aboutsummaryrefslogtreecommitdiffstats
path: root/arch/powerpc/kernel/align.c
blob: faaec9c6f78f1aaf5f7f572e5cbd8035c4c063e9 (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
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
/* align.c - handle alignment exceptions for the Power PC.
 *
 * Copyright (c) 1996 Paul Mackerras <paulus@cs.anu.edu.au>
 * Copyright (c) 1998-1999 TiVo, Inc.
 *   PowerPC 403GCX modifications.
 * Copyright (c) 1999 Grant Erickson <grant@lcse.umn.edu>
 *   PowerPC 403GCX/405GP modifications.
 * Copyright (c) 2001-2002 PPC64 team, IBM Corp
 *   64-bit and Power4 support
 * Copyright (c) 2005 Benjamin Herrenschmidt, IBM Corp
 *                    <benh@kernel.crashing.org>
 *   Merge ppc32 and ppc64 implementations
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */

#include <linux/kernel.h>
#include <linux/mm.h>
#include <asm/processor.h>
#include <asm/uaccess.h>
#include <asm/system.h>
#include <asm/cache.h>
#include <asm/cputable.h>

struct aligninfo {
	unsigned char len;
	unsigned char flags;
};

#define IS_XFORM(inst)	(((inst) >> 26) == 31)
#define IS_DSFORM(inst)	(((inst) >> 26) >= 56)

#define INVALID	{ 0, 0 }

#define LD	1	/* load */
#define ST	2	/* store */
#define	SE	4	/* sign-extend value */
#define F	8	/* to/from fp regs */
#define U	0x10	/* update index register */
#define M	0x20	/* multiple load/store */
#define SW	0x40	/* byte swap int or ... */
#define S	0x40	/* ... single-precision fp */
#define SX	0x40	/* byte count in XER */
#define HARD	0x80	/* string, stwcx. */

#define DCBZ	0x5f	/* 8xx/82xx dcbz faults when cache not enabled */

#define SWAP(a, b)	(t = (a), (a) = (b), (b) = t)

/*
 * The PowerPC stores certain bits of the instruction that caused the
 * alignment exception in the DSISR register.  This array maps those
 * bits to information about the operand length and what the
 * instruction would do.
 */
static struct aligninfo aligninfo[128] = {
	{ 4, LD },		/* 00 0 0000: lwz / lwarx */
	INVALID,		/* 00 0 0001 */
	{ 4, ST },		/* 00 0 0010: stw */
	INVALID,		/* 00 0 0011 */
	{ 2, LD },		/* 00 0 0100: lhz */
	{ 2, LD+SE },		/* 00 0 0101: lha */
	{ 2, ST },		/* 00 0 0110: sth */
	{ 4, LD+M },		/* 00 0 0111: lmw */
	{ 4, LD+F+S },		/* 00 0 1000: lfs */
	{ 8, LD+F },		/* 00 0 1001: lfd */
	{ 4, ST+F+S },		/* 00 0 1010: stfs */
	{ 8, ST+F },		/* 00 0 1011: stfd */
	INVALID,		/* 00 0 1100 */
	{ 8, LD },		/* 00 0 1101: ld/ldu/lwa */
	INVALID,		/* 00 0 1110 */
	{ 8, ST },		/* 00 0 1111: std/stdu */
	{ 4, LD+U },		/* 00 1 0000: lwzu */
	INVALID,		/* 00 1 0001 */
	{ 4, ST+U },		/* 00 1 0010: stwu */
	INVALID,		/* 00 1 0011 */
	{ 2, LD+U },		/* 00 1 0100: lhzu */
	{ 2, LD+SE+U },		/* 00 1 0101: lhau */
	{ 2, ST+U },		/* 00 1 0110: sthu */
	{ 4, ST+M },		/* 00 1 0111: stmw */
	{ 4, LD+F+S+U },	/* 00 1 1000: lfsu */
	{ 8, LD+F+U },		/* 00 1 1001: lfdu */
	{ 4, ST+F+S+U },	/* 00 1 1010: stfsu */
	{ 8, ST+F+U },		/* 00 1 1011: stfdu */
	INVALID,		/* 00 1 1100 */
	INVALID,		/* 00 1 1101 */
	INVALID,		/* 00 1 1110 */
	INVALID,		/* 00 1 1111 */
	{ 8, LD },		/* 01 0 0000: ldx */
	INVALID,		/* 01 0 0001 */
	{ 8, ST },		/* 01 0 0010: stdx */
	INVALID,		/* 01 0 0011 */
	INVALID,		/* 01 0 0100 */
	{ 4, LD+SE },		/* 01 0 0101: lwax */
	INVALID,		/* 01 0 0110 */
	INVALID,		/* 01 0 0111 */
	{ 4, LD+M+HARD+SX },	/* 01 0 1000: lswx */
	{ 4, LD+M+HARD },	/* 01 0 1001: lswi */
	{ 4, ST+M+HARD+SX },	/* 01 0 1010: stswx */
	{ 4, ST+M+HARD },	/* 01 0 1011: stswi */
	INVALID,		/* 01 0 1100 */
	{ 8, LD+U },		/* 01 0 1101: ldu */
	INVALID,		/* 01 0 1110 */
	{ 8, ST+U },		/* 01 0 1111: stdu */
	{ 8, LD+U },		/* 01 1 0000: ldux */
	INVALID,		/* 01 1 0001 */
	{ 8, ST+U },		/* 01 1 0010: stdux */
	INVALID,		/* 01 1 0011 */
	INVALID,		/* 01 1 0100 */
	{ 4, LD+SE+U },		/* 01 1 0101: lwaux */
	INVALID,		/* 01 1 0110 */
	INVALID,		/* 01 1 0111 */
	INVALID,		/* 01 1 1000 */
	INVALID,		/* 01 1 1001 */
	INVALID,		/* 01 1 1010 */
	INVALID,		/* 01 1 1011 */
	INVALID,		/* 01 1 1100 */
	INVALID,		/* 01 1 1101 */
	INVALID,		/* 01 1 1110 */
	INVALID,		/* 01 1 1111 */
	INVALID,		/* 10 0 0000 */
	INVALID,		/* 10 0 0001 */
	INVALID,		/* 10 0 0010: stwcx. */
	INVALID,		/* 10 0 0011 */
	INVALID,		/* 10 0 0100 */
	INVALID,		/* 10 0 0101 */
	INVALID,		/* 10 0 0110 */
	INVALID,		/* 10 0 0111 */
	{ 4, LD+SW },		/* 10 0 1000: lwbrx */
	INVALID,		/* 10 0 1001 */
	{ 4, ST+SW },		/* 10 0 1010: stwbrx */
	INVALID,		/* 10 0 1011 */
	{ 2, LD+SW },		/* 10 0 1100: lhbrx */
	{ 4, LD+SE },		/* 10 0 1101  lwa */
	{ 2, ST+SW },		/* 10 0 1110: sthbrx */
	INVALID,		/* 10 0 1111 */
	INVALID,		/* 10 1 0000 */
	INVALID,		/* 10 1 0001 */
	INVALID,		/* 10 1 0010 */
	INVALID,		/* 10 1 0011 */
	INVALID,		/* 10 1 0100 */
	INVALID,		/* 10 1 0101 */
	INVALID,		/* 10 1 0110 */
	INVALID,		/* 10 1 0111 */
	INVALID,		/* 10 1 1000 */
	INVALID,		/* 10 1 1001 */
	INVALID,		/* 10 1 1010 */
	INVALID,		/* 10 1 1011 */
	INVALID,		/* 10 1 1100 */
	INVALID,		/* 10 1 1101 */
	INVALID,		/* 10 1 1110 */
	{ 0, ST+HARD },		/* 10 1 1111: dcbz */
	{ 4, LD },		/* 11 0 0000: lwzx */
	INVALID,		/* 11 0 0001 */
	{ 4, ST },		/* 11 0 0010: stwx */
	INVALID,		/* 11 0 0011 */
	{ 2, LD },		/* 11 0 0100: lhzx */
	{ 2, LD+SE },		/* 11 0 0101: lhax */
	{ 2, ST },		/* 11 0 0110: sthx */
	INVALID,		/* 11 0 0111 */
	{ 4, LD+F+S },		/* 11 0 1000: lfsx */
	{ 8, LD+F },		/* 11 0 1001: lfdx */
	{ 4, ST+F+S },		/* 11 0 1010: stfsx */
	{ 8, ST+F },		/* 11 0 1011: stfdx */
	INVALID,		/* 11 0 1100 */
	{ 8, LD+M },		/* 11 0 1101: lmd */
	INVALID,		/* 11 0 1110 */
	{ 8, ST+M },		/* 11 0 1111: stmd */
	{ 4, LD+U },		/* 11 1 0000: lwzux */
	INVALID,		/* 11 1 0001 */
	{ 4, ST+U },		/* 11 1 0010: stwux */
	INVALID,		/* 11 1 0011 */
	{ 2, LD+U },		/* 11 1 0100: lhzux */
	{ 2, LD+SE+U },		/* 11 1 0101: lhaux */
	{ 2, ST+U },		/* 11 1 0110: sthux */
	INVALID,		/* 11 1 0111 */
	{ 4, LD+F+S+U },	/* 11 1 1000: lfsux */
	{ 8, LD+F+U },		/* 11 1 1001: lfdux */
	{ 4, ST+F+S+U },	/* 11 1 1010: stfsux */
	{ 8, ST+F+U },		/* 11 1 1011: stfdux */
	INVALID,		/* 11 1 1100 */
	INVALID,		/* 11 1 1101 */
	INVALID,		/* 11 1 1110 */
	INVALID,		/* 11 1 1111 */
};

/*
 * Create a DSISR value from the instruction
 */
static inline unsigned make_dsisr(unsigned instr)
{
	unsigned dsisr;


	/* bits  6:15 --> 22:31 */
	dsisr = (instr & 0x03ff0000) >> 16;

	if (IS_XFORM(instr)) {
		/* bits 29:30 --> 15:16 */
		dsisr |= (instr & 0x00000006) << 14;
		/* bit     25 -->    17 */
		dsisr |= (instr & 0x00000040) << 8;
		/* bits 21:24 --> 18:21 */
		dsisr |= (instr & 0x00000780) << 3;
	} else {
		/* bit      5 -->    17 */
		dsisr |= (instr & 0x04000000) >> 12;
		/* bits  1: 4 --> 18:21 */
		dsisr |= (instr & 0x78000000) >> 17;
		/* bits 30:31 --> 12:13 */
		if (IS_DSFORM(instr))
			dsisr |= (instr & 0x00000003) << 18;
	}

	return dsisr;
}

/*
 * The dcbz (data cache block zero) instruction
 * gives an alignment fault if used on non-cacheable
 * memory.  We handle the fault mainly for the
 * case when we are running with the cache disabled
 * for debugging.
 */
static int emulate_dcbz(struct pt_regs *regs, unsigned char __user *addr)
{
	long __user *p;
	int i, size;

#ifdef __powerpc64__
	size = ppc64_caches.dline_size;
#else
	size = L1_CACHE_BYTES;
#endif
	p = (long __user *) (regs->dar & -size);
	if (user_mode(regs) && !access_ok(VERIFY_WRITE, p, size))
		return -EFAULT;
	for (i = 0; i < size / sizeof(long); ++i)
		if (__put_user(0, p+i))
			return -EFAULT;
	return 1;
}

/*
 * Emulate load & store multiple instructions
 * On 64-bit machines, these instructions only affect/use the
 * bottom 4 bytes of each register, and the loads clear the
 * top 4 bytes of the affected register.
 */
#ifdef CONFIG_PPC64
#define REG_BYTE(rp, i)		*((u8 *)((rp) + ((i) >> 2)) + ((i) & 3) + 4)
#else
#define REG_BYTE(rp, i)		*((u8 *)(rp) + (i))
#endif

static int emulate_multiple(struct pt_regs *regs, unsigned char __user *addr,
			    unsigned int reg, unsigned int nb,
			    unsigned int flags, unsigned int instr)
{
	unsigned long *rptr;
	unsigned int nb0, i;

	/*
	 * We do not try to emulate 8 bytes multiple as they aren't really
	 * available in our operating environments and we don't try to
	 * emulate multiples operations in kernel land as they should never
	 * be used/generated there at least not on unaligned boundaries
	 */
	if (unlikely((nb > 4) || !user_mode(regs)))
		return 0;

	/* lmw, stmw, lswi/x, stswi/x */
	nb0 = 0;
	if (flags & HARD) {
		if (flags & SX) {
			nb = regs->xer & 127;
			if (nb == 0)
				return 1;
		} else {
			if (__get_user(instr,
				       (unsigned int __user *)regs->nip))
				return -EFAULT;
			nb = (instr >> 11) & 0x1f;
			if (nb == 0)
				nb = 32;
		}
		if (nb + reg * 4 > 128) {
			nb0 = nb + reg * 4 - 128;
			nb = 128 - reg * 4;
		}
	} else {
		/* lwm, stmw */
		nb = (32 - reg) * 4;
	}

	if (!access_ok((flags & ST ? VERIFY_WRITE: VERIFY_READ), addr, nb+nb0))
		return -EFAULT;	/* bad address */

	rptr = &regs->gpr[reg];
	if (flags & LD) {
		/*
		 * This zeroes the top 4 bytes of the affected registers
		 * in 64-bit mode, and also zeroes out any remaining
		 * bytes of the last register for lsw*.
		 */
		memset(rptr, 0, ((nb + 3) / 4) * sizeof(unsigned long));
		if (nb0 > 0)
			memset(&regs->gpr[0], 0,
			       ((nb0 + 3) / 4) * sizeof(unsigned long));

		for (i = 0; i < nb; ++i)
			if (__get_user(REG_BYTE(rptr, i), addr + i))
				return -EFAULT;
		if (nb0 > 0) {
			rptr = &regs->gpr[0];
			addr += nb;
			for (i = 0; i < nb0; ++i)
				if (__get_user(REG_BYTE(rptr, i), addr + i))
					return -EFAULT;
		}

	} else {
		for (i = 0; i < nb; ++i)
			if (__put_user(REG_BYTE(rptr, i), addr + i))
				return -EFAULT;
		if (nb0 > 0) {
			rptr = &regs->gpr[0];
			addr += nb;
			for (i = 0; i < nb0; ++i)
				if (__put_user(REG_BYTE(rptr, i), addr + i))
					return -EFAULT;
		}
	}
	return 1;
}


/*
 * Called on alignment exception. Attempts to fixup
 *
 * Return 1 on success
 * Return 0 if unable to handle the interrupt
 * Return -EFAULT if data address is bad
 */

int fix_alignment(struct pt_regs *regs)
{
	unsigned int instr, nb, flags;
	unsigned int reg, areg;
	unsigned int dsisr;
	unsigned char __user *addr;
	unsigned char __user *p;
	int ret, t;
	union {
		u64 ll;
		double dd;
		unsigned char v[8];
		struct {
			unsigned hi32;
			int	 low32;
		} x32;
		struct {
			unsigned char hi48[6];
			short	      low16;
		} x16;
	} data;

	/*
	 * We require a complete register set, if not, then our assembly
	 * is broken
	 */
	CHECK_FULL_REGS(regs);

	dsisr = regs->dsisr;

	/* Some processors don't provide us with a DSISR we can use here,
	 * let's make one up from the instruction
	 */
	if (cpu_has_feature(CPU_FTR_NODSISRALIGN)) {
		unsigned int real_instr;
		if (unlikely(__get_user(real_instr,
					(unsigned int __user *)regs->nip)))
			return -EFAULT;
		dsisr = make_dsisr(real_instr);
	}

	/* extract the operation and registers from the dsisr */
	reg = (dsisr >> 5) & 0x1f;	/* source/dest register */
	areg = dsisr & 0x1f;		/* register to update */
	instr = (dsisr >> 10) & 0x7f;
	instr |= (dsisr >> 13) & 0x60;

	/* Lookup the operation in our table */
	nb = aligninfo[instr].len;
	flags = aligninfo[instr].flags;

	/* DAR has the operand effective address */
	addr = (unsigned char __user *)regs->dar;

	/* A size of 0 indicates an instruction we don't support, with
	 * the exception of DCBZ which is handled as a special case here
	 */
	if (instr == DCBZ)
		return emulate_dcbz(regs, addr);
	if (unlikely(nb == 0))
		return 0;

	/* Load/Store Multiple instructions are handled in their own
	 * function
	 */
	if (flags & M)
		return emulate_multiple(regs, addr, reg, nb, flags, instr);

	/* Verify the address of the operand */
	if (unlikely(user_mode(regs) &&
		     !access_ok((flags & ST ? VERIFY_WRITE : VERIFY_READ),
				addr, nb)))
		return -EFAULT;

	/* Force the fprs into the save area so we can reference them */
	if (flags & F) {
		/* userland only */
		if (unlikely(!user_mode(regs)))
			return 0;
		flush_fp_to_thread(current);
	}

	/* If we are loading, get the data from user space, else
	 * get it from register values
	 */
	if (flags & LD) {
		data.ll = 0;
		ret = 0;
		p = addr;
		switch (nb) {
		case 8:
			ret |= __get_user(data.v[0], p++);
			ret |= __get_user(data.v[1], p++);
			ret |= __get_user(data.v[2], p++);
			ret |= __get_user(data.v[3], p++);
		case 4:
			ret |= __get_user(data.v[4], p++);
			ret |= __get_user(data.v[5], p++);
		case 2:
			ret |= __get_user(data.v[6], p++);
			ret |= __get_user(data.v[7], p++);
			if (unlikely(ret))
				return -EFAULT;
		}
	} else if (flags & F)
		data.dd = current->thread.fpr[reg];
	else
		data.ll = regs->gpr[reg];

	/* Perform other misc operations like sign extension, byteswap,
	 * or floating point single precision conversion
	 */
	switch (flags & ~U) {
	case LD+SE:	/* sign extend */
		if ( nb == 2 )
			data.ll = data.x16.low16;
		else	/* nb must be 4 */
			data.ll = data.x32.low32;
		break;
	case LD+S:	/* byte-swap */
	case ST+S:
		if (nb == 2) {
			SWAP(data.v[6], data.v[7]);
		} else {
			SWAP(data.v[4], data.v[7]);
			SWAP(data.v[5], data.v[6]);
		}
		break;

	/* Single-precision FP load and store require conversions... */
	case LD+F+S:
#ifdef CONFIG_PPC_FPU
		preempt_disable();
		enable_kernel_fp();
		cvt_fd((float *)&data.v[4], &data.dd, &current->thread);
		preempt_enable();
#else
		return 0;
#endif
		break;
	case ST+F+S:
#ifdef CONFIG_PPC_FPU
		preempt_disable();
		enable_kernel_fp();
		cvt_df(&data.dd, (float *)&data.v[4], &current->thread);
		preempt_enable();
#else
		return 0;
#endif
		break;
	}

	/* Store result to memory or update registers */
	if (flags & ST) {
		ret = 0;
		p = addr;
		switch (nb) {
		case 8:
			ret |= __put_user(data.v[0], p++);
			ret |= __put_user(data.v[1], p++);
			ret |= __put_user(data.v[2], p++);
			ret |= __put_user(data.v[3], p++);
		case 4:
			ret |= __put_user(data.v[4], p++);
			ret |= __put_user(data.v[5], p++);
		case 2:
			ret |= __put_user(data.v[6], p++);
			ret |= __put_user(data.v[7], p++);
		}
		if (unlikely(ret))
			return -EFAULT;
	} else if (flags & F)
		current->thread.fpr[reg] = data.dd;
	else
		regs->gpr[reg] = data.ll;

	/* Update RA as needed */
	if (flags & U)
		regs->gpr[areg] = regs->dar;

	return 1;
}