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
8#define _GNU_SOURCE /* for getline(3) and strchrnul(3)*/
9
10#include "test_util.h"
11
12#include <execinfo.h>
13#include <sys/syscall.h>
14
15#include "kselftest.h"
16
17/* Dumps the current stack trace to stderr. */
18static void __attribute__((noinline)) test_dump_stack(void);
19static void test_dump_stack(void)
20{
21	/*
22	 * Build and run this command:
23	 *
24	 *	addr2line -s -e /proc/$PPID/exe -fpai {backtrace addresses} | \
25	 *		cat -n 1>&2
26	 *
27	 * Note that the spacing is different and there's no newline.
28	 */
29	size_t i;
30	size_t n = 20;
31	void *stack[n];
32	const char *addr2line = "addr2line -s -e /proc/$PPID/exe -fpai";
33	const char *pipeline = "|cat -n 1>&2";
34	char cmd[strlen(addr2line) + strlen(pipeline) +
35		 /* N bytes per addr * 2 digits per byte + 1 space per addr: */
36		 n * (((sizeof(void *)) * 2) + 1) +
37		 /* Null terminator: */
38		 1];
39	char *c = cmd;
40
41	n = backtrace(stack, n);
42	/*
43	 * Skip the first 2 frames, which should be test_dump_stack() and
44	 * test_assert(); both of which are declared noinline.  Bail if the
45	 * resulting stack trace would be empty. Otherwise, addr2line will block
46	 * waiting for addresses to be passed in via stdin.
47	 */
48	if (n <= 2) {
49		fputs("  (stack trace empty)\n", stderr);
50		return;
51	}
52
53	c += sprintf(c, "%s", addr2line);
54	for (i = 2; i < n; i++)
55		c += sprintf(c, " %lx", ((unsigned long) stack[i]) - 1);
56
57	c += sprintf(c, "%s", pipeline);
58#pragma GCC diagnostic push
59#pragma GCC diagnostic ignored "-Wunused-result"
60	system(cmd);
61#pragma GCC diagnostic pop
62}
63
64static pid_t _gettid(void)
65{
66	return syscall(SYS_gettid);
67}
68
69void __attribute__((noinline))
70test_assert(bool exp, const char *exp_str,
71	const char *file, unsigned int line, const char *fmt, ...)
72{
73	va_list ap;
74
75	if (!(exp)) {
76		va_start(ap, fmt);
77
78		fprintf(stderr, "==== Test Assertion Failure ====\n"
79			"  %s:%u: %s\n"
80			"  pid=%d tid=%d errno=%d - %s\n",
81			file, line, exp_str, getpid(), _gettid(),
82			errno, strerror(errno));
83		test_dump_stack();
84		if (fmt) {
85			fputs("  ", stderr);
86			vfprintf(stderr, fmt, ap);
87			fputs("\n", stderr);
88		}
89		va_end(ap);
90
91		if (errno == EACCES) {
92			print_skip("Access denied - Exiting");
93			exit(KSFT_SKIP);
94		}
95		exit(254);
96	}
97
98	return;
99}
100