[mirror_ubuntu-jammy-kernel.git] / 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 (C) 2007 Alan Stern
 * Copyright (C) 2009 IBM Corporation
 * Copyright (C) 2009 Frederic Weisbecker <fweisbec@gmail.com>
 */

/*
 * HW_breakpoint: a unified kernel/user-space hardware breakpoint facility,
 * using the CPU's debug registers.
 */

#include <linux/perf_event.h>
#include <linux/hw_breakpoint.h>
#include <linux/irqflags.h>
#include <linux/notifier.h>
#include <linux/kallsyms.h>
#include <linux/kprobes.h>
#include <linux/percpu.h>
#include <linux/kdebug.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/init.h>
#include <linux/smp.h>

#include <asm/hw_breakpoint.h>
#include <asm/processor.h>
#include <asm/debugreg.h>

/* Per cpu debug control register value */
DEFINE_PER_CPU(unsigned long, dr7);

/* Per cpu debug address registers values */
static DEFINE_PER_CPU(unsigned long, cpu_debugreg[HBP_NUM]);

/*
 * Stores the breakpoints currently in use on each breakpoint address
 * register for each cpus
 */
static DEFINE_PER_CPU(struct perf_event *, bp_per_reg[HBP_NUM]);


/*
 * Encode the length, type, Exact, and Enable bits for a particular breakpoint
 * as stored in debug register 7.
 */
unsigned long encode_dr7(int drnum, unsigned int len, unsigned int type)
{
	unsigned long bp_info;

	bp_info = (len | type) & 0xf;
	bp_info <<= (DR_CONTROL_SHIFT + drnum * DR_CONTROL_SIZE);
	bp_info |= (DR_GLOBAL_ENABLE << (drnum * DR_ENABLE_SIZE)) |
				DR_GLOBAL_SLOWDOWN;
	return bp_info;
}

/*
 * Decode the length and type bits for a particular breakpoint as
 * stored in debug register 7.  Return the "enabled" status.
 */
int decode_dr7(unsigned long dr7, int bpnum, unsigned *len, unsigned *type)
{
	int bp_info = dr7 >> (DR_CONTROL_SHIFT + bpnum * DR_CONTROL_SIZE);

	*len = (bp_info & 0xc) | 0x40;
	*type = (bp_info & 0x3) | 0x80;

	return (dr7 >> (bpnum * DR_ENABLE_SIZE)) & 0x3;
}

/*
 * Install a perf counter breakpoint.
 *
 * We seek a free debug address register and use it for this
 * breakpoint. Eventually we enable it in the debug control register.
 *
 * 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);
	unsigned long *dr7;
	int i;

	for (i = 0; i < HBP_NUM; i++) {
		struct perf_event **slot = &__get_cpu_var(bp_per_reg[i]);

		if (!*slot) {
			*slot = bp;
			break;
		}
	}

	if (WARN_ONCE(i == HBP_NUM, "Can't find any breakpoint slot"))
		return -EBUSY;

	set_debugreg(info->address, i);
	__get_cpu_var(cpu_debugreg[i]) = info->address;

	dr7 = &__get_cpu_var(dr7);
	*dr7 |= encode_dr7(i, info->len, info->type);

	set_debugreg(*dr7, 7);

	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 arch_hw_breakpoint *info = counter_arch_bp(bp);
	unsigned long *dr7;
	int i;

	for (i = 0; i < HBP_NUM; i++) {
		struct perf_event **slot = &__get_cpu_var(bp_per_reg[i]);

		if (*slot == bp) {
			*slot = NULL;
			break;
		}
	}

	if (WARN_ONCE(i == HBP_NUM, "Can't find any breakpoint slot"))
		return;

	dr7 = &__get_cpu_var(dr7);
	*dr7 &= ~encode_dr7(i, info->len, info->type);

	set_debugreg(*dr7, 7);
}

static int get_hbp_len(u8 hbp_len)
{
	unsigned int len_in_bytes = 0;

	switch (hbp_len) {
	case X86_BREAKPOINT_LEN_1:
		len_in_bytes = 1;
		break;
	case X86_BREAKPOINT_LEN_2:
		len_in_bytes = 2;
		break;
	case X86_BREAKPOINT_LEN_4:
		len_in_bytes = 4;
		break;
#ifdef CONFIG_X86_64
	case X86_BREAKPOINT_LEN_8:
		len_in_bytes = 8;
		break;
#endif
	}
	return len_in_bytes;
}

/*
 * Check for virtual address in user space.
 */
int arch_check_va_in_userspace(unsigned long va, u8 hbp_len)
{
	unsigned int len;

	len = get_hbp_len(hbp_len);

	return (va <= TASK_SIZE - len);
}

/*
 * Check for virtual address in kernel space.
 */
static int arch_check_va_in_kernelspace(unsigned long va, u8 hbp_len)
{
	unsigned int len;

	len = get_hbp_len(hbp_len);

	return (va >= TASK_SIZE) && ((va + len - 1) >= TASK_SIZE);
}

/*
 * Store a breakpoint's encoded address, length, and type.
 */
static int arch_store_info(struct perf_event *bp)
{
	struct arch_hw_breakpoint *info = counter_arch_bp(bp);
	/*
	 * For kernel-addresses, either the address or symbol name can be
	 * specified.
	 */
	if (info->name)
		info->address = (unsigned long)
				kallsyms_lookup_name(info->name);
	if (info->address)
		return 0;

	return -EINVAL;
}

int arch_bp_generic_fields(int x86_len, int x86_type,
			   int *gen_len, int *gen_type)
{
	/* Len */
	switch (x86_len) {
	case X86_BREAKPOINT_LEN_1:
		*gen_len = HW_BREAKPOINT_LEN_1;
		break;
	case X86_BREAKPOINT_LEN_2:
		*gen_len = HW_BREAKPOINT_LEN_2;
		break;
	case X86_BREAKPOINT_LEN_4:
		*gen_len = HW_BREAKPOINT_LEN_4;
		break;
#ifdef CONFIG_X86_64
	case X86_BREAKPOINT_LEN_8:
		*gen_len = HW_BREAKPOINT_LEN_8;
		break;
#endif
	default:
		return -EINVAL;
	}

	/* Type */
	switch (x86_type) {
	case X86_BREAKPOINT_EXECUTE:
		*gen_type = HW_BREAKPOINT_X;
		break;
	case X86_BREAKPOINT_WRITE:
		*gen_type = HW_BREAKPOINT_W;
		break;
	case X86_BREAKPOINT_RW:
		*gen_type = HW_BREAKPOINT_W | HW_BREAKPOINT_R;
		break;
	default:
		return -EINVAL;
	}

	return 0;
}


static int arch_build_bp_info(struct perf_event *bp)
{
	struct arch_hw_breakpoint *info = counter_arch_bp(bp);

	info->address = bp->attr.bp_addr;

	/* Len */
	switch (bp->attr.bp_len) {
	case HW_BREAKPOINT_LEN_1:
		info->len = X86_BREAKPOINT_LEN_1;
		break;
	case HW_BREAKPOINT_LEN_2:
		info->len = X86_BREAKPOINT_LEN_2;
		break;
	case HW_BREAKPOINT_LEN_4:
		info->len = X86_BREAKPOINT_LEN_4;
		break;
#ifdef CONFIG_X86_64
	case HW_BREAKPOINT_LEN_8:
		info->len = X86_BREAKPOINT_LEN_8;
		break;
#endif
	default:
		return -EINVAL;
	}

	/* Type */
	switch (bp->attr.bp_type) {
	case HW_BREAKPOINT_W:
		info->type = X86_BREAKPOINT_WRITE;
		break;
	case HW_BREAKPOINT_W | HW_BREAKPOINT_R:
		info->type = X86_BREAKPOINT_RW;
		break;
	case HW_BREAKPOINT_X:
		info->type = X86_BREAKPOINT_EXECUTE;
		break;
	default:
		return -EINVAL;
	}

	return 0;
}
/*
 * Validate the arch-specific HW Breakpoint register settings
 */
int arch_validate_hwbkpt_settings(struct perf_event *bp,
				  struct task_struct *tsk)
{
	struct arch_hw_breakpoint *info = counter_arch_bp(bp);
	unsigned int align;
	int ret;


	ret = arch_build_bp_info(bp);
	if (ret)
		return ret;

	ret = -EINVAL;

	if (info->type == X86_BREAKPOINT_EXECUTE)
		/*
		 * Ptrace-refactoring code
		 * For now, we'll allow instruction breakpoint only for user-space
		 * addresses
		 */
		if ((!arch_check_va_in_userspace(info->address, info->len)) &&
			info->len != X86_BREAKPOINT_EXECUTE)
			return ret;

	switch (info->len) {
	case X86_BREAKPOINT_LEN_1:
		align = 0;
		break;
	case X86_BREAKPOINT_LEN_2:
		align = 1;
		break;
	case X86_BREAKPOINT_LEN_4:
		align = 3;
		break;
#ifdef CONFIG_X86_64
	case X86_BREAKPOINT_LEN_8:
		align = 7;
		break;
#endif
	default:
		return ret;
	}

	if (bp->callback)
		ret = arch_store_info(bp);

	if (ret < 0)
		return ret;
	/*
	 * Check that the low-order bits of the address are appropriate
	 * for the alignment implied by len.
	 */
	if (info->address & align)
		return -EINVAL;

	/* Check that the virtual address is in the proper range */
	if (tsk) {
		if (!arch_check_va_in_userspace(info->address, info->len))
			return -EFAULT;
	} else {
		if (!arch_check_va_in_kernelspace(info->address, info->len))
			return -EFAULT;
	}

	return 0;
}

/*
 * Dump the debug register contents to the user.
 * We can't dump our per cpu values because it
 * may contain cpu wide breakpoint, something that
 * doesn't belong to the current task.
 *
 * TODO: include non-ptrace user breakpoints (perf)
 */
void aout_dump_debugregs(struct user *dump)
{
	int i;
	int dr7 = 0;
	struct perf_event *bp;
	struct arch_hw_breakpoint *info;
	struct thread_struct *thread = &current->thread;

	for (i = 0; i < HBP_NUM; i++) {
		bp = thread->ptrace_bps[i];

		if (bp && !bp->attr.disabled) {
			dump->u_debugreg[i] = bp->attr.bp_addr;
			info = counter_arch_bp(bp);
			dr7 |= encode_dr7(i, info->len, info->type);
		} else {
			dump->u_debugreg[i] = 0;
		}
	}

	dump->u_debugreg[4] = 0;
	dump->u_debugreg[5] = 0;
	dump->u_debugreg[6] = current->thread.debugreg6;

	dump->u_debugreg[7] = dr7;
}

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

	for (i = 0; i < HBP_NUM; i++) {
		unregister_hw_breakpoint(t->ptrace_bps[i]);
		t->ptrace_bps[i] = NULL;
	}
}

#ifdef CONFIG_KVM
void hw_breakpoint_restore(void)
{
	set_debugreg(__get_cpu_var(cpu_debugreg[0]), 0);
	set_debugreg(__get_cpu_var(cpu_debugreg[1]), 1);
	set_debugreg(__get_cpu_var(cpu_debugreg[2]), 2);
	set_debugreg(__get_cpu_var(cpu_debugreg[3]), 3);
	set_debugreg(current->thread.debugreg6, 6);
	set_debugreg(__get_cpu_var(dr7), 7);
}
EXPORT_SYMBOL_GPL(hw_breakpoint_restore);
#endif

/*
 * Handle debug exception notifications.
 *
 * Return value is either NOTIFY_STOP or NOTIFY_DONE as explained below.
 *
 * NOTIFY_DONE returned if one of the following conditions is true.
 * i) When the causative address is from user-space and the exception
 * is a valid one, i.e. not triggered as a result of lazy debug register
 * switching
 * ii) When there are more bits than trap<n> set in DR6 register (such
 * as BD, BS or BT) indicating that more than one debug condition is
 * met and requires some more action in do_debug().
 *
 * NOTIFY_STOP returned for all other cases
 *
 */
static int __kprobes hw_breakpoint_handler(struct die_args *args)
{
	int i, cpu, rc = NOTIFY_STOP;
	struct perf_event *bp;
	unsigned long dr7, dr6;
	unsigned long *dr6_p;

	/* The DR6 value is pointed by args->err */
	dr6_p = (unsigned long *)ERR_PTR(args->err);
	dr6 = *dr6_p;

	/* Do an early return if no trap bits are set in DR6 */
	if ((dr6 & DR_TRAP_BITS) == 0)
		return NOTIFY_DONE;

	get_debugreg(dr7, 7);
	/* Disable breakpoints during exception handling */
	set_debugreg(0UL, 7);
	/*
	 * Assert that local interrupts are disabled
	 * Reset the DRn bits in the virtualized register value.
	 * The ptrace trigger routine will add in whatever is needed.
	 */
	current->thread.debugreg6 &= ~DR_TRAP_BITS;
	cpu = get_cpu();

	/* Handle all the breakpoints that were triggered */
	for (i = 0; i < HBP_NUM; ++i) {
		if (likely(!(dr6 & (DR_TRAP0 << i))))
			continue;

		/*
		 * 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 = per_cpu(bp_per_reg[i], cpu);
		if (bp)
			rc = NOTIFY_DONE;
		/*
		 * Reset the 'i'th TRAP bit in dr6 to denote completion of
		 * exception handling
		 */
		(*dr6_p) &= ~(DR_TRAP0 << i);
		/*
		 * bp can be NULL due to lazy debug register switching
		 * or due to concurrent perf counter removing.
		 */
		if (!bp) {
			rcu_read_unlock();
			break;
		}

		(bp->callback)(bp, args->regs);

		rcu_read_unlock();
	}
	if (dr6 & (~DR_TRAP_BITS))
		rc = NOTIFY_DONE;

	set_debugreg(dr7, 7);
	put_cpu();

	return rc;
}

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

	return hw_breakpoint_handler(data);
}

void hw_breakpoint_pmu_read(struct perf_event *bp)
{
	/* TODO */
}

void hw_breakpoint_pmu_unthrottle(struct perf_event *bp)
{
	/* TODO */
}
Commit	Line	Data
0067f129 P	1	/*
	2	* This program is free software; you can redistribute it and/or modify
	3	* it under the terms of the GNU General Public License as published by
	4	* the Free Software Foundation; either version 2 of the License, or
	5	* (at your option) any later version.
	6	*
	7	* This program is distributed in the hope that it will be useful,
	8	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	9	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	10	* GNU General Public License for more details.
	11	*
	12	* You should have received a copy of the GNU General Public License
	13	* along with this program; if not, write to the Free Software
	14	* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
	15	*
	16	* Copyright (C) 2007 Alan Stern
	17	* Copyright (C) 2009 IBM Corporation
24f1e32c	18	* Copyright (C) 2009 Frederic Weisbecker <fweisbec@gmail.com>
0067f129 P	19	*/
	20
	21	/*
	22	* HW_breakpoint: a unified kernel/user-space hardware breakpoint facility,
	23	* using the CPU's debug registers.
	24	*/
	25
24f1e32c FW	26	#include <linux/perf_event.h>
24f1e32c FW	27	#include <linux/hw_breakpoint.h>
0067f129 P	28	#include <linux/irqflags.h>
	29	#include <linux/notifier.h>
	30	#include <linux/kallsyms.h>
	31	#include <linux/kprobes.h>
	32	#include <linux/percpu.h>
	33	#include <linux/kdebug.h>
	34	#include <linux/kernel.h>
	35	#include <linux/module.h>
	36	#include <linux/sched.h>
	37	#include <linux/init.h>
	38	#include <linux/smp.h>
	39
	40	#include <asm/hw_breakpoint.h>
	41	#include <asm/processor.h>
	42	#include <asm/debugreg.h>
	43
24f1e32c FW	44	/* Per cpu debug control register value */
	45	DEFINE_PER_CPU(unsigned long, dr7);
	46
	47	/* Per cpu debug address registers values */
	48	static DEFINE_PER_CPU(unsigned long, cpu_debugreg[HBP_NUM]);
0067f129 P	49
0067f129 P	50	/*
24f1e32c FW	51	* Stores the breakpoints currently in use on each breakpoint address
24f1e32c FW	52	* register for each cpus
0067f129	53	*/
24f1e32c	54	static DEFINE_PER_CPU(struct perf_event *, bp_per_reg[HBP_NUM]);
0067f129 P	55
	56
	57	/*
	58	* Encode the length, type, Exact, and Enable bits for a particular breakpoint
	59	* as stored in debug register 7.
	60	*/
24f1e32c	61	unsigned long encode_dr7(int drnum, unsigned int len, unsigned int type)
0067f129 P	62	{
	63	unsigned long bp_info;
	64
	65	bp_info = (len \| type) & 0xf;
	66	bp_info <<= (DR_CONTROL_SHIFT + drnum * DR_CONTROL_SIZE);
	67	bp_info \|= (DR_GLOBAL_ENABLE << (drnum * DR_ENABLE_SIZE)) \|
	68	DR_GLOBAL_SLOWDOWN;
	69	return bp_info;
	70	}
	71
24f1e32c FW	72	/*
	73	* Decode the length and type bits for a particular breakpoint as
	74	* stored in debug register 7. Return the "enabled" status.
	75	*/
	76	int decode_dr7(unsigned long dr7, int bpnum, unsigned len, unsigned type)
0067f129	77	{
24f1e32c	78	int bp_info = dr7 >> (DR_CONTROL_SHIFT + bpnum * DR_CONTROL_SIZE);
0067f129	79
24f1e32c FW	80	*len = (bp_info & 0xc) \| 0x40;
24f1e32c FW	81	*type = (bp_info & 0x3) \| 0x80;
0067f129	82
24f1e32c	83	return (dr7 >> (bpnum * DR_ENABLE_SIZE)) & 0x3;
0067f129 P	84	}
	85
	86	/*
24f1e32c FW	87	* Install a perf counter breakpoint.
	88	*
	89	* We seek a free debug address register and use it for this
	90	* breakpoint. Eventually we enable it in the debug control register.
	91	*
	92	* Atomic: we hold the counter->ctx->lock and we only handle variables
	93	* and registers local to this cpu.
0067f129	94	*/
24f1e32c	95	int arch_install_hw_breakpoint(struct perf_event *bp)
0067f129	96	{
24f1e32c FW	97	struct arch_hw_breakpoint *info = counter_arch_bp(bp);
	98	unsigned long *dr7;
	99	int i;
	100
	101	for (i = 0; i < HBP_NUM; i++) {
	102	struct perf_event **slot = &__get_cpu_var(bp_per_reg[i]);
	103
	104	if (!*slot) {
	105	*slot = bp;
	106	break;
	107	}
0067f129 P	108	}
0067f129 P	109
24f1e32c FW	110	if (WARN_ONCE(i == HBP_NUM, "Can't find any breakpoint slot"))
	111	return -EBUSY;
	112
	113	set_debugreg(info->address, i);
	114	__get_cpu_var(cpu_debugreg[i]) = info->address;
	115
	116	dr7 = &__get_cpu_var(dr7);
	117	*dr7 \|= encode_dr7(i, info->len, info->type);
	118
	119	set_debugreg(*dr7, 7);
	120
	121	return 0;
0067f129 P	122	}
	123
	124	/*
24f1e32c FW	125	* Uninstall the breakpoint contained in the given counter.
	126	*
	127	* First we search the debug address register it uses and then we disable
	128	* it.
	129	*
	130	* Atomic: we hold the counter->ctx->lock and we only handle variables
	131	* and registers local to this cpu.
0067f129	132	*/
24f1e32c	133	void arch_uninstall_hw_breakpoint(struct perf_event *bp)
0067f129	134	{
24f1e32c FW	135	struct arch_hw_breakpoint *info = counter_arch_bp(bp);
	136	unsigned long *dr7;
	137	int i;
	138
	139	for (i = 0; i < HBP_NUM; i++) {
	140	struct perf_event **slot = &__get_cpu_var(bp_per_reg[i]);
	141
	142	if (*slot == bp) {
	143	*slot = NULL;
	144	break;
	145	}
	146	}
	147
	148	if (WARN_ONCE(i == HBP_NUM, "Can't find any breakpoint slot"))
	149	return;
0067f129	150
24f1e32c FW	151	dr7 = &__get_cpu_var(dr7);
	152	*dr7 &= ~encode_dr7(i, info->len, info->type);
	153
	154	set_debugreg(*dr7, 7);
0067f129 P	155	}
	156
	157	static int get_hbp_len(u8 hbp_len)
	158	{
	159	unsigned int len_in_bytes = 0;
	160
	161	switch (hbp_len) {
24f1e32c	162	case X86_BREAKPOINT_LEN_1:
0067f129 P	163	len_in_bytes = 1;
0067f129 P	164	break;
24f1e32c	165	case X86_BREAKPOINT_LEN_2:
0067f129 P	166	len_in_bytes = 2;
0067f129 P	167	break;
24f1e32c	168	case X86_BREAKPOINT_LEN_4:
0067f129 P	169	len_in_bytes = 4;
	170	break;
	171	#ifdef CONFIG_X86_64
24f1e32c	172	case X86_BREAKPOINT_LEN_8:
0067f129 P	173	len_in_bytes = 8;
	174	break;
	175	#endif
	176	}
	177	return len_in_bytes;
	178	}
	179
	180	/*
	181	* Check for virtual address in user space.
	182	*/
	183	int arch_check_va_in_userspace(unsigned long va, u8 hbp_len)
	184	{
	185	unsigned int len;
	186
	187	len = get_hbp_len(hbp_len);
	188
	189	return (va <= TASK_SIZE - len);
	190	}
	191
	192	/*
	193	* Check for virtual address in kernel space.
	194	*/
4555835b	195	static int arch_check_va_in_kernelspace(unsigned long va, u8 hbp_len)
0067f129 P	196	{
	197	unsigned int len;
	198
	199	len = get_hbp_len(hbp_len);
	200
	201	return (va >= TASK_SIZE) && ((va + len - 1) >= TASK_SIZE);
	202	}
	203
	204	/*
	205	* Store a breakpoint's encoded address, length, and type.
	206	*/
24f1e32c	207	static int arch_store_info(struct perf_event *bp)
0067f129	208	{
24f1e32c	209	struct arch_hw_breakpoint *info = counter_arch_bp(bp);
0067f129 P	210	/*
	211	* For kernel-addresses, either the address or symbol name can be
	212	* specified.
	213	*/
24f1e32c FW	214	if (info->name)
	215	info->address = (unsigned long)
	216	kallsyms_lookup_name(info->name);
	217	if (info->address)
0067f129	218	return 0;
24f1e32c	219
0067f129 P	220	return -EINVAL;
	221	}
	222
24f1e32c FW	223	int arch_bp_generic_fields(int x86_len, int x86_type,
24f1e32c FW	224	int gen_len, int gen_type)
0067f129	225	{
24f1e32c FW	226	/* Len */
	227	switch (x86_len) {
	228	case X86_BREAKPOINT_LEN_1:
	229	*gen_len = HW_BREAKPOINT_LEN_1;
	230	break;
	231	case X86_BREAKPOINT_LEN_2:
	232	*gen_len = HW_BREAKPOINT_LEN_2;
	233	break;
	234	case X86_BREAKPOINT_LEN_4:
	235	*gen_len = HW_BREAKPOINT_LEN_4;
	236	break;
	237	#ifdef CONFIG_X86_64
	238	case X86_BREAKPOINT_LEN_8:
	239	*gen_len = HW_BREAKPOINT_LEN_8;
	240	break;
	241	#endif
	242	default:
	243	return -EINVAL;
	244	}
0067f129	245
24f1e32c FW	246	/* Type */
	247	switch (x86_type) {
	248	case X86_BREAKPOINT_EXECUTE:
	249	*gen_type = HW_BREAKPOINT_X;
0067f129	250	break;
24f1e32c FW	251	case X86_BREAKPOINT_WRITE:
24f1e32c FW	252	*gen_type = HW_BREAKPOINT_W;
0067f129	253	break;
24f1e32c FW	254	case X86_BREAKPOINT_RW:
24f1e32c FW	255	*gen_type = HW_BREAKPOINT_W \| HW_BREAKPOINT_R;
0067f129 P	256	break;
0067f129 P	257	default:
24f1e32c	258	return -EINVAL;
0067f129 P	259	}
0067f129 P	260
24f1e32c FW	261	return 0;
	262	}
	263
	264
	265	static int arch_build_bp_info(struct perf_event *bp)
	266	{
	267	struct arch_hw_breakpoint *info = counter_arch_bp(bp);
	268
	269	info->address = bp->attr.bp_addr;
	270
	271	/* Len */
	272	switch (bp->attr.bp_len) {
0067f129	273	case HW_BREAKPOINT_LEN_1:
24f1e32c	274	info->len = X86_BREAKPOINT_LEN_1;
0067f129 P	275	break;
0067f129 P	276	case HW_BREAKPOINT_LEN_2:
24f1e32c	277	info->len = X86_BREAKPOINT_LEN_2;
0067f129 P	278	break;
0067f129 P	279	case HW_BREAKPOINT_LEN_4:
24f1e32c	280	info->len = X86_BREAKPOINT_LEN_4;
0067f129 P	281	break;
	282	#ifdef CONFIG_X86_64
	283	case HW_BREAKPOINT_LEN_8:
24f1e32c FW	284	info->len = X86_BREAKPOINT_LEN_8;
	285	break;
	286	#endif
	287	default:
	288	return -EINVAL;
	289	}
	290
	291	/* Type */
	292	switch (bp->attr.bp_type) {
	293	case HW_BREAKPOINT_W:
	294	info->type = X86_BREAKPOINT_WRITE;
	295	break;
	296	case HW_BREAKPOINT_W \| HW_BREAKPOINT_R:
	297	info->type = X86_BREAKPOINT_RW;
	298	break;
	299	case HW_BREAKPOINT_X:
	300	info->type = X86_BREAKPOINT_EXECUTE;
	301	break;
	302	default:
	303	return -EINVAL;
	304	}
	305
	306	return 0;
	307	}
	308	/*
	309	* Validate the arch-specific HW Breakpoint register settings
	310	*/
	311	int arch_validate_hwbkpt_settings(struct perf_event *bp,
	312	struct task_struct *tsk)
	313	{
	314	struct arch_hw_breakpoint *info = counter_arch_bp(bp);
	315	unsigned int align;
	316	int ret;
	317
	318
	319	ret = arch_build_bp_info(bp);
	320	if (ret)
	321	return ret;
	322
	323	ret = -EINVAL;
	324
	325	if (info->type == X86_BREAKPOINT_EXECUTE)
	326	/*
	327	* Ptrace-refactoring code
	328	* For now, we'll allow instruction breakpoint only for user-space
	329	* addresses
	330	*/
	331	if ((!arch_check_va_in_userspace(info->address, info->len)) &&
	332	info->len != X86_BREAKPOINT_EXECUTE)
	333	return ret;
	334
	335	switch (info->len) {
	336	case X86_BREAKPOINT_LEN_1:
	337	align = 0;
	338	break;
	339	case X86_BREAKPOINT_LEN_2:
	340	align = 1;
	341	break;
	342	case X86_BREAKPOINT_LEN_4:
	343	align = 3;
	344	break;
	345	#ifdef CONFIG_X86_64
	346	case X86_BREAKPOINT_LEN_8:
0067f129 P	347	align = 7;
	348	break;
	349	#endif
	350	default:
	351	return ret;
	352	}
	353
24f1e32c FW	354	if (bp->callback)
24f1e32c FW	355	ret = arch_store_info(bp);
0067f129 P	356
	357	if (ret < 0)
	358	return ret;
	359	/*
	360	* Check that the low-order bits of the address are appropriate
	361	* for the alignment implied by len.
	362	*/
24f1e32c	363	if (info->address & align)
0067f129 P	364	return -EINVAL;
	365
	366	/* Check that the virtual address is in the proper range */
	367	if (tsk) {
24f1e32c	368	if (!arch_check_va_in_userspace(info->address, info->len))
0067f129 P	369	return -EFAULT;
0067f129 P	370	} else {
24f1e32c	371	if (!arch_check_va_in_kernelspace(info->address, info->len))
0067f129 P	372	return -EFAULT;
0067f129 P	373	}
24f1e32c	374
0067f129 P	375	return 0;
	376	}
	377
9f6b3c2c FW	378	/*
	379	* Dump the debug register contents to the user.
	380	* We can't dump our per cpu values because it
	381	* may contain cpu wide breakpoint, something that
	382	* doesn't belong to the current task.
	383	*
	384	* TODO: include non-ptrace user breakpoints (perf)
	385	*/
	386	void aout_dump_debugregs(struct user *dump)
	387	{
	388	int i;
	389	int dr7 = 0;
	390	struct perf_event *bp;
	391	struct arch_hw_breakpoint *info;
	392	struct thread_struct *thread = &current->thread;
	393
	394	for (i = 0; i < HBP_NUM; i++) {
	395	bp = thread->ptrace_bps[i];
	396
	397	if (bp && !bp->attr.disabled) {
	398	dump->u_debugreg[i] = bp->attr.bp_addr;
	399	info = counter_arch_bp(bp);
	400	dr7 \|= encode_dr7(i, info->len, info->type);
	401	} else {
	402	dump->u_debugreg[i] = 0;
	403	}
	404	}
	405
	406	dump->u_debugreg[4] = 0;
	407	dump->u_debugreg[5] = 0;
	408	dump->u_debugreg[6] = current->thread.debugreg6;
	409
	410	dump->u_debugreg[7] = dr7;
	411	}
	412
24f1e32c FW	413	/*
	414	* Release the user breakpoints used by ptrace
	415	*/
	416	void flush_ptrace_hw_breakpoint(struct task_struct *tsk)
0067f129	417	{
24f1e32c FW	418	int i;
	419	struct thread_struct *t = &tsk->thread;
	420
	421	for (i = 0; i < HBP_NUM; i++) {
	422	unregister_hw_breakpoint(t->ptrace_bps[i]);
	423	t->ptrace_bps[i] = NULL;
	424	}
0067f129 P	425	}
0067f129 P	426
24f1e32c FW	427	#ifdef CONFIG_KVM
24f1e32c FW	428	void hw_breakpoint_restore(void)
0067f129	429	{
24f1e32c FW	430	set_debugreg(__get_cpu_var(cpu_debugreg[0]), 0);
	431	set_debugreg(__get_cpu_var(cpu_debugreg[1]), 1);
	432	set_debugreg(__get_cpu_var(cpu_debugreg[2]), 2);
	433	set_debugreg(__get_cpu_var(cpu_debugreg[3]), 3);
	434	set_debugreg(current->thread.debugreg6, 6);
	435	set_debugreg(__get_cpu_var(dr7), 7);
0067f129	436	}
24f1e32c FW	437	EXPORT_SYMBOL_GPL(hw_breakpoint_restore);
24f1e32c FW	438	#endif
0067f129 P	439
	440	/*
	441	* Handle debug exception notifications.
	442	*
	443	* Return value is either NOTIFY_STOP or NOTIFY_DONE as explained below.
	444	*
	445	* NOTIFY_DONE returned if one of the following conditions is true.
	446	* i) When the causative address is from user-space and the exception
	447	* is a valid one, i.e. not triggered as a result of lazy debug register
	448	* switching
	449	* ii) When there are more bits than trap<n> set in DR6 register (such
	450	* as BD, BS or BT) indicating that more than one debug condition is
	451	* met and requires some more action in do_debug().
	452	*
	453	* NOTIFY_STOP returned for all other cases
	454	*
	455	*/
4555835b	456	static int __kprobes hw_breakpoint_handler(struct die_args *args)
0067f129 P	457	{
0067f129 P	458	int i, cpu, rc = NOTIFY_STOP;
24f1e32c	459	struct perf_event *bp;
62edab90 P	460	unsigned long dr7, dr6;
	461	unsigned long *dr6_p;
	462
	463	/* The DR6 value is pointed by args->err */
	464	dr6_p = (unsigned long *)ERR_PTR(args->err);
	465	dr6 = *dr6_p;
0067f129 P	466
	467	/* Do an early return if no trap bits are set in DR6 */
	468	if ((dr6 & DR_TRAP_BITS) == 0)
	469	return NOTIFY_DONE;
	470
0067f129 P	471	get_debugreg(dr7, 7);
	472	/* Disable breakpoints during exception handling */
	473	set_debugreg(0UL, 7);
	474	/*
	475	* Assert that local interrupts are disabled
	476	* Reset the DRn bits in the virtualized register value.
	477	* The ptrace trigger routine will add in whatever is needed.
	478	*/
	479	current->thread.debugreg6 &= ~DR_TRAP_BITS;
	480	cpu = get_cpu();
	481
	482	/* Handle all the breakpoints that were triggered */
	483	for (i = 0; i < HBP_NUM; ++i) {
	484	if (likely(!(dr6 & (DR_TRAP0 << i))))
	485	continue;
24f1e32c	486
0067f129	487	/*
24f1e32c FW	488	* The counter may be concurrently released but that can only
	489	* occur from a call_rcu() path. We can then safely fetch
	490	* the breakpoint, use its callback, touch its counter
	491	* while we are in an rcu_read_lock() path.
0067f129	492	*/
24f1e32c FW	493	rcu_read_lock();
	494
	495	bp = per_cpu(bp_per_reg[i], cpu);
	496	if (bp)
	497	rc = NOTIFY_DONE;
62edab90 P	498	/*
	499	* Reset the 'i'th TRAP bit in dr6 to denote completion of
	500	* exception handling
	501	*/
	502	(*dr6_p) &= ~(DR_TRAP0 << i);
0067f129 P	503	/*
0067f129 P	504	* bp can be NULL due to lazy debug register switching
24f1e32c	505	* or due to concurrent perf counter removing.
0067f129	506	*/
24f1e32c FW	507	if (!bp) {
	508	rcu_read_unlock();
	509	break;
	510	}
	511
	512	(bp->callback)(bp, args->regs);
0067f129	513
24f1e32c	514	rcu_read_unlock();
0067f129 P	515	}
	516	if (dr6 & (~DR_TRAP_BITS))
	517	rc = NOTIFY_DONE;
	518
	519	set_debugreg(dr7, 7);
eadb8a09	520	put_cpu();
24f1e32c	521
0067f129 P	522	return rc;
	523	}
	524
	525	/*
	526	* Handle debug exception notifications.
	527	*/
	528	int __kprobes hw_breakpoint_exceptions_notify(
	529	struct notifier_block unused, unsigned long val, void data)
	530	{
	531	if (val != DIE_DEBUG)
	532	return NOTIFY_DONE;
	533
	534	return hw_breakpoint_handler(data);
	535	}
24f1e32c FW	536
	537	void hw_breakpoint_pmu_read(struct perf_event *bp)
	538	{
	539	/* TODO */
	540	}
	541
	542	void hw_breakpoint_pmu_unthrottle(struct perf_event *bp)
	543	{
	544	/* TODO */
	545	}