1  // SPDX-License-Identifier: GPL-2.0-only
2  /*
3   * tools/testing/selftests/kvm/lib/assert.c
4   *
5   * Copyright (C) 2018, Google LLC.
6   */
7  #include "test_util.h"
8  
9  #include <execinfo.h>
10  #include <sys/syscall.h>
11  
12  #include "kselftest.h"
13  
14  /* Dumps the current stack trace to stderr. */
15  static void __attribute__((noinline)) test_dump_stack(void);
test_dump_stack(void)16  static void test_dump_stack(void)
17  {
18  	/*
19  	 * Build and run this command:
20  	 *
21  	 *	addr2line -s -e /proc/$PPID/exe -fpai {backtrace addresses} | \
22  	 *		cat -n 1>&2
23  	 *
24  	 * Note that the spacing is different and there's no newline.
25  	 */
26  	size_t i;
27  	size_t n = 20;
28  	void *stack[n];
29  	const char *addr2line = "addr2line -s -e /proc/$PPID/exe -fpai";
30  	const char *pipeline = "|cat -n 1>&2";
31  	char cmd[strlen(addr2line) + strlen(pipeline) +
32  		 /* N bytes per addr * 2 digits per byte + 1 space per addr: */
33  		 n * (((sizeof(void *)) * 2) + 1) +
34  		 /* Null terminator: */
35  		 1];
36  	char *c = cmd;
37  
38  	n = backtrace(stack, n);
39  	/*
40  	 * Skip the first 2 frames, which should be test_dump_stack() and
41  	 * test_assert(); both of which are declared noinline.  Bail if the
42  	 * resulting stack trace would be empty. Otherwise, addr2line will block
43  	 * waiting for addresses to be passed in via stdin.
44  	 */
45  	if (n <= 2) {
46  		fputs("  (stack trace empty)\n", stderr);
47  		return;
48  	}
49  
50  	c += sprintf(c, "%s", addr2line);
51  	for (i = 2; i < n; i++)
52  		c += sprintf(c, " %lx", ((unsigned long) stack[i]) - 1);
53  
54  	c += sprintf(c, "%s", pipeline);
55  #pragma GCC diagnostic push
56  #pragma GCC diagnostic ignored "-Wunused-result"
57  	system(cmd);
58  #pragma GCC diagnostic pop
59  }
60  
_gettid(void)61  static pid_t _gettid(void)
62  {
63  	return syscall(SYS_gettid);
64  }
65  
66  void __attribute__((noinline))
test_assert(bool exp,const char * exp_str,const char * file,unsigned int line,const char * fmt,...)67  test_assert(bool exp, const char *exp_str,
68  	const char *file, unsigned int line, const char *fmt, ...)
69  {
70  	va_list ap;
71  
72  	if (!(exp)) {
73  		va_start(ap, fmt);
74  
75  		fprintf(stderr, "==== Test Assertion Failure ====\n"
76  			"  %s:%u: %s\n"
77  			"  pid=%d tid=%d errno=%d - %s\n",
78  			file, line, exp_str, getpid(), _gettid(),
79  			errno, strerror(errno));
80  		test_dump_stack();
81  		if (fmt) {
82  			fputs("  ", stderr);
83  			vfprintf(stderr, fmt, ap);
84  			fputs("\n", stderr);
85  		}
86  		va_end(ap);
87  
88  		if (errno == EACCES) {
89  			print_skip("Access denied - Exiting");
90  			exit(KSFT_SKIP);
91  		}
92  		exit(254);
93  	}
94  
95  	return;
96  }
97