i386: move math-emu

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 761 insertions, 0 deletions

diff --git a/arch/x86/math-emu/fpu_entry.c b/arch/x86/math-emu/fpu_entry.c
new file mode 100644
index 000000000000..1853524c8b57
--- /dev/null
+++ b/arch/x86/math-emu/fpu_entry.c
@@ -0,0 +1,761 @@
+/*---------------------------------------------------------------------------+
+ |  fpu_entry.c                                                              |
+ |                                                                           |
+ | The entry functions for wm-FPU-emu                                        |
+ |                                                                           |
+ | Copyright (C) 1992,1993,1994,1996,1997                                    |
+ |                  W. Metzenthen, 22 Parker St, Ormond, Vic 3163, Australia |
+ |                  E-mail   billm@suburbia.net                              |
+ |                                                                           |
+ | See the files "README" and "COPYING" for further copyright and warranty   |
+ | information.                                                              |
+ |                                                                           |
+ +---------------------------------------------------------------------------*/
+
+/*---------------------------------------------------------------------------+
+ | 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.      |
+ +---------------------------------------------------------------------------*/
+
+/*---------------------------------------------------------------------------+
+ | math_emulate(), restore_i387_soft() and save_i387_soft() are the only     |
+ | entry points for wm-FPU-emu.                                              |
+ +---------------------------------------------------------------------------*/
+
+#include <linux/signal.h>
+#include <linux/ptrace.h>
+
+#include <asm/uaccess.h>
+#include <asm/desc.h>
+
+#include "fpu_system.h"
+#include "fpu_emu.h"
+#include "exception.h"
+#include "control_w.h"
+#include "status_w.h"
+
+#define __BAD__ FPU_illegal   /* Illegal on an 80486, causes SIGILL */
+
+#ifndef NO_UNDOC_CODE    /* Un-documented FPU op-codes supported by default. */
+
+/* WARNING: These codes are not documented by Intel in their 80486 manual
+   and may not work on FPU clones or later Intel FPUs. */
+
+/* Changes to support the un-doc codes provided by Linus Torvalds. */
+
+#define _d9_d8_ fstp_i    /* unofficial code (19) */
+#define _dc_d0_ fcom_st   /* unofficial code (14) */
+#define _dc_d8_ fcompst   /* unofficial code (1c) */
+#define _dd_c8_ fxch_i    /* unofficial code (0d) */
+#define _de_d0_ fcompst   /* unofficial code (16) */
+#define _df_c0_ ffreep    /* unofficial code (07) ffree + pop */
+#define _df_c8_ fxch_i    /* unofficial code (0f) */
+#define _df_d0_ fstp_i    /* unofficial code (17) */
+#define _df_d8_ fstp_i    /* unofficial code (1f) */
+
+static FUNC const st_instr_table[64] = {
+  fadd__,   fld_i_,     __BAD__, __BAD__, fadd_i,  ffree_,  faddp_,  _df_c0_,
+  fmul__,   fxch_i,     __BAD__, __BAD__, fmul_i,  _dd_c8_, fmulp_,  _df_c8_,
+  fcom_st,  fp_nop,     __BAD__, __BAD__, _dc_d0_, fst_i_,  _de_d0_, _df_d0_,
+  fcompst,  _d9_d8_,    __BAD__, __BAD__, _dc_d8_, fstp_i,  fcompp,  _df_d8_,
+  fsub__,   FPU_etc,    __BAD__, finit_,  fsubri,  fucom_,  fsubrp,  fstsw_,
+  fsubr_,   fconst,     fucompp, __BAD__, fsub_i,  fucomp,  fsubp_,  __BAD__,
+  fdiv__,   FPU_triga,  __BAD__, __BAD__, fdivri,  __BAD__, fdivrp,  __BAD__,
+  fdivr_,   FPU_trigb,  __BAD__, __BAD__, fdiv_i,  __BAD__, fdivp_,  __BAD__,
+};
+
+#else     /* Support only documented FPU op-codes */
+
+static FUNC const st_instr_table[64] = {
+  fadd__,   fld_i_,     __BAD__, __BAD__, fadd_i,  ffree_,  faddp_,  __BAD__,
+  fmul__,   fxch_i,     __BAD__, __BAD__, fmul_i,  __BAD__, fmulp_,  __BAD__,
+  fcom_st,  fp_nop,     __BAD__, __BAD__, __BAD__, fst_i_,  __BAD__, __BAD__,
+  fcompst,  __BAD__,    __BAD__, __BAD__, __BAD__, fstp_i,  fcompp,  __BAD__,
+  fsub__,   FPU_etc,    __BAD__, finit_,  fsubri,  fucom_,  fsubrp,  fstsw_,
+  fsubr_,   fconst,     fucompp, __BAD__, fsub_i,  fucomp,  fsubp_,  __BAD__,
+  fdiv__,   FPU_triga,  __BAD__, __BAD__, fdivri,  __BAD__, fdivrp,  __BAD__,
+  fdivr_,   FPU_trigb,  __BAD__, __BAD__, fdiv_i,  __BAD__, fdivp_,  __BAD__,
+};
+
+#endif /* NO_UNDOC_CODE */
+
+
+#define _NONE_ 0   /* Take no special action */
+#define _REG0_ 1   /* Need to check for not empty st(0) */
+#define _REGI_ 2   /* Need to check for not empty st(0) and st(rm) */
+#define _REGi_ 0   /* Uses st(rm) */
+#define _PUSH_ 3   /* Need to check for space to push onto stack */
+#define _null_ 4   /* Function illegal or not implemented */
+#define _REGIi 5   /* Uses st(0) and st(rm), result to st(rm) */
+#define _REGIp 6   /* Uses st(0) and st(rm), result to st(rm) then pop */
+#define _REGIc 0   /* Compare st(0) and st(rm) */
+#define _REGIn 0   /* Uses st(0) and st(rm), but handle checks later */
+
+#ifndef NO_UNDOC_CODE
+
+/* Un-documented FPU op-codes supported by default. (see above) */
+
+static u_char const type_table[64] = {
+  _REGI_, _NONE_, _null_, _null_, _REGIi, _REGi_, _REGIp, _REGi_,
+  _REGI_, _REGIn, _null_, _null_, _REGIi, _REGI_, _REGIp, _REGI_,
+  _REGIc, _NONE_, _null_, _null_, _REGIc, _REG0_, _REGIc, _REG0_,
+  _REGIc, _REG0_, _null_, _null_, _REGIc, _REG0_, _REGIc, _REG0_,
+  _REGI_, _NONE_, _null_, _NONE_, _REGIi, _REGIc, _REGIp, _NONE_,
+  _REGI_, _NONE_, _REGIc, _null_, _REGIi, _REGIc, _REGIp, _null_,
+  _REGI_, _NONE_, _null_, _null_, _REGIi, _null_, _REGIp, _null_,
+  _REGI_, _NONE_, _null_, _null_, _REGIi, _null_, _REGIp, _null_
+};
+
+#else     /* Support only documented FPU op-codes */
+
+static u_char const type_table[64] = {
+  _REGI_, _NONE_, _null_, _null_, _REGIi, _REGi_, _REGIp, _null_,
+  _REGI_, _REGIn, _null_, _null_, _REGIi, _null_, _REGIp, _null_,
+  _REGIc, _NONE_, _null_, _null_, _null_, _REG0_, _null_, _null_,
+  _REGIc, _null_, _null_, _null_, _null_, _REG0_, _REGIc, _null_,
+  _REGI_, _NONE_, _null_, _NONE_, _REGIi, _REGIc, _REGIp, _NONE_,
+  _REGI_, _NONE_, _REGIc, _null_, _REGIi, _REGIc, _REGIp, _null_,
+  _REGI_, _NONE_, _null_, _null_, _REGIi, _null_, _REGIp, _null_,
+  _REGI_, _NONE_, _null_, _null_, _REGIi, _null_, _REGIp, _null_
+};
+
+#endif /* NO_UNDOC_CODE */
+
+
+#ifdef RE_ENTRANT_CHECKING
+u_char emulating=0;
+#endif /* RE_ENTRANT_CHECKING */
+
+static int valid_prefix(u_char *Byte, u_char __user **fpu_eip,
+                        overrides *override);
+
+asmlinkage void math_emulate(long arg)
+{
+  u_char  FPU_modrm, byte1;
+  unsigned short code;
+  fpu_addr_modes addr_modes;
+  int unmasked;
+  FPU_REG loaded_data;
+  FPU_REG *st0_ptr;
+  u_char          loaded_tag, st0_tag;
+  void __user *data_address;
+  struct address data_sel_off;
+  struct address entry_sel_off;
+  unsigned long code_base = 0;
+  unsigned long code_limit = 0;  /* Initialized to stop compiler warnings */
+  struct desc_struct code_descriptor;
+
+#ifdef RE_ENTRANT_CHECKING
+  if ( emulating )
+    {
+      printk("ERROR: wm-FPU-emu is not RE-ENTRANT!\n");
+    }
+  RE_ENTRANT_CHECK_ON;
+#endif /* RE_ENTRANT_CHECKING */
+
+  if (!used_math())
+    {
+      finit();
+      set_used_math();
+    }
+
+  SETUP_DATA_AREA(arg);
+
+  FPU_ORIG_EIP = FPU_EIP;
+
+  if ( (FPU_EFLAGS & 0x00020000) != 0 )
+    {
+      /* Virtual 8086 mode */
+      addr_modes.default_mode = VM86;
+      FPU_EIP += code_base = FPU_CS << 4;
+      code_limit = code_base + 0xffff;  /* Assumes code_base <= 0xffff0000 */
+    }
+  else if ( FPU_CS == __USER_CS && FPU_DS == __USER_DS )
+    {
+      addr_modes.default_mode = 0;
+    }
+  else if ( FPU_CS == __KERNEL_CS )
+    {
+      printk("math_emulate: %04x:%08lx\n",FPU_CS,FPU_EIP);
+      panic("Math emulation needed in kernel");
+    }
+  else
+    {
+
+      if ( (FPU_CS & 4) != 4 )   /* Must be in the LDT */
+        {
+          /* Can only handle segmented addressing via the LDT
+             for now, and it must be 16 bit */
+          printk("FPU emulator: Unsupported addressing mode\n");
+          math_abort(FPU_info, SIGILL);
+        }
+
+      code_descriptor = LDT_DESCRIPTOR(FPU_CS);
+      if ( SEG_D_SIZE(code_descriptor) )
+        {
+          /* The above test may be wrong, the book is not clear */
+          /* Segmented 32 bit protected mode */
+          addr_modes.default_mode = SEG32;
+        }
+      else
+        {
+          /* 16 bit protected mode */
+          addr_modes.default_mode = PM16;
+        }
+      FPU_EIP += code_base = SEG_BASE_ADDR(code_descriptor);
+      code_limit = code_base
+        + (SEG_LIMIT(code_descriptor)+1) * SEG_GRANULARITY(code_descriptor)
+          - 1;
+      if ( code_limit < code_base ) code_limit = 0xffffffff;
+    }
+
+  FPU_lookahead = 1;
+  if (current->ptrace & PT_PTRACED)
+    FPU_lookahead = 0;
+
+  if ( !valid_prefix(&byte1, (u_char __user **)&FPU_EIP,
+                     &addr_modes.override) )
+    {
+      RE_ENTRANT_CHECK_OFF;
+      printk("FPU emulator: Unknown prefix byte 0x%02x, probably due to\n"
+             "FPU emulator: self-modifying code! (emulation impossible)\n",
+             byte1);
+      RE_ENTRANT_CHECK_ON;
+      EXCEPTION(EX_INTERNAL|0x126);
+      math_abort(FPU_info,SIGILL);
+    }
+
+do_another_FPU_instruction:
+
+  no_ip_update = 0;
+
+  FPU_EIP++;  /* We have fetched the prefix and first code bytes. */
+
+  if ( addr_modes.default_mode )
+    {
+      /* This checks for the minimum instruction bytes.
+         We also need to check any extra (address mode) code access. */
+      if ( FPU_EIP > code_limit )
+        math_abort(FPU_info,SIGSEGV);
+    }
+
+  if ( (byte1 & 0xf8) != 0xd8 )
+    {
+      if ( byte1 == FWAIT_OPCODE )
+        {
+          if (partial_status & SW_Summary)
+            goto do_the_FPU_interrupt;
+          else
+            goto FPU_fwait_done;
+        }
+#ifdef PARANOID
+      EXCEPTION(EX_INTERNAL|0x128);
+      math_abort(FPU_info,SIGILL);
+#endif /* PARANOID */
+    }
+
+  RE_ENTRANT_CHECK_OFF;
+  FPU_code_access_ok(1);
+  FPU_get_user(FPU_modrm, (u_char __user *) FPU_EIP);
+  RE_ENTRANT_CHECK_ON;
+  FPU_EIP++;
+
+  if (partial_status & SW_Summary)
+    {
+      /* Ignore the error for now if the current instruction is a no-wait
+         control instruction */
+      /* The 80486 manual contradicts itself on this topic,
+         but a real 80486 uses the following instructions:
+         fninit, fnstenv, fnsave, fnstsw, fnstenv, fnclex.
+       */
+      code = (FPU_modrm << 8) | byte1;
+      if ( ! ( (((code & 0xf803) == 0xe003) ||    /* fnclex, fninit, fnstsw */
+                (((code & 0x3003) == 0x3001) &&   /* fnsave, fnstcw, fnstenv,
+                                                     fnstsw */
+                 ((code & 0xc000) != 0xc000))) ) )
+        {
+          /*
+           *  We need to simulate the action of the kernel to FPU
+           *  interrupts here.
+           */
+        do_the_FPU_interrupt:
+
+          FPU_EIP = FPU_ORIG_EIP;       /* Point to current FPU instruction. */
+
+          RE_ENTRANT_CHECK_OFF;
+          current->thread.trap_no = 16;
+          current->thread.error_code = 0;
+          send_sig(SIGFPE, current, 1);
+          return;
+        }
+    }
+
+  entry_sel_off.offset = FPU_ORIG_EIP;
+  entry_sel_off.selector = FPU_CS;
+  entry_sel_off.opcode = (byte1 << 8) | FPU_modrm;
+
+  FPU_rm = FPU_modrm & 7;
+
+  if ( FPU_modrm < 0300 )
+    {
+      /* All of these instructions use the mod/rm byte to get a data address */
+
+      if ( (addr_modes.default_mode & SIXTEEN)
+          ^ (addr_modes.override.address_size == ADDR_SIZE_PREFIX) )
+        data_address = FPU_get_address_16(FPU_modrm, &FPU_EIP, &data_sel_off,
+                                          addr_modes);
+      else
+        data_address = FPU_get_address(FPU_modrm, &FPU_EIP, &data_sel_off,
+                                       addr_modes);
+
+      if ( addr_modes.default_mode )
+        {
+          if ( FPU_EIP-1 > code_limit )
+            math_abort(FPU_info,SIGSEGV);
+        }
+
+      if ( !(byte1 & 1) )
+        {
+          unsigned short status1 = partial_status;
+
+          st0_ptr = &st(0);
+          st0_tag = FPU_gettag0();
+
+          /* Stack underflow has priority */
+          if ( NOT_EMPTY_ST0 )
+            {
+              if ( addr_modes.default_mode & PROTECTED )
+                {
+                  /* This table works for 16 and 32 bit protected mode */
+                  if ( access_limit < data_sizes_16[(byte1 >> 1) & 3] )
+                    math_abort(FPU_info,SIGSEGV);
+                }
+
+              unmasked = 0;  /* Do this here to stop compiler warnings. */
+              switch ( (byte1 >> 1) & 3 )
+                {
+                case 0:
+                  unmasked = FPU_load_single((float __user *)data_address,
+                                             &loaded_data);
+                  loaded_tag = unmasked & 0xff;
+                  unmasked &= ~0xff;
+                  break;
+                case 1:
+                  loaded_tag = FPU_load_int32((long __user *)data_address, &loaded_data);
+                  break;
+                case 2:
+                  unmasked = FPU_load_double((double __user *)data_address,
+                                             &loaded_data);
+                  loaded_tag = unmasked & 0xff;
+                  unmasked &= ~0xff;
+                  break;
+                case 3:
+                default:  /* Used here to suppress gcc warnings. */
+                  loaded_tag = FPU_load_int16((short __user *)data_address, &loaded_data);
+                  break;
+                }
+
+              /* No more access to user memory, it is safe
+                 to use static data now */
+
+              /* NaN operands have the next priority. */
+              /* We have to delay looking at st(0) until after
+                 loading the data, because that data might contain an SNaN */
+              if ( ((st0_tag == TAG_Special) && isNaN(st0_ptr)) ||
+                  ((loaded_tag == TAG_Special) && isNaN(&loaded_data)) )
+                {
+                  /* Restore the status word; we might have loaded a
+                     denormal. */
+                  partial_status = status1;
+                  if ( (FPU_modrm & 0x30) == 0x10 )
+                    {
+                      /* fcom or fcomp */
+                      EXCEPTION(EX_Invalid);
+                      setcc(SW_C3 | SW_C2 | SW_C0);
+                      if ( (FPU_modrm & 0x08) && (control_word & CW_Invalid) )
+                        FPU_pop();             /* fcomp, masked, so we pop. */
+                    }
+                  else
+                    {
+                      if ( loaded_tag == TAG_Special )
+                        loaded_tag = FPU_Special(&loaded_data);
+#ifdef PECULIAR_486
+                      /* This is not really needed, but gives behaviour
+                         identical to an 80486 */
+                      if ( (FPU_modrm & 0x28) == 0x20 )
+                        /* fdiv or fsub */
+                        real_2op_NaN(&loaded_data, loaded_tag, 0, &loaded_data);
+                      else
+#endif /* PECULIAR_486 */ 
+                        /* fadd, fdivr, fmul, or fsubr */
+                        real_2op_NaN(&loaded_data, loaded_tag, 0, st0_ptr);
+                    }
+                  goto reg_mem_instr_done;
+                }
+
+              if ( unmasked && !((FPU_modrm & 0x30) == 0x10) )
+                {
+                  /* Is not a comparison instruction. */
+                  if ( (FPU_modrm & 0x38) == 0x38 )
+                    {
+                      /* fdivr */
+                      if ( (st0_tag == TAG_Zero) &&
+                           ((loaded_tag == TAG_Valid)
+                            || (loaded_tag == TAG_Special
+                                && isdenormal(&loaded_data))) )
+                        {
+                          if ( FPU_divide_by_zero(0, getsign(&loaded_data))
+                               < 0 )
+                            {
+                              /* We use the fact here that the unmasked
+                                 exception in the loaded data was for a
+                                 denormal operand */
+                              /* Restore the state of the denormal op bit */
+                              partial_status &= ~SW_Denorm_Op;
+                              partial_status |= status1 & SW_Denorm_Op;
+                            }
+                          else
+                            setsign(st0_ptr, getsign(&loaded_data));
+                        }
+                    }
+                  goto reg_mem_instr_done;
+                }
+
+              switch ( (FPU_modrm >> 3) & 7 )
+                {
+                case 0:         /* fadd */
+                  clear_C1();
+                  FPU_add(&loaded_data, loaded_tag, 0, control_word);
+                  break;
+                case 1:         /* fmul */
+                  clear_C1();
+                  FPU_mul(&loaded_data, loaded_tag, 0, control_word);
+                  break;
+                case 2:         /* fcom */
+                  FPU_compare_st_data(&loaded_data, loaded_tag);
+                  break;
+                case 3:         /* fcomp */
+                  if ( !FPU_compare_st_data(&loaded_data, loaded_tag)
+                       && !unmasked )
+                    FPU_pop();
+                  break;
+                case 4:         /* fsub */
+                  clear_C1();
+                  FPU_sub(LOADED|loaded_tag, (int)&loaded_data, control_word);
+                  break;
+                case 5:         /* fsubr */
+                  clear_C1();
+                  FPU_sub(REV|LOADED|loaded_tag, (int)&loaded_data, control_word);
+                  break;
+                case 6:         /* fdiv */
+                  clear_C1();
+                  FPU_div(LOADED|loaded_tag, (int)&loaded_data, control_word);
+                  break;
+                case 7:         /* fdivr */
+                  clear_C1();
+                  if ( st0_tag == TAG_Zero )
+                    partial_status = status1;  /* Undo any denorm tag,
+                                                  zero-divide has priority. */
+                  FPU_div(REV|LOADED|loaded_tag, (int)&loaded_data, control_word);
+                  break;
+                }
+            }
+          else
+            {
+              if ( (FPU_modrm & 0x30) == 0x10 )
+                {
+                  /* The instruction is fcom or fcomp */
+                  EXCEPTION(EX_StackUnder);
+                  setcc(SW_C3 | SW_C2 | SW_C0);
+                  if ( (FPU_modrm & 0x08) && (control_word & CW_Invalid) )
+                    FPU_pop();             /* fcomp */
+                }
+              else
+                FPU_stack_underflow();
+            }
+        reg_mem_instr_done:
+          operand_address = data_sel_off;
+        }
+      else
+        {
+          if ( !(no_ip_update =
+                 FPU_load_store(((FPU_modrm & 0x38) | (byte1 & 6)) >> 1,
+                                addr_modes, data_address)) )
+            {
+              operand_address = data_sel_off;
+            }
+        }
+
+    }
+  else
+    {
+      /* None of these instructions access user memory */
+      u_char instr_index = (FPU_modrm & 0x38) | (byte1 & 7);
+
+#ifdef PECULIAR_486
+      /* This is supposed to be undefined, but a real 80486 seems
+         to do this: */
+      operand_address.offset = 0;
+      operand_address.selector = FPU_DS;
+#endif /* PECULIAR_486 */
+
+      st0_ptr = &st(0);
+      st0_tag = FPU_gettag0();
+      switch ( type_table[(int) instr_index] )
+        {
+        case _NONE_:   /* also _REGIc: _REGIn */
+          break;
+        case _REG0_:
+          if ( !NOT_EMPTY_ST0 )
+            {
+              FPU_stack_underflow();
+              goto FPU_instruction_done;
+            }
+          break;
+        case _REGIi:
+          if ( !NOT_EMPTY_ST0 || !NOT_EMPTY(FPU_rm) )
+            {
+              FPU_stack_underflow_i(FPU_rm);
+              goto FPU_instruction_done;
+            }
+          break;
+        case _REGIp:
+          if ( !NOT_EMPTY_ST0 || !NOT_EMPTY(FPU_rm) )
+            {
+              FPU_stack_underflow_pop(FPU_rm);
+              goto FPU_instruction_done;
+            }
+          break;
+        case _REGI_:
+          if ( !NOT_EMPTY_ST0 || !NOT_EMPTY(FPU_rm) )
+            {
+              FPU_stack_underflow();
+              goto FPU_instruction_done;
+            }
+          break;
+        case _PUSH_:     /* Only used by the fld st(i) instruction */
+          break;
+        case _null_:
+          FPU_illegal();
+          goto FPU_instruction_done;
+        default:
+          EXCEPTION(EX_INTERNAL|0x111);
+          goto FPU_instruction_done;
+        }
+      (*st_instr_table[(int) instr_index])();
+
+FPU_instruction_done:
+      ;
+    }
+
+  if ( ! no_ip_update )
+    instruction_address = entry_sel_off;
+
+FPU_fwait_done:
+
+#ifdef DEBUG
+  RE_ENTRANT_CHECK_OFF;
+  FPU_printall();
+  RE_ENTRANT_CHECK_ON;
+#endif /* DEBUG */
+
+  if (FPU_lookahead && !need_resched())
+    {
+      FPU_ORIG_EIP = FPU_EIP - code_base;
+      if ( valid_prefix(&byte1, (u_char __user **)&FPU_EIP,
+                        &addr_modes.override) )
+        goto do_another_FPU_instruction;
+    }
+
+  if ( addr_modes.default_mode )
+    FPU_EIP -= code_base;
+
+  RE_ENTRANT_CHECK_OFF;
+}
+
+
+/* Support for prefix bytes is not yet complete. To properly handle
+   all prefix bytes, further changes are needed in the emulator code
+   which accesses user address space. Access to separate segments is
+   important for msdos emulation. */
+static int valid_prefix(u_char *Byte, u_char __user **fpu_eip,
+                        overrides *override)
+{
+  u_char byte;
+  u_char __user *ip = *fpu_eip;
+
+  *override = (overrides) { 0, 0, PREFIX_DEFAULT };       /* defaults */
+
+  RE_ENTRANT_CHECK_OFF;
+  FPU_code_access_ok(1);
+  FPU_get_user(byte, ip);
+  RE_ENTRANT_CHECK_ON;
+
+  while ( 1 )
+    {
+      switch ( byte )
+        {
+        case ADDR_SIZE_PREFIX:
+          override->address_size = ADDR_SIZE_PREFIX;
+          goto do_next_byte;
+
+        case OP_SIZE_PREFIX:
+          override->operand_size = OP_SIZE_PREFIX;
+          goto do_next_byte;
+
+        case PREFIX_CS:
+          override->segment = PREFIX_CS_;
+          goto do_next_byte;
+        case PREFIX_ES:
+          override->segment = PREFIX_ES_;
+          goto do_next_byte;
+        case PREFIX_SS:
+          override->segment = PREFIX_SS_;
+          goto do_next_byte;
+        case PREFIX_FS:
+          override->segment = PREFIX_FS_;
+          goto do_next_byte;
+        case PREFIX_GS:
+          override->segment = PREFIX_GS_;
+          goto do_next_byte;
+        case PREFIX_DS:
+          override->segment = PREFIX_DS_;
+          goto do_next_byte;
+
+/* lock is not a valid prefix for FPU instructions,
+   let the cpu handle it to generate a SIGILL. */
+/*      case PREFIX_LOCK: */
+
+          /* rep.. prefixes have no meaning for FPU instructions */
+        case PREFIX_REPE:
+        case PREFIX_REPNE:
+
+        do_next_byte:
+          ip++;
+          RE_ENTRANT_CHECK_OFF;
+          FPU_code_access_ok(1);
+          FPU_get_user(byte, ip);
+          RE_ENTRANT_CHECK_ON;
+          break;
+        case FWAIT_OPCODE:
+          *Byte = byte;
+          return 1;
+        default:
+          if ( (byte & 0xf8) == 0xd8 )
+            {
+              *Byte = byte;
+              *fpu_eip = ip;
+              return 1;
+            }
+          else
+            {
+              /* Not a valid sequence of prefix bytes followed by
+                 an FPU instruction. */
+              *Byte = byte;  /* Needed for error message. */
+              return 0;
+            }
+        }
+    }
+}
+
+
+void math_abort(struct info * info, unsigned int signal)
+{
+        FPU_EIP = FPU_ORIG_EIP;
+        current->thread.trap_no = 16;
+        current->thread.error_code = 0;
+        send_sig(signal,current,1);
+        RE_ENTRANT_CHECK_OFF;
+        __asm__("movl %0,%%esp ; ret": :"g" (((long) info)-4));
+#ifdef PARANOID
+      printk("ERROR: wm-FPU-emu math_abort failed!\n");
+#endif /* PARANOID */
+}
+
+
+
+#define S387 ((struct i387_soft_struct *)s387)
+#define sstatus_word() \
+  ((S387->swd & ~SW_Top & 0xffff) | ((S387->ftop << SW_Top_Shift) & SW_Top))
+
+int restore_i387_soft(void *s387, struct _fpstate __user *buf)
+{
+  u_char __user *d = (u_char __user *)buf;
+  int offset, other, i, tags, regnr, tag, newtop;
+
+  RE_ENTRANT_CHECK_OFF;
+  FPU_access_ok(VERIFY_READ, d, 7*4 + 8*10);
+  if (__copy_from_user(&S387->cwd, d, 7*4))
+    return -1;
+  RE_ENTRANT_CHECK_ON;
+
+  d += 7*4;
+
+  S387->ftop = (S387->swd >> SW_Top_Shift) & 7;
+  offset = (S387->ftop & 7) * 10;
+  other = 80 - offset;
+
+  RE_ENTRANT_CHECK_OFF;
+  /* Copy all registers in stack order. */
+  if (__copy_from_user(((u_char *)&S387->st_space)+offset, d, other))
+    return -1;
+  if ( offset )
+    if (__copy_from_user((u_char *)&S387->st_space, d+other, offset))
+      return -1;
+  RE_ENTRANT_CHECK_ON;
+
+  /* The tags may need to be corrected now. */
+  tags = S387->twd;
+  newtop = S387->ftop;
+  for ( i = 0; i < 8; i++ )
+    {
+      regnr = (i+newtop) & 7;
+      if ( ((tags >> ((regnr & 7)*2)) & 3) != TAG_Empty )
+        {
+          /* The loaded data over-rides all other cases. */
+          tag = FPU_tagof((FPU_REG *)((u_char *)S387->st_space + 10*regnr));
+          tags &= ~(3 << (regnr*2));
+          tags |= (tag & 3) << (regnr*2);
+        }
+    }
+  S387->twd = tags;
+
+  return 0;
+}
+
+
+int save_i387_soft(void *s387, struct _fpstate __user * buf)
+{
+  u_char __user *d = (u_char __user *)buf;
+  int offset = (S387->ftop & 7) * 10, other = 80 - offset;
+
+  RE_ENTRANT_CHECK_OFF;
+  FPU_access_ok(VERIFY_WRITE, d, 7*4 + 8*10);
+#ifdef PECULIAR_486
+  S387->cwd &= ~0xe080;
+  /* An 80486 sets nearly all of the reserved bits to 1. */
+  S387->cwd |= 0xffff0040;
+  S387->swd = sstatus_word() | 0xffff0000;
+  S387->twd |= 0xffff0000;
+  S387->fcs &= ~0xf8000000;
+  S387->fos |= 0xffff0000;
+#endif /* PECULIAR_486 */
+  if (__copy_to_user(d, &S387->cwd, 7*4))
+    return -1;
+  RE_ENTRANT_CHECK_ON;
+
+  d += 7*4;
+
+  RE_ENTRANT_CHECK_OFF;
+  /* Copy all registers in stack order. */
+  if (__copy_to_user(d, ((u_char *)&S387->st_space)+offset, other))
+    return -1;
+  if ( offset )
+    if (__copy_to_user(d+other, (u_char *)&S387->st_space, offset))
+      return -1;
+  RE_ENTRANT_CHECK_ON;
+
+  return 1;
+}