x86/asm/entry/64: Simplify retint_kernel label usage, make retint_restore_args label...

Get rid of #define obfuscation of retint_kernel in
CONFIG_PREEMPT case by defining retint_kernel label always, not
only for CONFIG_PREEMPT.

Strip retint_kernel of .global-ness (ENTRY macro) - it has no
users outside of this file.

This looks like cosmetics, but it is not:
"je LABEL" can be optimized to short jump by assember
only if LABEL is not global, for global labels jump is always
a near one with relocation.

Convert retint_restore_args to a local numeric label, making it
clearer that it is not used elsewhere in the file.

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: 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: Will Drewry <wad@chromium.org>
Link: http://lkml.kernel.org/r/1427821211-25099-3-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 f6e37de..1879c55 100644 (file)
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -57,10 +57,6 @@
        .section .entry.text, "ax"
 
 
-#ifndef CONFIG_PREEMPT
-#define retint_kernel retint_restore_args
-#endif
-
 #ifdef CONFIG_PARAVIRT
 ENTRY(native_usergs_sysret64)
        swapgs
@@ -741,18 +737,18 @@ opportunistic_sysret_failed:
        jmp restore_args
 
 /* Returning to kernel space */
+retint_kernel:
 #ifdef CONFIG_PREEMPT
        /* Interrupts are off */
        /* Check if we need preemption */
-ENTRY(retint_kernel)
        cmpl    $0,PER_CPU_VAR(__preempt_count)
-       jnz     retint_restore_args
+       jnz     1f
        bt      $9,EFLAGS(%rsp) /* interrupts were off? */
-       jnc     retint_restore_args
+       jnc     1f
        call    preempt_schedule_irq
        jmp     exit_intr
+1:
 #endif
-retint_restore_args:
        DISABLE_INTERRUPTS(CLBR_ANY)
        /*
         * The iretq could re-enable interrupts: