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

[yunhui cui]

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?

This is mine:

/opt/riscv/bin/riscv64-unknown-linux-gnu-gcc -v
Using built-in specs.
COLLECT_GCC=/opt/riscv/bin/riscv64-unknown-linux-gnu-gcc
COLLECT_LTO_WRAPPER=/opt/riscv/libexec/gcc/riscv64-unknown-linux-gnu/12.2.0/lto-wrapper
Target: riscv64-unknown-linux-gnu
Configured with: .../riscv-gnu-toolchain/gcc/configure
--target=riscv64-unknown-linux-gnu --prefix=/opt/riscv
--with-sysroot=/opt/riscv/sysroot --with-pkgversion=g2ee5e430018
--with-system-zlib --enable-shared --enable-tls
--enable-languages=c,c++,fortran --disable-libmudflap --disable-libssp
--disable-libquadmath --disable-libsanitizer --disable-nls
--disable-bootstrap --src=.../riscv_acpi/riscv-gnu-toolchain/gcc
--disable-multilib --with-abi=lp64d --with-arch=rv64imafdc
--with-tune=rocket --with-isa-spec=2.2 'CFLAGS_FOR_TARGET=-O2
-mcmodel=medlow' 'CXXFLAGS_FOR_TARGET=-O2   -mcmodel=medlow'
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 12.2.0 (g2ee5e430018)

Thanks,
Yunhui