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[mirror_ubuntu-bionic-kernel.git] / arch / arm / mm / alignment.c
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 aligment 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/compiler.h>
15 #include <linux/kernel.h>
16 #include <linux/errno.h>
17 #include <linux/string.h>
18 #include <linux/proc_fs.h>
19 #include <linux/init.h>
20
21 #include <asm/uaccess.h>
22 #include <asm/unaligned.h>
23
24 #include "fault.h"
25
26 /*
27 * 32-bit misaligned trap handler (c) 1998 San Mehat (CCC) -July 1998
28 * /proc/sys/debug/alignment, modified and integrated into
29 * Linux 2.1 by Russell King
30 *
31 * Speed optimisations and better fault handling by Russell King.
32 *
33 * *** NOTE ***
34 * This code is not portable to processors with late data abort handling.
35 */
36 #define CODING_BITS(i) (i & 0x0e000000)
37
38 #define LDST_I_BIT(i) (i & (1 << 26)) /* Immediate constant */
39 #define LDST_P_BIT(i) (i & (1 << 24)) /* Preindex */
40 #define LDST_U_BIT(i) (i & (1 << 23)) /* Add offset */
41 #define LDST_W_BIT(i) (i & (1 << 21)) /* Writeback */
42 #define LDST_L_BIT(i) (i & (1 << 20)) /* Load */
43
44 #define LDST_P_EQ_U(i) ((((i) ^ ((i) >> 1)) & (1 << 23)) == 0)
45
46 #define LDSTHD_I_BIT(i) (i & (1 << 22)) /* double/half-word immed */
47 #define LDM_S_BIT(i) (i & (1 << 22)) /* write CPSR from SPSR */
48
49 #define RN_BITS(i) ((i >> 16) & 15) /* Rn */
50 #define RD_BITS(i) ((i >> 12) & 15) /* Rd */
51 #define RM_BITS(i) (i & 15) /* Rm */
52
53 #define REGMASK_BITS(i) (i & 0xffff)
54 #define OFFSET_BITS(i) (i & 0x0fff)
55
56 #define IS_SHIFT(i) (i & 0x0ff0)
57 #define SHIFT_BITS(i) ((i >> 7) & 0x1f)
58 #define SHIFT_TYPE(i) (i & 0x60)
59 #define SHIFT_LSL 0x00
60 #define SHIFT_LSR 0x20
61 #define SHIFT_ASR 0x40
62 #define SHIFT_RORRRX 0x60
63
64 static unsigned long ai_user;
65 static unsigned long ai_sys;
66 static unsigned long ai_skipped;
67 static unsigned long ai_half;
68 static unsigned long ai_word;
69 static unsigned long ai_dword;
70 static unsigned long ai_multi;
71 static int ai_usermode;
72
73 #ifdef CONFIG_PROC_FS
74 static const char *usermode_action[] = {
75 "ignored",
76 "warn",
77 "fixup",
78 "fixup+warn",
79 "signal",
80 "signal+warn"
81 };
82
83 static int
84 proc_alignment_read(char *page, char **start, off_t off, int count, int *eof,
85 void *data)
86 {
87 char *p = page;
88 int len;
89
90 p += sprintf(p, "User:\t\t%lu\n", ai_user);
91 p += sprintf(p, "System:\t\t%lu\n", ai_sys);
92 p += sprintf(p, "Skipped:\t%lu\n", ai_skipped);
93 p += sprintf(p, "Half:\t\t%lu\n", ai_half);
94 p += sprintf(p, "Word:\t\t%lu\n", ai_word);
95 if (cpu_architecture() >= CPU_ARCH_ARMv5TE)
96 p += sprintf(p, "DWord:\t\t%lu\n", ai_dword);
97 p += sprintf(p, "Multi:\t\t%lu\n", ai_multi);
98 p += sprintf(p, "User faults:\t%i (%s)\n", ai_usermode,
99 usermode_action[ai_usermode]);
100
101 len = (p - page) - off;
102 if (len < 0)
103 len = 0;
104
105 *eof = (len <= count) ? 1 : 0;
106 *start = page + off;
107
108 return len;
109 }
110
111 static int proc_alignment_write(struct file *file, const char __user *buffer,
112 unsigned long count, void *data)
113 {
114 char mode;
115
116 if (count > 0) {
117 if (get_user(mode, buffer))
118 return -EFAULT;
119 if (mode >= '0' && mode <= '5')
120 ai_usermode = mode - '0';
121 }
122 return count;
123 }
124
125 #endif /* CONFIG_PROC_FS */
126
127 union offset_union {
128 unsigned long un;
129 signed long sn;
130 };
131
132 #define TYPE_ERROR 0
133 #define TYPE_FAULT 1
134 #define TYPE_LDST 2
135 #define TYPE_DONE 3
136
137 #ifdef __ARMEB__
138 #define BE 1
139 #define FIRST_BYTE_16 "mov %1, %1, ror #8\n"
140 #define FIRST_BYTE_32 "mov %1, %1, ror #24\n"
141 #define NEXT_BYTE "ror #24"
142 #else
143 #define BE 0
144 #define FIRST_BYTE_16
145 #define FIRST_BYTE_32
146 #define NEXT_BYTE "lsr #8"
147 #endif
148
149 #define __get8_unaligned_check(ins,val,addr,err) \
150 __asm__( \
151 "1: "ins" %1, [%2], #1\n" \
152 "2:\n" \
153 " .section .fixup,\"ax\"\n" \
154 " .align 2\n" \
155 "3: mov %0, #1\n" \
156 " b 2b\n" \
157 " .previous\n" \
158 " .section __ex_table,\"a\"\n" \
159 " .align 3\n" \
160 " .long 1b, 3b\n" \
161 " .previous\n" \
162 : "=r" (err), "=&r" (val), "=r" (addr) \
163 : "0" (err), "2" (addr))
164
165 #define __get16_unaligned_check(ins,val,addr) \
166 do { \
167 unsigned int err = 0, v, a = addr; \
168 __get8_unaligned_check(ins,v,a,err); \
169 val = v << ((BE) ? 8 : 0); \
170 __get8_unaligned_check(ins,v,a,err); \
171 val |= v << ((BE) ? 0 : 8); \
172 if (err) \
173 goto fault; \
174 } while (0)
175
176 #define get16_unaligned_check(val,addr) \
177 __get16_unaligned_check("ldrb",val,addr)
178
179 #define get16t_unaligned_check(val,addr) \
180 __get16_unaligned_check("ldrbt",val,addr)
181
182 #define __get32_unaligned_check(ins,val,addr) \
183 do { \
184 unsigned int err = 0, v, a = addr; \
185 __get8_unaligned_check(ins,v,a,err); \
186 val = v << ((BE) ? 24 : 0); \
187 __get8_unaligned_check(ins,v,a,err); \
188 val |= v << ((BE) ? 16 : 8); \
189 __get8_unaligned_check(ins,v,a,err); \
190 val |= v << ((BE) ? 8 : 16); \
191 __get8_unaligned_check(ins,v,a,err); \
192 val |= v << ((BE) ? 0 : 24); \
193 if (err) \
194 goto fault; \
195 } while (0)
196
197 #define get32_unaligned_check(val,addr) \
198 __get32_unaligned_check("ldrb",val,addr)
199
200 #define get32t_unaligned_check(val,addr) \
201 __get32_unaligned_check("ldrbt",val,addr)
202
203 #define __put16_unaligned_check(ins,val,addr) \
204 do { \
205 unsigned int err = 0, v = val, a = addr; \
206 __asm__( FIRST_BYTE_16 \
207 "1: "ins" %1, [%2], #1\n" \
208 " mov %1, %1, "NEXT_BYTE"\n" \
209 "2: "ins" %1, [%2]\n" \
210 "3:\n" \
211 " .section .fixup,\"ax\"\n" \
212 " .align 2\n" \
213 "4: mov %0, #1\n" \
214 " b 3b\n" \
215 " .previous\n" \
216 " .section __ex_table,\"a\"\n" \
217 " .align 3\n" \
218 " .long 1b, 4b\n" \
219 " .long 2b, 4b\n" \
220 " .previous\n" \
221 : "=r" (err), "=&r" (v), "=&r" (a) \
222 : "0" (err), "1" (v), "2" (a)); \
223 if (err) \
224 goto fault; \
225 } while (0)
226
227 #define put16_unaligned_check(val,addr) \
228 __put16_unaligned_check("strb",val,addr)
229
230 #define put16t_unaligned_check(val,addr) \
231 __put16_unaligned_check("strbt",val,addr)
232
233 #define __put32_unaligned_check(ins,val,addr) \
234 do { \
235 unsigned int err = 0, v = val, a = addr; \
236 __asm__( FIRST_BYTE_32 \
237 "1: "ins" %1, [%2], #1\n" \
238 " mov %1, %1, "NEXT_BYTE"\n" \
239 "2: "ins" %1, [%2], #1\n" \
240 " mov %1, %1, "NEXT_BYTE"\n" \
241 "3: "ins" %1, [%2], #1\n" \
242 " mov %1, %1, "NEXT_BYTE"\n" \
243 "4: "ins" %1, [%2]\n" \
244 "5:\n" \
245 " .section .fixup,\"ax\"\n" \
246 " .align 2\n" \
247 "6: mov %0, #1\n" \
248 " b 5b\n" \
249 " .previous\n" \
250 " .section __ex_table,\"a\"\n" \
251 " .align 3\n" \
252 " .long 1b, 6b\n" \
253 " .long 2b, 6b\n" \
254 " .long 3b, 6b\n" \
255 " .long 4b, 6b\n" \
256 " .previous\n" \
257 : "=r" (err), "=&r" (v), "=&r" (a) \
258 : "0" (err), "1" (v), "2" (a)); \
259 if (err) \
260 goto fault; \
261 } while (0)
262
263 #define put32_unaligned_check(val,addr) \
264 __put32_unaligned_check("strb", val, addr)
265
266 #define put32t_unaligned_check(val,addr) \
267 __put32_unaligned_check("strbt", val, addr)
268
269 static void
270 do_alignment_finish_ldst(unsigned long addr, unsigned long instr, struct pt_regs *regs, union offset_union offset)
271 {
272 if (!LDST_U_BIT(instr))
273 offset.un = -offset.un;
274
275 if (!LDST_P_BIT(instr))
276 addr += offset.un;
277
278 if (!LDST_P_BIT(instr) || LDST_W_BIT(instr))
279 regs->uregs[RN_BITS(instr)] = addr;
280 }
281
282 static int
283 do_alignment_ldrhstrh(unsigned long addr, unsigned long instr, struct pt_regs *regs)
284 {
285 unsigned int rd = RD_BITS(instr);
286
287 ai_half += 1;
288
289 if (user_mode(regs))
290 goto user;
291
292 if (LDST_L_BIT(instr)) {
293 unsigned long val;
294 get16_unaligned_check(val, addr);
295
296 /* signed half-word? */
297 if (instr & 0x40)
298 val = (signed long)((signed short) val);
299
300 regs->uregs[rd] = val;
301 } else
302 put16_unaligned_check(regs->uregs[rd], addr);
303
304 return TYPE_LDST;
305
306 user:
307 if (LDST_L_BIT(instr)) {
308 unsigned long val;
309 get16t_unaligned_check(val, addr);
310
311 /* signed half-word? */
312 if (instr & 0x40)
313 val = (signed long)((signed short) val);
314
315 regs->uregs[rd] = val;
316 } else
317 put16t_unaligned_check(regs->uregs[rd], addr);
318
319 return TYPE_LDST;
320
321 fault:
322 return TYPE_FAULT;
323 }
324
325 static int
326 do_alignment_ldrdstrd(unsigned long addr, unsigned long instr,
327 struct pt_regs *regs)
328 {
329 unsigned int rd = RD_BITS(instr);
330
331 if (((rd & 1) == 1) || (rd == 14))
332 goto bad;
333
334 ai_dword += 1;
335
336 if (user_mode(regs))
337 goto user;
338
339 if ((instr & 0xf0) == 0xd0) {
340 unsigned long val;
341 get32_unaligned_check(val, addr);
342 regs->uregs[rd] = val;
343 get32_unaligned_check(val, addr + 4);
344 regs->uregs[rd + 1] = val;
345 } else {
346 put32_unaligned_check(regs->uregs[rd], addr);
347 put32_unaligned_check(regs->uregs[rd + 1], addr + 4);
348 }
349
350 return TYPE_LDST;
351
352 user:
353 if ((instr & 0xf0) == 0xd0) {
354 unsigned long val;
355 get32t_unaligned_check(val, addr);
356 regs->uregs[rd] = val;
357 get32t_unaligned_check(val, addr + 4);
358 regs->uregs[rd + 1] = val;
359 } else {
360 put32t_unaligned_check(regs->uregs[rd], addr);
361 put32t_unaligned_check(regs->uregs[rd + 1], addr + 4);
362 }
363
364 return TYPE_LDST;
365 bad:
366 return TYPE_ERROR;
367 fault:
368 return TYPE_FAULT;
369 }
370
371 static int
372 do_alignment_ldrstr(unsigned long addr, unsigned long instr, struct pt_regs *regs)
373 {
374 unsigned int rd = RD_BITS(instr);
375
376 ai_word += 1;
377
378 if ((!LDST_P_BIT(instr) && LDST_W_BIT(instr)) || user_mode(regs))
379 goto trans;
380
381 if (LDST_L_BIT(instr)) {
382 unsigned int val;
383 get32_unaligned_check(val, addr);
384 regs->uregs[rd] = val;
385 } else
386 put32_unaligned_check(regs->uregs[rd], addr);
387 return TYPE_LDST;
388
389 trans:
390 if (LDST_L_BIT(instr)) {
391 unsigned int val;
392 get32t_unaligned_check(val, addr);
393 regs->uregs[rd] = val;
394 } else
395 put32t_unaligned_check(regs->uregs[rd], addr);
396 return TYPE_LDST;
397
398 fault:
399 return TYPE_FAULT;
400 }
401
402 /*
403 * LDM/STM alignment handler.
404 *
405 * There are 4 variants of this instruction:
406 *
407 * B = rn pointer before instruction, A = rn pointer after instruction
408 * ------ increasing address ----->
409 * | | r0 | r1 | ... | rx | |
410 * PU = 01 B A
411 * PU = 11 B A
412 * PU = 00 A B
413 * PU = 10 A B
414 */
415 static int
416 do_alignment_ldmstm(unsigned long addr, unsigned long instr, struct pt_regs *regs)
417 {
418 unsigned int rd, rn, correction, nr_regs, regbits;
419 unsigned long eaddr, newaddr;
420
421 if (LDM_S_BIT(instr))
422 goto bad;
423
424 correction = 4; /* processor implementation defined */
425 regs->ARM_pc += correction;
426
427 ai_multi += 1;
428
429 /* count the number of registers in the mask to be transferred */
430 nr_regs = hweight16(REGMASK_BITS(instr)) * 4;
431
432 rn = RN_BITS(instr);
433 newaddr = eaddr = regs->uregs[rn];
434
435 if (!LDST_U_BIT(instr))
436 nr_regs = -nr_regs;
437 newaddr += nr_regs;
438 if (!LDST_U_BIT(instr))
439 eaddr = newaddr;
440
441 if (LDST_P_EQ_U(instr)) /* U = P */
442 eaddr += 4;
443
444 /*
445 * For alignment faults on the ARM922T/ARM920T the MMU makes
446 * the FSR (and hence addr) equal to the updated base address
447 * of the multiple access rather than the restored value.
448 * Switch this message off if we've got a ARM92[02], otherwise
449 * [ls]dm alignment faults are noisy!
450 */
451 #if !(defined CONFIG_CPU_ARM922T) && !(defined CONFIG_CPU_ARM920T)
452 /*
453 * This is a "hint" - we already have eaddr worked out by the
454 * processor for us.
455 */
456 if (addr != eaddr) {
457 printk(KERN_ERR "LDMSTM: PC = %08lx, instr = %08lx, "
458 "addr = %08lx, eaddr = %08lx\n",
459 instruction_pointer(regs), instr, addr, eaddr);
460 show_regs(regs);
461 }
462 #endif
463
464 if (user_mode(regs)) {
465 for (regbits = REGMASK_BITS(instr), rd = 0; regbits;
466 regbits >>= 1, rd += 1)
467 if (regbits & 1) {
468 if (LDST_L_BIT(instr)) {
469 unsigned int val;
470 get32t_unaligned_check(val, eaddr);
471 regs->uregs[rd] = val;
472 } else
473 put32t_unaligned_check(regs->uregs[rd], eaddr);
474 eaddr += 4;
475 }
476 } else {
477 for (regbits = REGMASK_BITS(instr), rd = 0; regbits;
478 regbits >>= 1, rd += 1)
479 if (regbits & 1) {
480 if (LDST_L_BIT(instr)) {
481 unsigned int val;
482 get32_unaligned_check(val, eaddr);
483 regs->uregs[rd] = val;
484 } else
485 put32_unaligned_check(regs->uregs[rd], eaddr);
486 eaddr += 4;
487 }
488 }
489
490 if (LDST_W_BIT(instr))
491 regs->uregs[rn] = newaddr;
492 if (!LDST_L_BIT(instr) || !(REGMASK_BITS(instr) & (1 << 15)))
493 regs->ARM_pc -= correction;
494 return TYPE_DONE;
495
496 fault:
497 regs->ARM_pc -= correction;
498 return TYPE_FAULT;
499
500 bad:
501 printk(KERN_ERR "Alignment trap: not handling ldm with s-bit set\n");
502 return TYPE_ERROR;
503 }
504
505 /*
506 * Convert Thumb ld/st instruction forms to equivalent ARM instructions so
507 * we can reuse ARM userland alignment fault fixups for Thumb.
508 *
509 * This implementation was initially based on the algorithm found in
510 * gdb/sim/arm/thumbemu.c. It is basically just a code reduction of same
511 * to convert only Thumb ld/st instruction forms to equivalent ARM forms.
512 *
513 * NOTES:
514 * 1. Comments below refer to ARM ARM DDI0100E Thumb Instruction sections.
515 * 2. If for some reason we're passed an non-ld/st Thumb instruction to
516 * decode, we return 0xdeadc0de. This should never happen under normal
517 * circumstances but if it does, we've got other problems to deal with
518 * elsewhere and we obviously can't fix those problems here.
519 */
520
521 static unsigned long
522 thumb2arm(u16 tinstr)
523 {
524 u32 L = (tinstr & (1<<11)) >> 11;
525
526 switch ((tinstr & 0xf800) >> 11) {
527 /* 6.5.1 Format 1: */
528 case 0x6000 >> 11: /* 7.1.52 STR(1) */
529 case 0x6800 >> 11: /* 7.1.26 LDR(1) */
530 case 0x7000 >> 11: /* 7.1.55 STRB(1) */
531 case 0x7800 >> 11: /* 7.1.30 LDRB(1) */
532 return 0xe5800000 |
533 ((tinstr & (1<<12)) << (22-12)) | /* fixup */
534 (L<<20) | /* L==1? */
535 ((tinstr & (7<<0)) << (12-0)) | /* Rd */
536 ((tinstr & (7<<3)) << (16-3)) | /* Rn */
537 ((tinstr & (31<<6)) >> /* immed_5 */
538 (6 - ((tinstr & (1<<12)) ? 0 : 2)));
539 case 0x8000 >> 11: /* 7.1.57 STRH(1) */
540 case 0x8800 >> 11: /* 7.1.32 LDRH(1) */
541 return 0xe1c000b0 |
542 (L<<20) | /* L==1? */
543 ((tinstr & (7<<0)) << (12-0)) | /* Rd */
544 ((tinstr & (7<<3)) << (16-3)) | /* Rn */
545 ((tinstr & (7<<6)) >> (6-1)) | /* immed_5[2:0] */
546 ((tinstr & (3<<9)) >> (9-8)); /* immed_5[4:3] */
547
548 /* 6.5.1 Format 2: */
549 case 0x5000 >> 11:
550 case 0x5800 >> 11:
551 {
552 static const u32 subset[8] = {
553 0xe7800000, /* 7.1.53 STR(2) */
554 0xe18000b0, /* 7.1.58 STRH(2) */
555 0xe7c00000, /* 7.1.56 STRB(2) */
556 0xe19000d0, /* 7.1.34 LDRSB */
557 0xe7900000, /* 7.1.27 LDR(2) */
558 0xe19000b0, /* 7.1.33 LDRH(2) */
559 0xe7d00000, /* 7.1.31 LDRB(2) */
560 0xe19000f0 /* 7.1.35 LDRSH */
561 };
562 return subset[(tinstr & (7<<9)) >> 9] |
563 ((tinstr & (7<<0)) << (12-0)) | /* Rd */
564 ((tinstr & (7<<3)) << (16-3)) | /* Rn */
565 ((tinstr & (7<<6)) >> (6-0)); /* Rm */
566 }
567
568 /* 6.5.1 Format 3: */
569 case 0x4800 >> 11: /* 7.1.28 LDR(3) */
570 /* NOTE: This case is not technically possible. We're
571 * loading 32-bit memory data via PC relative
572 * addressing mode. So we can and should eliminate
573 * this case. But I'll leave it here for now.
574 */
575 return 0xe59f0000 |
576 ((tinstr & (7<<8)) << (12-8)) | /* Rd */
577 ((tinstr & 255) << (2-0)); /* immed_8 */
578
579 /* 6.5.1 Format 4: */
580 case 0x9000 >> 11: /* 7.1.54 STR(3) */
581 case 0x9800 >> 11: /* 7.1.29 LDR(4) */
582 return 0xe58d0000 |
583 (L<<20) | /* L==1? */
584 ((tinstr & (7<<8)) << (12-8)) | /* Rd */
585 ((tinstr & 255) << 2); /* immed_8 */
586
587 /* 6.6.1 Format 1: */
588 case 0xc000 >> 11: /* 7.1.51 STMIA */
589 case 0xc800 >> 11: /* 7.1.25 LDMIA */
590 {
591 u32 Rn = (tinstr & (7<<8)) >> 8;
592 u32 W = ((L<<Rn) & (tinstr&255)) ? 0 : 1<<21;
593
594 return 0xe8800000 | W | (L<<20) | (Rn<<16) |
595 (tinstr&255);
596 }
597
598 /* 6.6.1 Format 2: */
599 case 0xb000 >> 11: /* 7.1.48 PUSH */
600 case 0xb800 >> 11: /* 7.1.47 POP */
601 if ((tinstr & (3 << 9)) == 0x0400) {
602 static const u32 subset[4] = {
603 0xe92d0000, /* STMDB sp!,{registers} */
604 0xe92d4000, /* STMDB sp!,{registers,lr} */
605 0xe8bd0000, /* LDMIA sp!,{registers} */
606 0xe8bd8000 /* LDMIA sp!,{registers,pc} */
607 };
608 return subset[(L<<1) | ((tinstr & (1<<8)) >> 8)] |
609 (tinstr & 255); /* register_list */
610 }
611 /* Else fall through for illegal instruction case */
612
613 default:
614 return 0xdeadc0de;
615 }
616 }
617
618 static int
619 do_alignment(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
620 {
621 union offset_union offset;
622 unsigned long instr = 0, instrptr;
623 int (*handler)(unsigned long addr, unsigned long instr, struct pt_regs *regs);
624 unsigned int type;
625 mm_segment_t fs;
626 unsigned int fault;
627 u16 tinstr = 0;
628
629 instrptr = instruction_pointer(regs);
630
631 fs = get_fs();
632 set_fs(KERNEL_DS);
633 if thumb_mode(regs) {
634 fault = __get_user(tinstr, (u16 *)(instrptr & ~1));
635 if (!(fault))
636 instr = thumb2arm(tinstr);
637 } else
638 fault = __get_user(instr, (u32 *)instrptr);
639 set_fs(fs);
640
641 if (fault) {
642 type = TYPE_FAULT;
643 goto bad_or_fault;
644 }
645
646 if (user_mode(regs))
647 goto user;
648
649 ai_sys += 1;
650
651 fixup:
652
653 regs->ARM_pc += thumb_mode(regs) ? 2 : 4;
654
655 switch (CODING_BITS(instr)) {
656 case 0x00000000: /* 3.13.4 load/store instruction extensions */
657 if (LDSTHD_I_BIT(instr))
658 offset.un = (instr & 0xf00) >> 4 | (instr & 15);
659 else
660 offset.un = regs->uregs[RM_BITS(instr)];
661
662 if ((instr & 0x000000f0) == 0x000000b0 || /* LDRH, STRH */
663 (instr & 0x001000f0) == 0x001000f0) /* LDRSH */
664 handler = do_alignment_ldrhstrh;
665 else if ((instr & 0x001000f0) == 0x000000d0 || /* LDRD */
666 (instr & 0x001000f0) == 0x000000f0) /* STRD */
667 handler = do_alignment_ldrdstrd;
668 else if ((instr & 0x01f00ff0) == 0x01000090) /* SWP */
669 goto swp;
670 else
671 goto bad;
672 break;
673
674 case 0x04000000: /* ldr or str immediate */
675 offset.un = OFFSET_BITS(instr);
676 handler = do_alignment_ldrstr;
677 break;
678
679 case 0x06000000: /* ldr or str register */
680 offset.un = regs->uregs[RM_BITS(instr)];
681
682 if (IS_SHIFT(instr)) {
683 unsigned int shiftval = SHIFT_BITS(instr);
684
685 switch(SHIFT_TYPE(instr)) {
686 case SHIFT_LSL:
687 offset.un <<= shiftval;
688 break;
689
690 case SHIFT_LSR:
691 offset.un >>= shiftval;
692 break;
693
694 case SHIFT_ASR:
695 offset.sn >>= shiftval;
696 break;
697
698 case SHIFT_RORRRX:
699 if (shiftval == 0) {
700 offset.un >>= 1;
701 if (regs->ARM_cpsr & PSR_C_BIT)
702 offset.un |= 1 << 31;
703 } else
704 offset.un = offset.un >> shiftval |
705 offset.un << (32 - shiftval);
706 break;
707 }
708 }
709 handler = do_alignment_ldrstr;
710 break;
711
712 case 0x08000000: /* ldm or stm */
713 handler = do_alignment_ldmstm;
714 break;
715
716 default:
717 goto bad;
718 }
719
720 type = handler(addr, instr, regs);
721
722 if (type == TYPE_ERROR || type == TYPE_FAULT)
723 goto bad_or_fault;
724
725 if (type == TYPE_LDST)
726 do_alignment_finish_ldst(addr, instr, regs, offset);
727
728 return 0;
729
730 bad_or_fault:
731 if (type == TYPE_ERROR)
732 goto bad;
733 regs->ARM_pc -= thumb_mode(regs) ? 2 : 4;
734 /*
735 * We got a fault - fix it up, or die.
736 */
737 do_bad_area(addr, fsr, regs);
738 return 0;
739
740 swp:
741 printk(KERN_ERR "Alignment trap: not handling swp instruction\n");
742
743 bad:
744 /*
745 * Oops, we didn't handle the instruction.
746 */
747 printk(KERN_ERR "Alignment trap: not handling instruction "
748 "%0*lx at [<%08lx>]\n",
749 thumb_mode(regs) ? 4 : 8,
750 thumb_mode(regs) ? tinstr : instr, instrptr);
751 ai_skipped += 1;
752 return 1;
753
754 user:
755 ai_user += 1;
756
757 if (ai_usermode & 1)
758 printk("Alignment trap: %s (%d) PC=0x%08lx Instr=0x%0*lx "
759 "Address=0x%08lx FSR 0x%03x\n", current->comm,
760 current->pid, instrptr,
761 thumb_mode(regs) ? 4 : 8,
762 thumb_mode(regs) ? tinstr : instr,
763 addr, fsr);
764
765 if (ai_usermode & 2)
766 goto fixup;
767
768 if (ai_usermode & 4)
769 force_sig(SIGBUS, current);
770 else
771 set_cr(cr_no_alignment);
772
773 return 0;
774 }
775
776 /*
777 * This needs to be done after sysctl_init, otherwise sys/ will be
778 * overwritten. Actually, this shouldn't be in sys/ at all since
779 * it isn't a sysctl, and it doesn't contain sysctl information.
780 * We now locate it in /proc/cpu/alignment instead.
781 */
782 static int __init alignment_init(void)
783 {
784 #ifdef CONFIG_PROC_FS
785 struct proc_dir_entry *res;
786
787 res = proc_mkdir("cpu", NULL);
788 if (!res)
789 return -ENOMEM;
790
791 res = create_proc_entry("alignment", S_IWUSR | S_IRUGO, res);
792 if (!res)
793 return -ENOMEM;
794
795 res->read_proc = proc_alignment_read;
796 res->write_proc = proc_alignment_write;
797 #endif
798
799 hook_fault_code(1, do_alignment, SIGILL, "alignment exception");
800 hook_fault_code(3, do_alignment, SIGILL, "alignment exception");
801
802 return 0;
803 }
804
805 fs_initcall(alignment_init);
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