diff options
| author | Mark Rutland <mark.rutland@arm.com> | 2025-05-08 14:26:38 +0100 |
|---|---|---|
| committer | Will Deacon <will@kernel.org> | 2025-05-08 15:29:11 +0100 |
| commit | f916dd32a943a7ab40497718aa7bcf3648d2bb39 (patch) | |
| tree | b814667f357fa044930c1d3ee2e588595a397487 | |
| parent | b93e685ecff77e0b231c12802fb632ef36a62140 (diff) | |
arm64/fpsimd: ptrace: Mandate SVE payload for streaming-mode state
When a task has PSTATE.SM==1, reads of NT_ARM_SSVE are required to
always present a header with SVE_PT_REGS_SVE, and register data in SVE
format. Reads of NT_ARM_SSVE must never present register data in FPSIMD
format. Within the kernel, we always expect streaming SVE data to be
stored in SVE format.
Currently a user can write to NT_ARM_SSVE with a header presenting
SVE_PT_REGS_FPSIMD rather than SVE_PT_REGS_SVE, placing the task's
FPSIMD/SVE data into an invalid state.
To fix this we can either:
(a) Forbid such writes.
(b) Accept such writes, and immediately convert data into SVE format.
Take the simple option and forbid such writes.
Fixes: e12310a0d30f ("arm64/sme: Implement ptrace support for streaming mode SVE registers")
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David Spickett <david.spickett@arm.com>
Cc: Luis Machado <luis.machado@arm.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Mark Brown <broonie@kernel.org>
Cc: Will Deacon <will@kernel.org>
Reviewed-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20250508132644.1395904-19-mark.rutland@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
| -rw-r--r-- | arch/arm64/kernel/ptrace.c | 12 |
1 files changed, 11 insertions, 1 deletions
diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c index a2075e1df27c..cff72b420eab 100644 --- a/arch/arm64/kernel/ptrace.c +++ b/arch/arm64/kernel/ptrace.c @@ -890,6 +890,7 @@ static int sve_set_common(struct task_struct *target, struct user_sve_header header; unsigned int vq; unsigned long start, end; + bool fpsimd; /* Header */ if (count < sizeof(header)) @@ -900,6 +901,15 @@ static int sve_set_common(struct task_struct *target, goto out; /* + * Streaming SVE data is always stored and presented in SVE format. + * Require the user to provide SVE formatted data for consistency, and + * to avoid the risk that we configure the task into an invalid state. + */ + fpsimd = (header.flags & SVE_PT_REGS_MASK) == SVE_PT_REGS_FPSIMD; + if (fpsimd && type == ARM64_VEC_SME) + return -EINVAL; + + /* * Apart from SVE_PT_REGS_MASK, all SVE_PT_* flags are consumed by * vec_set_vector_length(), which will also validate them for us: */ @@ -945,7 +955,7 @@ static int sve_set_common(struct task_struct *target, /* Registers: FPSIMD-only case */ BUILD_BUG_ON(SVE_PT_FPSIMD_OFFSET != sizeof(header)); - if ((header.flags & SVE_PT_REGS_MASK) == SVE_PT_REGS_FPSIMD) { + if (fpsimd) { clear_tsk_thread_flag(target, TIF_SVE); target->thread.fp_type = FP_STATE_FPSIMD; ret = __fpr_set(target, regset, pos, count, kbuf, ubuf, |