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/version.h>
28
29#include <linux/errno.h>
30#include <linux/types.h>
31#include <linux/kernel.h>
32#include <linux/signal.h>
33#include <linux/sched.h>
34#include <linux/init.h>
35
36#include "softfloat.h"
37#include "fpopcode.h"
38#include "fpmodule.h"
39#include "fpa11.inl"
40
41/* kernel symbols required for signal handling */
42typedef struct task_struct*	PTASK;
43
44#ifdef MODULE
45void fp_send_sig(unsigned long sig, PTASK p, int priv);
46
47MODULE_AUTHOR("Scott Bambrough <scottb@rebel.com>");
48MODULE_DESCRIPTION("NWFPE floating point emulator");
49
50#else
51#define fp_send_sig	send_sig
52#define kern_fp_enter	fp_enter
53
54extern char fpe_type[];
55#endif
56
57/* kernel function prototypes required */
58void fp_setup(void);
59
60/* external declarations for saved kernel symbols */
61extern void (*kern_fp_enter)(void);
62
63/* Original value of fp_enter from kernel before patched by fpe_init. */
64static void (*orig_fp_enter)(void);
65
66/* forward declarations */
67extern void nwfpe_enter(void);
68
69#ifdef MODULE
70/*
71 * Return 0 if we can be unloaded.  This can only happen if
72 * kern_fp_enter is still pointing at nwfpe_enter
73 */
74static int fpe_unload(void)
75{
76  return (kern_fp_enter == nwfpe_enter) ? 0 : 1;
77}
78#endif
79
80static int __init fpe_init(void)
81{
82  if (sizeof(FPA11) > sizeof(union fp_state)) {
83    printk(KERN_ERR "nwfpe: bad structure size\n");
84    return -EINVAL;
85  }
86
87  if (sizeof(FPREG) != 12) {
88    printk(KERN_ERR "nwfpe: bad register size\n");
89    return -EINVAL;
90  }
91
92#ifdef MODULE
93  if (!mod_member_present(&__this_module, can_unload))
94    return -EINVAL;
95  __this_module.can_unload = fpe_unload;
96#else
97  if (fpe_type[0] && strcmp(fpe_type, "nwfpe"))
98    return 0;
99#endif
100
101  /* Display title, version and copyright information. */
102  printk(KERN_WARNING "NetWinder Floating Point Emulator V0.95 "
103	 "(c) 1998-1999 Rebel.com\n");
104
105  /* Save pointer to the old FP handler and then patch ourselves in */
106  orig_fp_enter = kern_fp_enter;
107  kern_fp_enter = nwfpe_enter;
108
109  return 0;
110}
111
112static void __exit fpe_exit(void)
113{
114  /* Restore the values we saved earlier. */
115  kern_fp_enter = orig_fp_enter;
116}
117
118/*
119ScottB:  November 4, 1998
120
121Moved this function out of softfloat-specialize into fpmodule.c.
122This effectively isolates all the changes required for integrating with the
123Linux kernel into fpmodule.c.  Porting to NetBSD should only require modifying
124fpmodule.c to integrate with the NetBSD kernel (I hope!).
125
126[1/1/99: Not quite true any more unfortunately.  There is Linux-specific
127code to access data in user space in some other source files at the
128moment (grep for get_user / put_user calls).  --philb]
129
130float_exception_flags is a global variable in SoftFloat.
131
132This function is called by the SoftFloat routines to raise a floating
133point exception.  We check the trap enable byte in the FPSR, and raise
134a SIGFPE exception if necessary.  If not the relevant bits in the
135cumulative exceptions flag byte are set and we return.
136*/
137
138void float_raise(signed char flags)
139{
140  register unsigned int fpsr, cumulativeTraps;
141
142#ifdef CONFIG_DEBUG_USER
143  printk(KERN_DEBUG "NWFPE: %s[%d] takes exception %08x at %p from %08x\n",
144	 current->comm, current->pid, flags,
145	 __builtin_return_address(0), GET_USERREG()[15]);
146#endif
147
148  /* Keep SoftFloat exception flags up to date.  */
149  float_exception_flags |= flags;
150
151  /* Read fpsr and initialize the cumulativeTraps.  */
152  fpsr = readFPSR();
153  cumulativeTraps = 0;
154
155  /* For each type of exception, the cumulative trap exception bit is only
156     set if the corresponding trap enable bit is not set.  */
157  if ((!(fpsr & BIT_IXE)) && (flags & BIT_IXC))
158     cumulativeTraps |= BIT_IXC;
159  if ((!(fpsr & BIT_UFE)) && (flags & BIT_UFC))
160     cumulativeTraps |= BIT_UFC;
161  if ((!(fpsr & BIT_OFE)) && (flags & BIT_OFC))
162     cumulativeTraps |= BIT_OFC;
163  if ((!(fpsr & BIT_DZE)) && (flags & BIT_DZC))
164     cumulativeTraps |= BIT_DZC;
165  if ((!(fpsr & BIT_IOE)) && (flags & BIT_IOC))
166     cumulativeTraps |= BIT_IOC;
167
168  /* Set the cumulative exceptions flags.  */
169  if (cumulativeTraps)
170    writeFPSR(fpsr | cumulativeTraps);
171
172  /* Raise an exception if necessary.  */
173  if (fpsr & (flags << 16))
174    fp_send_sig(SIGFPE, current, 1);
175}
176
177module_init(fpe_init);
178module_exit(fpe_exit);
179