linux-kernel - [PATCH v3 7/7] x86/entry: Make gs

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Date:	Thu,  7 Apr 2016 17:31:50 -0700
From:	Andy Lutomirski <luto@...nel.org>
To:	Borislav Petkov <bp@...en8.de>, security@...nel.org,
	x86@...nel.org, linux-kernel@...r.kernel.org
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Rudolf Marek <r.marek@...embler.cz>,
	Borislav Petkov <bp@...e.de>, Andy Lutomirski <luto@...nel.org>
Subject: [PATCH v3 7/7] x86/entry: Make gs_change a local label

From: Borislav Petkov <bp@...e.de>

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

Signed-off-by: Borislav Petkov <bp@...e.de>
Signed-off-by: Andy Lutomirski <luto@...nel.org>
---
 arch/x86/entry/entry_64.S | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 64d2033d1e49..1693c17dbf81 100644
--- a/arch/x86/entry/entry_64.S
+++ b/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
 
-- 
2.5.5