kselftest/arm64: Add GCS signal tests

Do some testing of the signal handling for GCS, checking that a GCS
frame has the expected information in it and that the expected signals
are delivered with invalid operations.

Reviewed-by: Thiago Jung Bauermann <thiago.bauermann@linaro.org>
Tested-by: Thiago Jung Bauermann <thiago.bauermann@linaro.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20241001-arm64-gcs-v13-37-222b78d87eee@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

1 files changed, 62 insertions, 0 deletions

diff --git a/tools/testing/selftests/arm64/signal/testcases/gcs_exception_fault.c b/tools/testing/selftests/arm64/signal/testcases/gcs_exception_fault.c
new file mode 100644
index 000000000000..6228448b2ae7
--- /dev/null
+++ b/tools/testing/selftests/arm64/signal/testcases/gcs_exception_fault.c
@@ -0,0 +1,62 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2023 ARM Limited
+ */
+
+#include <errno.h>
+#include <signal.h>
+#include <unistd.h>
+
+#include <sys/mman.h>
+#include <sys/prctl.h>
+
+#include "test_signals_utils.h"
+#include "testcases.h"
+
+/*
+ * We should get this from asm/siginfo.h but the testsuite is being
+ * clever with redefining siginfo_t.
+ */
+#ifndef SEGV_CPERR
+#define SEGV_CPERR 10
+#endif
+
+static inline void gcsss1(uint64_t Xt)
+{
+	asm volatile (
+		"sys #3, C7, C7, #2, %0\n"
+		:
+		: "rZ" (Xt)
+		: "memory");
+}
+
+static int gcs_op_fault_trigger(struct tdescr *td)
+{
+	/*
+	 * The slot below our current GCS should be in a valid GCS but
+	 * must not have a valid cap in it.
+	 */
+	gcsss1(get_gcspr_el0() - 8);
+
+	return 0;
+}
+
+static int gcs_op_fault_signal(struct tdescr *td, siginfo_t *si,
+				  ucontext_t *uc)
+{
+	ASSERT_GOOD_CONTEXT(uc);
+
+	return 1;
+}
+
+struct tdescr tde = {
+	.name = "Invalid GCS operation",
+	.descr = "An invalid GCS operation generates the expected signal",
+	.feats_required = FEAT_GCS,
+	.timeout = 3,
+	.sig_ok = SIGSEGV,
+	.sig_ok_code = SEGV_CPERR,
+	.sanity_disabled = true,
+	.trigger = gcs_op_fault_trigger,
+	.run = gcs_op_fault_signal,
+};