Messages in this thread | | | Date | Fri, 18 Mar 2022 19:11:39 +0000 | Subject | Re: [PATCH] arm64: fix clang warning about TRAMP_VALIAS | From | Robin Murphy <> |
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On 2022-03-16 18:38, Arnd Bergmann wrote: > From: Arnd Bergmann <arnd@arndb.de> > > The newly introduced TRAMP_VALIAS definition causes a build warning > with clang-14: > > arch/arm64/include/asm/vectors.h:66:31: error: arithmetic on a null pointer treated as a cast from integer to pointer is a GNU extension [-Werror,-Wnull-pointer-arithmetic]
Tangentially, all the other GNU extensions we depend on throughout Linux are also GNU extensions. Do we know what's special about this one?
Robin.
> return (char *)TRAMP_VALIAS + SZ_2K * slot; > > Change the addition to something clang does not complain about. > > Fixes: bd09128d16fa ("arm64: Add percpu vectors for EL1") > Signed-off-by: Arnd Bergmann <arnd@arndb.de> > --- > arch/arm64/include/asm/vectors.h | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > I see this warning on 5.17-rc8, but did not test it on linux-next, > which may already have a fix. > > diff --git a/arch/arm64/include/asm/vectors.h b/arch/arm64/include/asm/vectors.h > index f64613a96d53..bc9a2145f419 100644 > --- a/arch/arm64/include/asm/vectors.h > +++ b/arch/arm64/include/asm/vectors.h > @@ -56,14 +56,14 @@ enum arm64_bp_harden_el1_vectors { > DECLARE_PER_CPU_READ_MOSTLY(const char *, this_cpu_vector); > > #ifndef CONFIG_UNMAP_KERNEL_AT_EL0 > -#define TRAMP_VALIAS 0 > +#define TRAMP_VALIAS 0ul > #endif > > static inline const char * > arm64_get_bp_hardening_vector(enum arm64_bp_harden_el1_vectors slot) > { > if (arm64_kernel_unmapped_at_el0()) > - return (char *)TRAMP_VALIAS + SZ_2K * slot; > + return (char *)(TRAMP_VALIAS + SZ_2K * slot); > > WARN_ON_ONCE(slot == EL1_VECTOR_KPTI); >
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