Re: [PATCH v3 05/23] arm64: Share system register related headers and functions with s390

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential
issue to consider:
- [High] arm64: cache.h: -Wundef build failure in vdso32 on
  ARM64_S390_COMMON
--

commit fc7c54ef2eb921844dfa6922455b5c6e7c8095c4
Author: Steffen Eiden <seiden@linux.ibm.com>

arm64: Share system register related headers and functions with s390

This commit marks arm64 system register, CPU identification, exception
emulation, and mitigation definitions as shared with s390.

> diff --git a/arch/arm64/include/asm/cache.h b/arch/arm64/include/asm/cache.h
> index 10a7ffadee3da..ee3078c687687 100644
> --- a/arch/arm64/include/asm/cache.h
> +++ b/arch/arm64/include/asm/cache.h
> @@ -8,6 +8,7 @@
>  #define L1_CACHE_SHIFT		(6)
>  #define L1_CACHE_BYTES		(1 << L1_CACHE_SHIFT)
>  
> +#if ARM64_S390_COMMON == 1
>  #define CLIDR_LOUU_SHIFT	27
>  #define CLIDR_LOC_SHIFT		24
>  #define CLIDR_LOUIS_SHIFT	21
> @@ -25,6 +26,8 @@
>  /* Ttypen, bits [2(n - 1) + 34 : 2(n - 1) + 33], for n = 1 to 7 */
>  #define CLIDR_TTYPE_SHIFT(level)	(2 * ((level) - 1) + CLIDR_EL1_Ttypen_SHIFT)
>  
> +#endif /* ARM64_S390_COMMON == 1 */

[Severity: High]
Does evaluating ARM64_S390_COMMON outside the !defined(BUILD_VDSO) guard
break the 32-bit compat vDSO build with -Wundef?

arch/arm64/kernel/vdso32/Makefile sets VDSO_CPPFLAGS from scratch without
inheriting KBUILD_CPPFLAGS (where -DARM64_S390_COMMON=1 is defined) while
enabling -Wundef in VDSO_CFLAGS.  When arch/arm64/kernel/vdso32/vgettimeofday.c
includes asm/cache.h via vdso/datapage.h -> vdso/cache.h, ARM64_S390_COMMON
is undefined, causing a -Wundef warning and a build regression when
CONFIG_COMPAT_VDSO=y and CONFIG_WERROR=y.

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261106-sysreg-v3-0-75e95980fb10@linux.ibm.com?part=5