MIPS: Unify sc beqz definition

We currently duplicate the definition of __scbeqz in asm/atomic.h &
asm/cmpxchg.h. Move it to asm/llsc.h & rename it to __SC_BEQZ to fit
better with the existing __SC macro provided there.

We include a tab in the string in order to avoid the need for users to
indent code any further to include whitespace of their own after the
instruction mnemonic.

Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: linux-mips@vger.kernel.org
Cc: Huacai Chen <chenhc@lemote.com>
Cc: Jiaxun Yang <jiaxun.yang@flygoat.com>
Cc: linux-kernel@vger.kernel.org

arch/mips/include/asm/llsc.h

@@ -25,4 +25,15 @@
 #define __EXT		"dext	"
 #endif
 
+/*
+ * Using a branch-likely instruction to check the result of an sc instruction
+ * works around a bug present in R10000 CPUs prior to revision 3.0 that could
+ * cause ll-sc sequences to execute non-atomically.
+ */
+#if R10000_LLSC_WAR
+# define __SC_BEQZ "beqzl	"
+#else
+# define __SC_BEQZ "beqz	"
+#endif
+
 #endif /* __ASM_LLSC_H  */