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 <[email protected]>
---
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)
--
2.31.1
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 <[email protected]>
> ---
> 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)
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 <[email protected]>
>> ---
>> 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)