Commit 23686ef2 authored by Thomas Gleixner's avatar Thomas Gleixner Committed by Borislav Petkov
Browse files

x86/fpu: Add basic helpers for dynamically enabled features 



To allow building up the infrastructure required to support dynamically
enabled FPU features, add:

 - XFEATURES_MASK_DYNAMIC

   This constant will hold xfeatures which can be dynamically enabled.

 - fpu_state_size_dynamic()

   A static branch for 64-bit and a simple 'return false' for 32-bit.

   This helper allows to add dynamic-feature-specific changes to common
   code which is shared between 32-bit and 64-bit without #ifdeffery.

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarChang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20211021225527.10184-8-chang.seok.bae@intel.com
parent db8268df

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

+21 −0
Original line number Diff line number Diff line
@@ -43,6 +43,9 @@ 
#define XFEATURE_MASK_USER_RESTORE	\

	(XFEATURE_MASK_USER_SUPPORTED & ~XFEATURE_MASK_PKRU)



/* Features which are dynamically enabled for a process on request */

#define XFEATURE_MASK_USER_DYNAMIC	0ULL



/* All currently supported supervisor features */

#define XFEATURE_MASK_SUPERVISOR_SUPPORTED (XFEATURE_MASK_PASID)
@@ -96,4 +99,22 @@ int xfeature_size(int xfeature_nr); 
void xsaves(struct xregs_state *xsave, u64 mask);

void xrstors(struct xregs_state *xsave, u64 mask);



#ifdef CONFIG_X86_64

DECLARE_STATIC_KEY_FALSE(__fpu_state_size_dynamic);

#endif



#ifdef CONFIG_X86_64

DECLARE_STATIC_KEY_FALSE(__fpu_state_size_dynamic);



static __always_inline __pure bool fpu_state_size_dynamic(void)

{

	return static_branch_unlikely(&__fpu_state_size_dynamic);

}

#else

static __always_inline __pure bool fpu_state_size_dynamic(void)

{

	return false;

}

#endif



#endif

arch/x86/kernel/fpu/core.c

+4 −0
Original line number Diff line number Diff line
@@ -25,6 +25,10 @@ 
#define CREATE_TRACE_POINTS

#include <asm/trace/fpu.h>



#ifdef CONFIG_X86_64

DEFINE_STATIC_KEY_FALSE(__fpu_state_size_dynamic);

#endif



/* The FPU state configuration data for kernel and user space */

struct fpu_state_config	fpu_kernel_cfg __ro_after_init;

struct fpu_state_config fpu_user_cfg __ro_after_init;