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