Re: [PATCH] perf: perf can not parser the backtrace of app in the 32bit system and 64bit kernel.

[Jiping Ma]

Hi, Will

Please help to review the patch.

Thanks,
Jiping

On 04/29/2020 12:51 PM, Jiping Ma wrote:
> We test it as the following steps.
> # gcc -g -mthumb -gdwarf -o test test.c
> # export CALLGRAPH=dwarf
> #(./perftest ./test profiling 1; cd ./profiling/; perf script)
>
> Thanks,
> Jiping
>
> On 04/29/2020 12:01 PM, Jiping Ma wrote:
> > Record PC value from regs[15], it should be regs[32], which cause perf
> > parser the backtrace failed.
> >
> > Signed-off-by: Jiping Ma <jiping.ma2@xxxxxxxxxxxxx>
> > ---
> > Â arch/arm64/kernel/perf_regs.c | 4 ++++
> > Â 1 file changed, 4 insertions(+)
> >
> > diff --git a/arch/arm64/kernel/perf_regs.c 
> > b/arch/arm64/kernel/perf_regs.c
> > index 0bbac61..04088e6 100644
> > --- a/arch/arm64/kernel/perf_regs.c
> > +++ b/arch/arm64/kernel/perf_regs.c
> > @@ -32,6 +32,10 @@ u64 perf_reg_value(struct pt_regs *regs, int idx)
> > ÂÂÂÂÂ if ((u32)idx == PERF_REG_ARM64_PC)
> > ÂÂÂÂÂÂÂÂÂ return regs->pc;
> > Â +ÂÂÂ if (perf_reg_abi(current) == PERF_SAMPLE_REGS_ABI_32
> > +ÂÂÂÂÂÂÂ && idx == 15)
> > +ÂÂÂÂÂÂÂ return regs->regs[PERF_REG_ARM64_PC];
> > +
> > ÂÂÂÂÂ return regs->regs[idx];
> > Â }