Re: [PATCH] arm64: ftrace: function_graph: dump real return addr in call trace

[libin]

å 2015/10/20 23:32, Catalin Marinas åé:
> On Thu, Oct 15, 2015 at 10:18:12AM -0400, Steven Rostedt wrote:
> > On Thu, 15 Oct 2015 13:51:33 +0100
> > Will Deacon <will.deacon@xxxxxxx> wrote:
> >
> > > Is this the same old problem caused by e306dfd06fcb ("ARM64: unwind: Fix
> > > PC calculation")? I've said previously that I'm happy to revert that if
> > > we're the only architecture with this behaviour, but Akashi resisted
> > > because there are other issues with ftrace that he was hoping to address
> > > and they would resolve this too.
> >
> > Just a reference, but this patch is pretty much exactly what x86
> > currently has. I wonder if I should make that function generic for all
> > archs to use.
> >
> > If you accept this patch, I can look at what archs do and pull out the
> > common code and place it into the core code and have the archs call
> > that instead.
>
> The difference I see from the sh and x86 version is that we have this -4
> on arm64, introduced by e306dfd06fcb as Will mentioned above (it seemed
> to have caused more problems that it solved). I think we should revert
> that commit first just to be in line with other architectures and then
> apply additional fixes as needed.
>
> Question for Li Bin: is your patch still needed if we revert commit
> e306dfd06fcb?

It still be needed, but it can be implemented in generic for all archs
as Steve suggested.

Thanks,
Li Bin

> Thanks.

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