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

Saves 64 bytes.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Reviewed-by: Borislav Petkov <bp@suse.de>
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/6609b7f74ab31c36604ad746e019ea8495aec76c.1509609304.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 1553964..4f9b446 100644 (file)
--- 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)