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: src/sys/kern/kern_ctf.c,v 1.1 2008/05/23 03:04:27 jb Exp $
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 int resid;
72 int vfslocked;
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 (0);
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 | MPSAFE, UIO_SYSSPACE, lf->pathname, td);
118 flags = FREAD;
119 error = vn_open(&nd, &flags, 0, NULL);
120 if (error)
121 return (error);
122 vfslocked = NDHASGIANT(&nd);
123 NDFREE(&nd, NDF_ONLY_PNBUF);
124
125 /* Allocate memory for the FLF header. */
126 if ((hdr = malloc(sizeof(*hdr), M_LINKER, M_WAITOK)) == NULL) {
127 error = ENOMEM;
128 goto out;
129 }
130
131 /* Read the ELF header. */
132 if ((error = vn_rdwr(UIO_READ, nd.ni_vp, hdr, sizeof(*hdr),
133 0, UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED, &resid,
134 td)) != 0)
135 goto out;
136
137 /* Sanity check. */
138 if (!IS_ELF(*hdr)) {
139 error = ENOEXEC;
140 goto out;
141 }
142
143 nbytes = hdr->e_shnum * hdr->e_shentsize;
144 if (nbytes == 0 || hdr->e_shoff == 0 ||
145 hdr->e_shentsize != sizeof(Elf_Shdr)) {
146 error = ENOEXEC;
147 goto out;
148 }
149
150 /* Allocate memory for all the section headers */
151 if ((shdr = malloc(nbytes, M_LINKER, M_WAITOK)) == NULL) {
152 error = ENOMEM;
153 goto out;
154 }
155
156 /* Read all the section headers */
157 if ((error = vn_rdwr(UIO_READ, nd.ni_vp, (caddr_t)shdr, nbytes,
158 hdr->e_shoff, UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
159 &resid, td)) != 0)
160 goto out;
161
162 /*
163 * We need to search for the CTF section by name, so if the
164 * section names aren't present, then we can't locate the
165 * .SUNW_ctf section containing the CTF data.
166 */
167 if (hdr->e_shstrndx == 0 || shdr[hdr->e_shstrndx].sh_type != SHT_STRTAB)
168 goto out;
169
170 /* Allocate memory to buffer the section header strings. */
171 if ((shstrtab = malloc(shdr[hdr->e_shstrndx].sh_size, M_LINKER,
172 M_WAITOK)) == NULL) {
173 error = ENOMEM;
174 goto out;
175 }
176
177 /* Read the section header strings. */
178 if ((error = vn_rdwr(UIO_READ, nd.ni_vp, shstrtab,
179 shdr[hdr->e_shstrndx].sh_size, shdr[hdr->e_shstrndx].sh_offset,
180 UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED, &resid,
181 td)) != 0)
182 goto out;
183
184 /* Search for the section containing the CTF data. */
185 for (i = 0; i < hdr->e_shnum; i++)
186 if (strcmp(".SUNW_ctf", shstrtab + shdr[i].sh_name) == 0)
187 break;
188
189 /* Check if the CTF section wasn't found. */
190 if (i >= hdr->e_shnum)
191 goto out;
192
193 /* Read the CTF header. */
194 if ((error = vn_rdwr(UIO_READ, nd.ni_vp, ctf_hdr, sizeof(ctf_hdr),
195 shdr[i].sh_offset, UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred,
196 NOCRED, &resid, td)) != 0)
197 goto out;
198
199 /* Check the CTF magic number. (XXX check for big endian!) */
200 if (ctf_hdr[0] != 0xf1 || ctf_hdr[1] != 0xcf)
201 goto out;
202
203 /* Check if version 2. */
204 if (ctf_hdr[2] != 2)
205 goto out;
206
207 /* Check if the data is compressed. */
208 if ((ctf_hdr[3] & 0x1) != 0) {
209 uint32_t *u32 = (uint32_t *) ctf_hdr;
210
211 /*
212 * The last two fields in the CTF header are the offset
213 * from the end of the header to the start of the string
214 * data and the length of that string data. se this
215 * information to determine the decompressed CTF data
216 * buffer required.
217 */
218 sz = u32[CTF_HDR_STRTAB_U32] + u32[CTF_HDR_STRLEN_U32] +
219 sizeof(ctf_hdr);
220
221 /*
222 * Allocate memory for the compressed CTF data, including
223 * the header (which isn't compressed).
224 */
225 if ((raw = malloc(shdr[i].sh_size, M_LINKER, M_WAITOK)) == NULL) {
226 error = ENOMEM;
227 goto out;
228 }
229 } else {
230 /*
231 * The CTF data is not compressed, so the ELF section
232 * size is the same as the buffer size required.
233 */
234 sz = shdr[i].sh_size;
235 }
236
237 /*
238 * Allocate memory to buffer the CTF data in it's decompressed
239 * form.
240 */
241 if ((ctftab = malloc(sz, M_LINKER, M_WAITOK)) == NULL) {
242 error = ENOMEM;
243 goto out;
244 }
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, &resid, 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 if ((ret = inflate(&zs, Z_FINISH)) != 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 VFS_UNLOCK_GIANT(vfslocked);
309
310 if (hdr != NULL)
311 free(hdr, M_LINKER);
312 if (shdr != NULL)
313 free(shdr, M_LINKER);
314 if (shstrtab != NULL)
315 free(shstrtab, M_LINKER);
316 if (ctftab != NULL)
317 free(ctftab, M_LINKER);
318 if (raw != NULL)
319 free(raw, M_LINKER);
320 #else
321 error = EOPNOTSUPP;
322 #endif
323
324 return (error);
325 }
326
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