tests/utils/testapp/gen-syscall-events-callstack/gen-syscall-events-callstack.c

   1 /*
   2  * Copyright (C) - 2017 Francis Deslauriers <francis.deslauriers@efficios.com>
   3  *
   4  * This library is free software; you can redistribute it and/or modify it
   5  * under the terms of the GNU Lesser General Public License as published by the
   6  * Free Software Foundation; version 2.1 of the License.
   7  *
   8  * This library is distributed in the hope that it will be useful, but WITHOUT
   9  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  10  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License
  11  * for more details.
  12  *
  13  * You should have received a copy of the GNU Lesser General Public License
  14  * along with this library; if not, write to the Free Software Foundation,
  15  * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301 USA
  16  */
  17
  18 #include <fcntl.h>
  19 #include <signal.h>
  20 #include <stdbool.h>
  21 #include <stdio.h>
  22 #include <stdlib.h>
  23 #include <string.h>
  24 #include <sys/syscall.h>
  25 #include <sys/types.h>
  26 #include <unistd.h>
  27
  28 #include "utils.h"
  29
  30 /**
  31  * The process waits for the creation of a file passed as argument from an
  32  * external processes to execute a syscall and exiting. This is useful for tests
  33  * in combinaison with LTTng's PID tracker feature where we can trace the kernel
  34  * events generated by our test process only.
  35  */
  36
  37 volatile int val = 0;
  38
  39 long __attribute__ ((noinline))
  40 my_gettid(void)
  41 {
  42     long ret;
  43 #ifdef __x86_64
  44     asm volatile
  45     (
  46         "syscall"
  47         : "=a" (ret)
  48         : "0"(__NR_gettid)
  49         : "cc", "rcx", "r11", "memory"
  50     );
  51 #elif __i386
  52     asm volatile
  53     (
  54         "int $0x80"
  55         : "=a" (ret)
  56         : "0"(__NR_gettid)
  57         : "cc", "edi", "esi", "memory"
  58     );
  59 #else
  60 #error "Userspace callstack test not supported for this architecture."
  61 #endif
  62     return ret;
  63 }
  64
  65 int __attribute__ ((noinline))
  66 fct_c(void)
  67 {
  68         return my_gettid();
  69 }
  70
  71 int __attribute__ ((noinline))
  72 fct_b(void)
  73 {
  74         val += fct_c();
  75         return val;
  76 }
  77
  78 int __attribute__ ((noinline))
  79 fct_a(void)
  80 {
  81         val += fct_b();
  82         return val;
  83 }
  84
  85 int main(int argc, char **argv)
  86 {
  87         int ret = 0;
  88         char *start_file;
  89
  90         if (argc != 2) {
  91                 fprintf(stderr, "Error: Missing argument\n");
  92                 fprintf(stderr, "USAGE: %s PATH_WAIT_FILE\n", argv[0]);
  93                 ret = -1;
  94                 goto error;
  95         }
  96
  97         start_file = argv[1];
  98
  99         /*
 100          * Wait for the start_file to be created by an external process
 101          * (typically the test script) before executing the syscall
 102          */
 103         ret = wait_on_file(start_file);
 104         if (ret != 0) {
 105                 goto error;
 106         }
 107
 108         /* Start the callchain to the syscall */
 109         ret = fct_a();
 110
 111         /* Return success */
 112         if (ret >= 0) {
 113                 ret = 0;
 114         }
 115
 116 error:
 117         return ret;
 118 }