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Date: Mon, 23 Nov 2020 15:36:32 +0800 From: Antony Yu <swpenim@...il.com> To: unlisted-recipients:; (no To-header on input) Cc: swpenim@...il.com, Russell King <linux@...linux.org.uk>, Nathan Chancellor <natechancellor@...il.com>, Nick Desaulniers <ndesaulniers@...gle.com>, linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org, clang-built-linux@...glegroups.com Subject: [RESEND,PATCH] 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 <swpenim@...il.com> --- 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..809efc51e90f 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" (__n) : "r" (__n), "r" (__base) : "ip", "lr", "cc"); *n = __res; -- 2.23.0
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