x86/entry_64: Remove .fixup usage

Place the anonymous .fixup code at the tail of the regular functions.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com>
Reviewed-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Lai Jiangshan <jiangshanlai@gmail.com>
Link: https://lore.kernel.org/r/20211110101325.186049322@infradead.org

Author: Peter Zijlstra

arch/x86/entry/entry_64.S

@@ -739,13 +739,9 @@ SYM_FUNC_START(asm_load_gs_index)
 	swapgs
 	FRAME_END
 	RET
-SYM_FUNC_END(asm_load_gs_index)
-EXPORT_SYMBOL(asm_load_gs_index)
 
-	_ASM_EXTABLE(.Lgs_change, .Lbad_gs)
-	.section .fixup, "ax"
 	/* running with kernelgs */
-SYM_CODE_START_LOCAL_NOALIGN(.Lbad_gs)
+.Lbad_gs:
 	swapgs					/* switch back to user gs */
 .macro ZAP_GS
 	/* This can't be a string because the preprocessor needs to see it. */
@@ -756,8 +752,11 @@ SYM_CODE_START_LOCAL_NOALIGN(.Lbad_gs)
 	xorl	%eax, %eax
 	movl	%eax, %gs
 	jmp	2b
-SYM_CODE_END(.Lbad_gs)
-	.previous
+
+	_ASM_EXTABLE(.Lgs_change, .Lbad_gs)
+
+SYM_FUNC_END(asm_load_gs_index)
+EXPORT_SYMBOL(asm_load_gs_index)
 
 #ifdef CONFIG_XEN_PV
 /*