linux-kernel - [PATCH V6 13/49] x86/entry: Expose the address of .Lgs

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Message-Id: <20211126101209.8613-14-jiangshanlai@gmail.com>
Date:   Fri, 26 Nov 2021 18:11:33 +0800
From:   Lai Jiangshan <jiangshanlai@...il.com>
To:     linux-kernel@...r.kernel.org
Cc:     x86@...nel.org, Lai Jiangshan <laijs@...ux.alibaba.com>,
        Andy Lutomirski <luto@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "H. Peter Anvin" <hpa@...or.com>
Subject: [PATCH V6 13/49] x86/entry: Expose the address of .Lgs_change to entry64.c

From: Lai Jiangshan <laijs@...ux.alibaba.com>

The address of .Lgs_change will be used in traps.c in later patch when
some entry code is implemented in entry64.c.  So the address of .Lgs_change
is exposed to traps.c for preparation.

Signed-off-by: Lai Jiangshan <laijs@...ux.alibaba.com>
---
 arch/x86/entry/entry64.c  | 2 ++
 arch/x86/entry/entry_64.S | 6 +++---
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/arch/x86/entry/entry64.c b/arch/x86/entry/entry64.c
index 762595603ce7..9813a30dbadb 100644
--- a/arch/x86/entry/entry64.c
+++ b/arch/x86/entry/entry64.c
@@ -12,3 +12,5 @@
  * is PTI user CR3 or both.
  */
 #include <asm/traps.h>
+
+extern unsigned char asm_load_gs_index_gs_change[];
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 44774cc5bcc9..5db0196835cd 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -733,7 +733,7 @@ _ASM_NOKPROBE(common_interrupt_return)
 SYM_FUNC_START(asm_load_gs_index)
 	FRAME_BEGIN
 	swapgs
-.Lgs_change:
+SYM_INNER_LABEL(asm_load_gs_index_gs_change, SYM_L_GLOBAL)
 	movl	%edi, %gs
 2:	ALTERNATIVE "", "mfence", X86_BUG_SWAPGS_FENCE
 	swapgs
@@ -742,7 +742,7 @@ SYM_FUNC_START(asm_load_gs_index)
 SYM_FUNC_END(asm_load_gs_index)
 EXPORT_SYMBOL(asm_load_gs_index)
 
-	_ASM_EXTABLE(.Lgs_change, .Lbad_gs)
+	_ASM_EXTABLE(asm_load_gs_index_gs_change, .Lbad_gs)
 	.section .fixup, "ax"
 	/* running with kernelgs */
 SYM_CODE_START_LOCAL_NOALIGN(.Lbad_gs)
@@ -1008,7 +1008,7 @@ SYM_CODE_START_LOCAL(error_entry)
 	movl	%ecx, %eax			/* zero extend */
 	cmpq	%rax, RIP+8(%rsp)
 	je	.Lbstep_iret
-	cmpq	$.Lgs_change, RIP+8(%rsp)
+	cmpq	$asm_load_gs_index_gs_change, RIP+8(%rsp)
 	jne	.Lerror_entry_done_lfence
 
 	/*
-- 
2.19.1.6.gb485710b