arm64/ptrace: Ensure that SME is set up for target when writing SSVE state
commit 5d0a8d2f upstream. When we use NT_ARM_SSVE to either enable streaming mode or change the vector length for a process we do not currently do anything to ensure that there is storage allocated for the SME specific register state. If the task had not previously used SME or we changed the vector length then the task will not have had TIF_SME set or backing storage for ZA/ZT allocated, resulting in inconsistent register sizes when saving state and spurious traps which flush the newly set register state. We should set TIF_SME to disable traps and ensure that storage is allocated for ZA and ZT if it is not already allocated. This requires modifying sme_alloc() to make the flush of any existing register state optional so we don't disturb existing state for ZA and ZT. Fixes: e12310a0 ("arm64/sme: Implement ptrace support for streaming mode SVE registers") Reported-by:David Spickett <David.Spickett@arm.com> Signed-off-by:
Mark Brown <broonie@kernel.org> Cc: <stable@vger.kernel.org> # 5.19.x Link: https://lore.kernel.org/r/20230810-arm64-fix-ptrace-race-v1-1-a5361fad2bd6@kernel.org Signed-off-by:
Catalin Marinas <catalin.marinas@arm.com> Signed-off-by:
Mark Brown <broonie@kernel.org> Signed-off-by:
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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1be35f5c
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