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