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Linux/samples/bpf/bpf_load.c

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  1 // SPDX-License-Identifier: GPL-2.0
  2 #include <stdio.h>
  3 #include <sys/types.h>
  4 #include <sys/stat.h>
  5 #include <fcntl.h>
  6 #include <libelf.h>
  7 #include <gelf.h>
  8 #include <errno.h>
  9 #include <unistd.h>
 10 #include <string.h>
 11 #include <stdbool.h>
 12 #include <stdlib.h>
 13 #include <linux/bpf.h>
 14 #include <linux/filter.h>
 15 #include <linux/perf_event.h>
 16 #include <linux/netlink.h>
 17 #include <linux/rtnetlink.h>
 18 #include <linux/types.h>
 19 #include <sys/types.h>
 20 #include <sys/socket.h>
 21 #include <sys/syscall.h>
 22 #include <sys/ioctl.h>
 23 #include <sys/mman.h>
 24 #include <poll.h>
 25 #include <ctype.h>
 26 #include <assert.h>
 27 #include "libbpf.h"
 28 #include "bpf_load.h"
 29 #include "perf-sys.h"
 30 
 31 #define DEBUGFS "/sys/kernel/debug/tracing/"
 32 
 33 static char license[128];
 34 static int kern_version;
 35 static bool processed_sec[128];
 36 char bpf_log_buf[BPF_LOG_BUF_SIZE];
 37 int map_fd[MAX_MAPS];
 38 int prog_fd[MAX_PROGS];
 39 int event_fd[MAX_PROGS];
 40 int prog_cnt;
 41 int prog_array_fd = -1;
 42 
 43 struct bpf_map_data map_data[MAX_MAPS];
 44 int map_data_count = 0;
 45 
 46 static int populate_prog_array(const char *event, int prog_fd)
 47 {
 48         int ind = atoi(event), err;
 49 
 50         err = bpf_map_update_elem(prog_array_fd, &ind, &prog_fd, BPF_ANY);
 51         if (err < 0) {
 52                 printf("failed to store prog_fd in prog_array\n");
 53                 return -1;
 54         }
 55         return 0;
 56 }
 57 
 58 static int load_and_attach(const char *event, struct bpf_insn *prog, int size)
 59 {
 60         bool is_socket = strncmp(event, "socket", 6) == 0;
 61         bool is_kprobe = strncmp(event, "kprobe/", 7) == 0;
 62         bool is_kretprobe = strncmp(event, "kretprobe/", 10) == 0;
 63         bool is_tracepoint = strncmp(event, "tracepoint/", 11) == 0;
 64         bool is_raw_tracepoint = strncmp(event, "raw_tracepoint/", 15) == 0;
 65         bool is_xdp = strncmp(event, "xdp", 3) == 0;
 66         bool is_perf_event = strncmp(event, "perf_event", 10) == 0;
 67         bool is_cgroup_skb = strncmp(event, "cgroup/skb", 10) == 0;
 68         bool is_cgroup_sk = strncmp(event, "cgroup/sock", 11) == 0;
 69         bool is_sockops = strncmp(event, "sockops", 7) == 0;
 70         bool is_sk_skb = strncmp(event, "sk_skb", 6) == 0;
 71         bool is_sk_msg = strncmp(event, "sk_msg", 6) == 0;
 72         size_t insns_cnt = size / sizeof(struct bpf_insn);
 73         enum bpf_prog_type prog_type;
 74         char buf[256];
 75         int fd, efd, err, id;
 76         struct perf_event_attr attr = {};
 77 
 78         attr.type = PERF_TYPE_TRACEPOINT;
 79         attr.sample_type = PERF_SAMPLE_RAW;
 80         attr.sample_period = 1;
 81         attr.wakeup_events = 1;
 82 
 83         if (is_socket) {
 84                 prog_type = BPF_PROG_TYPE_SOCKET_FILTER;
 85         } else if (is_kprobe || is_kretprobe) {
 86                 prog_type = BPF_PROG_TYPE_KPROBE;
 87         } else if (is_tracepoint) {
 88                 prog_type = BPF_PROG_TYPE_TRACEPOINT;
 89         } else if (is_raw_tracepoint) {
 90                 prog_type = BPF_PROG_TYPE_RAW_TRACEPOINT;
 91         } else if (is_xdp) {
 92                 prog_type = BPF_PROG_TYPE_XDP;
 93         } else if (is_perf_event) {
 94                 prog_type = BPF_PROG_TYPE_PERF_EVENT;
 95         } else if (is_cgroup_skb) {
 96                 prog_type = BPF_PROG_TYPE_CGROUP_SKB;
 97         } else if (is_cgroup_sk) {
 98                 prog_type = BPF_PROG_TYPE_CGROUP_SOCK;
 99         } else if (is_sockops) {
100                 prog_type = BPF_PROG_TYPE_SOCK_OPS;
101         } else if (is_sk_skb) {
102                 prog_type = BPF_PROG_TYPE_SK_SKB;
103         } else if (is_sk_msg) {
104                 prog_type = BPF_PROG_TYPE_SK_MSG;
105         } else {
106                 printf("Unknown event '%s'\n", event);
107                 return -1;
108         }
109 
110         fd = bpf_load_program(prog_type, prog, insns_cnt, license, kern_version,
111                               bpf_log_buf, BPF_LOG_BUF_SIZE);
112         if (fd < 0) {
113                 printf("bpf_load_program() err=%d\n%s", errno, bpf_log_buf);
114                 return -1;
115         }
116 
117         prog_fd[prog_cnt++] = fd;
118 
119         if (is_xdp || is_perf_event || is_cgroup_skb || is_cgroup_sk)
120                 return 0;
121 
122         if (is_socket || is_sockops || is_sk_skb || is_sk_msg) {
123                 if (is_socket)
124                         event += 6;
125                 else
126                         event += 7;
127                 if (*event != '/')
128                         return 0;
129                 event++;
130                 if (!isdigit(*event)) {
131                         printf("invalid prog number\n");
132                         return -1;
133                 }
134                 return populate_prog_array(event, fd);
135         }
136 
137         if (is_raw_tracepoint) {
138                 efd = bpf_raw_tracepoint_open(event + 15, fd);
139                 if (efd < 0) {
140                         printf("tracepoint %s %s\n", event + 15, strerror(errno));
141                         return -1;
142                 }
143                 event_fd[prog_cnt - 1] = efd;
144                 return 0;
145         }
146 
147         if (is_kprobe || is_kretprobe) {
148                 if (is_kprobe)
149                         event += 7;
150                 else
151                         event += 10;
152 
153                 if (*event == 0) {
154                         printf("event name cannot be empty\n");
155                         return -1;
156                 }
157 
158                 if (isdigit(*event))
159                         return populate_prog_array(event, fd);
160 
161                 snprintf(buf, sizeof(buf),
162                          "echo '%c:%s %s' >> /sys/kernel/debug/tracing/kprobe_events",
163                          is_kprobe ? 'p' : 'r', event, event);
164                 err = system(buf);
165                 if (err < 0) {
166                         printf("failed to create kprobe '%s' error '%s'\n",
167                                event, strerror(errno));
168                         return -1;
169                 }
170 
171                 strcpy(buf, DEBUGFS);
172                 strcat(buf, "events/kprobes/");
173                 strcat(buf, event);
174                 strcat(buf, "/id");
175         } else if (is_tracepoint) {
176                 event += 11;
177 
178                 if (*event == 0) {
179                         printf("event name cannot be empty\n");
180                         return -1;
181                 }
182                 strcpy(buf, DEBUGFS);
183                 strcat(buf, "events/");
184                 strcat(buf, event);
185                 strcat(buf, "/id");
186         }
187 
188         efd = open(buf, O_RDONLY, 0);
189         if (efd < 0) {
190                 printf("failed to open event %s\n", event);
191                 return -1;
192         }
193 
194         err = read(efd, buf, sizeof(buf));
195         if (err < 0 || err >= sizeof(buf)) {
196                 printf("read from '%s' failed '%s'\n", event, strerror(errno));
197                 return -1;
198         }
199 
200         close(efd);
201 
202         buf[err] = 0;
203         id = atoi(buf);
204         attr.config = id;
205 
206         efd = sys_perf_event_open(&attr, -1/*pid*/, 0/*cpu*/, -1/*group_fd*/, 0);
207         if (efd < 0) {
208                 printf("event %d fd %d err %s\n", id, efd, strerror(errno));
209                 return -1;
210         }
211         event_fd[prog_cnt - 1] = efd;
212         err = ioctl(efd, PERF_EVENT_IOC_ENABLE, 0);
213         if (err < 0) {
214                 printf("ioctl PERF_EVENT_IOC_ENABLE failed err %s\n",
215                        strerror(errno));
216                 return -1;
217         }
218         err = ioctl(efd, PERF_EVENT_IOC_SET_BPF, fd);
219         if (err < 0) {
220                 printf("ioctl PERF_EVENT_IOC_SET_BPF failed err %s\n",
221                        strerror(errno));
222                 return -1;
223         }
224 
225         return 0;
226 }
227 
228 static int load_maps(struct bpf_map_data *maps, int nr_maps,
229                      fixup_map_cb fixup_map)
230 {
231         int i, numa_node;
232 
233         for (i = 0; i < nr_maps; i++) {
234                 if (fixup_map) {
235                         fixup_map(&maps[i], i);
236                         /* Allow userspace to assign map FD prior to creation */
237                         if (maps[i].fd != -1) {
238                                 map_fd[i] = maps[i].fd;
239                                 continue;
240                         }
241                 }
242 
243                 numa_node = maps[i].def.map_flags & BPF_F_NUMA_NODE ?
244                         maps[i].def.numa_node : -1;
245 
246                 if (maps[i].def.type == BPF_MAP_TYPE_ARRAY_OF_MAPS ||
247                     maps[i].def.type == BPF_MAP_TYPE_HASH_OF_MAPS) {
248                         int inner_map_fd = map_fd[maps[i].def.inner_map_idx];
249 
250                         map_fd[i] = bpf_create_map_in_map_node(maps[i].def.type,
251                                                         maps[i].name,
252                                                         maps[i].def.key_size,
253                                                         inner_map_fd,
254                                                         maps[i].def.max_entries,
255                                                         maps[i].def.map_flags,
256                                                         numa_node);
257                 } else {
258                         map_fd[i] = bpf_create_map_node(maps[i].def.type,
259                                                         maps[i].name,
260                                                         maps[i].def.key_size,
261                                                         maps[i].def.value_size,
262                                                         maps[i].def.max_entries,
263                                                         maps[i].def.map_flags,
264                                                         numa_node);
265                 }
266                 if (map_fd[i] < 0) {
267                         printf("failed to create a map: %d %s\n",
268                                errno, strerror(errno));
269                         return 1;
270                 }
271                 maps[i].fd = map_fd[i];
272 
273                 if (maps[i].def.type == BPF_MAP_TYPE_PROG_ARRAY)
274                         prog_array_fd = map_fd[i];
275         }
276         return 0;
277 }
278 
279 static int get_sec(Elf *elf, int i, GElf_Ehdr *ehdr, char **shname,
280                    GElf_Shdr *shdr, Elf_Data **data)
281 {
282         Elf_Scn *scn;
283 
284         scn = elf_getscn(elf, i);
285         if (!scn)
286                 return 1;
287 
288         if (gelf_getshdr(scn, shdr) != shdr)
289                 return 2;
290 
291         *shname = elf_strptr(elf, ehdr->e_shstrndx, shdr->sh_name);
292         if (!*shname || !shdr->sh_size)
293                 return 3;
294 
295         *data = elf_getdata(scn, 0);
296         if (!*data || elf_getdata(scn, *data) != NULL)
297                 return 4;
298 
299         return 0;
300 }
301 
302 static int parse_relo_and_apply(Elf_Data *data, Elf_Data *symbols,
303                                 GElf_Shdr *shdr, struct bpf_insn *insn,
304                                 struct bpf_map_data *maps, int nr_maps)
305 {
306         int i, nrels;
307 
308         nrels = shdr->sh_size / shdr->sh_entsize;
309 
310         for (i = 0; i < nrels; i++) {
311                 GElf_Sym sym;
312                 GElf_Rel rel;
313                 unsigned int insn_idx;
314                 bool match = false;
315                 int j, map_idx;
316 
317                 gelf_getrel(data, i, &rel);
318 
319                 insn_idx = rel.r_offset / sizeof(struct bpf_insn);
320 
321                 gelf_getsym(symbols, GELF_R_SYM(rel.r_info), &sym);
322 
323                 if (insn[insn_idx].code != (BPF_LD | BPF_IMM | BPF_DW)) {
324                         printf("invalid relo for insn[%d].code 0x%x\n",
325                                insn_idx, insn[insn_idx].code);
326                         return 1;
327                 }
328                 insn[insn_idx].src_reg = BPF_PSEUDO_MAP_FD;
329 
330                 /* Match FD relocation against recorded map_data[] offset */
331                 for (map_idx = 0; map_idx < nr_maps; map_idx++) {
332                         if (maps[map_idx].elf_offset == sym.st_value) {
333                                 match = true;
334                                 break;
335                         }
336                 }
337                 if (match) {
338                         insn[insn_idx].imm = maps[map_idx].fd;
339                 } else {
340                         printf("invalid relo for insn[%d] no map_data match\n",
341                                insn_idx);
342                         return 1;
343                 }
344         }
345 
346         return 0;
347 }
348 
349 static int cmp_symbols(const void *l, const void *r)
350 {
351         const GElf_Sym *lsym = (const GElf_Sym *)l;
352         const GElf_Sym *rsym = (const GElf_Sym *)r;
353 
354         if (lsym->st_value < rsym->st_value)
355                 return -1;
356         else if (lsym->st_value > rsym->st_value)
357                 return 1;
358         else
359                 return 0;
360 }
361 
362 static int load_elf_maps_section(struct bpf_map_data *maps, int maps_shndx,
363                                  Elf *elf, Elf_Data *symbols, int strtabidx)
364 {
365         int map_sz_elf, map_sz_copy;
366         bool validate_zero = false;
367         Elf_Data *data_maps;
368         int i, nr_maps;
369         GElf_Sym *sym;
370         Elf_Scn *scn;
371         int copy_sz;
372 
373         if (maps_shndx < 0)
374                 return -EINVAL;
375         if (!symbols)
376                 return -EINVAL;
377 
378         /* Get data for maps section via elf index */
379         scn = elf_getscn(elf, maps_shndx);
380         if (scn)
381                 data_maps = elf_getdata(scn, NULL);
382         if (!scn || !data_maps) {
383                 printf("Failed to get Elf_Data from maps section %d\n",
384                        maps_shndx);
385                 return -EINVAL;
386         }
387 
388         /* For each map get corrosponding symbol table entry */
389         sym = calloc(MAX_MAPS+1, sizeof(GElf_Sym));
390         for (i = 0, nr_maps = 0; i < symbols->d_size / sizeof(GElf_Sym); i++) {
391                 assert(nr_maps < MAX_MAPS+1);
392                 if (!gelf_getsym(symbols, i, &sym[nr_maps]))
393                         continue;
394                 if (sym[nr_maps].st_shndx != maps_shndx)
395                         continue;
396                 /* Only increment iif maps section */
397                 nr_maps++;
398         }
399 
400         /* Align to map_fd[] order, via sort on offset in sym.st_value */
401         qsort(sym, nr_maps, sizeof(GElf_Sym), cmp_symbols);
402 
403         /* Keeping compatible with ELF maps section changes
404          * ------------------------------------------------
405          * The program size of struct bpf_map_def is known by loader
406          * code, but struct stored in ELF file can be different.
407          *
408          * Unfortunately sym[i].st_size is zero.  To calculate the
409          * struct size stored in the ELF file, assume all struct have
410          * the same size, and simply divide with number of map
411          * symbols.
412          */
413         map_sz_elf = data_maps->d_size / nr_maps;
414         map_sz_copy = sizeof(struct bpf_map_def);
415         if (map_sz_elf < map_sz_copy) {
416                 /*
417                  * Backward compat, loading older ELF file with
418                  * smaller struct, keeping remaining bytes zero.
419                  */
420                 map_sz_copy = map_sz_elf;
421         } else if (map_sz_elf > map_sz_copy) {
422                 /*
423                  * Forward compat, loading newer ELF file with larger
424                  * struct with unknown features. Assume zero means
425                  * feature not used.  Thus, validate rest of struct
426                  * data is zero.
427                  */
428                 validate_zero = true;
429         }
430 
431         /* Memcpy relevant part of ELF maps data to loader maps */
432         for (i = 0; i < nr_maps; i++) {
433                 unsigned char *addr, *end;
434                 struct bpf_map_def *def;
435                 const char *map_name;
436                 size_t offset;
437 
438                 map_name = elf_strptr(elf, strtabidx, sym[i].st_name);
439                 maps[i].name = strdup(map_name);
440                 if (!maps[i].name) {
441                         printf("strdup(%s): %s(%d)\n", map_name,
442                                strerror(errno), errno);
443                         free(sym);
444                         return -errno;
445                 }
446 
447                 /* Symbol value is offset into ELF maps section data area */
448                 offset = sym[i].st_value;
449                 def = (struct bpf_map_def *)(data_maps->d_buf + offset);
450                 maps[i].elf_offset = offset;
451                 memset(&maps[i].def, 0, sizeof(struct bpf_map_def));
452                 memcpy(&maps[i].def, def, map_sz_copy);
453 
454                 /* Verify no newer features were requested */
455                 if (validate_zero) {
456                         addr = (unsigned char*) def + map_sz_copy;
457                         end  = (unsigned char*) def + map_sz_elf;
458                         for (; addr < end; addr++) {
459                                 if (*addr != 0) {
460                                         free(sym);
461                                         return -EFBIG;
462                                 }
463                         }
464                 }
465         }
466 
467         free(sym);
468         return nr_maps;
469 }
470 
471 static int do_load_bpf_file(const char *path, fixup_map_cb fixup_map)
472 {
473         int fd, i, ret, maps_shndx = -1, strtabidx = -1;
474         Elf *elf;
475         GElf_Ehdr ehdr;
476         GElf_Shdr shdr, shdr_prog;
477         Elf_Data *data, *data_prog, *data_maps = NULL, *symbols = NULL;
478         char *shname, *shname_prog;
479         int nr_maps = 0;
480 
481         /* reset global variables */
482         kern_version = 0;
483         memset(license, 0, sizeof(license));
484         memset(processed_sec, 0, sizeof(processed_sec));
485 
486         if (elf_version(EV_CURRENT) == EV_NONE)
487                 return 1;
488 
489         fd = open(path, O_RDONLY, 0);
490         if (fd < 0)
491                 return 1;
492 
493         elf = elf_begin(fd, ELF_C_READ, NULL);
494 
495         if (!elf)
496                 return 1;
497 
498         if (gelf_getehdr(elf, &ehdr) != &ehdr)
499                 return 1;
500 
501         /* clear all kprobes */
502         i = system("echo \"\" > /sys/kernel/debug/tracing/kprobe_events");
503 
504         /* scan over all elf sections to get license and map info */
505         for (i = 1; i < ehdr.e_shnum; i++) {
506 
507                 if (get_sec(elf, i, &ehdr, &shname, &shdr, &data))
508                         continue;
509 
510                 if (0) /* helpful for llvm debugging */
511                         printf("section %d:%s data %p size %zd link %d flags %d\n",
512                                i, shname, data->d_buf, data->d_size,
513                                shdr.sh_link, (int) shdr.sh_flags);
514 
515                 if (strcmp(shname, "license") == 0) {
516                         processed_sec[i] = true;
517                         memcpy(license, data->d_buf, data->d_size);
518                 } else if (strcmp(shname, "version") == 0) {
519                         processed_sec[i] = true;
520                         if (data->d_size != sizeof(int)) {
521                                 printf("invalid size of version section %zd\n",
522                                        data->d_size);
523                                 return 1;
524                         }
525                         memcpy(&kern_version, data->d_buf, sizeof(int));
526                 } else if (strcmp(shname, "maps") == 0) {
527                         int j;
528 
529                         maps_shndx = i;
530                         data_maps = data;
531                         for (j = 0; j < MAX_MAPS; j++)
532                                 map_data[j].fd = -1;
533                 } else if (shdr.sh_type == SHT_SYMTAB) {
534                         strtabidx = shdr.sh_link;
535                         symbols = data;
536                 }
537         }
538 
539         ret = 1;
540 
541         if (!symbols) {
542                 printf("missing SHT_SYMTAB section\n");
543                 goto done;
544         }
545 
546         if (data_maps) {
547                 nr_maps = load_elf_maps_section(map_data, maps_shndx,
548                                                 elf, symbols, strtabidx);
549                 if (nr_maps < 0) {
550                         printf("Error: Failed loading ELF maps (errno:%d):%s\n",
551                                nr_maps, strerror(-nr_maps));
552                         ret = 1;
553                         goto done;
554                 }
555                 if (load_maps(map_data, nr_maps, fixup_map))
556                         goto done;
557                 map_data_count = nr_maps;
558 
559                 processed_sec[maps_shndx] = true;
560         }
561 
562         /* process all relo sections, and rewrite bpf insns for maps */
563         for (i = 1; i < ehdr.e_shnum; i++) {
564                 if (processed_sec[i])
565                         continue;
566 
567                 if (get_sec(elf, i, &ehdr, &shname, &shdr, &data))
568                         continue;
569 
570                 if (shdr.sh_type == SHT_REL) {
571                         struct bpf_insn *insns;
572 
573                         /* locate prog sec that need map fixup (relocations) */
574                         if (get_sec(elf, shdr.sh_info, &ehdr, &shname_prog,
575                                     &shdr_prog, &data_prog))
576                                 continue;
577 
578                         if (shdr_prog.sh_type != SHT_PROGBITS ||
579                             !(shdr_prog.sh_flags & SHF_EXECINSTR))
580                                 continue;
581 
582                         insns = (struct bpf_insn *) data_prog->d_buf;
583                         processed_sec[i] = true; /* relo section */
584 
585                         if (parse_relo_and_apply(data, symbols, &shdr, insns,
586                                                  map_data, nr_maps))
587                                 continue;
588                 }
589         }
590 
591         /* load programs */
592         for (i = 1; i < ehdr.e_shnum; i++) {
593 
594                 if (processed_sec[i])
595                         continue;
596 
597                 if (get_sec(elf, i, &ehdr, &shname, &shdr, &data))
598                         continue;
599 
600                 if (memcmp(shname, "kprobe/", 7) == 0 ||
601                     memcmp(shname, "kretprobe/", 10) == 0 ||
602                     memcmp(shname, "tracepoint/", 11) == 0 ||
603                     memcmp(shname, "raw_tracepoint/", 15) == 0 ||
604                     memcmp(shname, "xdp", 3) == 0 ||
605                     memcmp(shname, "perf_event", 10) == 0 ||
606                     memcmp(shname, "socket", 6) == 0 ||
607                     memcmp(shname, "cgroup/", 7) == 0 ||
608                     memcmp(shname, "sockops", 7) == 0 ||
609                     memcmp(shname, "sk_skb", 6) == 0 ||
610                     memcmp(shname, "sk_msg", 6) == 0) {
611                         ret = load_and_attach(shname, data->d_buf,
612                                               data->d_size);
613                         if (ret != 0)
614                                 goto done;
615                 }
616         }
617 
618         ret = 0;
619 done:
620         close(fd);
621         return ret;
622 }
623 
624 int load_bpf_file(char *path)
625 {
626         return do_load_bpf_file(path, NULL);
627 }
628 
629 int load_bpf_file_fixup_map(const char *path, fixup_map_cb fixup_map)
630 {
631         return do_load_bpf_file(path, fixup_map);
632 }
633 
634 void read_trace_pipe(void)
635 {
636         int trace_fd;
637 
638         trace_fd = open(DEBUGFS "trace_pipe", O_RDONLY, 0);
639         if (trace_fd < 0)
640                 return;
641 
642         while (1) {
643                 static char buf[4096];
644                 ssize_t sz;
645 
646                 sz = read(trace_fd, buf, sizeof(buf));
647                 if (sz > 0) {
648                         buf[sz] = 0;
649                         puts(buf);
650                 }
651         }
652 }
653 
654 #define MAX_SYMS 300000
655 static struct ksym syms[MAX_SYMS];
656 static int sym_cnt;
657 
658 static int ksym_cmp(const void *p1, const void *p2)
659 {
660         return ((struct ksym *)p1)->addr - ((struct ksym *)p2)->addr;
661 }
662 
663 int load_kallsyms(void)
664 {
665         FILE *f = fopen("/proc/kallsyms", "r");
666         char func[256], buf[256];
667         char symbol;
668         void *addr;
669         int i = 0;
670 
671         if (!f)
672                 return -ENOENT;
673 
674         while (!feof(f)) {
675                 if (!fgets(buf, sizeof(buf), f))
676                         break;
677                 if (sscanf(buf, "%p %c %s", &addr, &symbol, func) != 3)
678                         break;
679                 if (!addr)
680                         continue;
681                 syms[i].addr = (long) addr;
682                 syms[i].name = strdup(func);
683                 i++;
684         }
685         sym_cnt = i;
686         qsort(syms, sym_cnt, sizeof(struct ksym), ksym_cmp);
687         return 0;
688 }
689 
690 struct ksym *ksym_search(long key)
691 {
692         int start = 0, end = sym_cnt;
693         int result;
694 
695         while (start < end) {
696                 size_t mid = start + (end - start) / 2;
697 
698                 result = key - syms[mid].addr;
699                 if (result < 0)
700                         end = mid;
701                 else if (result > 0)
702                         start = mid + 1;
703                 else
704                         return &syms[mid];
705         }
706 
707         if (start >= 1 && syms[start - 1].addr < key &&
708             key < syms[start].addr)
709                 /* valid ksym */
710                 return &syms[start - 1];
711 
712         /* out of range. return _stext */
713         return &syms[0];
714 }
715 
716 

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