x86/entry/64: Use native swapgs in asm_load_gs_index() (c9317202) · Commits · 戴 / test

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

+3 −3

Original line number	Diff line number	Diff line
		@@ -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

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