github-mirror/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-09-24 06:24:02 +02:00
Code Issues Actions Packages Projects Releases Wiki Activity Graph

arm64: percpu: Fix this_cpu_write() casting

Browse Source 
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: 959bf2fd03 ("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>
This commit is contained in:
Mark Rutland 2026-09-08 16:17:21 +01:00 committed by Will Deacon
parent e4a6f57d22
commit 885bff055a
1 changed files with 4 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
arch/arm64/include/asm/percpu.h
View File

@ -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)