xref: /openbmc/linux/arch/arm/nwfpe/fpmodule.c (revision 74ba9207)
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 
nwfpe_notify(struct notifier_block * self,unsigned long cmd,void * v)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 
fpe_init(void)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 
fpe_exit(void)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 
float_raise(signed char flags)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