On 08/01, Sebastian Andrzej Siewior wrote:
>
> So a patch like
> --- a/arch/x86/kernel/step.c
> +++ b/arch/x86/kernel/step.c
> @@ -173,8 +173,8 @@ static void enable_step(struct task_struct *child,
> bool block)
> unsigned long debugctl = get_debugctlmsr();
>
> debugctl |= DEBUGCTLMSR_BTF;
> - update_debugctlmsr(debugctl);
> set_tsk_thread_flag(child, TIF_BLOCKSTEP);
> + update_debugctlmsr(debugctl);
> } else if (test_tsk_thread_flag(child, TIF_BLOCKSTEP)) {
> unsigned long debugctl = get_debugctlmsr();
>
> should fix the race
No, I don't think it can fix something ;) or make any difference.
> and _yes_ I also would follow your suggestion to
> remove this update_debugctlmsr() here since switch_to() should do this.
Agreed, but once again, uprobes needs it if child == current (but we should
move this code into the trivial helper). If we change (I hope) uprobes to
avoid user_enable_single_step() we will export the helper.
Oleg.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
