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/$PPID/exe -fpai {backtrace addresses} | \
25 	 *		cat -n 1>&2
26 	 *
27 	 * Note that the spacing is different and there's no newline.
28 	 */
29 	size_t i;
30 	size_t n = 20;
31 	void *stack[n];
32 	const char *addr2line = "addr2line -s -e /proc/$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 
64 static pid_t _gettid(void)
65 {
66 	return syscall(SYS_gettid);
67 }
68 
69 void __attribute__((noinline))
70 test_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