diff options
| author | Mark Rutland <mark.rutland@arm.com> | 2025-05-08 14:26:29 +0100 |
|---|---|---|
| committer | Will Deacon <will@kernel.org> | 2025-05-08 15:29:09 +0100 |
| commit | 99560c9452bb9819334bdb9c6e9e27c0f45f8829 (patch) | |
| tree | 6701067203318be50d2489b7b50ec3e7611b8c2e | |
| parent | 6ef1d778ce56c5bde1ac0a1f85fd9710efde6724 (diff) | |
arm64/fpsimd: signal: Use SMSTOP behaviour in setup_return()
Historically the behaviour of setup_return() was nondeterministic,
depending on whether the task's FSIMD/SVE/SME state happened to be live.
We fixed most of that in commit:
929fa99b1215 ("arm64/fpsimd: signal: Always save+flush state early")
... but we didn't decide on how clearing PSTATE.SM should behave, and left a
TODO comment to that effect.
Use the new task_smstop_sm() helper to make this behave as if an SMSTOP
instruction was used to exit streaming mode. This would have been the
most common behaviour prior to the commit above.
Fixes: 40a8e87bb328 ("arm64/sme: Disable ZA and streaming mode when handling signals")
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Mark Brown <broonie@kernel.org>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20250508132644.1395904-10-mark.rutland@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
| -rw-r--r-- | arch/arm64/kernel/signal.c | 18 |
1 files changed, 2 insertions, 16 deletions
diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c index d42d83b45249..417140cd399b 100644 --- a/arch/arm64/kernel/signal.c +++ b/arch/arm64/kernel/signal.c @@ -1476,22 +1476,8 @@ static int setup_return(struct pt_regs *regs, struct ksignal *ksig, /* Signal handlers are invoked with ZA and streaming mode disabled */ if (system_supports_sme()) { - /* - * If we were in streaming mode the saved register - * state was SVE but we will exit SM and use the - * FPSIMD register state. - * - * TODO: decide if this should behave as SMSTOP (e.g. reset - * FPSR + FPMR), or whether this should only clear the scalable - * registers + ZA state. - */ - if (current->thread.svcr & SVCR_SM_MASK) { - memset(¤t->thread.uw.fpsimd_state, 0, - sizeof(current->thread.uw.fpsimd_state)); - current->thread.fp_type = FP_STATE_FPSIMD; - } - - current->thread.svcr &= ~(SVCR_ZA_MASK | SVCR_SM_MASK); + task_smstop_sm(current); + current->thread.svcr &= ~SVCR_ZA_MASK; write_sysreg_s(0, SYS_TPIDR2_EL0); } |