linux-kernel - [tip: x86/entry] x86/entry/64: Use native swapgs in asm_load_gs

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Message-ID: <158991831915.17951.5043866712580848379.tip-bot2@tip-bot2>
Date:   Tue, 19 May 2020 19:58:39 -0000
From:   "tip-bot2 for Thomas Gleixner" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        "Steven Rostedt (VMware)" <rostedt@...dmis.org>,
        Juergen Gross <jgross@...e.com>,
        Peter Zijlstra <peterz@...radead.org>, x86 <x86@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: [tip: x86/entry] x86/entry/64: Use native swapgs in asm_load_gs_index()

The following commit has been merged into the x86/entry branch of tip:

Commit-ID:     3d1723d88a0c28ad7db441aed6c912e99467abfe
Gitweb:        https://git.kernel.org/tip/3d1723d88a0c28ad7db441aed6c912e99467abfe
Author:        Thomas Gleixner <tglx@...utronix.de>
AuthorDate:    Tue, 12 May 2020 14:54:14 +02:00
Committer:     Thomas Gleixner <tglx@...utronix.de>
CommitterDate: Tue, 19 May 2020 16:03:54 +02:00

x86/entry/64: Use native swapgs in asm_load_gs_index()

When PARAVIRT_XXL is in use, then load_gs_index() uses xen_load_gs_index()
and asm_load_gs_index() is unused.

It's therefore pointless to use the paravirtualized SWAPGS implementation
in asm_load_gs_index(). Switch it to a plain swapgs.

Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Reviewed-by: Steven Rostedt (VMware) <rostedt@...dmis.org>
Acked-by: Juergen Gross <jgross@...e.com>
Acked-by: Peter Zijlstra <peterz@...radead.org>
Link: https://lkml.kernel.org/r/20200512213809.583980272@linutronix.de

---
 arch/x86/entry/entry_64.S | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index be8ed3a..9747b42 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -1043,11 +1043,11 @@ idtentry simd_coprocessor_error		do_simd_coprocessor_error	has_error_code=0
  */
 SYM_FUNC_START(asm_load_gs_index)
 	FRAME_BEGIN
-	SWAPGS
+	swapgs
 .Lgs_change:
 	movl	%edi, %gs
 2:	ALTERNATIVE "", "mfence", X86_BUG_SWAPGS_FENCE
-	SWAPGS
+	swapgs
 	FRAME_END
 	ret
 SYM_FUNC_END(asm_load_gs_index)
@@ -1057,7 +1057,7 @@ EXPORT_SYMBOL(asm_load_gs_index)
 	.section .fixup, "ax"
 	/* running with kernelgs */
 SYM_CODE_START_LOCAL_NOALIGN(.Lbad_gs)
-	SWAPGS					/* switch back to user gs */
+	swapgs					/* switch back to user gs */
 .macro ZAP_GS
 	/* This can't be a string because the preprocessor needs to see it. */
 	movl $__USER_DS, %eax