Commit 1361b83a authored by Linus Torvalds's avatar Linus Torvalds Committed by H. Peter Anvin
Browse files

i387: Split up <asm/i387.h> into exported and internal interfaces 



While various modules include <asm/i387.h> to get access to things we
actually *intend* for them to use, most of that header file was really
pretty low-level internal stuff that we really don't want to expose to
others.

So split the header file into two: the small exported interfaces remain
in <asm/i387.h>, while the internal definitions that are only used by
core architecture code are now in <asm/fpu-internal.h>.

The guiding principle for this was to expose functions that we export to
modules, and leave them in <asm/i387.h>, while stuff that is used by
task switching or was marked GPL-only is in <asm/fpu-internal.h>.

The fpu-internal.h file could be further split up too, especially since
arch/x86/kvm/ uses some of the remaining stuff for its module.  But that
kvm usage should probably be abstracted out a bit, and at least now the
internal FPU accessor functions are much more contained.  Even if it
isn't perhaps as contained as it _could_ be.

Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/alpine.LFD.2.02.1202211340330.5354@i5.linux-foundation.org


Signed-off-by: default avatarH. Peter Anvin <hpa@linux.intel.com>
parent 8546c008

arch/x86/ia32/ia32_signal.c

+1 −0
Original line number Diff line number Diff line
@@ -24,6 +24,7 @@ 
#include <asm/ucontext.h>

#include <asm/uaccess.h>

#include <asm/i387.h>

#include <asm/fpu-internal.h>

#include <asm/ptrace.h>

#include <asm/ia32_unistd.h>

#include <asm/user32.h>

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

0 → 100644
+520 −0
Original line number Diff line number Diff line 
/*

 * Copyright (C) 1994 Linus Torvalds

 *

 * Pentium III FXSR, SSE support

 * General FPU state handling cleanups

 *	Gareth Hughes <gareth@valinux.com>, May 2000

 * x86-64 work by Andi Kleen 2002

 */



#ifndef _FPU_INTERNAL_H

#define _FPU_INTERNAL_H



#include <linux/kernel_stat.h>

#include <linux/regset.h>

#include <linux/slab.h>

#include <asm/asm.h>

#include <asm/cpufeature.h>

#include <asm/processor.h>

#include <asm/sigcontext.h>

#include <asm/user.h>

#include <asm/uaccess.h>

#include <asm/xsave.h>



extern unsigned int sig_xstate_size;

extern void fpu_init(void);



DECLARE_PER_CPU(struct task_struct *, fpu_owner_task);



extern user_regset_active_fn fpregs_active, xfpregs_active;

extern user_regset_get_fn fpregs_get, xfpregs_get, fpregs_soft_get,

				xstateregs_get;

extern user_regset_set_fn fpregs_set, xfpregs_set, fpregs_soft_set,

				 xstateregs_set;





/*

 * xstateregs_active == fpregs_active. Please refer to the comment

 * at the definition of fpregs_active.

 */

#define xstateregs_active	fpregs_active



extern struct _fpx_sw_bytes fx_sw_reserved;

#ifdef CONFIG_IA32_EMULATION

extern unsigned int sig_xstate_ia32_size;

extern struct _fpx_sw_bytes fx_sw_reserved_ia32;

struct _fpstate_ia32;

struct _xstate_ia32;

extern int save_i387_xstate_ia32(void __user *buf);

extern int restore_i387_xstate_ia32(void __user *buf);

#endif



#ifdef CONFIG_MATH_EMULATION

extern void finit_soft_fpu(struct i387_soft_struct *soft);

#else

static inline void finit_soft_fpu(struct i387_soft_struct *soft) {}

#endif



#define X87_FSW_ES (1 << 7)	/* Exception Summary */



static __always_inline __pure bool use_xsaveopt(void)

{

	return static_cpu_has(X86_FEATURE_XSAVEOPT);

}



static __always_inline __pure bool use_xsave(void)

{

	return static_cpu_has(X86_FEATURE_XSAVE);

}



static __always_inline __pure bool use_fxsr(void)

{

        return static_cpu_has(X86_FEATURE_FXSR);

}



extern void __sanitize_i387_state(struct task_struct *);



static inline void sanitize_i387_state(struct task_struct *tsk)

{

	if (!use_xsaveopt())

		return;

	__sanitize_i387_state(tsk);

}



#ifdef CONFIG_X86_64

static inline int fxrstor_checking(struct i387_fxsave_struct *fx)

{

	int err;



	/* See comment in fxsave() below. */

#ifdef CONFIG_AS_FXSAVEQ

	asm volatile("1:  fxrstorq %[fx]\n\t"

		     "2:\n"

		     ".section .fixup,\"ax\"\n"

		     "3:  movl $-1,%[err]\n"

		     "    jmp  2b\n"

		     ".previous\n"

		     _ASM_EXTABLE(1b, 3b)

		     : [err] "=r" (err)

		     : [fx] "m" (*fx), "0" (0));

#else

	asm volatile("1:  rex64/fxrstor (%[fx])\n\t"

		     "2:\n"

		     ".section .fixup,\"ax\"\n"

		     "3:  movl $-1,%[err]\n"

		     "    jmp  2b\n"

		     ".previous\n"

		     _ASM_EXTABLE(1b, 3b)

		     : [err] "=r" (err)

		     : [fx] "R" (fx), "m" (*fx), "0" (0));

#endif

	return err;

}



static inline int fxsave_user(struct i387_fxsave_struct __user *fx)

{

	int err;



	/*

	 * Clear the bytes not touched by the fxsave and reserved

	 * for the SW usage.

	 */

	err = __clear_user(&fx->sw_reserved,

			   sizeof(struct _fpx_sw_bytes));

	if (unlikely(err))

		return -EFAULT;



	/* See comment in fxsave() below. */

#ifdef CONFIG_AS_FXSAVEQ

	asm volatile("1:  fxsaveq %[fx]\n\t"

		     "2:\n"

		     ".section .fixup,\"ax\"\n"

		     "3:  movl $-1,%[err]\n"

		     "    jmp  2b\n"

		     ".previous\n"

		     _ASM_EXTABLE(1b, 3b)

		     : [err] "=r" (err), [fx] "=m" (*fx)

		     : "0" (0));

#else

	asm volatile("1:  rex64/fxsave (%[fx])\n\t"

		     "2:\n"

		     ".section .fixup,\"ax\"\n"

		     "3:  movl $-1,%[err]\n"

		     "    jmp  2b\n"

		     ".previous\n"

		     _ASM_EXTABLE(1b, 3b)

		     : [err] "=r" (err), "=m" (*fx)

		     : [fx] "R" (fx), "0" (0));

#endif

	if (unlikely(err) &&

	    __clear_user(fx, sizeof(struct i387_fxsave_struct)))

		err = -EFAULT;

	/* No need to clear here because the caller clears USED_MATH */

	return err;

}



static inline void fpu_fxsave(struct fpu *fpu)

{

	/* Using "rex64; fxsave %0" is broken because, if the memory operand

	   uses any extended registers for addressing, a second REX prefix

	   will be generated (to the assembler, rex64 followed by semicolon

	   is a separate instruction), and hence the 64-bitness is lost. */



#ifdef CONFIG_AS_FXSAVEQ

	/* Using "fxsaveq %0" would be the ideal choice, but is only supported

	   starting with gas 2.16. */

	__asm__ __volatile__("fxsaveq %0"

			     : "=m" (fpu->state->fxsave));

#else

	/* Using, as a workaround, the properly prefixed form below isn't

	   accepted by any binutils version so far released, complaining that

	   the same type of prefix is used twice if an extended register is

	   needed for addressing (fix submitted to mainline 2005-11-21).

	asm volatile("rex64/fxsave %0"

		     : "=m" (fpu->state->fxsave));

	   This, however, we can work around by forcing the compiler to select

	   an addressing mode that doesn't require extended registers. */

	asm volatile("rex64/fxsave (%[fx])"

		     : "=m" (fpu->state->fxsave)

		     : [fx] "R" (&fpu->state->fxsave));

#endif

}



#else  /* CONFIG_X86_32 */



/* perform fxrstor iff the processor has extended states, otherwise frstor */

static inline int fxrstor_checking(struct i387_fxsave_struct *fx)

{

	/*

	 * The "nop" is needed to make the instructions the same

	 * length.

	 */

	alternative_input(

		"nop ; frstor %1",

		"fxrstor %1",

		X86_FEATURE_FXSR,

		"m" (*fx));



	return 0;

}



static inline void fpu_fxsave(struct fpu *fpu)

{

	asm volatile("fxsave %[fx]"

		     : [fx] "=m" (fpu->state->fxsave));

}



#endif	/* CONFIG_X86_64 */



/*

 * These must be called with preempt disabled. Returns

 * 'true' if the FPU state is still intact.

 */

static inline int fpu_save_init(struct fpu *fpu)

{

	if (use_xsave()) {

		fpu_xsave(fpu);



		/*

		 * xsave header may indicate the init state of the FP.

		 */

		if (!(fpu->state->xsave.xsave_hdr.xstate_bv & XSTATE_FP))

			return 1;

	} else if (use_fxsr()) {

		fpu_fxsave(fpu);

	} else {

		asm volatile("fnsave %[fx]; fwait"

			     : [fx] "=m" (fpu->state->fsave));

		return 0;

	}



	/*

	 * If exceptions are pending, we need to clear them so

	 * that we don't randomly get exceptions later.

	 *

	 * FIXME! Is this perhaps only true for the old-style

	 * irq13 case? Maybe we could leave the x87 state

	 * intact otherwise?

	 */

	if (unlikely(fpu->state->fxsave.swd & X87_FSW_ES)) {

		asm volatile("fnclex");

		return 0;

	}

	return 1;

}



static inline int __save_init_fpu(struct task_struct *tsk)

{

	return fpu_save_init(&tsk->thread.fpu);

}



static inline int fpu_fxrstor_checking(struct fpu *fpu)

{

	return fxrstor_checking(&fpu->state->fxsave);

}



static inline int fpu_restore_checking(struct fpu *fpu)

{

	if (use_xsave())

		return fpu_xrstor_checking(fpu);

	else

		return fpu_fxrstor_checking(fpu);

}



static inline int restore_fpu_checking(struct task_struct *tsk)

{

	/* AMD K7/K8 CPUs don't save/restore FDP/FIP/FOP unless an exception

	   is pending.  Clear the x87 state here by setting it to fixed

	   values. "m" is a random variable that should be in L1 */

	alternative_input(

		ASM_NOP8 ASM_NOP2,

		"emms\n\t"		/* clear stack tags */

		"fildl %P[addr]",	/* set F?P to defined value */

		X86_FEATURE_FXSAVE_LEAK,

		[addr] "m" (tsk->thread.fpu.has_fpu));



	return fpu_restore_checking(&tsk->thread.fpu);

}



/*

 * Software FPU state helpers. Careful: these need to

 * be preemption protection *and* they need to be

 * properly paired with the CR0.TS changes!

 */

static inline int __thread_has_fpu(struct task_struct *tsk)

{

	return tsk->thread.fpu.has_fpu;

}



/* Must be paired with an 'stts' after! */

static inline void __thread_clear_has_fpu(struct task_struct *tsk)

{

	tsk->thread.fpu.has_fpu = 0;

	percpu_write(fpu_owner_task, NULL);

}



/* Must be paired with a 'clts' before! */

static inline void __thread_set_has_fpu(struct task_struct *tsk)

{

	tsk->thread.fpu.has_fpu = 1;

	percpu_write(fpu_owner_task, tsk);

}



/*

 * Encapsulate the CR0.TS handling together with the

 * software flag.

 *

 * These generally need preemption protection to work,

 * do try to avoid using these on their own.

 */

static inline void __thread_fpu_end(struct task_struct *tsk)

{

	__thread_clear_has_fpu(tsk);

	stts();

}



static inline void __thread_fpu_begin(struct task_struct *tsk)

{

	clts();

	__thread_set_has_fpu(tsk);

}



/*

 * FPU state switching for scheduling.

 *

 * This is a two-stage process:

 *

 *  - switch_fpu_prepare() saves the old state and

 *    sets the new state of the CR0.TS bit. This is

 *    done within the context of the old process.

 *

 *  - switch_fpu_finish() restores the new state as

 *    necessary.

 */

typedef struct { int preload; } fpu_switch_t;



/*

 * FIXME! We could do a totally lazy restore, but we need to

 * add a per-cpu "this was the task that last touched the FPU

 * on this CPU" variable, and the task needs to have a "I last

 * touched the FPU on this CPU" and check them.

 *

 * We don't do that yet, so "fpu_lazy_restore()" always returns

 * false, but some day..

 */

static inline int fpu_lazy_restore(struct task_struct *new, unsigned int cpu)

{

	return new == percpu_read_stable(fpu_owner_task) &&

		cpu == new->thread.fpu.last_cpu;

}



static inline fpu_switch_t switch_fpu_prepare(struct task_struct *old, struct task_struct *new, int cpu)

{

	fpu_switch_t fpu;



	fpu.preload = tsk_used_math(new) && new->fpu_counter > 5;

	if (__thread_has_fpu(old)) {

		if (!__save_init_fpu(old))

			cpu = ~0;

		old->thread.fpu.last_cpu = cpu;

		old->thread.fpu.has_fpu = 0;	/* But leave fpu_owner_task! */



		/* Don't change CR0.TS if we just switch! */

		if (fpu.preload) {

			new->fpu_counter++;

			__thread_set_has_fpu(new);

			prefetch(new->thread.fpu.state);

		} else

			stts();

	} else {

		old->fpu_counter = 0;

		old->thread.fpu.last_cpu = ~0;

		if (fpu.preload) {

			new->fpu_counter++;

			if (fpu_lazy_restore(new, cpu))

				fpu.preload = 0;

			else

				prefetch(new->thread.fpu.state);

			__thread_fpu_begin(new);

		}

	}

	return fpu;

}



/*

 * By the time this gets called, we've already cleared CR0.TS and

 * given the process the FPU if we are going to preload the FPU

 * state - all we need to do is to conditionally restore the register

 * state itself.

 */

static inline void switch_fpu_finish(struct task_struct *new, fpu_switch_t fpu)

{

	if (fpu.preload) {

		if (unlikely(restore_fpu_checking(new)))

			__thread_fpu_end(new);

	}

}



/*

 * Signal frame handlers...

 */

extern int save_i387_xstate(void __user *buf);

extern int restore_i387_xstate(void __user *buf);



static inline void __clear_fpu(struct task_struct *tsk)

{

	if (__thread_has_fpu(tsk)) {

		/* Ignore delayed exceptions from user space */

		asm volatile("1: fwait\n"

			     "2:\n"

			     _ASM_EXTABLE(1b, 2b));

		__thread_fpu_end(tsk);

	}

}



/*

 * The actual user_fpu_begin/end() functions

 * need to be preemption-safe.

 *

 * NOTE! user_fpu_end() must be used only after you

 * have saved the FP state, and user_fpu_begin() must

 * be used only immediately before restoring it.

 * These functions do not do any save/restore on

 * their own.

 */

static inline void user_fpu_end(void)

{

	preempt_disable();

	__thread_fpu_end(current);

	preempt_enable();

}



static inline void user_fpu_begin(void)

{

	preempt_disable();

	if (!user_has_fpu())

		__thread_fpu_begin(current);

	preempt_enable();

}



/*

 * These disable preemption on their own and are safe

 */

static inline void save_init_fpu(struct task_struct *tsk)

{

	WARN_ON_ONCE(!__thread_has_fpu(tsk));

	preempt_disable();

	__save_init_fpu(tsk);

	__thread_fpu_end(tsk);

	preempt_enable();

}



static inline void clear_fpu(struct task_struct *tsk)

{

	preempt_disable();

	__clear_fpu(tsk);

	preempt_enable();

}



/*

 * i387 state interaction

 */

static inline unsigned short get_fpu_cwd(struct task_struct *tsk)

{

	if (cpu_has_fxsr) {

		return tsk->thread.fpu.state->fxsave.cwd;

	} else {

		return (unsigned short)tsk->thread.fpu.state->fsave.cwd;

	}

}



static inline unsigned short get_fpu_swd(struct task_struct *tsk)

{

	if (cpu_has_fxsr) {

		return tsk->thread.fpu.state->fxsave.swd;

	} else {

		return (unsigned short)tsk->thread.fpu.state->fsave.swd;

	}

}



static inline unsigned short get_fpu_mxcsr(struct task_struct *tsk)

{

	if (cpu_has_xmm) {

		return tsk->thread.fpu.state->fxsave.mxcsr;

	} else {

		return MXCSR_DEFAULT;

	}

}



static bool fpu_allocated(struct fpu *fpu)

{

	return fpu->state != NULL;

}



static inline int fpu_alloc(struct fpu *fpu)

{

	if (fpu_allocated(fpu))

		return 0;

	fpu->state = kmem_cache_alloc(task_xstate_cachep, GFP_KERNEL);

	if (!fpu->state)

		return -ENOMEM;

	WARN_ON((unsigned long)fpu->state & 15);

	return 0;

}



static inline void fpu_free(struct fpu *fpu)

{

	if (fpu->state) {

		kmem_cache_free(task_xstate_cachep, fpu->state);

		fpu->state = NULL;

	}

}



static inline void fpu_copy(struct fpu *dst, struct fpu *src)

{

	memcpy(dst->state, src->state, xstate_size);

}



extern void fpu_finit(struct fpu *fpu);



#endif

arch/x86/include/asm/i387.h

+6 −506

File changed.

Preview size limit exceeded, changes collapsed.

arch/x86/kernel/cpu/common.c

+1 −0
Original line number Diff line number Diff line
@@ -28,6 +28,7 @@ 
#include <asm/apic.h>

#include <asm/desc.h>

#include <asm/i387.h>

#include <asm/fpu-internal.h>

#include <asm/mtrr.h>

#include <linux/numa.h>

#include <asm/asm.h>

arch/x86/kernel/i387.c

+2 −1
Original line number Diff line number Diff line
@@ -16,6 +16,7 @@ 
#include <asm/uaccess.h>

#include <asm/ptrace.h>

#include <asm/i387.h>

#include <asm/fpu-internal.h>

#include <asm/user.h>



#ifdef CONFIG_X86_64
@@ -124,7 +125,7 @@ EXPORT_SYMBOL_GPL(xstate_size); 
unsigned int sig_xstate_ia32_size = sizeof(struct _fpstate_ia32);

static struct i387_fxsave_struct fx_scratch __cpuinitdata;



void __cpuinit mxcsr_feature_mask_init(void)

static void __cpuinit mxcsr_feature_mask_init(void)

{

	unsigned long mask = 0;

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