1 files changed, 56 insertions, 0 deletions
diff --git a/tools/testing/selftests/arm64/signal/sve_helpers.c b/tools/testing/selftests/arm64/signal/sve_helpers.c
new file mode 100644
index 000000000000..0acc121af306
--- /dev/null
+++ b/tools/testing/selftests/arm64/signal/sve_helpers.c
@@ -0,0 +1,56 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2024 ARM Limited
+ *
+ * Common helper functions for SVE and SME functionality.
+ */
+
+#include <stdbool.h>
+#include <kselftest.h>
+#include <asm/sigcontext.h>
+#include <sys/prctl.h>
+
+unsigned int vls[SVE_VQ_MAX];
+unsigned int nvls;
+
+int sve_fill_vls(bool use_sme, int min_vls)
+{
+	int vq, vl;
+	int pr_set_vl = use_sme ? PR_SME_SET_VL : PR_SVE_SET_VL;
+	int len_mask = use_sme ? PR_SME_VL_LEN_MASK : PR_SVE_VL_LEN_MASK;
+
+	/*
+	 * Enumerate up to SVE_VQ_MAX vector lengths
+	 */
+	for (vq = SVE_VQ_MAX; vq > 0; --vq) {
+		vl = prctl(pr_set_vl, vq * 16);
+		if (vl == -1)
+			return KSFT_FAIL;
+
+		vl &= len_mask;
+
+		/*
+		 * Unlike SVE, SME does not require the minimum vector length
+		 * to be implemented, or the VLs to be consecutive, so any call
+		 * to the prctl might return the single implemented VL, which
+		 * might be larger than 16. So to avoid this loop never
+		 * terminating,  bail out here when we find a higher VL than
+		 * we asked for.
+		 * See the ARM ARM, DDI 0487K.a, B1.4.2: I_QQRNR and I_NWYBP.
+		 */
+		if (vq < sve_vq_from_vl(vl))
+			break;
+
+		/* Skip missing VLs */
+		vq = sve_vq_from_vl(vl);
+
+		vls[nvls++] = vl;
+	}
+
+	if (nvls < min_vls) {
+		fprintf(stderr, "Only %d VL supported\n", nvls);
+		return KSFT_SKIP;
+	}
+
+	return KSFT_PASS;
+}