FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_ctf.c
1 /*-
2 * Copyright (c) 2008 John Birrell <jb@freebsd.org>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 *
26 * $FreeBSD: releng/11.2/sys/kern/kern_ctf.c 279089 2015-02-20 20:49:00Z markj $
27 */
28
29 /*
30 * Note this file is included by both link_elf.c and link_elf_obj.c.
31 *
32 * The CTF header structure definition can't be used here because it's
33 * (annoyingly) covered by the CDDL. We will just use a few bytes from
34 * it as an integer array where we 'know' what they mean.
35 */
36 #define CTF_HDR_SIZE 36
37 #define CTF_HDR_STRTAB_U32 7
38 #define CTF_HDR_STRLEN_U32 8
39
40 #ifdef DDB_CTF
41 static void *
42 z_alloc(void *nil, u_int items, u_int size)
43 {
44 void *ptr;
45
46 ptr = malloc(items * size, M_TEMP, M_NOWAIT);
47 return ptr;
48 }
49
50 static void
51 z_free(void *nil, void *ptr)
52 {
53 free(ptr, M_TEMP);
54 }
55
56 #endif
57
58 static int
59 link_elf_ctf_get(linker_file_t lf, linker_ctf_t *lc)
60 {
61 #ifdef DDB_CTF
62 Elf_Ehdr *hdr = NULL;
63 Elf_Shdr *shdr = NULL;
64 caddr_t ctftab = NULL;
65 caddr_t raw = NULL;
66 caddr_t shstrtab = NULL;
67 elf_file_t ef = (elf_file_t) lf;
68 int flags;
69 int i;
70 int nbytes;
71 size_t sz;
72 struct nameidata nd;
73 struct thread *td = curthread;
74 uint8_t ctf_hdr[CTF_HDR_SIZE];
75 #endif
76 int error = 0;
77
78 if (lf == NULL || lc == NULL)
79 return (EINVAL);
80
81 /* Set the defaults for no CTF present. That's not a crime! */
82 bzero(lc, sizeof(*lc));
83
84 #ifdef DDB_CTF
85 /*
86 * First check if we've tried to load CTF data previously and the
87 * CTF ELF section wasn't found. We flag that condition by setting
88 * ctfcnt to -1. See below.
89 */
90 if (ef->ctfcnt < 0)
91 return (EFTYPE);
92
93 /* Now check if we've already loaded the CTF data.. */
94 if (ef->ctfcnt > 0) {
95 /* We only need to load once. */
96 lc->ctftab = ef->ctftab;
97 lc->ctfcnt = ef->ctfcnt;
98 lc->symtab = ef->ddbsymtab;
99 lc->strtab = ef->ddbstrtab;
100 lc->strcnt = ef->ddbstrcnt;
101 lc->nsym = ef->ddbsymcnt;
102 lc->ctfoffp = (uint32_t **) &ef->ctfoff;
103 lc->typoffp = (uint32_t **) &ef->typoff;
104 lc->typlenp = &ef->typlen;
105 return (0);
106 }
107
108 /*
109 * We need to try reading the CTF data. Flag no CTF data present
110 * by default and if we actually succeed in reading it, we'll
111 * update ctfcnt to the number of bytes read.
112 */
113 ef->ctfcnt = -1;
114
115 NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, lf->pathname, td);
116 flags = FREAD;
117 error = vn_open(&nd, &flags, 0, NULL);
118 if (error)
119 return (error);
120 NDFREE(&nd, NDF_ONLY_PNBUF);
121
122 /* Allocate memory for the FLF header. */
123 hdr = malloc(sizeof(*hdr), M_LINKER, M_WAITOK);
124
125 /* Read the ELF header. */
126 if ((error = vn_rdwr(UIO_READ, nd.ni_vp, hdr, sizeof(*hdr),
127 0, UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED, NULL,
128 td)) != 0)
129 goto out;
130
131 /* Sanity check. */
132 if (!IS_ELF(*hdr)) {
133 error = ENOEXEC;
134 goto out;
135 }
136
137 nbytes = hdr->e_shnum * hdr->e_shentsize;
138 if (nbytes == 0 || hdr->e_shoff == 0 ||
139 hdr->e_shentsize != sizeof(Elf_Shdr)) {
140 error = ENOEXEC;
141 goto out;
142 }
143
144 /* Allocate memory for all the section headers */
145 shdr = malloc(nbytes, M_LINKER, M_WAITOK);
146
147 /* Read all the section headers */
148 if ((error = vn_rdwr(UIO_READ, nd.ni_vp, (caddr_t)shdr, nbytes,
149 hdr->e_shoff, UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
150 NULL, td)) != 0)
151 goto out;
152
153 /*
154 * We need to search for the CTF section by name, so if the
155 * section names aren't present, then we can't locate the
156 * .SUNW_ctf section containing the CTF data.
157 */
158 if (hdr->e_shstrndx == 0 || shdr[hdr->e_shstrndx].sh_type != SHT_STRTAB) {
159 printf("%s(%d): module %s e_shstrndx is %d, sh_type is %d\n",
160 __func__, __LINE__, lf->pathname, hdr->e_shstrndx,
161 shdr[hdr->e_shstrndx].sh_type);
162 error = EFTYPE;
163 goto out;
164 }
165
166 /* Allocate memory to buffer the section header strings. */
167 shstrtab = malloc(shdr[hdr->e_shstrndx].sh_size, M_LINKER, M_WAITOK);
168
169 /* Read the section header strings. */
170 if ((error = vn_rdwr(UIO_READ, nd.ni_vp, shstrtab,
171 shdr[hdr->e_shstrndx].sh_size, shdr[hdr->e_shstrndx].sh_offset,
172 UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED, NULL, td)) != 0)
173 goto out;
174
175 /* Search for the section containing the CTF data. */
176 for (i = 0; i < hdr->e_shnum; i++)
177 if (strcmp(".SUNW_ctf", shstrtab + shdr[i].sh_name) == 0)
178 break;
179
180 /* Check if the CTF section wasn't found. */
181 if (i >= hdr->e_shnum) {
182 printf("%s(%d): module %s has no .SUNW_ctf section\n",
183 __func__, __LINE__, lf->pathname);
184 error = EFTYPE;
185 goto out;
186 }
187
188 /* Read the CTF header. */
189 if ((error = vn_rdwr(UIO_READ, nd.ni_vp, ctf_hdr, sizeof(ctf_hdr),
190 shdr[i].sh_offset, UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred,
191 NOCRED, NULL, td)) != 0)
192 goto out;
193
194 /* Check the CTF magic number. (XXX check for big endian!) */
195 if (ctf_hdr[0] != 0xf1 || ctf_hdr[1] != 0xcf) {
196 printf("%s(%d): module %s has invalid format\n",
197 __func__, __LINE__, lf->pathname);
198 error = EFTYPE;
199 goto out;
200 }
201
202 /* Check if version 2. */
203 if (ctf_hdr[2] != 2) {
204 printf("%s(%d): module %s CTF format version is %d "
205 "(2 expected)\n",
206 __func__, __LINE__, lf->pathname, ctf_hdr[2]);
207 error = EFTYPE;
208 goto out;
209 }
210
211 /* Check if the data is compressed. */
212 if ((ctf_hdr[3] & 0x1) != 0) {
213 uint32_t *u32 = (uint32_t *) ctf_hdr;
214
215 /*
216 * The last two fields in the CTF header are the offset
217 * from the end of the header to the start of the string
218 * data and the length of that string data. se this
219 * information to determine the decompressed CTF data
220 * buffer required.
221 */
222 sz = u32[CTF_HDR_STRTAB_U32] + u32[CTF_HDR_STRLEN_U32] +
223 sizeof(ctf_hdr);
224
225 /*
226 * Allocate memory for the compressed CTF data, including
227 * the header (which isn't compressed).
228 */
229 raw = malloc(shdr[i].sh_size, M_LINKER, M_WAITOK);
230 } else {
231 /*
232 * The CTF data is not compressed, so the ELF section
233 * size is the same as the buffer size required.
234 */
235 sz = shdr[i].sh_size;
236 }
237
238 /*
239 * Allocate memory to buffer the CTF data in it's decompressed
240 * form.
241 */
242 ctftab = malloc(sz, M_LINKER, M_WAITOK);
243
244 /*
245 * Read the CTF data into the raw buffer if compressed, or
246 * directly into the CTF buffer otherwise.
247 */
248 if ((error = vn_rdwr(UIO_READ, nd.ni_vp, raw == NULL ? ctftab : raw,
249 shdr[i].sh_size, shdr[i].sh_offset, UIO_SYSSPACE, IO_NODELOCKED,
250 td->td_ucred, NOCRED, NULL, td)) != 0)
251 goto out;
252
253 /* Check if decompression is required. */
254 if (raw != NULL) {
255 z_stream zs;
256 int ret;
257
258 /*
259 * The header isn't compressed, so copy that into the
260 * CTF buffer first.
261 */
262 bcopy(ctf_hdr, ctftab, sizeof(ctf_hdr));
263
264 /* Initialise the zlib structure. */
265 bzero(&zs, sizeof(zs));
266 zs.zalloc = z_alloc;
267 zs.zfree = z_free;
268
269 if (inflateInit(&zs) != Z_OK) {
270 error = EIO;
271 goto out;
272 }
273
274 zs.avail_in = shdr[i].sh_size - sizeof(ctf_hdr);
275 zs.next_in = ((uint8_t *) raw) + sizeof(ctf_hdr);
276 zs.avail_out = sz - sizeof(ctf_hdr);
277 zs.next_out = ((uint8_t *) ctftab) + sizeof(ctf_hdr);
278 ret = inflate(&zs, Z_FINISH);
279 inflateEnd(&zs);
280 if (ret != Z_STREAM_END) {
281 printf("%s(%d): zlib inflate returned %d\n", __func__, __LINE__, ret);
282 error = EIO;
283 goto out;
284 }
285 }
286
287 /* Got the CTF data! */
288 ef->ctftab = ctftab;
289 ef->ctfcnt = shdr[i].sh_size;
290
291 /* We'll retain the memory allocated for the CTF data. */
292 ctftab = NULL;
293
294 /* Let the caller use the CTF data read. */
295 lc->ctftab = ef->ctftab;
296 lc->ctfcnt = ef->ctfcnt;
297 lc->symtab = ef->ddbsymtab;
298 lc->strtab = ef->ddbstrtab;
299 lc->strcnt = ef->ddbstrcnt;
300 lc->nsym = ef->ddbsymcnt;
301 lc->ctfoffp = (uint32_t **) &ef->ctfoff;
302 lc->typoffp = (uint32_t **) &ef->typoff;
303 lc->typlenp = &ef->typlen;
304
305 out:
306 VOP_UNLOCK(nd.ni_vp, 0);
307 vn_close(nd.ni_vp, FREAD, td->td_ucred, td);
308
309 if (hdr != NULL)
310 free(hdr, M_LINKER);
311 if (shdr != NULL)
312 free(shdr, M_LINKER);
313 if (shstrtab != NULL)
314 free(shstrtab, M_LINKER);
315 if (ctftab != NULL)
316 free(ctftab, M_LINKER);
317 if (raw != NULL)
318 free(raw, M_LINKER);
319 #else
320 error = EOPNOTSUPP;
321 #endif
322
323 return (error);
324 }
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