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  * SPDX-License-Identifier: LGPL-2.1-only
   5  *
   6  */
   7
   8 #include <fcntl.h>
   9 #include <signal.h>
  10 #include <stdbool.h>
  11 #include <stdio.h>
  12 #include <stdlib.h>
  13 #include <string.h>
  14 #include <sys/syscall.h>
  15 #include <sys/types.h>
  16 #include <unistd.h>
  17
  18 #include "utils.h"
  19
  20 /**
  21  * The process waits for the creation of a file passed as argument from an
  22  * external processes to execute a syscall and exiting. This is useful for tests
  23  * in combinaison with LTTng's PID tracker feature where we can trace the kernel
  24  * events generated by our test process only.
  25  */
  26
  27 #if defined(__clang__)
  28 #define nooptimization __attribute__((noinline)) __attribute__((optnone))
  29 #else
  30 #define nooptimization __attribute__((noinline)) __attribute__((optimize(0)))
  31 #endif
  32
  33 volatile int val = 0;
  34
  35 long nooptimization my_gettid(void);
  36 long nooptimization
  37 my_gettid(void)
  38 {
  39     long ret;
  40 #ifdef __x86_64
  41     asm volatile
  42     (
  43         "syscall"
  44         : "=a" (ret)
  45         : "0"(__NR_gettid)
  46         : "cc", "rcx", "r11", "memory"
  47     );
  48 #elif __i386
  49     asm volatile
  50     (
  51         "int $0x80"
  52         : "=a" (ret)
  53         : "0"(__NR_gettid)
  54         : "cc", "edi", "esi", "memory"
  55     );
  56 #else
  57 #error "Userspace callstack test not supported for this architecture."
  58 #endif
  59     return ret;
  60 }
  61
  62 int nooptimization fct_c(void);
  63 int nooptimization
  64 fct_c(void)
  65 {
  66         return my_gettid();
  67 }
  68
  69 int nooptimization fct_b(void);
  70 int nooptimization
  71 fct_b(void)
  72 {
  73         val += fct_c();
  74         return val;
  75 }
  76
  77 int nooptimization fct_a(void);
  78 int nooptimization
  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 }