x86/entry/64/compat: Save one instruction in entry_INT80_compat()

As %rdi is never user except in the following push, there is no
need to restore %rdi to the original value.

Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: luto@amacapital.net
Cc: viro@zeniv.linux.org.uk
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/arch/x86/entry/entry_64_compat.S b/arch/x86/entry/entry_64_compat.S
index ff61b7b..08425c4 100644 (file)
--- a/arch/x86/entry/entry_64_compat.S
+++ b/arch/x86/entry/entry_64_compat.S
@@ -363,9 +363,7 @@ ENTRY(entry_INT80_compat)
        pushq   2*8(%rdi)               /* regs->ip */
        pushq   1*8(%rdi)               /* regs->orig_ax */
 
-       movq    (%rdi), %rdi            /* restore %rdi */
-
-       pushq   %rdi                    /* pt_regs->di */
+       pushq   (%rdi)                  /* pt_regs->di */
        pushq   %rsi                    /* pt_regs->si */
        pushq   %rdx                    /* pt_regs->dx */
        pushq   %rcx                    /* pt_regs->cx */