[PATCH] i386: Implement alternative_io for i386

Ported from x86-64.
Signed-off-by: Andi Kleen <ak@suse.de>

include/asm-i386/alternative.h

@@ -82,6 +82,21 @@ static inline void alternatives_smp_switch(int smp) {}
 		      "663:\n\t" newinstr "\n664:\n"   /* replacement */\
 		      ".previous" :: "i" (feature), ##input)
 
+/* Like alternative_input, but with a single output argument */
+#define alternative_io(oldinstr, newinstr, feature, output, input...) \
+	asm volatile ("661:\n\t" oldinstr "\n662:\n"			\
+		      ".section .altinstructions,\"a\"\n"		\
+		      "  .align 4\n"					\
+		      "  .long 661b\n"            /* label */		\
+		      "  .long 663f\n"		  /* new instruction */	\
+		      "  .byte %c[feat]\n"        /* feature bit */	\
+		      "  .byte 662b-661b\n"       /* sourcelen */	\
+		      "  .byte 664f-663f\n"       /* replacementlen */	\
+		      ".previous\n"					\
+		      ".section .altinstr_replacement,\"ax\"\n"		\
+		      "663:\n\t" newinstr "\n664:\n"   /* replacement */ \
+		      ".previous" : output : [feat] "i" (feature), ##input)
+
 /*
  * Alternative inline assembly for SMP.
  *