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(fp: &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(reg: 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 | |