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Commit 848e8f5f authored by Oleg Nesterov's avatar Oleg Nesterov
Browse files

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: default avatarOleg Nesterov <oleg@redhat.com>
Acked-by: default avatarSrikar Dronamraju <srikar@linux.vnet.ibm.com>
parent bdc1e472

arch/x86/kernel/step.c

+21 −20
Original line number Original line Diff line number Diff line
@@ -157,6 +157,21 @@ static int enable_single_step(struct task_struct *child) 
	return 1;

	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.

 * 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

	 * So no one should try to use debugger block stepping in a program

	 * that uses user-mode single stepping itself.

	 * that uses user-mode single stepping itself.

	 */

	 */

	if (enable_single_step(child) && block) {

	if (enable_single_step(child) && block)

		unsigned long debugctl = get_debugctlmsr();

		set_task_blockstep(child, true);



	else if (test_tsk_thread_flag(child, TIF_BLOCKSTEP))

		debugctl |= DEBUGCTLMSR_BTF;

		set_task_blockstep(child, false);

		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)

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.

	 * Make sure block stepping (BTF) is disabled.

	 */

	 */

	if (test_tsk_thread_flag(child, TIF_BLOCKSTEP)) {

	if (test_tsk_thread_flag(child, TIF_BLOCKSTEP))

		unsigned long debugctl = get_debugctlmsr();

		set_task_blockstep(child, false);



		debugctl &= ~DEBUGCTLMSR_BTF;

		update_debugctlmsr(debugctl);

		clear_tsk_thread_flag(child, TIF_BLOCKSTEP);

	}





	/* Always clear TIF_SINGLESTEP... */

	/* Always clear TIF_SINGLESTEP... */

	clear_tsk_thread_flag(child, TIF_SINGLESTEP);

	clear_tsk_thread_flag(child, TIF_SINGLESTEP);