1 files changed, 87 insertions, 0 deletions
diff --git a/tools/testing/selftests/kvm/lib/assert.c b/tools/testing/selftests/kvm/lib/assert.c
new file mode 100644
index 000000000000..c9f5b7d4ce38
--- /dev/null
+++ b/tools/testing/selftests/kvm/lib/assert.c
@@ -0,0 +1,87 @@
+/*
+ * tools/testing/selftests/kvm/lib/assert.c
+ *
+ * Copyright (C) 2018, Google LLC.
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.
+ */
+
+#define _GNU_SOURCE /* for getline(3) and strchrnul(3)*/
+
+#include "test_util.h"
+
+#include <execinfo.h>
+#include <sys/syscall.h>
+
+/* Dumps the current stack trace to stderr. */
+static void __attribute__((noinline)) test_dump_stack(void);
+static void test_dump_stack(void)
+{
+	/*
+	 * Build and run this command:
+	 *
+	 *	addr2line -s -e /proc/$PPID/exe -fpai {backtrace addresses} | \
+	 *		grep -v test_dump_stack | cat -n 1>&2
+	 *
+	 * Note that the spacing is different and there's no newline.
+	 */
+	size_t i;
+	size_t n = 20;
+	void *stack[n];
+	const char *addr2line = "addr2line -s -e /proc/$PPID/exe -fpai";
+	const char *pipeline = "|cat -n 1>&2";
+	char cmd[strlen(addr2line) + strlen(pipeline) +
+		 /* N bytes per addr * 2 digits per byte + 1 space per addr: */
+		 n * (((sizeof(void *)) * 2) + 1) +
+		 /* Null terminator: */
+		 1];
+	char *c;
+
+	n = backtrace(stack, n);
+	c = &cmd[0];
+	c += sprintf(c, "%s", addr2line);
+	/*
+	 * Skip the first 3 frames: backtrace, test_dump_stack, and
+	 * test_assert. We hope that backtrace isn't inlined and the other two
+	 * we've declared noinline.
+	 */
+	for (i = 2; i < n; i++)
+		c += sprintf(c, " %lx", ((unsigned long) stack[i]) - 1);
+	c += sprintf(c, "%s", pipeline);
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wunused-result"
+	system(cmd);
+#pragma GCC diagnostic pop
+}
+
+static pid_t gettid(void)
+{
+	return syscall(SYS_gettid);
+}
+
+void __attribute__((noinline))
+test_assert(bool exp, const char *exp_str,
+	const char *file, unsigned int line, const char *fmt, ...)
+{
+	va_list ap;
+
+	if (!(exp)) {
+		va_start(ap, fmt);
+
+		fprintf(stderr, "==== Test Assertion Failure ====\n"
+			"  %s:%u: %s\n"
+			"  pid=%d tid=%d\n",
+			file, line, exp_str, getpid(), gettid());
+		test_dump_stack();
+		if (fmt) {
+			fputs("  ", stderr);
+			vfprintf(stderr, fmt, ap);
+			fputs("\n", stderr);
+		}
+		va_end(ap);
+
+		exit(254);
+	}
+
+	return;
+}