From: Antony Yu <swpenim@gmail.com>
To: unlisted-recipients:; (no To-header on input)
Cc: swpenim@gmail.com, Russell King <linux@armlinux.org.uk>,
Nathan Chancellor <natechancellor@gmail.com>,
Nick Desaulniers <ndesaulniers@google.com>,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com
Subject: [RESEND,PATCH] ARM: fix __div64_32() error when compiling with clang
Date: Mon, 23 Nov 2020 15:36:32 +0800 [thread overview]
Message-ID: <20201123073634.6854-1-swpenim@gmail.com> (raw)
__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@gmail.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
WARNING: multiple messages have this Message-ID (diff)
From: Antony Yu <swpenim@gmail.com>
Cc: swpenim@gmail.com, Nick Desaulniers <ndesaulniers@google.com>,
Russell King <linux@armlinux.org.uk>,
linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com,
Nathan Chancellor <natechancellor@gmail.com>,
linux-arm-kernel@lists.infradead.org
Subject: [RESEND,PATCH] ARM: fix __div64_32() error when compiling with clang
Date: Mon, 23 Nov 2020 15:36:32 +0800 [thread overview]
Message-ID: <20201123073634.6854-1-swpenim@gmail.com> (raw)
__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@gmail.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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next reply other threads:[~2020-11-23 7:38 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-23 7:36 Antony Yu [this message]
2020-11-23 7:36 ` [RESEND,PATCH] ARM: fix __div64_32() error when compiling with clang Antony Yu
2020-11-23 18:16 ` Nathan Chancellor
2020-11-23 18:16 ` Nathan Chancellor
2020-11-24 7:42 ` Antony Yu
2020-11-24 10:14 ` Antony Yu
2020-11-24 10:14 ` [RESEND, PATCH] " Antony Yu
2020-11-24 21:06 ` [RESEND,PATCH] " Nick Desaulniers
2020-11-24 21:06 ` [RESEND, PATCH] " Nick Desaulniers
2020-11-30 8:20 ` [PATCH v2] " Antony Yu
2020-11-30 8:20 ` Antony Yu
2020-11-24 23:16 ` [RESEND,PATCH] " kernel test robot
2020-11-24 23:16 ` [RESEND, PATCH] " kernel test robot
2020-11-24 23:16 ` [RESEND,PATCH] " kernel test robot
2020-11-30 10:11 ` Ard Biesheuvel
2020-11-30 10:11 ` [RESEND, PATCH] " Ard Biesheuvel
2020-11-30 10:12 ` [RESEND,PATCH] " Ard Biesheuvel
2020-11-30 10:12 ` [RESEND, PATCH] " Ard Biesheuvel
2020-11-30 10:21 ` [RESEND,PATCH] " Russell King - ARM Linux admin
2020-11-30 10:21 ` Russell King - ARM Linux admin
2020-11-30 10:40 ` Ard Biesheuvel
2020-11-30 10:40 ` [RESEND, PATCH] " Ard Biesheuvel
2020-11-30 13:58 ` [RESEND,PATCH] " David Laight
2020-11-30 13:58 ` David Laight
2020-11-30 14:18 ` Russell King - ARM Linux admin
2020-11-30 14:18 ` Russell King - ARM Linux admin
2020-11-30 15:50 ` Nicolas Pitre
2020-11-30 15:50 ` Nicolas Pitre
2020-11-30 17:18 ` Ard Biesheuvel
2020-11-30 17:18 ` [RESEND, PATCH] " Ard Biesheuvel
2020-11-30 17:52 ` [RESEND,PATCH] " Nicolas Pitre
2020-11-30 17:52 ` Nicolas Pitre
2020-11-30 18:08 ` Ard Biesheuvel
2020-11-30 18:08 ` [RESEND, PATCH] " Ard Biesheuvel
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