Messages in this thread | | | Subject | Re: [RFC PATCH 10/10] x86/unwind: add undwarf unwinder | From | Jiri Slaby <> | Date | Wed, 14 Jun 2017 13:45:41 +0200 |
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On 06/01/2017, 07:44 AM, Josh Poimboeuf wrote: > --- /dev/null > +++ b/arch/x86/kernel/unwind_undwarf.c > @@ -0,0 +1,402 @@ ... > +void __unwind_start(struct unwind_state *state, struct task_struct *task, > + struct pt_regs *regs, unsigned long *first_frame) > +{ > + memset(state, 0, sizeof(*state)); > + state->task = task; > + > + if (regs) { > + if (user_mode(regs)) { > + state->stack_info.type = STACK_TYPE_UNKNOWN; > + return; > + } > + > + state->ip = regs->ip; > + state->sp = kernel_stack_pointer(regs); > + state->bp = regs->bp; > + state->regs = regs; > + > + } else if (task == current) { > + register void *__sp asm(_ASM_SP); > + > + asm volatile("lea (%%rip), %0\n\t" > + "mov %%rsp, %1\n\t" > + "mov %%rbp, %2\n\t" > + : "=r" (state->ip), "=r" (state->sp), > + "=r" (state->bp), "+r" (__sp));
Maybe I don't understand this completely, but what is __sp used for here?
> + state->regs = NULL; > + > + } else {
In DWARF unwinder, we also used to do here:
+#ifdef CONFIG_SMP + } else if (task->on_cpu) { + return; +#endif } else {
> + struct inactive_task_frame *frame = (void *)task->thread.sp;
Since there is no inactive_task_frame for tasks currently running (on other CPUs). At least this always held in the past.
Though, the test is indeed racy.
> + state->ip = frame->ret_addr; > + state->sp = task->thread.sp; > + state->bp = frame->bp; > + state->regs = NULL; > + }
thanks, -- js suse labs
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