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authorKees Cook <keescook@chromium.org>2022-01-12 12:22:59 -0800
committerCatalin Marinas <catalin.marinas@arm.com>2022-01-20 09:13:48 +0000
commit3364c6ce23c6e347c63fc895e0d6d1e8a9407849 (patch)
tree913d3bc6c1fc6de38e830453309bf637b1b1a4cd /arch
parent440323b6cf5b9896013a78c4f578823e8243a7fd (diff)
arm64: atomics: lse: Dereference matching size
When building with -Warray-bounds, the following warning is generated: In file included from ./arch/arm64/include/asm/lse.h:16, from ./arch/arm64/include/asm/cmpxchg.h:14, from ./arch/arm64/include/asm/atomic.h:16, from ./include/linux/atomic.h:7, from ./include/asm-generic/bitops/atomic.h:5, from ./arch/arm64/include/asm/bitops.h:25, from ./include/linux/bitops.h:33, from ./include/linux/kernel.h:22, from kernel/printk/printk.c:22: ./arch/arm64/include/asm/atomic_lse.h:247:9: warning: array subscript 'long unsigned int[0]' is partly outside array bounds of 'atomic_t[1]' [-Warray-bounds] 247 | asm volatile( \ | ^~~ ./arch/arm64/include/asm/atomic_lse.h:266:1: note: in expansion of macro '__CMPXCHG_CASE' 266 | __CMPXCHG_CASE(w, , acq_, 32, a, "memory") | ^~~~~~~~~~~~~~ kernel/printk/printk.c:3606:17: note: while referencing 'printk_cpulock_owner' 3606 | static atomic_t printk_cpulock_owner = ATOMIC_INIT(-1); | ^~~~~~~~~~~~~~~~~~~~ This is due to the compiler seeing an unsigned long * cast against something (atomic_t) that is int sized. Replace the cast with the matching size cast. This results in no change in binary output. Note that __ll_sc__cmpxchg_case_##name##sz already uses the same constraint: [v] "+Q" (*(u##sz *)ptr Which is why only the LSE form needs updating and not the LL/SC form, so this change is unlikely to be problematic. Cc: Will Deacon <will@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: linux-arm-kernel@lists.infradead.org Acked-by: Ard Biesheuvel <ardb@kernel.org> Acked-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Kees Cook <keescook@chromium.org> Link: https://lore.kernel.org/r/20220112202259.3950286-1-keescook@chromium.org Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch')
-rw-r--r--arch/arm64/include/asm/atomic_lse.h2
-rw-r--r--arch/arm64/include/asm/cmpxchg.h2
2 files changed, 2 insertions, 2 deletions
diff --git a/arch/arm64/include/asm/atomic_lse.h b/arch/arm64/include/asm/atomic_lse.h
index d955ade5df7c..5d460f6b7675 100644
--- a/arch/arm64/include/asm/atomic_lse.h
+++ b/arch/arm64/include/asm/atomic_lse.h
@@ -249,7 +249,7 @@ __lse__cmpxchg_case_##name##sz(volatile void *ptr, \
" mov %" #w "[tmp], %" #w "[old]\n" \
" cas" #mb #sfx "\t%" #w "[tmp], %" #w "[new], %[v]\n" \
" mov %" #w "[ret], %" #w "[tmp]" \
- : [ret] "+r" (x0), [v] "+Q" (*(unsigned long *)ptr), \
+ : [ret] "+r" (x0), [v] "+Q" (*(u##sz *)ptr), \
[tmp] "=&r" (tmp) \
: [old] "r" (x1), [new] "r" (x2) \
: cl); \
diff --git a/arch/arm64/include/asm/cmpxchg.h b/arch/arm64/include/asm/cmpxchg.h
index f9bef42c1411..497acf134d99 100644
--- a/arch/arm64/include/asm/cmpxchg.h
+++ b/arch/arm64/include/asm/cmpxchg.h
@@ -243,7 +243,7 @@ static inline void __cmpwait_case_##sz(volatile void *ptr, \
" cbnz %" #w "[tmp], 1f\n" \
" wfe\n" \
"1:" \
- : [tmp] "=&r" (tmp), [v] "+Q" (*(unsigned long *)ptr) \
+ : [tmp] "=&r" (tmp), [v] "+Q" (*(u##sz *)ptr) \
: [val] "r" (val)); \
}