summaryrefslogtreecommitdiff
path: root/tools/lib/bpf/bpf_prog_linfo.c
blob: 5c503096ef4349ee5a4e0dbec4c357ff40b0ada6 (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
// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
/* Copyright (c) 2018 Facebook */

#include <string.h>
#include <stdlib.h>
#include <linux/err.h>
#include <linux/bpf.h>
#include "libbpf.h"
#include "libbpf_internal.h"

struct bpf_prog_linfo {
	void *raw_linfo;
	void *raw_jited_linfo;
	__u32 *nr_jited_linfo_per_func;
	__u32 *jited_linfo_func_idx;
	__u32 nr_linfo;
	__u32 nr_jited_func;
	__u32 rec_size;
	__u32 jited_rec_size;
};

static int dissect_jited_func(struct bpf_prog_linfo *prog_linfo,
			      const __u64 *ksym_func, const __u32 *ksym_len)
{
	__u32 nr_jited_func, nr_linfo;
	const void *raw_jited_linfo;
	const __u64 *jited_linfo;
	__u64 last_jited_linfo;
	/*
	 * Index to raw_jited_linfo:
	 *      i: Index for searching the next ksym_func
	 * prev_i: Index to the last found ksym_func
	 */
	__u32 i, prev_i;
	__u32 f; /* Index to ksym_func */

	raw_jited_linfo = prog_linfo->raw_jited_linfo;
	jited_linfo = raw_jited_linfo;
	if (ksym_func[0] != *jited_linfo)
		goto errout;

	prog_linfo->jited_linfo_func_idx[0] = 0;
	nr_jited_func = prog_linfo->nr_jited_func;
	nr_linfo = prog_linfo->nr_linfo;

	for (prev_i = 0, i = 1, f = 1;
	     i < nr_linfo && f < nr_jited_func;
	     i++) {
		raw_jited_linfo += prog_linfo->jited_rec_size;
		last_jited_linfo = *jited_linfo;
		jited_linfo = raw_jited_linfo;

		if (ksym_func[f] == *jited_linfo) {
			prog_linfo->jited_linfo_func_idx[f] = i;

			/* Sanity check */
			if (last_jited_linfo - ksym_func[f - 1] + 1 >
			    ksym_len[f - 1])
				goto errout;

			prog_linfo->nr_jited_linfo_per_func[f - 1] =
				i - prev_i;
			prev_i = i;

			/*
			 * The ksym_func[f] is found in jited_linfo.
			 * Look for the next one.
			 */
			f++;
		} else if (*jited_linfo <= last_jited_linfo) {
			/* Ensure the addr is increasing _within_ a func */
			goto errout;
		}
	}

	if (f != nr_jited_func)
		goto errout;

	prog_linfo->nr_jited_linfo_per_func[nr_jited_func - 1] =
		nr_linfo - prev_i;

	return 0;

errout:
	return -EINVAL;
}

void bpf_prog_linfo__free(struct bpf_prog_linfo *prog_linfo)
{
	if (!prog_linfo)
		return;

	free(prog_linfo->raw_linfo);
	free(prog_linfo->raw_jited_linfo);
	free(prog_linfo->nr_jited_linfo_per_func);
	free(prog_linfo->jited_linfo_func_idx);
	free(prog_linfo);
}

struct bpf_prog_linfo *bpf_prog_linfo__new(const struct bpf_prog_info *info)
{
	struct bpf_prog_linfo *prog_linfo;
	__u32 nr_linfo, nr_jited_func;
	__u64 data_sz;

	nr_linfo = info->nr_line_info;

	if (!nr_linfo)
		return errno = EINVAL, NULL;

	/*
	 * The min size that bpf_prog_linfo has to access for
	 * searching purpose.
	 */
	if (info->line_info_rec_size <
	    offsetof(struct bpf_line_info, file_name_off))
		return errno = EINVAL, NULL;

	prog_linfo = calloc(1, sizeof(*prog_linfo));
	if (!prog_linfo)
		return errno = ENOMEM, NULL;

	/* Copy xlated line_info */
	prog_linfo->nr_linfo = nr_linfo;
	prog_linfo->rec_size = info->line_info_rec_size;
	data_sz = (__u64)nr_linfo * prog_linfo->rec_size;
	prog_linfo->raw_linfo = malloc(data_sz);
	if (!prog_linfo->raw_linfo)
		goto err_free;
	memcpy(prog_linfo->raw_linfo, (void *)(long)info->line_info, data_sz);

	nr_jited_func = info->nr_jited_ksyms;
	if (!nr_jited_func ||
	    !info->jited_line_info ||
	    info->nr_jited_line_info != nr_linfo ||
	    info->jited_line_info_rec_size < sizeof(__u64) ||
	    info->nr_jited_func_lens != nr_jited_func ||
	    !info->jited_ksyms ||
	    !info->jited_func_lens)
		/* Not enough info to provide jited_line_info */
		return prog_linfo;

	/* Copy jited_line_info */
	prog_linfo->nr_jited_func = nr_jited_func;
	prog_linfo->jited_rec_size = info->jited_line_info_rec_size;
	data_sz = (__u64)nr_linfo * prog_linfo->jited_rec_size;
	prog_linfo->raw_jited_linfo = malloc(data_sz);
	if (!prog_linfo->raw_jited_linfo)
		goto err_free;
	memcpy(prog_linfo->raw_jited_linfo,
	       (void *)(long)info->jited_line_info, data_sz);

	/* Number of jited_line_info per jited func */
	prog_linfo->nr_jited_linfo_per_func = malloc(nr_jited_func *
						     sizeof(__u32));
	if (!prog_linfo->nr_jited_linfo_per_func)
		goto err_free;

	/*
	 * For each jited func,
	 * the start idx to the "linfo" and "jited_linfo" array,
	 */
	prog_linfo->jited_linfo_func_idx = malloc(nr_jited_func *
						  sizeof(__u32));
	if (!prog_linfo->jited_linfo_func_idx)
		goto err_free;

	if (dissect_jited_func(prog_linfo,
			       (__u64 *)(long)info->jited_ksyms,
			       (__u32 *)(long)info->jited_func_lens))
		goto err_free;

	return prog_linfo;

err_free:
	bpf_prog_linfo__free(prog_linfo);
	return errno = EINVAL, NULL;
}

const struct bpf_line_info *
bpf_prog_linfo__lfind_addr_func(const struct bpf_prog_linfo *prog_linfo,
				__u64 addr, __u32 func_idx, __u32 nr_skip)
{
	__u32 jited_rec_size, rec_size, nr_linfo, start, i;
	const void *raw_jited_linfo, *raw_linfo;
	const __u64 *jited_linfo;

	if (func_idx >= prog_linfo->nr_jited_func)
		return errno = ENOENT, NULL;

	nr_linfo = prog_linfo->nr_jited_linfo_per_func[func_idx];
	if (nr_skip >= nr_linfo)
		return errno = ENOENT, NULL;

	start = prog_linfo->jited_linfo_func_idx[func_idx] + nr_skip;
	jited_rec_size = prog_linfo->jited_rec_size;
	raw_jited_linfo = prog_linfo->raw_jited_linfo +
		(start * jited_rec_size);
	jited_linfo = raw_jited_linfo;
	if (addr < *jited_linfo)
		return errno = ENOENT, NULL;

	nr_linfo -= nr_skip;
	rec_size = prog_linfo->rec_size;
	raw_linfo = prog_linfo->raw_linfo + (start * rec_size);
	for (i = 0; i < nr_linfo; i++) {
		if (addr < *jited_linfo)
			break;

		raw_linfo += rec_size;
		raw_jited_linfo += jited_rec_size;
		jited_linfo = raw_jited_linfo;
	}

	return raw_linfo - rec_size;
}

const struct bpf_line_info *
bpf_prog_linfo__lfind(const struct bpf_prog_linfo *prog_linfo,
		      __u32 insn_off, __u32 nr_skip)
{
	const struct bpf_line_info *linfo;
	__u32 rec_size, nr_linfo, i;
	const void *raw_linfo;

	nr_linfo = prog_linfo->nr_linfo;
	if (nr_skip >= nr_linfo)
		return errno = ENOENT, NULL;

	rec_size = prog_linfo->rec_size;
	raw_linfo = prog_linfo->raw_linfo + (nr_skip * rec_size);
	linfo = raw_linfo;
	if (insn_off < linfo->insn_off)
		return errno = ENOENT, NULL;

	nr_linfo -= nr_skip;
	for (i = 0; i < nr_linfo; i++) {
		if (insn_off < linfo->insn_off)
			break;

		raw_linfo += rec_size;
		linfo = raw_linfo;
	}

	return raw_linfo - rec_size;
}