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 
nwfpe_notify(struct notifier_block * self,unsigned long cmd,void * v)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 
fpe_init(void)86 static int __init fpe_init(void)
87 {
88 	if (sizeof(FPA11) > sizeof(union fp_state)) {
89 		printk(KERN_ERR "nwfpe: bad structure size\n");
90 		return -EINVAL;
91 	}
92 
93 	if (sizeof(FPREG) != 12) {
94 		printk(KERN_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 	printk(KERN_WARNING "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 
fpe_exit(void)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 
float_raise(signed char flags)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 %p 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