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Diffstat (limited to 'arch/x86/kernel/step.c')
-rw-r--r--arch/x86/kernel/step.c24
1 files changed, 20 insertions, 4 deletions
diff --git a/arch/x86/kernel/step.c b/arch/x86/kernel/step.c
index 7beba0769a8..58de45ee08b 100644
--- a/arch/x86/kernel/step.c
+++ b/arch/x86/kernel/step.c
@@ -169,9 +169,19 @@ static void enable_step(struct task_struct *child, bool block)
* So noone should try to use debugger block stepping in a program
* that uses user-mode single stepping itself.
*/
- if (!enable_single_step(child))
- return;
- /* XXX */
+ if (enable_single_step(child) && block) {
+ unsigned long debugctl = get_debugctlmsr();
+
+ debugctl |= DEBUGCTLMSR_BTF;
+ update_debugctlmsr(debugctl);
+ set_tsk_thread_flag(child, TIF_BLOCKSTEP);
+ } else if (test_tsk_thread_flag(child, TIF_BLOCKSTEP)) {
+ unsigned long debugctl = get_debugctlmsr();
+
+ debugctl &= ~DEBUGCTLMSR_BTF;
+ update_debugctlmsr(debugctl);
+ clear_tsk_thread_flag(child, TIF_BLOCKSTEP);
+ }
}
void user_enable_single_step(struct task_struct *child)
@@ -189,7 +199,13 @@ void user_disable_single_step(struct task_struct *child)
/*
* Make sure block stepping (BTF) is disabled.
*/
- /* XXX */
+ if (test_tsk_thread_flag(child, TIF_BLOCKSTEP)) {
+ unsigned long debugctl = get_debugctlmsr();
+
+ debugctl &= ~DEBUGCTLMSR_BTF;
+ update_debugctlmsr(debugctl);
+ clear_tsk_thread_flag(child, TIF_BLOCKSTEP);
+ }
/* Always clear TIF_SINGLESTEP... */
clear_tsk_thread_flag(child, TIF_SINGLESTEP);