Thomas Gleixner | a7d7a39 | 2019-06-03 07:44:48 +0200 | [diff] [blame] | 1 | // SPDX-License-Identifier: GPL-2.0-only |
Daniel Borkmann | e306e2c | 2013-03-20 12:11:47 +0000 | [diff] [blame] | 2 | /* |
| 3 | * Minimal BPF JIT image disassembler |
| 4 | * |
| 5 | * Disassembles BPF JIT compiler emitted opcodes back to asm insn's for |
| 6 | * debugging or verification purposes. |
| 7 | * |
| 8 | * To get the disassembly of the JIT code, do the following: |
| 9 | * |
| 10 | * 1) `echo 2 > /proc/sys/net/core/bpf_jit_enable` |
| 11 | * 2) Load a BPF filter (e.g. `tcpdump -p -n -s 0 -i eth1 host 192.168.20.0/24`) |
| 12 | * 3) Run e.g. `bpf_jit_disasm -o` to read out the last JIT code |
| 13 | * |
| 14 | * Copyright 2013 Daniel Borkmann <borkmann@redhat.com> |
Daniel Borkmann | e306e2c | 2013-03-20 12:11:47 +0000 | [diff] [blame] | 15 | */ |
| 16 | |
| 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> |
Daniel Borkmann | a6ed383 | 2015-07-30 16:04:22 +0200 | [diff] [blame] | 25 | #include <regex.h> |
| 26 | #include <fcntl.h> |
Daniel Borkmann | e306e2c | 2013-03-20 12:11:47 +0000 | [diff] [blame] | 27 | #include <sys/klog.h> |
| 28 | #include <sys/types.h> |
Daniel Borkmann | a6ed383 | 2015-07-30 16:04:22 +0200 | [diff] [blame] | 29 | #include <sys/stat.h> |
Prashant Bhole | cdc89c9 | 2017-11-02 17:09:45 +0900 | [diff] [blame] | 30 | #include <limits.h> |
Andres Freund | 96ed066 | 2022-07-31 18:38:31 -0700 | [diff] [blame] | 31 | #include <tools/dis-asm-compat.h> |
Daniel Borkmann | a6ed383 | 2015-07-30 16:04:22 +0200 | [diff] [blame] | 32 | |
| 33 | #define CMD_ACTION_SIZE_BUFFER 10 |
| 34 | #define CMD_ACTION_READ_ALL 3 |
Daniel Borkmann | e306e2c | 2013-03-20 12:11:47 +0000 | [diff] [blame] | 35 | |
| 36 | static void get_exec_path(char *tpath, size_t size) |
| 37 | { |
| 38 | char *path; |
| 39 | ssize_t len; |
| 40 | |
| 41 | snprintf(tpath, size, "/proc/%d/exe", (int) getpid()); |
| 42 | tpath[size - 1] = 0; |
| 43 | |
| 44 | path = strdup(tpath); |
| 45 | assert(path); |
| 46 | |
| 47 | len = readlink(path, tpath, size); |
| 48 | tpath[len] = 0; |
| 49 | |
| 50 | free(path); |
| 51 | } |
| 52 | |
Alexei Starovoitov | ed4afd4 | 2014-05-15 15:56:38 -0700 | [diff] [blame] | 53 | static void get_asm_insns(uint8_t *image, size_t len, int opcodes) |
Daniel Borkmann | e306e2c | 2013-03-20 12:11:47 +0000 | [diff] [blame] | 54 | { |
| 55 | int count, i, pc = 0; |
Prashant Bhole | cdc89c9 | 2017-11-02 17:09:45 +0900 | [diff] [blame] | 56 | char tpath[PATH_MAX]; |
Daniel Borkmann | e306e2c | 2013-03-20 12:11:47 +0000 | [diff] [blame] | 57 | struct disassemble_info info; |
| 58 | disassembler_ftype disassemble; |
| 59 | bfd *bfdf; |
| 60 | |
| 61 | memset(tpath, 0, sizeof(tpath)); |
| 62 | get_exec_path(tpath, sizeof(tpath)); |
| 63 | |
| 64 | bfdf = bfd_openr(tpath, NULL); |
| 65 | assert(bfdf); |
| 66 | assert(bfd_check_format(bfdf, bfd_object)); |
| 67 | |
Andres Freund | 96ed066 | 2022-07-31 18:38:31 -0700 | [diff] [blame] | 68 | init_disassemble_info_compat(&info, stdout, |
| 69 | (fprintf_ftype) fprintf, |
| 70 | fprintf_styled); |
Daniel Borkmann | e306e2c | 2013-03-20 12:11:47 +0000 | [diff] [blame] | 71 | info.arch = bfd_get_arch(bfdf); |
| 72 | info.mach = bfd_get_mach(bfdf); |
| 73 | info.buffer = image; |
| 74 | info.buffer_length = len; |
| 75 | |
| 76 | disassemble_init_for_target(&info); |
| 77 | |
Roman Gushchin | fb98266 | 2017-12-27 19:16:29 +0000 | [diff] [blame] | 78 | #ifdef DISASM_FOUR_ARGS_SIGNATURE |
| 79 | disassemble = disassembler(info.arch, |
| 80 | bfd_big_endian(bfdf), |
| 81 | info.mach, |
| 82 | bfdf); |
| 83 | #else |
Daniel Borkmann | e306e2c | 2013-03-20 12:11:47 +0000 | [diff] [blame] | 84 | disassemble = disassembler(bfdf); |
Roman Gushchin | fb98266 | 2017-12-27 19:16:29 +0000 | [diff] [blame] | 85 | #endif |
Daniel Borkmann | e306e2c | 2013-03-20 12:11:47 +0000 | [diff] [blame] | 86 | assert(disassemble); |
| 87 | |
| 88 | do { |
| 89 | printf("%4x:\t", pc); |
| 90 | |
| 91 | count = disassemble(pc, &info); |
| 92 | |
| 93 | if (opcodes) { |
| 94 | printf("\n\t"); |
| 95 | for (i = 0; i < count; ++i) |
| 96 | printf("%02x ", (uint8_t) image[pc + i]); |
| 97 | } |
| 98 | printf("\n"); |
| 99 | |
| 100 | pc += count; |
| 101 | } while(count > 0 && pc < len); |
| 102 | |
| 103 | bfd_close(bfdf); |
| 104 | } |
| 105 | |
Daniel Borkmann | a6ed383 | 2015-07-30 16:04:22 +0200 | [diff] [blame] | 106 | static char *get_klog_buff(unsigned int *klen) |
Daniel Borkmann | e306e2c | 2013-03-20 12:11:47 +0000 | [diff] [blame] | 107 | { |
Daniel Borkmann | a6ed383 | 2015-07-30 16:04:22 +0200 | [diff] [blame] | 108 | int ret, len; |
| 109 | char *buff; |
Daniel Borkmann | e306e2c | 2013-03-20 12:11:47 +0000 | [diff] [blame] | 110 | |
Daniel Borkmann | a6ed383 | 2015-07-30 16:04:22 +0200 | [diff] [blame] | 111 | len = klogctl(CMD_ACTION_SIZE_BUFFER, NULL, 0); |
Colin Ian King | 25a5434 | 2016-05-05 23:39:33 +0100 | [diff] [blame] | 112 | if (len < 0) |
| 113 | return NULL; |
| 114 | |
Daniel Borkmann | a6ed383 | 2015-07-30 16:04:22 +0200 | [diff] [blame] | 115 | buff = malloc(len); |
| 116 | if (!buff) |
| 117 | return NULL; |
| 118 | |
| 119 | ret = klogctl(CMD_ACTION_READ_ALL, buff, len); |
| 120 | if (ret < 0) { |
| 121 | free(buff); |
| 122 | return NULL; |
| 123 | } |
| 124 | |
Daniel Borkmann | e306e2c | 2013-03-20 12:11:47 +0000 | [diff] [blame] | 125 | *klen = ret; |
Daniel Borkmann | e306e2c | 2013-03-20 12:11:47 +0000 | [diff] [blame] | 126 | return buff; |
| 127 | } |
| 128 | |
Daniel Borkmann | a6ed383 | 2015-07-30 16:04:22 +0200 | [diff] [blame] | 129 | static char *get_flog_buff(const char *file, unsigned int *klen) |
| 130 | { |
| 131 | int fd, ret, len; |
| 132 | struct stat fi; |
| 133 | char *buff; |
| 134 | |
| 135 | fd = open(file, O_RDONLY); |
| 136 | if (fd < 0) |
| 137 | return NULL; |
| 138 | |
| 139 | ret = fstat(fd, &fi); |
| 140 | if (ret < 0 || !S_ISREG(fi.st_mode)) |
| 141 | goto out; |
| 142 | |
| 143 | len = fi.st_size + 1; |
| 144 | buff = malloc(len); |
| 145 | if (!buff) |
| 146 | goto out; |
| 147 | |
| 148 | memset(buff, 0, len); |
| 149 | ret = read(fd, buff, len - 1); |
| 150 | if (ret <= 0) |
| 151 | goto out_free; |
| 152 | |
| 153 | close(fd); |
| 154 | *klen = ret; |
| 155 | return buff; |
| 156 | out_free: |
| 157 | free(buff); |
| 158 | out: |
| 159 | close(fd); |
| 160 | return NULL; |
| 161 | } |
| 162 | |
| 163 | static char *get_log_buff(const char *file, unsigned int *klen) |
| 164 | { |
| 165 | return file ? get_flog_buff(file, klen) : get_klog_buff(klen); |
| 166 | } |
| 167 | |
| 168 | static void put_log_buff(char *buff) |
Daniel Borkmann | e306e2c | 2013-03-20 12:11:47 +0000 | [diff] [blame] | 169 | { |
| 170 | free(buff); |
| 171 | } |
| 172 | |
David Daney | e274da1 | 2017-06-13 16:49:35 -0700 | [diff] [blame] | 173 | static uint8_t *get_last_jit_image(char *haystack, size_t hlen, |
| 174 | unsigned int *ilen) |
Daniel Borkmann | e306e2c | 2013-03-20 12:11:47 +0000 | [diff] [blame] | 175 | { |
| 176 | char *ptr, *pptr, *tmp; |
| 177 | off_t off = 0; |
Dan Carpenter | b223e3b | 2018-01-18 12:35:21 +0300 | [diff] [blame] | 178 | unsigned int proglen; |
| 179 | int ret, flen, pass, ulen = 0; |
Daniel Borkmann | e306e2c | 2013-03-20 12:11:47 +0000 | [diff] [blame] | 180 | regmatch_t pmatch[1]; |
Alexei Starovoitov | ed4afd4 | 2014-05-15 15:56:38 -0700 | [diff] [blame] | 181 | unsigned long base; |
Daniel Borkmann | e306e2c | 2013-03-20 12:11:47 +0000 | [diff] [blame] | 182 | regex_t regex; |
David Daney | e274da1 | 2017-06-13 16:49:35 -0700 | [diff] [blame] | 183 | uint8_t *image; |
Daniel Borkmann | e306e2c | 2013-03-20 12:11:47 +0000 | [diff] [blame] | 184 | |
| 185 | if (hlen == 0) |
David Daney | e274da1 | 2017-06-13 16:49:35 -0700 | [diff] [blame] | 186 | return NULL; |
Daniel Borkmann | e306e2c | 2013-03-20 12:11:47 +0000 | [diff] [blame] | 187 | |
| 188 | ret = regcomp(®ex, "flen=[[:alnum:]]+ proglen=[[:digit:]]+ " |
| 189 | "pass=[[:digit:]]+ image=[[:xdigit:]]+", REG_EXTENDED); |
| 190 | assert(ret == 0); |
| 191 | |
| 192 | ptr = haystack; |
Daniel Borkmann | 082739a | 2015-05-25 14:08:03 +0200 | [diff] [blame] | 193 | memset(pmatch, 0, sizeof(pmatch)); |
| 194 | |
Daniel Borkmann | e306e2c | 2013-03-20 12:11:47 +0000 | [diff] [blame] | 195 | while (1) { |
| 196 | ret = regexec(®ex, ptr, 1, pmatch, 0); |
| 197 | if (ret == 0) { |
| 198 | ptr += pmatch[0].rm_eo; |
| 199 | off += pmatch[0].rm_eo; |
| 200 | assert(off < hlen); |
| 201 | } else |
| 202 | break; |
| 203 | } |
| 204 | |
| 205 | ptr = haystack + off - (pmatch[0].rm_eo - pmatch[0].rm_so); |
Dan Carpenter | b223e3b | 2018-01-18 12:35:21 +0300 | [diff] [blame] | 206 | ret = sscanf(ptr, "flen=%d proglen=%u pass=%d image=%lx", |
Alexei Starovoitov | ed4afd4 | 2014-05-15 15:56:38 -0700 | [diff] [blame] | 207 | &flen, &proglen, &pass, &base); |
Daniel Borkmann | a6ed383 | 2015-07-30 16:04:22 +0200 | [diff] [blame] | 208 | if (ret != 4) { |
| 209 | regfree(®ex); |
David Daney | e274da1 | 2017-06-13 16:49:35 -0700 | [diff] [blame] | 210 | return NULL; |
| 211 | } |
| 212 | if (proglen > 1000000) { |
| 213 | printf("proglen of %d too big, stopping\n", proglen); |
| 214 | return NULL; |
Daniel Borkmann | a6ed383 | 2015-07-30 16:04:22 +0200 | [diff] [blame] | 215 | } |
Daniel Borkmann | e306e2c | 2013-03-20 12:11:47 +0000 | [diff] [blame] | 216 | |
David Daney | e274da1 | 2017-06-13 16:49:35 -0700 | [diff] [blame] | 217 | image = malloc(proglen); |
| 218 | if (!image) { |
| 219 | printf("Out of memory\n"); |
| 220 | return NULL; |
| 221 | } |
| 222 | memset(image, 0, proglen); |
| 223 | |
Daniel Borkmann | e306e2c | 2013-03-20 12:11:47 +0000 | [diff] [blame] | 224 | tmp = ptr = haystack + off; |
David Daney | e274da1 | 2017-06-13 16:49:35 -0700 | [diff] [blame] | 225 | while ((ptr = strtok(tmp, "\n")) != NULL && ulen < proglen) { |
Daniel Borkmann | e306e2c | 2013-03-20 12:11:47 +0000 | [diff] [blame] | 226 | tmp = NULL; |
| 227 | if (!strstr(ptr, "JIT code")) |
| 228 | continue; |
| 229 | pptr = ptr; |
| 230 | while ((ptr = strstr(pptr, ":"))) |
| 231 | pptr = ptr + 1; |
| 232 | ptr = pptr; |
| 233 | do { |
| 234 | image[ulen++] = (uint8_t) strtoul(pptr, &pptr, 16); |
David Daney | e274da1 | 2017-06-13 16:49:35 -0700 | [diff] [blame] | 235 | if (ptr == pptr) { |
Daniel Borkmann | e306e2c | 2013-03-20 12:11:47 +0000 | [diff] [blame] | 236 | ulen--; |
| 237 | break; |
| 238 | } |
David Daney | e274da1 | 2017-06-13 16:49:35 -0700 | [diff] [blame] | 239 | if (ulen >= proglen) |
| 240 | break; |
Daniel Borkmann | e306e2c | 2013-03-20 12:11:47 +0000 | [diff] [blame] | 241 | ptr = pptr; |
| 242 | } while (1); |
| 243 | } |
| 244 | |
| 245 | assert(ulen == proglen); |
Dan Carpenter | b223e3b | 2018-01-18 12:35:21 +0300 | [diff] [blame] | 246 | printf("%u bytes emitted from JIT compiler (pass:%d, flen:%d)\n", |
Daniel Borkmann | e306e2c | 2013-03-20 12:11:47 +0000 | [diff] [blame] | 247 | proglen, pass, flen); |
Alexei Starovoitov | ed4afd4 | 2014-05-15 15:56:38 -0700 | [diff] [blame] | 248 | printf("%lx + <x>:\n", base); |
Daniel Borkmann | e306e2c | 2013-03-20 12:11:47 +0000 | [diff] [blame] | 249 | |
| 250 | regfree(®ex); |
David Daney | e274da1 | 2017-06-13 16:49:35 -0700 | [diff] [blame] | 251 | *ilen = ulen; |
| 252 | return image; |
Daniel Borkmann | e306e2c | 2013-03-20 12:11:47 +0000 | [diff] [blame] | 253 | } |
| 254 | |
Daniel Borkmann | a6ed383 | 2015-07-30 16:04:22 +0200 | [diff] [blame] | 255 | static void usage(void) |
| 256 | { |
| 257 | printf("Usage: bpf_jit_disasm [...]\n"); |
| 258 | printf(" -o Also display related opcodes (default: off).\n"); |
David Daney | b6518e6 | 2017-04-11 14:30:52 -0700 | [diff] [blame] | 259 | printf(" -O <file> Write binary image of code to file, don't disassemble to stdout.\n"); |
Daniel Borkmann | a6ed383 | 2015-07-30 16:04:22 +0200 | [diff] [blame] | 260 | printf(" -f <file> Read last image dump from file or stdin (default: klog).\n"); |
| 261 | printf(" -h Display this help.\n"); |
| 262 | } |
| 263 | |
Daniel Borkmann | e306e2c | 2013-03-20 12:11:47 +0000 | [diff] [blame] | 264 | int main(int argc, char **argv) |
| 265 | { |
Daniel Borkmann | a6ed383 | 2015-07-30 16:04:22 +0200 | [diff] [blame] | 266 | unsigned int len, klen, opt, opcodes = 0; |
Daniel Borkmann | a6ed383 | 2015-07-30 16:04:22 +0200 | [diff] [blame] | 267 | char *kbuff, *file = NULL; |
David Daney | b6518e6 | 2017-04-11 14:30:52 -0700 | [diff] [blame] | 268 | char *ofile = NULL; |
| 269 | int ofd; |
| 270 | ssize_t nr; |
| 271 | uint8_t *pos; |
David Daney | e274da1 | 2017-06-13 16:49:35 -0700 | [diff] [blame] | 272 | uint8_t *image = NULL; |
Daniel Borkmann | e306e2c | 2013-03-20 12:11:47 +0000 | [diff] [blame] | 273 | |
David Daney | b6518e6 | 2017-04-11 14:30:52 -0700 | [diff] [blame] | 274 | while ((opt = getopt(argc, argv, "of:O:")) != -1) { |
Daniel Borkmann | a6ed383 | 2015-07-30 16:04:22 +0200 | [diff] [blame] | 275 | switch (opt) { |
| 276 | case 'o': |
Daniel Borkmann | e306e2c | 2013-03-20 12:11:47 +0000 | [diff] [blame] | 277 | opcodes = 1; |
Daniel Borkmann | a6ed383 | 2015-07-30 16:04:22 +0200 | [diff] [blame] | 278 | break; |
David Daney | b6518e6 | 2017-04-11 14:30:52 -0700 | [diff] [blame] | 279 | case 'O': |
| 280 | ofile = optarg; |
| 281 | break; |
Daniel Borkmann | a6ed383 | 2015-07-30 16:04:22 +0200 | [diff] [blame] | 282 | case 'f': |
| 283 | file = optarg; |
| 284 | break; |
| 285 | default: |
| 286 | usage(); |
| 287 | return -1; |
Daniel Borkmann | e306e2c | 2013-03-20 12:11:47 +0000 | [diff] [blame] | 288 | } |
| 289 | } |
| 290 | |
| 291 | bfd_init(); |
Daniel Borkmann | e306e2c | 2013-03-20 12:11:47 +0000 | [diff] [blame] | 292 | |
Daniel Borkmann | a6ed383 | 2015-07-30 16:04:22 +0200 | [diff] [blame] | 293 | kbuff = get_log_buff(file, &klen); |
| 294 | if (!kbuff) { |
| 295 | fprintf(stderr, "Could not retrieve log buffer!\n"); |
| 296 | return -1; |
| 297 | } |
Daniel Borkmann | e306e2c | 2013-03-20 12:11:47 +0000 | [diff] [blame] | 298 | |
David Daney | e274da1 | 2017-06-13 16:49:35 -0700 | [diff] [blame] | 299 | image = get_last_jit_image(kbuff, klen, &len); |
| 300 | if (!image) { |
Daniel Borkmann | a6ed383 | 2015-07-30 16:04:22 +0200 | [diff] [blame] | 301 | fprintf(stderr, "No JIT image found!\n"); |
David Daney | b6518e6 | 2017-04-11 14:30:52 -0700 | [diff] [blame] | 302 | goto done; |
| 303 | } |
| 304 | if (!ofile) { |
| 305 | get_asm_insns(image, len, opcodes); |
| 306 | goto done; |
| 307 | } |
Daniel Borkmann | e306e2c | 2013-03-20 12:11:47 +0000 | [diff] [blame] | 308 | |
David Daney | b6518e6 | 2017-04-11 14:30:52 -0700 | [diff] [blame] | 309 | ofd = open(ofile, O_WRONLY | O_CREAT | O_TRUNC, DEFFILEMODE); |
| 310 | if (ofd < 0) { |
| 311 | fprintf(stderr, "Could not open file %s for writing: ", ofile); |
| 312 | perror(NULL); |
| 313 | goto done; |
| 314 | } |
| 315 | pos = image; |
| 316 | do { |
| 317 | nr = write(ofd, pos, len); |
| 318 | if (nr < 0) { |
| 319 | fprintf(stderr, "Could not write data to %s: ", ofile); |
| 320 | perror(NULL); |
| 321 | goto done; |
| 322 | } |
| 323 | len -= nr; |
| 324 | pos += nr; |
| 325 | } while (len); |
| 326 | close(ofd); |
| 327 | |
| 328 | done: |
Daniel Borkmann | a6ed383 | 2015-07-30 16:04:22 +0200 | [diff] [blame] | 329 | put_log_buff(kbuff); |
David Daney | e274da1 | 2017-06-13 16:49:35 -0700 | [diff] [blame] | 330 | free(image); |
Daniel Borkmann | e306e2c | 2013-03-20 12:11:47 +0000 | [diff] [blame] | 331 | return 0; |
| 332 | } |