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SubjectRe: [PATCH 3/7] ptrace: Introduce set_task_blockstep() helper
* Oleg Nesterov <oleg@redhat.com> [2012-09-03 17:26:06]:

> 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>

> ---
> arch/x86/kernel/step.c | 41 +++++++++++++++++++++--------------------
> 1 files changed, 21 insertions(+), 20 deletions(-)
>
> diff --git a/arch/x86/kernel/step.c b/arch/x86/kernel/step.c
> index c346d11..7a51498 100644
> --- a/arch/x86/kernel/step.c
> +++ b/arch/x86/kernel/step.c
> @@ -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);
> --
> 1.5.5.1
>



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