arm64: fpsimd: Always set TIF_FOREIGN_FPSTATE on task state flush
This patch updates fpsimd_flush_task_state() to mirror the new semantics of fpsimd_flush_cpu_state() introduced by commit d8ad71fa ("arm64: fpsimd: Fix TIF_FOREIGN_FPSTATE after invalidating cpu regs"). Both functions now implicitly set TIF_FOREIGN_FPSTATE to indicate that the task's FPSIMD state is not loaded into the cpu. As a side-effect, fpsimd_flush_task_state() now sets TIF_FOREIGN_FPSTATE even for non-running tasks. In the case of non-running tasks this is not useful but also harmless, because the flag is live only while the corresponding task is running. This function is not called from fast paths, so special-casing this for the task == current case is not really worth it. Compiler barriers previously present in restore_sve_fpsimd_context() are pulled into fpsimd_flush_task_state() so that it can be safely called with preemption enabled if necessary. Explicit calls to set TIF_FOREIGN_FPSTATE that accompany fpsimd_flush_task_state() calls and are now redundant are removed as appropriate. fpsimd_flush_task_state() is used to get exclusive access to the representation of the task's state via task_struct, for the purpose of replacing the state. Thus, the call to this function should happen before manipulating fpsimd_state or sve_state etc. in task_struct. Anomalous cases are reordered appropriately in order to make the code more consistent, although there should be no functional difference since these cases are protected by local_bh_disable() anyway. Signed-off-by:Dave Martin <Dave.Martin@arm.com> Reviewed-by:
Alex Bennée <alex.bennee@linaro.org> Reviewed-by:
Julien Grall <julien.grall@arm.com> Tested-by:
zhang.lei <zhang.lei@jp.fujitsu.com> Signed-off-by:
Marc Zyngier <marc.zyngier@arm.com>
parent
fd3bc912
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