summaryrefslogtreecommitdiff
path: root/kernel/trace/fprobe.c
blob: 8b2dd5b9dcd142e136643584bdb7d54445d951de (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
// SPDX-License-Identifier: GPL-2.0
/*
 * fprobe - Simple ftrace probe wrapper for function entry.
 */
#define pr_fmt(fmt) "fprobe: " fmt

#include <linux/err.h>
#include <linux/fprobe.h>
#include <linux/kallsyms.h>
#include <linux/kprobes.h>
#include <linux/rethook.h>
#include <linux/slab.h>
#include <linux/sort.h>

#include "trace.h"

struct fprobe_rethook_node {
	struct rethook_node node;
	unsigned long entry_ip;
};

static void fprobe_handler(unsigned long ip, unsigned long parent_ip,
			   struct ftrace_ops *ops, struct ftrace_regs *fregs)
{
	struct fprobe_rethook_node *fpr;
	struct rethook_node *rh;
	struct fprobe *fp;
	int bit;

	fp = container_of(ops, struct fprobe, ops);
	if (fprobe_disabled(fp))
		return;

	bit = ftrace_test_recursion_trylock(ip, parent_ip);
	if (bit < 0) {
		fp->nmissed++;
		return;
	}

	if (fp->entry_handler)
		fp->entry_handler(fp, ip, ftrace_get_regs(fregs));

	if (fp->exit_handler) {
		rh = rethook_try_get(fp->rethook);
		if (!rh) {
			fp->nmissed++;
			goto out;
		}
		fpr = container_of(rh, struct fprobe_rethook_node, node);
		fpr->entry_ip = ip;
		rethook_hook(rh, ftrace_get_regs(fregs), true);
	}

out:
	ftrace_test_recursion_unlock(bit);
}
NOKPROBE_SYMBOL(fprobe_handler);

static void fprobe_kprobe_handler(unsigned long ip, unsigned long parent_ip,
				  struct ftrace_ops *ops, struct ftrace_regs *fregs)
{
	struct fprobe *fp = container_of(ops, struct fprobe, ops);

	if (unlikely(kprobe_running())) {
		fp->nmissed++;
		return;
	}
	kprobe_busy_begin();
	fprobe_handler(ip, parent_ip, ops, fregs);
	kprobe_busy_end();
}

static void fprobe_exit_handler(struct rethook_node *rh, void *data,
				struct pt_regs *regs)
{
	struct fprobe *fp = (struct fprobe *)data;
	struct fprobe_rethook_node *fpr;

	if (!fp || fprobe_disabled(fp))
		return;

	fpr = container_of(rh, struct fprobe_rethook_node, node);

	fp->exit_handler(fp, fpr->entry_ip, regs);
}
NOKPROBE_SYMBOL(fprobe_exit_handler);

/* Convert ftrace location address from symbols */
static unsigned long *get_ftrace_locations(const char **syms, int num)
{
	unsigned long addr, size;
	unsigned long *addrs;
	int i;

	/* Convert symbols to symbol address */
	addrs = kcalloc(num, sizeof(*addrs), GFP_KERNEL);
	if (!addrs)
		return ERR_PTR(-ENOMEM);

	for (i = 0; i < num; i++) {
		addr = kallsyms_lookup_name(syms[i]);
		if (!addr)	/* Maybe wrong symbol */
			goto error;

		/* Convert symbol address to ftrace location. */
		if (!kallsyms_lookup_size_offset(addr, &size, NULL) || !size)
			goto error;

		addr = ftrace_location_range(addr, addr + size - 1);
		if (!addr) /* No dynamic ftrace there. */
			goto error;

		addrs[i] = addr;
	}

	return addrs;

error:
	kfree(addrs);

	return ERR_PTR(-ENOENT);
}

static void fprobe_init(struct fprobe *fp)
{
	fp->nmissed = 0;
	if (fprobe_shared_with_kprobes(fp))
		fp->ops.func = fprobe_kprobe_handler;
	else
		fp->ops.func = fprobe_handler;
	fp->ops.flags |= FTRACE_OPS_FL_SAVE_REGS;
}

static int fprobe_init_rethook(struct fprobe *fp, int num)
{
	int i, size;

	if (num < 0)
		return -EINVAL;

	if (!fp->exit_handler) {
		fp->rethook = NULL;
		return 0;
	}

	/* Initialize rethook if needed */
	size = num * num_possible_cpus() * 2;
	if (size < 0)
		return -E2BIG;

	fp->rethook = rethook_alloc((void *)fp, fprobe_exit_handler);
	for (i = 0; i < size; i++) {
		struct rethook_node *node;

		node = kzalloc(sizeof(struct fprobe_rethook_node), GFP_KERNEL);
		if (!node) {
			rethook_free(fp->rethook);
			fp->rethook = NULL;
			return -ENOMEM;
		}
		rethook_add_node(fp->rethook, node);
	}
	return 0;
}

static void fprobe_fail_cleanup(struct fprobe *fp)
{
	if (fp->rethook) {
		/* Don't need to cleanup rethook->handler because this is not used. */
		rethook_free(fp->rethook);
		fp->rethook = NULL;
	}
	ftrace_free_filter(&fp->ops);
}

/**
 * register_fprobe() - Register fprobe to ftrace by pattern.
 * @fp: A fprobe data structure to be registered.
 * @filter: A wildcard pattern of probed symbols.
 * @notfilter: A wildcard pattern of NOT probed symbols.
 *
 * Register @fp to ftrace for enabling the probe on the symbols matched to @filter.
 * If @notfilter is not NULL, the symbols matched the @notfilter are not probed.
 *
 * Return 0 if @fp is registered successfully, -errno if not.
 */
int register_fprobe(struct fprobe *fp, const char *filter, const char *notfilter)
{
	struct ftrace_hash *hash;
	unsigned char *str;
	int ret, len;

	if (!fp || !filter)
		return -EINVAL;

	fprobe_init(fp);

	len = strlen(filter);
	str = kstrdup(filter, GFP_KERNEL);
	ret = ftrace_set_filter(&fp->ops, str, len, 0);
	kfree(str);
	if (ret)
		return ret;

	if (notfilter) {
		len = strlen(notfilter);
		str = kstrdup(notfilter, GFP_KERNEL);
		ret = ftrace_set_notrace(&fp->ops, str, len, 0);
		kfree(str);
		if (ret)
			goto out;
	}

	/* TODO:
	 * correctly calculate the total number of filtered symbols
	 * from both filter and notfilter.
	 */
	hash = fp->ops.local_hash.filter_hash;
	if (WARN_ON_ONCE(!hash))
		goto out;

	ret = fprobe_init_rethook(fp, (int)hash->count);
	if (!ret)
		ret = register_ftrace_function(&fp->ops);

out:
	if (ret)
		fprobe_fail_cleanup(fp);
	return ret;
}
EXPORT_SYMBOL_GPL(register_fprobe);

/**
 * register_fprobe_ips() - Register fprobe to ftrace by address.
 * @fp: A fprobe data structure to be registered.
 * @addrs: An array of target ftrace location addresses.
 * @num: The number of entries of @addrs.
 *
 * Register @fp to ftrace for enabling the probe on the address given by @addrs.
 * The @addrs must be the addresses of ftrace location address, which may be
 * the symbol address + arch-dependent offset.
 * If you unsure what this mean, please use other registration functions.
 *
 * Return 0 if @fp is registered successfully, -errno if not.
 */
int register_fprobe_ips(struct fprobe *fp, unsigned long *addrs, int num)
{
	int ret;

	if (!fp || !addrs || num <= 0)
		return -EINVAL;

	fprobe_init(fp);

	ret = ftrace_set_filter_ips(&fp->ops, addrs, num, 0, 0);
	if (ret)
		return ret;

	ret = fprobe_init_rethook(fp, num);
	if (!ret)
		ret = register_ftrace_function(&fp->ops);

	if (ret)
		fprobe_fail_cleanup(fp);
	return ret;
}
EXPORT_SYMBOL_GPL(register_fprobe_ips);

/**
 * register_fprobe_syms() - Register fprobe to ftrace by symbols.
 * @fp: A fprobe data structure to be registered.
 * @syms: An array of target symbols.
 * @num: The number of entries of @syms.
 *
 * Register @fp to the symbols given by @syms array. This will be useful if
 * you are sure the symbols exist in the kernel.
 *
 * Return 0 if @fp is registered successfully, -errno if not.
 */
int register_fprobe_syms(struct fprobe *fp, const char **syms, int num)
{
	unsigned long *addrs;
	int ret;

	if (!fp || !syms || num <= 0)
		return -EINVAL;

	addrs = get_ftrace_locations(syms, num);
	if (IS_ERR(addrs))
		return PTR_ERR(addrs);

	ret = register_fprobe_ips(fp, addrs, num);

	kfree(addrs);

	return ret;
}
EXPORT_SYMBOL_GPL(register_fprobe_syms);

/**
 * unregister_fprobe() - Unregister fprobe from ftrace
 * @fp: A fprobe data structure to be unregistered.
 *
 * Unregister fprobe (and remove ftrace hooks from the function entries).
 *
 * Return 0 if @fp is unregistered successfully, -errno if not.
 */
int unregister_fprobe(struct fprobe *fp)
{
	int ret;

	if (!fp || fp->ops.func != fprobe_handler)
		return -EINVAL;

	/*
	 * rethook_free() starts disabling the rethook, but the rethook handlers
	 * may be running on other processors at this point. To make sure that all
	 * current running handlers are finished, call unregister_ftrace_function()
	 * after this.
	 */
	if (fp->rethook)
		rethook_free(fp->rethook);

	ret = unregister_ftrace_function(&fp->ops);
	if (ret < 0)
		return ret;

	ftrace_free_filter(&fp->ops);

	return ret;
}
EXPORT_SYMBOL_GPL(unregister_fprobe);