Commit 658d029d authored by Christophe Leroy's avatar Christophe Leroy Committed by Michael Ellerman
Browse files

powerpc/hw_breakpoint: move instruction stepping out of hw_breakpoint_handler() 



On 8xx, breakpoints stop after executing the instruction, so
stepping/emulation is not needed. Move it into a sub-function and
remove the #ifdefs.

Signed-off-by: default avatarChristophe Leroy <christophe.leroy@c-s.fr>
Reviewed-by: default avatarRavi Bangoria <ravi.bangoria@linux.ibm.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/f8cdc3f1c66ad3c43ebc568abcc6c39ed4676284.1561737231.git.christophe.leroy@c-s.fr
parent 65e701b2

arch/powerpc/kernel/hw_breakpoint.c

+33 −27
Original line number Diff line number Diff line
@@ -198,15 +198,43 @@ void thread_change_pc(struct task_struct *tsk, struct pt_regs *regs) 
/*

 * Handle debug exception notifications.

 */

static bool stepping_handler(struct pt_regs *regs, struct perf_event *bp,

			     unsigned long addr)

{

	int stepped;

	unsigned int instr;



	/* Do not emulate user-space instructions, instead single-step them */

	if (user_mode(regs)) {

		current->thread.last_hit_ubp = bp;

		regs->msr |= MSR_SE;

		return false;

	}



	stepped = 0;

	instr = 0;

	if (!__get_user_inatomic(instr, (unsigned int *)regs->nip))

		stepped = emulate_step(regs, instr);



	/*

	 * emulate_step() could not execute it. We've failed in reliably

	 * handling the hw-breakpoint. Unregister it and throw a warning

	 * message to let the user know about it.

	 */

	if (!stepped) {

		WARN(1, "Unable to handle hardware breakpoint. Breakpoint at "

			"0x%lx will be disabled.", addr);

		perf_event_disable_inatomic(bp);

		return false;

	}

	return true;

}



int hw_breakpoint_handler(struct die_args *args)

{

	int rc = NOTIFY_STOP;

	struct perf_event *bp;

	struct pt_regs *regs = args->regs;

#ifndef CONFIG_PPC_8xx

	int stepped = 1;

	unsigned int instr;

#endif

	struct arch_hw_breakpoint *info;

	unsigned long dar = regs->dar;
@@ -251,31 +279,9 @@ int hw_breakpoint_handler(struct die_args *args) 
	      (dar - bp->attr.bp_addr < bp->attr.bp_len)))

		info->type |= HW_BRK_TYPE_EXTRANEOUS_IRQ;



#ifndef CONFIG_PPC_8xx

	/* Do not emulate user-space instructions, instead single-step them */

	if (user_mode(regs)) {

		current->thread.last_hit_ubp = bp;

		regs->msr |= MSR_SE;

	if (!IS_ENABLED(CONFIG_PPC_8xx) && !stepping_handler(regs, bp, info->address))

		goto out;

	}



	stepped = 0;

	instr = 0;

	if (!__get_user_inatomic(instr, (unsigned int *) regs->nip))

		stepped = emulate_step(regs, instr);



	/*

	 * emulate_step() could not execute it. We've failed in reliably

	 * handling the hw-breakpoint. Unregister it and throw a warning

	 * message to let the user know about it.

	 */

	if (!stepped) {

		WARN(1, "Unable to handle hardware breakpoint. Breakpoint at "

			"0x%lx will be disabled.", info->address);

		perf_event_disable_inatomic(bp);

		goto out;

	}

#endif

	/*

	 * As a policy, the callback is invoked in a 'trigger-after-execute'

	 * fashion

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