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.