[linux-2.6-block.git] / arch / powerpc / kernel / hw_breakpoint.c

/*
 * HW_breakpoint: a unified kernel/user-space hardware breakpoint facility,
 * using the CPU's debug registers. Derived from
 * "arch/x86/kernel/hw_breakpoint.c"
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 *
 * Copyright 2010 IBM Corporation
 * Author: K.Prasad <prasad@linux.vnet.ibm.com>
 *
 */

#include <linux/hw_breakpoint.h>
#include <linux/notifier.h>
#include <linux/kprobes.h>
#include <linux/percpu.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/smp.h>

#include <asm/hw_breakpoint.h>
#include <asm/processor.h>
#include <asm/sstep.h>
#include <asm/uaccess.h>

/*
 * Stores the breakpoints currently in use on each breakpoint address
 * register for every cpu
 */
static DEFINE_PER_CPU(struct perf_event *, bp_per_reg);

/*
 * Returns total number of data or instruction breakpoints available.
 */
int hw_breakpoint_slots(int type)
{
	if (type == TYPE_DATA)
		return HBP_NUM;
	return 0;		/* no instruction breakpoints available */
}

/*
 * Install a perf counter breakpoint.
 *
 * We seek a free debug address register and use it for this
 * breakpoint.
 *
 * Atomic: we hold the counter->ctx->lock and we only handle variables
 * and registers local to this cpu.
 */
int arch_install_hw_breakpoint(struct perf_event *bp)
{
	struct arch_hw_breakpoint *info = counter_arch_bp(bp);
	struct perf_event **slot = this_cpu_ptr(&bp_per_reg);

	*slot = bp;

	/*
	 * Do not install DABR values if the instruction must be single-stepped.
	 * If so, DABR will be populated in single_step_dabr_instruction().
	 */
	if (current->thread.last_hit_ubp != bp)
		__set_breakpoint(info);

	return 0;
}

/*
 * Uninstall the breakpoint contained in the given counter.
 *
 * First we search the debug address register it uses and then we disable
 * it.
 *
 * Atomic: we hold the counter->ctx->lock and we only handle variables
 * and registers local to this cpu.
 */
void arch_uninstall_hw_breakpoint(struct perf_event *bp)
{
	struct perf_event **slot = this_cpu_ptr(&bp_per_reg);

	if (*slot != bp) {
		WARN_ONCE(1, "Can't find the breakpoint");
		return;
	}

	*slot = NULL;
	hw_breakpoint_disable();
}

/*
 * Perform cleanup of arch-specific counters during unregistration
 * of the perf-event
 */
void arch_unregister_hw_breakpoint(struct perf_event *bp)
{
	/*
	 * If the breakpoint is unregistered between a hw_breakpoint_handler()
	 * and the single_step_dabr_instruction(), then cleanup the breakpoint
	 * restoration variables to prevent dangling pointers.
	 * FIXME, this should not be using bp->ctx at all! Sayeth peterz.
	 */
	if (bp->ctx && bp->ctx->task && bp->ctx->task != ((void *)-1L))
		bp->ctx->task->thread.last_hit_ubp = NULL;
}

/*
 * Check for virtual address in kernel space.
 */
int arch_check_bp_in_kernelspace(struct perf_event *bp)
{
	struct arch_hw_breakpoint *info = counter_arch_bp(bp);

	return is_kernel_addr(info->address);
}

int arch_bp_generic_fields(int type, int *gen_bp_type)
{
	*gen_bp_type = 0;
	if (type & HW_BRK_TYPE_READ)
		*gen_bp_type |= HW_BREAKPOINT_R;
	if (type & HW_BRK_TYPE_WRITE)
		*gen_bp_type |= HW_BREAKPOINT_W;
	if (*gen_bp_type == 0)
		return -EINVAL;
	return 0;
}

/*
 * Validate the arch-specific HW Breakpoint register settings
 */
int arch_validate_hwbkpt_settings(struct perf_event *bp)
{
	int ret = -EINVAL, length_max;
	struct arch_hw_breakpoint *info = counter_arch_bp(bp);

	if (!bp)
		return ret;

	info->type = HW_BRK_TYPE_TRANSLATE;
	if (bp->attr.bp_type & HW_BREAKPOINT_R)
		info->type |= HW_BRK_TYPE_READ;
	if (bp->attr.bp_type & HW_BREAKPOINT_W)
		info->type |= HW_BRK_TYPE_WRITE;
	if (info->type == HW_BRK_TYPE_TRANSLATE)
		/* must set alteast read or write */
		return ret;
	if (!(bp->attr.exclude_user))
		info->type |= HW_BRK_TYPE_USER;
	if (!(bp->attr.exclude_kernel))
		info->type |= HW_BRK_TYPE_KERNEL;
	if (!(bp->attr.exclude_hv))
		info->type |= HW_BRK_TYPE_HYP;
	info->address = bp->attr.bp_addr;
	info->len = bp->attr.bp_len;

	/*
	 * Since breakpoint length can be a maximum of HW_BREAKPOINT_LEN(8)
	 * and breakpoint addresses are aligned to nearest double-word
	 * HW_BREAKPOINT_ALIGN by rounding off to the lower address, the
	 * 'symbolsize' should satisfy the check below.
	 */
	length_max = 8; /* DABR */
	if (cpu_has_feature(CPU_FTR_DAWR)) {
		length_max = 512 ; /* 64 doublewords */
		/* DAWR region can't cross 512 boundary */
		if ((bp->attr.bp_addr >> 10) != 
		    ((bp->attr.bp_addr + bp->attr.bp_len - 1) >> 10))
			return -EINVAL;
	}
	if (info->len >
	    (length_max - (info->address & HW_BREAKPOINT_ALIGN)))
		return -EINVAL;
	return 0;
}

/*
 * Restores the breakpoint on the debug registers.
 * Invoke this function if it is known that the execution context is
 * about to change to cause loss of MSR_SE settings.
 */
void thread_change_pc(struct task_struct *tsk, struct pt_regs *regs)
{
	struct arch_hw_breakpoint *info;

	if (likely(!tsk->thread.last_hit_ubp))
		return;

	info = counter_arch_bp(tsk->thread.last_hit_ubp);
	regs->msr &= ~MSR_SE;
	__set_breakpoint(info);
	tsk->thread.last_hit_ubp = NULL;
}

/*
 * Handle debug exception notifications.
 */
int __kprobes hw_breakpoint_handler(struct die_args *args)
{
	int rc = NOTIFY_STOP;
	struct perf_event *bp;
	struct pt_regs *regs = args->regs;
	int stepped = 1;
	struct arch_hw_breakpoint *info;
	unsigned int instr;
	unsigned long dar = regs->dar;

	/* Disable breakpoints during exception handling */
	hw_breakpoint_disable();

	/*
	 * The counter may be concurrently released but that can only
	 * occur from a call_rcu() path. We can then safely fetch
	 * the breakpoint, use its callback, touch its counter
	 * while we are in an rcu_read_lock() path.
	 */
	rcu_read_lock();

	bp = __this_cpu_read(bp_per_reg);
	if (!bp)
		goto out;
	info = counter_arch_bp(bp);

	/*
	 * Return early after invoking user-callback function without restoring
	 * DABR if the breakpoint is from ptrace which always operates in
	 * one-shot mode. The ptrace-ed process will receive the SIGTRAP signal
	 * generated in do_dabr().
	 */
	if (bp->overflow_handler == ptrace_triggered) {
		perf_bp_event(bp, regs);
		rc = NOTIFY_DONE;
		goto out;
	}

	/*
	 * Verify if dar lies within the address range occupied by the symbol
	 * being watched to filter extraneous exceptions.  If it doesn't,
	 * we still need to single-step the instruction, but we don't
	 * generate an event.
	 */
	info->type &= ~HW_BRK_TYPE_EXTRANEOUS_IRQ;
	if (!((bp->attr.bp_addr <= dar) &&
	      (dar - bp->attr.bp_addr < bp->attr.bp_len)))
		info->type |= HW_BRK_TYPE_EXTRANEOUS_IRQ;

	/* Do not emulate user-space instructions, instead single-step them */
	if (user_mode(regs)) {
		current->thread.last_hit_ubp = bp;
		regs->msr |= MSR_SE;
		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(bp);
		goto out;
	}
	/*
	 * As a policy, the callback is invoked in a 'trigger-after-execute'
	 * fashion
	 */
	if (!(info->type & HW_BRK_TYPE_EXTRANEOUS_IRQ))
		perf_bp_event(bp, regs);

	__set_breakpoint(info);
out:
	rcu_read_unlock();
	return rc;
}

/*
 * Handle single-step exceptions following a DABR hit.
 */
static int __kprobes single_step_dabr_instruction(struct die_args *args)
{
	struct pt_regs *regs = args->regs;
	struct perf_event *bp = NULL;
	struct arch_hw_breakpoint *info;

	bp = current->thread.last_hit_ubp;
	/*
	 * Check if we are single-stepping as a result of a
	 * previous HW Breakpoint exception
	 */
	if (!bp)
		return NOTIFY_DONE;

	info = counter_arch_bp(bp);

	/*
	 * We shall invoke the user-defined callback function in the single
	 * stepping handler to confirm to 'trigger-after-execute' semantics
	 */
	if (!(info->type & HW_BRK_TYPE_EXTRANEOUS_IRQ))
		perf_bp_event(bp, regs);

	__set_breakpoint(info);
	current->thread.last_hit_ubp = NULL;

	/*
	 * If the process was being single-stepped by ptrace, let the
	 * other single-step actions occur (e.g. generate SIGTRAP).
	 */
	if (test_thread_flag(TIF_SINGLESTEP))
		return NOTIFY_DONE;

	return NOTIFY_STOP;
}

/*
 * Handle debug exception notifications.
 */
int __kprobes hw_breakpoint_exceptions_notify(
		struct notifier_block *unused, unsigned long val, void *data)
{
	int ret = NOTIFY_DONE;

	switch (val) {
	case DIE_DABR_MATCH:
		ret = hw_breakpoint_handler(data);
		break;
	case DIE_SSTEP:
		ret = single_step_dabr_instruction(data);
		break;
	}

	return ret;
}

/*
 * Release the user breakpoints used by ptrace
 */
void flush_ptrace_hw_breakpoint(struct task_struct *tsk)
{
	struct thread_struct *t = &tsk->thread;

	unregister_hw_breakpoint(t->ptrace_bps[0]);
	t->ptrace_bps[0] = NULL;
}

void hw_breakpoint_pmu_read(struct perf_event *bp)
{
	/* TODO */
}
Commit	Line	Data
5aae8a53 P	1	/*
	2	* HW_breakpoint: a unified kernel/user-space hardware breakpoint facility,
	3	* using the CPU's debug registers. Derived from
	4	* "arch/x86/kernel/hw_breakpoint.c"
	5	*
	6	* This program is free software; you can redistribute it and/or modify
	7	* it under the terms of the GNU General Public License as published by
	8	* the Free Software Foundation; either version 2 of the License, or
	9	* (at your option) any later version.
	10	*
	11	* This program is distributed in the hope that it will be useful,
	12	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	13	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	14	* GNU General Public License for more details.
	15	*
	16	* You should have received a copy of the GNU General Public License
	17	* along with this program; if not, write to the Free Software
	18	* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
	19	*
	20	* Copyright 2010 IBM Corporation
	21	* Author: K.Prasad <prasad@linux.vnet.ibm.com>
	22	*
	23	*/
	24
	25	#include <linux/hw_breakpoint.h>
	26	#include <linux/notifier.h>
	27	#include <linux/kprobes.h>
	28	#include <linux/percpu.h>
	29	#include <linux/kernel.h>
5aae8a53	30	#include <linux/sched.h>
5aae8a53 P	31	#include <linux/smp.h>
	32
	33	#include <asm/hw_breakpoint.h>
	34	#include <asm/processor.h>
	35	#include <asm/sstep.h>
	36	#include <asm/uaccess.h>
	37
	38	/*
	39	* Stores the breakpoints currently in use on each breakpoint address
	40	* register for every cpu
	41	*/
	42	static DEFINE_PER_CPU(struct perf_event *, bp_per_reg);
	43
d09ec738 PM	44	/*
	45	* Returns total number of data or instruction breakpoints available.
	46	*/
	47	int hw_breakpoint_slots(int type)
	48	{
	49	if (type == TYPE_DATA)
	50	return HBP_NUM;
	51	return 0; /* no instruction breakpoints available */
	52	}
	53
5aae8a53 P	54	/*
	55	* Install a perf counter breakpoint.
	56	*
	57	* We seek a free debug address register and use it for this
	58	* breakpoint.
	59	*
	60	* Atomic: we hold the counter->ctx->lock and we only handle variables
	61	* and registers local to this cpu.
	62	*/
	63	int arch_install_hw_breakpoint(struct perf_event *bp)
	64	{
	65	struct arch_hw_breakpoint *info = counter_arch_bp(bp);
69111bac	66	struct perf_event **slot = this_cpu_ptr(&bp_per_reg);
5aae8a53 P	67
	68	*slot = bp;
	69
	70	/*
	71	* Do not install DABR values if the instruction must be single-stepped.
	72	* If so, DABR will be populated in single_step_dabr_instruction().
	73	*/
	74	if (current->thread.last_hit_ubp != bp)
21f58507	75	__set_breakpoint(info);
5aae8a53 P	76
	77	return 0;
	78	}
	79
	80	/*
	81	* Uninstall the breakpoint contained in the given counter.
	82	*
	83	* First we search the debug address register it uses and then we disable
	84	* it.
	85	*
	86	* Atomic: we hold the counter->ctx->lock and we only handle variables
	87	* and registers local to this cpu.
	88	*/
	89	void arch_uninstall_hw_breakpoint(struct perf_event *bp)
	90	{
69111bac	91	struct perf_event **slot = this_cpu_ptr(&bp_per_reg);
5aae8a53 P	92
	93	if (*slot != bp) {
	94	WARN_ONCE(1, "Can't find the breakpoint");
	95	return;
	96	}
	97
	98	*slot = NULL;
9422de3e	99	hw_breakpoint_disable();
5aae8a53 P	100	}
	101
	102	/*
	103	* Perform cleanup of arch-specific counters during unregistration
	104	* of the perf-event
	105	*/
	106	void arch_unregister_hw_breakpoint(struct perf_event *bp)
	107	{
	108	/*
	109	* If the breakpoint is unregistered between a hw_breakpoint_handler()
	110	* and the single_step_dabr_instruction(), then cleanup the breakpoint
	111	* restoration variables to prevent dangling pointers.
fb822e60	112	* FIXME, this should not be using bp->ctx at all! Sayeth peterz.
5aae8a53	113	*/
fb822e60	114	if (bp->ctx && bp->ctx->task && bp->ctx->task != ((void *)-1L))
5aae8a53 P	115	bp->ctx->task->thread.last_hit_ubp = NULL;
	116	}
	117
	118	/*
	119	* Check for virtual address in kernel space.
	120	*/
	121	int arch_check_bp_in_kernelspace(struct perf_event *bp)
	122	{
	123	struct arch_hw_breakpoint *info = counter_arch_bp(bp);
	124
	125	return is_kernel_addr(info->address);
	126	}
	127
	128	int arch_bp_generic_fields(int type, int *gen_bp_type)
	129	{
9422de3e MN	130	*gen_bp_type = 0;
	131	if (type & HW_BRK_TYPE_READ)
	132	*gen_bp_type \|= HW_BREAKPOINT_R;
	133	if (type & HW_BRK_TYPE_WRITE)
	134	*gen_bp_type \|= HW_BREAKPOINT_W;
	135	if (*gen_bp_type == 0)
5aae8a53	136	return -EINVAL;
5aae8a53 P	137	return 0;
	138	}
	139
	140	/*
	141	* Validate the arch-specific HW Breakpoint register settings
	142	*/
	143	int arch_validate_hwbkpt_settings(struct perf_event *bp)
	144	{
4ae7ebe9	145	int ret = -EINVAL, length_max;
5aae8a53 P	146	struct arch_hw_breakpoint *info = counter_arch_bp(bp);
	147
	148	if (!bp)
	149	return ret;
	150
9422de3e MN	151	info->type = HW_BRK_TYPE_TRANSLATE;
	152	if (bp->attr.bp_type & HW_BREAKPOINT_R)
	153	info->type \|= HW_BRK_TYPE_READ;
	154	if (bp->attr.bp_type & HW_BREAKPOINT_W)
	155	info->type \|= HW_BRK_TYPE_WRITE;
	156	if (info->type == HW_BRK_TYPE_TRANSLATE)
	157	/* must set alteast read or write */
5aae8a53	158	return ret;
9422de3e MN	159	if (!(bp->attr.exclude_user))
	160	info->type \|= HW_BRK_TYPE_USER;
	161	if (!(bp->attr.exclude_kernel))
	162	info->type \|= HW_BRK_TYPE_KERNEL;
	163	if (!(bp->attr.exclude_hv))
	164	info->type \|= HW_BRK_TYPE_HYP;
5aae8a53 P	165	info->address = bp->attr.bp_addr;
	166	info->len = bp->attr.bp_len;
	167
	168	/*
	169	* Since breakpoint length can be a maximum of HW_BREAKPOINT_LEN(8)
	170	* and breakpoint addresses are aligned to nearest double-word
	171	* HW_BREAKPOINT_ALIGN by rounding off to the lower address, the
	172	* 'symbolsize' should satisfy the check below.
	173	*/
4ae7ebe9 MN	174	length_max = 8; /* DABR */
	175	if (cpu_has_feature(CPU_FTR_DAWR)) {
	176	length_max = 512 ; /* 64 doublewords */
	177	/* DAWR region can't cross 512 boundary */
	178	if ((bp->attr.bp_addr >> 10) !=
e2a800be	179	((bp->attr.bp_addr + bp->attr.bp_len - 1) >> 10))
4ae7ebe9 MN	180	return -EINVAL;
4ae7ebe9 MN	181	}
5aae8a53	182	if (info->len >
4ae7ebe9	183	(length_max - (info->address & HW_BREAKPOINT_ALIGN)))
5aae8a53 P	184	return -EINVAL;
	185	return 0;
	186	}
	187
06532a67 P	188	/*
	189	* Restores the breakpoint on the debug registers.
	190	* Invoke this function if it is known that the execution context is
	191	* about to change to cause loss of MSR_SE settings.
	192	*/
	193	void thread_change_pc(struct task_struct tsk, struct pt_regs regs)
	194	{
	195	struct arch_hw_breakpoint *info;
	196
	197	if (likely(!tsk->thread.last_hit_ubp))
	198	return;
	199
	200	info = counter_arch_bp(tsk->thread.last_hit_ubp);
	201	regs->msr &= ~MSR_SE;
21f58507	202	__set_breakpoint(info);
06532a67 P	203	tsk->thread.last_hit_ubp = NULL;
	204	}
	205
5aae8a53 P	206	/*
	207	* Handle debug exception notifications.
	208	*/
	209	int __kprobes hw_breakpoint_handler(struct die_args *args)
	210	{
5aae8a53 P	211	int rc = NOTIFY_STOP;
	212	struct perf_event *bp;
	213	struct pt_regs *regs = args->regs;
	214	int stepped = 1;
	215	struct arch_hw_breakpoint *info;
	216	unsigned int instr;
e3e94084	217	unsigned long dar = regs->dar;
5aae8a53 P	218
5aae8a53 P	219	/* Disable breakpoints during exception handling */
9422de3e	220	hw_breakpoint_disable();
574cb248	221
5aae8a53 P	222	/*
	223	* The counter may be concurrently released but that can only
	224	* occur from a call_rcu() path. We can then safely fetch
	225	* the breakpoint, use its callback, touch its counter
	226	* while we are in an rcu_read_lock() path.
	227	*/
	228	rcu_read_lock();
	229
69111bac	230	bp = __this_cpu_read(bp_per_reg);
5aae8a53 P	231	if (!bp)
	232	goto out;
	233	info = counter_arch_bp(bp);
5aae8a53 P	234
	235	/*
	236	* Return early after invoking user-callback function without restoring
	237	* DABR if the breakpoint is from ptrace which always operates in
	238	* one-shot mode. The ptrace-ed process will receive the SIGTRAP signal
	239	* generated in do_dabr().
	240	*/
574cb248	241	if (bp->overflow_handler == ptrace_triggered) {
5aae8a53 P	242	perf_bp_event(bp, regs);
	243	rc = NOTIFY_DONE;
	244	goto out;
	245	}
	246
e3e94084 P	247	/*
e3e94084 P	248	* Verify if dar lies within the address range occupied by the symbol
574cb248 PM	249	* being watched to filter extraneous exceptions. If it doesn't,
	250	* we still need to single-step the instruction, but we don't
	251	* generate an event.
e3e94084	252	*/
540e07c6	253	info->type &= ~HW_BRK_TYPE_EXTRANEOUS_IRQ;
9422de3e MN	254	if (!((bp->attr.bp_addr <= dar) &&
	255	(dar - bp->attr.bp_addr < bp->attr.bp_len)))
	256	info->type \|= HW_BRK_TYPE_EXTRANEOUS_IRQ;
e3e94084	257
5aae8a53 P	258	/* Do not emulate user-space instructions, instead single-step them */
5aae8a53 P	259	if (user_mode(regs)) {
6d9c00c6	260	current->thread.last_hit_ubp = bp;
5aae8a53 P	261	regs->msr \|= MSR_SE;
	262	goto out;
	263	}
	264
	265	stepped = 0;
	266	instr = 0;
	267	if (!__get_user_inatomic(instr, (unsigned int *) regs->nip))
	268	stepped = emulate_step(regs, instr);
	269
	270	/*
	271	* emulate_step() could not execute it. We've failed in reliably
	272	* handling the hw-breakpoint. Unregister it and throw a warning
	273	* message to let the user know about it.
	274	*/
	275	if (!stepped) {
	276	WARN(1, "Unable to handle hardware breakpoint. Breakpoint at "
	277	"0x%lx will be disabled.", info->address);
	278	perf_event_disable(bp);
	279	goto out;
	280	}
	281	/*
	282	* As a policy, the callback is invoked in a 'trigger-after-execute'
	283	* fashion
	284	*/
9422de3e	285	if (!(info->type & HW_BRK_TYPE_EXTRANEOUS_IRQ))
e3e94084	286	perf_bp_event(bp, regs);
5aae8a53	287
21f58507	288	__set_breakpoint(info);
5aae8a53 P	289	out:
	290	rcu_read_unlock();
	291	return rc;
	292	}
	293
	294	/*
	295	* Handle single-step exceptions following a DABR hit.
	296	*/
e51df2c1	297	static int __kprobes single_step_dabr_instruction(struct die_args *args)
5aae8a53 P	298	{
	299	struct pt_regs *regs = args->regs;
	300	struct perf_event *bp = NULL;
3f4693ee	301	struct arch_hw_breakpoint *info;
5aae8a53 P	302
	303	bp = current->thread.last_hit_ubp;
	304	/*
	305	* Check if we are single-stepping as a result of a
	306	* previous HW Breakpoint exception
	307	*/
	308	if (!bp)
	309	return NOTIFY_DONE;
	310
3f4693ee	311	info = counter_arch_bp(bp);
5aae8a53 P	312
	313	/*
	314	* We shall invoke the user-defined callback function in the single
	315	* stepping handler to confirm to 'trigger-after-execute' semantics
	316	*/
9422de3e	317	if (!(info->type & HW_BRK_TYPE_EXTRANEOUS_IRQ))
e3e94084	318	perf_bp_event(bp, regs);
5aae8a53	319
21f58507	320	__set_breakpoint(info);
76b0f133 PM	321	current->thread.last_hit_ubp = NULL;
76b0f133 PM	322
5aae8a53	323	/*
76b0f133 PM	324	* If the process was being single-stepped by ptrace, let the
76b0f133 PM	325	* other single-step actions occur (e.g. generate SIGTRAP).
5aae8a53	326	*/
76b0f133 PM	327	if (test_thread_flag(TIF_SINGLESTEP))
76b0f133 PM	328	return NOTIFY_DONE;
5aae8a53	329
5aae8a53 P	330	return NOTIFY_STOP;
	331	}
	332
	333	/*
	334	* Handle debug exception notifications.
	335	*/
	336	int __kprobes hw_breakpoint_exceptions_notify(
	337	struct notifier_block unused, unsigned long val, void data)
	338	{
	339	int ret = NOTIFY_DONE;
	340
	341	switch (val) {
	342	case DIE_DABR_MATCH:
	343	ret = hw_breakpoint_handler(data);
	344	break;
	345	case DIE_SSTEP:
	346	ret = single_step_dabr_instruction(data);
	347	break;
	348	}
	349
	350	return ret;
	351	}
	352
	353	/*
	354	* Release the user breakpoints used by ptrace
	355	*/
	356	void flush_ptrace_hw_breakpoint(struct task_struct *tsk)
	357	{
	358	struct thread_struct *t = &tsk->thread;
	359
	360	unregister_hw_breakpoint(t->ptrace_bps[0]);
	361	t->ptrace_bps[0] = NULL;
	362	}
	363
	364	void hw_breakpoint_pmu_read(struct perf_event *bp)
	365	{
	366	/* TODO */
	367	}