1 files changed, 124 insertions, 0 deletions
diff --git a/tools/testing/selftests/rseq/syscall_errors_test.c b/tools/testing/selftests/rseq/syscall_errors_test.c
new file mode 100644
index 000000000000..a5d9e1f8a2dc
--- /dev/null
+++ b/tools/testing/selftests/rseq/syscall_errors_test.c
@@ -0,0 +1,124 @@
+// SPDX-License-Identifier: MIT
+// SPDX-FileCopyrightText: 2024 Michael Jeanson <mjeanson@efficios.com>
+
+#ifndef _GNU_SOURCE
+#define _GNU_SOURCE
+#endif
+
+#include <assert.h>
+#include <stdint.h>
+#include <syscall.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "rseq.h"
+
+static int sys_rseq(void *rseq_abi, uint32_t rseq_len,
+		    int flags, uint32_t sig)
+{
+	return syscall(__NR_rseq, rseq_abi, rseq_len, flags, sig);
+}
+
+/*
+ * Check the value of errno on some expected failures of the rseq syscall.
+ */
+
+int main(void)
+{
+	struct rseq_abi *global_rseq = rseq_get_abi();
+	int ret;
+	int errno_copy;
+
+	if (!rseq_available()) {
+		fprintf(stderr, "rseq syscall unavailable");
+		goto error;
+	}
+
+	/* The current thread is NOT registered. */
+
+	/* EINVAL */
+	errno = 0;
+	ret = sys_rseq(global_rseq, 32, -1, RSEQ_SIG);
+	errno_copy = errno;
+	fprintf(stderr, "Registration with invalid flag fails with errno set to EINVAL (ret = %d, errno = %s)\n", ret, strerrorname_np(errno_copy));
+	if (ret == 0 || errno_copy != EINVAL)
+		goto error;
+
+	errno = 0;
+	ret = sys_rseq((char *) global_rseq + 1, 32, 0, RSEQ_SIG);
+	errno_copy = errno;
+	fprintf(stderr, "Registration with unaligned rseq_abi fails with errno set to EINVAL (ret = %d, errno = %s)\n", ret, strerrorname_np(errno_copy));
+	if (ret == 0 || errno_copy != EINVAL)
+		goto error;
+
+	errno = 0;
+	ret = sys_rseq(global_rseq, 31, 0, RSEQ_SIG);
+	errno_copy = errno;
+	fprintf(stderr, "Registration with invalid size fails with errno set to EINVAL (ret = %d, errno = %s)\n", ret, strerrorname_np(errno_copy));
+	if (ret == 0 || errno_copy != EINVAL)
+		goto error;
+
+
+#if defined(__LP64__) && (!defined(__s390__) && !defined(__s390x__))
+	/*
+	 * We haven't found a reliable way to find an invalid address when
+	 * running a 32bit userspace on a 64bit kernel, so only run this test
+	 * on 64bit builds for the moment.
+	 *
+	 * Also exclude architectures that select
+	 * CONFIG_ALTERNATE_USER_ADDRESS_SPACE where the kernel and userspace
+	 * have their own address space and this failure can't happen.
+	 */
+
+	/* EFAULT */
+	errno = 0;
+	ret = sys_rseq((void *) -4096UL, 32, 0, RSEQ_SIG);
+	errno_copy = errno;
+	fprintf(stderr, "Registration with invalid address fails with errno set to EFAULT (ret = %d, errno = %s)\n", ret, strerrorname_np(errno_copy));
+	if (ret == 0 || errno_copy != EFAULT)
+		goto error;
+#endif
+
+	errno = 0;
+	ret = sys_rseq(global_rseq, 32, 0, RSEQ_SIG);
+	errno_copy = errno;
+	fprintf(stderr, "Registration succeeds for the current thread (ret = %d, errno = %s)\n", ret, strerrorname_np(errno_copy));
+	if (ret != 0 && errno != 0)
+		goto error;
+
+	/* The current thread is registered. */
+
+	/* EBUSY */
+	errno = 0;
+	ret = sys_rseq(global_rseq, 32, 0, RSEQ_SIG);
+	errno_copy = errno;
+	fprintf(stderr, "Double registration fails with errno set to EBUSY (ret = %d, errno = %s)\n", ret, strerrorname_np(errno_copy));
+	if (ret == 0 || errno_copy != EBUSY)
+		goto error;
+
+	/* EPERM */
+	errno = 0;
+	ret = sys_rseq(global_rseq, 32, RSEQ_ABI_FLAG_UNREGISTER, RSEQ_SIG + 1);
+	errno_copy = errno;
+	fprintf(stderr, "Unregistration with wrong RSEQ_SIG fails with errno to EPERM (ret = %d, errno = %s)\n", ret, strerrorname_np(errno_copy));
+	if (ret == 0 || errno_copy != EPERM)
+		goto error;
+
+	errno = 0;
+	ret = sys_rseq(global_rseq, 32, RSEQ_ABI_FLAG_UNREGISTER, RSEQ_SIG);
+	errno_copy = errno;
+	fprintf(stderr, "Unregistration succeeds for the current thread (ret = %d, errno = %s)\n", ret, strerrorname_np(errno_copy));
+	if (ret != 0)
+		goto error;
+
+	errno = 0;
+	ret = sys_rseq(global_rseq, 32, RSEQ_ABI_FLAG_UNREGISTER, RSEQ_SIG);
+	errno_copy = errno;
+	fprintf(stderr, "Double unregistration fails with errno set to EINVAL (ret = %d, errno = %s)\n", ret, strerrorname_np(errno_copy));
+	if (ret == 0 || errno_copy != EINVAL)
+		goto error;
+
+	return 0;
+error:
+	return -1;
+}