From: Thomas Weißschuh Date: Thu, 21 Aug 2025 07:56:44 +0000 (+0200) Subject: arm64: uapi: Provide correct __BITS_PER_LONG for the compat vDSO X-Git-Tag: v6.17-rc5~11^2~2 X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=9a6d3ff10f7f538835cae4799562004ee46922c5;p=users%2Fgriffoul%2Flinux.git arm64: uapi: Provide correct __BITS_PER_LONG for the compat vDSO The generic vDSO library uses the UAPI headers. On arm64 __BITS_PER_LONG is always '64' even when used from the compat vDSO. In that case __GENMASK() does an illegal bitshift, invoking undefined behaviour. Change __BITS_PER_LONG to also work when used from the comapt vDSO. To not confuse real userspace, only do this when building the kernel. Reported-by: John Stultz Closes: https://lore.kernel.org/lkml/CANDhNCqvKOc9JgphQwr0eDyJiyG4oLFS9R8rSFvU0fpurrJFDg@mail.gmail.com/ Fixes: cd3557a7618b ("vdso/gettimeofday: Add support for auxiliary clocks") Signed-off-by: Thomas Weißschuh Acked-by: Arnd Bergmann Tested-by: John Stultz Link: https://lore.kernel.org/r/20250821-vdso-arm64-compat-bitsperlong-v1-1-700bcabe7732@linutronix.de Signed-off-by: Catalin Marinas --- diff --git a/arch/arm64/include/uapi/asm/bitsperlong.h b/arch/arm64/include/uapi/asm/bitsperlong.h index 485d60bee26c..d59730975f30 100644 --- a/arch/arm64/include/uapi/asm/bitsperlong.h +++ b/arch/arm64/include/uapi/asm/bitsperlong.h @@ -17,7 +17,12 @@ #ifndef __ASM_BITSPERLONG_H #define __ASM_BITSPERLONG_H +#if defined(__KERNEL__) && !defined(__aarch64__) +/* Used by the compat vDSO */ +#define __BITS_PER_LONG 32 +#else #define __BITS_PER_LONG 64 +#endif #include