>From 3a4c19e09079324a625941ea3c16fe4b0df2ed86 Mon Sep 17 00:00:00 2001 From: Antony Yu <[email protected]> Date: Mon, 9 Nov 2020 17:31:52 +0800 Subject: [PATCH v2] ARM: fix __div64_32() error when compiling with clang
__do_div64 clobbers the input register r0 in little endian system. According to the inline assembly document, if an input operand is modified, it should be tied to a output operand. This patch can prevent compilers from reusing r0 register after asm statements. Signed-off-by: Antony Yu <[email protected]> Reported-by: kernel test robot <[email protected]> --- changed in v2 - add kernel-test-robot tag - fix build failure on big endian arch/arm/include/asm/div64.h | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/arch/arm/include/asm/div64.h b/arch/arm/include/asm/div64.h index 898e9c78a7e7..961a129eb41f 100644 --- a/arch/arm/include/asm/div64.h +++ b/arch/arm/include/asm/div64.h @@ -39,9 +39,10 @@ static inline uint32_t __div64_32(uint64_t *n, uint32_t base) asm( __asmeq("%0", __xh) __asmeq("%1", "r2") __asmeq("%2", "r0") - __asmeq("%3", "r4") + __asmeq("%3", "r0") + __asmeq("%4", "r4") "bl __do_div64" - : "=r" (__rem), "=r" (__res) + : "=r" (__rem), "=r" (__res), "=r" (__xl) : "r" (__n), "r" (__base) : "ip", "lr", "cc"); *n = __res; -- 2.29.0
