Commit-ID:  4fbb39108f972437c44e5ffa781b56635d496826
Gitweb:     https://git.kernel.org/tip/4fbb39108f972437c44e5ffa781b56635d496826
Author:     Andy Lutomirski <l...@kernel.org>
AuthorDate: Thu, 2 Nov 2017 00:59:03 -0700
Committer:  Ingo Molnar <mi...@kernel.org>
CommitDate: Thu, 2 Nov 2017 11:04:39 +0100

x86/entry/64: Use pop instead of movq in syscall_return_via_sysret

Saves 64 bytes.

Signed-off-by: Andy Lutomirski <l...@kernel.org>
Reviewed-by: Borislav Petkov <b...@suse.de>
Cc: Borislav Petkov <bpet...@suse.de>
Cc: Brian Gerst <brge...@gmail.com>
Cc: Dave Hansen <dave.han...@intel.com>
Cc: Linus Torvalds <torva...@linux-foundation.org>
Cc: Peter Zijlstra <pet...@infradead.org>
Cc: Thomas Gleixner <t...@linutronix.de>
Link: 
http://lkml.kernel.org/r/6609b7f74ab31c36604ad746e019ea8495aec76c.1509609304.git.l...@kernel.org
Signed-off-by: Ingo Molnar <mi...@kernel.org>
---
 arch/x86/entry/entry_64.S | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 15539644..4f9b446 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -315,10 +315,18 @@ return_from_SYSCALL_64:
         */
 syscall_return_via_sysret:
        /* rcx and r11 are already restored (see code above) */
-       RESTORE_EXTRA_REGS
-       RESTORE_C_REGS_EXCEPT_RCX_R11
-       movq    RSP(%rsp), %rsp
        UNWIND_HINT_EMPTY
+       POP_EXTRA_REGS
+       popq    %rsi    /* skip r11 */
+       popq    %r10
+       popq    %r9
+       popq    %r8
+       popq    %rax
+       popq    %rsi    /* skip rcx */
+       popq    %rdx
+       popq    %rsi
+       popq    %rdi
+       movq    RSP-ORIG_RAX(%rsp), %rsp
        USERGS_SYSRET64
 END(entry_SYSCALL_64)
 

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