1 files changed, 89 insertions, 0 deletions
diff --git a/tools/testing/selftests/x86/syscall_numbering.c b/tools/testing/selftests/x86/syscall_numbering.c
new file mode 100644
index 000000000..d6b09cb1a
--- /dev/null
+++ b/tools/testing/selftests/x86/syscall_numbering.c
@@ -0,0 +1,89 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * syscall_arg_fault.c - tests faults 32-bit fast syscall stack args
+ * Copyright (c) 2018 Andrew Lutomirski
+ */
+
+#define _GNU_SOURCE
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <stdbool.h>
+#include <errno.h>
+#include <unistd.h>
+#include <syscall.h>
+
+static int nerrs;
+
+#define X32_BIT 0x40000000UL
+
+static void check_enosys(unsigned long nr, bool *ok)
+{
+	/* If this fails, a segfault is reasonably likely. */
+	fflush(stdout);
+
+	long ret = syscall(nr, 0, 0, 0, 0, 0, 0);
+	if (ret == 0) {
+		printf("[FAIL]\tsyscall %lu succeeded, but it should have failed\n", nr);
+		*ok = false;
+	} else if (errno != ENOSYS) {
+		printf("[FAIL]\tsyscall %lu had error code %d, but it should have reported ENOSYS\n", nr, errno);
+		*ok = false;
+	}
+}
+
+static void test_x32_without_x32_bit(void)
+{
+	bool ok = true;
+
+	/*
+	 * Syscalls 512-547 are "x32" syscalls.  They are intended to be
+	 * called with the x32 (0x40000000) bit set.  Calling them without
+	 * the x32 bit set is nonsense and should not work.
+	 */
+	printf("[RUN]\tChecking syscalls 512-547\n");
+	for (int i = 512; i <= 547; i++)
+		check_enosys(i, &ok);
+
+	/*
+	 * Check that a handful of 64-bit-only syscalls are rejected if the x32
+	 * bit is set.
+	 */
+	printf("[RUN]\tChecking some 64-bit syscalls in x32 range\n");
+	check_enosys(16 | X32_BIT, &ok);	/* ioctl */
+	check_enosys(19 | X32_BIT, &ok);	/* readv */
+	check_enosys(20 | X32_BIT, &ok);	/* writev */
+
+	/*
+	 * Check some syscalls with high bits set.
+	 */
+	printf("[RUN]\tChecking numbers above 2^32-1\n");
+	check_enosys((1UL << 32), &ok);
+	check_enosys(X32_BIT | (1UL << 32), &ok);
+
+	if (!ok)
+		nerrs++;
+	else
+		printf("[OK]\tThey all returned -ENOSYS\n");
+}
+
+int main()
+{
+	/*
+	 * Anyone diagnosing a failure will want to know whether the kernel
+	 * supports x32.  Tell them.
+	 */
+	printf("\tChecking for x32...");
+	fflush(stdout);
+	if (syscall(39 | X32_BIT, 0, 0, 0, 0, 0, 0) >= 0) {
+		printf(" supported\n");
+	} else if (errno == ENOSYS) {
+		printf(" not supported\n");
+	} else {
+		printf(" confused\n");
+	}
+
+	test_x32_without_x32_bit();
+
+	return nerrs ? 1 : 0;
+}