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Diffstat (limited to 'arch/x86/kernel/step.c')
-rw-r--r--arch/x86/kernel/step.c18
1 files changed, 13 insertions, 5 deletions
diff --git a/arch/x86/kernel/step.c b/arch/x86/kernel/step.c
index f55c003f5b6..21ea22fda5f 100644
--- a/arch/x86/kernel/step.c
+++ b/arch/x86/kernel/step.c
@@ -169,9 +169,14 @@ static void enable_step(struct task_struct *child, bool block)
*/
if (enable_single_step(child) && block) {
set_tsk_thread_flag(child, TIF_DEBUGCTLMSR);
- write_debugctlmsr(child, DEBUGCTLMSR_BTF);
- } else if (test_and_clear_tsk_thread_flag(child, TIF_DEBUGCTLMSR)) {
- write_debugctlmsr(child, 0);
+ write_debugctlmsr(child,
+ child->thread.debugctlmsr | DEBUGCTLMSR_BTF);
+ } else {
+ write_debugctlmsr(child,
+ child->thread.debugctlmsr & ~TIF_DEBUGCTLMSR);
+
+ if (!child->thread.debugctlmsr)
+ clear_tsk_thread_flag(child, TIF_DEBUGCTLMSR);
}
}
@@ -190,8 +195,11 @@ void user_disable_single_step(struct task_struct *child)
/*
* Make sure block stepping (BTF) is disabled.
*/
- if (test_and_clear_tsk_thread_flag(child, TIF_DEBUGCTLMSR))
- write_debugctlmsr(child, 0);
+ write_debugctlmsr(child,
+ child->thread.debugctlmsr & ~TIF_DEBUGCTLMSR);
+
+ if (!child->thread.debugctlmsr)
+ clear_tsk_thread_flag(child, TIF_DEBUGCTLMSR);
/* Always clear TIF_SINGLESTEP... */
clear_tsk_thread_flag(child, TIF_SINGLESTEP);