, Evgenii:
> >> >>>>
> >> >>>> Evgenii Shatokhin <e.shatokhin@yadro.com> 于2023年1月16日周一 14:30写道：
> >> >>>>
> >> >>>>>
> >> >>>>> Hi,
> >> >>>>>
> >> >>>>> On 12.01.2023 12:06, guoren@kernel.org wrote:
> >> >>>>>> From: Song Shuai <suagrfillet@gmail.com>
> >> >>>>>>
> >> >>>>>> select HAVE_SAMPLE_FTRACE_DIRECT and HAVE_SAMPLE_FTRACE_DIRECT_MULTI
> >> >>>>>> for ARCH_RV64I in arch/riscv/Kconfig. And add riscv asm code for
> >> >>>>>> the ftrace-direct*.c files in samples/ftrace/.
> >> >>>>>>
> >> >>>>>> Signed-off-by: Song Shuai <suagrfillet@gmail.com>
> >> >>>>>> Tested-by: Guo Ren <guoren@kernel.org>
> >> >>>>>> Signed-off-by: Guo Ren <guoren@kernel.org>
> >> >>>>>> ---
> >> >>>>>>     arch/riscv/Kconfig                          |  2 ++
> >> >>>>>>     samples/ftrace/ftrace-direct-modify.c       | 33 ++++++++++++++++++
> >> >>>>>>     samples/ftrace/ftrace-direct-multi-modify.c | 37
> >> >>>>>> +++++++++++++++++++++
> >> >>>>>>     samples/ftrace/ftrace-direct-multi.c        | 22 ++++++++++++
> >> >>>>>>     samples/ftrace/ftrace-direct-too.c          | 26 +++++++++++++++
> >> >>>>>>     samples/ftrace/ftrace-direct.c              | 22 ++++++++++++
> >> >>>>>>     6 files changed, 142 insertions(+)
> >> >>>>>
> >> >>>>> The samples were built OK now, but ftrace-direct-multi and
> >> >>>>> ftrace-direct-multi-modify report incorrect values of ip/pc it seems.
> >> >>>>>
> >> >>>>> I ran 'insmod ftrace-direct-multi.ko', waited a little and then checked
> >> >>>>> the messages in the trace:
> >> >>>>>
> >> >>>>> #           TASK-PID     CPU#  |||||  TIMESTAMP  FUNCTION
> >> >>>>> #              | |         |   |||||     |         |
> >> >>>>>         migration/1-19      [001] .....  3858.532131: my_direct_func1: my
> >> >>>>> direct func1 ip 0
> >> >>>>>         migration/0-15      [000] d.s2.  3858.532136: my_direct_func1: my
> >> >>>>> direct func1 ip ff60000001ba9600
> >> >>>>>         migration/0-15      [000] d..2.  3858.532204: my_direct_func1: my
> >> >>>>> direct func1 ip ff60000003334d00
> >> >>>>>         migration/0-15      [000] .....  3858.532232: my_direct_func1: my
> >> >>>>> direct func1 ip 0
> >> >>>>>           rcu_sched-14      [001] .....  3858.532257: my_direct_func1: my
> >> >>>>> direct func1 ip 0
> >> >>>>>              insmod-415     [000] .....  3858.532270: my_direct_func1: my
> >> >>>>> direct func1 ip 7fffffffffffffff
> >> >>>>>              <idle>-0       [001] ..s1.  3858.539051: my_direct_func1: my
> >> >>>>> direct func1 ip ff60000001ba9600
> >> >>>>>              <idle>-0       [001] dns2.  3858.539124: my_direct_func1: my
> >> >>>>> direct func1 ip ff60000001ba9600
> >> >>>>>           rcu_sched-14      [001] .....  3858.539208: my_direct_func1: my
> >> >>>>> direct func1 ip 0
> >> >>>>> [...]
> >> >>>>>
> >> >>>>> If I understand it right, my_direct_func1() should print the address of
> >> >>>>> some location in the code, probably - at the beginning of the traced
> >> >>>>> functions.
> >> >>>>>
> >> >>>>> The printed values (0x0, 0x7fffffffffffffff, ...) are not valid code
> >> >>>>> addresses.
> >> >>>>>
> >> >>>> The invalid code address is only printed by accessing the schedule()
> >> >>>> function's first argument whose address stores in a0 register.
> >> >>>> While schedule() actually has no parameter declared, so my_direct_func
> >> >>>> just prints the a0 in the context of the schedule()'s caller and
> >> >>>> the address maybe varies depending on the caller.
> >> >>>>
> >> >>>> I can't really understand why tracing the first argument of the
> >> >>>> schedule() function, but it seems nonsense at this point.
> >> >>>
> >> >>> The question is, what should be passed as the argument(s) of
> >> >>> my_direct_func() in this particular sample module. The kernel docs and
> >> >>> commit logs seem to contain no info on that.
> >> >>>
> >> >>> With direct functions, I suppose, the trampoline can pass anything it
> >> >>> wants to my_direct_func(), not just the arguments of the traced function.
> >> >>>
> >> >>> I'd check what these sample modules do on x86 and would try to match
> >> >>> that behaviour on RISC-V.
> >> >>
> >> >> I have checked ftrace-direct-multi.ko and ftrace-direct-multi-modify.ko
> >> >> on 6.2-rc4 built for x86-64 - yes, ip/pc in the traced function should
> >> >> be passed to my_direct_func().
> >> >>
> >> >> ftrace-direct-multi.ko:
> >> >> #           TASK-PID     CPU#  |||||  TIMESTAMP  FUNCTION
> >> >> #              | |         |   |||||     |         |
> >> >>             insmod-10829   [000] d.h1.  1719.518535: my_direct_func: ip
> >> >> ffffffff87332f45 // wake_up_process+0x5
> >> >>    rcu_tasks_kthre-11      [000] .....  1719.518696: my_direct_func: ip
> >> >> ffffffff8828d935 // schedule+0x5
> >> >>             insmod-10829   [000] .....  1719.518708: my_direct_func: ip
> >> >> ffffffff8828d935
> >> >>    systemd-journal-293     [001] .....  1719.518823: my_direct_func: ip
> >> >> ffffffff8828d935
> >> >>            systemd-1       [000] .....  1719.519141: my_direct_func: ip
> >> >> ffffffff8828d935
> >> >>             <idle>-0       [001] ..s1.  1719.521889: my_direct_func: ip
> >> >> ffffffff87332f45
> >> >>             <idle>-0       [000] d.s2.  1719.521901: my_direct_func: ip
> >> >> ffffffff87332f45
> >> >>        rcu_preempt-15      [001] .....  1719.521917: my_direct_func: ip
> >> >> ffffffff8828d935
> >> >> [...]
> >> >>
> >> >> The ip values are wake_up_process+0x5 and schedule+0x5, the locations
> >> >> where the execution of the traced functions resumes after the Ftrace
> >> >> trampoline has finished.
> >> >>
> >> >> The results with ftrace-direct-multi-modify.ko are similar to that.
> >> >>
> >> >> The samples look like a demonstration, that one can pass anything
> >> >> necessary to the handler in case of "direct" functions.
> >> >>
> >> >> I suppose, the RISC-V-specific asm code in these two sample modules
> >> >> could be updated to pass the saved pc value to my_direct_func() in a0.
> >> >
> >> > Yes, you're right.
> >> >
> >> > I added 'mv a0,t0' in front of `call my_direct_func` to pass the address of
> >> > traced function with mcount offset.
> >> >
> >> > Here is the updated patch for your reference.
> >> > https://github.com/sugarfillet/linux/commit/95b174fb104dd970b982ee6fa19879393e229318
> >>
> >> Thank you for the quick fix. This one looks good to me.
> >>
> >> ftrace-direct-multi*.ko now report the ip values corresponding to
> >> schedule+0x8 and wake_up_process+0x8, which is what was expected here.
> >>
> >> One more thing: please change my "Co-developed-by:" into "Tested-by:" in
> >> your patch, becase this is what I actually did: tested it and reported
> >> the results. I cannot take your credit for development of this patch ;-)
> >>
> >> Looking forward for v8 of the series.
> >> >
> >> >
> >> >>
> >> >>>
> >> >>>>
> >> >>>> As for this patch, it just impls a simple mcount (direct_caller) to
> >> >>>> trace kernel functions, and basically saves the necessary ABI,
> >> >>>> call the tracing function, and restores the ABI, just like other
> >> >>>> arches do.
> >> >>>> so It shouldn't be blamed.
> >> >>>>
> >> >>>> I started an independent patch to replace schedule with kick_process
> >> >>>> to make these samples more reasonable. And It has no conflict with the
> >> >>>> current patch, so we can go on.
> >> >>>>
> >> >>>> Link:
> >> >>>> https://lore.kernel.org/linux-kernel/20230117091101.3669996-1-suagrfillet@gmail.com/T/#u
> >> >>>>
> >> >>>>> The same issue is with ftrace-direct-multi-modify.ko.
> >> >>>>>
> >> >>>>> Is anything missing here?
> >> >>>>>
> >> >>>>>>
> >> >>>>>> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> >> >>>>>> index 307a9f413edd..e944af44f681 100644
> >> >>>>>> --- a/arch/riscv/Kconfig
> >> >>>>>> +++ b/arch/riscv/Kconfig
> >> >>>>>> @@ -112,6 +112,8 @@ config RISCV
> >> >>>>>>            select HAVE_POSIX_CPU_TIMERS_TASK_WORK
> >> >>>>>>            select HAVE_REGS_AND_STACK_ACCESS_API
> >> >>>>>>            select HAVE_FUNCTION_ARG_ACCESS_API
> >> >>>>>> +       select HAVE_SAMPLE_FTRACE_DIRECT
> >> >>>>>> +       select HAVE_SAMPLE_FTRACE_DIRECT_MULTI
> >> >>>>>>            select HAVE_STACKPROTECTOR
> >> >>>>>>            select HAVE_SYSCALL_TRACEPOINTS
> >> >>>>>>            select HAVE_RSEQ
> >> >>>>>> diff --git a/samples/ftrace/ftrace-direct-modify.c
> >> >>>>>> b/samples/ftrace/ftrace-direct-modify.c
> >> >>>>>> index de5a0f67f320..be7bf472c3c7 100644
> >> >>>>>> --- a/samples/ftrace/ftrace-direct-modify.c
> >> >>>>>> +++ b/samples/ftrace/ftrace-direct-modify.c
> >> >>>>>> @@ -23,6 +23,39 @@ extern void my_tramp2(void *);
> >> >>>>>>
> >> >>>>>>     static unsigned long my_ip = (unsigned long)schedule;
> >> >>>>>>
> >> >>>>>> +#ifdef CONFIG_RISCV
> >> >>>>>> +
> >> >>>>>> +asm (" .pushsection    .text, \"ax\", @progbits\n"
> >> >>>>>> +"      .type           my_tramp1, @function\n"
> >> >>>>>> +"      .globl          my_tramp1\n"
> >> >>>>>> +"   my_tramp1:\n"
> >> >>>>>> +"      addi sp,sp,-16\n"
> >> >>>>>> +"      sd   t0,0(sp)\n"
> >> >>>>>> +"      sd   ra,8(sp)\n"
> >> >>>>>> +"      call my_direct_func1\n"
> >> >>>>>> +"      ld   t0,0(sp)\n"
> >> >>>>>> +"      ld   ra,8(sp)\n"
> >> >>>>>> +"      addi sp,sp,16\n"
> >> >>>>>> +"      jr t0\n"
> >> >>>>>> +"      .size           my_tramp1, .-my_tramp1\n"
> >> >>>>>> +
> >> >>>>>> +"      .type           my_tramp2, @function\n"
> >> >>>>>> +"      .globl          my_tramp2\n"
> >> >>>>>> +"   my_tramp2:\n"
> >> >>>>>> +"      addi sp,sp,-16\n"
> >> >>>>>> +"      sd   t0,0(sp)\n"
> >> >>>>>> +"      sd   ra,8(sp)\n"
> >> >>>>>> +"      call my_direct_func2\n"
> >> >>>>>> +"      ld   t0,0(sp)\n"
> >> >>>>>> +"      ld   ra,8(sp)\n"
> >> >>>>>> +"      addi sp,sp,16\n"
> >> >>>>>> +"      jr t0\n"
> >> >>>>>> +"      .size           my_tramp2, .-my_tramp2\n"
> >> >>>>>> +"      .popsection\n"
> >> >>>>>> +);
> >> >>>>>> +
> >> >>>>>> +#endif /* CONFIG_RISCV */
> >> >>>>>> +
> >> >>>>>>     #ifdef CONFIG_X86_64
> >> >>>>>>
> >> >>>>>>     #include <asm/ibt.h>
> >> >>>>>> diff --git a/samples/ftrace/ftrace-direct-multi-modify.c
> >> >>>>>> b/samples/ftrace/ftrace-direct-multi-modify.c
> >> >>>>>> index d52370cad0b6..10884bf418f7 100644
> >> >>>>>> --- a/samples/ftrace/ftrace-direct-multi-modify.c
> >> >>>>>> +++ b/samples/ftrace/ftrace-direct-multi-modify.c
> >> >>>>>> @@ -21,6 +21,43 @@ void my_direct_func2(unsigned long ip)
> >> >>>>>>     extern void my_tramp1(void *);
> >> >>>>>>     extern void my_tramp2(void *);
> >> >>>>>>
> >> >>>>>> +#ifdef CONFIG_RISCV
> >> >>>>>> +
> >> >>>>>> +asm (" .pushsection    .text, \"ax\", @progbits\n"
> >> >>>>>> +"      .type           my_tramp1, @function\n"
> >> >>>>>> +"      .globl          my_tramp1\n"
> >> >>>>>> +"   my_tramp1:\n"
> >> >>>>>> +"       addi sp,sp,-24\n"
> >> >>>>>> +"       sd   a0,0(sp)\n"
> >> >>>>>> +"       sd   t0,8(sp)\n"
> >> >>>>>> +"       sd   ra,16(sp)\n"
> >> >>>>>> +"       call my_direct_func1\n"
> >> >>>>>> +"       ld   a0,0(sp)\n"
> >> >>>>>> +"       ld   t0,8(sp)\n"
> >> >>>>>> +"       ld   ra,16(sp)\n"
> >> >>>>>> +"       addi sp,sp,24\n"
> >> >>>>>> +"      jr t0\n"
> >> >>>>>> +"      .size           my_tramp1, .-my_tramp1\n"
> >> >>>>>> +
> >> >>>>>> +"      .type           my_tramp2, @function\n"
> >> >>>>>> +"      .globl          my_tramp2\n"
> >> >>>>>> +"   my_tramp2:\n"
> >> >>>>>> +"       addi sp,sp,-24\n"
> >> >>>>>> +"       sd   a0,0(sp)\n"
> >> >>>>>> +"       sd   t0,8(sp)\n"
> >> >>>>>> +"       sd   ra,16(sp)\n"
> >> >>>>>> +"       call my_direct_func2\n"
> >> >>>>>> +"       ld   a0,0(sp)\n"
> >> >>>>>> +"       ld   t0,8(sp)\n"
> >> >>>>>> +"       ld   ra,16(sp)\n"
> >> >>>>>> +"       addi sp,sp,24\n"
> >> >>>>>> +"      jr t0\n"
> >> >>>>>> +"      .size           my_tramp2, .-my_tramp2\n"
> >> >>>>>> +"      .popsection\n"
> >> >>>>>> +);
> >> >>>>>> +
> >> >>>>>> +#endif /* CONFIG_RISCV */
> >> >>>>>> +
> >> >>>>>>     #ifdef CONFIG_X86_64
> >> >>>>>>
> >> >>>>>>     #include <asm/ibt.h>
> >> >>>>>> diff --git a/samples/ftrace/ftrace-direct-multi.c
> >> >>>>>> b/samples/ftrace/ftrace-direct-multi.c
> >> >>>>>> index ec1088922517..a35bf43bf6d7 100644
> >> >>>>>> --- a/samples/ftrace/ftrace-direct-multi.c
> >> >>>>>> +++ b/samples/ftrace/ftrace-direct-multi.c
> >> >>>>>> @@ -16,6 +16,28 @@ void my_direct_func(unsigned long ip)
> >> >>>>>>
> >> >>>>>>     extern void my_tramp(void *);
> >> >>>>>>
> >> >>>>>> +#ifdef CONFIG_RISCV
> >> >>>>>> +
> >> >>>>>> +asm ("       .pushsection    .text, \"ax\", @progbits\n"
> >> >>>>>> +"       .type           my_tramp, @function\n"
> >> >>>>>> +"       .globl          my_tramp\n"
> >> >>>>>> +"   my_tramp:\n"
> >> >>>>>> +"       addi sp,sp,-24\n"
> >> >>>>>> +"       sd   a0,0(sp)\n"
> >> >>>>>> +"       sd   t0,8(sp)\n"
> >> >>>>>> +"       sd   ra,16(sp)\n"
> >> >>>>>> +"       call my_direct_func\n"
> >> >>>>>> +"       ld   a0,0(sp)\n"
> >> >>>>>> +"       ld   t0,8(sp)\n"
> >> >>>>>> +"       ld   ra,16(sp)\n"
> >> >>>>>> +"       addi sp,sp,24\n"
> >> >>>>>> +"       jr t0\n"
> >> >>>>>> +"       .size           my_tramp, .-my_tramp\n"
> >> >>>>>> +"       .popsection\n"
> >> >>>>>> +);
> >> >>>>>> +
> >> >>>>>> +#endif /* CONFIG_RISCV */
> >> >>>>>> +
> >> >>>>>>     #ifdef CONFIG_X86_64
> >> >>>>>>
> >> >>>>>>     #include <asm/ibt.h>
> >> >>>>>> diff --git a/samples/ftrace/ftrace-direct-too.c
> >> >>>>>> b/samples/ftrace/ftrace-direct-too.c
> >> >>>>>> index e13fb59a2b47..3b62e33c2e6d 100644
> >> >>>>>> --- a/samples/ftrace/ftrace-direct-too.c
> >> >>>>>> +++ b/samples/ftrace/ftrace-direct-too.c
> >> >>>>>> @@ -18,6 +18,32 @@ void my_direct_func(struct vm_area_struct *vma,
> >> >>>>>>
> >> >>>>>>     extern void my_tramp(void *);
> >> >>>>>>
> >> >>>>>> +#ifdef CONFIG_RISCV
> >> >>>>>> +
> >> >>>>>> +asm ("       .pushsection    .text, \"ax\", @progbits\n"
> >> >>>>>> +"       .type           my_tramp, @function\n"
> >> >>>>>> +"       .globl          my_tramp\n"
> >> >>>>>> +"   my_tramp:\n"
> >> >>>>>> +"       addi sp,sp,-40\n"
> >> >>>>>> +"       sd   a0,0(sp)\n"
> >> >>>>>> +"       sd   a1,8(sp)\n"
> >> >>>>>> +"       sd   a2,16(sp)\n"
> >> >>>>>> +"       sd   t0,24(sp)\n"
> >> >>>>>> +"       sd   ra,32(sp)\n"
> >> >>>>>> +"       call my_direct_func\n"
> >> >>>>>> +"       ld   a0,0(sp)\n"
> >> >>>>>> +"       ld   a1,8(sp)\n"
> >> >>>>>> +"       ld   a2,16(sp)\n"
> >> >>>>>> +"       ld   t0,24(sp)\n"
> >> >>>>>> +"       ld   ra,32(sp)\n"
> >> >>>>>> +"       addi sp,sp,40\n"
> >> >>>>>> +"       jr t0\n"
> >> >>>>>> +"       .size           my_tramp, .-my_tramp\n"
> >> >>>>>> +"       .popsection\n"
> >> >>>>>> +);
> >> >>>>>> +
> >> >>>>>> +#endif /* CONFIG_RISCV */
> >> >>>>>> +
> >> >>>>>>     #ifdef CONFIG_X86_64
> >> >>>>>>
> >> >>>>>>     #include <asm/ibt.h>
> >> >>>>>> diff --git a/samples/ftrace/ftrace-direct.c
> >> >>>>>> b/samples/ftrace/ftrace-direct.c
> >> >>>>>> index 1f769d0db20f..2cfe5a7d2d70 100644
> >> >>>>>> --- a/samples/ftrace/ftrace-direct.c
> >> >>>>>> +++ b/samples/ftrace/ftrace-direct.c
> >> >>>>>> @@ -15,6 +15,28 @@ void my_direct_func(struct task_struct *p)
> >> >>>>>>
> >> >>>>>>     extern void my_tramp(void *);
> >> >>>>>>
> >> >>>>>> +#ifdef CONFIG_RISCV
> >> >>>>>> +
> >> >>>>>> +asm ("       .pushsection    .text, \"ax\", @progbits\n"
> >> >>>>>> +"       .type           my_tramp, @function\n"
> >> >>>>>> +"       .globl          my_tramp\n"
> >> >>>>>> +"   my_tramp:\n"
> >> >>>>>> +"       addi sp,sp,-24\n"
> >> >>>>>> +"       sd   a0,0(sp)\n"
> >> >>>>>> +"       sd   t0,8(sp)\n"
> >> >>>>>> +"       sd   ra,16(sp)\n"
> >> >>>>>> +"       call my_direct_func\n"
> >> >>>>>> +"       ld   a0,0(sp)\n"
> >> >>>>>> +"       ld   t0,8(sp)\n"
> >> >>>>>> +"       ld   ra,16(sp)\n"
> >> >>>>>> +"       addi sp,sp,24\n"
> >> >>>>>> +"       jr t0\n"
> >> >>>>>> +"       .size           my_tramp, .-my_tramp\n"
> >> >>>>>> +"       .popsection\n"
> >> >>>>>> +);
> >> >>>>>> +
> >> >>>>>> +#endif /* CONFIG_RISCV */
> >> >>>>>> +
> >> >>>>>>     #ifdef CONFIG_X86_64
> >> >>>>>>
> >> >>>>>>     #include <asm/ibt.h>
> >> >>>>>> --
> >> >>>>>> 2.36.1
> >> >>>>
> >> >>>> --
> >> >>>> Thanks,
> >> >>>> Song
> >> >>>>
> >> >>>
> >> >>> Regards,
> >> >>> Evgenii
> >> >>
> >> >>
> >> >
> >> >
> >> > --
> >> > Thanks,
> >> > Song
> >> >
> >>
> >>
> >
> >
> > --
> > Best Regards
> >  Guo Ren
  

On Mon, Feb 20, 2023 at 10:46 AM Song Shuai <suagrfillet@gmail.com> wrote:
>
> Hi,Guo:
>
> Palmer Dabbelt <palmer@dabbelt.com> 于2023年2月18日周六 21:30写道：
> >
> > On Wed, 18 Jan 2023 22:05:04 PST (-0800), guoren@kernel.org wrote:
> > > Thx Evgenii & Song,
> > >
> > > I got it; it would be put into v8.
> >
> There were 2 problems for this patch in its V6 and V7 version:
>
> 1. build error resulted by including of nospec-branch.h file in V6
>     - this common fixup patch had been sent to the linux-trace mail
> list and would show up in Linux v6.3
>     - here is the link:
> https://lore.kernel.org/lkml/20230208015633.791198913@goodmis.org/
>
> 2. invalid code address reported by Evgenii in V7
>     - for your convenience, the link to this updated patch is
>       https://github.com/sugarfillet/linux/commit/95b174fb104dd970b982ee6fa19879393e229318
>
> Is it time to launch the V8 with this updated patch, or waiting for
> the common fixup patch to be merged?
I don't know.

I've made v8 based on the newest remotes/palmer/for-next with your
newest branch:
https://github.com/guoren83/linux/tree/ftrace_fixup_v8

I fixed some conflicts with the palmer/for-next, You could send them any time.

>
> > Sorry if I missed it, but I don't see a v8 on patchwork.  I queued up
> > the first three patches onto for-next as they seem like pretty
> > independent fixes/cleanups, I'll hold off on the others until v8.
> >
> > Thanks!
> >
> > >
> > > On Wed, Jan 18, 2023 at 11:19 PM Evgenii Shatokhin
> > > <e.shatokhin@yadro.com> wrote:
> > >>
> > >> On 18.01.2023 05:37, Song Shuai wrote:
> > >> > Evgenii Shatokhin <e.shatokhin@yadro.com> 于2023年1月17日周二 16:22写道：
> > >> >>
> > >> >> On 17.01.2023 16:16, Evgenii Shatokhin wrote:
> > >> >>> Hi, Song,
> > >> >>>
> > >> >>> On 17.01.2023 12:32, Song Shuai wrote:
> > >> >>>>
> > >> >>>> Hi, Evgenii:
> > >> >>>>
> > >> >>>> Evgenii Shatokhin <e.shatokhin@yadro.com> 于2023年1月16日周一 14:30写道：
> > >> >>>>
> > >> >>>>>
> > >> >>>>> Hi,
> > >> >>>>>
> > >> >>>>> On 12.01.2023 12:06, guoren@kernel.org wrote:
> > >> >>>>>> From: Song Shuai <suagrfillet@gmail.com>
> > >> >>>>>>
> > >> >>>>>> select HAVE_SAMPLE_FTRACE_DIRECT and HAVE_SAMPLE_FTRACE_DIRECT_MULTI
> > >> >>>>>> for ARCH_RV64I in arch/riscv/Kconfig. And add riscv asm code for
> > >> >>>>>> the ftrace-direct*.c files in samples/ftrace/.
> > >> >>>>>>
> > >> >>>>>> Signed-off-by: Song Shuai <suagrfillet@gmail.com>
> > >> >>>>>> Tested-by: Guo Ren <guoren@kernel.org>
> > >> >>>>>> Signed-off-by: Guo Ren <guoren@kernel.org>
> > >> >>>>>> ---
> > >> >>>>>>     arch/riscv/Kconfig                          |  2 ++
> > >> >>>>>>     samples/ftrace/ftrace-direct-modify.c       | 33 ++++++++++++++++++
> > >> >>>>>>     samples/ftrace/ftrace-direct-multi-modify.c | 37
> > >> >>>>>> +++++++++++++++++++++
> > >> >>>>>>     samples/ftrace/ftrace-direct-multi.c        | 22 ++++++++++++
> > >> >>>>>>     samples/ftrace/ftrace-direct-too.c          | 26 +++++++++++++++
> > >> >>>>>>     samples/ftrace/ftrace-direct.c              | 22 ++++++++++++
> > >> >>>>>>     6 files changed, 142 insertions(+)
> > >> >>>>>
> > >> >>>>> The samples were built OK now, but ftrace-direct-multi and
> > >> >>>>> ftrace-direct-multi-modify report incorrect values of ip/pc it seems.
> > >> >>>>>
> > >> >>>>> I ran 'insmod ftrace-direct-multi.ko', waited a little and then checked
> > >> >>>>> the messages in the trace:
> > >> >>>>>
> > >> >>>>> #           TASK-PID     CPU#  |||||  TIMESTAMP  FUNCTION
> > >> >>>>> #              | |         |   |||||     |         |
> > >> >>>>>         migration/1-19      [001] .....  3858.532131: my_direct_func1: my
> > >> >>>>> direct func1 ip 0
> > >> >>>>>         migration/0-15      [000] d.s2.  3858.532136: my_direct_func1: my
> > >> >>>>> direct func1 ip ff60000001ba9600
> > >> >>>>>         migration/0-15      [000] d..2.  3858.532204: my_direct_func1: my
> > >> >>>>> direct func1 ip ff60000003334d00
> > >> >>>>>         migration/0-15      [000] .....  3858.532232: my_direct_func1: my
> > >> >>>>> direct func1 ip 0
> > >> >>>>>           rcu_sched-14      [001] .....  3858.532257: my_direct_func1: my
> > >> >>>>> direct func1 ip 0
> > >> >>>>>              insmod-415     [000] .....  3858.532270: my_direct_func1: my
> > >> >>>>> direct func1 ip 7fffffffffffffff
> > >> >>>>>              <idle>-0       [001] ..s1.  3858.539051: my_direct_func1: my
> > >> >>>>> direct func1 ip ff60000001ba9600
> > >> >>>>>              <idle>-0       [001] dns2.  3858.539124: my_direct_func1: my
> > >> >>>>> direct func1 ip ff60000001ba9600
> > >> >>>>>           rcu_sched-14      [001] .....  3858.539208: my_direct_func1: my
> > >> >>>>> direct func1 ip 0
> > >> >>>>> [...]
> > >> >>>>>
> > >> >>>>> If I understand it right, my_direct_func1() should print the address of
> > >> >>>>> some location in the code, probably - at the beginning of the traced
> > >> >>>>> functions.
> > >> >>>>>
> > >> >>>>> The printed values (0x0, 0x7fffffffffffffff, ...) are not valid code
> > >> >>>>> addresses.
> > >> >>>>>
> > >> >>>> The invalid code address is only printed by accessing the schedule()
> > >> >>>> function's first argument whose address stores in a0 register.
> > >> >>>> While schedule() actually has no parameter declared, so my_direct_func
> > >> >>>> just prints the a0 in the context of the schedule()'s caller and
> > >> >>>> the address maybe varies depending on the caller.
> > >> >>>>
> > >> >>>> I can't really understand why tracing the first argument of the
> > >> >>>> schedule() function, but it seems nonsense at this point.
> > >> >>>
> > >> >>> The question is, what should be passed as the argument(s) of
> > >> >>> my_direct_func() in this particular sample module. The kernel docs and
> > >> >>> commit logs seem to contain no info on that.
> > >> >>>
> > >> >>> With direct functions, I suppose, the trampoline can pass anything it
> > >> >>> wants to my_direct_func(), not just the arguments of the traced function.
> > >> >>>
> > >> >>> I'd check what these sample modules do on x86 and would try to match
> > >> >>> that behaviour on RISC-V.
> > >> >>
> > >> >> I have checked ftrace-direct-multi.ko and ftrace-direct-multi-modify.ko
> > >> >> on 6.2-rc4 built for x86-64 - yes, ip/pc in the traced function should
> > >> >> be passed to my_direct_func().
> > >> >>
> > >> >> ftrace-direct-multi.ko:
> > >> >> #           TASK-PID     CPU#  |||||  TIMESTAMP  FUNCTION
> > >> >> #              | |         |   |||||     |         |
> > >> >>             insmod-10829   [000] d.h1.  1719.518535: my_direct_func: ip
> > >> >> ffffffff87332f45 // wake_up_process+0x5
> > >> >>    rcu_tasks_kthre-11      [000] .....  1719.518696: my_direct_func: ip
> > >> >> ffffffff8828d935 // schedule+0x5
> > >> >>             insmod-10829   [000] .....  1719.518708: my_direct_func: ip
> > >> >> ffffffff8828d935
> > >> >>    systemd-journal-293     [001] .....  1719.518823: my_direct_func: ip
> > >> >> ffffffff8828d935
> > >> >>            systemd-1       [000] .....  1719.519141: my_direct_func: ip
> > >> >> ffffffff8828d935
> > >> >>             <idle>-0       [001] ..s1.  1719.521889: my_direct_func: ip
> > >> >> ffffffff87332f45
> > >> >>             <idle>-0       [000] d.s2.  1719.521901: my_direct_func: ip
> > >> >> ffffffff87332f45
> > >> >>        rcu_preempt-15      [001] .....  1719.521917: my_direct_func: ip
> > >> >> ffffffff8828d935
> > >> >> [...]
> > >> >>
> > >> >> The ip values are wake_up_process+0x5 and schedule+0x5, the locations
> > >> >> where the execution of the traced functions resumes after the Ftrace
> > >> >> trampoline has finished.
> > >> >>
> > >> >> The results with ftrace-direct-multi-modify.ko are similar to that.
> > >> >>
> > >> >> The samples look like a demonstration, that one can pass anything
> > >> >> necessary to the handler in case of "direct" functions.
> > >> >>
> > >> >> I suppose, the RISC-V-specific asm code in these two sample modules
> > >> >> could be updated to pass the saved pc value to my_direct_func() in a0.
> > >> >
> > >> > Yes, you're right.
> > >> >
> > >> > I added 'mv a0,t0' in front of `call my_direct_func` to pass the address of
> > >> > traced function with mcount offset.
> > >> >
> > >> > Here is the updated patch for your reference.
> > >> > https://github.com/sugarfillet/linux/commit/95b174fb104dd970b982ee6fa19879393e229318
> > >>
> > >> Thank you for the quick fix. This one looks good to me.
> > >>
> > >> ftrace-direct-multi*.ko now report the ip values corresponding to
> > >> schedule+0x8 and wake_up_process+0x8, which is what was expected here.
> > >>
> > >> One more thing: please change my "Co-developed-by:" into "Tested-by:" in
> > >> your patch, becase this is what I actually did: tested it and reported
> > >> the results. I cannot take your credit for development of this patch ;-)
> > >>
> > >> Looking forward for v8 of the series.
> > >> >
> > >> >
> > >> >>
> > >> >>>
> > >> >>>>
> > >> >>>> As for this patch, it just impls a simple mcount (direct_caller) to
> > >> >>>> trace kernel functions, and basically saves the necessary ABI,
> > >> >>>> call the tracing function, and restores the ABI, just like other
> > >> >>>> arches do.
> > >> >>>> so It shouldn't be blamed.
> > >> >>>>
> > >> >>>> I started an independent patch to replace schedule with kick_process
> > >> >>>> to make these samples more reasonable. And It has no conflict with the
> > >> >>>> current patch, so we can go on.
> > >> >>>>
> > >> >>>> Link:
> > >> >>>> https://lore.kernel.org/linux-kernel/20230117091101.3669996-1-suagrfillet@gmail.com/T/#u
> > >> >>>>
> > >> >>>>> The same issue is with ftrace-direct-multi-modify.ko.
> > >> >>>>>
> > >> >>>>> Is anything missing here?
> > >> >>>>>
> > >> >>>>>>
> > >> >>>>>> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> > >> >>>>>> index 307a9f413edd..e944af44f681 100644
> > >> >>>>>> --- a/arch/riscv/Kconfig
> > >> >>>>>> +++ b/arch/riscv/Kconfig
> > >> >>>>>> @@ -112,6 +112,8 @@ config RISCV
> > >> >>>>>>            select HAVE_POSIX_CPU_TIMERS_TASK_WORK
> > >> >>>>>>            select HAVE_REGS_AND_STACK_ACCESS_API
> > >> >>>>>>            select HAVE_FUNCTION_ARG_ACCESS_API
> > >> >>>>>> +       select HAVE_SAMPLE_FTRACE_DIRECT
> > >> >>>>>> +       select HAVE_SAMPLE_FTRACE_DIRECT_MULTI
> > >> >>>>>>            select HAVE_STACKPROTECTOR
> > >> >>>>>>            select HAVE_SYSCALL_TRACEPOINTS
> > >> >>>>>>            select HAVE_RSEQ
> > >> >>>>>> diff --git a/samples/ftrace/ftrace-direct-modify.c
> > >> >>>>>> b/samples/ftrace/ftrace-direct-modify.c
> > >> >>>>>> index de5a0f67f320..be7bf472c3c7 100644
> > >> >>>>>> --- a/samples/ftrace/ftrace-direct-modify.c
> > >> >>>>>> +++ b/samples/ftrace/ftrace-direct-modify.c
> > >> >>>>>> @@ -23,6 +23,39 @@ extern void my_tramp2(void *);
> > >> >>>>>>
> > >> >>>>>>     static unsigned long my_ip = (unsigned long)schedule;
> > >> >>>>>>
> > >> >>>>>> +#ifdef CONFIG_RISCV
> > >> >>>>>> +
> > >> >>>>>> +asm (" .pushsection    .text, \"ax\", @progbits\n"
> > >> >>>>>> +"      .type           my_tramp1, @function\n"
> > >> >>>>>> +"      .globl          my_tramp1\n"
> > >> >>>>>> +"   my_tramp1:\n"
> > >> >>>>>> +"      addi sp,sp,-16\n"
> > >> >>>>>> +"      sd   t0,0(sp)\n"
> > >> >>>>>> +"      sd   ra,8(sp)\n"
> > >> >>>>>> +"      call my_direct_func1\n"
> > >> >>>>>> +"      ld   t0,0(sp)\n"
> > >> >>>>>> +"      ld   ra,8(sp)\n"
> > >> >>>>>> +"      addi sp,sp,16\n"
> > >> >>>>>> +"      jr t0\n"
> > >> >>>>>> +"      .size           my_tramp1, .-my_tramp1\n"
> > >> >>>>>> +
> > >> >>>>>> +"      .type           my_tramp2, @function\n"
> > >> >>>>>> +"      .globl          my_tramp2\n"
> > >> >>>>>> +"   my_tramp2:\n"
> > >> >>>>>> +"      addi sp,sp,-16\n"
> > >> >>>>>> +"      sd   t0,0(sp)\n"
> > >> >>>>>> +"      sd   ra,8(sp)\n"
> > >> >>>>>> +"      call my_direct_func2\n"
> > >> >>>>>> +"      ld   t0,0(sp)\n"
> > >> >>>>>> +"      ld   ra,8(sp)\n"
> > >> >>>>>> +"      addi sp,sp,16\n"
> > >> >>>>>> +"      jr t0\n"
> > >> >>>>>> +"      .size           my_tramp2, .-my_tramp2\n"
> > >> >>>>>> +"      .popsection\n"
> > >> >>>>>> +);
> > >> >>>>>> +
> > >> >>>>>> +#endif /* CONFIG_RISCV */
> > >> >>>>>> +
> > >> >>>>>>     #ifdef CONFIG_X86_64
> > >> >>>>>>
> > >> >>>>>>     #include <asm/ibt.h>
> > >> >>>>>> diff --git a/samples/ftrace/ftrace-direct-multi-modify.c
> > >> >>>>>> b/samples/ftrace/ftrace-direct-multi-modify.c
> > >> >>>>>> index d52370cad0b6..10884bf418f7 100644
> > >> >>>>>> --- a/samples/ftrace/ftrace-direct-multi-modify.c
> > >> >>>>>> +++ b/samples/ftrace/ftrace-direct-multi-modify.c
> > >> >>>>>> @@ -21,6 +21,43 @@ void my_direct_func2(unsigned long ip)
> > >> >>>>>>     extern void my_tramp1(void *);
> > >> >>>>>>     extern void my_tramp2(void *);
> > >> >>>>>>
> > >> >>>>>> +#ifdef CONFIG_RISCV
> > >> >>>>>> +
> > >> >>>>>> +asm (" .pushsection    .text, \"ax\", @progbits\n"
> > >> >>>>>> +"      .type           my_tramp1, @function\n"
> > >> >>>>>> +"      .globl          my_tramp1\n"
> > >> >>>>>> +"   my_tramp1:\n"
> > >> >>>>>> +"       addi sp,sp,-24\n"
> > >> >>>>>> +"       sd   a0,0(sp)\n"
> > >> >>>>>> +"       sd   t0,8(sp)\n"
> > >> >>>>>> +"       sd   ra,16(sp)\n"
> > >> >>>>>> +"       call my_direct_func1\n"
> > >> >>>>>> +"       ld   a0,0(sp)\n"
> > >> >>>>>> +"       ld   t0,8(sp)\n"
> > >> >>>>>> +"       ld   ra,16(sp)\n"
> > >> >>>>>> +"       addi sp,sp,24\n"
> > >> >>>>>> +"      jr t0\n"
> > >> >>>>>> +"      .size           my_tramp1, .-my_tramp1\n"
> > >> >>>>>> +
> > >> >>>>>> +"      .type           my_tramp2, @function\n"
> > >> >>>>>> +"      .globl          my_tramp2\n"
> > >> >>>>>> +"   my_tramp2:\n"
> > >> >>>>>> +"       addi sp,sp,-24\n"
> > >> >>>>>> +"       sd   a0,0(sp)\n"
> > >> >>>>>> +"       sd   t0,8(sp)\n"
> > >> >>>>>> +"       sd   ra,16(sp)\n"
> > >> >>>>>> +"       call my_direct_func2\n"
> > >> >>>>>> +"       ld   a0,0(sp)\n"
> > >> >>>>>> +"       ld   t0,8(sp)\n"
> > >> >>>>>> +"       ld   ra,16(sp)\n"
> > >> >>>>>> +"       addi sp,sp,24\n"
> > >> >>>>>> +"      jr t0\n"
> > >> >>>>>> +"      .size           my_tramp2, .-my_tramp2\n"
> > >> >>>>>> +"      .popsection\n"
> > >> >>>>>> +);
> > >> >>>>>> +
> > >> >>>>>> +#endif /* CONFIG_RISCV */
> > >> >>>>>> +
> > >> >>>>>>     #ifdef CONFIG_X86_64
> > >> >>>>>>
> > >> >>>>>>     #include <asm/ibt.h>
> > >> >>>>>> diff --git a/samples/ftrace/ftrace-direct-multi.c
> > >> >>>>>> b/samples/ftrace/ftrace-direct-multi.c
> > >> >>>>>> index ec1088922517..a35bf43bf6d7 100644
> > >> >>>>>> --- a/samples/ftrace/ftrace-direct-multi.c
> > >> >>>>>> +++ b/samples/ftrace/ftrace-direct-multi.c
> > >> >>>>>> @@ -16,6 +16,28 @@ void my_direct_func(unsigned long ip)
> > >> >>>>>>
> > >> >>>>>>     extern void my_tramp(void *);
> > >> >>>>>>
> > >> >>>>>> +#ifdef CONFIG_RISCV
> > >> >>>>>> +
> > >> >>>>>> +asm ("       .pushsection    .text, \"ax\", @progbits\n"
> > >> >>>>>> +"       .type           my_tramp, @function\n"
> > >> >>>>>> +"       .globl          my_tramp\n"
> > >> >>>>>> +"   my_tramp:\n"
> > >> >>>>>> +"       addi sp,sp,-24\n"
> > >> >>>>>> +"       sd   a0,0(sp)\n"
> > >> >>>>>> +"       sd   t0,8(sp)\n"
> > >> >>>>>> +"       sd   ra,16(sp)\n"
> > >> >>>>>> +"       call my_direct_func\n"
> > >> >>>>>> +"       ld   a0,0(sp)\n"
> > >> >>>>>> +"       ld   t0,8(sp)\n"
> > >> >>>>>> +"       ld   ra,16(sp)\n"
> > >> >>>>>> +"       addi sp,sp,24\n"
> > >> >>>>>> +"       jr t0\n"
> > >> >>>>>> +"       .size           my_tramp, .-my_tramp\n"
> > >> >>>>>> +"       .popsection\n"
> > >> >>>>>> +);
> > >> >>>>>> +
> > >> >>>>>> +#endif /* CONFIG_RISCV */
> > >> >>>>>> +
> > >> >>>>>>     #ifdef CONFIG_X86_64
> > >> >>>>>>
> > >> >>>>>>     #include <asm/ibt.h>
> > >> >>>>>> diff --git a/samples/ftrace/ftrace-direct-too.c
> > >> >>>>>> b/samples/ftrace/ftrace-direct-too.c
> > >> >>>>>> index e13fb59a2b47..3b62e33c2e6d 100644
> > >> >>>>>> --- a/samples/ftrace/ftrace-direct-too.c
> > >> >>>>>> +++ b/samples/ftrace/ftrace-direct-too.c
> > >> >>>>>> @@ -18,6 +18,32 @@ void my_direct_func(struct vm_area_struct *vma,
> > >> >>>>>>
> > >> >>>>>>     extern void my_tramp(void *);
> > >> >>>>>>
> > >> >>>>>> +#ifdef CONFIG_RISCV
> > >> >>>>>> +
> > >> >>>>>> +asm ("       .pushsection    .text, \"ax\", @progbits\n"
> > >> >>>>>> +"       .type           my_tramp, @function\n"
> > >> >>>>>> +"       .globl          my_tramp\n"
> > >> >>>>>> +"   my_tramp:\n"
> > >> >>>>>> +"       addi sp,sp,-40\n"
> > >> >>>>>> +"       sd   a0,0(sp)\n"
> > >> >>>>>> +"       sd   a1,8(sp)\n"
> > >> >>>>>> +"       sd   a2,16(sp)\n"
> > >> >>>>>> +"       sd   t0,24(sp)\n"
> > >> >>>>>> +"       sd   ra,32(sp)\n"
> > >> >>>>>> +"       call my_direct_func\n"
> > >> >>>>>> +"       ld   a0,0(sp)\n"
> > >> >>>>>> +"       ld   a1,8(sp)\n"
> > >> >>>>>> +"       ld   a2,16(sp)\n"
> > >> >>>>>> +"       ld   t0,24(sp)\n"
> > >> >>>>>> +"       ld   ra,32(sp)\n"
> > >> >>>>>> +"       addi sp,sp,40\n"
> > >> >>>>>> +"       jr t0\n"
> > >> >>>>>> +"       .size           my_tramp, .-my_tramp\n"
> > >> >>>>>> +"       .popsection\n"
> > >> >>>>>> +);
> > >> >>>>>> +
> > >> >>>>>> +#endif /* CONFIG_RISCV */
> > >> >>>>>> +
> > >> >>>>>>     #ifdef CONFIG_X86_64
> > >> >>>>>>
> > >> >>>>>>     #include <asm/ibt.h>
> > >> >>>>>> diff --git a/samples/ftrace/ftrace-direct.c
> > >> >>>>>> b/samples/ftrace/ftrace-direct.c
> > >> >>>>>> index 1f769d0db20f..2cfe5a7d2d70 100644
> > >> >>>>>> --- a/samples/ftrace/ftrace-direct.c
> > >> >>>>>> +++ b/samples/ftrace/ftrace-direct.c
> > >> >>>>>> @@ -15,6 +15,28 @@ void my_direct_func(struct task_struct *p)
> > >> >>>>>>
> > >> >>>>>>     extern void my_tramp(void *);
> > >> >>>>>>
> > >> >>>>>> +#ifdef CONFIG_RISCV
> > >> >>>>>> +
> > >> >>>>>> +asm ("       .pushsection    .text, \"ax\", @progbits\n"
> > >> >>>>>> +"       .type           my_tramp, @function\n"
> > >> >>>>>> +"       .globl          my_tramp\n"
> > >> >>>>>> +"   my_tramp:\n"
> > >> >>>>>> +"       addi sp,sp,-24\n"
> > >> >>>>>> +"       sd   a0,0(sp)\n"
> > >> >>>>>> +"       sd   t0,8(sp)\n"
> > >> >>>>>> +"       sd   ra,16(sp)\n"
> > >> >>>>>> +"       call my_direct_func\n"
> > >> >>>>>> +"       ld   a0,0(sp)\n"
> > >> >>>>>> +"       ld   t0,8(sp)\n"
> > >> >>>>>> +"       ld   ra,16(sp)\n"
> > >> >>>>>> +"       addi sp,sp,24\n"
> > >> >>>>>> +"       jr t0\n"
> > >> >>>>>> +"       .size           my_tramp, .-my_tramp\n"
> > >> >>>>>> +"       .popsection\n"
> > >> >>>>>> +);
> > >> >>>>>> +
> > >> >>>>>> +#endif /* CONFIG_RISCV */
> > >> >>>>>> +
> > >> >>>>>>     #ifdef CONFIG_X86_64
> > >> >>>>>>
> > >> >>>>>>     #include <asm/ibt.h>
> > >> >>>>>> --
> > >> >>>>>> 2.36.1
> > >> >>>>
> > >> >>>> --
> > >> >>>> Thanks,
> > >> >>>> Song
> > >> >>>>
> > >> >>>
> > >> >>> Regards,
> > >> >>> Evgenii
> > >> >>
> > >> >>
> > >> >
> > >> >
> > >> > --
> > >> > Thanks,
> > >> > Song
> > >> >
> > >>
> > >>
> > >
> > >
> > > --
> > > Best Regards
> > >  Guo Ren
>
>
>
> --
> Thanks,
> Song
  

On Sun, Feb 19, 2023 at 5:30 AM Palmer Dabbelt <palmer@dabbelt.com> wrote:
>
> On Wed, 18 Jan 2023 22:05:04 PST (-0800), guoren@kernel.org wrote:
> > Thx Evgenii & Song,
> >
> > I got it; it would be put into v8.
>
> Sorry if I missed it, but I don't see a v8 on patchwork.  I queued up
> the first three patches onto for-next as they seem like pretty
> independent fixes/cleanups, I'll hold off on the others until v8.
Thx for approving. I would keep the patch series more independent next time.


>
> Thanks!
>
> >
> > On Wed, Jan 18, 2023 at 11:19 PM Evgenii Shatokhin
> > <e.shatokhin@yadro.com> wrote:
> >>
> >> On 18.01.2023 05:37, Song Shuai wrote:
> >> > Evgenii Shatokhin <e.shatokhin@yadro.com> 于2023年1月17日周二 16:22写道：
> >> >>
> >> >> On 17.01.2023 16:16, Evgenii Shatokhin wrote:
> >> >>> Hi, Song,
> >> >>>
> >> >>> On 17.01.2023 12:32, Song Shuai wrote:
> >> >>>>
> >> >>>> Hi, Evgenii:
> >> >>>>
> >> >>>> Evgenii Shatokhin <e.shatokhin@yadro.com> 于2023年1月16日周一 14:30写道：
> >> >>>>
> >> >>>>>
> >> >>>>> Hi,
> >> >>>>>
> >> >>>>> On 12.01.2023 12:06, guoren@kernel.org wrote:
> >> >>>>>> From: Song Shuai <suagrfillet@gmail.com>
> >> >>>>>>
> >> >>>>>> select HAVE_SAMPLE_FTRACE_DIRECT and HAVE_SAMPLE_FTRACE_DIRECT_MULTI
> >> >>>>>> for ARCH_RV64I in arch/riscv/Kconfig. And add riscv asm code for
> >> >>>>>> the ftrace-direct*.c files in samples/ftrace/.
> >> >>>>>>
> >> >>>>>> Signed-off-by: Song Shuai <suagrfillet@gmail.com>
> >> >>>>>> Tested-by: Guo Ren <guoren@kernel.org>
> >> >>>>>> Signed-off-by: Guo Ren <guoren@kernel.org>
> >> >>>>>> ---
> >> >>>>>>     arch/riscv/Kconfig                          |  2 ++
> >> >>>>>>     samples/ftrace/ftrace-direct-modify.c       | 33 ++++++++++++++++++
> >> >>>>>>     samples/ftrace/ftrace-direct-multi-modify.c | 37
> >> >>>>>> +++++++++++++++++++++
> >> >>>>>>     samples/ftrace/ftrace-direct-multi.c        | 22 ++++++++++++
> >> >>>>>>     samples/ftrace/ftrace-direct-too.c          | 26 +++++++++++++++
> >> >>>>>>     samples/ftrace/ftrace-direct.c              | 22 ++++++++++++
> >> >>>>>>     6 files changed, 142 insertions(+)
> >> >>>>>
> >> >>>>> The samples were built OK now, but ftrace-direct-multi and
> >> >>>>> ftrace-direct-multi-modify report incorrect values of ip/pc it seems.
> >> >>>>>
> >> >>>>> I ran 'insmod ftrace-direct-multi.ko', waited a little and then checked
> >> >>>>> the messages in the trace:
> >> >>>>>
> >> >>>>> #           TASK-PID     CPU#  |||||  TIMESTAMP  FUNCTION
> >> >>>>> #              | |         |   |||||     |         |
> >> >>>>>         migration/1-19      [001] .....  3858.532131: my_direct_func1: my
> >> >>>>> direct func1 ip 0
> >> >>>>>         migration/0-15      [000] d.s2.  3858.532136: my_direct_func1: my
> >> >>>>> direct func1 ip ff60000001ba9600
> >> >>>>>         migration/0-15      [000] d..2.  3858.532204: my_direct_func1: my
> >> >>>>> direct func1 ip ff60000003334d00
> >> >>>>>         migration/0-15      [000] .....  3858.532232: my_direct_func1: my
> >> >>>>> direct func1 ip 0
> >> >>>>>           rcu_sched-14      [001] .....  3858.532257: my_direct_func1: my
> >> >>>>> direct func1 ip 0
> >> >>>>>              insmod-415     [000] .....  3858.532270: my_direct_func1: my
> >> >>>>> direct func1 ip 7fffffffffffffff
> >> >>>>>              <idle>-0       [001] ..s1.  3858.539051: my_direct_func1: my
> >> >>>>> direct func1 ip ff60000001ba9600
> >> >>>>>              <idle>-0       [001] dns2.  3858.539124: my_direct_func1: my
> >> >>>>> direct func1 ip ff60000001ba9600
> >> >>>>>           rcu_sched-14      [001] .....  3858.539208: my_direct_func1: my
> >> >>>>> direct func1 ip 0
> >> >>>>> [...]
> >> >>>>>
> >> >>>>> If I understand it right, my_direct_func1() should print the address of
> >> >>>>> some location in the code, probably - at the beginning of the traced
> >> >>>>> functions.
> >> >>>>>
> >> >>>>> The printed values (0x0, 0x7fffffffffffffff, ...) are not valid code
> >> >>>>> addresses.
> >> >>>>>
> >> >>>> The invalid code address is only printed by accessing the schedule()
> >> >>>> function's first argument whose address stores in a0 register.
> >> >>>> While schedule() actually has no parameter declared, so my_direct_func
> >> >>>> just prints the a0 in the context of the schedule()'s caller and
> >> >>>> the address maybe varies depending on the caller.
> >> >>>>
> >> >>>> I can't really understand why tracing the first argument of the
> >> >>>> schedule() function, but it seems nonsense at this point.
> >> >>>
> >> >>> The question is, what should be passed as the argument(s) of
> >> >>> my_direct_func() in this particular sample module. The kernel docs and
> >> >>> commit logs seem to contain no info on that.
> >> >>>
> >> >>> With direct functions, I suppose, the trampoline can pass anything it
> >> >>> wants to my_direct_func(), not just the arguments of the traced function.
> >> >>>
> >> >>> I'd check what these sample modules do on x86 and would try to match
> >> >>> that behaviour on RISC-V.
> >> >>
> >> >> I have checked ftrace-direct-multi.ko and ftrace-direct-multi-modify.ko
> >> >> on 6.2-rc4 built for x86-64 - yes, ip/pc in the traced function should
> >> >> be passed to my_direct_func().
> >> >>
> >> >> ftrace-direct-multi.ko:
> >> >> #           TASK-PID     CPU#  |||||  TIMESTAMP  FUNCTION
> >> >> #              | |         |   |||||     |         |
> >> >>             insmod-10829   [000] d.h1.  1719.518535: my_direct_func: ip
> >> >> ffffffff87332f45 // wake_up_process+0x5
> >> >>    rcu_tasks_kthre-11      [000] .....  1719.518696: my_direct_func: ip
> >> >> ffffffff8828d935 // schedule+0x5
> >> >>             insmod-10829   [000] .....  1719.518708: my_direct_func: ip
> >> >> ffffffff8828d935
> >> >>    systemd-journal-293     [001] .....  1719.518823: my_direct_func: ip
> >> >> ffffffff8828d935
> >> >>            systemd-1       [000] .....  1719.519141: my_direct_func: ip
> >> >> ffffffff8828d935
> >> >>             <idle>-0       [001] ..s1.  1719.521889: my_direct_func: ip
> >> >> ffffffff87332f45
> >> >>             <idle>-0       [000] d.s2.  1719.521901: my_direct_func: ip
> >> >> ffffffff87332f45
> >> >>        rcu_preempt-15      [001] .....  1719.521917: my_direct_func: ip
> >> >> ffffffff8828d935
> >> >> [...]
> >> >>
> >> >> The ip values are wake_up_process+0x5 and schedule+0x5, the locations
> >> >> where the execution of the traced functions resumes after the Ftrace
> >> >> trampoline has finished.
> >> >>
> >> >> The results with ftrace-direct-multi-modify.ko are similar to that.
> >> >>
> >> >> The samples look like a demonstration, that one can pass anything
> >> >> necessary to the handler in case of "direct" functions.
> >> >>
> >> >> I suppose, the RISC-V-specific asm code in these two sample modules
> >> >> could be updated to pass the saved pc value to my_direct_func() in a0.
> >> >
> >> > Yes, you're right.
> >> >
> >> > I added 'mv a0,t0' in front of `call my_direct_func` to pass the address of
> >> > traced function with mcount offset.
> >> >
> >> > Here is the updated patch for your reference.
> >> > https://github.com/sugarfillet/linux/commit/95b174fb104dd970b982ee6fa19879393e229318
> >>
> >> Thank you for the quick fix. This one looks good to me.
> >>
> >> ftrace-direct-multi*.ko now report the ip values corresponding to
> >> schedule+0x8 and wake_up_process+0x8, which is what was expected here.
> >>
> >> One more thing: please change my "Co-developed-by:" into "Tested-by:" in
> >> your patch, becase this is what I actually did: tested it and reported
> >> the results. I cannot take your credit for development of this patch ;-)
> >>
> >> Looking forward for v8 of the series.
> >> >
> >> >
> >> >>
> >> >>>
> >> >>>>
> >> >>>> As for this patch, it just impls a simple mcount (direct_caller) to
> >> >>>> trace kernel functions, and basically saves the necessary ABI,
> >> >>>> call the tracing function, and restores the ABI, just like other
> >> >>>> arches do.
> >> >>>> so It shouldn't be blamed.
> >> >>>>
> >> >>>> I started an independent patch to replace schedule with kick_process
> >> >>>> to make these samples more reasonable. And It has no conflict with the
> >> >>>> current patch, so we can go on.
> >> >>>>
> >> >>>> Link:
> >> >>>> https://lore.kernel.org/linux-kernel/20230117091101.3669996-1-suagrfillet@gmail.com/T/#u
> >> >>>>
> >> >>>>> The same issue is with ftrace-direct-multi-modify.ko.
> >> >>>>>
> >> >>>>> Is anything missing here?
> >> >>>>>
> >> >>>>>>
> >> >>>>>> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> >> >>>>>> index 307a9f413edd..e944af44f681 100644
> >> >>>>>> --- a/arch/riscv/Kconfig
> >> >>>>>> +++ b/arch/riscv/Kconfig
> >> >>>>>> @@ -112,6 +112,8 @@ config RISCV
> >> >>>>>>            select HAVE_POSIX_CPU_TIMERS_TASK_WORK
> >> >>>>>>            select HAVE_REGS_AND_STACK_ACCESS_API
> >> >>>>>>            select HAVE_FUNCTION_ARG_ACCESS_API
> >> >>>>>> +       select HAVE_SAMPLE_FTRACE_DIRECT
> >> >>>>>> +       select HAVE_SAMPLE_FTRACE_DIRECT_MULTI
> >> >>>>>>            select HAVE_STACKPROTECTOR
> >> >>>>>>            select HAVE_SYSCALL_TRACEPOINTS
> >> >>>>>>            select HAVE_RSEQ
> >> >>>>>> diff --git a/samples/ftrace/ftrace-direct-modify.c
> >> >>>>>> b/samples/ftrace/ftrace-direct-modify.c
> >> >>>>>> index de5a0f67f320..be7bf472c3c7 100644
> >> >>>>>> --- a/samples/ftrace/ftrace-direct-modify.c
> >> >>>>>> +++ b/samples/ftrace/ftrace-direct-modify.c
> >> >>>>>> @@ -23,6 +23,39 @@ extern void my_tramp2(void *);
> >> >>>>>>
> >> >>>>>>     static unsigned long my_ip = (unsigned long)schedule;
> >> >>>>>>
> >> >>>>>> +#ifdef CONFIG_RISCV
> >> >>>>>> +
> >> >>>>>> +asm (" .pushsection    .text, \"ax\", @progbits\n"
> >> >>>>>> +"      .type           my_tramp1, @function\n"
> >> >>>>>> +"      .globl          my_tramp1\n"
> >> >>>>>> +"   my_tramp1:\n"
> >> >>>>>> +"      addi sp,sp,-16\n"
> >> >>>>>> +"      sd   t0,0(sp)\n"
> >> >>>>>> +"      sd   ra,8(sp)\n"
> >> >>>>>> +"      call my_direct_func1\n"
> >> >>>>>> +"      ld   t0,0(sp)\n"
> >> >>>>>> +"      ld   ra,8(sp)\n"
> >> >>>>>> +"      addi sp,sp,16\n"
> >> >>>>>> +"      jr t0\n"
> >> >>>>>> +"      .size           my_tramp1, .-my_tramp1\n"
> >> >>>>>> +
> >> >>>>>> +"      .type           my_tramp2, @function\n"
> >> >>>>>> +"      .globl          my_tramp2\n"
> >> >>>>>> +"   my_tramp2:\n"
> >> >>>>>> +"      addi sp,sp,-16\n"
> >> >>>>>> +"      sd   t0,0(sp)\n"
> >> >>>>>> +"      sd   ra,8(sp)\n"
> >> >>>>>> +"      call my_direct_func2\n"
> >> >>>>>> +"      ld   t0,0(sp)\n"
> >> >>>>>> +"      ld   ra,8(sp)\n"
> >> >>>>>> +"      addi sp,sp,16\n"
> >> >>>>>> +"      jr t0\n"
> >> >>>>>> +"      .size           my_tramp2, .-my_tramp2\n"
> >> >>>>>> +"      .popsection\n"
> >> >>>>>> +);
> >> >>>>>> +
> >> >>>>>> +#endif /* CONFIG_RISCV */
> >> >>>>>> +
> >> >>>>>>     #ifdef CONFIG_X86_64
> >> >>>>>>
> >> >>>>>>     #include <asm/ibt.h>
> >> >>>>>> diff --git a/samples/ftrace/ftrace-direct-multi-modify.c
> >> >>>>>> b/samples/ftrace/ftrace-direct-multi-modify.c
> >> >>>>>> index d52370cad0b6..10884bf418f7 100644
> >> >>>>>> --- a/samples/ftrace/ftrace-direct-multi-modify.c
> >> >>>>>> +++ b/samples/ftrace/ftrace-direct-multi-modify.c
> >> >>>>>> @@ -21,6 +21,43 @@ void my_direct_func2(unsigned long ip)
> >> >>>>>>     extern void my_tramp1(void *);
> >> >>>>>>     extern void my_tramp2(void *);
> >> >>>>>>
> >> >>>>>> +#ifdef CONFIG_RISCV
> >> >>>>>> +
> >> >>>>>> +asm (" .pushsection    .text, \"ax\", @progbits\n"
> >> >>>>>> +"      .type           my_tramp1, @function\n"
> >> >>>>>> +"      .globl          my_tramp1\n"
> >> >>>>>> +"   my_tramp1:\n"
> >> >>>>>> +"       addi sp,sp,-24\n"
> >> >>>>>> +"       sd   a0,0(sp)\n"
> >> >>>>>> +"       sd   t0,8(sp)\n"
> >> >>>>>> +"       sd   ra,16(sp)\n"
> >> >>>>>> +"       call my_direct_func1\n"
> >> >>>>>> +"       ld   a0,0(sp)\n"
> >> >>>>>> +"       ld   t0,8(sp)\n"
> >> >>>>>> +"       ld   ra,16(sp)\n"
> >> >>>>>> +"       addi sp,sp,24\n"
> >> >>>>>> +"      jr t0\n"
> >> >>>>>> +"      .size           my_tramp1, .-my_tramp1\n"
> >> >>>>>> +
> >> >>>>>> +"      .type           my_tramp2, @function\n"
> >> >>>>>> +"      .globl          my_tramp2\n"
> >> >>>>>> +"   my_tramp2:\n"
> >> >>>>>> +"       addi sp,sp,-24\n"
> >> >>>>>> +"       sd   a0,0(sp)\n"
> >> >>>>>> +"       sd   t0,8(sp)\n"
> >> >>>>>> +"       sd   ra,16(sp)\n"
> >> >>>>>> +"       call my_direct_func2\n"
> >> >>>>>> +"       ld   a0,0(sp)\n"
> >> >>>>>> +"       ld   t0,8(sp)\n"
> >> >>>>>> +"       ld   ra,16(sp)\n"
> >> >>>>>> +"       addi sp,sp,24\n"
> >> >>>>>> +"      jr t0\n"
> >> >>>>>> +"      .size           my_tramp2, .-my_tramp2\n"
> >> >>>>>> +"      .popsection\n"
> >> >>>>>> +);
> >> >>>>>> +
> >> >>>>>> +#endif /* CONFIG_RISCV */
> >> >>>>>> +
> >> >>>>>>     #ifdef CONFIG_X86_64
> >> >>>>>>
> >> >>>>>>     #include <asm/ibt.h>
> >> >>>>>> diff --git a/samples/ftrace/ftrace-direct-multi.c
> >> >>>>>> b/samples/ftrace/ftrace-direct-multi.c
> >> >>>>>> index ec1088922517..a35bf43bf6d7 100644
> >> >>>>>> --- a/samples/ftrace/ftrace-direct-multi.c
> >> >>>>>> +++ b/samples/ftrace/ftrace-direct-multi.c
> >> >>>>>> @@ -16,6 +16,28 @@ void my_direct_func(unsigned long ip)
> >> >>>>>>
> >> >>>>>>     extern void my_tramp(void *);
> >> >>>>>>
> >> >>>>>> +#ifdef CONFIG_RISCV
> >> >>>>>> +
> >> >>>>>> +asm ("       .pushsection    .text, \"ax\", @progbits\n"
> >> >>>>>> +"       .type           my_tramp, @function\n"
> >> >>>>>> +"       .globl          my_tramp\n"
> >> >>>>>> +"   my_tramp:\n"
> >> >>>>>> +"       addi sp,sp,-24\n"
> >> >>>>>> +"       sd   a0,0(sp)\n"
> >> >>>>>> +"       sd   t0,8(sp)\n"
> >> >>>>>> +"       sd   ra,16(sp)\n"
> >> >>>>>> +"       call my_direct_func\n"
> >> >>>>>> +"       ld   a0,0(sp)\n"
> >> >>>>>> +"       ld   t0,8(sp)\n"
> >> >>>>>> +"       ld   ra,16(sp)\n"
> >> >>>>>> +"       addi sp,sp,24\n"
> >> >>>>>> +"       jr t0\n"
> >> >>>>>> +"       .size           my_tramp, .-my_tramp\n"
> >> >>>>>> +"       .popsection\n"
> >> >>>>>> +);
> >> >>>>>> +
> >> >>>>>> +#endif /* CONFIG_RISCV */
> >> >>>>>> +
> >> >>>>>>     #ifdef CONFIG_X86_64
> >> >>>>>>
> >> >>>>>>     #include <asm/ibt.h>
> >> >>>>>> diff --git a/samples/ftrace/ftrace-direct-too.c
> >> >>>>>> b/samples/ftrace/ftrace-direct-too.c
> >> >>>>>> index e13fb59a2b47..3b62e33c2e6d 100644
> >> >>>>>> --- a/samples/ftrace/ftrace-direct-too.c
> >> >>>>>> +++ b/samples/ftrace/ftrace-direct-too.c
> >> >>>>>> @@ -18,6 +18,32 @@ void my_direct_func(struct vm_area_struct *vma,
> >> >>>>>>
> >> >>>>>>     extern void my_tramp(void *);
> >> >>>>>>
> >> >>>>>> +#ifdef CONFIG_RISCV
> >> >>>>>> +
> >> >>>>>> +asm ("       .pushsection    .text, \"ax\", @progbits\n"
> >> >>>>>> +"       .type           my_tramp, @function\n"
> >> >>>>>> +"       .globl          my_tramp\n"
> >> >>>>>> +"   my_tramp:\n"
> >> >>>>>> +"       addi sp,sp,-40\n"
> >> >>>>>> +"       sd   a0,0(sp)\n"
> >> >>>>>> +"       sd   a1,8(sp)\n"
> >> >>>>>> +"       sd   a2,16(sp)\n"
> >> >>>>>> +"       sd   t0,24(sp)\n"
> >> >>>>>> +"       sd   ra,32(sp)\n"
> >> >>>>>> +"       call my_direct_func\n"
> >> >>>>>> +"       ld   a0,0(sp)\n"
> >> >>>>>> +"       ld   a1,8(sp)\n"
> >> >>>>>> +"       ld   a2,16(sp)\n"
> >> >>>>>> +"       ld   t0,24(sp)\n"
> >> >>>>>> +"       ld   ra,32(sp)\n"
> >> >>>>>> +"       addi sp,sp,40\n"
> >> >>>>>> +"       jr t0\n"
> >> >>>>>> +"       .size           my_tramp, .-my_tramp\n"
> >> >>>>>> +"       .popsection\n"
> >> >>>>>> +);
> >> >>>>>> +
> >> >>>>>> +#endif /* CONFIG_RISCV */
> >> >>>>>> +
> >> >>>>>>     #ifdef CONFIG_X86_64
> >> >>>>>>
> >> >>>>>>     #include <asm/ibt.h>
> >> >>>>>> diff --git a/samples/ftrace/ftrace-direct.c
> >> >>>>>> b/samples/ftrace/ftrace-direct.c
> >> >>>>>> index 1f769d0db20f..2cfe5a7d2d70 100644
> >> >>>>>> --- a/samples/ftrace/ftrace-direct.c
> >> >>>>>> +++ b/samples/ftrace/ftrace-direct.c
> >> >>>>>> @@ -15,6 +15,28 @@ void my_direct_func(struct task_struct *p)
> >> >>>>>>
> >> >>>>>>     extern void my_tramp(void *);
> >> >>>>>>
> >> >>>>>> +#ifdef CONFIG_RISCV
> >> >>>>>> +
> >> >>>>>> +asm ("       .pushsection    .text, \"ax\", @progbits\n"
> >> >>>>>> +"       .type           my_tramp, @function\n"
> >> >>>>>> +"       .globl          my_tramp\n"
> >> >>>>>> +"   my_tramp:\n"
> >> >>>>>> +"       addi sp,sp,-24\n"
> >> >>>>>> +"       sd   a0,0(sp)\n"
> >> >>>>>> +"       sd   t0,8(sp)\n"
> >> >>>>>> +"       sd   ra,16(sp)\n"
> >> >>>>>> +"       call my_direct_func\n"
> >> >>>>>> +"       ld   a0,0(sp)\n"
> >> >>>>>> +"       ld   t0,8(sp)\n"
> >> >>>>>> +"       ld   ra,16(sp)\n"
> >> >>>>>> +"       addi sp,sp,24\n"
> >> >>>>>> +"       jr t0\n"
> >> >>>>>> +"       .size           my_tramp, .-my_tramp\n"
> >> >>>>>> +"       .popsection\n"
> >> >>>>>> +);
> >> >>>>>> +
> >> >>>>>> +#endif /* CONFIG_RISCV */
> >> >>>>>> +
> >> >>>>>>     #ifdef CONFIG_X86_64
> >> >>>>>>
> >> >>>>>>     #include <asm/ibt.h>
> >> >>>>>> --
> >> >>>>>> 2.36.1
> >> >>>>
> >> >>>> --
> >> >>>> Thanks,
> >> >>>> Song
> >> >>>>
> >> >>>
> >> >>> Regards,
> >> >>> Evgenii
> >> >>
> >> >>
> >> >
> >> >
> >> > --
> >> > Thanks,
> >> > Song
> >> >
> >>
> >>
> >
> >
> > --
> > Best Regards
> >  Guo Ren