From ef79ed20e3ae9ee9ac2e0f3a4e12814893972e63 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Thu, 15 Sep 2022 13:11:14 +0200 Subject: [PATCH] x86/entry: Make sync_regs() invocation a tail call No point in having a call there. Spare the call/ret overhead. Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Thomas Gleixner Signed-off-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/r/20220915111146.539578813@infradead.org --- arch/x86/entry/entry_64.S | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-) diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S index 5c578a7..b24b84b 100644 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -1062,11 +1062,8 @@ 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 @@ -1124,7 +1121,7 @@ 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) -- 2.7.4