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 my_gettid(void);
  46 long nooptimization
  47 my_gettid(void)
  48 {
  49     long ret;
  50 #ifdef __x86_64
  51     asm volatile
  52     (
  53         "syscall"
  54         : "=a" (ret)
  55         : "0"(__NR_gettid)
  56         : "cc", "rcx", "r11", "memory"
  57     );
  58 #elif __i386
  59     asm volatile
  60     (
  61         "int $0x80"
  62         : "=a" (ret)
  63         : "0"(__NR_gettid)
  64         : "cc", "edi", "esi", "memory"
  65     );
  66 #else
  67 #error "Userspace callstack test not supported for this architecture."
  68 #endif
  69     return ret;
  70 }
  71
  72 int nooptimization fct_c(void);
  73 int nooptimization
  74 fct_c(void)
  75 {
  76         return my_gettid();
  77 }
  78
  79 int nooptimization fct_b(void);
  80 int nooptimization
  81 fct_b(void)
  82 {
  83         val += fct_c();
  84         return val;
  85 }
  86
  87 int nooptimization fct_a(void);
  88 int nooptimization
  89 fct_a(void)
  90 {
  91         val += fct_b();
  92         return val;
  93 }
  94
  95 int main(int argc, char **argv)
  96 {
  97         int ret = 0;
  98         char *start_file;
  99
 100         if (argc != 2) {
 101                 fprintf(stderr, "Error: Missing argument\n");
 102                 fprintf(stderr, "USAGE: %s PATH_WAIT_FILE\n", argv[0]);
 103                 ret = -1;
 104                 goto error;
 105         }
 106
 107         start_file = argv[1];
 108
 109         /*
 110          * Wait for the start_file to be created by an external process
 111          * (typically the test script) before executing the syscall
 112          */
 113         ret = wait_on_file(start_file);
 114         if (ret != 0) {
 115                 goto error;
 116         }
 117
 118         /* Start the callchain to the syscall */
 119         ret = fct_a();
 120
 121         /* Return success */
 122         if (ret >= 0) {
 123                 ret = 0;
 124         }
 125
 126 error:
 127         return ret;
 128 }