Commit f0b67c39 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Thomas Gleixner
Browse files

x86/debug: Move cond_local_irq_enable() block into exc_debug_user() 



The cond_local_irq_enable() block, dealing with vm86 and sending
signals is only relevant for #DB-from-user, move it there.

This then reduces handle_debug() to only the notifier call, so rename
it to notify_debug().

Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Tested-by: default avatarDaniel Thompson <daniel.thompson@linaro.org>
Link: https://lore.kernel.org/r/20200902133201.094265982@infradead.org
parent 4eb5acc3

arch/x86/kernel/traps.c

+29 −29
Original line number Diff line number Diff line
@@ -783,17 +783,10 @@ static __always_inline unsigned long debug_read_clear_dr6(void) 
 *

 * May run on IST stack.

 */

static bool handle_debug(struct pt_regs *regs, unsigned long *dr6)



static bool notify_debug(struct pt_regs *regs, unsigned long *dr6)

{

	struct task_struct *tsk = current;

	bool icebp;



	/*

	 * If dr6 has no reason to give us about the origin of this trap,

	 * then it's very likely the result of an icebp/int01 trap.

	 * User wants a sigtrap for that.

	 */

	icebp = !*dr6;



	/* Store the virtualized DR6 value */

	tsk->thread.debugreg6 = *dr6;
@@ -801,26 +794,9 @@ static bool handle_debug(struct pt_regs *regs, unsigned long *dr6) 
	if (notify_die(DIE_DEBUG, "debug", regs, (long)dr6, 0, SIGTRAP) == NOTIFY_STOP)

		return true;



	/* It's safe to allow irq's after DR6 has been saved */

	cond_local_irq_enable(regs);



	if (v8086_mode(regs)) {

		handle_vm86_trap((struct kernel_vm86_regs *) regs, 0,

				 X86_TRAP_DB);

		goto out;

	}



	/*

	 * Reload dr6, the notifier might have changed it.

	 */

	/* Reload the DR6 value, the notifier might have changed it */

	*dr6 = tsk->thread.debugreg6;



	if (*dr6 & (DR_STEP | DR_TRAP_BITS) || icebp)

		send_sigtrap(regs, 0, get_si_code(*dr6));



out:

	cond_local_irq_disable(regs);



	return false;

}
@@ -864,7 +840,7 @@ static __always_inline void exc_debug_kernel(struct pt_regs *regs, 
	if (!dr6)

		goto out;



	if (handle_debug(regs, &dr6))

	if (notify_debug(regs, &dr6))

		goto out;



	if (WARN_ON_ONCE(dr6 & DR_STEP)) {
@@ -889,6 +865,8 @@ out: 
static __always_inline void exc_debug_user(struct pt_regs *regs,

					   unsigned long dr6)

{

	bool icebp;



	/*

	 * If something gets miswired and we end up here for a kernel mode

	 * #DB, we will malfunction.
@@ -907,8 +885,30 @@ static __always_inline void exc_debug_user(struct pt_regs *regs, 
	irqentry_enter_from_user_mode(regs);

	instrumentation_begin();



	handle_debug(regs, &dr6);

	/*

	 * If dr6 has no reason to give us about the origin of this trap,

	 * then it's very likely the result of an icebp/int01 trap.

	 * User wants a sigtrap for that.

	 */

	icebp = !dr6;



	if (notify_debug(regs, &dr6))

		goto out;



	/* It's safe to allow irq's after DR6 has been saved */

	local_irq_enable();



	if (v8086_mode(regs)) {

		handle_vm86_trap((struct kernel_vm86_regs *)regs, 0, X86_TRAP_DB);

		goto out_irq;

	}



	if (dr6 & (DR_STEP | DR_TRAP_BITS) || icebp)

		send_sigtrap(regs, 0, get_si_code(dr6));



out_irq:

	local_irq_disable();

out:

	instrumentation_end();

	irqentry_exit_to_user_mode(regs);

}

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