kselftest/arm64: Verify simultaneous SSVE and ZA context generation

Add a test that generates SSVE and ZA context in a single signal frame to
ensure that nothing is going wrong in that case for any reason.
Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20230117-arm64-test-ssve-za-v1-2-203c00150154@kernel.orgSigned-off-by: Catalin Marinas <catalin.marinas@arm.com>

tools/testing/selftests/arm64/signal/testcases/ssve_za_regs.c

+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2021 ARM Limited
+ *
+ * Verify that both the streaming SVE and ZA register context in
+ * signal frames is set up as expected when enabled simultaneously.
+ */
+
+#include <signal.h>
+#include <ucontext.h>
+#include <sys/prctl.h>
+
+#include "test_signals_utils.h"
+#include "testcases.h"
+
+static union {
+	ucontext_t uc;
+	char buf[1024 * 128];
+} context;
+static unsigned int vls[SVE_VQ_MAX];
+unsigned int nvls = 0;
+
+static bool sme_get_vls(struct tdescr *td)
+{
+	int vq, vl;
+
+	/*
+	 * Enumerate up to SVE_VQ_MAX vector lengths
+	 */
+	for (vq = SVE_VQ_MAX; vq > 0; --vq) {
+		vl = prctl(PR_SME_SET_VL, vq * 16);
+		if (vl == -1)
+			return false;
+
+		vl &= PR_SME_VL_LEN_MASK;
+
+		/* Skip missing VLs */
+		vq = sve_vq_from_vl(vl);
+
+		vls[nvls++] = vl;
+	}
+
+	/* We need at least one VL */
+	if (nvls < 1) {
+		fprintf(stderr, "Only %d VL supported\n", nvls);
+		return false;
+	}
+
+	return true;
+}
+
+static void setup_regs(void)
+{
+	/* smstart sm; real data is TODO */
+	asm volatile(".inst 0xd503437f" : : : );
+
+	/* smstart za; real data is TODO */
+	asm volatile(".inst 0xd503457f" : : : );
+}
+
+static char zeros[ZA_SIG_REGS_SIZE(SVE_VQ_MAX)];
+
+static int do_one_sme_vl(struct tdescr *td, siginfo_t *si, ucontext_t *uc,
+			 unsigned int vl)
+{
+	size_t offset;
+	struct _aarch64_ctx *head = GET_BUF_RESV_HEAD(context);
+	struct _aarch64_ctx *regs;
+	struct sve_context *ssve;
+	struct za_context *za;
+	int ret;
+
+	fprintf(stderr, "Testing VL %d\n", vl);
+
+	ret = prctl(PR_SME_SET_VL, vl);
+	if (ret != vl) {
+		fprintf(stderr, "Failed to set VL, got %d\n", ret);
+		return 1;
+	}
+
+	/*
+	 * Get a signal context which should have the SVE and ZA
+	 * frames in it.
+	 */
+	setup_regs();
+	if (!get_current_context(td, &context.uc, sizeof(context)))
+		return 1;
+
+	regs = get_header(head, SVE_MAGIC, GET_BUF_RESV_SIZE(context),
+			  &offset);
+	if (!regs) {
+		fprintf(stderr, "No SVE context\n");
+		return 1;
+	}
+
+	ssve = (struct sve_context *)regs;
+	if (ssve->vl != vl) {
+		fprintf(stderr, "Got SSVE VL %d, expected %d\n", ssve->vl, vl);
+		return 1;
+	}
+
+	if (!(ssve->flags & SVE_SIG_FLAG_SM)) {
+		fprintf(stderr, "SVE_SIG_FLAG_SM not set in SVE record\n");
+		return 1;
+	}
+
+	fprintf(stderr, "Got expected SSVE size %u and VL %d\n",
+		regs->size, ssve->vl);
+
+	regs = get_header(head, ZA_MAGIC, GET_BUF_RESV_SIZE(context),
+			  &offset);
+	if (!regs) {
+		fprintf(stderr, "No ZA context\n");
+		return 1;
+	}
+
+	za = (struct za_context *)regs;
+	if (za->vl != vl) {
+		fprintf(stderr, "Got ZA VL %d, expected %d\n", za->vl, vl);
+		return 1;
+	}
+
+	fprintf(stderr, "Got expected ZA size %u and VL %d\n",
+		regs->size, za->vl);
+
+	/* We didn't load any data into ZA so it should be all zeros */
+	if (memcmp(zeros, (char *)za + ZA_SIG_REGS_OFFSET,
+		   ZA_SIG_REGS_SIZE(sve_vq_from_vl(za->vl))) != 0) {
+		fprintf(stderr, "ZA data invalid\n");
+		return 1;
+	}
+
+	return 0;
+}
+
+static int sme_regs(struct tdescr *td, siginfo_t *si, ucontext_t *uc)
+{
+	int i;
+
+	for (i = 0; i < nvls; i++) {
+		if (do_one_sme_vl(td, si, uc, vls[i]))
+			return 1;
+	}
+
+	td->pass = 1;
+
+	return 0;
+}
+
+struct tdescr tde = {
+	.name = "Streaming SVE registers",
+	.descr = "Check that we get the right Streaming SVE registers reported",
+	/*
+	 * We shouldn't require FA64 but things like memset() used in the
+	 * helpers might use unsupported instructions so for now disable
+	 * the test unless we've got the full instruction set.
+	 */
+	.feats_required = FEAT_SME | FEAT_SME_FA64,
+	.timeout = 3,
+	.init = sme_get_vls,
+	.run = sme_regs,
+};