From: Paul Mackerras <paulus@xxxxxxxxx>
Date: Fri, 19 Mar 2010 15:32:02 +1100
> On Thu, Mar 18, 2010 at 09:02:41PM -0700, David Miller wrote:
>> I noticed that the powerpc assembler Paul posted the past few days
>> ignores this "ip" arg passed down and computes it by hand as it
>> walks up the stack chain in assembler. PowerPC therefore might be
>> getting similar inefficiences due to this CALLER_ADDR? stuff.
>
> Well, it would except that CALLER_ADDR1, 2, etc. turn into (0) on
> powerpc because we use the generic definition and we don't define
> CONFIG_FRAME_POINTER (it's meaningless on powerpc because the ABI
> defines that each stack frame always has a pointer to the previous
> frame).
>
> I should fix CALLER_ADDRx on powerpc one day, then we will have the
> extra inefficiency.
Gosh, that CONFIG_FRAME_POINTER dependency is 'nifty', how does the
CALLER_ADDR{1,2} usage made by the scheduler tracepoints work on
powerpc then?
I suppose I could define HAVE_ARCH_CALLER_ADDR and optimize them
on sparc64, similar to what SH is doing.
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