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Linux/arch/arm/nwfpe/fpmodule.c

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  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/moduleparam.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 
 37 #include <asm/thread_notify.h>
 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 static int nwfpe_notify(struct notifier_block *self, unsigned long cmd, void *v)
 61 {
 62         struct thread_info *thread = v;
 63 
 64         if (cmd == THREAD_NOTIFY_FLUSH)
 65                 nwfpe_init_fpa(&thread->fpstate);
 66 
 67         return NOTIFY_DONE;
 68 }
 69 
 70 static struct notifier_block nwfpe_notifier_block = {
 71         .notifier_call = nwfpe_notify,
 72 };
 73 
 74 /* kernel function prototypes required */
 75 void fp_setup(void);
 76 
 77 /* external declarations for saved kernel symbols */
 78 extern void (*kern_fp_enter)(void);
 79 
 80 /* Original value of fp_enter from kernel before patched by fpe_init. */
 81 static void (*orig_fp_enter)(void);
 82 
 83 /* forward declarations */
 84 extern void nwfpe_enter(void);
 85 
 86 static int __init fpe_init(void)
 87 {
 88         if (sizeof(FPA11) > sizeof(union fp_state)) {
 89                 pr_err("nwfpe: bad structure size\n");
 90                 return -EINVAL;
 91         }
 92 
 93         if (sizeof(FPREG) != 12) {
 94                 pr_err("nwfpe: bad register size\n");
 95                 return -EINVAL;
 96         }
 97         if (fpe_type[0] && strcmp(fpe_type, "nwfpe"))
 98                 return 0;
 99 
100         /* Display title, version and copyright information. */
101         pr_info("NetWinder Floating Point Emulator V0.97 ("
102                 NWFPE_BITS " precision)\n");
103 
104         thread_register_notifier(&nwfpe_notifier_block);
105 
106         /* Save pointer to the old FP handler and then patch ourselves in */
107         orig_fp_enter = kern_fp_enter;
108         kern_fp_enter = nwfpe_enter;
109 
110         return 0;
111 }
112 
113 static void __exit fpe_exit(void)
114 {
115         thread_unregister_notifier(&nwfpe_notifier_block);
116         /* Restore the values we saved earlier. */
117         kern_fp_enter = orig_fp_enter;
118 }
119 
120 /*
121 ScottB:  November 4, 1998
122 
123 Moved this function out of softfloat-specialize into fpmodule.c.
124 This effectively isolates all the changes required for integrating with the
125 Linux kernel into fpmodule.c.  Porting to NetBSD should only require modifying
126 fpmodule.c to integrate with the NetBSD kernel (I hope!).
127 
128 [1/1/99: Not quite true any more unfortunately.  There is Linux-specific
129 code to access data in user space in some other source files at the 
130 moment (grep for get_user / put_user calls).  --philb]
131 
132 This function is called by the SoftFloat routines to raise a floating
133 point exception.  We check the trap enable byte in the FPSR, and raise
134 a SIGFPE exception if necessary.  If not the relevant bits in the 
135 cumulative exceptions flag byte are set and we return.
136 */
137 
138 #ifdef CONFIG_DEBUG_USER
139 /* By default, ignore inexact errors as there are far too many of them to log */
140 static int debug = ~BIT_IXC;
141 #endif
142 
143 void float_raise(signed char flags)
144 {
145         register unsigned int fpsr, cumulativeTraps;
146 
147 #ifdef CONFIG_DEBUG_USER
148         if (flags & debug)
149                 printk(KERN_DEBUG
150                        "NWFPE: %s[%d] takes exception %08x at %pf from %08lx\n",
151                        current->comm, current->pid, flags,
152                        __builtin_return_address(0), GET_USERREG()->ARM_pc);
153 #endif
154 
155         /* Read fpsr and initialize the cumulativeTraps.  */
156         fpsr = readFPSR();
157         cumulativeTraps = 0;
158 
159         /* For each type of exception, the cumulative trap exception bit is only
160            set if the corresponding trap enable bit is not set.  */
161         if ((!(fpsr & BIT_IXE)) && (flags & BIT_IXC))
162                 cumulativeTraps |= BIT_IXC;
163         if ((!(fpsr & BIT_UFE)) && (flags & BIT_UFC))
164                 cumulativeTraps |= BIT_UFC;
165         if ((!(fpsr & BIT_OFE)) && (flags & BIT_OFC))
166                 cumulativeTraps |= BIT_OFC;
167         if ((!(fpsr & BIT_DZE)) && (flags & BIT_DZC))
168                 cumulativeTraps |= BIT_DZC;
169         if ((!(fpsr & BIT_IOE)) && (flags & BIT_IOC))
170                 cumulativeTraps |= BIT_IOC;
171 
172         /* Set the cumulative exceptions flags.  */
173         if (cumulativeTraps)
174                 writeFPSR(fpsr | cumulativeTraps);
175 
176         /* Raise an exception if necessary.  */
177         if (fpsr & (flags << 16))
178                 fp_send_sig(SIGFPE, current, 1);
179 }
180 
181 module_init(fpe_init);
182 module_exit(fpe_exit);
183 
184 MODULE_AUTHOR("Scott Bambrough <scottb@rebel.com>");
185 MODULE_DESCRIPTION("NWFPE floating point emulator (" NWFPE_BITS " precision)");
186 MODULE_LICENSE("GPL");
187 
188 #ifdef CONFIG_DEBUG_USER
189 module_param(debug, int, 0644);
190 #endif
191 

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