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[PATCH v4] riscv: add userland instruction dump to RISC-V splats

Yunhui Cui posted 1 patch 2 years, 4 months ago
There is a newer version of this series
arch/riscv/kernel/traps.c | 24 +++++++++++++++++++++---
1 file changed, 21 insertions(+), 3 deletions(-)
[PATCH v4] riscv: add userland instruction dump to RISC-V splats
Posted by Yunhui Cui 2 years, 4 months ago 
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@bytedance.com>
---
 arch/riscv/kernel/traps.c | 24 +++++++++++++++++++++---
 1 file changed, 21 insertions(+), 3 deletions(-)

diff --git a/arch/riscv/kernel/traps.c b/arch/riscv/kernel/traps.c
index f798c853bede..69b5d18b5ae9 100644
--- a/arch/riscv/kernel/traps.c
+++ b/arch/riscv/kernel/traps.c
@@ -33,7 +33,24 @@ int show_unhandled_signals = 1;
 
 static DEFINE_SPINLOCK(die_lock);
 
-static void dump_kernel_instr(const char *loglvl, struct pt_regs *regs)
+#define get_user_nofault(val, ptr) ({				\
+	const typeof(val) *__gk_ptr = (ptr);			\
+	copy_from_user_nofault(&(val), __gk_ptr, sizeof(val));\
+})
+
+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 get_user_nofault(*val, insns);
+}
+
+static void dump_instr(const char *loglvl, struct pt_regs *regs)
 {
 	char str[sizeof("0000 ") * 12 + 2 + 1], *p = str;
 	const u16 *insns = (u16 *)instruction_pointer(regs);
@@ -42,7 +59,7 @@ static void dump_kernel_instr(const char *loglvl, struct pt_regs *regs)
 	int i;
 
 	for (i = -10; i < 2; i++) {
-		bad = get_kernel_nofault(val, &insns[i]);
+		bad = copy_code(regs, &val, &insns[i]);
 		if (!bad) {
 			p += sprintf(p, i == 0 ? "(%04hx) " : "%04hx ", val);
 		} else {
@@ -71,7 +88,7 @@ void die(struct pt_regs *regs, const char *str)
 	print_modules();
 	if (regs) {
 		show_regs(regs);
-		dump_kernel_instr(KERN_EMERG, regs);
+		dump_instr(KERN_EMERG, regs);
 	}
 
 	cause = regs ? regs->cause : -1;
@@ -104,6 +121,7 @@ void do_trap(struct pt_regs *regs, int signo, int code, unsigned long addr)
 		print_vma_addr(KERN_CONT " in ", instruction_pointer(regs));
 		pr_cont("\n");
 		__show_regs(regs);
+		dump_instr(KERN_EMERG, regs);
 	}
 
 	force_sig_fault(signo, code, (void __user *)addr);
-- 
2.20.1
Re: [PATCH v4] riscv: add userland instruction dump to RISC-V splats
Posted by Björn Töpel 2 years, 4 months ago 
Yunhui Cui <cuiyunhui@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@bytedance.com>

Nice!

Reviewed-by: Björn Töpel <bjorn@rivosinc.com>
Re: [External] Re: [PATCH v4] riscv: add userland instruction dump to RISC-V splats
Posted by yunhui cui 2 years, 3 months ago 
Hi Björn，

On Fri, Aug 18, 2023 at 9:33 PM Björn Töpel <bjorn@kernel.org> wrote:
>
> Yunhui Cui <cuiyunhui@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@bytedance.com>
>
> Nice!
>
> Reviewed-by: Björn Töpel <bjorn@rivosinc.com>

When can this patch be applied to the linux-next branch?

Thanks,
Yunhui
Re: [External] Re: [PATCH v4] riscv: add userland instruction dump to RISC-V splats
Posted by Björn Töpel 2 years, 3 months ago 
yunhui cui <cuiyunhui@bytedance.com> writes:

> Hi Björn，
>
> On Fri, Aug 18, 2023 at 9:33 PM Björn Töpel <bjorn@kernel.org> wrote:
>>
>> Yunhui Cui <cuiyunhui@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@bytedance.com>
>>
>> Nice!
>>
>> Reviewed-by: Björn Töpel <bjorn@rivosinc.com>
>
> When can this patch be applied to the linux-next branch?

It looks like you're getting a sparse warning on the patch [1], and
that's probably why it hasn't been considered. You need something like:

--
diff --git a/arch/riscv/kernel/traps.c b/arch/riscv/kernel/traps.c
index 69b5d18b5ae9..c5364131b8bd 100644
--- a/arch/riscv/kernel/traps.c
+++ b/arch/riscv/kernel/traps.c
@@ -34,7 +34,7 @@ int show_unhandled_signals = 1;
 static DEFINE_SPINLOCK(die_lock);
 
 #define get_user_nofault(val, ptr) ({                          \
-       const typeof(val) *__gk_ptr = (ptr);                    \
+       const typeof(val) __user *__gk_ptr = (__force const typeof(val) __user *)(ptr); \
        copy_from_user_nofault(&(val), __gk_ptr, sizeof(val));\
 })
--

IDK, maybe it worth removing the define all together, and just open code
it.

When you're submitting patches, it's a good thing to track patchwork for
warnings/errors.


Björn

[1] https://patchwork.kernel.org/project/linux-riscv/patch/20230818121504.60492-1-cuiyunhui@bytedance.com/
Re: [External] Re: [PATCH v4] riscv: add userland instruction dump to RISC-V splats
Posted by yunhui cui 2 years, 3 months ago 
Hi Björn,

On Fri, Sep 1, 2023 at 5:06 PM Björn Töpel <bjorn@kernel.org> wrote:
>
> yunhui cui <cuiyunhui@bytedance.com> writes:
>
> > Hi Björn，
> >
> > On Fri, Aug 18, 2023 at 9:33 PM Björn Töpel <bjorn@kernel.org> wrote:
> >>
> >> Yunhui Cui <cuiyunhui@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@bytedance.com>
> >>
> >> Nice!
> >>
> >> Reviewed-by: Björn Töpel <bjorn@rivosinc.com>
> >
> > When can this patch be applied to the linux-next branch?
>
> It looks like you're getting a sparse warning on the patch [1], and
> that's probably why it hasn't been considered. You need something like:
>
> --
> diff --git a/arch/riscv/kernel/traps.c b/arch/riscv/kernel/traps.c
> index 69b5d18b5ae9..c5364131b8bd 100644
> --- a/arch/riscv/kernel/traps.c
> +++ b/arch/riscv/kernel/traps.c
> @@ -34,7 +34,7 @@ int show_unhandled_signals = 1;
>  static DEFINE_SPINLOCK(die_lock);
>
>  #define get_user_nofault(val, ptr) ({                          \
> -       const typeof(val) *__gk_ptr = (ptr);                    \
> +       const typeof(val) __user *__gk_ptr = (__force const typeof(val) __user *)(ptr); \
>         copy_from_user_nofault(&(val), __gk_ptr, sizeof(val));\
>  })
> --
>
> IDK, maybe it worth removing the define all together, and just open code
> it.
>
> When you're submitting patches, it's a good thing to track patchwork for
> warnings/errors.
>
>
> Björn
>
> [1] https://patchwork.kernel.org/project/linux-riscv/patch/20230818121504.60492-1-cuiyunhui@bytedance.com/

Okay, I might as well remove the macro, after all, the definition is only here.
I'll update it v5 like:
+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));
+}

Thanks,
Yunhui

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