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 #ifndef _GNU_SOURCE
  15 #define _GNU_SOURCE
  16 #endif
  17
  18 #include <stdio.h>
  19 #include <dlfcn.h>
  20
  21 extern int profile_func_level;
  22 int profile_func_level = -1;
  23
  24 /*
  25  * Generate instrumentation calls for entry and exit to functions.
  26  * Just after function entry and just before function exit, the
  27  * following profiling functions are called with the address of the
  28  * current function and its call site (currently not use).
  29  *
  30  * The attribute 'no_instrument_function' causes this instrumentation is
  31  * not done.
  32  *
  33  * These profiling functions print the function names with indentation
  34  * and call level.
  35  *
  36  * To instument a static function, remove temporarily the static specifier.
  37  */
  38
  39 #ifndef ND_NO_INSTRUMENT
  40 #define ND_NO_INSTRUMENT __attribute__((no_instrument_function))
  41 #endif
  42
  43 void __cyg_profile_func_enter(void *this_fn, void *call_site) ND_NO_INSTRUMENT;
  44
  45 void __cyg_profile_func_exit(void *this_fn, void *call_site) ND_NO_INSTRUMENT;
  46
  47 /*
  48  * Structure table to store the functions data from FILE_NAME.
  49  * FILE_NAME is generated via:
  50  * $ nm $(PROG) | grep ' [tT] '
  51  * or
  52  * $ nm $(PROG) | grep ' [T] '
  53  */
  54
  55 #define MAX_FUNCTIONS 20000
  56 static struct {
  57         void *addr;
  58         char type;
  59         char name[128];
  60 } functions[MAX_FUNCTIONS] ;
  61 static int functions_count;
  62 static int initialization_done;
  63
  64 /*
  65  * Read the result of nm in functions[]
  66  */
  67
  68 #define FILE_NAME "tcpdump_instrument_functions.nm"
  69
  70 void read_functions_table(void) ND_NO_INSTRUMENT;
  71
  72 void
  73 read_functions_table(void)
  74 {
  75         FILE *fp;
  76         int i = 0;
  77         if ((fp = fopen(FILE_NAME, "r")) == NULL) {
  78                 printf("Warning: Cannot open \"%s\" file\n", FILE_NAME);
  79                 return;
  80         }
  81         while (i < MAX_FUNCTIONS && fscanf(fp, "%p %c %s", &functions[i].addr,
  82                       &functions[i].type, functions[i].name) != EOF)
  83                 i++;
  84         fclose(fp);
  85         functions_count = i;
  86 }
  87
  88 /*
  89  * Get the function name by searching in functions[]
  90  */
  91
  92 static const char * get_function_name(void *func) ND_NO_INSTRUMENT;
  93
  94 static const char *
  95 get_function_name(void *func)
  96 {
  97         int i = 0;
  98         int found = 0;
  99         if (!initialization_done) {
 100                 read_functions_table();
 101                 initialization_done = 1;
 102         }
 103         while (i < functions_count) {
 104                 if (functions[i].addr == func) {
 105                         found = 1;
 106                         break;
 107                 }
 108                 i++;
 109         }
 110         if (found)
 111                 return (functions[i].name);
 112         else
 113                 return NULL;
 114 }
 115
 116 void
 117 __cyg_profile_func_enter(void *this_fn,
 118                               void *call_site __attribute__((unused)))
 119 {
 120         int i;
 121         const char *function_name;
 122
 123         if ((function_name = get_function_name(this_fn)) != NULL) {
 124                 profile_func_level += 1;
 125                 for (i = 0 ; i < profile_func_level ; i++)
 126                         putchar(' ');
 127                 printf("[>> %s (%d)]\n", function_name, profile_func_level);
 128         }
 129         fflush(stdout);
 130 }
 131
 132 void
 133 __cyg_profile_func_exit(void *this_fn,
 134                              void *call_site __attribute__((unused)))
 135 {
 136         int i;
 137         const char *function_name;
 138
 139         if ((function_name = get_function_name(this_fn)) != NULL) {
 140                 for (i = 0 ; i < profile_func_level ; i++)
 141                         putchar(' ');
 142                 printf ("[<< %s (%d)]\n", function_name, profile_func_level);
 143                 profile_func_level -= 1;
 144         }
 145         fflush(stdout);
 146 }