diff mbox series

[v2,02/13] x86/kexec: refactor for kernel/Kconfig.kexec

Message ID 20230619145801.1064716-3-eric.devolder@oracle.com
State New
Headers
Series refactor Kconfig to consolidate KEXEC and CRASH options |

Commit Message

Eric DeVolder June 19, 2023, 2:57 p.m. UTC 
  The kexec and crash kernel options are provided in the common
kernel/Kconfig.kexec. Utilize the common options and provide
the ARCH_SUPPORTS_ and ARCH_SELECTS_ entries to recreate the
equivalent set of KEXEC and CRASH options.

Signed-off-by: Eric DeVolder <eric.devolder@oracle.com>
---
 arch/x86/Kconfig | 89 +++++++-----------------------------------------
 1 file changed, 13 insertions(+), 76 deletions(-)

Comments

Baoquan He June 20, 2023, 8:21 a.m. UTC | #1 
Hi Eric,

On 06/19/23 at 10:57am, Eric DeVolder wrote:
......
> +config ARCH_SUPPORTS_KEXEC
> +	def_bool y
>  
> -config ARCH_HAS_KEXEC_PURGATORY
> -	def_bool KEXEC_FILE
> +config ARCH_SUPPORTS_KEXEC_FILE
> +	def_bool X86_64 && CRYPTO && CRYPTO_SHA256
......  
> +config ARCH_SELECTS_KEXEC_FILE
> +	def_bool y
>  	depends on KEXEC_FILE
> -	help

I am a little confused about this ARCH_SELECTS_XX adding. Wondering what
limits us defining the ARCH_SUPPORTS_KEXEC_FILE like below? I have limited
knowledge about Kconfig, please correct me if I am wrong. Thanks in
advance.

 +config ARCH_SUPPORTS_KEXEC_FILE
 +	def_bool y
  	depends on KEXEC_FILE
  	depends on X86_64 && CRYPTO && CRYPTO_SHA256

> -
> -	  This option makes the kexec_file_load() syscall check for a valid
> -	  signature of the kernel image.  The image can still be loaded without
> -	  a valid signature unless you also enable KEXEC_SIG_FORCE, though if
> -	  there's a signature that we can check, then it must be valid.
> -
> -	  In addition to this option, you need to enable signature
> -	  verification for the corresponding kernel image type being
> -	  loaded in order for this to work.
> -
Eric DeVolder June 20, 2023, 12:56 p.m. UTC | #2 
On 6/20/23 03:21, Baoquan He wrote:
> Hi Eric,
> 
> On 06/19/23 at 10:57am, Eric DeVolder wrote:
> ......
>> +config ARCH_SUPPORTS_KEXEC
>> +	def_bool y
>>   
>> -config ARCH_HAS_KEXEC_PURGATORY
>> -	def_bool KEXEC_FILE
>> +config ARCH_SUPPORTS_KEXEC_FILE
>> +	def_bool X86_64 && CRYPTO && CRYPTO_SHA256
> ......
>> +config ARCH_SELECTS_KEXEC_FILE
>> +	def_bool y
>>   	depends on KEXEC_FILE
>> -	help
> 
> I am a little confused about this ARCH_SELECTS_XX adding. Wondering what
> limits us defining the ARCH_SUPPORTS_KEXEC_FILE like below? I have limited
> knowledge about Kconfig, please correct me if I am wrong. Thanks in
> advance.
> 
>   +config ARCH_SUPPORTS_KEXEC_FILE
>   +	def_bool y
>    	depends on KEXEC_FILE
>    	depends on X86_64 && CRYPTO && CRYPTO_SHA256
> 

For the ARCH_SUPPORTS_ options, I chose to list the dependencies on the def_bool line to show that 
it took all those conditions to result in True.
However, as you point out, using a def_bool y and then listing them as 'depends on' works as well.
Probably would have resulted in fewer changes to the Kconfig file.
Either way is ok (the 'depends on KEXEC_FILE' is erroneous in your example).
eric


>> -
>> -	  This option makes the kexec_file_load() syscall check for a valid
>> -	  signature of the kernel image.  The image can still be loaded without
>> -	  a valid signature unless you also enable KEXEC_SIG_FORCE, though if
>> -	  there's a signature that we can check, then it must be valid.
>> -
>> -	  In addition to this option, you need to enable signature
>> -	  verification for the corresponding kernel image type being
>> -	  loaded in order for this to work.
>> -
>
Baoquan He June 20, 2023, 2:49 p.m. UTC | #3 
On 06/20/23 at 07:56am, Eric DeVolder wrote:
> 
> 
> On 6/20/23 03:21, Baoquan He wrote:
> > Hi Eric,
> > 
> > On 06/19/23 at 10:57am, Eric DeVolder wrote:
> > ......
> > > +config ARCH_SUPPORTS_KEXEC
> > > +	def_bool y
> > > -config ARCH_HAS_KEXEC_PURGATORY
> > > -	def_bool KEXEC_FILE
> > > +config ARCH_SUPPORTS_KEXEC_FILE
> > > +	def_bool X86_64 && CRYPTO && CRYPTO_SHA256
> > ......
> > > +config ARCH_SELECTS_KEXEC_FILE
> > > +	def_bool y
> > >   	depends on KEXEC_FILE
> > > -	help
> > 
> > I am a little confused about this ARCH_SELECTS_XX adding. Wondering what
> > limits us defining the ARCH_SUPPORTS_KEXEC_FILE like below? I have limited
> > knowledge about Kconfig, please correct me if I am wrong. Thanks in
> > advance.
> > 
> >   +config ARCH_SUPPORTS_KEXEC_FILE
> >   +	def_bool y
> >    	depends on KEXEC_FILE
> >    	depends on X86_64 && CRYPTO && CRYPTO_SHA256
> > 
> 
> For the ARCH_SUPPORTS_ options, I chose to list the dependencies on the
> def_bool line to show that it took all those conditions to result in True.
> However, as you point out, using a def_bool y and then listing them as 'depends on' works as well.
> Probably would have resulted in fewer changes to the Kconfig file.
> Either way is ok (the 'depends on KEXEC_FILE' is erroneous in your example).

Got it, thanks. To me, one option with explicit dependencies looks clearer
and straightforward. I need check and investigage why two options are needed,
whether two options are unavoidable. Not sure if other people would get
the same feeling or not. Honestly, it's my first time to see the usage of
XXX_SELECTS_XXX, it took me a while to dig into.

> 
> > > -
> > > -	  This option makes the kexec_file_load() syscall check for a valid
> > > -	  signature of the kernel image.  The image can still be loaded without
> > > -	  a valid signature unless you also enable KEXEC_SIG_FORCE, though if
> > > -	  there's a signature that we can check, then it must be valid.
> > > -
> > > -	  In addition to this option, you need to enable signature
> > > -	  verification for the corresponding kernel image type being
> > > -	  loaded in order for this to work.
> > > -
> > 
>
diff mbox series

Patch

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 53bab123a8ee..1afc6ca2986b 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -2043,88 +2043,25 @@  config EFI_RUNTIME_MAP
 
 source "kernel/Kconfig.hz"
 
-config KEXEC
-	bool "kexec system call"
-	select KEXEC_CORE
-	help
-	  kexec is a system call that implements the ability to shutdown your
-	  current kernel, and to start another kernel.  It is like a reboot
-	  but it is independent of the system firmware.   And like a reboot
-	  you can start any kernel with it, not just Linux.
-
-	  The name comes from the similarity to the exec system call.
-
-	  It is an ongoing process to be certain the hardware in a machine
-	  is properly shutdown, so do not be surprised if this code does not
-	  initially work for you.  As of this writing the exact hardware
-	  interface is strongly in flux, so no good recommendation can be
-	  made.
-
-config KEXEC_FILE
-	bool "kexec file based system call"
-	select KEXEC_CORE
-	select HAVE_IMA_KEXEC if IMA
-	depends on X86_64
-	depends on CRYPTO=y
-	depends on CRYPTO_SHA256=y
-	help
-	  This is new version of kexec system call. This system call is
-	  file based and takes file descriptors as system call argument
-	  for kernel and initramfs as opposed to list of segments as
-	  accepted by previous system call.
+config ARCH_SUPPORTS_KEXEC
+	def_bool y
 
-config ARCH_HAS_KEXEC_PURGATORY
-	def_bool KEXEC_FILE
+config ARCH_SUPPORTS_KEXEC_FILE
+	def_bool X86_64 && CRYPTO && CRYPTO_SHA256
 
-config KEXEC_SIG
-	bool "Verify kernel signature during kexec_file_load() syscall"
+config ARCH_SELECTS_KEXEC_FILE
+	def_bool y
 	depends on KEXEC_FILE
-	help
-
-	  This option makes the kexec_file_load() syscall check for a valid
-	  signature of the kernel image.  The image can still be loaded without
-	  a valid signature unless you also enable KEXEC_SIG_FORCE, though if
-	  there's a signature that we can check, then it must be valid.
-
-	  In addition to this option, you need to enable signature
-	  verification for the corresponding kernel image type being
-	  loaded in order for this to work.
-
-config KEXEC_SIG_FORCE
-	bool "Require a valid signature in kexec_file_load() syscall"
-	depends on KEXEC_SIG
-	help
-	  This option makes kernel signature verification mandatory for
-	  the kexec_file_load() syscall.
+	select HAVE_IMA_KEXEC if IMA
 
-config KEXEC_BZIMAGE_VERIFY_SIG
-	bool "Enable bzImage signature verification support"
-	depends on KEXEC_SIG
-	depends on SIGNED_PE_FILE_VERIFICATION
-	select SYSTEM_TRUSTED_KEYRING
-	help
-	  Enable bzImage signature verification support.
+config ARCH_HAS_KEXEC_PURGATORY
+	def_bool KEXEC_FILE
 
-config CRASH_DUMP
-	bool "kernel crash dumps"
-	depends on X86_64 || (X86_32 && HIGHMEM)
-	help
-	  Generate crash dump after being started by kexec.
-	  This should be normally only set in special crash dump kernels
-	  which are loaded in the main kernel with kexec-tools into
-	  a specially reserved region and then later executed after
-	  a crash by kdump/kexec. The crash dump kernel must be compiled
-	  to a memory address not used by the main kernel or BIOS using
-	  PHYSICAL_START, or it must be built as a relocatable image
-	  (CONFIG_RELOCATABLE=y).
-	  For more details see Documentation/admin-guide/kdump/kdump.rst
+config ARCH_SUPPORTS_KEXEC_JUMP
+	def_bool y
 
-config KEXEC_JUMP
-	bool "kexec jump"
-	depends on KEXEC && HIBERNATION
-	help
-	  Jump between original kernel and kexeced kernel and invoke
-	  code in physical address mode via KEXEC
+config ARCH_SUPPORTS_CRASH_DUMP
+	def_bool X86_64 || (X86_32 && HIGHMEM)
 
 config PHYSICAL_START
 	hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)