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/config.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 #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 /* 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 extern void (*fp_init)(union fp_state *);
  65
  66 /* Original value of fp_enter from kernel before patched by fpe_init. */
  67 static void (*orig_fp_enter)(void);
  68 static void (*orig_fp_init)(union fp_state *);
  69
  70 /* forward declarations */
  71 extern void nwfpe_enter(void);
  72
  73 static int __init fpe_init(void)
  74 {
  75         if (sizeof(FPA11) > sizeof(union fp_state)) {
  76                 printk(KERN_ERR "nwfpe: bad structure size\n");
  77                 return -EINVAL;
  78         }
  79
  80         if (sizeof(FPREG) != 12) {
  81                 printk(KERN_ERR "nwfpe: bad register size\n");
  82                 return -EINVAL;
  83         }
  84         if (fpe_type[0] && strcmp(fpe_type, "nwfpe"))
  85                 return 0;
  86
  87         /* Display title, version and copyright information. */
  88         printk(KERN_WARNING "NetWinder Floating Point Emulator V0.97 ("
  89                NWFPE_BITS " precision)\n");
  90
  91         /* Save pointer to the old FP handler and then patch ourselves in */
  92         orig_fp_enter = kern_fp_enter;
  93         orig_fp_init = fp_init;
  94         kern_fp_enter = nwfpe_enter;
  95         fp_init = nwfpe_init_fpa;
  96
  97         return 0;
  98 }
  99
 100 static void __exit fpe_exit(void)
 101 {
 102         /* Restore the values we saved earlier. */
 103         kern_fp_enter = orig_fp_enter;
 104         fp_init = orig_fp_init;
 105 }
 106
 107 /*
 108 ScottB:  November 4, 1998
 109
 110 Moved this function out of softfloat-specialize into fpmodule.c.
 111 This effectively isolates all the changes required for integrating with the
 112 Linux kernel into fpmodule.c.  Porting to NetBSD should only require modifying
 113 fpmodule.c to integrate with the NetBSD kernel (I hope!).
 114
 115 [1/1/99: Not quite true any more unfortunately.  There is Linux-specific
 116 code to access data in user space in some other source files at the
 117 moment (grep for get_user / put_user calls).  --philb]
 118
 119 float_exception_flags is a global variable in SoftFloat.
 120
 121 This function is called by the SoftFloat routines to raise a floating
 122 point exception.  We check the trap enable byte in the FPSR, and raise
 123 a SIGFPE exception if necessary.  If not the relevant bits in the
 124 cumulative exceptions flag byte are set and we return.
 125 */
 126
 127 void float_raise(signed char flags)
 128 {
 129         register unsigned int fpsr, cumulativeTraps;
 130
 131 #ifdef CONFIG_DEBUG_USER
 132         printk(KERN_DEBUG
 133                "NWFPE: %s[%d] takes exception %08x at %p from %08lx\n",
 134                current->comm, current->pid, flags,
 135                __builtin_return_address(0), GET_USERREG()->ARM_pc);
 136 #endif
 137
 138         /* Keep SoftFloat exception flags up to date.  */
 139         float_exception_flags |= flags;
 140
 141         /* Read fpsr and initialize the cumulativeTraps.  */
 142         fpsr = readFPSR();
 143         cumulativeTraps = 0;
 144
 145         /* For each type of exception, the cumulative trap exception bit is only
 146            set if the corresponding trap enable bit is not set.  */
 147         if ((!(fpsr & BIT_IXE)) && (flags & BIT_IXC))
 148                 cumulativeTraps |= BIT_IXC;
 149         if ((!(fpsr & BIT_UFE)) && (flags & BIT_UFC))
 150                 cumulativeTraps |= BIT_UFC;
 151         if ((!(fpsr & BIT_OFE)) && (flags & BIT_OFC))
 152                 cumulativeTraps |= BIT_OFC;
 153         if ((!(fpsr & BIT_DZE)) && (flags & BIT_DZC))
 154                 cumulativeTraps |= BIT_DZC;
 155         if ((!(fpsr & BIT_IOE)) && (flags & BIT_IOC))
 156                 cumulativeTraps |= BIT_IOC;
 157
 158         /* Set the cumulative exceptions flags.  */
 159         if (cumulativeTraps)
 160                 writeFPSR(fpsr | cumulativeTraps);
 161
 162         /* Raise an exception if necessary.  */
 163         if (fpsr & (flags << 16))
 164                 fp_send_sig(SIGFPE, current, 1);
 165 }
 166
 167 module_init(fpe_init);
 168 module_exit(fpe_exit);
 169
 170 MODULE_AUTHOR("Scott Bambrough <scottb@rebel.com>");
 171 MODULE_DESCRIPTION("NWFPE floating point emulator (" NWFPE_BITS " precision)");
 172 MODULE_LICENSE("GPL");