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x86/entry/64: Merge the fast and slow SYSRET paths

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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: Andy 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: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Andy Lutomirski 2017-11-02 00:59:04 -07:00 committed by Ingo Molnar
parent 4fbb39108f
commit a512210643
1 changed files with 3 additions and 3 deletions
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6
arch/x86/entry/entry_64.S
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@ -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