assert.c

 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. */
15static void __attribute__((noinline)) test_dump_stack(void);
16static 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
61static pid_t _gettid(void)
62{
63	return syscall(SYS_gettid);
64}
65
66void __attribute__((noinline))
67test_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}