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    SubjectRe: [PATCH 5/6] x86: Remove useless unwinder backlink from irq regs saving
    >>> On 02.07.11 at 18:29, Frederic Weisbecker <fweisbec@gmail.com> wrote:
    > The unwinder backlink in interrupt entry is very useless.
    > It's actually not part of the stack frame chain and thus is
    > never used.

    I very much doubt this - see dump_trace()'s comment in its IRQ-stack
    related code portion (and the corresponding use of irq_stack_end[-1]).

    Jan

    > 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>
    > ---
    > arch/x86/kernel/entry_64.S | 1 -
    > 1 files changed, 0 insertions(+), 1 deletions(-)
    >
    > diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
    > index 20dc8e6..6131432 100644
    > --- 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:
    > */






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