File: /usr/src/linux/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 /* kernel symbols required for signal handling */
43 typedef struct task_struct* PTASK;
44
45 #ifdef MODULE
46 void fp_send_sig(unsigned long sig, PTASK p, int priv);
47 #if LINUX_VERSION_CODE > 0x20115
48 MODULE_AUTHOR("Scott Bambrough <scottb@rebel.com>");
49 MODULE_DESCRIPTION("NWFPE floating point emulator");
50 #endif
51
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
65 /* Original value of fp_enter from kernel before patched by fpe_init. */
66 static void (*orig_fp_enter)(void);
67
68 /* forward declarations */
69 extern void nwfpe_enter(void);
70
71 #ifdef MODULE
72 /*
73 * Return 0 if we can be unloaded. This can only happen if
74 * kern_fp_enter is still pointing at nwfpe_enter
75 */
76 static int fpe_unload(void)
77 {
78 return (kern_fp_enter == nwfpe_enter) ? 0 : 1;
79 }
80 #endif
81
82 static int __init fpe_init(void)
83 {
84 if (sizeof(FPA11) > sizeof(union fp_state)) {
85 printk(KERN_ERR "nwfpe: bad structure size\n");
86 return -EINVAL;
87 }
88
89 #ifdef MODULE
90 if (!mod_member_present(&__this_module, can_unload))
91 return -EINVAL;
92 __this_module.can_unload = fpe_unload;
93 #else
94 if (fpe_type[0] && strcmp(fpe_type, "nwfpe"))
95 return 0;
96 #endif
97
98 /* Display title, version and copyright information. */
99 printk(KERN_WARNING "NetWinder Floating Point Emulator V0.95 "
100 "(c) 1998-1999 Rebel.com\n");
101
102 /* Save pointer to the old FP handler and then patch ourselves in */
103 orig_fp_enter = kern_fp_enter;
104 kern_fp_enter = nwfpe_enter;
105
106 return 0;
107 }
108
109 static void __exit fpe_exit(void)
110 {
111 /* Restore the values we saved earlier. */
112 kern_fp_enter = orig_fp_enter;
113 }
114
115 /*
116 ScottB: November 4, 1998
117
118 Moved this function out of softfloat-specialize into fpmodule.c.
119 This effectively isolates all the changes required for integrating with the
120 Linux kernel into fpmodule.c. Porting to NetBSD should only require modifying
121 fpmodule.c to integrate with the NetBSD kernel (I hope!).
122
123 [1/1/99: Not quite true any more unfortunately. There is Linux-specific
124 code to access data in user space in some other source files at the
125 moment (grep for get_user / put_user calls). --philb]
126
127 float_exception_flags is a global variable in SoftFloat.
128
129 This function is called by the SoftFloat routines to raise a floating
130 point exception. We check the trap enable byte in the FPSR, and raise
131 a SIGFPE exception if necessary. If not the relevant bits in the
132 cumulative exceptions flag byte are set and we return.
133 */
134
135 void float_raise(signed char flags)
136 {
137 register unsigned int fpsr, cumulativeTraps;
138
139 #ifdef CONFIG_DEBUG_USER
140 printk(KERN_DEBUG "NWFPE: %s[%d] takes exception %08x at %p from %08x\n",
141 current->comm, current->pid, flags,
142 __builtin_return_address(0), GET_USERREG()[15]);
143 #endif
144
145 /* Keep SoftFloat exception flags up to date. */
146 float_exception_flags |= flags;
147
148 /* Read fpsr and initialize the cumulativeTraps. */
149 fpsr = readFPSR();
150 cumulativeTraps = 0;
151
152 /* For each type of exception, the cumulative trap exception bit is only
153 set if the corresponding trap enable bit is not set. */
154 if ((!(fpsr & BIT_IXE)) && (flags & BIT_IXC))
155 cumulativeTraps |= BIT_IXC;
156 if ((!(fpsr & BIT_UFE)) && (flags & BIT_UFC))
157 cumulativeTraps |= BIT_UFC;
158 if ((!(fpsr & BIT_OFE)) && (flags & BIT_OFC))
159 cumulativeTraps |= BIT_OFC;
160 if ((!(fpsr & BIT_DZE)) && (flags & BIT_DZC))
161 cumulativeTraps |= BIT_DZC;
162 if ((!(fpsr & BIT_IOE)) && (flags & BIT_IOC))
163 cumulativeTraps |= BIT_IOC;
164
165 /* Set the cumulative exceptions flags. */
166 if (cumulativeTraps)
167 writeFPSR(fpsr | cumulativeTraps);
168
169 /* Raise an exception if necessary. */
170 if (fpsr & (flags << 16))
171 fp_send_sig(SIGFPE, current, 1);
172 }
173
174 module_init(fpe_init);
175 module_exit(fpe_exit);
176