diff options
Diffstat (limited to 'arch/x86/kernel/step.c')
-rw-r--r-- | arch/x86/kernel/step.c | 53 |
1 files changed, 33 insertions, 20 deletions
diff --git a/arch/x86/kernel/step.c b/arch/x86/kernel/step.c index c346d1161488..cd3b2438a980 100644 --- a/arch/x86/kernel/step.c +++ b/arch/x86/kernel/step.c | |||
@@ -157,6 +157,33 @@ static int enable_single_step(struct task_struct *child) | |||
157 | return 1; | 157 | return 1; |
158 | } | 158 | } |
159 | 159 | ||
160 | void set_task_blockstep(struct task_struct *task, bool on) | ||
161 | { | ||
162 | unsigned long debugctl; | ||
163 | |||
164 | /* | ||
165 | * Ensure irq/preemption can't change debugctl in between. | ||
166 | * Note also that both TIF_BLOCKSTEP and debugctl should | ||
167 | * be changed atomically wrt preemption. | ||
168 | * FIXME: this means that set/clear TIF_BLOCKSTEP is simply | ||
169 | * wrong if task != current, SIGKILL can wakeup the stopped | ||
170 | * tracee and set/clear can play with the running task, this | ||
171 | * can confuse the next __switch_to_xtra(). | ||
172 | */ | ||
173 | local_irq_disable(); | ||
174 | debugctl = get_debugctlmsr(); | ||
175 | if (on) { | ||
176 | debugctl |= DEBUGCTLMSR_BTF; | ||
177 | set_tsk_thread_flag(task, TIF_BLOCKSTEP); | ||
178 | } else { | ||
179 | debugctl &= ~DEBUGCTLMSR_BTF; | ||
180 | clear_tsk_thread_flag(task, TIF_BLOCKSTEP); | ||
181 | } | ||
182 | if (task == current) | ||
183 | update_debugctlmsr(debugctl); | ||
184 | local_irq_enable(); | ||
185 | } | ||
186 | |||
160 | /* | 187 | /* |
161 | * Enable single or block step. | 188 | * Enable single or block step. |
162 | */ | 189 | */ |
@@ -169,19 +196,10 @@ static void enable_step(struct task_struct *child, bool block) | |||
169 | * So no one should try to use debugger block stepping in a program | 196 | * So no one should try to use debugger block stepping in a program |
170 | * that uses user-mode single stepping itself. | 197 | * that uses user-mode single stepping itself. |
171 | */ | 198 | */ |
172 | if (enable_single_step(child) && block) { | 199 | if (enable_single_step(child) && block) |
173 | unsigned long debugctl = get_debugctlmsr(); | 200 | set_task_blockstep(child, true); |
174 | 201 | else if (test_tsk_thread_flag(child, TIF_BLOCKSTEP)) | |
175 | debugctl |= DEBUGCTLMSR_BTF; | 202 | set_task_blockstep(child, false); |
176 | update_debugctlmsr(debugctl); | ||
177 | set_tsk_thread_flag(child, TIF_BLOCKSTEP); | ||
178 | } else if (test_tsk_thread_flag(child, TIF_BLOCKSTEP)) { | ||
179 | unsigned long debugctl = get_debugctlmsr(); | ||
180 | |||
181 | debugctl &= ~DEBUGCTLMSR_BTF; | ||
182 | update_debugctlmsr(debugctl); | ||
183 | clear_tsk_thread_flag(child, TIF_BLOCKSTEP); | ||
184 | } | ||
185 | } | 203 | } |
186 | 204 | ||
187 | void user_enable_single_step(struct task_struct *child) | 205 | void user_enable_single_step(struct task_struct *child) |
@@ -199,13 +217,8 @@ void user_disable_single_step(struct task_struct *child) | |||
199 | /* | 217 | /* |
200 | * Make sure block stepping (BTF) is disabled. | 218 | * Make sure block stepping (BTF) is disabled. |
201 | */ | 219 | */ |
202 | if (test_tsk_thread_flag(child, TIF_BLOCKSTEP)) { | 220 | if (test_tsk_thread_flag(child, TIF_BLOCKSTEP)) |
203 | unsigned long debugctl = get_debugctlmsr(); | 221 | set_task_blockstep(child, false); |
204 | |||
205 | debugctl &= ~DEBUGCTLMSR_BTF; | ||
206 | update_debugctlmsr(debugctl); | ||
207 | clear_tsk_thread_flag(child, TIF_BLOCKSTEP); | ||
208 | } | ||
209 | 222 | ||
210 | /* Always clear TIF_SINGLESTEP... */ | 223 | /* Always clear TIF_SINGLESTEP... */ |
211 | clear_tsk_thread_flag(child, TIF_SINGLESTEP); | 224 | clear_tsk_thread_flag(child, TIF_SINGLESTEP); |