x86/fpu/xstate: Add XFD #NM handler

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If the XFD MSR has feature bits set then #NM will be raised when user space
attempts to use an instruction related to one of these features.

When the task has no permissions to use that feature, raise SIGILL, which
is the same behavior as #UD.

If the task has permissions, calculate the new buffer size for the extended
feature set and allocate a larger fpstate. In the unlikely case that
vzalloc() fails, SIGSEGV is raised.

The allocation function will be added in the next step. Provide a stub
which fails for now.

  [ tglx: Updated serialization ]

Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20211021225527.10184-18-chang.seok.bae@intel.com

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This commit is contained in:

Chang S. Bae 2021-10-21 15:55:21 -07:00 • committed by Borislav Petkov

parent 672365477a

commit 783e87b404

3 changed files with 87 additions and 0 deletions

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

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47

arch/x86/kernel/fpu/xstate.c

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38

arch/x86/kernel/traps.c

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