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

tip-bot2 for Thomas Gleixner
2020-05-19T20:01:04Z

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@linutronix.de>
AuthorDate: Tue, 12 May 2020 14:54:14 +02:00
Committer: Thomas Gleixner <tglx@linutronix.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@linutronix.de>
Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Acked-by: Juergen Gross <jgross@suse.com>
Acked-by: Peter Zijlstra <peterz@infradead.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