[mirror_ubuntu-bionic-kernel.git] / kernel / trace / trace_output.c

/*
 * trace_output.c
 *
 * Copyright (C) 2008 Red Hat Inc, Steven Rostedt <srostedt@redhat.com>
 *
 */

#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/ftrace.h>

#include "trace_output.h"

/* must be a power of 2 */
#define EVENT_HASHSIZE	128

static DEFINE_MUTEX(trace_event_mutex);
static struct hlist_head event_hash[EVENT_HASHSIZE] __read_mostly;

static int next_event_type = __TRACE_LAST_TYPE + 1;

/**
 * trace_seq_printf - sequence printing of trace information
 * @s: trace sequence descriptor
 * @fmt: printf format string
 *
 * The tracer may use either sequence operations or its own
 * copy to user routines. To simplify formating of a trace
 * trace_seq_printf is used to store strings into a special
 * buffer (@s). Then the output may be either used by
 * the sequencer or pulled into another buffer.
 */
int
trace_seq_printf(struct trace_seq *s, const char *fmt, ...)
{
	int len = (PAGE_SIZE - 1) - s->len;
	va_list ap;
	int ret;

	if (!len)
		return 0;

	va_start(ap, fmt);
	ret = vsnprintf(s->buffer + s->len, len, fmt, ap);
	va_end(ap);

	/* If we can't write it all, don't bother writing anything */
	if (ret >= len)
		return 0;

	s->len += ret;

	return len;
}

/**
 * trace_seq_puts - trace sequence printing of simple string
 * @s: trace sequence descriptor
 * @str: simple string to record
 *
 * The tracer may use either the sequence operations or its own
 * copy to user routines. This function records a simple string
 * into a special buffer (@s) for later retrieval by a sequencer
 * or other mechanism.
 */
int trace_seq_puts(struct trace_seq *s, const char *str)
{
	int len = strlen(str);

	if (len > ((PAGE_SIZE - 1) - s->len))
		return 0;

	memcpy(s->buffer + s->len, str, len);
	s->len += len;

	return len;
}

int trace_seq_putc(struct trace_seq *s, unsigned char c)
{
	if (s->len >= (PAGE_SIZE - 1))
		return 0;

	s->buffer[s->len++] = c;

	return 1;
}

int trace_seq_putmem(struct trace_seq *s, void *mem, size_t len)
{
	if (len > ((PAGE_SIZE - 1) - s->len))
		return 0;

	memcpy(s->buffer + s->len, mem, len);
	s->len += len;

	return len;
}

int trace_seq_putmem_hex(struct trace_seq *s, void *mem, size_t len)
{
	unsigned char hex[HEX_CHARS];
	unsigned char *data = mem;
	int i, j;

#ifdef __BIG_ENDIAN
	for (i = 0, j = 0; i < len; i++) {
#else
	for (i = len-1, j = 0; i >= 0; i--) {
#endif
		hex[j++] = hex_asc_hi(data[i]);
		hex[j++] = hex_asc_lo(data[i]);
	}
	hex[j++] = ' ';

	return trace_seq_putmem(s, hex, j);
}

int trace_seq_path(struct trace_seq *s, struct path *path)
{
	unsigned char *p;

	if (s->len >= (PAGE_SIZE - 1))
		return 0;
	p = d_path(path, s->buffer + s->len, PAGE_SIZE - s->len);
	if (!IS_ERR(p)) {
		p = mangle_path(s->buffer + s->len, p, "\n");
		if (p) {
			s->len = p - s->buffer;
			return 1;
		}
	} else {
		s->buffer[s->len++] = '?';
		return 1;
	}

	return 0;
}

#ifdef CONFIG_KRETPROBES
static inline const char *kretprobed(const char *name)
{
	static const char tramp_name[] = "kretprobe_trampoline";
	int size = sizeof(tramp_name);

	if (strncmp(tramp_name, name, size) == 0)
		return "[unknown/kretprobe'd]";
	return name;
}
#else
static inline const char *kretprobed(const char *name)
{
	return name;
}
#endif /* CONFIG_KRETPROBES */

static int
seq_print_sym_short(struct trace_seq *s, const char *fmt, unsigned long address)
{
#ifdef CONFIG_KALLSYMS
	char str[KSYM_SYMBOL_LEN];
	const char *name;

	kallsyms_lookup(address, NULL, NULL, NULL, str);

	name = kretprobed(str);

	return trace_seq_printf(s, fmt, name);
#endif
	return 1;
}

static int
seq_print_sym_offset(struct trace_seq *s, const char *fmt,
		     unsigned long address)
{
#ifdef CONFIG_KALLSYMS
	char str[KSYM_SYMBOL_LEN];
	const char *name;

	sprint_symbol(str, address);
	name = kretprobed(str);

	return trace_seq_printf(s, fmt, name);
#endif
	return 1;
}

#ifndef CONFIG_64BIT
# define IP_FMT "%08lx"
#else
# define IP_FMT "%016lx"
#endif

int seq_print_user_ip(struct trace_seq *s, struct mm_struct *mm,
		      unsigned long ip, unsigned long sym_flags)
{
	struct file *file = NULL;
	unsigned long vmstart = 0;
	int ret = 1;

	if (mm) {
		const struct vm_area_struct *vma;

		down_read(&mm->mmap_sem);
		vma = find_vma(mm, ip);
		if (vma) {
			file = vma->vm_file;
			vmstart = vma->vm_start;
		}
		if (file) {
			ret = trace_seq_path(s, &file->f_path);
			if (ret)
				ret = trace_seq_printf(s, "[+0x%lx]",
						       ip - vmstart);
		}
		up_read(&mm->mmap_sem);
	}
	if (ret && ((sym_flags & TRACE_ITER_SYM_ADDR) || !file))
		ret = trace_seq_printf(s, " <" IP_FMT ">", ip);
	return ret;
}

int
seq_print_userip_objs(const struct userstack_entry *entry, struct trace_seq *s,
		      unsigned long sym_flags)
{
	struct mm_struct *mm = NULL;
	int ret = 1;
	unsigned int i;

	if (trace_flags & TRACE_ITER_SYM_USEROBJ) {
		struct task_struct *task;
		/*
		 * we do the lookup on the thread group leader,
		 * since individual threads might have already quit!
		 */
		rcu_read_lock();
		task = find_task_by_vpid(entry->ent.tgid);
		if (task)
			mm = get_task_mm(task);
		rcu_read_unlock();
	}

	for (i = 0; i < FTRACE_STACK_ENTRIES; i++) {
		unsigned long ip = entry->caller[i];

		if (ip == ULONG_MAX || !ret)
			break;
		if (i && ret)
			ret = trace_seq_puts(s, " <- ");
		if (!ip) {
			if (ret)
				ret = trace_seq_puts(s, "??");
			continue;
		}
		if (!ret)
			break;
		if (ret)
			ret = seq_print_user_ip(s, mm, ip, sym_flags);
	}

	if (mm)
		mmput(mm);
	return ret;
}

int
seq_print_ip_sym(struct trace_seq *s, unsigned long ip, unsigned long sym_flags)
{
	int ret;

	if (!ip)
		return trace_seq_printf(s, "0");

	if (sym_flags & TRACE_ITER_SYM_OFFSET)
		ret = seq_print_sym_offset(s, "%s", ip);
	else
		ret = seq_print_sym_short(s, "%s", ip);

	if (!ret)
		return 0;

	if (sym_flags & TRACE_ITER_SYM_ADDR)
		ret = trace_seq_printf(s, " <" IP_FMT ">", ip);
	return ret;
}

/**
 * ftrace_find_event - find a registered event
 * @type: the type of event to look for
 *
 * Returns an event of type @type otherwise NULL
 */
struct trace_event *ftrace_find_event(int type)
{
	struct trace_event *event;
	struct hlist_node *n;
	unsigned key;

	key = type & (EVENT_HASHSIZE - 1);

	hlist_for_each_entry_rcu(event, n, &event_hash[key], node) {
		if (event->type == type)
			return event;
	}

	return NULL;
}

/**
 * register_ftrace_event - register output for an event type
 * @event: the event type to register
 *
 * Event types are stored in a hash and this hash is used to
 * find a way to print an event. If the @event->type is set
 * then it will use that type, otherwise it will assign a
 * type to use.
 *
 * If you assign your own type, please make sure it is added
 * to the trace_type enum in trace.h, to avoid collisions
 * with the dynamic types.
 *
 * Returns the event type number or zero on error.
 */
int register_ftrace_event(struct trace_event *event)
{
	unsigned key;
	int ret = 0;

	mutex_lock(&trace_event_mutex);

	if (!event->type)
		event->type = next_event_type++;
	else if (event->type > __TRACE_LAST_TYPE) {
		printk(KERN_WARNING "Need to add type to trace.h\n");
		WARN_ON(1);
	}

	if (ftrace_find_event(event->type))
		goto out;

	key = event->type & (EVENT_HASHSIZE - 1);

	hlist_add_head_rcu(&event->node, &event_hash[key]);

	ret = event->type;
 out:
	mutex_unlock(&trace_event_mutex);

	return ret;
}

/**
 * unregister_ftrace_event - remove a no longer used event
 * @event: the event to remove
 */
int unregister_ftrace_event(struct trace_event *event)
{
	mutex_lock(&trace_event_mutex);
	hlist_del(&event->node);
	mutex_unlock(&trace_event_mutex);

	return 0;
}
Commit	Line	Data
f0868d1e SR	1	/*
	2	* trace_output.c
	3	*
	4	* Copyright (C) 2008 Red Hat Inc, Steven Rostedt <srostedt@redhat.com>
	5	*
	6	*/
	7
	8	#include <linux/module.h>
	9	#include <linux/mutex.h>
	10	#include <linux/ftrace.h>
	11
	12	#include "trace_output.h"
	13
	14	/* must be a power of 2 */
	15	#define EVENT_HASHSIZE 128
	16
	17	static DEFINE_MUTEX(trace_event_mutex);
	18	static struct hlist_head event_hash[EVENT_HASHSIZE] __read_mostly;
	19
	20	static int next_event_type = __TRACE_LAST_TYPE + 1;
	21
	22	/**
	23	* trace_seq_printf - sequence printing of trace information
	24	* @s: trace sequence descriptor
	25	* @fmt: printf format string
	26	*
	27	* The tracer may use either sequence operations or its own
	28	* copy to user routines. To simplify formating of a trace
	29	* trace_seq_printf is used to store strings into a special
	30	* buffer (@s). Then the output may be either used by
	31	* the sequencer or pulled into another buffer.
	32	*/
	33	int
	34	trace_seq_printf(struct trace_seq s, const char fmt, ...)
	35	{
	36	int len = (PAGE_SIZE - 1) - s->len;
	37	va_list ap;
	38	int ret;
	39
	40	if (!len)
	41	return 0;
	42
	43	va_start(ap, fmt);
	44	ret = vsnprintf(s->buffer + s->len, len, fmt, ap);
	45	va_end(ap);
	46
	47	/* If we can't write it all, don't bother writing anything */
	48	if (ret >= len)
	49	return 0;
	50
	51	s->len += ret;
	52
	53	return len;
	54	}
	55
	56	/**
	57	* trace_seq_puts - trace sequence printing of simple string
	58	* @s: trace sequence descriptor
	59	* @str: simple string to record
	60	*
	61	* The tracer may use either the sequence operations or its own
	62	* copy to user routines. This function records a simple string
	63	* into a special buffer (@s) for later retrieval by a sequencer
	64	* or other mechanism.
65	*/
66	int trace_seq_puts(struct trace_seq s, const char str)
67	{
68	int len = strlen(str);
69
70	if (len > ((PAGE_SIZE - 1) - s->len))
71	return 0;
72
73	memcpy(s->buffer + s->len, str, len);
74	s->len += len;
75
76	return len;
77	}
78
79	int trace_seq_putc(struct trace_seq *s, unsigned char c)
80	{
81	if (s->len >= (PAGE_SIZE - 1))
82	return 0;
83
84	s->buffer[s->len++] = c;
85
86	return 1;
87	}
88
89	int trace_seq_putmem(struct trace_seq s, void mem, size_t len)
90	{
91	if (len > ((PAGE_SIZE - 1) - s->len))
92	return 0;
93
94	memcpy(s->buffer + s->len, mem, len);
95	s->len += len;
96
97	return len;
98	}
99
100	int trace_seq_putmem_hex(struct trace_seq s, void mem, size_t len)
101	{
102	unsigned char hex[HEX_CHARS];
103	unsigned char *data = mem;
104	int i, j;
105
106	#ifdef __BIG_ENDIAN
107	for (i = 0, j = 0; i < len; i++) {
108	#else
109	for (i = len-1, j = 0; i >= 0; i--) {
110	#endif
111	hex[j++] = hex_asc_hi(data[i]);
112	hex[j++] = hex_asc_lo(data[i]);
113	}
114	hex[j++] = ' ';
115
116	return trace_seq_putmem(s, hex, j);
117	}
118
119	int trace_seq_path(struct trace_seq s, struct path path)
120	{
121	unsigned char *p;
122
123	if (s->len >= (PAGE_SIZE - 1))
124	return 0;
125	p = d_path(path, s->buffer + s->len, PAGE_SIZE - s->len);
126	if (!IS_ERR(p)) {
127	p = mangle_path(s->buffer + s->len, p, "\n");
128	if (p) {
129	s->len = p - s->buffer;
130	return 1;
131	}
132	} else {
133	s->buffer[s->len++] = '?';
134	return 1;
135	}
136
137	return 0;
138	}
139
140	#ifdef CONFIG_KRETPROBES
141	static inline const char kretprobed(const char name)
142	{
143	static const char tramp_name[] = "kretprobe_trampoline";
144	int size = sizeof(tramp_name);
145
146	if (strncmp(tramp_name, name, size) == 0)
147	return "[unknown/kretprobe'd]";
148	return name;
149	}
150	#else
151	static inline const char kretprobed(const char name)
152	{
153	return name;
154	}
155	#endif /* CONFIG_KRETPROBES */
156
157	static int
158	seq_print_sym_short(struct trace_seq s, const char fmt, unsigned long address)
159	{
160	#ifdef CONFIG_KALLSYMS
161	char str[KSYM_SYMBOL_LEN];
162	const char *name;
163
164	kallsyms_lookup(address, NULL, NULL, NULL, str);
165
166	name = kretprobed(str);
167
168	return trace_seq_printf(s, fmt, name);
169	#endif
170	return 1;
171	}
172
173	static int
174	seq_print_sym_offset(struct trace_seq s, const char fmt,
175	unsigned long address)
176	{
177	#ifdef CONFIG_KALLSYMS
178	char str[KSYM_SYMBOL_LEN];
179	const char *name;
180
181	sprint_symbol(str, address);
182	name = kretprobed(str);
183
184	return trace_seq_printf(s, fmt, name);
185	#endif
186	return 1;
187	}
188
189	#ifndef CONFIG_64BIT
190	# define IP_FMT "%08lx"
191	#else
192	# define IP_FMT "%016lx"
193	#endif
194
195	int seq_print_user_ip(struct trace_seq s, struct mm_struct mm,
196	unsigned long ip, unsigned long sym_flags)
197	{
198	struct file *file = NULL;
199	unsigned long vmstart = 0;
200	int ret = 1;
201
202	if (mm) {
203	const struct vm_area_struct *vma;
204
205	down_read(&mm->mmap_sem);
206	vma = find_vma(mm, ip);
207	if (vma) {
208	file = vma->vm_file;
209	vmstart = vma->vm_start;
210	}
211	if (file) {
212	ret = trace_seq_path(s, &file->f_path);
213	if (ret)
214	ret = trace_seq_printf(s, "[+0x%lx]",
215	ip - vmstart);
216	}
217	up_read(&mm->mmap_sem);
218	}
219	if (ret && ((sym_flags & TRACE_ITER_SYM_ADDR) \|\| !file))
220	ret = trace_seq_printf(s, " <" IP_FMT ">", ip);
221	return ret;
222	}
223
224	int
225	seq_print_userip_objs(const struct userstack_entry entry, struct trace_seq s,
226	unsigned long sym_flags)
227	{
228	struct mm_struct *mm = NULL;
229	int ret = 1;
230	unsigned int i;
231
232	if (trace_flags & TRACE_ITER_SYM_USEROBJ) {
233	struct task_struct *task;
234	/*
235	* we do the lookup on the thread group leader,
236	* since individual threads might have already quit!
237	*/
238	rcu_read_lock();
239	task = find_task_by_vpid(entry->ent.tgid);
240	if (task)
241	mm = get_task_mm(task);
242	rcu_read_unlock();
243	}
244
245	for (i = 0; i < FTRACE_STACK_ENTRIES; i++) {
246	unsigned long ip = entry->caller[i];
247
248	if (ip == ULONG_MAX \|\| !ret)
249	break;
250	if (i && ret)
251	ret = trace_seq_puts(s, " <- ");
252	if (!ip) {
253	if (ret)
254	ret = trace_seq_puts(s, "??");
255	continue;
256	}
257	if (!ret)
258	break;
259	if (ret)
260	ret = seq_print_user_ip(s, mm, ip, sym_flags);
261	}
262
263	if (mm)
264	mmput(mm);
265	return ret;
266	}
267
268	int
269	seq_print_ip_sym(struct trace_seq *s, unsigned long ip, unsigned long sym_flags)
270	{
271	int ret;
272
273	if (!ip)
274	return trace_seq_printf(s, "0");
275
276	if (sym_flags & TRACE_ITER_SYM_OFFSET)
277	ret = seq_print_sym_offset(s, "%s", ip);
278	else
279	ret = seq_print_sym_short(s, "%s", ip);
280
281	if (!ret)
282	return 0;
283
284	if (sym_flags & TRACE_ITER_SYM_ADDR)
285	ret = trace_seq_printf(s, " <" IP_FMT ">", ip);
286	return ret;
287	}
288
289	/**
290	* ftrace_find_event - find a registered event
291	* @type: the type of event to look for
292	*
293	* Returns an event of type @type otherwise NULL
294	*/
295	struct trace_event *ftrace_find_event(int type)
296	{
297	struct trace_event *event;
298	struct hlist_node *n;
299	unsigned key;
300
301	key = type & (EVENT_HASHSIZE - 1);
302
303	hlist_for_each_entry_rcu(event, n, &event_hash[key], node) {
304	if (event->type == type)
305	return event;
306	}
307
308	return NULL;
309	}
310
311	/**
312	* register_ftrace_event - register output for an event type
313	* @event: the event type to register
314	*
315	* Event types are stored in a hash and this hash is used to
316	* find a way to print an event. If the @event->type is set
317	* then it will use that type, otherwise it will assign a
318	* type to use.
319	*
320	* If you assign your own type, please make sure it is added
321	* to the trace_type enum in trace.h, to avoid collisions
322	* with the dynamic types.
323	*
324	* Returns the event type number or zero on error.
325	*/
326	int register_ftrace_event(struct trace_event *event)
327	{
328	unsigned key;
329	int ret = 0;
330
331	mutex_lock(&trace_event_mutex);
332
333	if (!event->type)
334	event->type = next_event_type++;
335	else if (event->type > __TRACE_LAST_TYPE) {
336	printk(KERN_WARNING "Need to add type to trace.h\n");
337	WARN_ON(1);
338	}
339
340	if (ftrace_find_event(event->type))
341	goto out;
342
343	key = event->type & (EVENT_HASHSIZE - 1);
344
345	hlist_add_head_rcu(&event->node, &event_hash[key]);
346
347	ret = event->type;
348	out:
349	mutex_unlock(&trace_event_mutex);
350
351	return ret;
352	}
353
354	/**
355	* unregister_ftrace_event - remove a no longer used event
356	* @event: the event to remove
357	*/
358	int unregister_ftrace_event(struct trace_event *event)
359	{
360	mutex_lock(&trace_event_mutex);
361	hlist_del(&event->node);
362	mutex_unlock(&trace_event_mutex);
363
364	return 0;
365	}