FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_ctf.c
1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3 *
4 * Copyright (c) 2008 John Birrell <jb@freebsd.org>
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 *
28 * $FreeBSD: releng/12.0/sys/kern/kern_ctf.c 328218 2018-01-21 15:42:36Z pfg $
29 */
30
31 /*
32 * Note this file is included by both link_elf.c and link_elf_obj.c.
33 *
34 * The CTF header structure definition can't be used here because it's
35 * (annoyingly) covered by the CDDL. We will just use a few bytes from
36 * it as an integer array where we 'know' what they mean.
37 */
38 #define CTF_HDR_SIZE 36
39 #define CTF_HDR_STRTAB_U32 7
40 #define CTF_HDR_STRLEN_U32 8
41
42 #ifdef DDB_CTF
43 static void *
44 z_alloc(void *nil, u_int items, u_int size)
45 {
46 void *ptr;
47
48 ptr = malloc(items * size, M_TEMP, M_NOWAIT);
49 return ptr;
50 }
51
52 static void
53 z_free(void *nil, void *ptr)
54 {
55 free(ptr, M_TEMP);
56 }
57
58 #endif
59
60 static int
61 link_elf_ctf_get(linker_file_t lf, linker_ctf_t *lc)
62 {
63 #ifdef DDB_CTF
64 Elf_Ehdr *hdr = NULL;
65 Elf_Shdr *shdr = NULL;
66 caddr_t ctftab = NULL;
67 caddr_t raw = NULL;
68 caddr_t shstrtab = NULL;
69 elf_file_t ef = (elf_file_t) lf;
70 int flags;
71 int i;
72 int nbytes;
73 size_t sz;
74 struct nameidata nd;
75 struct thread *td = curthread;
76 uint8_t ctf_hdr[CTF_HDR_SIZE];
77 #endif
78 int error = 0;
79
80 if (lf == NULL || lc == NULL)
81 return (EINVAL);
82
83 /* Set the defaults for no CTF present. That's not a crime! */
84 bzero(lc, sizeof(*lc));
85
86 #ifdef DDB_CTF
87 /*
88 * First check if we've tried to load CTF data previously and the
89 * CTF ELF section wasn't found. We flag that condition by setting
90 * ctfcnt to -1. See below.
91 */
92 if (ef->ctfcnt < 0)
93 return (EFTYPE);
94
95 /* Now check if we've already loaded the CTF data.. */
96 if (ef->ctfcnt > 0) {
97 /* We only need to load once. */
98 lc->ctftab = ef->ctftab;
99 lc->ctfcnt = ef->ctfcnt;
100 lc->symtab = ef->ddbsymtab;
101 lc->strtab = ef->ddbstrtab;
102 lc->strcnt = ef->ddbstrcnt;
103 lc->nsym = ef->ddbsymcnt;
104 lc->ctfoffp = (uint32_t **) &ef->ctfoff;
105 lc->typoffp = (uint32_t **) &ef->typoff;
106 lc->typlenp = &ef->typlen;
107 return (0);
108 }
109
110 /*
111 * We need to try reading the CTF data. Flag no CTF data present
112 * by default and if we actually succeed in reading it, we'll
113 * update ctfcnt to the number of bytes read.
114 */
115 ef->ctfcnt = -1;
116
117 NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, lf->pathname, td);
118 flags = FREAD;
119 error = vn_open(&nd, &flags, 0, NULL);
120 if (error)
121 return (error);
122 NDFREE(&nd, NDF_ONLY_PNBUF);
123
124 /* Allocate memory for the FLF header. */
125 hdr = malloc(sizeof(*hdr), M_LINKER, M_WAITOK);
126
127 /* Read the ELF header. */
128 if ((error = vn_rdwr(UIO_READ, nd.ni_vp, hdr, sizeof(*hdr),
129 0, UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED, NULL,
130 td)) != 0)
131 goto out;
132
133 /* Sanity check. */
134 if (!IS_ELF(*hdr)) {
135 error = ENOEXEC;
136 goto out;
137 }
138
139 nbytes = hdr->e_shnum * hdr->e_shentsize;
140 if (nbytes == 0 || hdr->e_shoff == 0 ||
141 hdr->e_shentsize != sizeof(Elf_Shdr)) {
142 error = ENOEXEC;
143 goto out;
144 }
145
146 /* Allocate memory for all the section headers */
147 shdr = malloc(nbytes, M_LINKER, M_WAITOK);
148
149 /* Read all the section headers */
150 if ((error = vn_rdwr(UIO_READ, nd.ni_vp, (caddr_t)shdr, nbytes,
151 hdr->e_shoff, UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
152 NULL, td)) != 0)
153 goto out;
154
155 /*
156 * We need to search for the CTF section by name, so if the
157 * section names aren't present, then we can't locate the
158 * .SUNW_ctf section containing the CTF data.
159 */
160 if (hdr->e_shstrndx == 0 || shdr[hdr->e_shstrndx].sh_type != SHT_STRTAB) {
161 printf("%s(%d): module %s e_shstrndx is %d, sh_type is %d\n",
162 __func__, __LINE__, lf->pathname, hdr->e_shstrndx,
163 shdr[hdr->e_shstrndx].sh_type);
164 error = EFTYPE;
165 goto out;
166 }
167
168 /* Allocate memory to buffer the section header strings. */
169 shstrtab = malloc(shdr[hdr->e_shstrndx].sh_size, M_LINKER, M_WAITOK);
170
171 /* Read the section header strings. */
172 if ((error = vn_rdwr(UIO_READ, nd.ni_vp, shstrtab,
173 shdr[hdr->e_shstrndx].sh_size, shdr[hdr->e_shstrndx].sh_offset,
174 UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED, NULL, td)) != 0)
175 goto out;
176
177 /* Search for the section containing the CTF data. */
178 for (i = 0; i < hdr->e_shnum; i++)
179 if (strcmp(".SUNW_ctf", shstrtab + shdr[i].sh_name) == 0)
180 break;
181
182 /* Check if the CTF section wasn't found. */
183 if (i >= hdr->e_shnum) {
184 printf("%s(%d): module %s has no .SUNW_ctf section\n",
185 __func__, __LINE__, lf->pathname);
186 error = EFTYPE;
187 goto out;
188 }
189
190 /* Read the CTF header. */
191 if ((error = vn_rdwr(UIO_READ, nd.ni_vp, ctf_hdr, sizeof(ctf_hdr),
192 shdr[i].sh_offset, UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred,
193 NOCRED, NULL, td)) != 0)
194 goto out;
195
196 /* Check the CTF magic number. (XXX check for big endian!) */
197 if (ctf_hdr[0] != 0xf1 || ctf_hdr[1] != 0xcf) {
198 printf("%s(%d): module %s has invalid format\n",
199 __func__, __LINE__, lf->pathname);
200 error = EFTYPE;
201 goto out;
202 }
203
204 /* Check if version 2. */
205 if (ctf_hdr[2] != 2) {
206 printf("%s(%d): module %s CTF format version is %d "
207 "(2 expected)\n",
208 __func__, __LINE__, lf->pathname, ctf_hdr[2]);
209 error = EFTYPE;
210 goto out;
211 }
212
213 /* Check if the data is compressed. */
214 if ((ctf_hdr[3] & 0x1) != 0) {
215 uint32_t *u32 = (uint32_t *) ctf_hdr;
216
217 /*
218 * The last two fields in the CTF header are the offset
219 * from the end of the header to the start of the string
220 * data and the length of that string data. se this
221 * information to determine the decompressed CTF data
222 * buffer required.
223 */
224 sz = u32[CTF_HDR_STRTAB_U32] + u32[CTF_HDR_STRLEN_U32] +
225 sizeof(ctf_hdr);
226
227 /*
228 * Allocate memory for the compressed CTF data, including
229 * the header (which isn't compressed).
230 */
231 raw = malloc(shdr[i].sh_size, M_LINKER, M_WAITOK);
232 } else {
233 /*
234 * The CTF data is not compressed, so the ELF section
235 * size is the same as the buffer size required.
236 */
237 sz = shdr[i].sh_size;
238 }
239
240 /*
241 * Allocate memory to buffer the CTF data in its decompressed
242 * form.
243 */
244 ctftab = malloc(sz, M_LINKER, M_WAITOK);
245
246 /*
247 * Read the CTF data into the raw buffer if compressed, or
248 * directly into the CTF buffer otherwise.
249 */
250 if ((error = vn_rdwr(UIO_READ, nd.ni_vp, raw == NULL ? ctftab : raw,
251 shdr[i].sh_size, shdr[i].sh_offset, UIO_SYSSPACE, IO_NODELOCKED,
252 td->td_ucred, NOCRED, NULL, td)) != 0)
253 goto out;
254
255 /* Check if decompression is required. */
256 if (raw != NULL) {
257 z_stream zs;
258 int ret;
259
260 /*
261 * The header isn't compressed, so copy that into the
262 * CTF buffer first.
263 */
264 bcopy(ctf_hdr, ctftab, sizeof(ctf_hdr));
265
266 /* Initialise the zlib structure. */
267 bzero(&zs, sizeof(zs));
268 zs.zalloc = z_alloc;
269 zs.zfree = z_free;
270
271 if (inflateInit(&zs) != Z_OK) {
272 error = EIO;
273 goto out;
274 }
275
276 zs.avail_in = shdr[i].sh_size - sizeof(ctf_hdr);
277 zs.next_in = ((uint8_t *) raw) + sizeof(ctf_hdr);
278 zs.avail_out = sz - sizeof(ctf_hdr);
279 zs.next_out = ((uint8_t *) ctftab) + sizeof(ctf_hdr);
280 ret = inflate(&zs, Z_FINISH);
281 inflateEnd(&zs);
282 if (ret != Z_STREAM_END) {
283 printf("%s(%d): zlib inflate returned %d\n", __func__, __LINE__, ret);
284 error = EIO;
285 goto out;
286 }
287 }
288
289 /* Got the CTF data! */
290 ef->ctftab = ctftab;
291 ef->ctfcnt = shdr[i].sh_size;
292
293 /* We'll retain the memory allocated for the CTF data. */
294 ctftab = NULL;
295
296 /* Let the caller use the CTF data read. */
297 lc->ctftab = ef->ctftab;
298 lc->ctfcnt = ef->ctfcnt;
299 lc->symtab = ef->ddbsymtab;
300 lc->strtab = ef->ddbstrtab;
301 lc->strcnt = ef->ddbstrcnt;
302 lc->nsym = ef->ddbsymcnt;
303 lc->ctfoffp = (uint32_t **) &ef->ctfoff;
304 lc->typoffp = (uint32_t **) &ef->typoff;
305 lc->typlenp = &ef->typlen;
306
307 out:
308 VOP_UNLOCK(nd.ni_vp, 0);
309 vn_close(nd.ni_vp, FREAD, td->td_ucred, td);
310
311 if (hdr != NULL)
312 free(hdr, M_LINKER);
313 if (shdr != NULL)
314 free(shdr, M_LINKER);
315 if (shstrtab != NULL)
316 free(shstrtab, M_LINKER);
317 if (ctftab != NULL)
318 free(ctftab, M_LINKER);
319 if (raw != NULL)
320 free(raw, M_LINKER);
321 #else
322 error = EOPNOTSUPP;
323 #endif
324
325 return (error);
326 }
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