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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 buff = malloc(len);
102 if (!buff)
103 return NULL;
104
105 ret = klogctl(CMD_ACTION_READ_ALL, buff, len);
106 if (ret < 0) {
107 free(buff);
108 return NULL;
109 }
110
111 *klen = ret;
112 return buff;
113}
114
115static char *get_flog_buff(const char *file, unsigned int *klen)
116{
117 int fd, ret, len;
118 struct stat fi;
119 char *buff;
120
121 fd = open(file, O_RDONLY);
122 if (fd < 0)
123 return NULL;
124
125 ret = fstat(fd, &fi);
126 if (ret < 0 || !S_ISREG(fi.st_mode))
127 goto out;
128
129 len = fi.st_size + 1;
130 buff = malloc(len);
131 if (!buff)
132 goto out;
133
134 memset(buff, 0, len);
135 ret = read(fd, buff, len - 1);
136 if (ret <= 0)
137 goto out_free;
138
139 close(fd);
140 *klen = ret;
141 return buff;
142out_free:
143 free(buff);
144out:
145 close(fd);
146 return NULL;
147}
148
149static char *get_log_buff(const char *file, unsigned int *klen)
150{
151 return file ? get_flog_buff(file, klen) : get_klog_buff(klen);
152}
153
154static void put_log_buff(char *buff)
155{
156 free(buff);
157}
158
159static int get_last_jit_image(char *haystack, size_t hlen,
160 uint8_t *image, size_t ilen)
161{
162 char *ptr, *pptr, *tmp;
163 off_t off = 0;
164 int ret, flen, proglen, pass, ulen = 0;
165 regmatch_t pmatch[1];
166 unsigned long base;
167 regex_t regex;
168
169 if (hlen == 0)
170 return 0;
171
172 ret = regcomp(®ex, "flen=[[:alnum:]]+ proglen=[[:digit:]]+ "
173 "pass=[[:digit:]]+ image=[[:xdigit:]]+", REG_EXTENDED);
174 assert(ret == 0);
175
176 ptr = haystack;
177 memset(pmatch, 0, sizeof(pmatch));
178
179 while (1) {
180 ret = regexec(®ex, ptr, 1, pmatch, 0);
181 if (ret == 0) {
182 ptr += pmatch[0].rm_eo;
183 off += pmatch[0].rm_eo;
184 assert(off < hlen);
185 } else
186 break;
187 }
188
189 ptr = haystack + off - (pmatch[0].rm_eo - pmatch[0].rm_so);
190 ret = sscanf(ptr, "flen=%d proglen=%d pass=%d image=%lx",
191 &flen, &proglen, &pass, &base);
192 if (ret != 4) {
193 regfree(®ex);
194 return 0;
195 }
196
197 tmp = ptr = haystack + off;
198 while ((ptr = strtok(tmp, "\n")) != NULL && ulen < ilen) {
199 tmp = NULL;
200 if (!strstr(ptr, "JIT code"))
201 continue;
202 pptr = ptr;
203 while ((ptr = strstr(pptr, ":")))
204 pptr = ptr + 1;
205 ptr = pptr;
206 do {
207 image[ulen++] = (uint8_t) strtoul(pptr, &pptr, 16);
208 if (ptr == pptr || ulen >= ilen) {
209 ulen--;
210 break;
211 }
212 ptr = pptr;
213 } while (1);
214 }
215
216 assert(ulen == proglen);
217 printf("%d bytes emitted from JIT compiler (pass:%d, flen:%d)\n",
218 proglen, pass, flen);
219 printf("%lx + <x>:\n", base);
220
221 regfree(®ex);
222 return ulen;
223}
224
225static void usage(void)
226{
227 printf("Usage: bpf_jit_disasm [...]\n");
228 printf(" -o Also display related opcodes (default: off).\n");
229 printf(" -f <file> Read last image dump from file or stdin (default: klog).\n");
230 printf(" -h Display this help.\n");
231}
232
233int main(int argc, char **argv)
234{
235 unsigned int len, klen, opt, opcodes = 0;
236 static uint8_t image[32768];
237 char *kbuff, *file = NULL;
238
239 while ((opt = getopt(argc, argv, "of:")) != -1) {
240 switch (opt) {
241 case 'o':
242 opcodes = 1;
243 break;
244 case 'f':
245 file = optarg;
246 break;
247 default:
248 usage();
249 return -1;
250 }
251 }
252
253 bfd_init();
254 memset(image, 0, sizeof(image));
255
256 kbuff = get_log_buff(file, &klen);
257 if (!kbuff) {
258 fprintf(stderr, "Could not retrieve log buffer!\n");
259 return -1;
260 }
261
262 len = get_last_jit_image(kbuff, klen, image, sizeof(image));
263 if (len > 0)
264 get_asm_insns(image, len, opcodes);
265 else
266 fprintf(stderr, "No JIT image found!\n");
267
268 put_log_buff(kbuff);
269 return 0;
270}
271
