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ptrace/x86: Introduce set_task_blockstep() helper 

No functional changes, preparation for the next fix and for uprobes
single-step fixes.

Move the code playing with TIF_BLOCKSTEP/DEBUGCTLMSR_BTF into the
new helper, set_task_blockstep().

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
This commit is contained in:
Oleg Nesterov 2012-08-03 17:31:46 +02:00
parent bdc1e47217
commit 848e8f5f0a
1 changed files with 21 additions and 20 deletions
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41
arch/x86/kernel/step.c
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@ -157,6 +157,21 @@ static int enable_single_step(struct task_struct *child)
return 1;
}
static void set_task_blockstep(struct task_struct *task, bool on)
{
unsigned long debugctl;
debugctl = get_debugctlmsr();
if (on) {
debugctl |= DEBUGCTLMSR_BTF;
set_tsk_thread_flag(task, TIF_BLOCKSTEP);
} else {
debugctl &= ~DEBUGCTLMSR_BTF;
clear_tsk_thread_flag(task, TIF_BLOCKSTEP);
}
update_debugctlmsr(debugctl);
}
/*
* Enable single or block step.
*/
@ -169,19 +184,10 @@ static void enable_step(struct task_struct *child, bool block)
* So no one should try to use debugger block stepping in a program
* that uses user-mode single stepping itself.
*/
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);
}
if (enable_single_step(child) && block)
set_task_blockstep(child, true);
else if (test_tsk_thread_flag(child, TIF_BLOCKSTEP))
set_task_blockstep(child, false);
}
void user_enable_single_step(struct task_struct *child)
@ -199,13 +205,8 @@ void user_disable_single_step(struct task_struct *child)
/*
* Make sure block stepping (BTF) is disabled.
*/
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);
}
if (test_tsk_thread_flag(child, TIF_BLOCKSTEP))
set_task_blockstep(child, false);
/* Always clear TIF_SINGLESTEP... */
clear_tsk_thread_flag(child, TIF_SINGLESTEP);