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@xxxxxxxxxx> --- 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_MAPsource "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_STARThex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
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