6.15-stable review patch. If anyone has any objections, please let me know.
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From: Mark Rutland mark.rutland@arm.com
[ Upstream commit a90878f297d3dba906a6261deccb1bd4a791ba52 ]
An exec() is expected to reset all FPSIMD/SVE/SME state, and barring special handling of the vector lengths, the state is expected to reset to zero. This reset is handled in fpsimd_flush_thread(), which the core exec() code calls via flush_thread().
When support was added for FPMR, no logic was added to fpsimd_flush_thread() to reset the FPMR value, and thus it is erroneously inherited across an exec().
Add the missing reset of FPMR.
Fixes: 203f2b95a882 ("arm64/fpsimd: Support FEAT_FPMR") Signed-off-by: Mark Rutland mark.rutland@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/20250409164010.3480271-9-mark.rutland@arm.com Signed-off-by: Catalin Marinas catalin.marinas@arm.com Signed-off-by: Sasha Levin sashal@kernel.org --- arch/arm64/kernel/fpsimd.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c index 72ab9649c705b..7ae01f02e18b7 100644 --- a/arch/arm64/kernel/fpsimd.c +++ b/arch/arm64/kernel/fpsimd.c @@ -1663,6 +1663,9 @@ void fpsimd_flush_thread(void) current->thread.svcr = 0; }
+ if (system_supports_fpmr()) + current->thread.uw.fpmr = 0; + current->thread.fp_type = FP_STATE_FPSIMD;
put_cpu_fpsimd_context();