[kdb] [mort at sgi.com: [PATCH] x86: push old stack address on irqstack for unwinder]

[Martin Hicks]

On Fri, Jan 30, 2009 at 12:24:40PM -0600, Martin Hicks wrote:
> 
> Oops, I meant to CC the KDB list also, but forgot.
> 
> With the reorganization of SAVE_ARGS into a function they removed this
> push onto the interrupt stack.
> 

Peter Anvin accepted this patch, so hopefully it will show up in
2.6.29-rc4


mh

> 
> ----- Forwarded message from Martin Hicks <mort at sgi.com> -----
> 
> From: Martin Hicks <mort at sgi.com>
> Subject: [PATCH] x86: push old stack address on irqstack for unwinder
> Date: Fri, 30 Jan 2009 10:50:54 -0600
> To: tglx at linutronix.de, mingo at redhat.com, hpa at zytor.com,
> 	heukelum at mailshack.com
> Cc: linux-kernel <linux-kernel at vger.kernel.org>
> 
> 
> Hi,
> 
> KDB was using this information.  Could this be pushed towards 2.6.29 please?
> 
> This re-adds the old stack pointer to the top of the irqstack to help
> with unwinding.  It was removed in commit d99015b1abbad743aa049b439c1e1dede6d0fa49
> as part of the save_args out-of-line work.
> 
> Signed-off-by: Martin Hicks <mort at sgi.com>
> ---
>  arch/x86/kernel/entry_64.S |    1 +
>  1 files changed, 1 insertions(+), 0 deletions(-)
> 
> diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
> index e28c7a9..a134621 100644
> --- a/arch/x86/kernel/entry_64.S
> +++ b/arch/x86/kernel/entry_64.S
> @@ -346,6 +346,7 @@ ENTRY(save_args)
>  	popq_cfi %rax			/* move return address... */
>  	mov %gs:pda_irqstackptr,%rsp
>  	EMPTY_FRAME 0
> +	pushq_cfi %rbp			/* backlink for unwinder */
>  	pushq_cfi %rax			/* ... to the new stack */
>  	/*
>  	 * We entered an interrupt context - irqs are off:
> 
> 
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