aboutsummaryrefslogtreecommitdiffstats
path: root/arch/arm/vfp/vfpmodule.c
blob: 9d265d5e748cc8b7b77715fda22220f1912c4f4d (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
/*
 *  linux/arch/arm/vfp/vfpmodule.c
 *
 *  Copyright (C) 2004 ARM Limited.
 *  Written by Deep Blue Solutions Limited.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */
#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/init.h>

#include <asm/thread_notify.h>
#include <asm/vfp.h>

#include "vfpinstr.h"
#include "vfp.h"

/*
 * Our undef handlers (in entry.S)
 */
void vfp_testing_entry(void);
void vfp_support_entry(void);

void (*vfp_vector)(void) = vfp_testing_entry;
union vfp_state *last_VFP_context;

/*
 * Dual-use variable.
 * Used in startup: set to non-zero if VFP checks fail
 * After startup, holds VFP architecture
 */
unsigned int VFP_arch;

static int vfp_notifier(struct notifier_block *self, unsigned long cmd, void *v)
{
	struct thread_info *thread = v;
	union vfp_state *vfp = &thread->vfpstate;

	switch (cmd) {
	case THREAD_NOTIFY_FLUSH:
		/*
		 * Per-thread VFP initialisation.
		 */
		memset(vfp, 0, sizeof(union vfp_state));

		vfp->hard.fpexc = FPEXC_ENABLE;
		vfp->hard.fpscr = FPSCR_ROUND_NEAREST;

		/*
		 * Disable VFP to ensure we initialise it first.
		 */
		fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_ENABLE);

		/*
		 * FALLTHROUGH: Ensure we don't try to overwrite our newly
		 * initialised state information on the first fault.
		 */

	case THREAD_NOTIFY_RELEASE:
		/*
		 * Per-thread VFP cleanup.
		 */
		if (last_VFP_context == vfp)
			last_VFP_context = NULL;
		break;

	case THREAD_NOTIFY_SWITCH:
		/*
		 * Always disable VFP so we can lazily save/restore the
		 * old state.
		 */
		fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_ENABLE);
		break;
	}

	return NOTIFY_DONE;
}

static struct notifier_block vfp_notifier_block = {
	.notifier_call	= vfp_notifier,
};

/*
 * Raise a SIGFPE for the current process.
 * sicode describes the signal being raised.
 */
void vfp_raise_sigfpe(unsigned int sicode, struct pt_regs *regs)
{
	siginfo_t info;

	memset(&info, 0, sizeof(info));

	info.si_signo = SIGFPE;
	info.si_code = sicode;
	info.si_addr = (void *)(instruction_pointer(regs) - 4);

	/*
	 * This is the same as NWFPE, because it's not clear what
	 * this is used for
	 */
	current->thread.error_code = 0;
	current->thread.trap_no = 6;

	send_sig_info(SIGFPE, &info, current);
}

static void vfp_panic(char *reason)
{
	int i;

	printk(KERN_ERR "VFP: Error: %s\n", reason);
	printk(KERN_ERR "VFP: EXC 0x%08x SCR 0x%08x INST 0x%08x\n",
		fmrx(FPEXC), fmrx(FPSCR), fmrx(FPINST));
	for (i = 0; i < 32; i += 2)
		printk(KERN_ERR "VFP: s%2u: 0x%08x s%2u: 0x%08x\n",
		       i, vfp_get_float(i), i+1, vfp_get_float(i+1));
}

/*
 * Process bitmask of exception conditions.
 */
static void vfp_raise_exceptions(u32 exceptions, u32 inst, u32 fpscr, struct pt_regs *regs)
{
	int si_code = 0;

	pr_debug("VFP: raising exceptions %08x\n", exceptions);

	if (exceptions == (u32)-1) {
		vfp_panic("unhandled bounce");
		vfp_raise_sigfpe(0, regs);
		return;
	}

	/*
	 * If any of the status flags are set, update the FPSCR.
	 * Comparison instructions always return at least one of
	 * these flags set.
	 */
	if (exceptions & (FPSCR_N|FPSCR_Z|FPSCR_C|FPSCR_V))
		fpscr &= ~(FPSCR_N|FPSCR_Z|FPSCR_C|FPSCR_V);

	fpscr |= exceptions;

	fmxr(FPSCR, fpscr);

#define RAISE(stat,en,sig)				\
	if (exceptions & stat && fpscr & en)		\
		si_code = sig;

	/*
	 * These are arranged in priority order, least to highest.
	 */
	RAISE(FPSCR_IXC, FPSCR_IXE, FPE_FLTRES);
	RAISE(FPSCR_UFC, FPSCR_UFE, FPE_FLTUND);
	RAISE(FPSCR_OFC, FPSCR_OFE, FPE_FLTOVF);
	RAISE(FPSCR_IOC, FPSCR_IOE, FPE_FLTINV);

	if (si_code)
		vfp_raise_sigfpe(si_code, regs);
}

/*
 * Emulate a VFP instruction.
 */
static u32 vfp_emulate_instruction(u32 inst, u32 fpscr, struct pt_regs *regs)
{
	u32 exceptions = (u32)-1;

	pr_debug("VFP: emulate: INST=0x%08x SCR=0x%08x\n", inst, fpscr);

	if (INST_CPRTDO(inst)) {
		if (!INST_CPRT(inst)) {
			/*
			 * CPDO
			 */
			if (vfp_single(inst)) {
				exceptions = vfp_single_cpdo(inst, fpscr);
			} else {
				exceptions = vfp_double_cpdo(inst, fpscr);
			}
		} else {
			/*
			 * A CPRT instruction can not appear in FPINST2, nor
			 * can it cause an exception.  Therefore, we do not
			 * have to emulate it.
			 */
		}
	} else {
		/*
		 * A CPDT instruction can not appear in FPINST2, nor can
		 * it cause an exception.  Therefore, we do not have to
		 * emulate it.
		 */
	}
	return exceptions & ~VFP_NAN_FLAG;
}

/*
 * Package up a bounce condition.
 */
void VFP9_bounce(u32 trigger, u32 fpexc, struct pt_regs *regs)
{
	u32 fpscr, orig_fpscr, exceptions, inst;

	pr_debug("VFP: bounce: trigger %08x fpexc %08x\n", trigger, fpexc);

	/*
	 * Enable access to the VFP so we can handle the bounce.
	 */
	fmxr(FPEXC, fpexc & ~(FPEXC_EXCEPTION|FPEXC_INV|FPEXC_UFC|FPEXC_IOC));

	orig_fpscr = fpscr = fmrx(FPSCR);

	/*
	 * If we are running with inexact exceptions enabled, we need to
	 * emulate the trigger instruction.  Note that as we're emulating
	 * the trigger instruction, we need to increment PC.
	 */
	if (fpscr & FPSCR_IXE) {
		regs->ARM_pc += 4;
		goto emulate;
	}

	barrier();

	/*
	 * Modify fpscr to indicate the number of iterations remaining
	 */
	if (fpexc & FPEXC_EXCEPTION) {
		u32 len;

		len = fpexc + (1 << FPEXC_LENGTH_BIT);

		fpscr &= ~FPSCR_LENGTH_MASK;
		fpscr |= (len & FPEXC_LENGTH_MASK) << (FPSCR_LENGTH_BIT - FPEXC_LENGTH_BIT);
	}

	/*
	 * Handle the first FP instruction.  We used to take note of the
	 * FPEXC bounce reason, but this appears to be unreliable.
	 * Emulate the bounced instruction instead.
	 */
	inst = fmrx(FPINST);
	exceptions = vfp_emulate_instruction(inst, fpscr, regs);
	if (exceptions)
		vfp_raise_exceptions(exceptions, inst, orig_fpscr, regs);

	/*
	 * If there isn't a second FP instruction, exit now.
	 */
	if (!(fpexc & FPEXC_FPV2))
		return;

	/*
	 * The barrier() here prevents fpinst2 being read
	 * before the condition above.
	 */
	barrier();
	trigger = fmrx(FPINST2);
	orig_fpscr = fpscr = fmrx(FPSCR);

 emulate:
	exceptions = vfp_emulate_instruction(trigger, fpscr, regs);
	if (exceptions)
		vfp_raise_exceptions(exceptions, trigger, orig_fpscr, regs);
}
 
/*
 * VFP support code initialisation.
 */
static int __init vfp_init(void)
{
	unsigned int vfpsid;

	/*
	 * First check that there is a VFP that we can use.
	 * The handler is already setup to just log calls, so
	 * we just need to read the VFPSID register.
	 */
	vfpsid = fmrx(FPSID);

	printk(KERN_INFO "VFP support v0.3: ");
	if (VFP_arch) {
		printk("not present\n");
	} else if (vfpsid & FPSID_NODOUBLE) {
		printk("no double precision support\n");
	} else {
		VFP_arch = (vfpsid & FPSID_ARCH_MASK) >> FPSID_ARCH_BIT;  /* Extract the architecture version */
		printk("implementor %02x architecture %d part %02x variant %x rev %x\n",
			(vfpsid & FPSID_IMPLEMENTER_MASK) >> FPSID_IMPLEMENTER_BIT,
			(vfpsid & FPSID_ARCH_MASK) >> FPSID_ARCH_BIT,
			(vfpsid & FPSID_PART_MASK) >> FPSID_PART_BIT,
			(vfpsid & FPSID_VARIANT_MASK) >> FPSID_VARIANT_BIT,
			(vfpsid & FPSID_REV_MASK) >> FPSID_REV_BIT);
		vfp_vector = vfp_support_entry;

		thread_register_notifier(&vfp_notifier_block);
	}
	return 0;
}

late_initcall(vfp_init);