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Commit a5122106 authored by Andy Lutomirski's avatar Andy Lutomirski Committed by Ingo Molnar
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x86/entry/64: Merge the fast and slow SYSRET paths 



They did almost the same thing.  Remove a bunch of pointless
instructions (mostly hidden in macros) and reduce cognitive load by
merging them.

Signed-off-by: default avatarAndy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bpetkov@suse.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1204e20233fcab9130a1ba80b3b1879b5db3fc1f.1509609304.git.luto@kernel.org


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 4fbb3910

arch/x86/entry/entry_64.S

+3 −3
Original line number Original line Diff line number Diff line
@@ -220,10 +220,9 @@ entry_SYSCALL_64_fastpath: 
	TRACE_IRQS_ON		/* user mode is traced as IRQs on */

	TRACE_IRQS_ON		/* user mode is traced as IRQs on */

	movq	RIP(%rsp), %rcx

	movq	RIP(%rsp), %rcx

	movq	EFLAGS(%rsp), %r11

	movq	EFLAGS(%rsp), %r11

	RESTORE_C_REGS_EXCEPT_RCX_R11

	addq	$6*8, %rsp	/* skip extra regs -- they were preserved */

	movq	RSP(%rsp), %rsp

	UNWIND_HINT_EMPTY

	UNWIND_HINT_EMPTY

	USERGS_SYSRET64

	jmp	.Lpop_c_regs_except_rcx_r11_and_sysret





1:

1:

	/*

	/*
@@ -317,6 +316,7 @@ syscall_return_via_sysret: 
	/* rcx and r11 are already restored (see code above) */

	/* rcx and r11 are already restored (see code above) */

	UNWIND_HINT_EMPTY

	UNWIND_HINT_EMPTY

	POP_EXTRA_REGS

	POP_EXTRA_REGS

.Lpop_c_regs_except_rcx_r11_and_sysret:

	popq	%rsi	/* skip r11 */

	popq	%rsi	/* skip r11 */

	popq	%r10

	popq	%r10

	popq	%r9

	popq	%r9