linux-kernel - [PATCH 2/5] kselftest/arm64: Check that unsupported regsets fail in sve-ptrace

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Message-Id: <20250820-arm64-sme-ptrace-sme-only-v1-2-f7c22b2871f8@kernel.org>
Date: Wed, 20 Aug 2025 19:29:04 +0100
From: Mark Brown <broonie@...nel.org>
To: Catalin Marinas <catalin.marinas@....com>, 
 Will Deacon <will@...nel.org>, Shuah Khan <shuah@...nel.org>, 
 Jonathan Corbet <corbet@....net>, Oleg Nesterov <oleg@...hat.com>
Cc: Mark Rutland <mark.rutland@....com>, 
 David Spickett <david.spickett@....com>, 
 Thiago Jung Bauermann <thiago.bauermann@...aro.org>, 
 Luis Machado <luis.machado.foss@...il.com>, 
 linux-arm-kernel@...ts.infradead.org, linux-kselftest@...r.kernel.org, 
 linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org, 
 Mark Brown <broonie@...nel.org>
Subject: [PATCH 2/5] kselftest/arm64: Check that unsupported regsets fail
 in sve-ptrace

Add a test which verifies that NT_ARM_SVE and NT_ARM_SSVE reads and writes
are rejected as expected when the relevant architecture feature is not
supported.

Signed-off-by: Mark Brown <broonie@...nel.org>
---
 tools/testing/selftests/arm64/fp/sve-ptrace.c | 46 +++++++++++++++++++++++++++
 1 file changed, 46 insertions(+)

diff --git a/tools/testing/selftests/arm64/fp/sve-ptrace.c b/tools/testing/selftests/arm64/fp/sve-ptrace.c
index a9b2377c46b8..5f39ca0b4194 100644
--- a/tools/testing/selftests/arm64/fp/sve-ptrace.c
+++ b/tools/testing/selftests/arm64/fp/sve-ptrace.c
@@ -158,6 +158,38 @@ static int set_sve(pid_t pid, const struct vec_type *type,
 	return ptrace(PTRACE_SETREGSET, pid, type->regset, &iov);
 }
 
+/* A read operation fails */
+static void read_fails(pid_t child, const struct vec_type *type)
+{
+	struct user_sve_header *new_sve = NULL;
+	size_t new_sve_size = 0;
+	void *ret;
+
+	ret = get_sve(child, type, (void **)&new_sve, &new_sve_size);
+
+	ksft_test_result(ret == NULL, "%s unsupported read fails\n",
+			 type->name);
+
+	free(new_sve);
+}
+
+/* A write operation fails */
+static void write_fails(pid_t child, const struct vec_type *type)
+{
+	struct user_sve_header sve;
+	int ret;
+
+	/* Just the header, no data */
+	memset(&sve, 0, sizeof(sve));
+	sve.size = sizeof(sve);
+	sve.flags = SVE_PT_REGS_SVE;
+	sve.vl = SVE_VL_MIN;
+	ret = set_sve(child, type, &sve);
+
+	ksft_test_result(ret != 0, "%s unsupported write fails\n",
+			 type->name);
+}
+
 /* Validate setting and getting the inherit flag */
 static void ptrace_set_get_inherit(pid_t child, const struct vec_type *type)
 {
@@ -702,6 +734,20 @@ static int do_parent(pid_t child)
 	}
 
 	for (i = 0; i < ARRAY_SIZE(vec_types); i++) {
+		/*
+		 * If the vector type isn't supported reads and writes
+		 * should fail.
+		 */
+		if (!(getauxval(vec_types[i].hwcap_type) & vec_types[i].hwcap)) {
+			read_fails(child, &vec_types[i]);
+			write_fails(child, &vec_types[i]);
+		} else {
+			ksft_test_result_skip("%s unsupported read fails\n",
+					      vec_types[i].name);
+			ksft_test_result_skip("%s unsupported write fails\n",
+					      vec_types[i].name);
+		}
+
 		/* FPSIMD via SVE regset */
 		if (getauxval(vec_types[i].hwcap_type) & vec_types[i].hwcap) {
 			ptrace_sve_fpsimd(child, &vec_types[i]);

-- 
2.39.5