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/*
* linux/arch/i386/kernel/i387.c
*
* Copyright (C) 1994 Linus Torvalds
*
* Pentium III FXSR, SSE support
* General FPU state handling cleanups
* Gareth Hughes <gareth@valinux.com>, May 2000
*/
#include <linux/config.h>
#include <linux/sched.h>
#include <asm/processor.h>
#include <asm/i387.h>
#include <asm/math_emu.h>
#include <asm/sigcontext.h>
#include <asm/user.h>
#include <asm/ptrace.h>
#include <asm/uaccess.h>
#ifdef CONFIG_MATH_EMULATION
#define HAVE_HWFP (boot_cpu_data.hard_math)
#else
#define HAVE_HWFP 1
#endif
/*
* The _current_ task is using the FPU for the first time
* so initialize it and set the mxcsr to its default
* value at reset if we support XMM instructions and then
* remeber the current task has used the FPU.
*/
void init_fpu(void)
{
__asm__("fninit");
if ( cpu_has_xmm )
load_mxcsr(0x1f80);
current->used_math = 1;
}
/*
* FPU lazy state save handling.
*/
static inline void __save_init_fpu( struct task_struct *tsk )
{
if ( cpu_has_fxsr ) {
asm volatile( "fxsave %0 ; fnclex"
: "=m" (tsk->thread.i387.fxsave) );
} else {
asm volatile( "fnsave %0 ; fwait"
: "=m" (tsk->thread.i387.fsave) );
}
tsk->flags &= ~PF_USEDFPU;
}
void save_init_fpu( struct task_struct *tsk )
{
__save_init_fpu(tsk);
stts();
}
void kernel_fpu_begin(void)
{
struct task_struct *tsk = current;
if (tsk->flags & PF_USEDFPU) {
__save_init_fpu(tsk);
return;
}
clts();
}
void restore_fpu( struct task_struct *tsk )
{
if ( cpu_has_fxsr ) {
asm volatile( "fxrstor %0"
: : "m" (tsk->thread.i387.fxsave) );
} else {
asm volatile( "frstor %0"
: : "m" (tsk->thread.i387.fsave) );
}
}
/*
* FPU tag word conversions.
*/
static inline unsigned short twd_i387_to_fxsr( unsigned short twd )
{
unsigned int tmp; /* to avoid 16 bit prefixes in the code */
/* Transform each pair of bits into 01 (valid) or 00 (empty) */
tmp = ~twd;
tmp = (tmp | (tmp>>1)) & 0x5555; /* 0V0V0V0V0V0V0V0V */
/* and move the valid bits to the lower byte. */
tmp = (tmp | (tmp >> 1)) & 0x3333; /* 00VV00VV00VV00VV */
tmp = (tmp | (tmp >> 2)) & 0x0f0f; /* 0000VVVV0000VVVV */
tmp = (tmp | (tmp >> 4)) & 0x00ff; /* 00000000VVVVVVVV */
return tmp;
}
static inline unsigned long twd_fxsr_to_i387( struct i387_fxsave_struct *fxsave )
{
struct _fpxreg *st = NULL;
unsigned long twd = (unsigned long) fxsave->twd;
unsigned long tag;
unsigned long ret = 0xffff0000;
int i;
#define FPREG_ADDR(f, n) ((char *)&(f)->st_space + (n) * 16);
for ( i = 0 ; i < 8 ; i++ ) {
if ( twd & 0x1 ) {
st = (struct _fpxreg *) FPREG_ADDR( fxsave, i );
switch ( st->exponent & 0x7fff ) {
case 0x7fff:
tag = 2; /* Special */
break;
case 0x0000:
if ( !st->significand[0] &&
!st->significand[1] &&
!st->significand[2] &&
!st->significand[3] ) {
tag = 1; /* Zero */
} else {
tag = 2; /* Special */
}
break;
default:
if ( st->significand[3] & 0x8000 ) {
tag = 0; /* Valid */
} else {
tag = 2; /* Special */
}
break;
}
} else {
tag = 3; /* Empty */
}
ret |= (tag << (2 * i));
twd = twd >> 1;
}
return ret;
}
/*
* FPU state interaction.
*/
unsigned short get_fpu_cwd( struct task_struct *tsk )
{
if ( cpu_has_fxsr ) {
return tsk->thread.i387.fxsave.cwd;
} else {
return (unsigned short)tsk->thread.i387.fsave.cwd;
}
}
unsigned short get_fpu_swd( struct task_struct *tsk )
{
if ( cpu_has_fxsr ) {
return tsk->thread.i387.fxsave.swd;
} else {
return (unsigned short)tsk->thread.i387.fsave.swd;
}
}
unsigned short get_fpu_twd( struct task_struct *tsk )
{
if ( cpu_has_fxsr ) {
return tsk->thread.i387.fxsave.twd;
} else {
return (unsigned short)tsk->thread.i387.fsave.twd;
}
}
unsigned short get_fpu_mxcsr( struct task_struct *tsk )
{
if ( cpu_has_xmm ) {
return tsk->thread.i387.fxsave.mxcsr;
} else {
return 0x1f80;
}
}
void set_fpu_cwd( struct task_struct *tsk, unsigned short cwd )
{
if ( cpu_has_fxsr ) {
tsk->thread.i387.fxsave.cwd = cwd;
} else {
tsk->thread.i387.fsave.cwd = ((long)cwd | 0xffff0000);
}
}
void set_fpu_swd( struct task_struct *tsk, unsigned short swd )
{
if ( cpu_has_fxsr ) {
tsk->thread.i387.fxsave.swd = swd;
} else {
tsk->thread.i387.fsave.swd = ((long)swd | 0xffff0000);
}
}
void set_fpu_twd( struct task_struct *tsk, unsigned short twd )
{
if ( cpu_has_fxsr ) {
tsk->thread.i387.fxsave.twd = twd_i387_to_fxsr(twd);
} else {
tsk->thread.i387.fsave.twd = ((long)twd | 0xffff0000);
}
}
void set_fpu_mxcsr( struct task_struct *tsk, unsigned short mxcsr )
{
if ( cpu_has_xmm ) {
tsk->thread.i387.fxsave.mxcsr = (mxcsr & 0xffbf);
}
}
/*
* FXSR floating point environment conversions.
*/
static inline int convert_fxsr_to_user( struct _fpstate *buf,
struct i387_fxsave_struct *fxsave )
{
unsigned long env[7];
struct _fpreg *to;
struct _fpxreg *from;
int i;
env[0] = (unsigned long)fxsave->cwd | 0xffff0000;
env[1] = (unsigned long)fxsave->swd | 0xffff0000;
env[2] = twd_fxsr_to_i387(fxsave);
env[3] = fxsave->fip;
env[4] = fxsave->fcs | ((unsigned long)fxsave->fop << 16);
env[5] = fxsave->foo;
env[6] = fxsave->fos;
if ( __copy_to_user( buf, env, 7 * sizeof(unsigned long) ) )
return 1;
to = &buf->_st[0];
from = (struct _fpxreg *) &fxsave->st_space[0];
for ( i = 0 ; i < 8 ; i++, to++, from++ ) {
if ( __copy_to_user( to, from, sizeof(*to) ) )
return 1;
}
return 0;
}
static inline int convert_fxsr_from_user( struct i387_fxsave_struct *fxsave,
struct _fpstate *buf )
{
unsigned long env[7];
struct _fpxreg *to;
struct _fpreg *from;
int i;
if ( __copy_from_user( env, buf, 7 * sizeof(long) ) )
return 1;
fxsave->cwd = (unsigned short)(env[0] & 0xffff);
fxsave->swd = (unsigned short)(env[1] & 0xffff);
fxsave->twd = twd_i387_to_fxsr((unsigned short)(env[2] & 0xffff));
fxsave->fip = env[3];
fxsave->fop = (unsigned short)((env[4] & 0xffff0000) >> 16);
fxsave->fcs = (env[4] & 0xffff);
fxsave->foo = env[5];
fxsave->fos = env[6];
to = (struct _fpxreg *) &fxsave->st_space[0];
from = &buf->_st[0];
for ( i = 0 ; i < 8 ; i++, to++, from++ ) {
if ( __copy_from_user( to, from, sizeof(*from) ) )
return 1;
}
return 0;
}
/*
* Signal frame handlers.
*/
static inline int save_i387_fsave( struct _fpstate *buf )
{
struct task_struct *tsk = current;
unlazy_fpu( tsk );
tsk->thread.i387.fsave.status = tsk->thread.i387.fsave.swd;
if ( __copy_to_user( buf, &tsk->thread.i387.fsave,
sizeof(struct i387_fsave_struct) ) )
return -1;
return 1;
}
static inline int save_i387_fxsave( struct _fpstate *buf )
{
struct task_struct *tsk = current;
int err = 0;
unlazy_fpu( tsk );
if ( convert_fxsr_to_user( buf, &tsk->thread.i387.fxsave ) )
return -1;
err |= __put_user( tsk->thread.i387.fxsave.swd, &buf->status );
err |= __put_user( X86_FXSR_MAGIC, &buf->magic );
if ( err )
return -1;
if ( __copy_to_user( &buf->_fxsr_env[0], &tsk->thread.i387.fxsave,
sizeof(struct i387_fxsave_struct) ) )
return -1;
return 1;
}
int save_i387( struct _fpstate *buf )
{
if ( !current->used_math )
return 0;
/* This will cause a "finit" to be triggered by the next
* attempted FPU operation by the 'current' process.
*/
current->used_math = 0;
if ( HAVE_HWFP ) {
if ( cpu_has_fxsr ) {
return save_i387_fxsave( buf );
} else {
return save_i387_fsave( buf );
}
} else {
return save_i387_soft( ¤t->thread.i387.soft, buf );
}
}
static inline int restore_i387_fsave( struct _fpstate *buf )
{
struct task_struct *tsk = current;
clear_fpu( tsk );
return __copy_from_user( &tsk->thread.i387.fsave, buf,
sizeof(struct i387_fsave_struct) );
}
static inline int restore_i387_fxsave( struct _fpstate *buf )
{
struct task_struct *tsk = current;
clear_fpu( tsk );
if ( __copy_from_user( &tsk->thread.i387.fxsave, &buf->_fxsr_env[0],
sizeof(struct i387_fxsave_struct) ) )
return 1;
/* mxcsr bit 6 and 31-16 must be zero for security reasons */
tsk->thread.i387.fxsave.mxcsr &= 0xffbf;
return convert_fxsr_from_user( &tsk->thread.i387.fxsave, buf );
}
int restore_i387( struct _fpstate *buf )
{
int err;
if ( HAVE_HWFP ) {
if ( cpu_has_fxsr ) {
err = restore_i387_fxsave( buf );
} else {
err = restore_i387_fsave( buf );
}
} else {
err = restore_i387_soft( ¤t->thread.i387.soft, buf );
}
current->used_math = 1;
return err;
}
/*
* ptrace request handlers.
*/
static inline int get_fpregs_fsave( struct user_i387_struct *buf,
struct task_struct *tsk )
{
return __copy_to_user( buf, &tsk->thread.i387.fsave,
sizeof(struct user_i387_struct) );
}
static inline int get_fpregs_fxsave( struct user_i387_struct *buf,
struct task_struct *tsk )
{
return convert_fxsr_to_user( (struct _fpstate *)buf,
&tsk->thread.i387.fxsave );
}
int get_fpregs( struct user_i387_struct *buf, struct task_struct *tsk )
{
if ( HAVE_HWFP ) {
if ( cpu_has_fxsr ) {
return get_fpregs_fxsave( buf, tsk );
} else {
return get_fpregs_fsave( buf, tsk );
}
} else {
return save_i387_soft( &tsk->thread.i387.soft,
(struct _fpstate *)buf );
}
}
static inline int set_fpregs_fsave( struct task_struct *tsk,
struct user_i387_struct *buf )
{
return __copy_from_user( &tsk->thread.i387.fsave, buf,
sizeof(struct user_i387_struct) );
}
static inline int set_fpregs_fxsave( struct task_struct *tsk,
struct user_i387_struct *buf )
{
return convert_fxsr_from_user( &tsk->thread.i387.fxsave,
(struct _fpstate *)buf );
}
int set_fpregs( struct task_struct *tsk, struct user_i387_struct *buf )
{
if ( HAVE_HWFP ) {
if ( cpu_has_fxsr ) {
return set_fpregs_fxsave( tsk, buf );
} else {
return set_fpregs_fsave( tsk, buf );
}
} else {
return restore_i387_soft( &tsk->thread.i387.soft,
(struct _fpstate *)buf );
}
}
int get_fpxregs( struct user_fxsr_struct *buf, struct task_struct *tsk )
{
if ( cpu_has_fxsr ) {
if (__copy_to_user( (void *)buf, &tsk->thread.i387.fxsave,
sizeof(struct user_fxsr_struct) ))
return -EFAULT;
return 0;
} else {
return -EIO;
}
}
int set_fpxregs( struct task_struct *tsk, struct user_fxsr_struct *buf )
{
if ( cpu_has_fxsr ) {
__copy_from_user( &tsk->thread.i387.fxsave, (void *)buf,
sizeof(struct user_fxsr_struct) );
/* mxcsr bit 6 and 31-16 must be zero for security reasons */
tsk->thread.i387.fxsave.mxcsr &= 0xffbf;
return 0;
} else {
return -EIO;
}
}
/*
* FPU state for core dumps.
*/
static inline void copy_fpu_fsave( struct task_struct *tsk,
struct user_i387_struct *fpu )
{
memcpy( fpu, &tsk->thread.i387.fsave,
sizeof(struct user_i387_struct) );
}
static inline void copy_fpu_fxsave( struct task_struct *tsk,
struct user_i387_struct *fpu )
{
unsigned short *to;
unsigned short *from;
int i;
memcpy( fpu, &tsk->thread.i387.fxsave, 7 * sizeof(long) );
to = (unsigned short *)&fpu->st_space[0];
from = (unsigned short *)&tsk->thread.i387.fxsave.st_space[0];
for ( i = 0 ; i < 8 ; i++, to += 5, from += 8 ) {
memcpy( to, from, 5 * sizeof(unsigned short) );
}
}
int dump_fpu( struct pt_regs *regs, struct user_i387_struct *fpu )
{
int fpvalid;
struct task_struct *tsk = current;
fpvalid = tsk->used_math;
if ( fpvalid ) {
unlazy_fpu( tsk );
if ( cpu_has_fxsr ) {
copy_fpu_fxsave( tsk, fpu );
} else {
copy_fpu_fsave( tsk, fpu );
}
}
return fpvalid;
}
int dump_extended_fpu( struct pt_regs *regs, struct user_fxsr_struct *fpu )
{
int fpvalid;
struct task_struct *tsk = current;
fpvalid = tsk->used_math && cpu_has_fxsr;
if ( fpvalid ) {
unlazy_fpu( tsk );
memcpy( fpu, &tsk->thread.i387.fxsave,
sizeof(struct user_fxsr_struct) );
}
return fpvalid;
}
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