usertrace/lttng_usertrace.c

   1
   2 /* LTTng user-space tracing code
   3  *
   4  * Copyright 2006 Mathieu Desnoyers
   5  *
   6  */
   7
   8
   9 #include <sys/types.h>
  10 #include <sys/wait.h>
  11 #include <unistd.h>
  12 #include <stdlib.h>
  13 #include <stdio.h>
  14 #include <signal.h>
  15 #include <syscall.h>
  16 #include <features.h>
  17 #include <pthread.h>
  18 #include <malloc.h>
  19 #include <string.h>
  20
  21 #include <asm/atomic.h>
  22 #include "lttng_usertrace.h"
  23
  24 #define MAX_TRACES 16
  25
  26 struct ltt_buf {
  27         void *start;
  28         atomic_t        offset;
  29         atomic_t        reserve_count;
  30         atomic_t        commit_count;
  31
  32         atomic_t        events_lost;
  33 };
  34
  35 struct lttng_trace_info {
  36         int     active:1;
  37         struct {
  38                 struct ltt_buf facilities;
  39                 struct ltt_buf cpu;
  40         } channel;
  41 };
  42
  43
  44 /* TLS for the trace info */
  45 /* http://www.dis.com/gnu/gcc/C--98-Thread-Local-Edits.html
  46  *
  47  * Add after paragraph 4
  48  *
  49  *     The storage for an object of thread storage duration shall be statically
  50  *     initialized before the first statement of the thread startup function. An
  51  *     object of thread storage duration shall not require dynamic
  52  *     initialization.
  53  * GCC extention permits init of a range.
  54  */
  55
  56 static __thread struct lttng_trace_info lttng_trace_info[MAX_TRACES] =
  57 {       [ 0 ... MAX_TRACES-1 ].active = 0,
  58         [ 0 ... MAX_TRACES-1 ].channel =
  59                 { NULL,
  60                         ATOMIC_INIT(0),
  61                         ATOMIC_INIT(0),
  62                         ATOMIC_INIT(0),
  63                         ATOMIC_INIT(0),
  64                         ATOMIC_INIT(0)
  65                 }
  66 };
  67
  68 /* signal handler */
  69 void __lttng_sig_trace_handler(int signo)
  70 {
  71         int ret;
  72         sigset_t set, oldset;
  73
  74   printf("LTTng Sig handler : pid : %lu\n", getpid());
  75
  76         /* Disable signals */
  77         ret = sigfillset(&set);
  78         if(ret) {
  79                 printf("Error in sigfillset\n");
  80                 exit(1);
  81         }
  82
  83         ret = sigprocmask(SIG_BLOCK, &set, &oldset);
  84         if(ret) {
  85                 printf("Error in sigprocmask\n");
  86                 exit(1);
  87         }
  88
  89         /* Get all the new traces */
  90 #if 0
  91         do {
  92                 /* FIXME : allocate the trace structure somewhere : thread private */
  93                 ret = ltt_update(addr, &active, &filter);
  94
  95                 if(ret) {
  96                         printf("Error in ltt_update system call\n");
  97                         exit(1);
  98                 }
  99         } while(addr);
 100
 101 #endif //0
 102         /* Enable signals */
 103         ret = sigprocmask(SIG_SETMASK, &oldset, NULL);
 104         if(ret) {
 105                 printf("Error in sigprocmask\n");
 106                 exit(1);
 107         }
 108
 109 }
 110
 111
 112 void __lttng_init_trace_info(void)
 113 {
 114         memset(&lttng_trace_info, 0, MAX_TRACES*sizeof(struct lttng_trace_info));
 115 }
 116
 117 void __attribute__((constructor)) __lttng_user_init(void)
 118 {
 119         static struct sigaction act;
 120         int err;
 121
 122   printf("LTTng user init\n");
 123
 124         /* Init trace info */
 125         __lttng_init_trace_info();
 126
 127         /* Activate the signal */
 128         act.sa_handler = __lttng_sig_trace_handler;
 129         err = sigemptyset(&(act.sa_mask));
 130         if(err) perror("Error with sigemptyset");
 131         err = sigaddset(&(act.sa_mask), SIGRTMIN+3);
 132         if(err) perror("Error with sigaddset");
 133         err = sigaction(SIGRTMIN+3, &act, NULL);
 134         if(err) perror("Error with sigaction");
 135
 136         /* TEST */
 137         err = ltt_switch((unsigned long)NULL);
 138         if(err) {
 139                 printf("Error in ltt_switch system call\n");
 140                 exit(1);
 141         }
 142
 143         /* Make the first ltt_update system call */
 144         err = ltt_update(1, NULL, NULL);
 145         if(err) {
 146                 printf("Error in ltt_update system call\n");
 147                 exit(1);
 148         }
 149
 150         /* Make some ltt_switch syscalls */
 151         err = ltt_switch((unsigned long)NULL);
 152         if(err) {
 153                 printf("Error in ltt_switch system call\n");
 154                 exit(1);
 155         }
 156
 157
 158
 159 }