x86/entry/64: Make gs_change a local label

... so that it doesn't appear in objdump output.

Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rudolf Marek <r.marek@assembler.cz>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/b9c532a0e5f8d56dede2bd59767d40024d5a75e2.1460075211.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/entry/entry_64.S

@@ -781,7 +781,7 @@ ENTRY(native_load_gs_index)
 	pushfq
 	DISABLE_INTERRUPTS(CLBR_ANY & ~CLBR_RDI)
 	SWAPGS
-gs_change:
+.Lgs_change:
 	movl	%edi, %gs
 2:	ALTERNATIVE "", "mfence", X86_BUG_SWAPGS_FENCE
 	SWAPGS
@@ -789,7 +789,7 @@ gs_change:
 	ret
 END(native_load_gs_index)
 
-	_ASM_EXTABLE(gs_change, bad_gs)
+	_ASM_EXTABLE(.Lgs_change, bad_gs)
 	.section .fixup, "ax"
 	/* running with kernelgs */
 bad_gs:
@@ -1019,13 +1019,13 @@ ENTRY(error_entry)
 	movl	%ecx, %eax			/* zero extend */
 	cmpq	%rax, RIP+8(%rsp)
 	je	.Lbstep_iret
-	cmpq	$gs_change, RIP+8(%rsp)
+	cmpq	$.Lgs_change, RIP+8(%rsp)
 	jne	.Lerror_entry_done
 
 	/*
-	 * hack: gs_change can fail with user gsbase.  If this happens, fix up
+	 * hack: .Lgs_change can fail with user gsbase.  If this happens, fix up
 	 * gsbase and proceed.  We'll fix up the exception and land in
-	 * gs_change's error handler with kernel gsbase.
+	 * .Lgs_change's error handler with kernel gsbase.
 	 */
 	jmp	.Lerror_entry_from_usermode_swapgs