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 #include <linux/config.h>
  29
  30 /* XXX */
  31 #include <linux/errno.h>
  32 #include <linux/types.h>
  33 #include <linux/kernel.h>
  34 #include <linux/signal.h>
  35 #include <linux/sched.h>
  36 #include <linux/init.h>
  37 /* XXX */
  38
  39 #include "softfloat.h"
  40 #include "fpopcode.h"
  41 #include "fpmodule.h"
  42 #include "fpa11.inl"
  43
  44 /* kernel symbols required for signal handling */
  45 typedef struct task_struct*     PTASK;
  46
  47 #ifdef MODULE
  48 void fp_send_sig(unsigned long sig, PTASK p, int priv);
  49
  50 MODULE_AUTHOR("Scott Bambrough <scottb@rebel.com>");
  51 MODULE_DESCRIPTION("NWFPE floating point emulator");
  52
  53 #else
  54 #define fp_send_sig     send_sig
  55 #define kern_fp_enter   fp_enter
  56
  57 extern char fpe_type[];
  58 #endif
  59
  60 /* kernel function prototypes required */
  61 void fp_setup(void);
  62
  63 /* external declarations for saved kernel symbols */
  64 extern void (*kern_fp_enter)(void);
  65
  66 /* Original value of fp_enter from kernel before patched by fpe_init. */
  67 static void (*orig_fp_enter)(void);
  68
  69 /* forward declarations */
  70 extern void nwfpe_enter(void);
  71
  72 #ifdef MODULE
  73 /*
  74  * Return 0 if we can be unloaded.  This can only happen if
  75  * kern_fp_enter is still pointing at nwfpe_enter
  76  */
  77 static int fpe_unload(void)
  78 {
  79   return (kern_fp_enter == nwfpe_enter) ? 0 : 1;
  80 }
  81 #endif
  82
  83 static int __init fpe_init(void)
  84 {
  85   if (sizeof(FPA11) > sizeof(union fp_state)) {
  86     printk(KERN_ERR "nwfpe: bad structure size\n");
  87     return -EINVAL;
  88   }
  89
  90   if (sizeof(FPREG) != 12) {
  91     printk(KERN_ERR "nwfpe: bad register size\n");
  92     return -EINVAL;
  93   }
  94
  95 #ifdef MODULE
  96   if (!mod_member_present(&__this_module, can_unload))
  97     return -EINVAL;
  98   __this_module.can_unload = fpe_unload;
  99 #else
 100   if (fpe_type[0] && strcmp(fpe_type, "nwfpe"))
 101     return 0;
 102 #endif
 103
 104   /* Display title, version and copyright information. */
 105   printk(KERN_WARNING "NetWinder Floating Point Emulator V0.95 "
 106          "(c) 1998-1999 Rebel.com\n");
 107
 108   /* Save pointer to the old FP handler and then patch ourselves in */
 109   orig_fp_enter = kern_fp_enter;
 110   kern_fp_enter = nwfpe_enter;
 111
 112   return 0;
 113 }
 114
 115 static void __exit fpe_exit(void)
 116 {
 117   /* Restore the values we saved earlier. */
 118   kern_fp_enter = orig_fp_enter;
 119 }
 120
 121 /*
 122 ScottB:  November 4, 1998
 123
 124 Moved this function out of softfloat-specialize into fpmodule.c.
 125 This effectively isolates all the changes required for integrating with the
 126 Linux kernel into fpmodule.c.  Porting to NetBSD should only require modifying
 127 fpmodule.c to integrate with the NetBSD kernel (I hope!).
 128
 129 [1/1/99: Not quite true any more unfortunately.  There is Linux-specific
 130 code to access data in user space in some other source files at the
 131 moment (grep for get_user / put_user calls).  --philb]
 132
 133 float_exception_flags is a global variable in SoftFloat.
 134
 135 This function is called by the SoftFloat routines to raise a floating
 136 point exception.  We check the trap enable byte in the FPSR, and raise
 137 a SIGFPE exception if necessary.  If not the relevant bits in the
 138 cumulative exceptions flag byte are set and we return.
 139 */
 140
 141 void float_raise(signed char flags)
 142 {
 143   register unsigned int fpsr, cumulativeTraps;
 144
 145 #ifdef CONFIG_DEBUG_USER
 146   printk(KERN_DEBUG "NWFPE: %s[%d] takes exception %08x at %p from %08x\n",
 147          current->comm, current->pid, flags,
 148          __builtin_return_address(0), GET_USERREG()[15]);
 149 #endif
 150
 151   /* Keep SoftFloat exception flags up to date.  */
 152   float_exception_flags |= flags;
 153
 154   /* Read fpsr and initialize the cumulativeTraps.  */
 155   fpsr = readFPSR();
 156   cumulativeTraps = 0;
 157
 158   /* For each type of exception, the cumulative trap exception bit is only
 159      set if the corresponding trap enable bit is not set.  */
 160   if ((!(fpsr & BIT_IXE)) && (flags & BIT_IXC))
 161      cumulativeTraps |= BIT_IXC;
 162   if ((!(fpsr & BIT_UFE)) && (flags & BIT_UFC))
 163      cumulativeTraps |= BIT_UFC;
 164   if ((!(fpsr & BIT_OFE)) && (flags & BIT_OFC))
 165      cumulativeTraps |= BIT_OFC;
 166   if ((!(fpsr & BIT_DZE)) && (flags & BIT_DZC))
 167      cumulativeTraps |= BIT_DZC;
 168   if ((!(fpsr & BIT_IOE)) && (flags & BIT_IOC))
 169      cumulativeTraps |= BIT_IOC;
 170
 171   /* Set the cumulative exceptions flags.  */
 172   if (cumulativeTraps)
 173     writeFPSR(fpsr | cumulativeTraps);
 174
 175   /* Raise an exception if necessary.  */
 176   if (fpsr & (flags << 16))
 177     fp_send_sig(SIGFPE, current, 1);
 178 }
 179
 180 module_init(fpe_init);
 181 module_exit(fpe_exit);