x86/fpu: Make copy_xstate_to_kernel() usable for [x]fpregs_get()

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When xsave with init state optimization is used then a component's state
in the task's xsave buffer can be stale when the corresponding feature bit
is not set.

fpregs_get() and xfpregs_get() invoke fpstate_sanitize_xstate() to update
the task's xsave buffer before retrieving the FX or FP state. That's just
duplicated code as copy_xstate_to_kernel() already handles this correctly.

Add a copy mode argument to the function which allows to restrict the state
copy to the FP and SSE features.

Also rename the function to copy_xstate_to_uabi_buf() so the name reflects
what it is doing.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210623121452.805327286@linutronix.de

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Thomas Gleixner 2021-06-23 14:01:42 +02:00 • committed by Borislav Petkov

parent da53f60bb8

commit eb6f51723f

3 changed files with 42 additions and 14 deletions

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12

arch/x86/include/asm/fpu/xstate.h

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2

arch/x86/kernel/fpu/regset.c

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42

arch/x86/kernel/fpu/xstate.c

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