diff options
| author | Mark Rutland <mark.rutland@arm.com> | 2026-09-08 16:17:21 +0100 |
|---|---|---|
| committer | Will Deacon <will@kernel.org> | 2026-09-11 12:32:22 +0000 |
| commit | 885bff055a0f251a51a0d4fd4f0a7b525582a3de (patch) | |
| tree | a71b5e72551644e57d33dddeb7bc6e4e41ef35b0 /arch/arm64/include/asm | |
| parent | e4a6f57d22e079e23fafac51057fad534160b269 (diff) | |
arm64: percpu: Fix this_cpu_write() casting
The arm64 implementation of this_cpu_write() casts 'val' to unsigned
long. This is necessary to handle cases where 'val' is a pointer type,
and to avoid spurious compiler warnings for the (unreachable!) cases
where the pointer type would be cast to a smaller integer type.
Unfortunately, the cast is applied to 'val' rather than '(val)', which
won't always generate the expected value when 'val' is an expression.
For example, for this_cpu_write(pcp, zero - 1), where 'pcp' is a u64 and
'zero' is a u32:
* 'zero' ===> (u32) 0x00000000
* 'zero - 1' ===> (u32) 0xffffffff
* '(unsigned long)zero - 1' ===> (u64) 0xffffffffffffffff
* '(unsigned long)(zero - 1)' ===> (u64) 0x00000000ffffffff
Fix this by adding brackets around 'val'.
Fixes: 959bf2fd03b5 ("arm64: percpu: Rewrite per-cpu ops to allow use of LSE atomics")
Reported-by: David Laight <david.laight.linux@gmail.com>
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: David Laight <david.laight.linux@gmail.com>
Reviewed-by: Jinjie Ruan <ruanjinjie@huawei.com>
Tested-by: Muhammad Usama Anjum <usama.anjum@arm.com>
Acked-by: Christopher Lameter (Ampere) <cl@gentwo.org>
Cc: Ada Couprie Diaz <ada.coupriediaz@arm.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Vladimir Murzin <vladimir.murzin@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Yang Shi <yang@os.amperecomputing.com>
Cc: stable@vger.kernel.org
Reviewed-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Signed-off-by: Will Deacon <will@kernel.org>
Diffstat (limited to 'arch/arm64/include/asm')
| -rw-r--r-- | arch/arm64/include/asm/percpu.h | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/arch/arm64/include/asm/percpu.h b/arch/arm64/include/asm/percpu.h index b57b2bb00967..63bbfd4944a3 100644 --- a/arch/arm64/include/asm/percpu.h +++ b/arch/arm64/include/asm/percpu.h @@ -179,13 +179,13 @@ PERCPU_RET_OP(add, add, ldadd) _pcp_protect_return(__percpu_read_64, pcp) #define this_cpu_write_1(pcp, val) \ - _pcp_protect(__percpu_write_8, pcp, (unsigned long)val) + _pcp_protect(__percpu_write_8, pcp, (unsigned long)(val)) #define this_cpu_write_2(pcp, val) \ - _pcp_protect(__percpu_write_16, pcp, (unsigned long)val) + _pcp_protect(__percpu_write_16, pcp, (unsigned long)(val)) #define this_cpu_write_4(pcp, val) \ - _pcp_protect(__percpu_write_32, pcp, (unsigned long)val) + _pcp_protect(__percpu_write_32, pcp, (unsigned long)(val)) #define this_cpu_write_8(pcp, val) \ - _pcp_protect(__percpu_write_64, pcp, (unsigned long)val) + _pcp_protect(__percpu_write_64, pcp, (unsigned long)(val)) #define this_cpu_add_1(pcp, val) \ _pcp_protect(__percpu_add_case_8, pcp, val) |