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 %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