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 <linux/module.h>
  25 #include <linux/version.h>
  26 #include <linux/config.h>
  27
  28 /* XXX */
  29 #include <linux/types.h>
  30 #include <linux/kernel.h>
  31 #include <linux/signal.h>
  32 #include <linux/sched.h>
  33 #include <linux/init.h>
  34 /* XXX */
  35
  36 #include "softfloat.h"
  37 #include "fpopcode.h"
  38 #include "fpmodule.h"
  39 #include "fpa11.h"
  40 #include "fpa11.inl"
  41
  42 /* external data */
  43 extern FPA11 *fpa11;
  44
  45 /* kernel symbols required for signal handling */
  46 typedef struct task_struct*     PTASK;
  47
  48 #ifdef MODULE
  49 void fp_send_sig(unsigned long sig, PTASK p, int priv);
  50 #if LINUX_VERSION_CODE > 0x20115
  51 MODULE_AUTHOR("Scott Bambrough <scottb@rebel.com>");
  52 MODULE_DESCRIPTION("NWFPE floating point emulator");
  53 #endif
  54
  55 #else
  56 #define fp_send_sig     send_sig
  57 #define kern_fp_enter   fp_enter
  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 /* Address of user registers on the kernel stack. */
  73 unsigned int *userRegisters;
  74
  75 int __init fpe_init(void)
  76 {
  77   if (sizeof(FPA11) > sizeof(union fp_state))
  78     printk(KERN_ERR "nwfpe: bad structure size\n");
  79   else {
  80     /* Display title, version and copyright information. */
  81     printk(KERN_WARNING "NetWinder Floating Point Emulator V0.95 "
  82            "(c) 1998-1999 Rebel.com\n");
  83
  84     /* Save pointer to the old FP handler and then patch ourselves in */
  85     orig_fp_enter = kern_fp_enter;
  86     kern_fp_enter = nwfpe_enter;
  87   }
  88
  89   return 0;
  90 }
  91
  92 void __exit fpe_exit(void)
  93 {
  94   /* Restore the values we saved earlier. */
  95   kern_fp_enter = orig_fp_enter;
  96 }
  97
  98 /*
  99 ScottB:  November 4, 1998
 100
 101 Moved this function out of softfloat-specialize into fpmodule.c.
 102 This effectively isolates all the changes required for integrating with the
 103 Linux kernel into fpmodule.c.  Porting to NetBSD should only require modifying
 104 fpmodule.c to integrate with the NetBSD kernel (I hope!).
 105
 106 [1/1/99: Not quite true any more unfortunately.  There is Linux-specific
 107 code to access data in user space in some other source files at the
 108 moment (grep for get_user / put_user calls).  --philb]
 109
 110 float_exception_flags is a global variable in SoftFloat.
 111
 112 This function is called by the SoftFloat routines to raise a floating
 113 point exception.  We check the trap enable byte in the FPSR, and raise
 114 a SIGFPE exception if necessary.  If not the relevant bits in the
 115 cumulative exceptions flag byte are set and we return.
 116 */
 117
 118 void float_raise(signed char flags)
 119 {
 120   register unsigned int fpsr, cumulativeTraps;
 121
 122 #ifdef CONFIG_DEBUG_USER
 123   printk(KERN_DEBUG "NWFPE: %s[%d] takes exception %08x at %p from %08x\n",
 124          current->comm, current->pid, flags,
 125          __builtin_return_address(0), userRegisters[15]);
 126 #endif
 127
 128   /* Keep SoftFloat exception flags up to date.  */
 129   float_exception_flags |= flags;
 130
 131   /* Read fpsr and initialize the cumulativeTraps.  */
 132   fpsr = readFPSR();
 133   cumulativeTraps = 0;
 134
 135   /* For each type of exception, the cumulative trap exception bit is only
 136      set if the corresponding trap enable bit is not set.  */
 137   if ((!(fpsr & BIT_IXE)) && (flags & BIT_IXC))
 138      cumulativeTraps |= BIT_IXC;
 139   if ((!(fpsr & BIT_UFE)) && (flags & BIT_UFC))
 140      cumulativeTraps |= BIT_UFC;
 141   if ((!(fpsr & BIT_OFE)) && (flags & BIT_OFC))
 142      cumulativeTraps |= BIT_OFC;
 143   if ((!(fpsr & BIT_DZE)) && (flags & BIT_DZC))
 144      cumulativeTraps |= BIT_DZC;
 145   if ((!(fpsr & BIT_IOE)) && (flags & BIT_IOC))
 146      cumulativeTraps |= BIT_IOC;
 147
 148   /* Set the cumulative exceptions flags.  */
 149   if (cumulativeTraps)
 150     writeFPSR(fpsr | cumulativeTraps);
 151
 152   /* Raise an exception if necessary.  */
 153   if (fpsr & (flags << 16))
 154     fp_send_sig(SIGFPE, current, 1);
 155 }
 156
 157 module_init(fpe_init);
 158 module_exit(fpe_exit);