1 // SPDX-License-Identifier: GPL-2.0-or-later
2
3 /*
4 NetWinder Floating Point Emulator
5 (c) Rebel.com, 1998-1999
6 (c) Philip Blundell, 1998-1999
7
8 Direct questions, comments to Scott Bambrough <scottb@netwinder.org>
9
10 */
11
12 #include "fpa11.h"
13
14 #include <linux/module.h>
15 #include <linux/moduleparam.h>
16
17 /* XXX */
18 #include <linux/errno.h>
19 #include <linux/types.h>
20 #include <linux/kernel.h>
21 #include <linux/signal.h>
22 #include <linux/sched/signal.h>
23 #include <linux/init.h>
24
25 #include <asm/thread_notify.h>
26
27 #include "softfloat.h"
28 #include "fpopcode.h"
29 #include "fpmodule.h"
30 #include "fpa11.inl"
31
32 /* kernel symbols required for signal handling */
33 #ifdef CONFIG_FPE_NWFPE_XP
34 #define NWFPE_BITS "extended"
35 #else
36 #define NWFPE_BITS "double"
37 #endif
38
39 #ifdef MODULE
40 void fp_send_sig(unsigned long sig, struct task_struct *p, int priv);
41 #else
42 #define fp_send_sig send_sig
43 #define kern_fp_enter fp_enter
44
45 extern char fpe_type[];
46 #endif
47
48 static int nwfpe_notify(struct notifier_block *self, unsigned long cmd, void *v)
49 {
50 struct thread_info *thread = v;
51
52 if (cmd == THREAD_NOTIFY_FLUSH)
53 nwfpe_init_fpa(&thread->fpstate);
54
55 return NOTIFY_DONE;
56 }
57
58 static struct notifier_block nwfpe_notifier_block = {
59 .notifier_call = nwfpe_notify,
60 };
61
62 /* kernel function prototypes required */
63 void fp_setup(void);
64
65 /* external declarations for saved kernel symbols */
66 extern void (*kern_fp_enter)(void);
67
68 /* Original value of fp_enter from kernel before patched by fpe_init. */
69 static void (*orig_fp_enter)(void);
70
71 /* forward declarations */
72 extern void nwfpe_enter(void);
73
74 static int __init fpe_init(void)
75 {
76 if (sizeof(FPA11) > sizeof(union fp_state)) {
77 pr_err("nwfpe: bad structure size\n");
78 return -EINVAL;
79 }
80
81 if (sizeof(FPREG) != 12) {
82 pr_err("nwfpe: bad register size\n");
83 return -EINVAL;
84 }
85 if (fpe_type[0] && strcmp(fpe_type, "nwfpe"))
86 return 0;
87
88 /* Display title, version and copyright information. */
89 pr_info("NetWinder Floating Point Emulator V0.97 ("
90 NWFPE_BITS " precision)\n");
91
92 thread_register_notifier(&nwfpe_notifier_block);
93
94 /* Save pointer to the old FP handler and then patch ourselves in */
95 orig_fp_enter = kern_fp_enter;
96 kern_fp_enter = nwfpe_enter;
97
98 return 0;
99 }
100
101 static void __exit fpe_exit(void)
102 {
103 thread_unregister_notifier(&nwfpe_notifier_block);
104 /* Restore the values we saved earlier. */
105 kern_fp_enter = orig_fp_enter;
106 }
107
108 /*
109 ScottB: November 4, 1998
110
111 Moved this function out of softfloat-specialize into fpmodule.c.
112 This effectively isolates all the changes required for integrating with the
113 Linux kernel into fpmodule.c. Porting to NetBSD should only require modifying
114 fpmodule.c to integrate with the NetBSD kernel (I hope!).
115
116 [1/1/99: Not quite true any more unfortunately. There is Linux-specific
117 code to access data in user space in some other source files at the
118 moment (grep for get_user / put_user calls). --philb]
119
120 This function is called by the SoftFloat routines to raise a floating
121 point exception. We check the trap enable byte in the FPSR, and raise
122 a SIGFPE exception if necessary. If not the relevant bits in the
123 cumulative exceptions flag byte are set and we return.
124 */
125
126 #ifdef CONFIG_DEBUG_USER
127 /* By default, ignore inexact errors as there are far too many of them to log */
128 static int debug = ~BIT_IXC;
129 #endif
130
131 void float_raise(signed char flags)
132 {
133 register unsigned int fpsr, cumulativeTraps;
134
135 #ifdef CONFIG_DEBUG_USER
136 if (flags & debug)
137 printk(KERN_DEBUG
138 "NWFPE: %s[%d] takes exception %08x at %ps from %08lx\n",
139 current->comm, current->pid, flags,
140 __builtin_return_address(0), GET_USERREG()->ARM_pc);
141 #endif
142
143 /* Read fpsr and initialize the cumulativeTraps. */
144 fpsr = readFPSR();
145 cumulativeTraps = 0;
146
147 /* For each type of exception, the cumulative trap exception bit is only
148 set if the corresponding trap enable bit is not set. */
149 if ((!(fpsr & BIT_IXE)) && (flags & BIT_IXC))
150 cumulativeTraps |= BIT_IXC;
151 if ((!(fpsr & BIT_UFE)) && (flags & BIT_UFC))
152 cumulativeTraps |= BIT_UFC;
153 if ((!(fpsr & BIT_OFE)) && (flags & BIT_OFC))
154 cumulativeTraps |= BIT_OFC;
155 if ((!(fpsr & BIT_DZE)) && (flags & BIT_DZC))
156 cumulativeTraps |= BIT_DZC;
157 if ((!(fpsr & BIT_IOE)) && (flags & BIT_IOC))
158 cumulativeTraps |= BIT_IOC;
159
160 /* Set the cumulative exceptions flags. */
161 if (cumulativeTraps)
162 writeFPSR(fpsr | cumulativeTraps);
163
164 /* Raise an exception if necessary. */
165 if (fpsr & (flags << 16))
166 fp_send_sig(SIGFPE, current, 1);
167 }
168
169 module_init(fpe_init);
170 module_exit(fpe_exit);
171
172 MODULE_AUTHOR("Scott Bambrough <scottb@rebel.com>");
173 MODULE_DESCRIPTION("NWFPE floating point emulator (" NWFPE_BITS " precision)");
174 MODULE_LICENSE("GPL");
175
176 #ifdef CONFIG_DEBUG_USER
177 module_param(debug, int, 0644);
178 #endif
179
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