Commit 8831d718 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'x86_fpu_for_v5.12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 

Pull x86 FPU updates from Borislav Petkov:
 "x86 fpu usage optimization and cleanups:

   - make 64-bit kernel code which uses 387 insns request a x87 init
     (FNINIT) explicitly when using the FPU

   - misc cleanups"

* tag 'x86_fpu_for_v5.12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/fpu/xstate: Use sizeof() instead of a constant
  x86/fpu/64: Don't FNINIT in kernel_fpu_begin()
  x86/fpu: Make the EFI FPU calling convention explicit
parents d00c4ed0 0a74d61c

arch/x86/include/asm/efi.h

+20 −4
Original line number Diff line number Diff line
@@ -69,17 +69,33 @@ extern unsigned long efi_mixed_mode_stack_pa; 
		#f " called with too many arguments (" #p ">" #n ")");	\

})



static inline void efi_fpu_begin(void)

{

	/*

	 * The UEFI calling convention (UEFI spec 2.3.2 and 2.3.4) requires

	 * that FCW and MXCSR (64-bit) must be initialized prior to calling

	 * UEFI code.  (Oddly the spec does not require that the FPU stack

	 * be empty.)

	 */

	kernel_fpu_begin_mask(KFPU_387 | KFPU_MXCSR);

}



static inline void efi_fpu_end(void)

{

	kernel_fpu_end();

}



#ifdef CONFIG_X86_32

#define arch_efi_call_virt_setup()					\

({									\

	kernel_fpu_begin();						\

	efi_fpu_begin();						\

	firmware_restrict_branch_speculation_start();			\

})



#define arch_efi_call_virt_teardown()					\

({									\

	firmware_restrict_branch_speculation_end();			\

	kernel_fpu_end();						\

	efi_fpu_end();							\

})



#define arch_efi_call_virt(p, f, args...)	p->f(args)
@@ -98,7 +114,7 @@ extern asmlinkage u64 __efi_call(void *fp, ...); 
#define arch_efi_call_virt_setup()					\

({									\

	efi_sync_low_kernel_mappings();					\

	kernel_fpu_begin();						\

	efi_fpu_begin();						\

	firmware_restrict_branch_speculation_start();			\

	efi_enter_mm();							\

})
@@ -110,7 +126,7 @@ extern asmlinkage u64 __efi_call(void *fp, ...); 
({									\

	efi_leave_mm();							\

	firmware_restrict_branch_speculation_end();			\

	kernel_fpu_end();						\

	efi_fpu_end();							\

})



#ifdef CONFIG_KASAN

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

+12 −0
Original line number Diff line number Diff line
@@ -32,7 +32,19 @@ extern void fpregs_mark_activate(void); 
/* Code that is unaware of kernel_fpu_begin_mask() can use this */

static inline void kernel_fpu_begin(void)

{

#ifdef CONFIG_X86_64

	/*

	 * Any 64-bit code that uses 387 instructions must explicitly request

	 * KFPU_387.

	 */

	kernel_fpu_begin_mask(KFPU_MXCSR);

#else

	/*

	 * 32-bit kernel code may use 387 operations as well as SSE2, etc,

	 * as long as it checks that the CPU has the required capability.

	 */

	kernel_fpu_begin_mask(KFPU_387 | KFPU_MXCSR);

#endif

}



/*

arch/x86/kernel/fpu/xstate.c

+2 −2
Original line number Diff line number Diff line
@@ -167,14 +167,14 @@ void fpstate_sanitize_xstate(struct fpu *fpu) 
		fx->fop = 0;

		fx->rip = 0;

		fx->rdp = 0;

		memset(&fx->st_space[0], 0, 128);

		memset(fx->st_space, 0, sizeof(fx->st_space));

	}



	/*

	 * SSE is in init state

	 */

	if (!(xfeatures & XFEATURE_MASK_SSE))

		memset(&fx->xmm_space[0], 0, 256);

		memset(fx->xmm_space, 0, sizeof(fx->xmm_space));



	/*

	 * First two features are FPU and SSE, which above we handled

arch/x86/platform/efi/efi_64.c

+2 −2
Original line number Diff line number Diff line
@@ -834,7 +834,7 @@ efi_set_virtual_address_map(unsigned long memory_map_size, 
							 virtual_map);

	efi_enter_mm();



	kernel_fpu_begin();

	efi_fpu_begin();



	/* Disable interrupts around EFI calls: */

	local_irq_save(flags);
@@ -843,7 +843,7 @@ efi_set_virtual_address_map(unsigned long memory_map_size, 
			  descriptor_version, virtual_map);

	local_irq_restore(flags);



	kernel_fpu_end();

	efi_fpu_end();



	/* grab the virtually remapped EFI runtime services table pointer */

	efi.runtime = READ_ONCE(systab->runtime);