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/arch/x86_64/ia32/fpu32.c

https://bitbucket.org/evzijst/gittest
C | 184 lines | 153 code | 20 blank | 11 comment | 22 complexity | 71770fd93aa917da6827412a5b68a470 MD5 | raw file
  1/* 
  2 * Copyright 2002 Andi Kleen, SuSE Labs.
  3 * FXSAVE<->i387 conversion support. Based on code by Gareth Hughes.
  4 * This is used for ptrace, signals and coredumps in 32bit emulation.
  5 * $Id: fpu32.c,v 1.1 2002/03/21 14:16:32 ak Exp $
  6 */ 
  7
  8#include <linux/sched.h>
  9#include <asm/sigcontext32.h>
 10#include <asm/processor.h>
 11#include <asm/uaccess.h>
 12#include <asm/i387.h>
 13
 14static inline unsigned short twd_i387_to_fxsr(unsigned short twd)
 15{
 16	unsigned int tmp; /* to avoid 16 bit prefixes in the code */
 17 
 18	/* Transform each pair of bits into 01 (valid) or 00 (empty) */
 19        tmp = ~twd;
 20        tmp = (tmp | (tmp>>1)) & 0x5555; /* 0V0V0V0V0V0V0V0V */
 21        /* and move the valid bits to the lower byte. */
 22        tmp = (tmp | (tmp >> 1)) & 0x3333; /* 00VV00VV00VV00VV */
 23        tmp = (tmp | (tmp >> 2)) & 0x0f0f; /* 0000VVVV0000VVVV */
 24        tmp = (tmp | (tmp >> 4)) & 0x00ff; /* 00000000VVVVVVVV */
 25        return tmp;
 26}
 27
 28static inline unsigned long twd_fxsr_to_i387(struct i387_fxsave_struct *fxsave)
 29{
 30	struct _fpxreg *st = NULL;
 31	unsigned long tos = (fxsave->swd >> 11) & 7;
 32	unsigned long twd = (unsigned long) fxsave->twd;
 33	unsigned long tag;
 34	unsigned long ret = 0xffff0000;
 35	int i;
 36
 37#define FPREG_ADDR(f, n)	((void *)&(f)->st_space + (n) * 16);
 38
 39	for (i = 0 ; i < 8 ; i++) {
 40		if (twd & 0x1) {
 41			st = FPREG_ADDR( fxsave, (i - tos) & 7 );
 42
 43			switch (st->exponent & 0x7fff) {
 44			case 0x7fff:
 45				tag = 2;		/* Special */
 46				break;
 47			case 0x0000:
 48				if ( !st->significand[0] &&
 49				     !st->significand[1] &&
 50				     !st->significand[2] &&
 51				     !st->significand[3] ) {
 52					tag = 1;	/* Zero */
 53				} else {
 54					tag = 2;	/* Special */
 55				}
 56				break;
 57			default:
 58				if (st->significand[3] & 0x8000) {
 59					tag = 0;	/* Valid */
 60				} else {
 61					tag = 2;	/* Special */
 62				}
 63				break;
 64			}
 65		} else {
 66			tag = 3;			/* Empty */
 67		}
 68		ret |= (tag << (2 * i));
 69		twd = twd >> 1;
 70	}
 71	return ret;
 72}
 73
 74
 75static inline int convert_fxsr_from_user(struct i387_fxsave_struct *fxsave,
 76					 struct _fpstate_ia32 __user *buf)
 77{
 78	struct _fpxreg *to;
 79	struct _fpreg __user *from;
 80	int i;
 81	u32 v;
 82	int err = 0;
 83
 84#define G(num,val) err |= __get_user(val, num + (u32 __user *)buf)
 85	G(0, fxsave->cwd);
 86	G(1, fxsave->swd);
 87	G(2, fxsave->twd);
 88	fxsave->twd = twd_i387_to_fxsr(fxsave->twd);
 89	G(3, fxsave->rip);
 90	G(4, v);
 91	fxsave->fop = v>>16;	/* cs ignored */
 92	G(5, fxsave->rdp);
 93	/* 6: ds ignored */
 94#undef G
 95	if (err) 
 96		return -1; 
 97
 98	to = (struct _fpxreg *)&fxsave->st_space[0];
 99	from = &buf->_st[0];
100	for (i = 0 ; i < 8 ; i++, to++, from++) {
101		if (__copy_from_user(to, from, sizeof(*from)))
102			return -1;
103	}
104	return 0;
105}
106
107
108static inline int convert_fxsr_to_user(struct _fpstate_ia32 __user *buf,
109				       struct i387_fxsave_struct *fxsave,
110				       struct pt_regs *regs,
111				       struct task_struct *tsk)
112{
113	struct _fpreg __user *to;
114	struct _fpxreg *from;
115	int i;
116	u16 cs,ds; 
117	int err = 0; 
118
119	if (tsk == current) {
120		/* should be actually ds/cs at fpu exception time,
121		   but that information is not available in 64bit mode. */
122		asm("movw %%ds,%0 " : "=r" (ds)); 
123		asm("movw %%cs,%0 " : "=r" (cs)); 		
124	} else { /* ptrace. task has stopped. */
125		ds = tsk->thread.ds;
126		cs = regs->cs;
127	} 
128
129#define P(num,val) err |= __put_user(val, num + (u32 __user *)buf)
130	P(0, (u32)fxsave->cwd | 0xffff0000);
131	P(1, (u32)fxsave->swd | 0xffff0000);
132	P(2, twd_fxsr_to_i387(fxsave));
133	P(3, (u32)fxsave->rip);
134	P(4,  cs | ((u32)fxsave->fop) << 16); 
135	P(5, fxsave->rdp);
136	P(6, 0xffff0000 | ds);
137#undef P
138
139	if (err) 
140		return -1; 
141
142	to = &buf->_st[0];
143	from = (struct _fpxreg *) &fxsave->st_space[0];
144	for ( i = 0 ; i < 8 ; i++, to++, from++ ) {
145		if (__copy_to_user(to, from, sizeof(*to)))
146			return -1;
147	}
148	return 0;
149}
150
151int restore_i387_ia32(struct task_struct *tsk, struct _fpstate_ia32 __user *buf, int fsave) 
152{ 
153	clear_fpu(tsk);
154	if (!fsave) { 
155		if (__copy_from_user(&tsk->thread.i387.fxsave, 
156				     &buf->_fxsr_env[0],
157				     sizeof(struct i387_fxsave_struct)))
158			return -1;
159		tsk->thread.i387.fxsave.mxcsr &= mxcsr_feature_mask;
160		set_stopped_child_used_math(tsk);
161	} 
162	return convert_fxsr_from_user(&tsk->thread.i387.fxsave, buf);
163}  
164
165int save_i387_ia32(struct task_struct *tsk, 
166		   struct _fpstate_ia32 __user *buf, 
167		   struct pt_regs *regs,
168		   int fsave)
169{
170	int err = 0;
171
172	init_fpu(tsk);
173	if (convert_fxsr_to_user(buf, &tsk->thread.i387.fxsave, regs, tsk))
174		return -1;
175	if (fsave)
176		return 0;
177	err |= __put_user(tsk->thread.i387.fxsave.swd, &buf->status);
178	if (fsave) 
179		return err ? -1 : 1; 	
180	err |= __put_user(X86_FXSR_MAGIC, &buf->magic);
181	err |= __copy_to_user(&buf->_fxsr_env[0], &tsk->thread.i387.fxsave,
182			      sizeof(struct i387_fxsave_struct));
183	return err ? -1 : 1;
184}