x86: Remove useless unwinder backlink from irq regs saving

The unwinder backlink in interrupt entry is very useless.
It's actually not part of the stack frame chain and thus is
never used.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jan Beulich <JBeulich@novell.com>

diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index 20dc8e6b6d8050be24883d10853c7ce2eaf5ca22..6131432c5afaab402f5cb40d4e53c2c45bf2be75 100644 (file)
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -327,7 +327,6 @@ ENDPROC(native_usergs_sysret64)
        jne 2f
        mov PER_CPU_VAR(irq_stack_ptr),%rsp
        EMPTY_FRAME 0
-       pushq_cfi %rbp                  /* backlink for unwinder */
        /*
         * We entered an interrupt context - irqs are off:
         */