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17#include <stdint.h>
18#include <stdio.h>
19#include <stdlib.h>
20#include <assert.h>
21#include <unistd.h>
22#include <string.h>
23#include <bfd.h>
24#include <dis-asm.h>
25#include <regex.h>
26#include <fcntl.h>
27#include <sys/klog.h>
28#include <sys/types.h>
29#include <sys/stat.h>
30
31#define CMD_ACTION_SIZE_BUFFER 10
32#define CMD_ACTION_READ_ALL 3
33
34static void get_exec_path(char *tpath, size_t size)
35{
36 char *path;
37 ssize_t len;
38
39 snprintf(tpath, size, "/proc/%d/exe", (int) getpid());
40 tpath[size - 1] = 0;
41
42 path = strdup(tpath);
43 assert(path);
44
45 len = readlink(path, tpath, size);
46 tpath[len] = 0;
47
48 free(path);
49}
50
51static void get_asm_insns(uint8_t *image, size_t len, int opcodes)
52{
53 int count, i, pc = 0;
54 char tpath[256];
55 struct disassemble_info info;
56 disassembler_ftype disassemble;
57 bfd *bfdf;
58
59 memset(tpath, 0, sizeof(tpath));
60 get_exec_path(tpath, sizeof(tpath));
61
62 bfdf = bfd_openr(tpath, NULL);
63 assert(bfdf);
64 assert(bfd_check_format(bfdf, bfd_object));
65
66 init_disassemble_info(&info, stdout, (fprintf_ftype) fprintf);
67 info.arch = bfd_get_arch(bfdf);
68 info.mach = bfd_get_mach(bfdf);
69 info.buffer = image;
70 info.buffer_length = len;
71
72 disassemble_init_for_target(&info);
73
74 disassemble = disassembler(bfdf);
75 assert(disassemble);
76
77 do {
78 printf("%4x:\t", pc);
79
80 count = disassemble(pc, &info);
81
82 if (opcodes) {
83 printf("\n\t");
84 for (i = 0; i < count; ++i)
85 printf("%02x ", (uint8_t) image[pc + i]);
86 }
87 printf("\n");
88
89 pc += count;
90 } while(count > 0 && pc < len);
91
92 bfd_close(bfdf);
93}
94
95static char *get_klog_buff(unsigned int *klen)
96{
97 int ret, len;
98 char *buff;
99
100 len = klogctl(CMD_ACTION_SIZE_BUFFER, NULL, 0);
101 if (len < 0)
102 return NULL;
103
104 buff = malloc(len);
105 if (!buff)
106 return NULL;
107
108 ret = klogctl(CMD_ACTION_READ_ALL, buff, len);
109 if (ret < 0) {
110 free(buff);
111 return NULL;
112 }
113
114 *klen = ret;
115 return buff;
116}
117
118static char *get_flog_buff(const char *file, unsigned int *klen)
119{
120 int fd, ret, len;
121 struct stat fi;
122 char *buff;
123
124 fd = open(file, O_RDONLY);
125 if (fd < 0)
126 return NULL;
127
128 ret = fstat(fd, &fi);
129 if (ret < 0 || !S_ISREG(fi.st_mode))
130 goto out;
131
132 len = fi.st_size + 1;
133 buff = malloc(len);
134 if (!buff)
135 goto out;
136
137 memset(buff, 0, len);
138 ret = read(fd, buff, len - 1);
139 if (ret <= 0)
140 goto out_free;
141
142 close(fd);
143 *klen = ret;
144 return buff;
145out_free:
146 free(buff);
147out:
148 close(fd);
149 return NULL;
150}
151
152static char *get_log_buff(const char *file, unsigned int *klen)
153{
154 return file ? get_flog_buff(file, klen) : get_klog_buff(klen);
155}
156
157static void put_log_buff(char *buff)
158{
159 free(buff);
160}
161
162static uint8_t *get_last_jit_image(char *haystack, size_t hlen,
163 unsigned int *ilen)
164{
165 char *ptr, *pptr, *tmp;
166 off_t off = 0;
167 int ret, flen, proglen, pass, ulen = 0;
168 regmatch_t pmatch[1];
169 unsigned long base;
170 regex_t regex;
171 uint8_t *image;
172
173 if (hlen == 0)
174 return NULL;
175
176 ret = regcomp(®ex, "flen=[[:alnum:]]+ proglen=[[:digit:]]+ "
177 "pass=[[:digit:]]+ image=[[:xdigit:]]+", REG_EXTENDED);
178 assert(ret == 0);
179
180 ptr = haystack;
181 memset(pmatch, 0, sizeof(pmatch));
182
183 while (1) {
184 ret = regexec(®ex, ptr, 1, pmatch, 0);
185 if (ret == 0) {
186 ptr += pmatch[0].rm_eo;
187 off += pmatch[0].rm_eo;
188 assert(off < hlen);
189 } else
190 break;
191 }
192
193 ptr = haystack + off - (pmatch[0].rm_eo - pmatch[0].rm_so);
194 ret = sscanf(ptr, "flen=%d proglen=%d pass=%d image=%lx",
195 &flen, &proglen, &pass, &base);
196 if (ret != 4) {
197 regfree(®ex);
198 return NULL;
199 }
200 if (proglen > 1000000) {
201 printf("proglen of %d too big, stopping\n", proglen);
202 return NULL;
203 }
204
205 image = malloc(proglen);
206 if (!image) {
207 printf("Out of memory\n");
208 return NULL;
209 }
210 memset(image, 0, proglen);
211
212 tmp = ptr = haystack + off;
213 while ((ptr = strtok(tmp, "\n")) != NULL && ulen < proglen) {
214 tmp = NULL;
215 if (!strstr(ptr, "JIT code"))
216 continue;
217 pptr = ptr;
218 while ((ptr = strstr(pptr, ":")))
219 pptr = ptr + 1;
220 ptr = pptr;
221 do {
222 image[ulen++] = (uint8_t) strtoul(pptr, &pptr, 16);
223 if (ptr == pptr) {
224 ulen--;
225 break;
226 }
227 if (ulen >= proglen)
228 break;
229 ptr = pptr;
230 } while (1);
231 }
232
233 assert(ulen == proglen);
234 printf("%d bytes emitted from JIT compiler (pass:%d, flen:%d)\n",
235 proglen, pass, flen);
236 printf("%lx + <x>:\n", base);
237
238 regfree(®ex);
239 *ilen = ulen;
240 return image;
241}
242
243static void usage(void)
244{
245 printf("Usage: bpf_jit_disasm [...]\n");
246 printf(" -o Also display related opcodes (default: off).\n");
247 printf(" -O <file> Write binary image of code to file, don't disassemble to stdout.\n");
248 printf(" -f <file> Read last image dump from file or stdin (default: klog).\n");
249 printf(" -h Display this help.\n");
250}
251
252int main(int argc, char **argv)
253{
254 unsigned int len, klen, opt, opcodes = 0;
255 char *kbuff, *file = NULL;
256 char *ofile = NULL;
257 int ofd;
258 ssize_t nr;
259 uint8_t *pos;
260 uint8_t *image = NULL;
261
262 while ((opt = getopt(argc, argv, "of:O:")) != -1) {
263 switch (opt) {
264 case 'o':
265 opcodes = 1;
266 break;
267 case 'O':
268 ofile = optarg;
269 break;
270 case 'f':
271 file = optarg;
272 break;
273 default:
274 usage();
275 return -1;
276 }
277 }
278
279 bfd_init();
280
281 kbuff = get_log_buff(file, &klen);
282 if (!kbuff) {
283 fprintf(stderr, "Could not retrieve log buffer!\n");
284 return -1;
285 }
286
287 image = get_last_jit_image(kbuff, klen, &len);
288 if (!image) {
289 fprintf(stderr, "No JIT image found!\n");
290 goto done;
291 }
292 if (!ofile) {
293 get_asm_insns(image, len, opcodes);
294 goto done;
295 }
296
297 ofd = open(ofile, O_WRONLY | O_CREAT | O_TRUNC, DEFFILEMODE);
298 if (ofd < 0) {
299 fprintf(stderr, "Could not open file %s for writing: ", ofile);
300 perror(NULL);
301 goto done;
302 }
303 pos = image;
304 do {
305 nr = write(ofd, pos, len);
306 if (nr < 0) {
307 fprintf(stderr, "Could not write data to %s: ", ofile);
308 perror(NULL);
309 goto done;
310 }
311 len -= nr;
312 pos += nr;
313 } while (len);
314 close(ofd);
315
316done:
317 put_log_buff(kbuff);
318 free(image);
319 return 0;
320}
321
