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From:   Greentime Hu <green.hu@gmail.com>
Date:   Fri, 23 Aug 2019 16:56:04 +0800
Message-ID: <CAEbi=3fbe9zbsLyfA=s9gHtAFJrp5Ox0jWoAqcZudQ_xODicgA@mail.gmail.com>
Subject: Re: [PATCH V5 1/3] riscv: Add perf callchain support
To:     Mao Han <han_mao@c-sky.com>
Cc:     linux-riscv@lists.infradead.org,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        linux-arch <linux-arch@vger.kernel.org>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Palmer Dabbelt <palmer@sifive.com>,
        Christoph Hellwig <hch@lst.de>, Guo Ren <guoren@kernel.org>
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Hi Mao,

Mao Han <han_mao@c-sky.com> =E6=96=BC 2019=E5=B9=B48=E6=9C=8823=E6=97=A5 =
=E9=80=B1=E4=BA=94 =E4=B8=8B=E5=8D=882:16=E5=AF=AB=E9=81=93=EF=BC=9A

>
> This patch add support for perf callchain sampling on riscv platform.
> The return address of leaf function is retrieved from pt_regs as
> it is not saved in the outmost frame.
>
> Signed-off-by: Mao Han <han_mao@c-sky.com>
> Cc: Paul Walmsley <paul.walmsley@sifive.com>
> Cc: Greentime Hu <green.hu@gmail.com>
> Cc: Palmer Dabbelt <palmer@sifive.com>
> Cc: linux-riscv <linux-riscv@lists.infradead.org>
> Cc: Christoph Hellwig <hch@lst.de>
> Cc: Guo Ren <guoren@kernel.org>
> ---
>  arch/riscv/Makefile                |   3 +
>  arch/riscv/kernel/Makefile         |   3 +-
>  arch/riscv/kernel/perf_callchain.c | 115 +++++++++++++++++++++++++++++++=
++++++
>  3 files changed, 120 insertions(+), 1 deletion(-)
>  create mode 100644 arch/riscv/kernel/perf_callchain.c

I just tested "./perf record -e cpu-clock --call-graph fp ls" on
Unleashed board and I got this failure.
I take a look at it. It seem failed in here. Do you have any idea?
It seems fine in Qemu.

1 *frame =3D *((struct stackframe *)frame->fp - 1);
ffffffe0001a198c: 00863a83 ld s5,8(a2)
ffffffe0001a1990: ff093903 ld s2,-16(s2)

./perf record -e cpu-clock --call-graph fp ls
[ 9619.423884] hrtimer: interrupt took 733000 ns
[ 9619.977017] Unable to handle kernel paging request at virtual
address ffffffffffffff94
[ 9620.214736] Oops [#1]
[ 9620.289893] Modules linked in:
[ 9620.391378] CPU: 0 PID: 264 Comm: ls Not tainted
5.3.0-rc5-00003-gb008f6bcd67c #4
[ 9620.640176] sepc: ffffffe0001a198c ra : ffffffe0001a199a sp :
ffffffe000093720
[ 9620.880366] gp : ffffffe00097dad8 tp : ffffffe000082e40 t0 : 00000000000=
46000
[ 9621.120564] t1 : 0000000000000002 t2 : 0000000000000007 s0 : ffffffe0000=
93760
[ 9621.360768] s1 : ffffffe000093788 a0 : 0000000000000003 a1 : 00000000000=
00000
[ 9621.600991] a2 : ffffffffffffff8c a3 : 0000000000001fa0 a4 : 00000000000=
00010
[ 9621.841181] a5 : 0000000000000002 a6 : 0000000000000001 a7 : ffffffe079b=
34e10
[ 9622.081400] s2 : ffffffffffffff9c s3 : ffffffe000000000 s4 : 00000000000=
01ff8
[ 9622.321618] s5 : ffffffe000093da0 s6 : ffffffe00097d540 s7 : ffffffe07a1=
517a0
[ 9622.561811] s8 : 000008bf01c7ff60 s9 : ffffffe000235b2a s10: 00000002000=
00120
[ 9622.802015] s11: 0000000000000001 t3 : ffffffe079b34e00 t4 : 00000000000=
00001
[ 9623.042194] t5 : 0000000000000008 t6 : ffffffe0009208d0
[ 9623.218785] sstatus: 0000000200000100 sbadaddr: ffffffffffffff94
scause: 000000000000000d
[ 9623.490850] ---[ end trace 49043f28e856d84d ]---
[ 9623.644217] Kernel panic - not syncing: Fatal exception in interrupt
[ 9623.855470] SMP: stopping secondary CPUs
[ 9623.985955] ---[ end Kernel panic - not syncing: Fatal exception in
interrupt ]---