summaryrefslogtreecommitdiffstats
path: root/arch/arm/vfp/vfpmodule.c
blob: 7e1239041b39ed5e827266945b00334dfcf4ccf6 (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
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
/*
 *  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_null_entry(void);

void (*vfp_vector)(void) = vfp_null_entry;
union vfp_state *last_VFP_context[NR_CPUS];

/*
 * 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;
	__u32 cpu = thread->cpu;

	if (likely(cmd == THREAD_NOTIFY_SWITCH)) {
		u32 fpexc = fmrx(FPEXC);

#ifdef CONFIG_SMP
		/*
		 * On SMP, if VFP is enabled, save the old state in
		 * case the thread migrates to a different CPU. The
		 * restoring is done lazily.
		 */
		if ((fpexc & FPEXC_EN) && last_VFP_context[cpu]) {
			vfp_save_state(last_VFP_context[cpu], fpexc);
			last_VFP_context[cpu]->hard.cpu = cpu;
		}
		/*
		 * Thread migration, just force the reloading of the
		 * state on the new CPU in case the VFP registers
		 * contain stale data.
		 */
		if (thread->vfpstate.hard.cpu != cpu)
			last_VFP_context[cpu] = NULL;
#endif

		/*
		 * Always disable VFP so we can lazily save/restore the
		 * old state.
		 */
		fmxr(FPEXC, fpexc & ~FPEXC_EN);
		return NOTIFY_DONE;
	}

	vfp = &thread->vfpstate;
	if (cmd == THREAD_NOTIFY_FLUSH) {
		/*
		 * Per-thread VFP initialisation.
		 */
		memset(vfp, 0, sizeof(union vfp_state));

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

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

	/* flush and release case: Per-thread VFP cleanup. */
	if (last_VFP_context[cpu] == vfp)
		last_VFP_context[cpu] = NULL;

	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 __user *)(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, u32 inst)
{
	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), inst);
	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 == VFP_EXCEPTION_ERROR) {
		vfp_panic("unhandled bounce", inst);
		vfp_raise_sigfpe(0, regs);
		return;
	}

	/*
	 * Update the FPSCR with the additional exception flags.
	 * Comparison instructions always return at least one of
	 * these flags set.
	 */
	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_DZC, FPSCR_DZE, FPE_FLTDIV);
	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 = VFP_EXCEPTION_ERROR;

	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 VFP_bounce(u32 trigger, u32 fpexc, struct pt_regs *regs)
{
	u32 fpscr, orig_fpscr, fpsid, exceptions;

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

	/*
	 * At this point, FPEXC can have the following configuration:
	 *
	 *  EX DEX IXE
	 *  0   1   x   - synchronous exception
	 *  1   x   0   - asynchronous exception
	 *  1   x   1   - sychronous on VFP subarch 1 and asynchronous on later
	 *  0   0   1   - synchronous on VFP9 (non-standard subarch 1
	 *                implementation), undefined otherwise
	 *
	 * Clear various bits and enable access to the VFP so we can
	 * handle the bounce.
	 */
	fmxr(FPEXC, fpexc & ~(FPEXC_EX|FPEXC_DEX|FPEXC_FP2V|FPEXC_VV|FPEXC_TRAP_MASK));

	fpsid = fmrx(FPSID);
	orig_fpscr = fpscr = fmrx(FPSCR);

	/*
	 * Check for the special VFP subarch 1 and FPSCR.IXE bit case
	 */
	if ((fpsid & FPSID_ARCH_MASK) == (1 << FPSID_ARCH_BIT)
	    && (fpscr & FPSCR_IXE)) {
		/*
		 * Synchronous exception, emulate the trigger instruction
		 */
		goto emulate;
	}

	if (fpexc & FPEXC_EX) {
		/*
		 * Asynchronous exception. The instruction is read from FPINST
		 * and the interrupted instruction has to be restarted.
		 */
		trigger = fmrx(FPINST);
		regs->ARM_pc -= 4;
	} else if (!(fpexc & FPEXC_DEX)) {
		/*
		 * Illegal combination of bits. It can be caused by an
		 * unallocated VFP instruction but with FPSCR.IXE set and not
		 * on VFP subarch 1.
		 */
		 vfp_raise_exceptions(VFP_EXCEPTION_ERROR, trigger, fpscr, regs);
		 return;
	}

	/*
	 * Modify fpscr to indicate the number of iterations remaining.
	 * If FPEXC.EX is 0, FPEXC.DEX is 1 and the FPEXC.VV bit indicates
	 * whether FPEXC.VECITR or FPSCR.LEN is used.
	 */
	if (fpexc & (FPEXC_EX | FPEXC_VV)) {
		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.
	 */
	exceptions = vfp_emulate_instruction(trigger, fpscr, regs);
	if (exceptions)
		vfp_raise_exceptions(exceptions, trigger, orig_fpscr, regs);

	/*
	 * If there isn't a second FP instruction, exit now. Note that
	 * the FPEXC.FP2V bit is valid only if FPEXC.EX is 1.
	 */
	if (fpexc ^ (FPEXC_EX | FPEXC_FP2V))
		return;

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

 emulate:
	exceptions = vfp_emulate_instruction(trigger, orig_fpscr, regs);
	if (exceptions)
		vfp_raise_exceptions(exceptions, trigger, orig_fpscr, regs);
}

static void vfp_enable(void *unused)
{
	u32 access = get_copro_access();

	/*
	 * Enable full access to VFP (cp10 and cp11)
	 */
	set_copro_access(access | CPACC_FULL(10) | CPACC_FULL(11));
}

#ifdef CONFIG_PM
#include <linux/sysdev.h>

static int vfp_pm_suspend(struct sys_device *dev, pm_message_t state)
{
	struct thread_info *ti = current_thread_info();
	u32 fpexc = fmrx(FPEXC);

	/* if vfp is on, then save state for resumption */
	if (fpexc & FPEXC_EN) {
		printk(KERN_DEBUG "%s: saving vfp state\n", __func__);
		vfp_save_state(&ti->vfpstate, fpexc);

		/* disable, just in case */
		fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_EN);
	}

	/* clear any information we had about last context state */
	memset(last_VFP_context, 0, sizeof(last_VFP_context));

	return 0;
}

static int vfp_pm_resume(struct sys_device *dev)
{
	/* ensure we have access to the vfp */
	vfp_enable(NULL);

	/* and disable it to ensure the next usage restores the state */
	fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_EN);

	return 0;
}

static struct sysdev_class vfp_pm_sysclass = {
	.name		= "vfp",
	.suspend	= vfp_pm_suspend,
	.resume		= vfp_pm_resume,
};

static struct sys_device vfp_pm_sysdev = {
	.cls	= &vfp_pm_sysclass,
};

static void vfp_pm_init(void)
{
	sysdev_class_register(&vfp_pm_sysclass);
	sysdev_register(&vfp_pm_sysdev);
}


#else
static inline void vfp_pm_init(void) { }
#endif /* CONFIG_PM */

/*
 * Synchronise the hardware VFP state of a thread other than current with the
 * saved one. This function is used by the ptrace mechanism.
 */
#ifdef CONFIG_SMP
void vfp_sync_state(struct thread_info *thread)
{
	/*
	 * On SMP systems, the VFP state is automatically saved at every
	 * context switch. We mark the thread VFP state as belonging to a
	 * non-existent CPU so that the saved one will be reloaded when
	 * needed.
	 */
	thread->vfpstate.hard.cpu = NR_CPUS;
}
#else
void vfp_sync_state(struct thread_info *thread)
{
	unsigned int cpu = get_cpu();
	u32 fpexc = fmrx(FPEXC);

	/*
	 * If VFP is enabled, the previous state was already saved and
	 * last_VFP_context updated.
	 */
	if (fpexc & FPEXC_EN)
		goto out;

	if (!last_VFP_context[cpu])
		goto out;

	/*
	 * Save the last VFP state on this CPU.
	 */
	fmxr(FPEXC, fpexc | FPEXC_EN);
	vfp_save_state(last_VFP_context[cpu], fpexc);
	fmxr(FPEXC, fpexc);

	/*
	 * Set the context to NULL to force a reload the next time the thread
	 * uses the VFP.
	 */
	last_VFP_context[cpu] = NULL;

out:
	put_cpu();
}
#endif

#include <linux/smp.h>

/*
 * VFP support code initialisation.
 */
static int __init vfp_init(void)
{
	unsigned int vfpsid;
	unsigned int cpu_arch = cpu_architecture();

	if (cpu_arch >= CPU_ARCH_ARMv6)
		vfp_enable(NULL);

	/*
	 * 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.
	 */
	vfp_vector = vfp_testing_entry;
	barrier();
	vfpsid = fmrx(FPSID);
	barrier();
	vfp_vector = vfp_null_entry;

	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 {
		smp_call_function(vfp_enable, NULL, 1);

		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);
		vfp_pm_init();

		/*
		 * We detected VFP, and the support code is
		 * in place; report VFP support to userspace.
		 */
		elf_hwcap |= HWCAP_VFP;
#ifdef CONFIG_NEON
		/*
		 * Check for the presence of the Advanced SIMD
		 * load/store instructions, integer and single
		 * precision floating point operations.
		 */
		if ((fmrx(MVFR1) & 0x000fff00) == 0x00011100)
			elf_hwcap |= HWCAP_NEON;
#endif
	}
	return 0;
}

late_initcall(vfp_init);