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 #if defined(__clang__)
  38 #define nooptimization __attribute__((noinline)) __attribute__((optnone))
  39 #else
  40 #define nooptimization __attribute__((noinline)) __attribute__((optimize(0)))
  41 #endif
  42
  43 volatile int val = 0;
  44
  45 long nooptimization
  46 my_gettid(void)
  47 {
  48     long ret;
  49 #ifdef __x86_64
  50     asm volatile
  51     (
  52         "syscall"
  53         : "=a" (ret)
  54         : "0"(__NR_gettid)
  55         : "cc", "rcx", "r11", "memory"
  56     );
  57 #elif __i386
  58     asm volatile
  59     (
  60         "int $0x80"
  61         : "=a" (ret)
  62         : "0"(__NR_gettid)
  63         : "cc", "edi", "esi", "memory"
  64     );
  65 #else
  66 #error "Userspace callstack test not supported for this architecture."
  67 #endif
  68     return ret;
  69 }
  70
  71 int nooptimization
  72 fct_c(void)
  73 {
  74         return my_gettid();
  75 }
  76
  77 int nooptimization
  78 fct_b(void)
  79 {
  80         val += fct_c();
  81         return val;
  82 }
  83
  84 int nooptimization
  85 fct_a(void)
  86 {
  87         val += fct_b();
  88         return val;
  89 }
  90
  91 int main(int argc, char **argv)
  92 {
  93         int ret = 0;
  94         char *start_file;
  95
  96         if (argc != 2) {
  97                 fprintf(stderr, "Error: Missing argument\n");
  98                 fprintf(stderr, "USAGE: %s PATH_WAIT_FILE\n", argv[0]);
  99                 ret = -1;
 100                 goto error;
 101         }
 102
 103         start_file = argv[1];
 104
 105         /*
 106          * Wait for the start_file to be created by an external process
 107          * (typically the test script) before executing the syscall
 108          */
 109         ret = wait_on_file(start_file);
 110         if (ret != 0) {
 111                 goto error;
 112         }
 113
 114         /* Start the callchain to the syscall */
 115         ret = fct_a();
 116
 117         /* Return success */
 118         if (ret >= 0) {
 119                 ret = 0;
 120         }
 121
 122 error:
 123         return ret;
 124 }