6.12-stable review patch. If anyone has any objections, please let me know.
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From: Liyuan Pang pangliyuan1@huawei.com
[ Upstream commit edb924a7211c9aa7a4a415e03caee4d875e46b8e ]
In the inline assembly inside load_unaligned_zeropad(), the "addr" is constrained as input-only operand. The compiler assumes that on exit from the asm statement these operands contain the same values as they had before executing the statement, but when kernel page fault happened, the assembly fixup code "bic %2 %2, #0x3" modify the value of "addr", which may lead to an unexpected behavior.
Use a temporary variable "tmp" to handle it, instead of modifying the input-only operand, just like what arm64's load_unaligned_zeropad() does.
Fixes: b9a50f74905a ("ARM: 7450/1: dcache: select DCACHE_WORD_ACCESS for little-endian ARMv6+ CPUs") Co-developed-by: Xie Yuanbin xieyuanbin1@huawei.com Signed-off-by: Xie Yuanbin xieyuanbin1@huawei.com Signed-off-by: Liyuan Pang pangliyuan1@huawei.com Signed-off-by: Russell King (Oracle) rmk+kernel@armlinux.org.uk Signed-off-by: Sasha Levin sashal@kernel.org --- arch/arm/include/asm/word-at-a-time.h | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/arch/arm/include/asm/word-at-a-time.h b/arch/arm/include/asm/word-at-a-time.h index f9a3897b06e7f..5023f98d8293d 100644 --- a/arch/arm/include/asm/word-at-a-time.h +++ b/arch/arm/include/asm/word-at-a-time.h @@ -67,7 +67,7 @@ static inline unsigned long find_zero(unsigned long mask) */ static inline unsigned long load_unaligned_zeropad(const void *addr) { - unsigned long ret, offset; + unsigned long ret, tmp;
/* Load word from unaligned pointer addr */ asm( @@ -75,9 +75,9 @@ static inline unsigned long load_unaligned_zeropad(const void *addr) "2:\n" " .pushsection .text.fixup,"ax"\n" " .align 2\n" - "3: and %1, %2, #0x3\n" - " bic %2, %2, #0x3\n" - " ldr %0, [%2]\n" + "3: bic %1, %2, #0x3\n" + " ldr %0, [%1]\n" + " and %1, %2, #0x3\n" " lsl %1, %1, #0x3\n" #ifndef __ARMEB__ " lsr %0, %0, %1\n" @@ -90,7 +90,7 @@ static inline unsigned long load_unaligned_zeropad(const void *addr) " .align 3\n" " .long 1b, 3b\n" " .popsection" - : "=&r" (ret), "=&r" (offset) + : "=&r" (ret), "=&r" (tmp) : "r" (addr), "Qo" (*(unsigned long *)addr));
return ret;