On 07/14/2017, 07:22 PM, Josh Poimboeuf wrote:
> +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;
> +
> + /*
> + * Refuse to unwind the stack of a task while it's executing on another
> + * CPU. This check is racy, but that's ok: the unwinder has other
> + * checks to prevent it from going off the rails.
> + */
> + if (task_on_another_cpu(task))
> + goto done;
> +
> + if (regs) {
> + if (user_mode(regs))
> + goto done;
> +
> + state->ip = regs->ip;
> + state->sp = kernel_stack_pointer(regs);
> + state->bp = regs->bp;
> + state->regs = regs;
> + state->full_regs = true;
> + state->signal = true;
> +
> + } else if (task == current) {
> + 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));
> +
> + } else {
> + struct inactive_task_frame *frame = (void *)task->thread.sp;
> +
> + state->ip = frame->ret_addr;
> + state->sp = task->thread.sp;
> + state->bp = frame->bp;
I wonder, if the reads from 'frame' should have READ_ONCE_NOCHECK for
the same reason as in:
commit 84936118bdf37bda513d4a361c38181a216427e0
Author: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Date: Mon Jan 9 12:00:23 2017 -0600
x86/unwind: Disable KASAN checks for non-current tasks
?
thanks,
--
js
suse labs
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