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. */
18 static void __attribute__((noinline)) test_dump_stack(void);
19 static void test_dump_stack(void)
20 {
21 	/*
22 	 * Build and run this command:
23 	 *
24 	 *	addr2line -s -e /proc/$PPID/exe -fpai {backtrace addresses} | \
25 	 *		grep -v test_dump_stack | cat -n 1>&2
26 	 *
27 	 * Note that the spacing is different and there's no newline.
28 	 */
29 	size_t i;
30 	size_t n = 20;
31 	void *stack[n];
32 	const char *addr2line = "addr2line -s -e /proc/$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;
40 
41 	n = backtrace(stack, n);
42 	c = &cmd[0];
43 	c += sprintf(c, "%s", addr2line);
44 	/*
45 	 * Skip the first 3 frames: backtrace, test_dump_stack, and
46 	 * test_assert. We hope that backtrace isn't inlined and the other two
47 	 * we've declared noinline.
48 	 */
49 	for (i = 2; i < n; i++)
50 		c += sprintf(c, " %lx", ((unsigned long) stack[i]) - 1);
51 	c += sprintf(c, "%s", pipeline);
52 #pragma GCC diagnostic push
53 #pragma GCC diagnostic ignored "-Wunused-result"
54 	system(cmd);
55 #pragma GCC diagnostic pop
56 }
57 
58 static pid_t gettid(void)
59 {
60 	return syscall(SYS_gettid);
61 }
62 
63 void __attribute__((noinline))
64 test_assert(bool exp, const char *exp_str,
65 	const char *file, unsigned int line, const char *fmt, ...)
66 {
67 	va_list ap;
68 
69 	if (!(exp)) {
70 		va_start(ap, fmt);
71 
72 		fprintf(stderr, "==== Test Assertion Failure ====\n"
73 			"  %s:%u: %s\n"
74 			"  pid=%d tid=%d - %s\n",
75 			file, line, exp_str, getpid(), gettid(),
76 			strerror(errno));
77 		test_dump_stack();
78 		if (fmt) {
79 			fputs("  ", stderr);
80 			vfprintf(stderr, fmt, ap);
81 			fputs("\n", stderr);
82 		}
83 		va_end(ap);
84 
85 		if (errno == EACCES)
86 			ksft_exit_skip("Access denied - Exiting.\n");
87 		exit(254);
88 	}
89 
90 	return;
91 }
92