From: Ralf Baechle <ralf@linux-mips.org>
Date: Thu, 22 Dec 2005 12:41:29 +0000 (+0100)
Subject: MIPS: R2: Try to bulletproof instruction_hazard against miss-compilation.
X-Git-Tag: v2.6.16-rc1~462^2~2
X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=7043ad4f4c81914ca9e2cd2208c8f4801ed63735;p=linux-block.git

MIPS: R2: Try to bulletproof instruction_hazard against miss-compilation.

Gcc has a tradition of misscompiling the previous construct using the
address of a label as argument to inline assembler.  Gas otoh has the
annoying difference between la and dla which are only usable for 32-bit
rsp. 64-bit code, so can't be used without conditional compilation.
The alterantive is switching the assembler to 64-bit code which happens
to work right even for 32-bit code ...

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
---

diff --git a/include/asm-mips/hazards.h b/include/asm-mips/hazards.h
index 7517189e469f..2fc90632f88c 100644
--- a/include/asm-mips/hazards.h
+++ b/include/asm-mips/hazards.h
@@ -233,15 +233,25 @@ __asm__(
 #endif
 
 #ifdef CONFIG_CPU_MIPSR2
+/*
+ * gcc has a tradition of misscompiling the previous construct using the
+ * address of a label as argument to inline assembler.  Gas otoh has the
+ * annoying difference between la and dla which are only usable for 32-bit
+ * rsp. 64-bit code, so can't be used without conditional compilation.
+ * The alterantive is switching the assembler to 64-bit code which happens
+ * to work right even for 32-bit code ...
+ */
 #define instruction_hazard()						\
 do {									\
-__label__ __next;							\
+	unsigned long tmp;						\
+									\
 	__asm__ __volatile__(						\
+	"	.set	mips64r2				\n"	\
+	"	dla	%0, 1f					\n"	\
 	"	jr.hb	%0					\n"	\
-	:								\
-	: "r" (&&__next));						\
-__next:									\
-	;								\
+	"	.set	mips0					\n"	\
+	"1:							\n"	\
+	: "=r" (tmp));							\
 } while (0)
 
 #else