diff mbox series

[04/11] s390: vmlinux.lds.S: Discard unnecessary sections

Message ID 20240207-s390-lld-and-orphan-warn-v1-4-8a665b3346ab@kernel.org
State New
Headers
Series [01/11] s390: boot: Add support for CONFIG_LD_ORPHAN_WARN |

Commit Message

Nathan Chancellor Feb. 8, 2024, 12:14 a.m. UTC 
  When building with CONFIG_LD_ORPHAN_WARN after selecting
CONFIG_ARCH_HAS_LD_ORPHAN_WARN, there are some warnings around certain
ELF sections that are unnecessary for the kernel's purposes.

  s390-linux-ld: warning: orphan section `.dynstr' from `arch/s390/kernel/head64.o' being placed in section `.dynstr'
  s390-linux-ld: warning: orphan section `.dynamic' from `arch/s390/kernel/head64.o' being placed in section `.dynamic'
  s390-linux-ld: warning: orphan section `.hash' from `arch/s390/kernel/head64.o' being placed in section `.hash'
  s390-linux-ld: warning: orphan section `.gnu.hash' from `arch/s390/kernel/head64.o' being placed in section `.gnu.hash'

Add them to the discards to clear up the warnings, which matches other
architectures.

Signed-off-by: Nathan Chancellor <nathan@kernel.org>
---
 arch/s390/kernel/vmlinux.lds.S | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

Comments

Heiko Carstens Feb. 12, 2024, 1:55 p.m. UTC | #1 
On Wed, Feb 07, 2024 at 05:14:56PM -0700, Nathan Chancellor wrote:
> When building with CONFIG_LD_ORPHAN_WARN after selecting
> CONFIG_ARCH_HAS_LD_ORPHAN_WARN, there are some warnings around certain
> ELF sections that are unnecessary for the kernel's purposes.
> 
>   s390-linux-ld: warning: orphan section `.dynstr' from `arch/s390/kernel/head64.o' being placed in section `.dynstr'
>   s390-linux-ld: warning: orphan section `.dynamic' from `arch/s390/kernel/head64.o' being placed in section `.dynamic'
>   s390-linux-ld: warning: orphan section `.hash' from `arch/s390/kernel/head64.o' being placed in section `.hash'
>   s390-linux-ld: warning: orphan section `.gnu.hash' from `arch/s390/kernel/head64.o' being placed in section `.gnu.hash'
> 
> Add them to the discards to clear up the warnings, which matches other
> architectures.
> 
> Signed-off-by: Nathan Chancellor <nathan@kernel.org>
> ---
>  arch/s390/kernel/vmlinux.lds.S | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
..
> -		*(.interp)
> +		*(.interp .dynamic)
> +		*(.dynstr .hash .gnu.hash)

This seems to be wrong, since it leads to 1000s of error messages when
using the "crash" utility e.g. when looking into a live dump of system
with the generated debug info:

BFD: /usr/lib/debug/usr/lib/modules/6.8.0-20240211.rc3.git0.bdca9b8dcf3f.300.fc39.s390x/vmlinux: attempt to load strings from a non-string section (number 0)

I will change this commit to the below; it seems to work and is in
line with other architectures:

-----

When building with CONFIG_LD_ORPHAN_WARN after selecting
CONFIG_ARCH_HAS_LD_ORPHAN_WARN, there are some warnings around certain
ELF sections:

  s390-linux-ld: warning: orphan section `.dynstr' from `arch/s390/kernel/head64.o' being placed in section `.dynstr'
  s390-linux-ld: warning: orphan section `.dynamic' from `arch/s390/kernel/head64.o' being placed in section `.dynamic'
  s390-linux-ld: warning: orphan section `.hash' from `arch/s390/kernel/head64.o' being placed in section `.hash'
  s390-linux-ld: warning: orphan section `.gnu.hash' from `arch/s390/kernel/head64.o' being placed in section `.gnu.hash'

Explicitly keep those sections like other architectures when
CONFIG_RELOCATABLE is enabled, which is always true for s390.

[hca@linux.ibm.com: keep sections instead of discarding]
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Link: https://lore.kernel.org/r/20240207-s390-lld-and-orphan-warn-v1-4-8a665b3346ab@kernel.org
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
---
 arch/s390/kernel/vmlinux.lds.S | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/arch/s390/kernel/vmlinux.lds.S b/arch/s390/kernel/vmlinux.lds.S
index 661a487a3048..d46e3c383952 100644
--- a/arch/s390/kernel/vmlinux.lds.S
+++ b/arch/s390/kernel/vmlinux.lds.S
@@ -200,6 +200,21 @@ SECTIONS
 		*(.rela*)
 		__rela_dyn_end = .;
 	}
+	.dynamic ALIGN(8) : {
+		*(.dynamic)
+	}
+	.dynsym ALIGN(8) : {
+		*(.dynsym)
+	}
+	.dynstr ALIGN(8) : {
+		*(.dynstr)
+	}
+	.hash ALIGN(8) : {
+		*(.hash)
+	}
+	.gnu.hash ALIGN(8) : {
+		*(.gnu.hash)
+	}
 
 	. = ALIGN(PAGE_SIZE);
 	__init_end = .;		/* freed after init ends here */
Heiko Carstens Feb. 12, 2024, 3:19 p.m. UTC | #2 
On Mon, Feb 12, 2024 at 02:55:11PM +0100, Heiko Carstens wrote:
> Explicitly keep those sections like other architectures when
> CONFIG_RELOCATABLE is enabled, which is always true for s390.
..
> +	.dynstr ALIGN(8) : {
> +		*(.dynstr)
> +	}

Except for this, which is already present (copy-paste-error).
Nathan Chancellor Feb. 13, 2024, 12:15 a.m. UTC | #3 
On Mon, Feb 12, 2024 at 02:55:11PM +0100, Heiko Carstens wrote:
> On Wed, Feb 07, 2024 at 05:14:56PM -0700, Nathan Chancellor wrote:
> > When building with CONFIG_LD_ORPHAN_WARN after selecting
> > CONFIG_ARCH_HAS_LD_ORPHAN_WARN, there are some warnings around certain
> > ELF sections that are unnecessary for the kernel's purposes.
> > 
> >   s390-linux-ld: warning: orphan section `.dynstr' from `arch/s390/kernel/head64.o' being placed in section `.dynstr'
> >   s390-linux-ld: warning: orphan section `.dynamic' from `arch/s390/kernel/head64.o' being placed in section `.dynamic'
> >   s390-linux-ld: warning: orphan section `.hash' from `arch/s390/kernel/head64.o' being placed in section `.hash'
> >   s390-linux-ld: warning: orphan section `.gnu.hash' from `arch/s390/kernel/head64.o' being placed in section `.gnu.hash'
> > 
> > Add them to the discards to clear up the warnings, which matches other
> > architectures.
> > 
> > Signed-off-by: Nathan Chancellor <nathan@kernel.org>
> > ---
> >  arch/s390/kernel/vmlinux.lds.S | 3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> ...
> > -		*(.interp)
> > +		*(.interp .dynamic)
> > +		*(.dynstr .hash .gnu.hash)
> 
> This seems to be wrong, since it leads to 1000s of error messages when
> using the "crash" utility e.g. when looking into a live dump of system
> with the generated debug info:
> 
> BFD: /usr/lib/debug/usr/lib/modules/6.8.0-20240211.rc3.git0.bdca9b8dcf3f.300.fc39.s390x/vmlinux: attempt to load strings from a non-string section (number 0)
> 
> I will change this commit to the below; it seems to work and is in
> line with other architectures:

Thanks a lot for catching that, your final change seems good to me.
Here's to hoping I did not get anything else wrong :)

Cheers,
Nathan

> -----
> 
> When building with CONFIG_LD_ORPHAN_WARN after selecting
> CONFIG_ARCH_HAS_LD_ORPHAN_WARN, there are some warnings around certain
> ELF sections:
> 
>   s390-linux-ld: warning: orphan section `.dynstr' from `arch/s390/kernel/head64.o' being placed in section `.dynstr'
>   s390-linux-ld: warning: orphan section `.dynamic' from `arch/s390/kernel/head64.o' being placed in section `.dynamic'
>   s390-linux-ld: warning: orphan section `.hash' from `arch/s390/kernel/head64.o' being placed in section `.hash'
>   s390-linux-ld: warning: orphan section `.gnu.hash' from `arch/s390/kernel/head64.o' being placed in section `.gnu.hash'
> 
> Explicitly keep those sections like other architectures when
> CONFIG_RELOCATABLE is enabled, which is always true for s390.
> 
> [hca@linux.ibm.com: keep sections instead of discarding]
> Signed-off-by: Nathan Chancellor <nathan@kernel.org>
> Link: https://lore.kernel.org/r/20240207-s390-lld-and-orphan-warn-v1-4-8a665b3346ab@kernel.org
> Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
> ---
>  arch/s390/kernel/vmlinux.lds.S | 15 +++++++++++++++
>  1 file changed, 15 insertions(+)
> 
> diff --git a/arch/s390/kernel/vmlinux.lds.S b/arch/s390/kernel/vmlinux.lds.S
> index 661a487a3048..d46e3c383952 100644
> --- a/arch/s390/kernel/vmlinux.lds.S
> +++ b/arch/s390/kernel/vmlinux.lds.S
> @@ -200,6 +200,21 @@ SECTIONS
>  		*(.rela*)
>  		__rela_dyn_end = .;
>  	}
> +	.dynamic ALIGN(8) : {
> +		*(.dynamic)
> +	}
> +	.dynsym ALIGN(8) : {
> +		*(.dynsym)
> +	}
> +	.dynstr ALIGN(8) : {
> +		*(.dynstr)
> +	}
> +	.hash ALIGN(8) : {
> +		*(.hash)
> +	}
> +	.gnu.hash ALIGN(8) : {
> +		*(.gnu.hash)
> +	}
>  
>  	. = ALIGN(PAGE_SIZE);
>  	__init_end = .;		/* freed after init ends here */
> -- 
> 2.40.1
>
diff mbox series

Patch

diff --git a/arch/s390/kernel/vmlinux.lds.S b/arch/s390/kernel/vmlinux.lds.S
index 661a487a3048..35a6b3e6cc50 100644
--- a/arch/s390/kernel/vmlinux.lds.S
+++ b/arch/s390/kernel/vmlinux.lds.S
@@ -264,6 +264,7 @@  SECTIONS
 	DISCARDS
 	/DISCARD/ : {
 		*(.eh_frame)
-		*(.interp)
+		*(.interp .dynamic)
+		*(.dynstr .hash .gnu.hash)
 	}
 }