x86/fpu/xstate: Define new functions for clearing fpregs and xstates

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Currently, fpu__clear() clears all fpregs and xstates.  Once XSAVES
supervisor states are introduced, supervisor settings (e.g. CET xstates)
must remain active for signals; It is necessary to have separate functions:

- Create fpu__clear_user_states(): clear only user settings for signals;
- Create fpu__clear_all(): clear both user and supervisor settings in
   flush_thread().

Also modify copy_init_fpstate_to_fpregs() to take a mask from above two
functions.

Remove obvious side-comment in fpu__clear(), while at it.

 [ bp: Make the second argument of fpu__clear() bool after requesting it
   a bunch of times during review.
  - Add a comment about copy_init_fpstate_to_fpregs() locking needs. ]

Co-developed-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Link: https://lkml.kernel.org/r/20200512145444.15483-6-yu-cheng.yu@intel.com

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This commit is contained in:

Fenghua Yu 2020-05-12 07:54:39 -07:00 • committed by Borislav Petkov

parent 71581eefd7

commit b860eb8dce

5 changed files with 41 additions and 23 deletions

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3

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

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53

arch/x86/kernel/fpu/core.c

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arch/x86/kernel/fpu/signal.c

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arch/x86/kernel/process.c

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arch/x86/kernel/signal.c

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