[PATCH 4/5] kselftst/arm64: Test NT_ARM_SVE FPSIMD format writes on non-SVE systems
From: Mark Brown <broonie@kernel.org>
Date: 2025-08-20 18:29:39
Also in:
linux-doc, linux-kselftest, lkml
Subsystem:
arm64 port (aarch64 architecture), kernel selftest framework, the rest · Maintainers:
Catalin Marinas, Will Deacon, Shuah Khan, Linus Torvalds
In order to allow exiting streaming mode on systems with SME but not SVE we allow writes of FPSIMD format data via NT_ARM_SVE even when SVE is not supported, add a test case that covers this to sve-ptrace. We do not support reads. Signed-off-by: Mark Brown <broonie@kernel.org> --- tools/testing/selftests/arm64/fp/sve-ptrace.c | 61 +++++++++++++++++++++++++++ 1 file changed, 61 insertions(+)
diff --git a/tools/testing/selftests/arm64/fp/sve-ptrace.c b/tools/testing/selftests/arm64/fp/sve-ptrace.c
index 5f39ca0b4194..fe43fb07ee6c 100644
--- a/tools/testing/selftests/arm64/fp/sve-ptrace.c
+++ b/tools/testing/selftests/arm64/fp/sve-ptrace.c@@ -378,6 +378,58 @@ static void ptrace_sve_fpsimd(pid_t child, const struct vec_type *type) free(svebuf); } +/* Write the FPSIMD registers via the SVE regset when SVE is not supported */ +static void ptrace_sve_fpsimd_no_sve(pid_t child) +{ + void *svebuf; + struct user_sve_header *sve; + struct user_fpsimd_state *fpsimd, new_fpsimd; + unsigned int i, j; + unsigned char *p; + int ret; + + svebuf = malloc(SVE_PT_SIZE(0, SVE_PT_REGS_FPSIMD)); + if (!svebuf) { + ksft_test_result_fail("Failed to allocate FPSIMD buffer\n"); + return; + } + + /* On a system without SVE the VL should be set to 0 */ + memset(svebuf, 0, SVE_PT_SIZE(0, SVE_PT_REGS_FPSIMD)); + sve = svebuf; + sve->flags = SVE_PT_REGS_FPSIMD; + sve->size = SVE_PT_SIZE(0, SVE_PT_REGS_FPSIMD); + sve->vl = 0; + + /* Try to set a known FPSIMD state via PT_REGS_SVE */ + fpsimd = (struct user_fpsimd_state *)((char *)sve + + SVE_PT_FPSIMD_OFFSET); + for (i = 0; i < 32; ++i) { + p = (unsigned char *)&fpsimd->vregs[i]; + + for (j = 0; j < sizeof(fpsimd->vregs[i]); ++j) + p[j] = j; + } + + ret = set_sve(child, &vec_types[0], sve); + ksft_test_result(ret == 0, "FPSIMD write via SVE\n"); + if (ret) { + ksft_test_result_skip("Verify FPSIMD write via SVE\n"); + goto out; + } + + /* Verify via the FPSIMD regset */ + if (get_fpsimd(child, &new_fpsimd)) { + ksft_test_result_skip("Verify FPSIMD write via SVE\n"); + goto out; + } + ksft_test_result(memcmp(fpsimd, &new_fpsimd, sizeof(*fpsimd)) == 0, + "Verify FPSIMD write via SVE\n"); + +out: + free(svebuf); +} + /* Validate attempting to set SVE data and read SVE data */ static void ptrace_set_sve_get_sve_data(pid_t child, const struct vec_type *type,
@@ -810,6 +862,15 @@ static int do_parent(pid_t child) } } + /* We support SVE writes of FPSMID format on SME only systems */ + if (!(getauxval(AT_HWCAP) & HWCAP_SVE) && + (getauxval(AT_HWCAP2) & HWCAP2_SME)) { + ptrace_sve_fpsimd_no_sve(child); + } else { + ksft_test_result_skip("FPSIMD write via SVE\n"); + ksft_test_result_skip("Verify FPSIMD write via SVE\n"); + } + ret = EXIT_SUCCESS; error:
--
2.39.5