Re: [PATCH v3 5/5] powerpc: kcsan: Add KCSAN Support

[Christophe Leroy <christophe.leroy@csgroup.eu>]

Le 06/02/2023 à 03:18, Rohan McLure a écrit :
> Enable HAVE_ARCH_KCSAN on all powerpc platforms, permitting use of the
> kernel concurrency sanitiser through the CONFIG_KCSAN_* kconfig options.
> KCSAN requires compiler builtins __atomic_* 64-bit values, and so only
> report support on PPC64.
> 
> See documentation in Documentation/dev-tools/kcsan.rst for more
> information.
> 
> Signed-off-by: Rohan McLure <rmclure@linux.ibm.com>
> ---
> v3: Restrict support to 64-bit, as TSAN expects 64-bit __atomic_* compiler
> built-ins.

Support for PPC32 should be kept.

See commit 725aea873261 ("xtensa: enable KCSAN")
xtensa is a 32 bits architecture, they have implemented stubs for 64-bit 
atomics.

Maybe those stubs should be made generic by moving them into 
kernel/kcsan/ and building them for all 32 bit architectures.

Christophe

> ---
>   arch/powerpc/Kconfig | 1 +
>   1 file changed, 1 insertion(+)
> 
> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
> index b8c4ac56bddc..55bc2d724c73 100644
> --- a/arch/powerpc/Kconfig
> +++ b/arch/powerpc/Kconfig
> @@ -198,6 +198,7 @@ config PPC
>   	select HAVE_ARCH_KASAN			if PPC_RADIX_MMU
>   	select HAVE_ARCH_KASAN			if PPC_BOOK3E_64
>   	select HAVE_ARCH_KASAN_VMALLOC		if HAVE_ARCH_KASAN
> +	select HAVE_ARCH_KCSAN            if PPC64
>   	select HAVE_ARCH_KFENCE			if ARCH_SUPPORTS_DEBUG_PAGEALLOC
>   	select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
>   	select HAVE_ARCH_KGDB