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/*
* Copyright 2002 Andi Kleen, SuSE Labs.
* FXSAVE<->i387 conversion support. Based on code by Gareth Hughes.
* This is used for ptrace, signals and coredumps in 32bit emulation.
*/
#include <linux/sched.h>
#include <asm/sigcontext32.h>
#include <asm/processor.h>
#include <asm/uaccess.h>
#include <asm/i387.h>
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;
}
#define FPREG_ADDR(f, n) ((void *)&(f)->st_space + (n) * 16);
#define FP_EXP_TAG_VALID 0
#define FP_EXP_TAG_ZERO 1
#define FP_EXP_TAG_SPECIAL 2
#define FP_EXP_TAG_EMPTY 3
static inline unsigned long twd_fxsr_to_i387(struct i387_fxsave_struct *fxsave)
{
struct _fpxreg *st;
unsigned long tos = (fxsave->swd >> 11) & 7;
unsigned long twd = (unsigned long) fxsave->twd;
unsigned long tag;
unsigned long ret = 0xffff0000;
int i;
for (i = 0; i < 8; i++, twd >>= 1) {
if (twd & 0x1) {
st = FPREG_ADDR(fxsave, (i - tos) & 7);
switch (st->exponent & 0x7fff) {
case 0x7fff:
tag = FP_EXP_TAG_SPECIAL;
break;
case 0x0000:
if (!st->significand[0] &&
!st->significand[1] &&
!st->significand[2] &&
!st->significand[3])
tag = FP_EXP_TAG_ZERO;
else
tag = FP_EXP_TAG_SPECIAL;
break;
default:
if (st->significand[3] & 0x8000)
tag = FP_EXP_TAG_VALID;
else
tag = FP_EXP_TAG_SPECIAL;
break;
}
} else {
tag = FP_EXP_TAG_EMPTY;
}
ret |= tag << (2 * i);
}
return ret;
}
#define G(num, val) err |= __get_user(val, num + (u32 __user *)buf)
static inline int convert_fxsr_from_user(struct i387_fxsave_struct *fxsave,
struct _fpstate_ia32 __user *buf)
{
struct _fpxreg *to;
struct _fpreg __user *from;
int i, err = 0;
u32 v;
G(0, fxsave->cwd);
G(1, fxsave->swd);
G(2, fxsave->twd);
fxsave->twd = twd_i387_to_fxsr(fxsave->twd);
G(3, fxsave->rip);
G(4, v);
/* cs ignored */
fxsave->fop = v>>16;
G(5, fxsave->rdp);
/* 6: ds ignored */
if (err)
return -1;
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;
}
#define P(num, val) err |= __put_user(val, num + (u32 __user *)buf)
static inline int convert_fxsr_to_user(struct _fpstate_ia32 __user *buf,
struct i387_fxsave_struct *fxsave,
struct pt_regs *regs,
struct task_struct *tsk)
{
struct _fpreg __user *to;
struct _fpxreg *from;
int i, err = 0;
u16 cs, ds;
if (tsk == current) {
/*
* should be actually ds/cs at fpu exception time, but
* that information is not available in 64bit mode.
*/
asm("movw %%ds,%0 " : "=r" (ds));
asm("movw %%cs,%0 " : "=r" (cs));
} else {
/* ptrace. task has stopped. */
ds = tsk->thread.ds;
cs = regs->cs;
}
P(0, (u32)fxsave->cwd | 0xffff0000);
P(1, (u32)fxsave->swd | 0xffff0000);
P(2, twd_fxsr_to_i387(fxsave));
P(3, (u32)fxsave->rip);
P(4, cs | ((u32)fxsave->fop) << 16);
P(5, fxsave->rdp);
P(6, 0xffff0000 | ds);
if (err)
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;
}
int restore_i387_ia32(struct task_struct *tsk,
struct _fpstate_ia32 __user *buf, int fsave)
{
clear_fpu(tsk);
if (!fsave) {
if (__copy_from_user(&tsk->thread.i387.fxsave,
&buf->_fxsr_env[0],
sizeof(struct i387_fxsave_struct)))
return -1;
tsk->thread.i387.fxsave.mxcsr &= mxcsr_feature_mask;
set_stopped_child_used_math(tsk);
}
return convert_fxsr_from_user(&tsk->thread.i387.fxsave, buf);
}
int save_i387_ia32(struct task_struct *tsk, struct _fpstate_ia32 __user *buf,
struct pt_regs *regs, int fsave)
{
int err = 0;
init_fpu(tsk);
if (convert_fxsr_to_user(buf, &tsk->thread.i387.fxsave, regs, tsk))
return -1;
if (fsave)
return 0;
err |= __put_user(tsk->thread.i387.fxsave.swd, &buf->status);
err |= __put_user(X86_FXSR_MAGIC, &buf->magic);
err |= __copy_to_user(&buf->_fxsr_env[0], &tsk->thread.i387.fxsave,
sizeof(struct i387_fxsave_struct));
return err ? -1 : 1;
}
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