diff options
| author | Peter Zijlstra <a.p.zijlstra@chello.nl> | 2010-03-25 14:51:51 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2010-03-26 11:33:57 +0100 |
| commit | ea8e61b7bbc4a2faef77db34eb2db2a2c2372ff6 (patch) | |
| tree | df2998225dc10245ce3d392576a724ab788e456c /arch/x86/kernel | |
| parent | faa4602e47690fb11221e00f9b9697c8dc0d4b19 (diff) | |
x86, ptrace: Fix block-step
Implement ptrace-block-step using TIF_BLOCKSTEP which will set
DEBUGCTLMSR_BTF when set for a task while preserving any other
DEBUGCTLMSR bits.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <20100325135414.017536066@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/x86/kernel')
| -rw-r--r-- | arch/x86/kernel/kprobes.c | 14 | ||||
| -rw-r--r-- | arch/x86/kernel/process.c | 11 | ||||
| -rw-r--r-- | arch/x86/kernel/step.c | 24 | ||||
| -rw-r--r-- | arch/x86/kernel/traps.c | 5 |
4 files changed, 48 insertions, 6 deletions
diff --git a/arch/x86/kernel/kprobes.c b/arch/x86/kernel/kprobes.c index 7a880ad3a20..f2f56c0967b 100644 --- a/arch/x86/kernel/kprobes.c +++ b/arch/x86/kernel/kprobes.c @@ -422,12 +422,22 @@ static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs, static void __kprobes clear_btf(void) { - /* XXX */ + if (test_thread_flag(TIF_BLOCKSTEP)) { + unsigned long debugctl = get_debugctlmsr(); + + debugctl &= ~DEBUGCTLMSR_BTF; + update_debugctlmsr(debugctl); + } } static void __kprobes restore_btf(void) { - /* XXX */ + if (test_thread_flag(TIF_BLOCKSTEP)) { + unsigned long debugctl = get_debugctlmsr(); + + debugctl |= DEBUGCTLMSR_BTF; + update_debugctlmsr(debugctl); + } } void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri, diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index 1a60beb32ed..8328009416d 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -195,6 +195,17 @@ void __switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p, prev = &prev_p->thread; next = &next_p->thread; + if (test_tsk_thread_flag(prev_p, TIF_BLOCKSTEP) ^ + test_tsk_thread_flag(next_p, TIF_BLOCKSTEP)) { + unsigned long debugctl = get_debugctlmsr(); + + debugctl &= ~DEBUGCTLMSR_BTF; + if (test_tsk_thread_flag(next_p, TIF_BLOCKSTEP)) + debugctl |= DEBUGCTLMSR_BTF; + + update_debugctlmsr(debugctl); + } + if (test_tsk_thread_flag(prev_p, TIF_NOTSC) ^ test_tsk_thread_flag(next_p, TIF_NOTSC)) { /* prev and next are different */ 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); diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index e3da5d726a3..36f1bd9f8e7 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -544,6 +544,11 @@ dotraplinkage void __kprobes do_debug(struct pt_regs *regs, long error_code) /* DR6 may or may not be cleared by the CPU */ set_debugreg(0, 6); + /* + * The processor cleared BTF, so don't mark that we need it set. + */ + clear_tsk_thread_flag(tsk, TIF_BLOCKSTEP); + /* Store the virtualized DR6 value */ tsk->thread.debugreg6 = dr6; |