[net-next-2.6.git] / arch / i386 / math-emu / get_address.c

/*---------------------------------------------------------------------------+
 |  get_address.c                                                            |
 |                                                                           |
 | Get the effective address from an FPU instruction.                        |
 |                                                                           |
 | Copyright (C) 1992,1993,1994,1997                                         |
 |                       W. Metzenthen, 22 Parker St, Ormond, Vic 3163,      |
 |                       Australia.  E-mail   billm@suburbia.net             |
 |                                                                           |
 |                                                                           |
 +---------------------------------------------------------------------------*/

/*---------------------------------------------------------------------------+
 | Note:                                                                     |
 |    The file contains code which accesses user memory.                     |
 |    Emulator static data may change when user memory is accessed, due to   |
 |    other processes using the emulator while swapping is in progress.      |
 +---------------------------------------------------------------------------*/


#include <linux/stddef.h>

#include <asm/uaccess.h>
#include <asm/desc.h>

#include "fpu_system.h"
#include "exception.h"
#include "fpu_emu.h"


#define FPU_WRITE_BIT 0x10

static int reg_offset[] = {
	offsetof(struct info,___eax),
	offsetof(struct info,___ecx),
	offsetof(struct info,___edx),
	offsetof(struct info,___ebx),
	offsetof(struct info,___esp),
	offsetof(struct info,___ebp),
	offsetof(struct info,___esi),
	offsetof(struct info,___edi)
};

#define REG_(x) (*(long *)(reg_offset[(x)]+(u_char *) FPU_info))

static int reg_offset_vm86[] = {
	offsetof(struct info,___cs),
	offsetof(struct info,___vm86_ds),
	offsetof(struct info,___vm86_es),
	offsetof(struct info,___vm86_fs),
	offsetof(struct info,___vm86_gs),
	offsetof(struct info,___ss),
	offsetof(struct info,___vm86_ds)
      };

#define VM86_REG_(x) (*(unsigned short *) \
		      (reg_offset_vm86[((unsigned)x)]+(u_char *) FPU_info))

/* These are dummy, fs and gs are not saved on the stack. */
#define ___FS ___ds
#define ___GS ___ds

static int reg_offset_pm[] = {
	offsetof(struct info,___cs),
	offsetof(struct info,___ds),
	offsetof(struct info,___es),
	offsetof(struct info,___FS),
	offsetof(struct info,___GS),
	offsetof(struct info,___ss),
	offsetof(struct info,___ds)
      };

#define PM_REG_(x) (*(unsigned short *) \
		      (reg_offset_pm[((unsigned)x)]+(u_char *) FPU_info))


/* Decode the SIB byte. This function assumes mod != 0 */
static int sib(int mod, unsigned long *fpu_eip)
{
  u_char ss,index,base;
  long offset;

  RE_ENTRANT_CHECK_OFF;
  FPU_code_access_ok(1);
  FPU_get_user(base, (u_char __user *) (*fpu_eip));   /* The SIB byte */
  RE_ENTRANT_CHECK_ON;
  (*fpu_eip)++;
  ss = base >> 6;
  index = (base >> 3) & 7;
  base &= 7;

  if ((mod == 0) && (base == 5))
    offset = 0;              /* No base register */
  else
    offset = REG_(base);

  if (index == 4)
    {
      /* No index register */
      /* A non-zero ss is illegal */
      if ( ss )
	EXCEPTION(EX_Invalid);
    }
  else
    {
      offset += (REG_(index)) << ss;
    }

  if (mod == 1)
    {
      /* 8 bit signed displacement */
      long displacement;
      RE_ENTRANT_CHECK_OFF;
      FPU_code_access_ok(1);
      FPU_get_user(displacement, (signed char __user *) (*fpu_eip));
      offset += displacement;
      RE_ENTRANT_CHECK_ON;
      (*fpu_eip)++;
    }
  else if (mod == 2 || base == 5) /* The second condition also has mod==0 */
    {
      /* 32 bit displacement */
      long displacement;
      RE_ENTRANT_CHECK_OFF;
      FPU_code_access_ok(4);
      FPU_get_user(displacement, (long __user *) (*fpu_eip));
      offset += displacement;
      RE_ENTRANT_CHECK_ON;
      (*fpu_eip) += 4;
    }

  return offset;
}


static unsigned long vm86_segment(u_char segment,
				  struct address *addr)
{
  segment--;
#ifdef PARANOID
  if ( segment > PREFIX_SS_ )
    {
      EXCEPTION(EX_INTERNAL|0x130);
      math_abort(FPU_info,SIGSEGV);
    }
#endif /* PARANOID */
  addr->selector = VM86_REG_(segment);
  return (unsigned long)VM86_REG_(segment) << 4;
}


/* This should work for 16 and 32 bit protected mode. */
static long pm_address(u_char FPU_modrm, u_char segment,
		       struct address *addr, long offset)
{ 
  struct desc_struct descriptor;
  unsigned long base_address, limit, address, seg_top;

  segment--;

#ifdef PARANOID
  /* segment is unsigned, so this also detects if segment was 0: */
  if ( segment > PREFIX_SS_ )
    {
      EXCEPTION(EX_INTERNAL|0x132);
      math_abort(FPU_info,SIGSEGV);
    }
#endif /* PARANOID */

  switch ( segment )
    {
      /* fs and gs aren't used by the kernel, so they still have their
	 user-space values. */
    case PREFIX_FS_-1:
      /* N.B. - movl %seg, mem is a 2 byte write regardless of prefix */
      savesegment(fs, addr->selector);
      break;
    case PREFIX_GS_-1:
      savesegment(gs, addr->selector);
      break;
    default:
      addr->selector = PM_REG_(segment);
    }

  descriptor = LDT_DESCRIPTOR(PM_REG_(segment));
  base_address = SEG_BASE_ADDR(descriptor);
  address = base_address + offset;
  limit = base_address
	+ (SEG_LIMIT(descriptor)+1) * SEG_GRANULARITY(descriptor) - 1;
  if ( limit < base_address ) limit = 0xffffffff;

  if ( SEG_EXPAND_DOWN(descriptor) )
    {
      if ( SEG_G_BIT(descriptor) )
	seg_top = 0xffffffff;
      else
	{
	  seg_top = base_address + (1 << 20);
	  if ( seg_top < base_address ) seg_top = 0xffffffff;
	}
      access_limit =
	(address <= limit) || (address >= seg_top) ? 0 :
	  ((seg_top-address) >= 255 ? 255 : seg_top-address);
    }
  else
    {
      access_limit =
	(address > limit) || (address < base_address) ? 0 :
	  ((limit-address) >= 254 ? 255 : limit-address+1);
    }
  if ( SEG_EXECUTE_ONLY(descriptor) ||
      (!SEG_WRITE_PERM(descriptor) && (FPU_modrm & FPU_WRITE_BIT)) )
    {
      access_limit = 0;
    }
  return address;
}


/*
       MOD R/M byte:  MOD == 3 has a special use for the FPU
                      SIB byte used iff R/M = 100b

       7   6   5   4   3   2   1   0
       .....   .........   .........
        MOD    OPCODE(2)     R/M


       SIB byte

       7   6   5   4   3   2   1   0
       .....   .........   .........
        SS      INDEX        BASE

*/

void __user *FPU_get_address(u_char FPU_modrm, unsigned long *fpu_eip,
		  struct address *addr,
		  fpu_addr_modes addr_modes)
{
  u_char mod;
  unsigned rm = FPU_modrm & 7;
  long *cpu_reg_ptr;
  int address = 0;     /* Initialized just to stop compiler warnings. */

  /* Memory accessed via the cs selector is write protected
     in `non-segmented' 32 bit protected mode. */
  if ( !addr_modes.default_mode && (FPU_modrm & FPU_WRITE_BIT)
      && (addr_modes.override.segment == PREFIX_CS_) )
    {
      math_abort(FPU_info,SIGSEGV);
    }

  addr->selector = FPU_DS;   /* Default, for 32 bit non-segmented mode. */

  mod = (FPU_modrm >> 6) & 3;

  if (rm == 4 && mod != 3)
    {
      address = sib(mod, fpu_eip);
    }
  else
    {
      cpu_reg_ptr = & REG_(rm);
      switch (mod)
	{
	case 0:
	  if (rm == 5)
	    {
	      /* Special case: disp32 */
	      RE_ENTRANT_CHECK_OFF;
	      FPU_code_access_ok(4);
	      FPU_get_user(address, (unsigned long __user *) (*fpu_eip));
	      (*fpu_eip) += 4;
	      RE_ENTRANT_CHECK_ON;
	      addr->offset = address;
	      return (void __user *) address;
	    }
	  else
	    {
	      address = *cpu_reg_ptr;  /* Just return the contents
					  of the cpu register */
	      addr->offset = address;
	      return (void __user *) address;
	    }
	case 1:
	  /* 8 bit signed displacement */
	  RE_ENTRANT_CHECK_OFF;
	  FPU_code_access_ok(1);
	  FPU_get_user(address, (signed char __user *) (*fpu_eip));
	  RE_ENTRANT_CHECK_ON;
	  (*fpu_eip)++;
	  break;
	case 2:
	  /* 32 bit displacement */
	  RE_ENTRANT_CHECK_OFF;
	  FPU_code_access_ok(4);
	  FPU_get_user(address, (long __user *) (*fpu_eip));
	  (*fpu_eip) += 4;
	  RE_ENTRANT_CHECK_ON;
	  break;
	case 3:
	  /* Not legal for the FPU */
	  EXCEPTION(EX_Invalid);
	}
      address += *cpu_reg_ptr;
    }

  addr->offset = address;

  switch ( addr_modes.default_mode )
    {
    case 0:
      break;
    case VM86:
      address += vm86_segment(addr_modes.override.segment, addr);
      break;
    case PM16:
    case SEG32:
      address = pm_address(FPU_modrm, addr_modes.override.segment,
			   addr, address);
      break;
    default:
      EXCEPTION(EX_INTERNAL|0x133);
    }

  return (void __user *)address;
}


void __user *FPU_get_address_16(u_char FPU_modrm, unsigned long *fpu_eip,
		     struct address *addr,
		     fpu_addr_modes addr_modes)
{
  u_char mod;
  unsigned rm = FPU_modrm & 7;
  int address = 0;     /* Default used for mod == 0 */

  /* Memory accessed via the cs selector is write protected
     in `non-segmented' 32 bit protected mode. */
  if ( !addr_modes.default_mode && (FPU_modrm & FPU_WRITE_BIT)
      && (addr_modes.override.segment == PREFIX_CS_) )
    {
      math_abort(FPU_info,SIGSEGV);
    }

  addr->selector = FPU_DS;   /* Default, for 32 bit non-segmented mode. */

  mod = (FPU_modrm >> 6) & 3;

  switch (mod)
    {
    case 0:
      if (rm == 6)
	{
	  /* Special case: disp16 */
	  RE_ENTRANT_CHECK_OFF;
	  FPU_code_access_ok(2);
	  FPU_get_user(address, (unsigned short __user *) (*fpu_eip));
	  (*fpu_eip) += 2;
	  RE_ENTRANT_CHECK_ON;
	  goto add_segment;
	}
      break;
    case 1:
      /* 8 bit signed displacement */
      RE_ENTRANT_CHECK_OFF;
      FPU_code_access_ok(1);
      FPU_get_user(address, (signed char __user *) (*fpu_eip));
      RE_ENTRANT_CHECK_ON;
      (*fpu_eip)++;
      break;
    case 2:
      /* 16 bit displacement */
      RE_ENTRANT_CHECK_OFF;
      FPU_code_access_ok(2);
      FPU_get_user(address, (unsigned short __user *) (*fpu_eip));
      (*fpu_eip) += 2;
      RE_ENTRANT_CHECK_ON;
      break;
    case 3:
      /* Not legal for the FPU */
      EXCEPTION(EX_Invalid);
      break;
    }
  switch ( rm )
    {
    case 0:
      address += FPU_info->___ebx + FPU_info->___esi;
      break;
    case 1:
      address += FPU_info->___ebx + FPU_info->___edi;
      break;
    case 2:
      address += FPU_info->___ebp + FPU_info->___esi;
      if ( addr_modes.override.segment == PREFIX_DEFAULT )
	addr_modes.override.segment = PREFIX_SS_;
      break;
    case 3:
      address += FPU_info->___ebp + FPU_info->___edi;
      if ( addr_modes.override.segment == PREFIX_DEFAULT )
	addr_modes.override.segment = PREFIX_SS_;
      break;
    case 4:
      address += FPU_info->___esi;
      break;
    case 5:
      address += FPU_info->___edi;
      break;
    case 6:
      address += FPU_info->___ebp;
      if ( addr_modes.override.segment == PREFIX_DEFAULT )
	addr_modes.override.segment = PREFIX_SS_;
      break;
    case 7:
      address += FPU_info->___ebx;
      break;
    }

 add_segment:
  address &= 0xffff;

  addr->offset = address;

  switch ( addr_modes.default_mode )
    {
    case 0:
      break;
    case VM86:
      address += vm86_segment(addr_modes.override.segment, addr);
      break;
    case PM16:
    case SEG32:
      address = pm_address(FPU_modrm, addr_modes.override.segment,
			   addr, address);
      break;
    default:
      EXCEPTION(EX_INTERNAL|0x131);
    }

  return (void __user *)address ;
}
Commit	Line	Data
1da177e4 LT	1	/*---------------------------------------------------------------------------+
	2	\| get_address.c \|
	3	\| \|
	4	\| Get the effective address from an FPU instruction. \|
	5	\| \|
	6	\| Copyright (C) 1992,1993,1994,1997 \|
	7	\| W. Metzenthen, 22 Parker St, Ormond, Vic 3163, \|
	8	\| Australia. E-mail billm@suburbia.net \|
	9	\| \|
	10	\| \|
	11	+---------------------------------------------------------------------------*/
	12
	13	/*---------------------------------------------------------------------------+
	14	\| Note: \|
	15	\| The file contains code which accesses user memory. \|
	16	\| Emulator static data may change when user memory is accessed, due to \|
	17	\| other processes using the emulator while swapping is in progress. \|
	18	+---------------------------------------------------------------------------*/
	19
	20
	21	#include <linux/stddef.h>
	22
	23	#include <asm/uaccess.h>
	24	#include <asm/desc.h>
	25
	26	#include "fpu_system.h"
	27	#include "exception.h"
	28	#include "fpu_emu.h"
	29
	30
	31	#define FPU_WRITE_BIT 0x10
	32
	33	static int reg_offset[] = {
	34	offsetof(struct info,___eax),
	35	offsetof(struct info,___ecx),
	36	offsetof(struct info,___edx),
	37	offsetof(struct info,___ebx),
	38	offsetof(struct info,___esp),
	39	offsetof(struct info,___ebp),
	40	offsetof(struct info,___esi),
	41	offsetof(struct info,___edi)
	42	};
	43
	44	#define REG_(x) ((long )(reg_offset[(x)]+(u_char *) FPU_info))
	45
	46	static int reg_offset_vm86[] = {
	47	offsetof(struct info,___cs),
	48	offsetof(struct info,___vm86_ds),
	49	offsetof(struct info,___vm86_es),
	50	offsetof(struct info,___vm86_fs),
	51	offsetof(struct info,___vm86_gs),
	52	offsetof(struct info,___ss),
	53	offsetof(struct info,___vm86_ds)
	54	};
	55
	56	#define VM86_REG_(x) ((unsigned short ) \
	57	(reg_offset_vm86[((unsigned)x)]+(u_char *) FPU_info))
	58
	59	/* These are dummy, fs and gs are not saved on the stack. */
	60	#define ___FS ___ds
	61	#define ___GS ___ds
	62
	63	static int reg_offset_pm[] = {
	64	offsetof(struct info,___cs),
65	offsetof(struct info,___ds),
66	offsetof(struct info,___es),
67	offsetof(struct info,___FS),
68	offsetof(struct info,___GS),
69	offsetof(struct info,___ss),
70	offsetof(struct info,___ds)
71	};
72
73	#define PM_REG_(x) ((unsigned short ) \
74	(reg_offset_pm[((unsigned)x)]+(u_char *) FPU_info))
75
76
77	/* Decode the SIB byte. This function assumes mod != 0 */
78	static int sib(int mod, unsigned long *fpu_eip)
79	{
80	u_char ss,index,base;
81	long offset;
82
83	RE_ENTRANT_CHECK_OFF;
84	FPU_code_access_ok(1);
85	FPU_get_user(base, (u_char __user ) (fpu_eip)); /* The SIB byte */
86	RE_ENTRANT_CHECK_ON;
87	(*fpu_eip)++;
88	ss = base >> 6;
89	index = (base >> 3) & 7;
90	base &= 7;
91
92	if ((mod == 0) && (base == 5))
93	offset = 0; /* No base register */
94	else
95	offset = REG_(base);
96
97	if (index == 4)
98	{
99	/* No index register */
100	/* A non-zero ss is illegal */
101	if ( ss )
102	EXCEPTION(EX_Invalid);
103	}
104	else
105	{
106	offset += (REG_(index)) << ss;
107	}
108
109	if (mod == 1)
110	{
111	/* 8 bit signed displacement */
112	long displacement;
113	RE_ENTRANT_CHECK_OFF;
114	FPU_code_access_ok(1);
115	FPU_get_user(displacement, (signed char __user ) (fpu_eip));
116	offset += displacement;
117	RE_ENTRANT_CHECK_ON;
118	(*fpu_eip)++;
119	}
120	else if (mod == 2 \|\| base == 5) /* The second condition also has mod==0 */
121	{
122	/* 32 bit displacement */
123	long displacement;
124	RE_ENTRANT_CHECK_OFF;
125	FPU_code_access_ok(4);
126	FPU_get_user(displacement, (long __user ) (fpu_eip));
127	offset += displacement;
128	RE_ENTRANT_CHECK_ON;
129	(*fpu_eip) += 4;
130	}
131
132	return offset;
133	}
134
135
136	static unsigned long vm86_segment(u_char segment,
137	struct address *addr)
138	{
139	segment--;
140	#ifdef PARANOID
141	if ( segment > PREFIX_SS_ )
142	{
143	EXCEPTION(EX_INTERNAL\|0x130);
144	math_abort(FPU_info,SIGSEGV);
145	}
146	#endif /* PARANOID */
147	addr->selector = VM86_REG_(segment);
148	return (unsigned long)VM86_REG_(segment) << 4;
149	}
150
151
152	/* This should work for 16 and 32 bit protected mode. */
153	static long pm_address(u_char FPU_modrm, u_char segment,
154	struct address *addr, long offset)
155	{
156	struct desc_struct descriptor;
157	unsigned long base_address, limit, address, seg_top;
1da177e4 LT	158
	159	segment--;
	160
	161	#ifdef PARANOID
	162	/* segment is unsigned, so this also detects if segment was 0: */
	163	if ( segment > PREFIX_SS_ )
	164	{
	165	EXCEPTION(EX_INTERNAL\|0x132);
	166	math_abort(FPU_info,SIGSEGV);
	167	}
	168	#endif /* PARANOID */
	169
	170	switch ( segment )
	171	{
	172	/* fs and gs aren't used by the kernel, so they still have their
	173	user-space values. */
	174	case PREFIX_FS_-1:
4d37e7e3 ZA	175	/* N.B. - movl %seg, mem is a 2 byte write regardless of prefix */
4d37e7e3 ZA	176	savesegment(fs, addr->selector);
1da177e4 LT	177	break;
1da177e4 LT	178	case PREFIX_GS_-1:
4d37e7e3	179	savesegment(gs, addr->selector);
1da177e4 LT	180	break;
	181	default:
	182	addr->selector = PM_REG_(segment);
	183	}
	184
	185	descriptor = LDT_DESCRIPTOR(PM_REG_(segment));
	186	base_address = SEG_BASE_ADDR(descriptor);
	187	address = base_address + offset;
	188	limit = base_address
	189	+ (SEG_LIMIT(descriptor)+1) * SEG_GRANULARITY(descriptor) - 1;
	190	if ( limit < base_address ) limit = 0xffffffff;
	191
	192	if ( SEG_EXPAND_DOWN(descriptor) )
	193	{
	194	if ( SEG_G_BIT(descriptor) )
	195	seg_top = 0xffffffff;
	196	else
	197	{
	198	seg_top = base_address + (1 << 20);
	199	if ( seg_top < base_address ) seg_top = 0xffffffff;
	200	}
	201	access_limit =
	202	(address <= limit) \|\| (address >= seg_top) ? 0 :
	203	((seg_top-address) >= 255 ? 255 : seg_top-address);
	204	}
	205	else
	206	{
	207	access_limit =
	208	(address > limit) \|\| (address < base_address) ? 0 :
	209	((limit-address) >= 254 ? 255 : limit-address+1);
	210	}
	211	if ( SEG_EXECUTE_ONLY(descriptor) \|\|
	212	(!SEG_WRITE_PERM(descriptor) && (FPU_modrm & FPU_WRITE_BIT)) )
	213	{
	214	access_limit = 0;
	215	}
	216	return address;
	217	}
	218
	219
	220	/*
	221	MOD R/M byte: MOD == 3 has a special use for the FPU
	222	SIB byte used iff R/M = 100b
	223
	224	7 6 5 4 3 2 1 0
	225	..... ......... .........
	226	MOD OPCODE(2) R/M
	227
	228
	229	SIB byte
	230
	231	7 6 5 4 3 2 1 0
	232	..... ......... .........
	233	SS INDEX BASE
	234
	235	*/
	236
	237	void __user FPU_get_address(u_char FPU_modrm, unsigned long fpu_eip,
	238	struct address *addr,
	239	fpu_addr_modes addr_modes)
	240	{
	241	u_char mod;
	242	unsigned rm = FPU_modrm & 7;
	243	long *cpu_reg_ptr;
244	int address = 0; /* Initialized just to stop compiler warnings. */
245
246	/* Memory accessed via the cs selector is write protected
247	in `non-segmented' 32 bit protected mode. */
248	if ( !addr_modes.default_mode && (FPU_modrm & FPU_WRITE_BIT)
249	&& (addr_modes.override.segment == PREFIX_CS_) )
250	{
251	math_abort(FPU_info,SIGSEGV);
252	}
253
254	addr->selector = FPU_DS; /* Default, for 32 bit non-segmented mode. */
255
256	mod = (FPU_modrm >> 6) & 3;
257
258	if (rm == 4 && mod != 3)
259	{
260	address = sib(mod, fpu_eip);
261	}
262	else
263	{
264	cpu_reg_ptr = & REG_(rm);
265	switch (mod)
266	{
267	case 0:
268	if (rm == 5)
269	{
270	/* Special case: disp32 */
271	RE_ENTRANT_CHECK_OFF;
272	FPU_code_access_ok(4);
273	FPU_get_user(address, (unsigned long __user ) (fpu_eip));
274	(*fpu_eip) += 4;
275	RE_ENTRANT_CHECK_ON;
276	addr->offset = address;
277	return (void __user *) address;
278	}
279	else
280	{
281	address = cpu_reg_ptr; / Just return the contents
282	of the cpu register */
283	addr->offset = address;
284	return (void __user *) address;
285	}
286	case 1:
287	/* 8 bit signed displacement */
288	RE_ENTRANT_CHECK_OFF;
289	FPU_code_access_ok(1);
290	FPU_get_user(address, (signed char __user ) (fpu_eip));
291	RE_ENTRANT_CHECK_ON;
292	(*fpu_eip)++;
293	break;
294	case 2:
295	/* 32 bit displacement */
296	RE_ENTRANT_CHECK_OFF;
297	FPU_code_access_ok(4);
298	FPU_get_user(address, (long __user ) (fpu_eip));
299	(*fpu_eip) += 4;
300	RE_ENTRANT_CHECK_ON;
301	break;
302	case 3:
303	/* Not legal for the FPU */
304	EXCEPTION(EX_Invalid);
305	}
306	address += *cpu_reg_ptr;
307	}
308
309	addr->offset = address;
310
311	switch ( addr_modes.default_mode )
312	{
313	case 0:
314	break;
315	case VM86:
316	address += vm86_segment(addr_modes.override.segment, addr);
317	break;
318	case PM16:
319	case SEG32:
320	address = pm_address(FPU_modrm, addr_modes.override.segment,
321	addr, address);
322	break;
323	default:
324	EXCEPTION(EX_INTERNAL\|0x133);
325	}
326
327	return (void __user *)address;
328	}
329
330
331	void __user FPU_get_address_16(u_char FPU_modrm, unsigned long fpu_eip,
332	struct address *addr,
333	fpu_addr_modes addr_modes)
334	{
335	u_char mod;
336	unsigned rm = FPU_modrm & 7;
337	int address = 0; /* Default used for mod == 0 */
338
339	/* Memory accessed via the cs selector is write protected
340	in `non-segmented' 32 bit protected mode. */
341	if ( !addr_modes.default_mode && (FPU_modrm & FPU_WRITE_BIT)
342	&& (addr_modes.override.segment == PREFIX_CS_) )
343	{
344	math_abort(FPU_info,SIGSEGV);
345	}
346
347	addr->selector = FPU_DS; /* Default, for 32 bit non-segmented mode. */
348
349	mod = (FPU_modrm >> 6) & 3;
350
351	switch (mod)
352	{
353	case 0:
354	if (rm == 6)
355	{
356	/* Special case: disp16 */
357	RE_ENTRANT_CHECK_OFF;
358	FPU_code_access_ok(2);
359	FPU_get_user(address, (unsigned short __user ) (fpu_eip));
360	(*fpu_eip) += 2;
361	RE_ENTRANT_CHECK_ON;
362	goto add_segment;
363	}
364	break;
365	case 1:
366	/* 8 bit signed displacement */
367	RE_ENTRANT_CHECK_OFF;
368	FPU_code_access_ok(1);
369	FPU_get_user(address, (signed char __user ) (fpu_eip));
370	RE_ENTRANT_CHECK_ON;
371	(*fpu_eip)++;
372	break;
373	case 2:
374	/* 16 bit displacement */
375	RE_ENTRANT_CHECK_OFF;
376	FPU_code_access_ok(2);
377	FPU_get_user(address, (unsigned short __user ) (fpu_eip));
378	(*fpu_eip) += 2;
379	RE_ENTRANT_CHECK_ON;
380	break;
381	case 3:
382	/* Not legal for the FPU */
383	EXCEPTION(EX_Invalid);
384	break;
385	}
386	switch ( rm )
387	{
388	case 0:
389	address += FPU_info->___ebx + FPU_info->___esi;
390	break;
391	case 1:
392	address += FPU_info->___ebx + FPU_info->___edi;
393	break;
394	case 2:
395	address += FPU_info->___ebp + FPU_info->___esi;
396	if ( addr_modes.override.segment == PREFIX_DEFAULT )
397	addr_modes.override.segment = PREFIX_SS_;
398	break;
399	case 3:
400	address += FPU_info->___ebp + FPU_info->___edi;
401	if ( addr_modes.override.segment == PREFIX_DEFAULT )
402	addr_modes.override.segment = PREFIX_SS_;
403	break;
404	case 4:
405	address += FPU_info->___esi;
406	break;
407	case 5:
408	address += FPU_info->___edi;
409	break;
410	case 6:
411	address += FPU_info->___ebp;
412	if ( addr_modes.override.segment == PREFIX_DEFAULT )
413	addr_modes.override.segment = PREFIX_SS_;
414	break;
415	case 7:
416	address += FPU_info->___ebx;
417	break;
418	}
419
420	add_segment:
421	address &= 0xffff;
422
423	addr->offset = address;
424
425	switch ( addr_modes.default_mode )
426	{
427	case 0:
428	break;
429	case VM86:
430	address += vm86_segment(addr_modes.override.segment, addr);
431	break;
432	case PM16:
433	case SEG32:
434	address = pm_address(FPU_modrm, addr_modes.override.segment,
435	addr, address);
436	break;
437	default:
438	EXCEPTION(EX_INTERNAL\|0x131);
439	}
440
441	return (void __user *)address ;
442	}