[External] Re: [PATCH v5] riscv: add userland instruction dump to RISC-V splats

[yunhui cui]

Hi Björn,

On Sat, Sep 9, 2023 at 2:01 AM Björn Töpel <bjorn at kernel.org> wrote:
>
> yunhui cui <cuiyunhui at bytedance.com> writes:
>
> > Hi Björn，
> >
> > On Fri, Sep 8, 2023 at 2:45 AM Björn Töpel <bjorn at kernel.org> wrote:
> >>
> >> Yunhui Cui <cuiyunhui at bytedance.com> writes:
> >>
> >> > Add userland instruction dump and rename dump_kernel_instr()
> >> > to dump_instr().
> >> >
> >> > An example:
> >> > [    0.822439] Freeing unused kernel image (initmem) memory: 6916K
> >> > [    0.823817] Run /init as init process
> >> > [    0.839411] init[1]: unhandled signal 4 code 0x1 at 0x000000000005be18 in bb[10000+5fb000]
> >> > [    0.840751] CPU: 0 PID: 1 Comm: init Not tainted 5.14.0-rc4-00049-gbd644290aa72-dirty #187
> >> > [    0.841373] Hardware name:  , BIOS
> >> > [    0.841743] epc : 000000000005be18 ra : 0000000000079e74 sp : 0000003fffcafda0
> >> > [    0.842271]  gp : ffffffff816e9dc8 tp : 0000000000000000 t0 : 0000000000000000
> >> > [    0.842947]  t1 : 0000003fffc9fdf0 t2 : 0000000000000000 s0 : 0000000000000000
> >> > [    0.843434]  s1 : 0000000000000000 a0 : 0000003fffca0190 a1 : 0000003fffcafe18
> >> > [    0.843891]  a2 : 0000000000000000 a3 : 0000000000000000 a4 : 0000000000000000
> >> > [    0.844357]  a5 : 0000000000000000 a6 : 0000000000000000 a7 : 0000000000000000
> >> > [    0.844803]  s2 : 0000000000000000 s3 : 0000000000000000 s4 : 0000000000000000
> >> > [    0.845253]  s5 : 0000000000000000 s6 : 0000000000000000 s7 : 0000000000000000
> >> > [    0.845722]  s8 : 0000000000000000 s9 : 0000000000000000 s10: 0000000000000000
> >> > [    0.846180]  s11: 0000000000d144e0 t3 : 0000000000000000 t4 : 0000000000000000
> >> > [    0.846616]  t5 : 0000000000000000 t6 : 0000000000000000
> >> > [    0.847204] status: 0000000200000020 badaddr: 00000000f0028053 cause: 0000000000000002
> >> > [    0.848219] Code: f06f ff5f 3823 fa11 0113 fb01 2e23 0201 0293 0000 (8053) f002
> >> > [    0.851016] Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000004
> >> >
> >> > Signed-off-by: Yunhui Cui <cuiyunhui at bytedance.com>
> >> > ---
> >> >  arch/riscv/kernel/traps.c | 19 ++++++++++++++++---
> >> >  1 file changed, 16 insertions(+), 3 deletions(-)
> >> >
> >> > diff --git a/arch/riscv/kernel/traps.c b/arch/riscv/kernel/traps.c
> >> > index f798c853bede..923b49c38985 100644
> >> > --- a/arch/riscv/kernel/traps.c
> >> > +++ b/arch/riscv/kernel/traps.c
> >> > @@ -33,7 +33,19 @@ int show_unhandled_signals = 1;
> >> >
> >> >  static DEFINE_SPINLOCK(die_lock);
> >> >
> >> > -static void dump_kernel_instr(const char *loglvl, struct pt_regs *regs)
> >> > +static int copy_code(struct pt_regs *regs, u16 *val, const u16 *insns)
> >> > +{
> >> > +     if (!user_mode(regs))
> >> > +             return get_kernel_nofault(*val, insns);
> >> > +
> >> > +     /* The user space code from other tasks cannot be accessed. */
> >> > +     if (regs != task_pt_regs(current))
> >> > +             return -EPERM;
> >> > +
> >> > +     return copy_from_user_nofault(val, insns, sizeof(*val));
> >>
> >> Hmm, I think you missed the actual problem in [1]. I'm still getting:
> >>
> >>   |   CHECK   arch/riscv/kernel/traps.c
> >>   | arch/riscv/kernel/traps.c:46:44: warning: incorrect type in argument 2 (different address spaces)
> >>   | arch/riscv/kernel/traps.c:46:44:    expected void const [noderef] __user *src
> >>   | arch/riscv/kernel/traps.c:46:44:    got unsigned short const [usertype] *insns
> >>
> >
> > How did the warnings above come about? I don't have one locally. What
> > is your risc-v gcc version?
>
> It's from the "sparse" tool. Pass "C=1" to make. Unfortunately RV sparse
> needs to be built manually: https://github.com/ConchuOD/sparse
>
>  | make ARCH=riscv CROSS_COMPILE=riscv64-linux-gnu- C=1 W=1 arch/riscv/kernel/traps.o

I used sparse to check locally and found that there were indeed
warnings. I'll post v6 to solve it.


Thanks，
Yunhui