arch/arm26/nwfpe/fpmodule.c

   1
   2 /*
   3     NetWinder Floating Point Emulator
   4     (c) Rebel.com, 1998-1999
   5     (c) Philip Blundell, 1998-1999
   6
   7     Direct questions, comments to Scott Bambrough <scottb@netwinder.org>
   8
   9     This program is free software; you can redistribute it and/or modify
  10     it under the terms of the GNU General Public License as published by
  11     the Free Software Foundation; either version 2 of the License, or
  12     (at your option) any later version.
  13
  14     This program is distributed in the hope that it will be useful,
  15     but WITHOUT ANY WARRANTY; without even the implied warranty of
  16     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17     GNU General Public License for more details.
  18
  19     You should have received a copy of the GNU General Public License
  20     along with this program; if not, write to the Free Software
  21     Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  22 */
  23
  24 #include "fpa11.h"
  25
  26 #include <linux/module.h>
  27 #include <linux/version.h>
  28
  29 /* XXX */
  30 #include <linux/errno.h>
  31 #include <linux/types.h>
  32 #include <linux/kernel.h>
  33 #include <linux/signal.h>
  34 #include <linux/sched.h>
  35 #include <linux/init.h>
  36 /* XXX */
  37
  38 #include "softfloat.h"
  39 #include "fpopcode.h"
  40 #include "fpmodule.h"
  41 #include "fpa11.inl"
  42
  43 /* kernel symbols required for signal handling */
  44 typedef struct task_struct*     PTASK;
  45
  46 #ifdef MODULE
  47 void fp_send_sig(unsigned long sig, PTASK p, int priv);
  48
  49 MODULE_AUTHOR("Scott Bambrough <scottb@rebel.com>");
  50 MODULE_DESCRIPTION("NWFPE floating point emulator");
  51
  52 #else
  53 #define fp_send_sig     send_sig
  54 #define kern_fp_enter   fp_enter
  55
  56 extern char fpe_type[];
  57 #endif
  58
  59 /* kernel function prototypes required */
  60 void fp_setup(void);
  61
  62 /* external declarations for saved kernel symbols */
  63 extern void (*kern_fp_enter)(void);
  64
  65 /* Original value of fp_enter from kernel before patched by fpe_init. */
  66 static void (*orig_fp_enter)(void);
  67
  68 /* forward declarations */
  69 extern void nwfpe_enter(void);
  70
  71 #ifdef MODULE
  72 /*
  73  * Return 0 if we can be unloaded.  This can only happen if
  74  * kern_fp_enter is still pointing at nwfpe_enter
  75  */
  76 static int fpe_unload(void)
  77 {
  78   return (kern_fp_enter == nwfpe_enter) ? 0 : 1;
  79 }
  80 #endif
  81
  82 static int __init fpe_init(void)
  83 {
  84   if (sizeof(FPA11) > sizeof(union fp_state)) {
  85     printk(KERN_ERR "nwfpe: bad structure size\n");
  86     return -EINVAL;
  87   }
  88
  89   if (sizeof(FPREG) != 12) {
  90     printk(KERN_ERR "nwfpe: bad register size\n");
  91     return -EINVAL;
  92   }
  93
  94 #ifdef MODULE
  95   if (!mod_member_present(&__this_module, can_unload))
  96     return -EINVAL;
  97   __this_module.can_unload = fpe_unload;
  98 #else
  99   if (fpe_type[0] && strcmp(fpe_type, "nwfpe"))
 100     return 0;
 101 #endif
 102
 103   /* Display title, version and copyright information. */
 104   printk(KERN_WARNING "NetWinder Floating Point Emulator V0.95 "
 105          "(c) 1998-1999 Rebel.com\n");
 106
 107   /* Save pointer to the old FP handler and then patch ourselves in */
 108   orig_fp_enter = kern_fp_enter;
 109   kern_fp_enter = nwfpe_enter;
 110
 111   return 0;
 112 }
 113
 114 static void __exit fpe_exit(void)
 115 {
 116   /* Restore the values we saved earlier. */
 117   kern_fp_enter = orig_fp_enter;
 118 }
 119
 120 /*
 121 ScottB:  November 4, 1998
 122
 123 Moved this function out of softfloat-specialize into fpmodule.c.
 124 This effectively isolates all the changes required for integrating with the
 125 Linux kernel into fpmodule.c.  Porting to NetBSD should only require modifying
 126 fpmodule.c to integrate with the NetBSD kernel (I hope!).
 127
 128 [1/1/99: Not quite true any more unfortunately.  There is Linux-specific
 129 code to access data in user space in some other source files at the
 130 moment (grep for get_user / put_user calls).  --philb]
 131
 132 float_exception_flags is a global variable in SoftFloat.
 133
 134 This function is called by the SoftFloat routines to raise a floating
 135 point exception.  We check the trap enable byte in the FPSR, and raise
 136 a SIGFPE exception if necessary.  If not the relevant bits in the
 137 cumulative exceptions flag byte are set and we return.
 138 */
 139
 140 void float_raise(signed char flags)
 141 {
 142   register unsigned int fpsr, cumulativeTraps;
 143
 144 #ifdef CONFIG_DEBUG_USER
 145   printk(KERN_DEBUG "NWFPE: %s[%d] takes exception %08x at %p from %08x\n",
 146          current->comm, current->pid, flags,
 147          __builtin_return_address(0), GET_USERREG()[15]);
 148 #endif
 149
 150   /* Keep SoftFloat exception flags up to date.  */
 151   float_exception_flags |= flags;
 152
 153   /* Read fpsr and initialize the cumulativeTraps.  */
 154   fpsr = readFPSR();
 155   cumulativeTraps = 0;
 156
 157   /* For each type of exception, the cumulative trap exception bit is only
 158      set if the corresponding trap enable bit is not set.  */
 159   if ((!(fpsr & BIT_IXE)) && (flags & BIT_IXC))
 160      cumulativeTraps |= BIT_IXC;
 161   if ((!(fpsr & BIT_UFE)) && (flags & BIT_UFC))
 162      cumulativeTraps |= BIT_UFC;
 163   if ((!(fpsr & BIT_OFE)) && (flags & BIT_OFC))
 164      cumulativeTraps |= BIT_OFC;
 165   if ((!(fpsr & BIT_DZE)) && (flags & BIT_DZC))
 166      cumulativeTraps |= BIT_DZC;
 167   if ((!(fpsr & BIT_IOE)) && (flags & BIT_IOC))
 168      cumulativeTraps |= BIT_IOC;
 169
 170   /* Set the cumulative exceptions flags.  */
 171   if (cumulativeTraps)
 172     writeFPSR(fpsr | cumulativeTraps);
 173
 174   /* Raise an exception if necessary.  */
 175   if (fpsr & (flags << 16))
 176     fp_send_sig(SIGFPE, current, 1);
 177 }
 178
 179 module_init(fpe_init);
 180 module_exit(fpe_exit);