linux-kernel - [PATCH 1/5] kselftest/arm64: Verify that we reject out of bounds VLs in sve-ptrace

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Message-Id: <20250820-arm64-sme-ptrace-sme-only-v1-1-f7c22b2871f8@kernel.org>
Date: Wed, 20 Aug 2025 19:29:03 +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 1/5] kselftest/arm64: Verify that we reject out of bounds
 VLs in sve-ptrace

We do not currently have a test that asserts that we reject attempts to set
a vector length smaller than SVE_VL_MIN or larger than SVE_VL_MAX, add one
since that is our current behaviour.

Signed-off-by: Mark Brown <broonie@...nel.org>
---
 tools/testing/selftests/arm64/fp/sve-ptrace.c | 32 ++++++++++++++++++++++++++-
 1 file changed, 31 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/arm64/fp/sve-ptrace.c b/tools/testing/selftests/arm64/fp/sve-ptrace.c
index b22303778fb0..a9b2377c46b8 100644
--- a/tools/testing/selftests/arm64/fp/sve-ptrace.c
+++ b/tools/testing/selftests/arm64/fp/sve-ptrace.c
@@ -66,7 +66,7 @@ static const struct vec_type vec_types[] = {
 };
 
 #define VL_TESTS (((TEST_VQ_MAX - SVE_VQ_MIN) + 1) * 4)
-#define FLAG_TESTS 2
+#define FLAG_TESTS 4
 #define FPSIMD_TESTS 2
 
 #define EXPECTED_TESTS ((VL_TESTS + FLAG_TESTS + FPSIMD_TESTS) * ARRAY_SIZE(vec_types))
@@ -270,6 +270,25 @@ static void check_u32(unsigned int vl, const char *reg,
 	}
 }
 
+/* Set out of range VLs */
+static void ptrace_set_vl_ranges(pid_t child, const struct vec_type *type)
+{
+	struct user_sve_header sve;
+	int ret;
+
+	memset(&sve, 0, sizeof(sve));
+	sve.flags = SVE_PT_REGS_SVE;
+	sve.size = sizeof(sve);
+
+	ret = set_sve(child, type, &sve);
+	ksft_test_result(ret != 0, "%s Set invalid VL 0\n", type->name);
+
+	sve.vl = SVE_VL_MAX + SVE_VQ_BYTES;
+	ret = set_sve(child, type, &sve);
+	ksft_test_result(ret != 0, "%s Set invalid VL %d\n", type->name,
+			 SVE_VL_MAX + SVE_VQ_BYTES);
+}
+
 /* Access the FPSIMD registers via the SVE regset */
 static void ptrace_sve_fpsimd(pid_t child, const struct vec_type *type)
 {
@@ -703,6 +722,17 @@ static int do_parent(pid_t child)
 					      vec_types[i].name);
 		}
 
+		/* Setting out of bounds VLs should fail */
+		if (getauxval(vec_types[i].hwcap_type) & vec_types[i].hwcap) {
+			ptrace_set_vl_ranges(child, &vec_types[i]);
+		} else {
+			ksft_test_result_skip("%s Set invalid VL 0\n",
+					      vec_types[i].name);
+			ksft_test_result_skip("%s Set invalid VL %d\n",
+					      vec_types[i].name,
+					      SVE_VL_MAX + SVE_VQ_BYTES);
+		}
+
 		/* Step through every possible VQ */
 		for (vq = SVE_VQ_MIN; vq <= TEST_VQ_MAX; vq++) {
 			vl = sve_vl_from_vq(vq);

-- 
2.39.5