x86, extable: Use .pushsection ... .popsection for _ASM_EXTABLE()

Instead of using .section ... .previous, use .pushsection
... .popsection; this is (hopefully) a bit more robust, especially in
complex assembly code.
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Cc: David Daney <david.daney@cavium.com>
Link: http://lkml.kernel.org/r/CA%2B55aFyijf43qSu3N9nWHEBwaGbb7T2Oq9A=9EyR=Jtyqfq_cQ@mail.gmail.com

arch/x86/include/asm/asm.h

@@ -42,17 +42,17 @@
 
 /* Exception table entry */
 #ifdef __ASSEMBLY__
-# define _ASM_EXTABLE(from,to)	    \
-	__ASM_EX_SEC ;		    \
-	_ASM_ALIGN ;		    \
-	_ASM_PTR from , to ;	    \
-	.previous
+# define _ASM_EXTABLE(from,to)			\
+	.pushsection "__ex_table","a" ;		\
+	_ASM_ALIGN ;				\
+	_ASM_PTR from , to ;			\
+	.popsection
 #else
-# define _ASM_EXTABLE(from,to) \
-	__ASM_EX_SEC	\
-	_ASM_ALIGN "\n" \
-	_ASM_PTR #from "," #to "\n" \
-	" .previous\n"
+# define _ASM_EXTABLE(from,to)			\
+	" .pushsection \"__ex_table\",\"a\"\n"	\
+	_ASM_ALIGN "\n" 			\
+	_ASM_PTR #from "," #to "\n" 		\
+	" .popsection\n"
 #endif
 
 #endif /* _ASM_X86_ASM_H */