diff mbox series

[v5,02/13] x86/kexec: refactor for kernel/Kconfig.kexec

Message ID 20230706222027.189117-3-eric.devolder@oracle.com (mailing list archive)
State New, archived
Headers show
Series refactor Kconfig to consolidate KEXEC and CRASH options | expand

Commit Message

Eric DeVolder July 6, 2023, 10:20 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 | 92 ++++++++++--------------------------------------
 1 file changed, 19 insertions(+), 73 deletions(-)

Comments

Christophe Leroy July 7, 2023, 5:58 a.m. UTC | #1
Le 07/07/2023 à 00:20, Eric DeVolder a écrit :
> 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.


Why do you need to duplicate the ARCH_SELECTS_ entries in each 
architecture ?

Why not define them in arch/Kconfig then select if from each architecture ?

For instance here for x86 for ARCH_SELECTS_KEXEC_FILE all you'll have to 
do is:
	select ARCH_SELECTS_KEXEC_FILE if KEXEC_FILE
	select HAVE_IMA_KEXEC if IMA && KEXEC_FILE


Christophe

> 
> Signed-off-by: Eric DeVolder <eric.devolder@oracle.com>
> ---
>   arch/x86/Kconfig | 92 ++++++++++--------------------------------------
>   1 file changed, 19 insertions(+), 73 deletions(-)
> 
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index 7422db409770..9767a343f7c2 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -2040,88 +2040,34 @@ 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
> +	select HAVE_IMA_KEXEC if IMA
>   
> -	  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.
> +config ARCH_HAS_KEXEC_PURGATORY
> +	def_bool KEXEC_FILE
>   
> -	  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 ARCH_SUPPORTS_KEXEC_SIG
> +	def_bool y
>   
> -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.
> +config ARCH_SUPPORTS_KEXEC_SIG_FORCE
> +	def_bool y
>   
> -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_SUPPORTS_KEXEC_BZIMAGE_VERIFY_SIG
> +	def_bool y
>   
> -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)
Eric DeVolder July 7, 2023, 12:16 p.m. UTC | #2
On 7/7/23 00:58, Christophe Leroy wrote:
> 
> 
> Le 07/07/2023 à 00:20, Eric DeVolder a écrit :
>> 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.
> 
> 
> Why do you need to duplicate the ARCH_SELECTS_ entries in each
> architecture ?
> 
> Why not define them in arch/Kconfig then select if from each architecture ?
> 
> For instance here for x86 for ARCH_SELECTS_KEXEC_FILE all you'll have to
> do is:
> 	select ARCH_SELECTS_KEXEC_FILE if KEXEC_FILE
> 	select HAVE_IMA_KEXEC if IMA && KEXEC_FILE
> 
> 
> Christophe

Hi Christophe, thanks for looking at this!
The ARCH_SELECTS_ is where the "customization" is performed for that option. The customization is 
putting in place the differences that the arch had from the common option.

For example, with ARCH_SELECTS_KEXEC_FILE, here are all the uses:

x86:
     select HAVE_IMA_KEXEC if IMA

arm64:
     select HAVE_IMA_KEXEC if IMA

powerpc:
     select KEXEC_ELF
     select HAVE_IMA_KEXEC if IMA

riscv:
     select HAVE_IMA_KEXEC if IMA
     select KEXEC_ELF

And there are archs (parisc, riscv, s390) that support KEXEC_FILE that do not need 
ARCH_SELECTS_KEXEC_FILE.

So there isn't a clear path for optimizing the IMA statement, in this example, that I'm aware of.

But perhaps I don't quite understand the technique you are suggesting, either...

eric



> 
>>
>> Signed-off-by: Eric DeVolder <eric.devolder@oracle.com>
>> ---
>>    arch/x86/Kconfig | 92 ++++++++++--------------------------------------
>>    1 file changed, 19 insertions(+), 73 deletions(-)
>>
>> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
>> index 7422db409770..9767a343f7c2 100644
>> --- a/arch/x86/Kconfig
>> +++ b/arch/x86/Kconfig
>> @@ -2040,88 +2040,34 @@ 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
>> +	select HAVE_IMA_KEXEC if IMA
>>    
>> -	  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.
>> +config ARCH_HAS_KEXEC_PURGATORY
>> +	def_bool KEXEC_FILE
>>    
>> -	  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 ARCH_SUPPORTS_KEXEC_SIG
>> +	def_bool y
>>    
>> -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.
>> +config ARCH_SUPPORTS_KEXEC_SIG_FORCE
>> +	def_bool y
>>    
>> -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_SUPPORTS_KEXEC_BZIMAGE_VERIFY_SIG
>> +	def_bool y
>>    
>> -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)
diff mbox series

Patch

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 7422db409770..9767a343f7c2 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -2040,88 +2040,34 @@  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
+	select HAVE_IMA_KEXEC if IMA
 
-	  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.
+config ARCH_HAS_KEXEC_PURGATORY
+	def_bool KEXEC_FILE
 
-	  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 ARCH_SUPPORTS_KEXEC_SIG
+	def_bool y
 
-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.
+config ARCH_SUPPORTS_KEXEC_SIG_FORCE
+	def_bool y
 
-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_SUPPORTS_KEXEC_BZIMAGE_VERIFY_SIG
+	def_bool y
 
-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)