x86/asm/entry/64: Optimize [v]fork/clone stubs

Replace "call func; ret" with "jmp func".

Run-tested.

Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Alexei Starovoitov <ast@plumgrid.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Drewry <wad@chromium.org>
Link: http://lkml.kernel.org/r/1428439424-7258-4-git-send-email-dvlasenk@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index 5380b3a8f3e574bcaf9124e2a67a185d828ab727..ce852565443a54de68f3d1a9d65a6957ad7f4c8c 100644 (file)
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -484,8 +484,7 @@ ENTRY(stub_\func)
        CFI_STARTPROC
        DEFAULT_FRAME 0, 8              /* offset 8: return address */
        SAVE_EXTRA_REGS 8
-       call sys_\func
-       ret
+       jmp sys_\func
        CFI_ENDPROC
 END(stub_\func)
        .endm