contrib/hostapd/src/utils/trace.c

   1 /*
   2  * Backtrace debugging
   3  * Copyright (c) 2009, Jouni Malinen <j@w1.fi>
   4  *
   5  * This software may be distributed under the terms of the BSD license.
   6  * See README for more details.
   7  */
   8
   9 #include "includes.h"
  10
  11 #include "common.h"
  12 #include "trace.h"
  13
  14 #ifdef WPA_TRACE
  15
  16 static struct dl_list active_references =
  17 { &active_references, &active_references };
  18
  19 #ifdef WPA_TRACE_BFD
  20 #include <bfd.h>
  21 #ifdef __linux__
  22 #include <demangle.h>
  23 #else /* __linux__ */
  24 #include <libiberty/demangle.h>
  25 #endif /* __linux__ */
  26
  27 static char *prg_fname = NULL;
  28 static bfd *cached_abfd = NULL;
  29 static asymbol **syms = NULL;
  30
  31 static void get_prg_fname(void)
  32 {
  33         char exe[50], fname[512];
  34         int len;
  35         os_snprintf(exe, sizeof(exe) - 1, "/proc/%u/exe", getpid());
  36         len = readlink(exe, fname, sizeof(fname) - 1);
  37         if (len < 0 || len >= (int) sizeof(fname)) {
  38                 perror("readlink");
  39                 return;
  40         }
  41         fname[len] = '\0';
  42         prg_fname = strdup(fname);
  43 }
  44
  45
  46 static bfd * open_bfd(const char *fname)
  47 {
  48         bfd *abfd;
  49         char **matching;
  50
  51         abfd = bfd_openr(prg_fname, NULL);
  52         if (abfd == NULL) {
  53                 wpa_printf(MSG_INFO, "bfd_openr failed");
  54                 return NULL;
  55         }
  56
  57         if (bfd_check_format(abfd, bfd_archive)) {
  58                 wpa_printf(MSG_INFO, "bfd_check_format failed");
  59                 bfd_close(abfd);
  60                 return NULL;
  61         }
  62
  63         if (!bfd_check_format_matches(abfd, bfd_object, &matching)) {
  64                 wpa_printf(MSG_INFO, "bfd_check_format_matches failed");
  65                 free(matching);
  66                 bfd_close(abfd);
  67                 return NULL;
  68         }
  69
  70         return abfd;
  71 }
  72
  73
  74 static void read_syms(bfd *abfd)
  75 {
  76         long storage, symcount;
  77         bfd_boolean dynamic = FALSE;
  78
  79         if (syms)
  80                 return;
  81
  82         if (!(bfd_get_file_flags(abfd) & HAS_SYMS)) {
  83                 wpa_printf(MSG_INFO, "No symbols");
  84                 return;
  85         }
  86
  87         storage = bfd_get_symtab_upper_bound(abfd);
  88         if (storage == 0) {
  89                 storage = bfd_get_dynamic_symtab_upper_bound(abfd);
  90                 dynamic = TRUE;
  91         }
  92         if (storage < 0) {
  93                 wpa_printf(MSG_INFO, "Unknown symtab upper bound");
  94                 return;
  95         }
  96
  97         syms = malloc(storage);
  98         if (syms == NULL) {
  99                 wpa_printf(MSG_INFO, "Failed to allocate memory for symtab "
 100                            "(%ld bytes)", storage);
 101                 return;
 102         }
 103         if (dynamic)
 104                 symcount = bfd_canonicalize_dynamic_symtab(abfd, syms);
 105         else
 106                 symcount = bfd_canonicalize_symtab(abfd, syms);
 107         if (symcount < 0) {
 108                 wpa_printf(MSG_INFO, "Failed to canonicalize %ssymtab",
 109                            dynamic ? "dynamic " : "");
 110                 free(syms);
 111                 syms = NULL;
 112                 return;
 113         }
 114 }
 115
 116
 117 struct bfd_data {
 118         bfd_vma pc;
 119         bfd_boolean found;
 120         const char *filename;
 121         const char *function;
 122         unsigned int line;
 123 };
 124
 125
 126 static void find_addr_sect(bfd *abfd, asection *section, void *obj)
 127 {
 128         struct bfd_data *data = obj;
 129         bfd_vma vma;
 130         bfd_size_type size;
 131
 132         if (data->found)
 133                 return;
 134
 135         if (!(bfd_get_section_vma(abfd, section)))
 136                 return;
 137
 138         vma = bfd_get_section_vma(abfd, section);
 139         if (data->pc < vma)
 140                 return;
 141
 142         size = bfd_get_section_size(section);
 143         if (data->pc >= vma + size)
 144                 return;
 145
 146         data->found = bfd_find_nearest_line(abfd, section, syms,
 147                                             data->pc - vma,
 148                                             &data->filename,
 149                                             &data->function,
 150                                             &data->line);
 151 }
 152
 153
 154 static void wpa_trace_bfd_addr(void *pc)
 155 {
 156         bfd *abfd = cached_abfd;
 157         struct bfd_data data;
 158         const char *name;
 159         char *aname = NULL;
 160         const char *filename;
 161
 162         if (abfd == NULL)
 163                 return;
 164
 165         data.pc = (bfd_vma) pc;
 166         data.found = FALSE;
 167         bfd_map_over_sections(abfd, find_addr_sect, &data);
 168
 169         if (!data.found)
 170                 return;
 171
 172         do {
 173                 if (data.function)
 174                         aname = bfd_demangle(abfd, data.function,
 175                                              DMGL_ANSI | DMGL_PARAMS);
 176                 name = aname ? aname : data.function;
 177                 filename = data.filename;
 178                 if (filename) {
 179                         char *end = os_strrchr(filename, '/');
 180                         int i = 0;
 181                         while (*filename && *filename == prg_fname[i] &&
 182                                filename <= end) {
 183                                 filename++;
 184                                 i++;
 185                         }
 186                 }
 187                 wpa_printf(MSG_INFO, "     %s() %s:%u",
 188                            name, filename, data.line);
 189                 free(aname);
 190
 191                 data.found = bfd_find_inliner_info(abfd, &data.filename,
 192                                                    &data.function, &data.line);
 193         } while (data.found);
 194 }
 195
 196
 197 static const char * wpa_trace_bfd_addr2func(void *pc)
 198 {
 199         bfd *abfd = cached_abfd;
 200         struct bfd_data data;
 201
 202         if (abfd == NULL)
 203                 return NULL;
 204
 205         data.pc = (bfd_vma) pc;
 206         data.found = FALSE;
 207         bfd_map_over_sections(abfd, find_addr_sect, &data);
 208
 209         if (!data.found)
 210                 return NULL;
 211
 212         return data.function;
 213 }
 214
 215
 216 static void wpa_trace_bfd_init(void)
 217 {
 218         if (!prg_fname) {
 219                 get_prg_fname();
 220                 if (!prg_fname)
 221                         return;
 222         }
 223
 224         if (!cached_abfd) {
 225                 cached_abfd = open_bfd(prg_fname);
 226                 if (!cached_abfd) {
 227                         wpa_printf(MSG_INFO, "Failed to open bfd");
 228                         return;
 229                 }
 230         }
 231
 232         read_syms(cached_abfd);
 233         if (!syms) {
 234                 wpa_printf(MSG_INFO, "Failed to read symbols");
 235                 return;
 236         }
 237 }
 238
 239
 240 void wpa_trace_dump_funcname(const char *title, void *pc)
 241 {
 242         wpa_printf(MSG_INFO, "WPA_TRACE: %s: %p", title, pc);
 243         wpa_trace_bfd_init();
 244         wpa_trace_bfd_addr(pc);
 245 }
 246
 247 #else /* WPA_TRACE_BFD */
 248
 249 #define wpa_trace_bfd_init() do { } while (0)
 250 #define wpa_trace_bfd_addr(pc) do { } while (0)
 251 #define wpa_trace_bfd_addr2func(pc) NULL
 252
 253 #endif /* WPA_TRACE_BFD */
 254
 255 void wpa_trace_dump_func(const char *title, void **btrace, int btrace_num)
 256 {
 257         char **sym;
 258         int i;
 259         enum { TRACE_HEAD, TRACE_RELEVANT, TRACE_TAIL } state;
 260
 261         wpa_trace_bfd_init();
 262         wpa_printf(MSG_INFO, "WPA_TRACE: %s - START", title);
 263         sym = backtrace_symbols(btrace, btrace_num);
 264         state = TRACE_HEAD;
 265         for (i = 0; i < btrace_num; i++) {
 266                 const char *func = wpa_trace_bfd_addr2func(btrace[i]);
 267                 if (state == TRACE_HEAD && func &&
 268                     (os_strcmp(func, "wpa_trace_add_ref_func") == 0 ||
 269                      os_strcmp(func, "wpa_trace_check_ref") == 0 ||
 270                      os_strcmp(func, "wpa_trace_show") == 0))
 271                         continue;
 272                 if (state == TRACE_TAIL && sym && sym[i] &&
 273                     os_strstr(sym[i], "__libc_start_main"))
 274                         break;
 275                 if (state == TRACE_HEAD)
 276                         state = TRACE_RELEVANT;
 277                 if (sym)
 278                         wpa_printf(MSG_INFO, "[%d]: %s", i, sym[i]);
 279                 else
 280                         wpa_printf(MSG_INFO, "[%d]: ?? [%p]", i, btrace[i]);
 281                 wpa_trace_bfd_addr(btrace[i]);
 282                 if (state == TRACE_RELEVANT && func &&
 283                     os_strcmp(func, "main") == 0)
 284                         state = TRACE_TAIL;
 285         }
 286         free(sym);
 287         wpa_printf(MSG_INFO, "WPA_TRACE: %s - END", title);
 288 }
 289
 290
 291 void wpa_trace_show(const char *title)
 292 {
 293         struct info {
 294                 WPA_TRACE_INFO
 295         } info;
 296         wpa_trace_record(&info);
 297         wpa_trace_dump(title, &info);
 298 }
 299
 300
 301 void wpa_trace_add_ref_func(struct wpa_trace_ref *ref, const void *addr)
 302 {
 303         if (addr == NULL)
 304                 return;
 305         ref->addr = addr;
 306         wpa_trace_record(ref);
 307         dl_list_add(&active_references, &ref->list);
 308 }
 309
 310
 311 void wpa_trace_check_ref(const void *addr)
 312 {
 313         struct wpa_trace_ref *ref;
 314         dl_list_for_each(ref, &active_references, struct wpa_trace_ref, list) {
 315                 if (addr != ref->addr)
 316                         continue;
 317                 wpa_trace_show("Freeing referenced memory");
 318                 wpa_trace_dump("Reference registration", ref);
 319                 abort();
 320         }
 321 }
 322
 323 #endif /* WPA_TRACE */