x86/fpu: Dont restore PKRU in fpregs_restore_userspace()

Browse source

switch_to() and flush_thread() write the task's PKRU value eagerly so
the PKRU value of current is always valid in the hardware.

That means there is no point in restoring PKRU on exit to user or when
reactivating the task's FPU registers in the signal frame setup path.

This allows to remove all the xstate buffer updates with PKRU values once
the PKRU state is stored in thread struct while a task is scheduled out.

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/20210623121456.303919033@linutronix.de

...

This commit is contained in:

Thomas Gleixner 2021-06-23 14:02:17 +02:00 • committed by Borislav Petkov

parent 65e9521021

commit 2ebe81c6d8

3 changed files with 35 additions and 2 deletions

Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL

Download patch file Download diff file Expand all files Collapse all files

16

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

View file

19

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

View file

2

arch/x86/kernel/fpu/core.c

View file