[linux-2.6-block.git] / kernel / trace / trace_ksym.c

/*
 * trace_ksym.c - Kernel Symbol Tracer
 *
 * 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) IBM Corporation, 2009
 */

#include <linux/kallsyms.h>
#include <linux/uaccess.h>
#include <linux/debugfs.h>
#include <linux/ftrace.h>
#include <linux/module.h>
#include <linux/fs.h>

#include "trace_output.h"
#include "trace_stat.h"
#include "trace.h"

/* For now, let us restrict the no. of symbols traced simultaneously to number
 * of available hardware breakpoint registers.
 */
#define KSYM_TRACER_MAX HBP_NUM

#define KSYM_TRACER_OP_LEN 3 /* rw- */

struct trace_ksym {
	struct hw_breakpoint	*ksym_hbp;
	unsigned long		ksym_addr;
#ifdef CONFIG_PROFILE_KSYM_TRACER
	unsigned long		counter;
#endif
	struct hlist_node	ksym_hlist;
};

static struct trace_array *ksym_trace_array;

static unsigned int ksym_filter_entry_count;
static unsigned int ksym_tracing_enabled;

static HLIST_HEAD(ksym_filter_head);

static DEFINE_MUTEX(ksym_tracer_mutex);

#ifdef CONFIG_PROFILE_KSYM_TRACER

#define MAX_UL_INT 0xffffffff

void ksym_collect_stats(unsigned long hbp_hit_addr)
{
	struct hlist_node *node;
	struct trace_ksym *entry;

	rcu_read_lock();
	hlist_for_each_entry_rcu(entry, node, &ksym_filter_head, ksym_hlist) {
		if ((entry->ksym_addr == hbp_hit_addr) &&
		    (entry->counter <= MAX_UL_INT)) {
			entry->counter++;
			break;
		}
	}
	rcu_read_unlock();
}
#endif /* CONFIG_PROFILE_KSYM_TRACER */

void ksym_hbp_handler(struct hw_breakpoint *hbp, struct pt_regs *regs)
{
	struct ring_buffer_event *event;
	struct trace_array *tr;
	struct ksym_trace_entry *entry;
	int pc;

	if (!ksym_tracing_enabled)
		return;

	tr = ksym_trace_array;
	pc = preempt_count();

	event = trace_buffer_lock_reserve(tr, TRACE_KSYM,
							sizeof(*entry), 0, pc);
	if (!event)
		return;

	entry		= ring_buffer_event_data(event);
	entry->ip	= instruction_pointer(regs);
	entry->type	= hbp->info.type;
	strlcpy(entry->ksym_name, hbp->info.name, KSYM_SYMBOL_LEN);
	strlcpy(entry->cmd, current->comm, TASK_COMM_LEN);

#ifdef CONFIG_PROFILE_KSYM_TRACER
	ksym_collect_stats(hbp->info.address);
#endif /* CONFIG_PROFILE_KSYM_TRACER */

	trace_buffer_unlock_commit(tr, event, 0, pc);
}

/* Valid access types are represented as
 *
 * rw- : Set Read/Write Access Breakpoint
 * -w- : Set Write Access Breakpoint
 * --- : Clear Breakpoints
 * --x : Set Execution Break points (Not available yet)
 *
 */
static int ksym_trace_get_access_type(char *str)
{
	int access = 0;

	if (str[0] == 'r')
		access += 4;
	else if (str[0] != '-')
		return -EINVAL;

	if (str[1] == 'w')
		access += 2;
	else if (str[1] != '-')
		return -EINVAL;

	if (str[2] != '-')
		return -EINVAL;

	switch (access) {
	case 6:
		access = HW_BREAKPOINT_RW;
		break;
	case 4:
		access = -EINVAL;
		break;
	case 2:
		access = HW_BREAKPOINT_WRITE;
		break;
	}

	return access;
}

/*
 * There can be several possible malformed requests and we attempt to capture
 * all of them. We enumerate some of the rules
 * 1. We will not allow kernel symbols with ':' since it is used as a delimiter.
 *    i.e. multiple ':' symbols disallowed. Possible uses are of the form
 *    <module>:<ksym_name>:<op>.
 * 2. No delimiter symbol ':' in the input string
 * 3. Spurious operator symbols or symbols not in their respective positions
 * 4. <ksym_name>:--- i.e. clear breakpoint request when ksym_name not in file
 * 5. Kernel symbol not a part of /proc/kallsyms
 * 6. Duplicate requests
 */
static int parse_ksym_trace_str(char *input_string, char **ksymname,
							unsigned long *addr)
{
	int ret;

	*ksymname = strsep(&input_string, ":");
	*addr = kallsyms_lookup_name(*ksymname);

	/* Check for malformed request: (2), (1) and (5) */
	if ((!input_string) ||
	    (strlen(input_string) != KSYM_TRACER_OP_LEN) ||
	    (*addr == 0))
		return -EINVAL;;

	ret = ksym_trace_get_access_type(input_string);

	return ret;
}

int process_new_ksym_entry(char *ksymname, int op, unsigned long addr)
{
	struct trace_ksym *entry;
	int ret = -ENOMEM;

	if (ksym_filter_entry_count >= KSYM_TRACER_MAX) {
		printk(KERN_ERR "ksym_tracer: Maximum limit:(%d) reached. No"
		" new requests for tracing can be accepted now.\n",
			KSYM_TRACER_MAX);
		return -ENOSPC;
	}

	entry = kzalloc(sizeof(struct trace_ksym), GFP_KERNEL);
	if (!entry)
		return -ENOMEM;

	entry->ksym_hbp = kzalloc(sizeof(struct hw_breakpoint), GFP_KERNEL);
	if (!entry->ksym_hbp)
		goto err;

	entry->ksym_hbp->info.name = kstrdup(ksymname, GFP_KERNEL);
	if (!entry->ksym_hbp->info.name)
		goto err;

	entry->ksym_hbp->info.type = op;
	entry->ksym_addr = entry->ksym_hbp->info.address = addr;
#ifdef CONFIG_X86
	entry->ksym_hbp->info.len = HW_BREAKPOINT_LEN_4;
#endif
	entry->ksym_hbp->triggered = (void *)ksym_hbp_handler;

	ret = register_kernel_hw_breakpoint(entry->ksym_hbp);
	if (ret < 0) {
		printk(KERN_INFO "ksym_tracer request failed. Try again"
					" later!!\n");
		ret = -EAGAIN;
		goto err;
	}
	hlist_add_head_rcu(&(entry->ksym_hlist), &ksym_filter_head);
	ksym_filter_entry_count++;
	return 0;
err:
	if (entry->ksym_hbp)
		kfree(entry->ksym_hbp->info.name);
	kfree(entry->ksym_hbp);
	kfree(entry);
	return ret;
}

static ssize_t ksym_trace_filter_read(struct file *filp, char __user *ubuf,
						size_t count, loff_t *ppos)
{
	struct trace_ksym *entry;
	struct hlist_node *node;
	struct trace_seq *s;
	ssize_t cnt = 0;
	int ret;

	s = kmalloc(sizeof(*s), GFP_KERNEL);
	if (!s)
		return -ENOMEM;
	trace_seq_init(s);

	mutex_lock(&ksym_tracer_mutex);

	hlist_for_each_entry(entry, node, &ksym_filter_head, ksym_hlist) {
		ret = trace_seq_printf(s, "%s:", entry->ksym_hbp->info.name);
		if (entry->ksym_hbp->info.type == HW_BREAKPOINT_WRITE)
			ret = trace_seq_puts(s, "-w-\n");
		else if (entry->ksym_hbp->info.type == HW_BREAKPOINT_RW)
			ret = trace_seq_puts(s, "rw-\n");
		WARN_ON_ONCE(!ret);
	}

	cnt = simple_read_from_buffer(ubuf, count, ppos, s->buffer, s->len);

	mutex_unlock(&ksym_tracer_mutex);

	kfree(s);

	return cnt;
}

static void __ksym_trace_reset(void)
{
	struct trace_ksym *entry;
	struct hlist_node *node, *node1;

	mutex_lock(&ksym_tracer_mutex);
	hlist_for_each_entry_safe(entry, node, node1, &ksym_filter_head,
								ksym_hlist) {
		unregister_kernel_hw_breakpoint(entry->ksym_hbp);
		ksym_filter_entry_count--;
		hlist_del_rcu(&(entry->ksym_hlist));
		synchronize_rcu();
		kfree(entry->ksym_hbp->info.name);
		kfree(entry->ksym_hbp);
		kfree(entry);
	}
	mutex_unlock(&ksym_tracer_mutex);
}

static ssize_t ksym_trace_filter_write(struct file *file,
					const char __user *buffer,
						size_t count, loff_t *ppos)
{
	struct trace_ksym *entry;
	struct hlist_node *node;
	char *input_string, *ksymname = NULL;
	unsigned long ksym_addr = 0;
	int ret, op, changed = 0;

	input_string = kzalloc(count + 1, GFP_KERNEL);
	if (!input_string)
		return -ENOMEM;

	if (copy_from_user(input_string, buffer, count)) {
		kfree(input_string);
		return -EFAULT;
	}
	input_string[count] = '\0';

	strstrip(input_string);

	/*
	 * Clear all breakpoints if:
	 * 1: echo > ksym_trace_filter
	 * 2: echo 0 > ksym_trace_filter
	 * 3: echo "*:---" > ksym_trace_filter
	 */
	if (!input_string[0] || !strcmp(input_string, "0") ||
	    !strcmp(input_string, "*:---")) {
		__ksym_trace_reset();
		kfree(input_string);
		return count;
	}

	ret = op = parse_ksym_trace_str(input_string, &ksymname, &ksym_addr);
	if (ret < 0) {
		kfree(input_string);
		return ret;
	}

	mutex_lock(&ksym_tracer_mutex);

	ret = -EINVAL;
	hlist_for_each_entry(entry, node, &ksym_filter_head, ksym_hlist) {
		if (entry->ksym_addr == ksym_addr) {
			/* Check for malformed request: (6) */
			if (entry->ksym_hbp->info.type != op)
				changed = 1;
			else
				goto out;
			break;
		}
	}
	if (changed) {
		unregister_kernel_hw_breakpoint(entry->ksym_hbp);
		entry->ksym_hbp->info.type = op;
		if (op > 0) {
			ret = register_kernel_hw_breakpoint(entry->ksym_hbp);
			if (ret == 0)
				goto out;
		}
		ksym_filter_entry_count--;
		hlist_del_rcu(&(entry->ksym_hlist));
		synchronize_rcu();
		kfree(entry->ksym_hbp->info.name);
		kfree(entry->ksym_hbp);
		kfree(entry);
		ret = 0;
		goto out;
	} else {
		/* Check for malformed request: (4) */
		if (op == 0)
			goto out;
		ret = process_new_ksym_entry(ksymname, op, ksym_addr);
	}
out:
	mutex_unlock(&ksym_tracer_mutex);

	kfree(input_string);

	if (!ret)
		ret = count;
	return ret;
}

static const struct file_operations ksym_tracing_fops = {
	.open		= tracing_open_generic,
	.read		= ksym_trace_filter_read,
	.write		= ksym_trace_filter_write,
};

static void ksym_trace_reset(struct trace_array *tr)
{
	ksym_tracing_enabled = 0;
	__ksym_trace_reset();
}

static int ksym_trace_init(struct trace_array *tr)
{
	int cpu, ret = 0;

	for_each_online_cpu(cpu)
		tracing_reset(tr, cpu);
	ksym_tracing_enabled = 1;
	ksym_trace_array = tr;

	return ret;
}

static void ksym_trace_print_header(struct seq_file *m)
{
	seq_puts(m,
		 "#       TASK-PID   CPU#      Symbol                    "
		 "Type    Function\n");
	seq_puts(m,
		 "#          |        |          |                       "
		 " |         |\n");
}

static enum print_line_t ksym_trace_output(struct trace_iterator *iter)
{
	struct trace_entry *entry = iter->ent;
	struct trace_seq *s = &iter->seq;
	struct ksym_trace_entry *field;
	char str[KSYM_SYMBOL_LEN];
	int ret;

	if (entry->type != TRACE_KSYM)
		return TRACE_TYPE_UNHANDLED;

	trace_assign_type(field, entry);

	ret = trace_seq_printf(s, "%11s-%-5d [%03d] %-30s ", field->cmd,
				entry->pid, iter->cpu, field->ksym_name);
	if (!ret)
		return TRACE_TYPE_PARTIAL_LINE;

	switch (field->type) {
	case HW_BREAKPOINT_WRITE:
		ret = trace_seq_printf(s, " W  ");
		break;
	case HW_BREAKPOINT_RW:
		ret = trace_seq_printf(s, " RW ");
		break;
	default:
		return TRACE_TYPE_PARTIAL_LINE;
	}

	if (!ret)
		return TRACE_TYPE_PARTIAL_LINE;

	sprint_symbol(str, field->ip);
	ret = trace_seq_printf(s, "%s\n", str);
	if (!ret)
		return TRACE_TYPE_PARTIAL_LINE;

	return TRACE_TYPE_HANDLED;
}

struct tracer ksym_tracer __read_mostly =
{
	.name		= "ksym_tracer",
	.init		= ksym_trace_init,
	.reset		= ksym_trace_reset,
#ifdef CONFIG_FTRACE_SELFTEST
	.selftest	= trace_selftest_startup_ksym,
#endif
	.print_header   = ksym_trace_print_header,
	.print_line	= ksym_trace_output
};

__init static int init_ksym_trace(void)
{
	struct dentry *d_tracer;
	struct dentry *entry;

	d_tracer = tracing_init_dentry();
	ksym_filter_entry_count = 0;

	entry = debugfs_create_file("ksym_trace_filter", 0644, d_tracer,
				    NULL, &ksym_tracing_fops);
	if (!entry)
		pr_warning("Could not create debugfs "
			   "'ksym_trace_filter' file\n");

	return register_tracer(&ksym_tracer);
}
device_initcall(init_ksym_trace);


#ifdef CONFIG_PROFILE_KSYM_TRACER
static int ksym_tracer_stat_headers(struct seq_file *m)
{
	seq_puts(m, "  Access Type ");
	seq_puts(m, "  Symbol                                       Counter\n");
	seq_puts(m, "  ----------- ");
	seq_puts(m, "  ------                                       -------\n");
	return 0;
}

static int ksym_tracer_stat_show(struct seq_file *m, void *v)
{
	struct hlist_node *stat = v;
	struct trace_ksym *entry;
	int access_type = 0;
	char fn_name[KSYM_NAME_LEN];

	entry = hlist_entry(stat, struct trace_ksym, ksym_hlist);

	if (entry->ksym_hbp)
		access_type = entry->ksym_hbp->info.type;

	switch (access_type) {
	case HW_BREAKPOINT_WRITE:
		seq_puts(m, "  W           ");
		break;
	case HW_BREAKPOINT_RW:
		seq_puts(m, "  RW          ");
		break;
	default:
		seq_puts(m, "  NA          ");
	}

	if (lookup_symbol_name(entry->ksym_addr, fn_name) >= 0)
		seq_printf(m, "  %-36s", fn_name);
	else
		seq_printf(m, "  %-36s", "<NA>");
	seq_printf(m, " %15lu\n", entry->counter);

	return 0;
}

static void *ksym_tracer_stat_start(struct tracer_stat *trace)
{
	return ksym_filter_head.first;
}

static void *
ksym_tracer_stat_next(void *v, int idx)
{
	struct hlist_node *stat = v;

	return stat->next;
}

static struct tracer_stat ksym_tracer_stats = {
	.name = "ksym_tracer",
	.stat_start = ksym_tracer_stat_start,
	.stat_next = ksym_tracer_stat_next,
	.stat_headers = ksym_tracer_stat_headers,
	.stat_show = ksym_tracer_stat_show
};

__init static int ksym_tracer_stat_init(void)
{
	int ret;

	ret = register_stat_tracer(&ksym_tracer_stats);
	if (ret) {
		printk(KERN_WARNING "Warning: could not register "
				    "ksym tracer stats\n");
		return 1;
	}

	return 0;
}
fs_initcall(ksym_tracer_stat_init);
#endif /* CONFIG_PROFILE_KSYM_TRACER */
Commit	Line	Data
0722db01 P	1	/*
	2	* trace_ksym.c - Kernel Symbol Tracer
	3	*
	4	* This program is free software; you can redistribute it and/or modify
	5	* it under the terms of the GNU General Public License as published by
	6	* the Free Software Foundation; either version 2 of the License, or
	7	* (at your option) any later version.
	8	*
	9	* This program is distributed in the hope that it will be useful,
	10	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	11	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	12	* GNU General Public License for more details.
	13	*
	14	* You should have received a copy of the GNU General Public License
	15	* along with this program; if not, write to the Free Software
	16	* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
	17	*
	18	* Copyright (C) IBM Corporation, 2009
	19	*/
	20
	21	#include <linux/kallsyms.h>
	22	#include <linux/uaccess.h>
	23	#include <linux/debugfs.h>
	24	#include <linux/ftrace.h>
	25	#include <linux/module.h>
	26	#include <linux/fs.h>
	27
	28	#include "trace_output.h"
	29	#include "trace_stat.h"
	30	#include "trace.h"
	31
	32	/* For now, let us restrict the no. of symbols traced simultaneously to number
	33	* of available hardware breakpoint registers.
	34	*/
	35	#define KSYM_TRACER_MAX HBP_NUM
	36
	37	#define KSYM_TRACER_OP_LEN 3 /* rw- */
0722db01	38
db59504d LZ	39	struct trace_ksym {
	40	struct hw_breakpoint *ksym_hbp;
	41	unsigned long ksym_addr;
	42	#ifdef CONFIG_PROFILE_KSYM_TRACER
	43	unsigned long counter;
	44	#endif
	45	struct hlist_node ksym_hlist;
	46	};
	47
0722db01 P	48	static struct trace_array *ksym_trace_array;
	49
	50	static unsigned int ksym_filter_entry_count;
	51	static unsigned int ksym_tracing_enabled;
	52
	53	static HLIST_HEAD(ksym_filter_head);
	54
73874005 FW	55	static DEFINE_MUTEX(ksym_tracer_mutex);
73874005 FW	56
0722db01 P	57	#ifdef CONFIG_PROFILE_KSYM_TRACER
	58
	59	#define MAX_UL_INT 0xffffffff
	60
0722db01 P	61	void ksym_collect_stats(unsigned long hbp_hit_addr)
	62	{
	63	struct hlist_node *node;
	64	struct trace_ksym *entry;
	65
	66	rcu_read_lock();
	67	hlist_for_each_entry_rcu(entry, node, &ksym_filter_head, ksym_hlist) {
	68	if ((entry->ksym_addr == hbp_hit_addr) &&
	69	(entry->counter <= MAX_UL_INT)) {
	70	entry->counter++;
	71	break;
	72	}
	73	}
	74	rcu_read_unlock();
	75	}
	76	#endif /* CONFIG_PROFILE_KSYM_TRACER */
	77
	78	void ksym_hbp_handler(struct hw_breakpoint hbp, struct pt_regs regs)
	79	{
	80	struct ring_buffer_event *event;
	81	struct trace_array *tr;
db59504d	82	struct ksym_trace_entry *entry;
0722db01 P	83	int pc;
	84
	85	if (!ksym_tracing_enabled)
	86	return;
	87
	88	tr = ksym_trace_array;
	89	pc = preempt_count();
	90
	91	event = trace_buffer_lock_reserve(tr, TRACE_KSYM,
	92	sizeof(*entry), 0, pc);
	93	if (!event)
	94	return;
	95
db59504d LZ	96	entry = ring_buffer_event_data(event);
	97	entry->ip = instruction_pointer(regs);
	98	entry->type = hbp->info.type;
0722db01	99	strlcpy(entry->ksym_name, hbp->info.name, KSYM_SYMBOL_LEN);
db59504d LZ	100	strlcpy(entry->cmd, current->comm, TASK_COMM_LEN);
db59504d LZ	101
0722db01 P	102	#ifdef CONFIG_PROFILE_KSYM_TRACER
	103	ksym_collect_stats(hbp->info.address);
	104	#endif /* CONFIG_PROFILE_KSYM_TRACER */
	105
	106	trace_buffer_unlock_commit(tr, event, 0, pc);
	107	}
	108
	109	/* Valid access types are represented as
	110	*
	111	* rw- : Set Read/Write Access Breakpoint
	112	* -w- : Set Write Access Breakpoint
	113	* --- : Clear Breakpoints
	114	* --x : Set Execution Break points (Not available yet)
	115	*
	116	*/
f088e547	117	static int ksym_trace_get_access_type(char *str)
0722db01	118	{
f088e547	119	int access = 0;
0722db01	120
f088e547 LZ	121	if (str[0] == 'r')
	122	access += 4;
	123	else if (str[0] != '-')
	124	return -EINVAL;
	125
	126	if (str[1] == 'w')
	127	access += 2;
	128	else if (str[1] != '-')
	129	return -EINVAL;
	130
	131	if (str[2] != '-')
	132	return -EINVAL;
0722db01 P	133
	134	switch (access) {
	135	case 6:
	136	access = HW_BREAKPOINT_RW;
	137	break;
8e068542 XG	138	case 4:
	139	access = -EINVAL;
	140	break;
0722db01 P	141	case 2:
	142	access = HW_BREAKPOINT_WRITE;
	143	break;
0722db01 P	144	}
	145
	146	return access;
	147	}
	148
	149	/*
	150	* There can be several possible malformed requests and we attempt to capture
	151	* all of them. We enumerate some of the rules
	152	* 1. We will not allow kernel symbols with ':' since it is used as a delimiter.
	153	* i.e. multiple ':' symbols disallowed. Possible uses are of the form
	154	* <module>:<ksym_name>:<op>.
	155	* 2. No delimiter symbol ':' in the input string
	156	* 3. Spurious operator symbols or symbols not in their respective positions
	157	* 4. <ksym_name>:--- i.e. clear breakpoint request when ksym_name not in file
	158	* 5. Kernel symbol not a part of /proc/kallsyms
	159	* 6. Duplicate requests
	160	*/
	161	static int parse_ksym_trace_str(char input_string, char *ksymname,
	162	unsigned long *addr)
	163	{
0722db01 P	164	int ret;
0722db01 P	165
92cf9f8f	166	*ksymname = strsep(&input_string, ":");
0722db01 P	167	addr = kallsyms_lookup_name(ksymname);
	168
	169	/* Check for malformed request: (2), (1) and (5) */
	170	if ((!input_string) \|\|
92cf9f8f LZ	171	(strlen(input_string) != KSYM_TRACER_OP_LEN) \|\|
	172	(*addr == 0))
	173	return -EINVAL;;
	174
0722db01 P	175	ret = ksym_trace_get_access_type(input_string);
0722db01 P	176
0722db01 P	177	return ret;
	178	}
	179
	180	int process_new_ksym_entry(char *ksymname, int op, unsigned long addr)
	181	{
	182	struct trace_ksym *entry;
558df6c8	183	int ret = -ENOMEM;
0722db01 P	184
	185	if (ksym_filter_entry_count >= KSYM_TRACER_MAX) {
	186	printk(KERN_ERR "ksym_tracer: Maximum limit:(%d) reached. No"
	187	" new requests for tracing can be accepted now.\n",
	188	KSYM_TRACER_MAX);
	189	return -ENOSPC;
	190	}
	191
	192	entry = kzalloc(sizeof(struct trace_ksym), GFP_KERNEL);
	193	if (!entry)
	194	return -ENOMEM;
	195
	196	entry->ksym_hbp = kzalloc(sizeof(struct hw_breakpoint), GFP_KERNEL);
558df6c8 LZ	197	if (!entry->ksym_hbp)
	198	goto err;
	199
	200	entry->ksym_hbp->info.name = kstrdup(ksymname, GFP_KERNEL);
	201	if (!entry->ksym_hbp->info.name)
	202	goto err;
0722db01	203
0722db01 P	204	entry->ksym_hbp->info.type = op;
	205	entry->ksym_addr = entry->ksym_hbp->info.address = addr;
	206	#ifdef CONFIG_X86
	207	entry->ksym_hbp->info.len = HW_BREAKPOINT_LEN_4;
	208	#endif
	209	entry->ksym_hbp->triggered = (void *)ksym_hbp_handler;
	210
	211	ret = register_kernel_hw_breakpoint(entry->ksym_hbp);
	212	if (ret < 0) {
	213	printk(KERN_INFO "ksym_tracer request failed. Try again"
	214	" later!!\n");
558df6c8 LZ	215	ret = -EAGAIN;
558df6c8 LZ	216	goto err;
0722db01 P	217	}
	218	hlist_add_head_rcu(&(entry->ksym_hlist), &ksym_filter_head);
	219	ksym_filter_entry_count++;
0722db01	220	return 0;
558df6c8 LZ	221	err:
	222	if (entry->ksym_hbp)
	223	kfree(entry->ksym_hbp->info.name);
	224	kfree(entry->ksym_hbp);
	225	kfree(entry);
	226	return ret;
0722db01 P	227	}
	228
	229	static ssize_t ksym_trace_filter_read(struct file filp, char __user ubuf,
	230	size_t count, loff_t *ppos)
	231	{
	232	struct trace_ksym *entry;
	233	struct hlist_node *node;
be9742e6 LZ	234	struct trace_seq *s;
	235	ssize_t cnt = 0;
	236	int ret;
	237
	238	s = kmalloc(sizeof(*s), GFP_KERNEL);
	239	if (!s)
	240	return -ENOMEM;
	241	trace_seq_init(s);
0722db01 P	242
	243	mutex_lock(&ksym_tracer_mutex);
	244
	245	hlist_for_each_entry(entry, node, &ksym_filter_head, ksym_hlist) {
be9742e6	246	ret = trace_seq_printf(s, "%s:", entry->ksym_hbp->info.name);
0722db01	247	if (entry->ksym_hbp->info.type == HW_BREAKPOINT_WRITE)
be9742e6	248	ret = trace_seq_puts(s, "-w-\n");
0722db01	249	else if (entry->ksym_hbp->info.type == HW_BREAKPOINT_RW)
be9742e6 LZ	250	ret = trace_seq_puts(s, "rw-\n");
be9742e6 LZ	251	WARN_ON_ONCE(!ret);
0722db01	252	}
be9742e6 LZ	253
	254	cnt = simple_read_from_buffer(ubuf, count, ppos, s->buffer, s->len);
	255
0722db01 P	256	mutex_unlock(&ksym_tracer_mutex);
0722db01 P	257
be9742e6 LZ	258	kfree(s);
	259
	260	return cnt;
0722db01 P	261	}
0722db01 P	262
75e33751 XG	263	static void __ksym_trace_reset(void)
	264	{
	265	struct trace_ksym *entry;
	266	struct hlist_node node, node1;
	267
	268	mutex_lock(&ksym_tracer_mutex);
	269	hlist_for_each_entry_safe(entry, node, node1, &ksym_filter_head,
	270	ksym_hlist) {
	271	unregister_kernel_hw_breakpoint(entry->ksym_hbp);
	272	ksym_filter_entry_count--;
	273	hlist_del_rcu(&(entry->ksym_hlist));
	274	synchronize_rcu();
	275	kfree(entry->ksym_hbp->info.name);
	276	kfree(entry->ksym_hbp);
	277	kfree(entry);
	278	}
	279	mutex_unlock(&ksym_tracer_mutex);
	280	}
	281
0722db01 P	282	static ssize_t ksym_trace_filter_write(struct file *file,
	283	const char __user *buffer,
	284	size_t count, loff_t *ppos)
	285	{
	286	struct trace_ksym *entry;
	287	struct hlist_node *node;
	288	char input_string, ksymname = NULL;
	289	unsigned long ksym_addr = 0;
	290	int ret, op, changed = 0;
	291
011ed568	292	input_string = kzalloc(count + 1, GFP_KERNEL);
0722db01 P	293	if (!input_string)
	294	return -ENOMEM;
	295
	296	if (copy_from_user(input_string, buffer, count)) {
	297	kfree(input_string);
	298	return -EFAULT;
	299	}
011ed568	300	input_string[count] = '\0';
0722db01	301
75e33751 XG	302	strstrip(input_string);
	303
	304	/*
	305	* Clear all breakpoints if:
	306	* 1: echo > ksym_trace_filter
	307	* 2: echo 0 > ksym_trace_filter
	308	* 3: echo "*:---" > ksym_trace_filter
	309	*/
	310	if (!input_string[0] \|\| !strcmp(input_string, "0") \|\|
	311	!strcmp(input_string, "*:---")) {
	312	__ksym_trace_reset();
	313	kfree(input_string);
	314	return count;
	315	}
	316
0722db01 P	317	ret = op = parse_ksym_trace_str(input_string, &ksymname, &ksym_addr);
	318	if (ret < 0) {
	319	kfree(input_string);
	320	return ret;
	321	}
	322
	323	mutex_lock(&ksym_tracer_mutex);
	324
	325	ret = -EINVAL;
	326	hlist_for_each_entry(entry, node, &ksym_filter_head, ksym_hlist) {
	327	if (entry->ksym_addr == ksym_addr) {
	328	/* Check for malformed request: (6) */
	329	if (entry->ksym_hbp->info.type != op)
	330	changed = 1;
	331	else
558df6c8	332	goto out;
0722db01 P	333	break;
	334	}
	335	}
	336	if (changed) {
	337	unregister_kernel_hw_breakpoint(entry->ksym_hbp);
	338	entry->ksym_hbp->info.type = op;
	339	if (op > 0) {
	340	ret = register_kernel_hw_breakpoint(entry->ksym_hbp);
558df6c8 LZ	341	if (ret == 0)
	342	goto out;
	343	}
0722db01 P	344	ksym_filter_entry_count--;
	345	hlist_del_rcu(&(entry->ksym_hlist));
	346	synchronize_rcu();
558df6c8	347	kfree(entry->ksym_hbp->info.name);
0722db01 P	348	kfree(entry->ksym_hbp);
0722db01 P	349	kfree(entry);
8e068542	350	ret = 0;
558df6c8	351	goto out;
0722db01 P	352	} else {
	353	/* Check for malformed request: (4) */
	354	if (op == 0)
558df6c8	355	goto out;
0722db01	356	ret = process_new_ksym_entry(ksymname, op, ksym_addr);
0722db01	357	}
558df6c8 LZ	358	out:
558df6c8 LZ	359	mutex_unlock(&ksym_tracer_mutex);
0722db01	360
0722db01 P	361	kfree(input_string);
0722db01 P	362
558df6c8 LZ	363	if (!ret)
558df6c8 LZ	364	ret = count;
0722db01 P	365	return ret;
	366	}
	367
	368	static const struct file_operations ksym_tracing_fops = {
	369	.open = tracing_open_generic,
	370	.read = ksym_trace_filter_read,
	371	.write = ksym_trace_filter_write,
	372	};
	373
	374	static void ksym_trace_reset(struct trace_array *tr)
	375	{
0722db01	376	ksym_tracing_enabled = 0;
75e33751	377	__ksym_trace_reset();
0722db01 P	378	}
	379
	380	static int ksym_trace_init(struct trace_array *tr)
	381	{
	382	int cpu, ret = 0;
	383
	384	for_each_online_cpu(cpu)
	385	tracing_reset(tr, cpu);
	386	ksym_tracing_enabled = 1;
	387	ksym_trace_array = tr;
	388
	389	return ret;
	390	}
	391
	392	static void ksym_trace_print_header(struct seq_file *m)
	393	{
0722db01	394	seq_puts(m,
d857ace1 XG	395	"# TASK-PID CPU# Symbol "
d857ace1 XG	396	"Type Function\n");
0722db01	397	seq_puts(m,
d857ace1 XG	398	"# \| \| \| "
d857ace1 XG	399	" \| \|\n");
0722db01 P	400	}
	401
	402	static enum print_line_t ksym_trace_output(struct trace_iterator *iter)
	403	{
	404	struct trace_entry *entry = iter->ent;
	405	struct trace_seq *s = &iter->seq;
db59504d	406	struct ksym_trace_entry *field;
0722db01 P	407	char str[KSYM_SYMBOL_LEN];
	408	int ret;
	409
	410	if (entry->type != TRACE_KSYM)
	411	return TRACE_TYPE_UNHANDLED;
	412
	413	trace_assign_type(field, entry);
	414
d857ace1	415	ret = trace_seq_printf(s, "%11s-%-5d [%03d] %-30s ", field->cmd,
0722db01 P	416	entry->pid, iter->cpu, field->ksym_name);
	417	if (!ret)
	418	return TRACE_TYPE_PARTIAL_LINE;
	419
db59504d	420	switch (field->type) {
0722db01 P	421	case HW_BREAKPOINT_WRITE:
	422	ret = trace_seq_printf(s, " W ");
	423	break;
	424	case HW_BREAKPOINT_RW:
	425	ret = trace_seq_printf(s, " RW ");
	426	break;
	427	default:
	428	return TRACE_TYPE_PARTIAL_LINE;
	429	}
	430
	431	if (!ret)
	432	return TRACE_TYPE_PARTIAL_LINE;
	433
	434	sprint_symbol(str, field->ip);
d857ace1	435	ret = trace_seq_printf(s, "%s\n", str);
0722db01 P	436	if (!ret)
	437	return TRACE_TYPE_PARTIAL_LINE;
	438
	439	return TRACE_TYPE_HANDLED;
	440	}
	441
	442	struct tracer ksym_tracer __read_mostly =
	443	{
	444	.name = "ksym_tracer",
	445	.init = ksym_trace_init,
	446	.reset = ksym_trace_reset,
	447	#ifdef CONFIG_FTRACE_SELFTEST
	448	.selftest = trace_selftest_startup_ksym,
	449	#endif
	450	.print_header = ksym_trace_print_header,
	451	.print_line = ksym_trace_output
	452	};
	453
	454	__init static int init_ksym_trace(void)
	455	{
	456	struct dentry *d_tracer;
	457	struct dentry *entry;
	458
	459	d_tracer = tracing_init_dentry();
	460	ksym_filter_entry_count = 0;
	461
	462	entry = debugfs_create_file("ksym_trace_filter", 0644, d_tracer,
	463	NULL, &ksym_tracing_fops);
	464	if (!entry)
	465	pr_warning("Could not create debugfs "
	466	"'ksym_trace_filter' file\n");
	467
	468	return register_tracer(&ksym_tracer);
	469	}
	470	device_initcall(init_ksym_trace);
	471
	472
	473	#ifdef CONFIG_PROFILE_KSYM_TRACER
	474	static int ksym_tracer_stat_headers(struct seq_file *m)
	475	{
9d7e9344 LZ	476	seq_puts(m, " Access Type ");
	477	seq_puts(m, " Symbol Counter\n");
	478	seq_puts(m, " ----------- ");
	479	seq_puts(m, " ------ -------\n");
0722db01 P	480	return 0;
	481	}
	482
	483	static int ksym_tracer_stat_show(struct seq_file m, void v)
	484	{
	485	struct hlist_node *stat = v;
	486	struct trace_ksym *entry;
	487	int access_type = 0;
	488	char fn_name[KSYM_NAME_LEN];
	489
	490	entry = hlist_entry(stat, struct trace_ksym, ksym_hlist);
	491
	492	if (entry->ksym_hbp)
	493	access_type = entry->ksym_hbp->info.type;
	494
	495	switch (access_type) {
	496	case HW_BREAKPOINT_WRITE:
9d7e9344	497	seq_puts(m, " W ");
0722db01 P	498	break;
0722db01 P	499	case HW_BREAKPOINT_RW:
9d7e9344	500	seq_puts(m, " RW ");
0722db01 P	501	break;
0722db01 P	502	default:
9d7e9344	503	seq_puts(m, " NA ");
0722db01 P	504	}
	505
	506	if (lookup_symbol_name(entry->ksym_addr, fn_name) >= 0)
9d7e9344	507	seq_printf(m, " %-36s", fn_name);
0722db01	508	else
9d7e9344 LZ	509	seq_printf(m, " %-36s", "<NA>");
9d7e9344 LZ	510	seq_printf(m, " %15lu\n", entry->counter);
0722db01	511
0722db01 P	512	return 0;
	513	}
	514
	515	static void ksym_tracer_stat_start(struct tracer_stat trace)
	516	{
9d7e9344	517	return ksym_filter_head.first;
0722db01 P	518	}
	519
	520	static void *
	521	ksym_tracer_stat_next(void *v, int idx)
	522	{
	523	struct hlist_node *stat = v;
	524
	525	return stat->next;
	526	}
	527
	528	static struct tracer_stat ksym_tracer_stats = {
	529	.name = "ksym_tracer",
	530	.stat_start = ksym_tracer_stat_start,
	531	.stat_next = ksym_tracer_stat_next,
	532	.stat_headers = ksym_tracer_stat_headers,
	533	.stat_show = ksym_tracer_stat_show
	534	};
	535
	536	__init static int ksym_tracer_stat_init(void)
	537	{
	538	int ret;
	539
	540	ret = register_stat_tracer(&ksym_tracer_stats);
	541	if (ret) {
	542	printk(KERN_WARNING "Warning: could not register "
	543	"ksym tracer stats\n");
	544	return 1;
	545	}
	546
	547	return 0;
	548	}
	549	fs_initcall(ksym_tracer_stat_init);
	550	#endif /* CONFIG_PROFILE_KSYM_TRACER */