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ARM: alignment: correctly decode instructions in BE8 mode.
[linux-2.6/btrfs-unstable.git] / arch / arm / mm / alignment.c
blob924036473b16f437019002b8afac36a2a41e4010
1 /*
2 * linux/arch/arm/mm/alignment.c
3 *
4 * Copyright (C) 1995 Linus Torvalds
5 * Modifications for ARM processor (c) 1995-2001 Russell King
6 * Thumb alignment fault fixups (c) 2004 MontaVista Software, Inc.
7 * - Adapted from gdb/sim/arm/thumbemu.c -- Thumb instruction emulation.
8 * Copyright (C) 1996, Cygnus Software Technologies Ltd.
9 *
10 * This program is free software; you can redistribute it and/or modify
11 * it under the terms of the GNU General Public License version 2 as
12 * published by the Free Software Foundation.
13 */
14 #include <linux/moduleparam.h>
15 #include <linux/compiler.h>
16 #include <linux/kernel.h>
17 #include <linux/errno.h>
18 #include <linux/string.h>
19 #include <linux/proc_fs.h>
20 #include <linux/seq_file.h>
21 #include <linux/init.h>
22 #include <linux/sched.h>
23 #include <linux/uaccess.h>
24
25 #include <asm/cp15.h>
26 #include <asm/system_info.h>
27 #include <asm/unaligned.h>
28 #include <asm/opcodes.h>
29
30 #include "fault.h"
31
32 /*
33 * 32-bit misaligned trap handler (c) 1998 San Mehat (CCC) -July 1998
34 * /proc/sys/debug/alignment, modified and integrated into
35 * Linux 2.1 by Russell King
36 *
37 * Speed optimisations and better fault handling by Russell King.
38 *
39 * *** NOTE ***
40 * This code is not portable to processors with late data abort handling.
41 */
42 #define CODING_BITS(i) (i & 0x0e000000)
43
44 #define LDST_I_BIT(i) (i & (1 << 26)) /* Immediate constant */
45 #define LDST_P_BIT(i) (i & (1 << 24)) /* Preindex */
46 #define LDST_U_BIT(i) (i & (1 << 23)) /* Add offset */
47 #define LDST_W_BIT(i) (i & (1 << 21)) /* Writeback */
48 #define LDST_L_BIT(i) (i & (1 << 20)) /* Load */
49
50 #define LDST_P_EQ_U(i) ((((i) ^ ((i) >> 1)) & (1 << 23)) == 0)
51
52 #define LDSTHD_I_BIT(i) (i & (1 << 22)) /* double/half-word immed */
53 #define LDM_S_BIT(i) (i & (1 << 22)) /* write CPSR from SPSR */
54
55 #define RN_BITS(i) ((i >> 16) & 15) /* Rn */
56 #define RD_BITS(i) ((i >> 12) & 15) /* Rd */
57 #define RM_BITS(i) (i & 15) /* Rm */
58
59 #define REGMASK_BITS(i) (i & 0xffff)
60 #define OFFSET_BITS(i) (i & 0x0fff)
61
62 #define IS_SHIFT(i) (i & 0x0ff0)
63 #define SHIFT_BITS(i) ((i >> 7) & 0x1f)
64 #define SHIFT_TYPE(i) (i & 0x60)
65 #define SHIFT_LSL 0x00
66 #define SHIFT_LSR 0x20
67 #define SHIFT_ASR 0x40
68 #define SHIFT_RORRRX 0x60
69
70 #define BAD_INSTR 0xdeadc0de
71
72 /* Thumb-2 32 bit format per ARMv7 DDI0406A A6.3, either f800h,e800h,f800h */
73 #define IS_T32(hi16) \
74 (((hi16) & 0xe000) == 0xe000 && ((hi16) & 0x1800))
75
76 static unsigned long ai_user;
77 static unsigned long ai_sys;
78 static unsigned long ai_skipped;
79 static unsigned long ai_half;
80 static unsigned long ai_word;
81 static unsigned long ai_dword;
82 static unsigned long ai_multi;
83 static int ai_usermode;
84
85 core_param(alignment, ai_usermode, int, 0600);
86
87 #define UM_WARN (1 << 0)
88 #define UM_FIXUP (1 << 1)
89 #define UM_SIGNAL (1 << 2)
90
91 /* Return true if and only if the ARMv6 unaligned access model is in use. */
92 static bool cpu_is_v6_unaligned(void)
93 {
94 return cpu_architecture() >= CPU_ARCH_ARMv6 && (cr_alignment & CR_U);
95 }
96
97 static int safe_usermode(int new_usermode, bool warn)
98 {
99 /*
100 * ARMv6 and later CPUs can perform unaligned accesses for
101 * most single load and store instructions up to word size.
102 * LDM, STM, LDRD and STRD still need to be handled.
103 *
104 * Ignoring the alignment fault is not an option on these
105 * CPUs since we spin re-faulting the instruction without
106 * making any progress.
107 */
108 if (cpu_is_v6_unaligned() && !(new_usermode & (UM_FIXUP | UM_SIGNAL))) {
109 new_usermode |= UM_FIXUP;
110
111 if (warn)
112 printk(KERN_WARNING "alignment: ignoring faults is unsafe on this CPU. Defaulting to fixup mode.\n");
113 }
114
115 return new_usermode;
116 }
117
118 #ifdef CONFIG_PROC_FS
119 static const char *usermode_action[] = {
120 "ignored",
121 "warn",
122 "fixup",
123 "fixup+warn",
124 "signal",
125 "signal+warn"
126 };
127
128 static int alignment_proc_show(struct seq_file *m, void *v)
129 {
130 seq_printf(m, "User:\t\t%lu\n", ai_user);
131 seq_printf(m, "System:\t\t%lu\n", ai_sys);
132 seq_printf(m, "Skipped:\t%lu\n", ai_skipped);
133 seq_printf(m, "Half:\t\t%lu\n", ai_half);
134 seq_printf(m, "Word:\t\t%lu\n", ai_word);
135 if (cpu_architecture() >= CPU_ARCH_ARMv5TE)
136 seq_printf(m, "DWord:\t\t%lu\n", ai_dword);
137 seq_printf(m, "Multi:\t\t%lu\n", ai_multi);
138 seq_printf(m, "User faults:\t%i (%s)\n", ai_usermode,
139 usermode_action[ai_usermode]);
140
141 return 0;
142 }
143
144 static int alignment_proc_open(struct inode *inode, struct file *file)
145 {
146 return single_open(file, alignment_proc_show, NULL);
147 }
148
149 static ssize_t alignment_proc_write(struct file *file, const char __user *buffer,
150 size_t count, loff_t *pos)
151 {
152 char mode;
153
154 if (count > 0) {
155 if (get_user(mode, buffer))
156 return -EFAULT;
157 if (mode >= '0' && mode <= '5')
158 ai_usermode = safe_usermode(mode - '0', true);
159 }
160 return count;
161 }
162
163 static const struct file_operations alignment_proc_fops = {
164 .open = alignment_proc_open,
165 .read = seq_read,
166 .llseek = seq_lseek,
167 .release = single_release,
168 .write = alignment_proc_write,
169 };
170 #endif /* CONFIG_PROC_FS */
171
172 union offset_union {
173 unsigned long un;
174 signed long sn;
175 };
176
177 #define TYPE_ERROR 0
178 #define TYPE_FAULT 1
179 #define TYPE_LDST 2
180 #define TYPE_DONE 3
181
182 #ifdef __ARMEB__
183 #define BE 1
184 #define FIRST_BYTE_16 "mov %1, %1, ror #8\n"
185 #define FIRST_BYTE_32 "mov %1, %1, ror #24\n"
186 #define NEXT_BYTE "ror #24"
187 #else
188 #define BE 0
189 #define FIRST_BYTE_16
190 #define FIRST_BYTE_32
191 #define NEXT_BYTE "lsr #8"
192 #endif
193
194 #define __get8_unaligned_check(ins,val,addr,err) \
195 __asm__( \
196 ARM( "1: "ins" %1, [%2], #1\n" ) \
197 THUMB( "1: "ins" %1, [%2]\n" ) \
198 THUMB( " add %2, %2, #1\n" ) \
199 "2:\n" \
200 " .pushsection .fixup,\"ax\"\n" \
201 " .align 2\n" \
202 "3: mov %0, #1\n" \
203 " b 2b\n" \
204 " .popsection\n" \
205 " .pushsection __ex_table,\"a\"\n" \
206 " .align 3\n" \
207 " .long 1b, 3b\n" \
208 " .popsection\n" \
209 : "=r" (err), "=&r" (val), "=r" (addr) \
210 : "0" (err), "2" (addr))
211
212 #define __get16_unaligned_check(ins,val,addr) \
213 do { \
214 unsigned int err = 0, v, a = addr; \
215 __get8_unaligned_check(ins,v,a,err); \
216 val = v << ((BE) ? 8 : 0); \
217 __get8_unaligned_check(ins,v,a,err); \
218 val |= v << ((BE) ? 0 : 8); \
219 if (err) \
220 goto fault; \
221 } while (0)
222
223 #define get16_unaligned_check(val,addr) \
224 __get16_unaligned_check("ldrb",val,addr)
225
226 #define get16t_unaligned_check(val,addr) \
227 __get16_unaligned_check("ldrbt",val,addr)
228
229 #define __get32_unaligned_check(ins,val,addr) \
230 do { \
231 unsigned int err = 0, v, a = addr; \
232 __get8_unaligned_check(ins,v,a,err); \
233 val = v << ((BE) ? 24 : 0); \
234 __get8_unaligned_check(ins,v,a,err); \
235 val |= v << ((BE) ? 16 : 8); \
236 __get8_unaligned_check(ins,v,a,err); \
237 val |= v << ((BE) ? 8 : 16); \
238 __get8_unaligned_check(ins,v,a,err); \
239 val |= v << ((BE) ? 0 : 24); \
240 if (err) \
241 goto fault; \
242 } while (0)
243
244 #define get32_unaligned_check(val,addr) \
245 __get32_unaligned_check("ldrb",val,addr)
246
247 #define get32t_unaligned_check(val,addr) \
248 __get32_unaligned_check("ldrbt",val,addr)
249
250 #define __put16_unaligned_check(ins,val,addr) \
251 do { \
252 unsigned int err = 0, v = val, a = addr; \
253 __asm__( FIRST_BYTE_16 \
254 ARM( "1: "ins" %1, [%2], #1\n" ) \
255 THUMB( "1: "ins" %1, [%2]\n" ) \
256 THUMB( " add %2, %2, #1\n" ) \
257 " mov %1, %1, "NEXT_BYTE"\n" \
258 "2: "ins" %1, [%2]\n" \
259 "3:\n" \
260 " .pushsection .fixup,\"ax\"\n" \
261 " .align 2\n" \
262 "4: mov %0, #1\n" \
263 " b 3b\n" \
264 " .popsection\n" \
265 " .pushsection __ex_table,\"a\"\n" \
266 " .align 3\n" \
267 " .long 1b, 4b\n" \
268 " .long 2b, 4b\n" \
269 " .popsection\n" \
270 : "=r" (err), "=&r" (v), "=&r" (a) \
271 : "0" (err), "1" (v), "2" (a)); \
272 if (err) \
273 goto fault; \
274 } while (0)
275
276 #define put16_unaligned_check(val,addr) \
277 __put16_unaligned_check("strb",val,addr)
278
279 #define put16t_unaligned_check(val,addr) \
280 __put16_unaligned_check("strbt",val,addr)
281
282 #define __put32_unaligned_check(ins,val,addr) \
283 do { \
284 unsigned int err = 0, v = val, a = addr; \
285 __asm__( FIRST_BYTE_32 \
286 ARM( "1: "ins" %1, [%2], #1\n" ) \
287 THUMB( "1: "ins" %1, [%2]\n" ) \
288 THUMB( " add %2, %2, #1\n" ) \
289 " mov %1, %1, "NEXT_BYTE"\n" \
290 ARM( "2: "ins" %1, [%2], #1\n" ) \
291 THUMB( "2: "ins" %1, [%2]\n" ) \
292 THUMB( " add %2, %2, #1\n" ) \
293 " mov %1, %1, "NEXT_BYTE"\n" \
294 ARM( "3: "ins" %1, [%2], #1\n" ) \
295 THUMB( "3: "ins" %1, [%2]\n" ) \
296 THUMB( " add %2, %2, #1\n" ) \
297 " mov %1, %1, "NEXT_BYTE"\n" \
298 "4: "ins" %1, [%2]\n" \
299 "5:\n" \
300 " .pushsection .fixup,\"ax\"\n" \
301 " .align 2\n" \
302 "6: mov %0, #1\n" \
303 " b 5b\n" \
304 " .popsection\n" \
305 " .pushsection __ex_table,\"a\"\n" \
306 " .align 3\n" \
307 " .long 1b, 6b\n" \
308 " .long 2b, 6b\n" \
309 " .long 3b, 6b\n" \
310 " .long 4b, 6b\n" \
311 " .popsection\n" \
312 : "=r" (err), "=&r" (v), "=&r" (a) \
313 : "0" (err), "1" (v), "2" (a)); \
314 if (err) \
315 goto fault; \
316 } while (0)
317
318 #define put32_unaligned_check(val,addr) \
319 __put32_unaligned_check("strb", val, addr)
320
321 #define put32t_unaligned_check(val,addr) \
322 __put32_unaligned_check("strbt", val, addr)
323
324 static void
325 do_alignment_finish_ldst(unsigned long addr, unsigned long instr, struct pt_regs *regs, union offset_union offset)
326 {
327 if (!LDST_U_BIT(instr))
328 offset.un = -offset.un;
329
330 if (!LDST_P_BIT(instr))
331 addr += offset.un;
332
333 if (!LDST_P_BIT(instr) || LDST_W_BIT(instr))
334 regs->uregs[RN_BITS(instr)] = addr;
335 }
336
337 static int
338 do_alignment_ldrhstrh(unsigned long addr, unsigned long instr, struct pt_regs *regs)
339 {
340 unsigned int rd = RD_BITS(instr);
341
342 ai_half += 1;
343
344 if (user_mode(regs))
345 goto user;
346
347 if (LDST_L_BIT(instr)) {
348 unsigned long val;
349 get16_unaligned_check(val, addr);
350
351 /* signed half-word? */
352 if (instr & 0x40)
353 val = (signed long)((signed short) val);
354
355 regs->uregs[rd] = val;
356 } else
357 put16_unaligned_check(regs->uregs[rd], addr);
358
359 return TYPE_LDST;
360
361 user:
362 if (LDST_L_BIT(instr)) {
363 unsigned long val;
364 get16t_unaligned_check(val, addr);
365
366 /* signed half-word? */
367 if (instr & 0x40)
368 val = (signed long)((signed short) val);
369
370 regs->uregs[rd] = val;
371 } else
372 put16t_unaligned_check(regs->uregs[rd], addr);
373
374 return TYPE_LDST;
375
376 fault:
377 return TYPE_FAULT;
378 }
379
380 static int
381 do_alignment_ldrdstrd(unsigned long addr, unsigned long instr,
382 struct pt_regs *regs)
383 {
384 unsigned int rd = RD_BITS(instr);
385 unsigned int rd2;
386 int load;
387
388 if ((instr & 0xfe000000) == 0xe8000000) {
389 /* ARMv7 Thumb-2 32-bit LDRD/STRD */
390 rd2 = (instr >> 8) & 0xf;
391 load = !!(LDST_L_BIT(instr));
392 } else if (((rd & 1) == 1) || (rd == 14))
393 goto bad;
394 else {
395 load = ((instr & 0xf0) == 0xd0);
396 rd2 = rd + 1;
397 }
398
399 ai_dword += 1;
400
401 if (user_mode(regs))
402 goto user;
403
404 if (load) {
405 unsigned long val;
406 get32_unaligned_check(val, addr);
407 regs->uregs[rd] = val;
408 get32_unaligned_check(val, addr + 4);
409 regs->uregs[rd2] = val;
410 } else {
411 put32_unaligned_check(regs->uregs[rd], addr);
412 put32_unaligned_check(regs->uregs[rd2], addr + 4);
413 }
414
415 return TYPE_LDST;
416
417 user:
418 if (load) {
419 unsigned long val;
420 get32t_unaligned_check(val, addr);
421 regs->uregs[rd] = val;
422 get32t_unaligned_check(val, addr + 4);
423 regs->uregs[rd2] = val;
424 } else {
425 put32t_unaligned_check(regs->uregs[rd], addr);
426 put32t_unaligned_check(regs->uregs[rd2], addr + 4);
427 }
428
429 return TYPE_LDST;
430 bad:
431 return TYPE_ERROR;
432 fault:
433 return TYPE_FAULT;
434 }
435
436 static int
437 do_alignment_ldrstr(unsigned long addr, unsigned long instr, struct pt_regs *regs)
438 {
439 unsigned int rd = RD_BITS(instr);
440
441 ai_word += 1;
442
443 if ((!LDST_P_BIT(instr) && LDST_W_BIT(instr)) || user_mode(regs))
444 goto trans;
445
446 if (LDST_L_BIT(instr)) {
447 unsigned int val;
448 get32_unaligned_check(val, addr);
449 regs->uregs[rd] = val;
450 } else
451 put32_unaligned_check(regs->uregs[rd], addr);
452 return TYPE_LDST;
453
454 trans:
455 if (LDST_L_BIT(instr)) {
456 unsigned int val;
457 get32t_unaligned_check(val, addr);
458 regs->uregs[rd] = val;
459 } else
460 put32t_unaligned_check(regs->uregs[rd], addr);
461 return TYPE_LDST;
462
463 fault:
464 return TYPE_FAULT;
465 }
466
467 /*
468 * LDM/STM alignment handler.
469 *
470 * There are 4 variants of this instruction:
471 *
472 * B = rn pointer before instruction, A = rn pointer after instruction
473 * ------ increasing address ----->
474 * | | r0 | r1 | ... | rx | |
475 * PU = 01 B A
476 * PU = 11 B A
477 * PU = 00 A B
478 * PU = 10 A B
479 */
480 static int
481 do_alignment_ldmstm(unsigned long addr, unsigned long instr, struct pt_regs *regs)
482 {
483 unsigned int rd, rn, correction, nr_regs, regbits;
484 unsigned long eaddr, newaddr;
485
486 if (LDM_S_BIT(instr))
487 goto bad;
488
489 correction = 4; /* processor implementation defined */
490 regs->ARM_pc += correction;
491
492 ai_multi += 1;
493
494 /* count the number of registers in the mask to be transferred */
495 nr_regs = hweight16(REGMASK_BITS(instr)) * 4;
496
497 rn = RN_BITS(instr);
498 newaddr = eaddr = regs->uregs[rn];
499
500 if (!LDST_U_BIT(instr))
501 nr_regs = -nr_regs;
502 newaddr += nr_regs;
503 if (!LDST_U_BIT(instr))
504 eaddr = newaddr;
505
506 if (LDST_P_EQ_U(instr)) /* U = P */
507 eaddr += 4;
508
509 /*
510 * For alignment faults on the ARM922T/ARM920T the MMU makes
511 * the FSR (and hence addr) equal to the updated base address
512 * of the multiple access rather than the restored value.
513 * Switch this message off if we've got a ARM92[02], otherwise
514 * [ls]dm alignment faults are noisy!
515 */
516 #if !(defined CONFIG_CPU_ARM922T) && !(defined CONFIG_CPU_ARM920T)
517 /*
518 * This is a "hint" - we already have eaddr worked out by the
519 * processor for us.
520 */
521 if (addr != eaddr) {
522 printk(KERN_ERR "LDMSTM: PC = %08lx, instr = %08lx, "
523 "addr = %08lx, eaddr = %08lx\n",
524 instruction_pointer(regs), instr, addr, eaddr);
525 show_regs(regs);
526 }
527 #endif
528
529 if (user_mode(regs)) {
530 for (regbits = REGMASK_BITS(instr), rd = 0; regbits;
531 regbits >>= 1, rd += 1)
532 if (regbits & 1) {
533 if (LDST_L_BIT(instr)) {
534 unsigned int val;
535 get32t_unaligned_check(val, eaddr);
536 regs->uregs[rd] = val;
537 } else
538 put32t_unaligned_check(regs->uregs[rd], eaddr);
539 eaddr += 4;
540 }
541 } else {
542 for (regbits = REGMASK_BITS(instr), rd = 0; regbits;
543 regbits >>= 1, rd += 1)
544 if (regbits & 1) {
545 if (LDST_L_BIT(instr)) {
546 unsigned int val;
547 get32_unaligned_check(val, eaddr);
548 regs->uregs[rd] = val;
549 } else
550 put32_unaligned_check(regs->uregs[rd], eaddr);
551 eaddr += 4;
552 }
553 }
554
555 if (LDST_W_BIT(instr))
556 regs->uregs[rn] = newaddr;
557 if (!LDST_L_BIT(instr) || !(REGMASK_BITS(instr) & (1 << 15)))
558 regs->ARM_pc -= correction;
559 return TYPE_DONE;
560
561 fault:
562 regs->ARM_pc -= correction;
563 return TYPE_FAULT;
564
565 bad:
566 printk(KERN_ERR "Alignment trap: not handling ldm with s-bit set\n");
567 return TYPE_ERROR;
568 }
569
570 /*
571 * Convert Thumb ld/st instruction forms to equivalent ARM instructions so
572 * we can reuse ARM userland alignment fault fixups for Thumb.
573 *
574 * This implementation was initially based on the algorithm found in
575 * gdb/sim/arm/thumbemu.c. It is basically just a code reduction of same
576 * to convert only Thumb ld/st instruction forms to equivalent ARM forms.
577 *
578 * NOTES:
579 * 1. Comments below refer to ARM ARM DDI0100E Thumb Instruction sections.
580 * 2. If for some reason we're passed an non-ld/st Thumb instruction to
581 * decode, we return 0xdeadc0de. This should never happen under normal
582 * circumstances but if it does, we've got other problems to deal with
583 * elsewhere and we obviously can't fix those problems here.
584 */
585
586 static unsigned long
587 thumb2arm(u16 tinstr)
588 {
589 u32 L = (tinstr & (1<<11)) >> 11;
590
591 switch ((tinstr & 0xf800) >> 11) {
592 /* 6.5.1 Format 1: */
593 case 0x6000 >> 11: /* 7.1.52 STR(1) */
594 case 0x6800 >> 11: /* 7.1.26 LDR(1) */
595 case 0x7000 >> 11: /* 7.1.55 STRB(1) */
596 case 0x7800 >> 11: /* 7.1.30 LDRB(1) */
597 return 0xe5800000 |
598 ((tinstr & (1<<12)) << (22-12)) | /* fixup */
599 (L<<20) | /* L==1? */
600 ((tinstr & (7<<0)) << (12-0)) | /* Rd */
601 ((tinstr & (7<<3)) << (16-3)) | /* Rn */
602 ((tinstr & (31<<6)) >> /* immed_5 */
603 (6 - ((tinstr & (1<<12)) ? 0 : 2)));
604 case 0x8000 >> 11: /* 7.1.57 STRH(1) */
605 case 0x8800 >> 11: /* 7.1.32 LDRH(1) */
606 return 0xe1c000b0 |
607 (L<<20) | /* L==1? */
608 ((tinstr & (7<<0)) << (12-0)) | /* Rd */
609 ((tinstr & (7<<3)) << (16-3)) | /* Rn */
610 ((tinstr & (7<<6)) >> (6-1)) | /* immed_5[2:0] */
611 ((tinstr & (3<<9)) >> (9-8)); /* immed_5[4:3] */
612
613 /* 6.5.1 Format 2: */
614 case 0x5000 >> 11:
615 case 0x5800 >> 11:
616 {
617 static const u32 subset[8] = {
618 0xe7800000, /* 7.1.53 STR(2) */
619 0xe18000b0, /* 7.1.58 STRH(2) */
620 0xe7c00000, /* 7.1.56 STRB(2) */
621 0xe19000d0, /* 7.1.34 LDRSB */
622 0xe7900000, /* 7.1.27 LDR(2) */
623 0xe19000b0, /* 7.1.33 LDRH(2) */
624 0xe7d00000, /* 7.1.31 LDRB(2) */
625 0xe19000f0 /* 7.1.35 LDRSH */
626 };
627 return subset[(tinstr & (7<<9)) >> 9] |
628 ((tinstr & (7<<0)) << (12-0)) | /* Rd */
629 ((tinstr & (7<<3)) << (16-3)) | /* Rn */
630 ((tinstr & (7<<6)) >> (6-0)); /* Rm */
631 }
632
633 /* 6.5.1 Format 3: */
634 case 0x4800 >> 11: /* 7.1.28 LDR(3) */
635 /* NOTE: This case is not technically possible. We're
636 * loading 32-bit memory data via PC relative
637 * addressing mode. So we can and should eliminate
638 * this case. But I'll leave it here for now.
639 */
640 return 0xe59f0000 |
641 ((tinstr & (7<<8)) << (12-8)) | /* Rd */
642 ((tinstr & 255) << (2-0)); /* immed_8 */
643
644 /* 6.5.1 Format 4: */
645 case 0x9000 >> 11: /* 7.1.54 STR(3) */
646 case 0x9800 >> 11: /* 7.1.29 LDR(4) */
647 return 0xe58d0000 |
648 (L<<20) | /* L==1? */
649 ((tinstr & (7<<8)) << (12-8)) | /* Rd */
650 ((tinstr & 255) << 2); /* immed_8 */
651
652 /* 6.6.1 Format 1: */
653 case 0xc000 >> 11: /* 7.1.51 STMIA */
654 case 0xc800 >> 11: /* 7.1.25 LDMIA */
655 {
656 u32 Rn = (tinstr & (7<<8)) >> 8;
657 u32 W = ((L<<Rn) & (tinstr&255)) ? 0 : 1<<21;
658
659 return 0xe8800000 | W | (L<<20) | (Rn<<16) |
660 (tinstr&255);
661 }
662
663 /* 6.6.1 Format 2: */
664 case 0xb000 >> 11: /* 7.1.48 PUSH */
665 case 0xb800 >> 11: /* 7.1.47 POP */
666 if ((tinstr & (3 << 9)) == 0x0400) {
667 static const u32 subset[4] = {
668 0xe92d0000, /* STMDB sp!,{registers} */
669 0xe92d4000, /* STMDB sp!,{registers,lr} */
670 0xe8bd0000, /* LDMIA sp!,{registers} */
671 0xe8bd8000 /* LDMIA sp!,{registers,pc} */
672 };
673 return subset[(L<<1) | ((tinstr & (1<<8)) >> 8)] |
674 (tinstr & 255); /* register_list */
675 }
676 /* Else fall through for illegal instruction case */
677
678 default:
679 return BAD_INSTR;
680 }
681 }
682
683 /*
684 * Convert Thumb-2 32 bit LDM, STM, LDRD, STRD to equivalent instruction
685 * handlable by ARM alignment handler, also find the corresponding handler,
686 * so that we can reuse ARM userland alignment fault fixups for Thumb.
687 *
688 * @pinstr: original Thumb-2 instruction; returns new handlable instruction
689 * @regs: register context.
690 * @poffset: return offset from faulted addr for later writeback
691 *
692 * NOTES:
693 * 1. Comments below refer to ARMv7 DDI0406A Thumb Instruction sections.
694 * 2. Register name Rt from ARMv7 is same as Rd from ARMv6 (Rd is Rt)
695 */
696 static void *
697 do_alignment_t32_to_handler(unsigned long *pinstr, struct pt_regs *regs,
698 union offset_union *poffset)
699 {
700 unsigned long instr = *pinstr;
701 u16 tinst1 = (instr >> 16) & 0xffff;
702 u16 tinst2 = instr & 0xffff;
703
704 switch (tinst1 & 0xffe0) {
705 /* A6.3.5 Load/Store multiple */
706 case 0xe880: /* STM/STMIA/STMEA,LDM/LDMIA, PUSH/POP T2 */
707 case 0xe8a0: /* ...above writeback version */
708 case 0xe900: /* STMDB/STMFD, LDMDB/LDMEA */
709 case 0xe920: /* ...above writeback version */
710 /* no need offset decision since handler calculates it */
711 return do_alignment_ldmstm;
712
713 case 0xf840: /* POP/PUSH T3 (single register) */
714 if (RN_BITS(instr) == 13 && (tinst2 & 0x09ff) == 0x0904) {
715 u32 L = !!(LDST_L_BIT(instr));
716 const u32 subset[2] = {
717 0xe92d0000, /* STMDB sp!,{registers} */
718 0xe8bd0000, /* LDMIA sp!,{registers} */
719 };
720 *pinstr = subset[L] | (1<<RD_BITS(instr));
721 return do_alignment_ldmstm;
722 }
723 /* Else fall through for illegal instruction case */
724 break;
725
726 /* A6.3.6 Load/store double, STRD/LDRD(immed, lit, reg) */
727 case 0xe860:
728 case 0xe960:
729 case 0xe8e0:
730 case 0xe9e0:
731 poffset->un = (tinst2 & 0xff) << 2;
732 case 0xe940:
733 case 0xe9c0:
734 return do_alignment_ldrdstrd;
735
736 /*
737 * No need to handle load/store instructions up to word size
738 * since ARMv6 and later CPUs can perform unaligned accesses.
739 */
740 default:
741 break;
742 }
743 return NULL;
744 }
745
746 static int
747 do_alignment(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
748 {
749 union offset_union uninitialized_var(offset);
750 unsigned long instr = 0, instrptr;
751 int (*handler)(unsigned long addr, unsigned long instr, struct pt_regs *regs);
752 unsigned int type;
753 unsigned int fault;
754 u16 tinstr = 0;
755 int isize = 4;
756 int thumb2_32b = 0;
757
758 if (interrupts_enabled(regs))
759 local_irq_enable();
760
761 instrptr = instruction_pointer(regs);
762
763 if (thumb_mode(regs)) {
764 u16 *ptr = (u16 *)(instrptr & ~1);
765 fault = probe_kernel_address(ptr, tinstr);
766 tinstr = __mem_to_opcode_thumb16(tinstr);
767 if (!fault) {
768 if (cpu_architecture() >= CPU_ARCH_ARMv7 &&
769 IS_T32(tinstr)) {
770 /* Thumb-2 32-bit */
771 u16 tinst2 = 0;
772 fault = probe_kernel_address(ptr + 1, tinst2);
773 tinst2 = __mem_to_opcode_thumb16(tinst2);
774 instr = __opcode_thumb32_compose(tinstr, tinst2);
775 thumb2_32b = 1;
776 } else {
777 isize = 2;
778 instr = thumb2arm(tinstr);
779 }
780 }
781 } else {
782 fault = probe_kernel_address(instrptr, instr);
783 instr = __mem_to_opcode_arm(instr);
784 }
785
786 if (fault) {
787 type = TYPE_FAULT;
788 goto bad_or_fault;
789 }
790
791 if (user_mode(regs))
792 goto user;
793
794 ai_sys += 1;
795
796 fixup:
797
798 regs->ARM_pc += isize;
799
800 switch (CODING_BITS(instr)) {
801 case 0x00000000: /* 3.13.4 load/store instruction extensions */
802 if (LDSTHD_I_BIT(instr))
803 offset.un = (instr & 0xf00) >> 4 | (instr & 15);
804 else
805 offset.un = regs->uregs[RM_BITS(instr)];
806
807 if ((instr & 0x000000f0) == 0x000000b0 || /* LDRH, STRH */
808 (instr & 0x001000f0) == 0x001000f0) /* LDRSH */
809 handler = do_alignment_ldrhstrh;
810 else if ((instr & 0x001000f0) == 0x000000d0 || /* LDRD */
811 (instr & 0x001000f0) == 0x000000f0) /* STRD */
812 handler = do_alignment_ldrdstrd;
813 else if ((instr & 0x01f00ff0) == 0x01000090) /* SWP */
814 goto swp;
815 else
816 goto bad;
817 break;
818
819 case 0x04000000: /* ldr or str immediate */
820 offset.un = OFFSET_BITS(instr);
821 handler = do_alignment_ldrstr;
822 break;
823
824 case 0x06000000: /* ldr or str register */
825 offset.un = regs->uregs[RM_BITS(instr)];
826
827 if (IS_SHIFT(instr)) {
828 unsigned int shiftval = SHIFT_BITS(instr);
829
830 switch(SHIFT_TYPE(instr)) {
831 case SHIFT_LSL:
832 offset.un <<= shiftval;
833 break;
834
835 case SHIFT_LSR:
836 offset.un >>= shiftval;
837 break;
838
839 case SHIFT_ASR:
840 offset.sn >>= shiftval;
841 break;
842
843 case SHIFT_RORRRX:
844 if (shiftval == 0) {
845 offset.un >>= 1;
846 if (regs->ARM_cpsr & PSR_C_BIT)
847 offset.un |= 1 << 31;
848 } else
849 offset.un = offset.un >> shiftval |
850 offset.un << (32 - shiftval);
851 break;
852 }
853 }
854 handler = do_alignment_ldrstr;
855 break;
856
857 case 0x08000000: /* ldm or stm, or thumb-2 32bit instruction */
858 if (thumb2_32b) {
859 offset.un = 0;
860 handler = do_alignment_t32_to_handler(&instr, regs, &offset);
861 } else {
862 offset.un = 0;
863 handler = do_alignment_ldmstm;
864 }
865 break;
866
867 default:
868 goto bad;
869 }
870
871 if (!handler)
872 goto bad;
873 type = handler(addr, instr, regs);
874
875 if (type == TYPE_ERROR || type == TYPE_FAULT) {
876 regs->ARM_pc -= isize;
877 goto bad_or_fault;
878 }
879
880 if (type == TYPE_LDST)
881 do_alignment_finish_ldst(addr, instr, regs, offset);
882
883 return 0;
884
885 bad_or_fault:
886 if (type == TYPE_ERROR)
887 goto bad;
888 /*
889 * We got a fault - fix it up, or die.
890 */
891 do_bad_area(addr, fsr, regs);
892 return 0;
893
894 swp:
895 printk(KERN_ERR "Alignment trap: not handling swp instruction\n");
896
897 bad:
898 /*
899 * Oops, we didn't handle the instruction.
900 */
901 printk(KERN_ERR "Alignment trap: not handling instruction "
902 "%0*lx at [<%08lx>]\n",
903 isize << 1,
904 isize == 2 ? tinstr : instr, instrptr);
905 ai_skipped += 1;
906 return 1;
907
908 user:
909 ai_user += 1;
910
911 if (ai_usermode & UM_WARN)
912 printk("Alignment trap: %s (%d) PC=0x%08lx Instr=0x%0*lx "
913 "Address=0x%08lx FSR 0x%03x\n", current->comm,
914 task_pid_nr(current), instrptr,
915 isize << 1,
916 isize == 2 ? tinstr : instr,
917 addr, fsr);
918
919 if (ai_usermode & UM_FIXUP)
920 goto fixup;
921
922 if (ai_usermode & UM_SIGNAL) {
923 siginfo_t si;
924
925 si.si_signo = SIGBUS;
926 si.si_errno = 0;
927 si.si_code = BUS_ADRALN;
928 si.si_addr = (void __user *)addr;
929
930 force_sig_info(si.si_signo, &si, current);
931 } else {
932 /*
933 * We're about to disable the alignment trap and return to
934 * user space. But if an interrupt occurs before actually
935 * reaching user space, then the IRQ vector entry code will
936 * notice that we were still in kernel space and therefore
937 * the alignment trap won't be re-enabled in that case as it
938 * is presumed to be always on from kernel space.
939 * Let's prevent that race by disabling interrupts here (they
940 * are disabled on the way back to user space anyway in
941 * entry-common.S) and disable the alignment trap only if
942 * there is no work pending for this thread.
943 */
944 raw_local_irq_disable();
945 if (!(current_thread_info()->flags & _TIF_WORK_MASK))
946 set_cr(cr_no_alignment);
947 }
948
949 return 0;
950 }
951
952 /*
953 * This needs to be done after sysctl_init, otherwise sys/ will be
954 * overwritten. Actually, this shouldn't be in sys/ at all since
955 * it isn't a sysctl, and it doesn't contain sysctl information.
956 * We now locate it in /proc/cpu/alignment instead.
957 */
958 static int __init alignment_init(void)
959 {
960 #ifdef CONFIG_PROC_FS
961 struct proc_dir_entry *res;
962
963 res = proc_create("cpu/alignment", S_IWUSR | S_IRUGO, NULL,
964 &alignment_proc_fops);
965 if (!res)
966 return -ENOMEM;
967 #endif
968
969 #ifdef CONFIG_CPU_CP15
970 if (cpu_is_v6_unaligned()) {
971 cr_alignment &= ~CR_A;
972 cr_no_alignment &= ~CR_A;
973 set_cr(cr_alignment);
974 ai_usermode = safe_usermode(ai_usermode, false);
975 }
976 #endif
977
978 hook_fault_code(FAULT_CODE_ALIGNMENT, do_alignment, SIGBUS, BUS_ADRALN,
979 "alignment exception");
980
981 /*
982 * ARMv6K and ARMv7 use fault status 3 (0b00011) as Access Flag section
983 * fault, not as alignment error.
984 *
985 * TODO: handle ARMv6K properly. Runtime check for 'K' extension is
986 * needed.
987 */
988 if (cpu_architecture() <= CPU_ARCH_ARMv6) {
989 hook_fault_code(3, do_alignment, SIGBUS, BUS_ADRALN,
990 "alignment exception");
991 }
992
993 return 0;
994 }
995
996 fs_initcall(alignment_init);
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