| From | Thomas Gleixner <> | Subject | [patch 12/38] x86/entry: Make sync_regs() invocation a tail call | Date | Sun, 17 Jul 2022 01:17:29 +0200 (CEST) |
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From: Peter Zijlstra <peterz@infradead.org>
No point in having a call there. Spare the call/ret overhead.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> --- arch/x86/entry/entry_64.S | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-)
--- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -1060,11 +1060,8 @@ SYM_CODE_START_LOCAL(error_entry) UNTRAIN_RET leaq 8(%rsp), %rdi /* arg0 = pt_regs pointer */ -.Lerror_entry_from_usermode_after_swapgs: - /* Put us onto the real thread stack. */ - call sync_regs - RET + jmp sync_regs /* * There are two places in the kernel that can potentially fault with @@ -1122,7 +1119,7 @@ SYM_CODE_START_LOCAL(error_entry) leaq 8(%rsp), %rdi /* arg0 = pt_regs pointer */ call fixup_bad_iret mov %rax, %rdi - jmp .Lerror_entry_from_usermode_after_swapgs + jmp sync_regs SYM_CODE_END(error_entry) SYM_CODE_START_LOCAL(error_return)
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