Re: [PATCH] ARM64: unwind: Fix PC calculation

[Catalin Marinas <Catalin.Marinas@arm.com>]

On 14 Feb 2014, at 19:35, Olof Johansson <olof@lixom.net> wrote:
> The frame PC value in the unwind code used to just take the saved LR
> value and use that.  That's incorrect as a stack trace, since it shows
> the return path stack, not the call path stack.
>
> In particular, it shows faulty information in case the bl is done as
> the very last instruction of one label, since the return point will be
> in the next label. That can easily be seen with tail calls to panic(),
> which is marked __noreturn and thus doesn't have anything useful after it.
>
> Easiest here is to just correct the unwind code and do a -4, to get the
> actual call site for the backtrace instead of the return site.
>
> Signed-off-by: Olof Johansson <olof@lixom.net>
> Cc: stable@vger.kernel.org

Looks fine. I’ll push it sometime next week. Thanks.

Catalin

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