Messages in this thread | | | From | Björn Töpel <> | Subject | Re: [PATCH v3] riscv: add userland instruction dump to RISC-V splats | Date | Thu, 17 Aug 2023 15:27:14 +0200 |
| |
Yunhui Cui <cuiyunhui@bytedance.com> writes:
> Added userland instruction dump in dump_kernel_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 | 10 +++++++--- > include/linux/uaccess.h | 5 +++++ > 2 files changed, 12 insertions(+), 3 deletions(-) > > diff --git a/arch/riscv/kernel/traps.c b/arch/riscv/kernel/traps.c > index f910dfccbf5d..a6a850e42d59 100644 > --- a/arch/riscv/kernel/traps.c > +++ b/arch/riscv/kernel/traps.c > @@ -33,7 +33,7 @@ int show_unhandled_signals = 1; > > static DEFINE_SPINLOCK(die_lock); > > -static void dump_kernel_instr(const char *loglvl, struct pt_regs *regs) > +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 +42,10 @@ 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]); > + if (user_mode(regs)) > + bad = get_user_nofault(val, &insns[i]); > + else > + bad = get_kernel_nofault(val, &insns[i]); > if (!bad) { > p += sprintf(p, i == 0 ? "(%04hx) " : "%04hx ", val); > } else { > @@ -71,7 +74,7 @@ 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 +107,7 @@ 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); > diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h > index 3064314f4832..ba8cb37a7241 100644 > --- a/include/linux/uaccess.h > +++ b/include/linux/uaccess.h > @@ -385,6 +385,11 @@ long strncpy_from_user_nofault(char *dst, const void __user *unsafe_addr, > long count); > long strnlen_user_nofault(const void __user *unsafe_addr, long count); > > +#define get_user_nofault(val, ptr) ({ \ > + const typeof(val) *__gk_ptr = (ptr); \ > + copy_from_user_nofault(&(val), __gk_ptr, sizeof(val));\ > +}) > +
Your previous version had a check: | /* The user space code from other tasks cannot be accessed. */ | if (regs != task_pt_regs(current)) | return -EPERM;
Why was that left out? Is it not needed?
Your get_user_nofault is only used in this file, so maybe it's better to do what x86 does, and introduce a static "copy_code()" that deals with the user/kernel checks/copy?
Björn
| |