The Tcpdump Group git mirrors - tcpdump/blob - instrument-functions.c

   1 /*
   2  * Redistribution and use in source and binary forms, with or without
   3  * modification, are permitted provided that: (1) source code
   4  * distributions retain the above copyright notice and this paragraph
   5  * in its entirety, and (2) distributions including binary code include
   6  * the above copyright notice and this paragraph in its entirety in
   7  * the documentation or other materials provided with the distribution.
   8  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND
   9  * WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, WITHOUT
  10  * LIMITATION, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  11  * FOR A PARTICULAR PURPOSE.
  12  */
  13
  14 #include <stdio.h>
  15 #include <string.h>
  16 #include <stdlib.h>
  17 #include <sys/types.h>
  18 #include <sys/stat.h>
  19 #include <unistd.h>
  20 #include <bfd.h>
  21
  22 /*
  23  * Generate instrumentation calls for entry and exit to functions.
  24  * Just after function entry and just before function exit, the
  25  * following profiling functions are called with the address of the
  26  * current function and its call site (currently not use).
  27  *
  28  * The attribute 'no_instrument_function' causes this instrumentation is
  29  * not done.
  30  *
  31  * These profiling functions call print_debug(). This function prints the
  32  * current function name with indentation and call level.
  33  * If entering in a function it prints also the calling function name with
  34  * file name and line number.
  35  *
  36  * To configure the printing of only the global functions names:
  37  * $ make instrument_global
  38  *
  39  * To go back to print all the functions names:
  40  * $ make instrument_all
  41  *
  42  * To print nothing, like with no instrumentation:
  43  * $ make instrument_off
  44  */
  45
  46 #define ND_NO_INSTRUMENT __attribute__((no_instrument_function))
  47
  48 /* Store the function call level, used also in pretty_print_packet() */
  49 extern int profile_func_level;
  50 int profile_func_level = -1;
  51
  52 typedef enum {
  53         ENTER,
  54         EXIT
  55 } action_type;
  56
  57 void __cyg_profile_func_enter(void *this_fn, void *call_site) ND_NO_INSTRUMENT;
  58
  59 void __cyg_profile_func_exit(void *this_fn, void *call_site) ND_NO_INSTRUMENT;
  60
  61 static void print_debug(void *this_fn, void *call_site, action_type action)
  62         ND_NO_INSTRUMENT;
  63
  64 void
  65 __cyg_profile_func_enter(void *this_fn, void *call_site)
  66 {
  67         print_debug(this_fn, call_site, ENTER);
  68 }
  69
  70 void
  71 __cyg_profile_func_exit(void *this_fn, void *call_site)
  72 {
  73         print_debug(this_fn, call_site, EXIT);
  74 }
  75
  76 /* If this file exists, print only the global functions */
  77 #define ND_FILE_FLAG_GLOBAL "instrument_functions_global.devel"
  78
  79 /* If this file exists, print nothing, like with no instrumentation */
  80 #define ND_FILE_FLAG_OFF "instrument_functions_off.devel"
  81
  82 static void print_debug(void *this_fn, void *call_site, action_type action)
  83 {
  84         static bfd* abfd;
  85         static asymbol **symtab;
  86         static long symcount;
  87         static asection *text;
  88         static bfd_vma vma;
  89         static int instrument_off;
  90         static int print_only_global;
  91         symbol_info syminfo;
  92         struct stat statbuf;
  93         int i;
  94
  95         if (!instrument_off) {
  96                 /* one-time test */
  97                 if (!stat(ND_FILE_FLAG_OFF, &statbuf)) {
  98                         instrument_off = 1;
  99                         return;
 100                 }
 101         } else
 102                 return;
 103
 104         /* If no errors, this block should be executed one time */
 105         if (!abfd) {
 106                 char pgm_name[1024];
 107                 long symsize;
 108
 109                 if (!stat(ND_FILE_FLAG_GLOBAL, &statbuf))
 110                         print_only_global = 1;
 111
 112                 ssize_t ret = readlink("/proc/self/exe", pgm_name, sizeof(pgm_name));
 113                 if (ret == -1) {
 114                         perror("failed to find executable\n");
 115                         return;
 116                 }
 117                 pgm_name[ret] = 0;
 118
 119                 bfd_init();
 120
 121                 abfd = bfd_openr(pgm_name, NULL);
 122                 if (!abfd) {
 123                         bfd_perror("bfd_openr");
 124                         return;
 125                 }
 126
 127                 if (!bfd_check_format(abfd, bfd_object)) {
 128                         bfd_perror("bfd_check_format");
 129                         return;
 130                 }
 131
 132                 if((symsize = bfd_get_symtab_upper_bound(abfd)) == -1) {
 133                         bfd_perror("bfd_get_symtab_upper_bound");
 134                         return;
 135                 }
 136
 137                 symtab = (asymbol **)malloc(symsize);
 138                 symcount = bfd_canonicalize_symtab(abfd, symtab);
 139                 if (symcount < 0) {
 140                         free (symtab);
 141                         bfd_perror ("bfd_canonicalize_symtab");
 142                         return;
 143                 }
 144
 145                 if ((text = bfd_get_section_by_name(abfd, ".text")) == NULL) {
 146                         bfd_perror("bfd_get_section_by_name");
 147                         return;
 148                 }
 149                 vma = text->vma;
 150         }
 151
 152         if (print_only_global) {
 153                 int found;
 154
 155                 i = 0;
 156                 found = 0;
 157                 while (i < symcount && !found) {
 158                         bfd_get_symbol_info(abfd, symtab[i], &syminfo);
 159                         if ((void *)syminfo.value == this_fn) {
 160                                 found = 1;
 161                         }
 162                         i++;
 163                 }
 164                 /* type == 'T' for a global function */
 165                 if (found == 1 && syminfo.type != 'T')
 166                         return;
 167         }
 168
 169         /* Current function */
 170         if ((bfd_vma)this_fn < vma) {
 171                 printf("[ERROR address this_fn]");
 172         } else {
 173                 const char *file;
 174                 const char *func;
 175                 unsigned int line;
 176
 177                 if (!bfd_find_nearest_line(abfd, text, symtab, (bfd_vma)this_fn - vma,
 178                                                                    &file, &func, &line)) {
 179                         printf("[ERROR bfd_find_nearest_line this_fn]");
 180                 } else {
 181                         if (action == ENTER)
 182                                 profile_func_level += 1;
 183                         /* Indentation */
 184                         for (i = 0 ; i < profile_func_level ; i++)
 185                                 putchar(' ');
 186                         if (action == ENTER)
 187                                 printf("[>> ");
 188                         else
 189                                 printf("[<< ");
 190                         /* Function name */
 191                         if (func == NULL || *func == '\0')
 192                                 printf("???");
 193                         else
 194                                 printf("%s", func);
 195                         printf(" (%d)", profile_func_level);
 196                         /* Print the "from" part except for the main function) */
 197                         if (action == ENTER && strncmp(func, "main", sizeof("main"))) {
 198                                 /* Calling function */
 199                                 if ((bfd_vma)call_site < vma) {
 200                                         printf("[ERROR address call_site]");
 201                                 } else {
 202                                         if (!bfd_find_nearest_line(abfd, text, symtab,
 203                                                                                            (bfd_vma)call_site - vma, &file,
 204                                                                                            &func, &line)) {
 205                                                 printf("[ERROR bfd_find_nearest_line call_site]");
 206                                         } else {
 207                                                 printf(" from ");
 208                                                 /* Function name */
 209                                                 if (func == NULL || *func == '\0')
 210                                                         printf("???");
 211                                                 else
 212                                                         printf("%s", func);
 213                                                 /* File name */
 214                                                 if (file == NULL || *file == '\0')
 215                                                         printf(" ??:");
 216                                                 else {
 217                                                         char *slashp = strrchr(file, '/');
 218                                                         if (slashp != NULL)
 219                                                                 file = slashp + 1;
 220                                                         printf(" %s:", file);
 221                                                 }
 222                                                 /* Line number */
 223                                                 if (line == 0)
 224                                                         printf("?");
 225                                                 else
 226                                                         printf("%u", line);
 227                                                 printf("]");
 228                                         }
 229                                 }
 230                         }
 231                         putchar('\n');
 232                         if (action == EXIT)
 233                                 profile_func_level -= 1;
 234                 }
 235         }
 236         fflush(stdout);
 237 }
 238
 239 /* vi: set tabstop=4 softtabstop=0 shiftwidth=4 smarttab autoindent : */