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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
29#include "fault.h"
30
31/*
32 * 32-bit misaligned trap handler (c) 1998 San Mehat (CCC) -July 1998
33 * /proc/sys/debug/alignment, modified and integrated into
34 * Linux 2.1 by Russell King
35 *
36 * Speed optimisations and better fault handling by Russell King.
37 *
38 * *** NOTE ***
39 * This code is not portable to processors with late data abort handling.
40 */
41#define CODING_BITS(i) (i & 0x0e000000)
42
43#define LDST_I_BIT(i) (i & (1 << 26)) /* Immediate constant */
44#define LDST_P_BIT(i) (i & (1 << 24)) /* Preindex */
45#define LDST_U_BIT(i) (i & (1 << 23)) /* Add offset */
46#define LDST_W_BIT(i) (i & (1 << 21)) /* Writeback */
47#define LDST_L_BIT(i) (i & (1 << 20)) /* Load */
48
49#define LDST_P_EQ_U(i) ((((i) ^ ((i) >> 1)) & (1 << 23)) == 0)
50
51#define LDSTHD_I_BIT(i) (i & (1 << 22)) /* double/half-word immed */
52#define LDM_S_BIT(i) (i & (1 << 22)) /* write CPSR from SPSR */
53
54#define RN_BITS(i) ((i >> 16) & 15) /* Rn */
55#define RD_BITS(i) ((i >> 12) & 15) /* Rd */
56#define RM_BITS(i) (i & 15) /* Rm */
57
58#define REGMASK_BITS(i) (i & 0xffff)
59#define OFFSET_BITS(i) (i & 0x0fff)
60
61#define IS_SHIFT(i) (i & 0x0ff0)
62#define SHIFT_BITS(i) ((i >> 7) & 0x1f)
63#define SHIFT_TYPE(i) (i & 0x60)
64#define SHIFT_LSL 0x00
65#define SHIFT_LSR 0x20
66#define SHIFT_ASR 0x40
67#define SHIFT_RORRRX 0x60
68
69#define BAD_INSTR 0xdeadc0de
70
71/* Thumb-2 32 bit format per ARMv7 DDI0406A A6.3, either f800h,e800h,f800h */
72#define IS_T32(hi16) \
73 (((hi16) & 0xe000) == 0xe000 && ((hi16) & 0x1800))
74
75static unsigned long ai_user;
76static unsigned long ai_sys;
77static unsigned long ai_skipped;
78static unsigned long ai_half;
79static unsigned long ai_word;
80static unsigned long ai_dword;
81static unsigned long ai_multi;
82static int ai_usermode;
83
84core_param(alignment, ai_usermode, int, 0600);
85
86#define UM_WARN (1 << 0)
87#define UM_FIXUP (1 << 1)
88#define UM_SIGNAL (1 << 2)
89
90/* Return true if and only if the ARMv6 unaligned access model is in use. */
91static bool cpu_is_v6_unaligned(void)
92{
93 return cpu_architecture() >= CPU_ARCH_ARMv6 && (cr_alignment & CR_U);
94}
95
96static int safe_usermode(int new_usermode, bool warn)
97{
98 /*
99 * ARMv6 and later CPUs can perform unaligned accesses for
100 * most single load and store instructions up to word size.
101 * LDM, STM, LDRD and STRD still need to be handled.
102 *
103 * Ignoring the alignment fault is not an option on these
104 * CPUs since we spin re-faulting the instruction without
105 * making any progress.
106 */
107 if (cpu_is_v6_unaligned() && !(new_usermode & (UM_FIXUP | UM_SIGNAL))) {
108 new_usermode |= UM_FIXUP;
109
110 if (warn)
111 printk(KERN_WARNING "alignment: ignoring faults is unsafe on this CPU. Defaulting to fixup mode.\n");
112 }
113
114 return new_usermode;
115}
116
117#ifdef CONFIG_PROC_FS
118static const char *usermode_action[] = {
119 "ignored",
120 "warn",
121 "fixup",
122 "fixup+warn",
123 "signal",
124 "signal+warn"
125};
126
127static int alignment_proc_show(struct seq_file *m, void *v)
128{
129 seq_printf(m, "User:\t\t%lu\n", ai_user);
130 seq_printf(m, "System:\t\t%lu\n", ai_sys);
131 seq_printf(m, "Skipped:\t%lu\n", ai_skipped);
132 seq_printf(m, "Half:\t\t%lu\n", ai_half);
133 seq_printf(m, "Word:\t\t%lu\n", ai_word);
134 if (cpu_architecture() >= CPU_ARCH_ARMv5TE)
135 seq_printf(m, "DWord:\t\t%lu\n", ai_dword);
136 seq_printf(m, "Multi:\t\t%lu\n", ai_multi);
137 seq_printf(m, "User faults:\t%i (%s)\n", ai_usermode,
138 usermode_action[ai_usermode]);
139
140 return 0;
141}
142
143static int alignment_proc_open(struct inode *inode, struct file *file)
144{
145 return single_open(file, alignment_proc_show, NULL);
146}
147
148static ssize_t alignment_proc_write(struct file *file, const char __user *buffer,
149 size_t count, loff_t *pos)
150{
151 char mode;
152
153 if (count > 0) {
154 if (get_user(mode, buffer))
155 return -EFAULT;
156 if (mode >= '0' && mode <= '5')
157 ai_usermode = safe_usermode(mode - '0', true);
158 }
159 return count;
160}
161
162static const struct file_operations alignment_proc_fops = {
163 .open = alignment_proc_open,
164 .read = seq_read,
165 .llseek = seq_lseek,
166 .release = single_release,
167 .write = alignment_proc_write,
168};
169#endif /* CONFIG_PROC_FS */
170
171union offset_union {
172 unsigned long un;
173 signed long sn;
174};
175
176#define TYPE_ERROR 0
177#define TYPE_FAULT 1
178#define TYPE_LDST 2
179#define TYPE_DONE 3
180
181#ifdef __ARMEB__
182#define BE 1
183#define FIRST_BYTE_16 "mov %1, %1, ror #8\n"
184#define FIRST_BYTE_32 "mov %1, %1, ror #24\n"
185#define NEXT_BYTE "ror #24"
186#else
187#define BE 0
188#define FIRST_BYTE_16
189#define FIRST_BYTE_32
190#define NEXT_BYTE "lsr #8"
191#endif
192
193#define __get8_unaligned_check(ins,val,addr,err) \
194 __asm__( \
195 ARM( "1: "ins" %1, [%2], #1\n" ) \
196 THUMB( "1: "ins" %1, [%2]\n" ) \
197 THUMB( " add %2, %2, #1\n" ) \
198 "2:\n" \
199 " .pushsection .fixup,\"ax\"\n" \
200 " .align 2\n" \
201 "3: mov %0, #1\n" \
202 " b 2b\n" \
203 " .popsection\n" \
204 " .pushsection __ex_table,\"a\"\n" \
205 " .align 3\n" \
206 " .long 1b, 3b\n" \
207 " .popsection\n" \
208 : "=r" (err), "=&r" (val), "=r" (addr) \
209 : "0" (err), "2" (addr))
210
211#define __get16_unaligned_check(ins,val,addr) \
212 do { \
213 unsigned int err = 0, v, a = addr; \
214 __get8_unaligned_check(ins,v,a,err); \
215 val = v << ((BE) ? 8 : 0); \
216 __get8_unaligned_check(ins,v,a,err); \
217 val |= v << ((BE) ? 0 : 8); \
218 if (err) \
219 goto fault; \
220 } while (0)
221
222#define get16_unaligned_check(val,addr) \
223 __get16_unaligned_check("ldrb",val,addr)
224
225#define get16t_unaligned_check(val,addr) \
226 __get16_unaligned_check("ldrbt",val,addr)
227
228#define __get32_unaligned_check(ins,val,addr) \
229 do { \
230 unsigned int err = 0, v, a = addr; \
231 __get8_unaligned_check(ins,v,a,err); \
232 val = v << ((BE) ? 24 : 0); \
233 __get8_unaligned_check(ins,v,a,err); \
234 val |= v << ((BE) ? 16 : 8); \
235 __get8_unaligned_check(ins,v,a,err); \
236 val |= v << ((BE) ? 8 : 16); \
237 __get8_unaligned_check(ins,v,a,err); \
238 val |= v << ((BE) ? 0 : 24); \
239 if (err) \
240 goto fault; \
241 } while (0)
242
243#define get32_unaligned_check(val,addr) \
244 __get32_unaligned_check("ldrb",val,addr)
245
246#define get32t_unaligned_check(val,addr) \
247 __get32_unaligned_check("ldrbt",val,addr)
248
249#define __put16_unaligned_check(ins,val,addr) \
250 do { \
251 unsigned int err = 0, v = val, a = addr; \
252 __asm__( FIRST_BYTE_16 \
253 ARM( "1: "ins" %1, [%2], #1\n" ) \
254 THUMB( "1: "ins" %1, [%2]\n" ) \
255 THUMB( " add %2, %2, #1\n" ) \
256 " mov %1, %1, "NEXT_BYTE"\n" \
257 "2: "ins" %1, [%2]\n" \
258 "3:\n" \
259 " .pushsection .fixup,\"ax\"\n" \
260 " .align 2\n" \
261 "4: mov %0, #1\n" \
262 " b 3b\n" \
263 " .popsection\n" \
264 " .pushsection __ex_table,\"a\"\n" \
265 " .align 3\n" \
266 " .long 1b, 4b\n" \
267 " .long 2b, 4b\n" \
268 " .popsection\n" \
269 : "=r" (err), "=&r" (v), "=&r" (a) \
270 : "0" (err), "1" (v), "2" (a)); \
271 if (err) \
272 goto fault; \
273 } while (0)
274
275#define put16_unaligned_check(val,addr) \
276 __put16_unaligned_check("strb",val,addr)
277
278#define put16t_unaligned_check(val,addr) \
279 __put16_unaligned_check("strbt",val,addr)
280
281#define __put32_unaligned_check(ins,val,addr) \
282 do { \
283 unsigned int err = 0, v = val, a = addr; \
284 __asm__( FIRST_BYTE_32 \
285 ARM( "1: "ins" %1, [%2], #1\n" ) \
286 THUMB( "1: "ins" %1, [%2]\n" ) \
287 THUMB( " add %2, %2, #1\n" ) \
288 " mov %1, %1, "NEXT_BYTE"\n" \
289 ARM( "2: "ins" %1, [%2], #1\n" ) \
290 THUMB( "2: "ins" %1, [%2]\n" ) \
291 THUMB( " add %2, %2, #1\n" ) \
292 " mov %1, %1, "NEXT_BYTE"\n" \
293 ARM( "3: "ins" %1, [%2], #1\n" ) \
294 THUMB( "3: "ins" %1, [%2]\n" ) \
295 THUMB( " add %2, %2, #1\n" ) \
296 " mov %1, %1, "NEXT_BYTE"\n" \
297 "4: "ins" %1, [%2]\n" \
298 "5:\n" \
299 " .pushsection .fixup,\"ax\"\n" \
300 " .align 2\n" \
301 "6: mov %0, #1\n" \
302 " b 5b\n" \
303 " .popsection\n" \
304 " .pushsection __ex_table,\"a\"\n" \
305 " .align 3\n" \
306 " .long 1b, 6b\n" \
307 " .long 2b, 6b\n" \
308 " .long 3b, 6b\n" \
309 " .long 4b, 6b\n" \
310 " .popsection\n" \
311 : "=r" (err), "=&r" (v), "=&r" (a) \
312 : "0" (err), "1" (v), "2" (a)); \
313 if (err) \
314 goto fault; \
315 } while (0)
316
317#define put32_unaligned_check(val,addr) \
318 __put32_unaligned_check("strb", val, addr)
319
320#define put32t_unaligned_check(val,addr) \
321 __put32_unaligned_check("strbt", val, addr)
322
323static void
324do_alignment_finish_ldst(unsigned long addr, unsigned long instr, struct pt_regs *regs, union offset_union offset)
325{
326 if (!LDST_U_BIT(instr))
327 offset.un = -offset.un;
328
329 if (!LDST_P_BIT(instr))
330 addr += offset.un;
331
332 if (!LDST_P_BIT(instr) || LDST_W_BIT(instr))
333 regs->uregs[RN_BITS(instr)] = addr;
334}
335
336static int
337do_alignment_ldrhstrh(unsigned long addr, unsigned long instr, struct pt_regs *regs)
338{
339 unsigned int rd = RD_BITS(instr);
340
341 ai_half += 1;
342
343 if (user_mode(regs))
344 goto user;
345
346 if (LDST_L_BIT(instr)) {
347 unsigned long val;
348 get16_unaligned_check(val, addr);
349
350 /* signed half-word? */
351 if (instr & 0x40)
352 val = (signed long)((signed short) val);
353
354 regs->uregs[rd] = val;
355 } else
356 put16_unaligned_check(regs->uregs[rd], addr);
357
358 return TYPE_LDST;
359
360 user:
361 if (LDST_L_BIT(instr)) {
362 unsigned long val;
363 get16t_unaligned_check(val, addr);
364
365 /* signed half-word? */
366 if (instr & 0x40)
367 val = (signed long)((signed short) val);
368
369 regs->uregs[rd] = val;
370 } else
371 put16t_unaligned_check(regs->uregs[rd], addr);
372
373 return TYPE_LDST;
374
375 fault:
376 return TYPE_FAULT;
377}
378
379static int
380do_alignment_ldrdstrd(unsigned long addr, unsigned long instr,
381 struct pt_regs *regs)
382{
383 unsigned int rd = RD_BITS(instr);
384 unsigned int rd2;
385 int load;
386
387 if ((instr & 0xfe000000) == 0xe8000000) {
388 /* ARMv7 Thumb-2 32-bit LDRD/STRD */
389 rd2 = (instr >> 8) & 0xf;
390 load = !!(LDST_L_BIT(instr));
391 } else if (((rd & 1) == 1) || (rd == 14))
392 goto bad;
393 else {
394 load = ((instr & 0xf0) == 0xd0);
395 rd2 = rd + 1;
396 }
397
398 ai_dword += 1;
399
400 if (user_mode(regs))
401 goto user;
402
403 if (load) {
404 unsigned long val;
405 get32_unaligned_check(val, addr);
406 regs->uregs[rd] = val;
407 get32_unaligned_check(val, addr + 4);
408 regs->uregs[rd2] = val;
409 } else {
410 put32_unaligned_check(regs->uregs[rd], addr);
411 put32_unaligned_check(regs->uregs[rd2], addr + 4);
412 }
413
414 return TYPE_LDST;
415
416 user:
417 if (load) {
418 unsigned long val;
419 get32t_unaligned_check(val, addr);
420 regs->uregs[rd] = val;
421 get32t_unaligned_check(val, addr + 4);
422 regs->uregs[rd2] = val;
423 } else {
424 put32t_unaligned_check(regs->uregs[rd], addr);
425 put32t_unaligned_check(regs->uregs[rd2], addr + 4);
426 }
427
428 return TYPE_LDST;
429 bad:
430 return TYPE_ERROR;
431 fault:
432 return TYPE_FAULT;
433}
434
435static int
436do_alignment_ldrstr(unsigned long addr, unsigned long instr, struct pt_regs *regs)
437{
438 unsigned int rd = RD_BITS(instr);
439
440 ai_word += 1;
441
442 if ((!LDST_P_BIT(instr) && LDST_W_BIT(instr)) || user_mode(regs))
443 goto trans;
444
445 if (LDST_L_BIT(instr)) {
446 unsigned int val;
447 get32_unaligned_check(val, addr);
448 regs->uregs[rd] = val;
449 } else
450 put32_unaligned_check(regs->uregs[rd], addr);
451 return TYPE_LDST;
452
453 trans:
454 if (LDST_L_BIT(instr)) {
455 unsigned int val;
456 get32t_unaligned_check(val, addr);
457 regs->uregs[rd] = val;
458 } else
459 put32t_unaligned_check(regs->uregs[rd], addr);
460 return TYPE_LDST;
461
462 fault:
463 return TYPE_FAULT;
464}
465
466/*
467 * LDM/STM alignment handler.
468 *
469 * There are 4 variants of this instruction:
470 *
471 * B = rn pointer before instruction, A = rn pointer after instruction
472 * ------ increasing address ----->
473 * | | r0 | r1 | ... | rx | |
474 * PU = 01 B A
475 * PU = 11 B A
476 * PU = 00 A B
477 * PU = 10 A B
478 */
479static int
480do_alignment_ldmstm(unsigned long addr, unsigned long instr, struct pt_regs *regs)
481{
482 unsigned int rd, rn, correction, nr_regs, regbits;
483 unsigned long eaddr, newaddr;
484
485 if (LDM_S_BIT(instr))
486 goto bad;
487
488 correction = 4; /* processor implementation defined */
489 regs->ARM_pc += correction;
490
491 ai_multi += 1;
492
493 /* count the number of registers in the mask to be transferred */
494 nr_regs = hweight16(REGMASK_BITS(instr)) * 4;
495
496 rn = RN_BITS(instr);
497 newaddr = eaddr = regs->uregs[rn];
498
499 if (!LDST_U_BIT(instr))
500 nr_regs = -nr_regs;
501 newaddr += nr_regs;
502 if (!LDST_U_BIT(instr))
503 eaddr = newaddr;
504
505 if (LDST_P_EQ_U(instr)) /* U = P */
506 eaddr += 4;
507
508 /*
509 * For alignment faults on the ARM922T/ARM920T the MMU makes
510 * the FSR (and hence addr) equal to the updated base address
511 * of the multiple access rather than the restored value.
512 * Switch this message off if we've got a ARM92[02], otherwise
513 * [ls]dm alignment faults are noisy!
514 */
515#if !(defined CONFIG_CPU_ARM922T) && !(defined CONFIG_CPU_ARM920T)
516 /*
517 * This is a "hint" - we already have eaddr worked out by the
518 * processor for us.
519 */
520 if (addr != eaddr) {
521 printk(KERN_ERR "LDMSTM: PC = %08lx, instr = %08lx, "
522 "addr = %08lx, eaddr = %08lx\n",
523 instruction_pointer(regs), instr, addr, eaddr);
524 show_regs(regs);
525 }
526#endif
527
528 if (user_mode(regs)) {
529 for (regbits = REGMASK_BITS(instr), rd = 0; regbits;
530 regbits >>= 1, rd += 1)
531 if (regbits & 1) {
532 if (LDST_L_BIT(instr)) {
533 unsigned int val;
534 get32t_unaligned_check(val, eaddr);
535 regs->uregs[rd] = val;
536 } else
537 put32t_unaligned_check(regs->uregs[rd], eaddr);
538 eaddr += 4;
539 }
540 } else {
541 for (regbits = REGMASK_BITS(instr), rd = 0; regbits;
542 regbits >>= 1, rd += 1)
543 if (regbits & 1) {
544 if (LDST_L_BIT(instr)) {
545 unsigned int val;
546 get32_unaligned_check(val, eaddr);
547 regs->uregs[rd] = val;
548 } else
549 put32_unaligned_check(regs->uregs[rd], eaddr);
550 eaddr += 4;
551 }
552 }
553
554 if (LDST_W_BIT(instr))
555 regs->uregs[rn] = newaddr;
556 if (!LDST_L_BIT(instr) || !(REGMASK_BITS(instr) & (1 << 15)))
557 regs->ARM_pc -= correction;
558 return TYPE_DONE;
559
560fault:
561 regs->ARM_pc -= correction;
562 return TYPE_FAULT;
563
564bad:
565 printk(KERN_ERR "Alignment trap: not handling ldm with s-bit set\n");
566 return TYPE_ERROR;
567}
568
569/*
570 * Convert Thumb ld/st instruction forms to equivalent ARM instructions so
571 * we can reuse ARM userland alignment fault fixups for Thumb.
572 *
573 * This implementation was initially based on the algorithm found in
574 * gdb/sim/arm/thumbemu.c. It is basically just a code reduction of same
575 * to convert only Thumb ld/st instruction forms to equivalent ARM forms.
576 *
577 * NOTES:
578 * 1. Comments below refer to ARM ARM DDI0100E Thumb Instruction sections.
579 * 2. If for some reason we're passed an non-ld/st Thumb instruction to
580 * decode, we return 0xdeadc0de. This should never happen under normal
581 * circumstances but if it does, we've got other problems to deal with
582 * elsewhere and we obviously can't fix those problems here.
583 */
584
585static unsigned long
586thumb2arm(u16 tinstr)
587{
588 u32 L = (tinstr & (1<<11)) >> 11;
589
590 switch ((tinstr & 0xf800) >> 11) {
591 /* 6.5.1 Format 1: */
592 case 0x6000 >> 11: /* 7.1.52 STR(1) */
593 case 0x6800 >> 11: /* 7.1.26 LDR(1) */
594 case 0x7000 >> 11: /* 7.1.55 STRB(1) */
595 case 0x7800 >> 11: /* 7.1.30 LDRB(1) */
596 return 0xe5800000 |
597 ((tinstr & (1<<12)) << (22-12)) | /* fixup */
598 (L<<20) | /* L==1? */
599 ((tinstr & (7<<0)) << (12-0)) | /* Rd */
600 ((tinstr & (7<<3)) << (16-3)) | /* Rn */
601 ((tinstr & (31<<6)) >> /* immed_5 */
602 (6 - ((tinstr & (1<<12)) ? 0 : 2)));
603 case 0x8000 >> 11: /* 7.1.57 STRH(1) */
604 case 0x8800 >> 11: /* 7.1.32 LDRH(1) */
605 return 0xe1c000b0 |
606 (L<<20) | /* L==1? */
607 ((tinstr & (7<<0)) << (12-0)) | /* Rd */
608 ((tinstr & (7<<3)) << (16-3)) | /* Rn */
609 ((tinstr & (7<<6)) >> (6-1)) | /* immed_5[2:0] */
610 ((tinstr & (3<<9)) >> (9-8)); /* immed_5[4:3] */
611
612 /* 6.5.1 Format 2: */
613 case 0x5000 >> 11:
614 case 0x5800 >> 11:
615 {
616 static const u32 subset[8] = {
617 0xe7800000, /* 7.1.53 STR(2) */
618 0xe18000b0, /* 7.1.58 STRH(2) */
619 0xe7c00000, /* 7.1.56 STRB(2) */
620 0xe19000d0, /* 7.1.34 LDRSB */
621 0xe7900000, /* 7.1.27 LDR(2) */
622 0xe19000b0, /* 7.1.33 LDRH(2) */
623 0xe7d00000, /* 7.1.31 LDRB(2) */
624 0xe19000f0 /* 7.1.35 LDRSH */
625 };
626 return subset[(tinstr & (7<<9)) >> 9] |
627 ((tinstr & (7<<0)) << (12-0)) | /* Rd */
628 ((tinstr & (7<<3)) << (16-3)) | /* Rn */
629 ((tinstr & (7<<6)) >> (6-0)); /* Rm */
630 }
631
632 /* 6.5.1 Format 3: */
633 case 0x4800 >> 11: /* 7.1.28 LDR(3) */
634 /* NOTE: This case is not technically possible. We're
635 * loading 32-bit memory data via PC relative
636 * addressing mode. So we can and should eliminate
637 * this case. But I'll leave it here for now.
638 */
639 return 0xe59f0000 |
640 ((tinstr & (7<<8)) << (12-8)) | /* Rd */
641 ((tinstr & 255) << (2-0)); /* immed_8 */
642
643 /* 6.5.1 Format 4: */
644 case 0x9000 >> 11: /* 7.1.54 STR(3) */
645 case 0x9800 >> 11: /* 7.1.29 LDR(4) */
646 return 0xe58d0000 |
647 (L<<20) | /* L==1? */
648 ((tinstr & (7<<8)) << (12-8)) | /* Rd */
649 ((tinstr & 255) << 2); /* immed_8 */
650
651 /* 6.6.1 Format 1: */
652 case 0xc000 >> 11: /* 7.1.51 STMIA */
653 case 0xc800 >> 11: /* 7.1.25 LDMIA */
654 {
655 u32 Rn = (tinstr & (7<<8)) >> 8;
656 u32 W = ((L<<Rn) & (tinstr&255)) ? 0 : 1<<21;
657
658 return 0xe8800000 | W | (L<<20) | (Rn<<16) |
659 (tinstr&255);
660 }
661
662 /* 6.6.1 Format 2: */
663 case 0xb000 >> 11: /* 7.1.48 PUSH */
664 case 0xb800 >> 11: /* 7.1.47 POP */
665 if ((tinstr & (3 << 9)) == 0x0400) {
666 static const u32 subset[4] = {
667 0xe92d0000, /* STMDB sp!,{registers} */
668 0xe92d4000, /* STMDB sp!,{registers,lr} */
669 0xe8bd0000, /* LDMIA sp!,{registers} */
670 0xe8bd8000 /* LDMIA sp!,{registers,pc} */
671 };
672 return subset[(L<<1) | ((tinstr & (1<<8)) >> 8)] |
673 (tinstr & 255); /* register_list */
674 }
675 /* Else fall through for illegal instruction case */
676
677 default:
678 return BAD_INSTR;
679 }
680}
681
682/*
683 * Convert Thumb-2 32 bit LDM, STM, LDRD, STRD to equivalent instruction
684 * handlable by ARM alignment handler, also find the corresponding handler,
685 * so that we can reuse ARM userland alignment fault fixups for Thumb.
686 *
687 * @pinstr: original Thumb-2 instruction; returns new handlable instruction
688 * @regs: register context.
689 * @poffset: return offset from faulted addr for later writeback
690 *
691 * NOTES:
692 * 1. Comments below refer to ARMv7 DDI0406A Thumb Instruction sections.
693 * 2. Register name Rt from ARMv7 is same as Rd from ARMv6 (Rd is Rt)
694 */
695static void *
696do_alignment_t32_to_handler(unsigned long *pinstr, struct pt_regs *regs,
697 union offset_union *poffset)
698{
699 unsigned long instr = *pinstr;
700 u16 tinst1 = (instr >> 16) & 0xffff;
701 u16 tinst2 = instr & 0xffff;
702 poffset->un = 0;
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
746static int
747do_alignment(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
748{
749 union offset_union 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 mm_segment_t fs;
754 unsigned int fault;
755 u16 tinstr = 0;
756 int isize = 4;
757 int thumb2_32b = 0;
758
759 if (interrupts_enabled(regs))
760 local_irq_enable();
761
762 instrptr = instruction_pointer(regs);
763
764 fs = get_fs();
765 set_fs(KERNEL_DS);
766 if (thumb_mode(regs)) {
767 fault = __get_user(tinstr, (u16 *)(instrptr & ~1));
768 if (!fault) {
769 if (cpu_architecture() >= CPU_ARCH_ARMv7 &&
770 IS_T32(tinstr)) {
771 /* Thumb-2 32-bit */
772 u16 tinst2 = 0;
773 fault = __get_user(tinst2, (u16 *)(instrptr+2));
774 instr = (tinstr << 16) | tinst2;
775 thumb2_32b = 1;
776 } else {
777 isize = 2;
778 instr = thumb2arm(tinstr);
779 }
780 }
781 } else
782 fault = __get_user(instr, (u32 *)instrptr);
783 set_fs(fs);
784
785 if (fault) {
786 type = TYPE_FAULT;
787 goto bad_or_fault;
788 }
789
790 if (user_mode(regs))
791 goto user;
792
793 ai_sys += 1;
794
795 fixup:
796
797 regs->ARM_pc += isize;
798
799 switch (CODING_BITS(instr)) {
800 case 0x00000000: /* 3.13.4 load/store instruction extensions */
801 if (LDSTHD_I_BIT(instr))
802 offset.un = (instr & 0xf00) >> 4 | (instr & 15);
803 else
804 offset.un = regs->uregs[RM_BITS(instr)];
805
806 if ((instr & 0x000000f0) == 0x000000b0 || /* LDRH, STRH */
807 (instr & 0x001000f0) == 0x001000f0) /* LDRSH */
808 handler = do_alignment_ldrhstrh;
809 else if ((instr & 0x001000f0) == 0x000000d0 || /* LDRD */
810 (instr & 0x001000f0) == 0x000000f0) /* STRD */
811 handler = do_alignment_ldrdstrd;
812 else if ((instr & 0x01f00ff0) == 0x01000090) /* SWP */
813 goto swp;
814 else
815 goto bad;
816 break;
817
818 case 0x04000000: /* ldr or str immediate */
819 offset.un = OFFSET_BITS(instr);
820 handler = do_alignment_ldrstr;
821 break;
822
823 case 0x06000000: /* ldr or str register */
824 offset.un = regs->uregs[RM_BITS(instr)];
825
826 if (IS_SHIFT(instr)) {
827 unsigned int shiftval = SHIFT_BITS(instr);
828
829 switch(SHIFT_TYPE(instr)) {
830 case SHIFT_LSL:
831 offset.un <<= shiftval;
832 break;
833
834 case SHIFT_LSR:
835 offset.un >>= shiftval;
836 break;
837
838 case SHIFT_ASR:
839 offset.sn >>= shiftval;
840 break;
841
842 case SHIFT_RORRRX:
843 if (shiftval == 0) {
844 offset.un >>= 1;
845 if (regs->ARM_cpsr & PSR_C_BIT)
846 offset.un |= 1 << 31;
847 } else
848 offset.un = offset.un >> shiftval |
849 offset.un << (32 - shiftval);
850 break;
851 }
852 }
853 handler = do_alignment_ldrstr;
854 break;
855
856 case 0x08000000: /* ldm or stm, or thumb-2 32bit instruction */
857 if (thumb2_32b)
858 handler = do_alignment_t32_to_handler(&instr, regs, &offset);
859 else
860 handler = do_alignment_ldmstm;
861 break;
862
863 default:
864 goto bad;
865 }
866
867 if (!handler)
868 goto bad;
869 type = handler(addr, instr, regs);
870
871 if (type == TYPE_ERROR || type == TYPE_FAULT) {
872 regs->ARM_pc -= isize;
873 goto bad_or_fault;
874 }
875
876 if (type == TYPE_LDST)
877 do_alignment_finish_ldst(addr, instr, regs, offset);
878
879 return 0;
880
881 bad_or_fault:
882 if (type == TYPE_ERROR)
883 goto bad;
884 /*
885 * We got a fault - fix it up, or die.
886 */
887 do_bad_area(addr, fsr, regs);
888 return 0;
889
890 swp:
891 printk(KERN_ERR "Alignment trap: not handling swp instruction\n");
892
893 bad:
894 /*
895 * Oops, we didn't handle the instruction.
896 */
897 printk(KERN_ERR "Alignment trap: not handling instruction "
898 "%0*lx at [<%08lx>]\n",
899 isize << 1,
900 isize == 2 ? tinstr : instr, instrptr);
901 ai_skipped += 1;
902 return 1;
903
904 user:
905 ai_user += 1;
906
907 if (ai_usermode & UM_WARN)
908 printk("Alignment trap: %s (%d) PC=0x%08lx Instr=0x%0*lx "
909 "Address=0x%08lx FSR 0x%03x\n", current->comm,
910 task_pid_nr(current), instrptr,
911 isize << 1,
912 isize == 2 ? tinstr : instr,
913 addr, fsr);
914
915 if (ai_usermode & UM_FIXUP)
916 goto fixup;
917
918 if (ai_usermode & UM_SIGNAL) {
919 siginfo_t si;
920
921 si.si_signo = SIGBUS;
922 si.si_errno = 0;
923 si.si_code = BUS_ADRALN;
924 si.si_addr = (void __user *)addr;
925
926 force_sig_info(si.si_signo, &si, current);
927 } else {
928 /*
929 * We're about to disable the alignment trap and return to
930 * user space. But if an interrupt occurs before actually
931 * reaching user space, then the IRQ vector entry code will
932 * notice that we were still in kernel space and therefore
933 * the alignment trap won't be re-enabled in that case as it
934 * is presumed to be always on from kernel space.
935 * Let's prevent that race by disabling interrupts here (they
936 * are disabled on the way back to user space anyway in
937 * entry-common.S) and disable the alignment trap only if
938 * there is no work pending for this thread.
939 */
940 raw_local_irq_disable();
941 if (!(current_thread_info()->flags & _TIF_WORK_MASK))
942 set_cr(cr_no_alignment);
943 }
944
945 return 0;
946}
947
948/*
949 * This needs to be done after sysctl_init, otherwise sys/ will be
950 * overwritten. Actually, this shouldn't be in sys/ at all since
951 * it isn't a sysctl, and it doesn't contain sysctl information.
952 * We now locate it in /proc/cpu/alignment instead.
953 */
954static int __init alignment_init(void)
955{
956#ifdef CONFIG_PROC_FS
957 struct proc_dir_entry *res;
958
959 res = proc_create("cpu/alignment", S_IWUSR | S_IRUGO, NULL,
960 &alignment_proc_fops);
961 if (!res)
962 return -ENOMEM;
963#endif
964
965 if (cpu_is_v6_unaligned()) {
966 cr_alignment &= ~CR_A;
967 cr_no_alignment &= ~CR_A;
968 set_cr(cr_alignment);
969 ai_usermode = safe_usermode(ai_usermode, false);
970 }
971
972 hook_fault_code(FAULT_CODE_ALIGNMENT, do_alignment, SIGBUS, BUS_ADRALN,
973 "alignment exception");
974
975 /*
976 * ARMv6K and ARMv7 use fault status 3 (0b00011) as Access Flag section
977 * fault, not as alignment error.
978 *
979 * TODO: handle ARMv6K properly. Runtime check for 'K' extension is
980 * needed.
981 */
982 if (cpu_architecture() <= CPU_ARCH_ARMv6) {
983 hook_fault_code(3, do_alignment, SIGBUS, BUS_ADRALN,
984 "alignment exception");
985 }
986
987 return 0;
988}
989
990fs_initcall(alignment_init);
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * linux/arch/arm/mm/alignment.c
4 *
5 * Copyright (C) 1995 Linus Torvalds
6 * Modifications for ARM processor (c) 1995-2001 Russell King
7 * Thumb alignment fault fixups (c) 2004 MontaVista Software, Inc.
8 * - Adapted from gdb/sim/arm/thumbemu.c -- Thumb instruction emulation.
9 * Copyright (C) 1996, Cygnus Software Technologies Ltd.
10 */
11#include <linux/moduleparam.h>
12#include <linux/compiler.h>
13#include <linux/kernel.h>
14#include <linux/sched/debug.h>
15#include <linux/errno.h>
16#include <linux/string.h>
17#include <linux/proc_fs.h>
18#include <linux/seq_file.h>
19#include <linux/init.h>
20#include <linux/sched/signal.h>
21#include <linux/uaccess.h>
22
23#include <asm/cp15.h>
24#include <asm/system_info.h>
25#include <asm/unaligned.h>
26#include <asm/opcodes.h>
27
28#include "fault.h"
29#include "mm.h"
30
31/*
32 * 32-bit misaligned trap handler (c) 1998 San Mehat (CCC) -July 1998
33 * /proc/sys/debug/alignment, modified and integrated into
34 * Linux 2.1 by Russell King
35 *
36 * Speed optimisations and better fault handling by Russell King.
37 *
38 * *** NOTE ***
39 * This code is not portable to processors with late data abort handling.
40 */
41#define CODING_BITS(i) (i & 0x0e000000)
42#define COND_BITS(i) (i & 0xf0000000)
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
76static unsigned long ai_user;
77static unsigned long ai_sys;
78static void *ai_sys_last_pc;
79static unsigned long ai_skipped;
80static unsigned long ai_half;
81static unsigned long ai_word;
82static unsigned long ai_dword;
83static unsigned long ai_multi;
84static int ai_usermode;
85static unsigned long cr_no_alignment;
86
87core_param(alignment, ai_usermode, int, 0600);
88
89#define UM_WARN (1 << 0)
90#define UM_FIXUP (1 << 1)
91#define UM_SIGNAL (1 << 2)
92
93/* Return true if and only if the ARMv6 unaligned access model is in use. */
94static bool cpu_is_v6_unaligned(void)
95{
96 return cpu_architecture() >= CPU_ARCH_ARMv6 && get_cr() & CR_U;
97}
98
99static int safe_usermode(int new_usermode, bool warn)
100{
101 /*
102 * ARMv6 and later CPUs can perform unaligned accesses for
103 * most single load and store instructions up to word size.
104 * LDM, STM, LDRD and STRD still need to be handled.
105 *
106 * Ignoring the alignment fault is not an option on these
107 * CPUs since we spin re-faulting the instruction without
108 * making any progress.
109 */
110 if (cpu_is_v6_unaligned() && !(new_usermode & (UM_FIXUP | UM_SIGNAL))) {
111 new_usermode |= UM_FIXUP;
112
113 if (warn)
114 pr_warn("alignment: ignoring faults is unsafe on this CPU. Defaulting to fixup mode.\n");
115 }
116
117 return new_usermode;
118}
119
120#ifdef CONFIG_PROC_FS
121static const char *usermode_action[] = {
122 "ignored",
123 "warn",
124 "fixup",
125 "fixup+warn",
126 "signal",
127 "signal+warn"
128};
129
130static int alignment_proc_show(struct seq_file *m, void *v)
131{
132 seq_printf(m, "User:\t\t%lu\n", ai_user);
133 seq_printf(m, "System:\t\t%lu (%pS)\n", ai_sys, ai_sys_last_pc);
134 seq_printf(m, "Skipped:\t%lu\n", ai_skipped);
135 seq_printf(m, "Half:\t\t%lu\n", ai_half);
136 seq_printf(m, "Word:\t\t%lu\n", ai_word);
137 if (cpu_architecture() >= CPU_ARCH_ARMv5TE)
138 seq_printf(m, "DWord:\t\t%lu\n", ai_dword);
139 seq_printf(m, "Multi:\t\t%lu\n", ai_multi);
140 seq_printf(m, "User faults:\t%i (%s)\n", ai_usermode,
141 usermode_action[ai_usermode]);
142
143 return 0;
144}
145
146static int alignment_proc_open(struct inode *inode, struct file *file)
147{
148 return single_open(file, alignment_proc_show, NULL);
149}
150
151static ssize_t alignment_proc_write(struct file *file, const char __user *buffer,
152 size_t count, loff_t *pos)
153{
154 char mode;
155
156 if (count > 0) {
157 if (get_user(mode, buffer))
158 return -EFAULT;
159 if (mode >= '0' && mode <= '5')
160 ai_usermode = safe_usermode(mode - '0', true);
161 }
162 return count;
163}
164
165static const struct file_operations alignment_proc_fops = {
166 .open = alignment_proc_open,
167 .read = seq_read,
168 .llseek = seq_lseek,
169 .release = single_release,
170 .write = alignment_proc_write,
171};
172#endif /* CONFIG_PROC_FS */
173
174union offset_union {
175 unsigned long un;
176 signed long sn;
177};
178
179#define TYPE_ERROR 0
180#define TYPE_FAULT 1
181#define TYPE_LDST 2
182#define TYPE_DONE 3
183
184#ifdef __ARMEB__
185#define BE 1
186#define FIRST_BYTE_16 "mov %1, %1, ror #8\n"
187#define FIRST_BYTE_32 "mov %1, %1, ror #24\n"
188#define NEXT_BYTE "ror #24"
189#else
190#define BE 0
191#define FIRST_BYTE_16
192#define FIRST_BYTE_32
193#define NEXT_BYTE "lsr #8"
194#endif
195
196#define __get8_unaligned_check(ins,val,addr,err) \
197 __asm__( \
198 ARM( "1: "ins" %1, [%2], #1\n" ) \
199 THUMB( "1: "ins" %1, [%2]\n" ) \
200 THUMB( " add %2, %2, #1\n" ) \
201 "2:\n" \
202 " .pushsection .text.fixup,\"ax\"\n" \
203 " .align 2\n" \
204 "3: mov %0, #1\n" \
205 " b 2b\n" \
206 " .popsection\n" \
207 " .pushsection __ex_table,\"a\"\n" \
208 " .align 3\n" \
209 " .long 1b, 3b\n" \
210 " .popsection\n" \
211 : "=r" (err), "=&r" (val), "=r" (addr) \
212 : "0" (err), "2" (addr))
213
214#define __get16_unaligned_check(ins,val,addr) \
215 do { \
216 unsigned int err = 0, v, a = addr; \
217 __get8_unaligned_check(ins,v,a,err); \
218 val = v << ((BE) ? 8 : 0); \
219 __get8_unaligned_check(ins,v,a,err); \
220 val |= v << ((BE) ? 0 : 8); \
221 if (err) \
222 goto fault; \
223 } while (0)
224
225#define get16_unaligned_check(val,addr) \
226 __get16_unaligned_check("ldrb",val,addr)
227
228#define get16t_unaligned_check(val,addr) \
229 __get16_unaligned_check("ldrbt",val,addr)
230
231#define __get32_unaligned_check(ins,val,addr) \
232 do { \
233 unsigned int err = 0, v, a = addr; \
234 __get8_unaligned_check(ins,v,a,err); \
235 val = v << ((BE) ? 24 : 0); \
236 __get8_unaligned_check(ins,v,a,err); \
237 val |= v << ((BE) ? 16 : 8); \
238 __get8_unaligned_check(ins,v,a,err); \
239 val |= v << ((BE) ? 8 : 16); \
240 __get8_unaligned_check(ins,v,a,err); \
241 val |= v << ((BE) ? 0 : 24); \
242 if (err) \
243 goto fault; \
244 } while (0)
245
246#define get32_unaligned_check(val,addr) \
247 __get32_unaligned_check("ldrb",val,addr)
248
249#define get32t_unaligned_check(val,addr) \
250 __get32_unaligned_check("ldrbt",val,addr)
251
252#define __put16_unaligned_check(ins,val,addr) \
253 do { \
254 unsigned int err = 0, v = val, a = addr; \
255 __asm__( FIRST_BYTE_16 \
256 ARM( "1: "ins" %1, [%2], #1\n" ) \
257 THUMB( "1: "ins" %1, [%2]\n" ) \
258 THUMB( " add %2, %2, #1\n" ) \
259 " mov %1, %1, "NEXT_BYTE"\n" \
260 "2: "ins" %1, [%2]\n" \
261 "3:\n" \
262 " .pushsection .text.fixup,\"ax\"\n" \
263 " .align 2\n" \
264 "4: mov %0, #1\n" \
265 " b 3b\n" \
266 " .popsection\n" \
267 " .pushsection __ex_table,\"a\"\n" \
268 " .align 3\n" \
269 " .long 1b, 4b\n" \
270 " .long 2b, 4b\n" \
271 " .popsection\n" \
272 : "=r" (err), "=&r" (v), "=&r" (a) \
273 : "0" (err), "1" (v), "2" (a)); \
274 if (err) \
275 goto fault; \
276 } while (0)
277
278#define put16_unaligned_check(val,addr) \
279 __put16_unaligned_check("strb",val,addr)
280
281#define put16t_unaligned_check(val,addr) \
282 __put16_unaligned_check("strbt",val,addr)
283
284#define __put32_unaligned_check(ins,val,addr) \
285 do { \
286 unsigned int err = 0, v = val, a = addr; \
287 __asm__( FIRST_BYTE_32 \
288 ARM( "1: "ins" %1, [%2], #1\n" ) \
289 THUMB( "1: "ins" %1, [%2]\n" ) \
290 THUMB( " add %2, %2, #1\n" ) \
291 " mov %1, %1, "NEXT_BYTE"\n" \
292 ARM( "2: "ins" %1, [%2], #1\n" ) \
293 THUMB( "2: "ins" %1, [%2]\n" ) \
294 THUMB( " add %2, %2, #1\n" ) \
295 " mov %1, %1, "NEXT_BYTE"\n" \
296 ARM( "3: "ins" %1, [%2], #1\n" ) \
297 THUMB( "3: "ins" %1, [%2]\n" ) \
298 THUMB( " add %2, %2, #1\n" ) \
299 " mov %1, %1, "NEXT_BYTE"\n" \
300 "4: "ins" %1, [%2]\n" \
301 "5:\n" \
302 " .pushsection .text.fixup,\"ax\"\n" \
303 " .align 2\n" \
304 "6: mov %0, #1\n" \
305 " b 5b\n" \
306 " .popsection\n" \
307 " .pushsection __ex_table,\"a\"\n" \
308 " .align 3\n" \
309 " .long 1b, 6b\n" \
310 " .long 2b, 6b\n" \
311 " .long 3b, 6b\n" \
312 " .long 4b, 6b\n" \
313 " .popsection\n" \
314 : "=r" (err), "=&r" (v), "=&r" (a) \
315 : "0" (err), "1" (v), "2" (a)); \
316 if (err) \
317 goto fault; \
318 } while (0)
319
320#define put32_unaligned_check(val,addr) \
321 __put32_unaligned_check("strb", val, addr)
322
323#define put32t_unaligned_check(val,addr) \
324 __put32_unaligned_check("strbt", val, addr)
325
326static void
327do_alignment_finish_ldst(unsigned long addr, u32 instr, struct pt_regs *regs, union offset_union offset)
328{
329 if (!LDST_U_BIT(instr))
330 offset.un = -offset.un;
331
332 if (!LDST_P_BIT(instr))
333 addr += offset.un;
334
335 if (!LDST_P_BIT(instr) || LDST_W_BIT(instr))
336 regs->uregs[RN_BITS(instr)] = addr;
337}
338
339static int
340do_alignment_ldrhstrh(unsigned long addr, u32 instr, struct pt_regs *regs)
341{
342 unsigned int rd = RD_BITS(instr);
343
344 ai_half += 1;
345
346 if (user_mode(regs))
347 goto user;
348
349 if (LDST_L_BIT(instr)) {
350 unsigned long val;
351 get16_unaligned_check(val, addr);
352
353 /* signed half-word? */
354 if (instr & 0x40)
355 val = (signed long)((signed short) val);
356
357 regs->uregs[rd] = val;
358 } else
359 put16_unaligned_check(regs->uregs[rd], addr);
360
361 return TYPE_LDST;
362
363 user:
364 if (LDST_L_BIT(instr)) {
365 unsigned long val;
366 unsigned int __ua_flags = uaccess_save_and_enable();
367
368 get16t_unaligned_check(val, addr);
369 uaccess_restore(__ua_flags);
370
371 /* signed half-word? */
372 if (instr & 0x40)
373 val = (signed long)((signed short) val);
374
375 regs->uregs[rd] = val;
376 } else {
377 unsigned int __ua_flags = uaccess_save_and_enable();
378 put16t_unaligned_check(regs->uregs[rd], addr);
379 uaccess_restore(__ua_flags);
380 }
381
382 return TYPE_LDST;
383
384 fault:
385 return TYPE_FAULT;
386}
387
388static int
389do_alignment_ldrdstrd(unsigned long addr, u32 instr, struct pt_regs *regs)
390{
391 unsigned int rd = RD_BITS(instr);
392 unsigned int rd2;
393 int load;
394
395 if ((instr & 0xfe000000) == 0xe8000000) {
396 /* ARMv7 Thumb-2 32-bit LDRD/STRD */
397 rd2 = (instr >> 8) & 0xf;
398 load = !!(LDST_L_BIT(instr));
399 } else if (((rd & 1) == 1) || (rd == 14))
400 goto bad;
401 else {
402 load = ((instr & 0xf0) == 0xd0);
403 rd2 = rd + 1;
404 }
405
406 ai_dword += 1;
407
408 if (user_mode(regs))
409 goto user;
410
411 if (load) {
412 unsigned long val;
413 get32_unaligned_check(val, addr);
414 regs->uregs[rd] = val;
415 get32_unaligned_check(val, addr + 4);
416 regs->uregs[rd2] = val;
417 } else {
418 put32_unaligned_check(regs->uregs[rd], addr);
419 put32_unaligned_check(regs->uregs[rd2], addr + 4);
420 }
421
422 return TYPE_LDST;
423
424 user:
425 if (load) {
426 unsigned long val, val2;
427 unsigned int __ua_flags = uaccess_save_and_enable();
428
429 get32t_unaligned_check(val, addr);
430 get32t_unaligned_check(val2, addr + 4);
431
432 uaccess_restore(__ua_flags);
433
434 regs->uregs[rd] = val;
435 regs->uregs[rd2] = val2;
436 } else {
437 unsigned int __ua_flags = uaccess_save_and_enable();
438 put32t_unaligned_check(regs->uregs[rd], addr);
439 put32t_unaligned_check(regs->uregs[rd2], addr + 4);
440 uaccess_restore(__ua_flags);
441 }
442
443 return TYPE_LDST;
444 bad:
445 return TYPE_ERROR;
446 fault:
447 return TYPE_FAULT;
448}
449
450static int
451do_alignment_ldrstr(unsigned long addr, u32 instr, struct pt_regs *regs)
452{
453 unsigned int rd = RD_BITS(instr);
454
455 ai_word += 1;
456
457 if ((!LDST_P_BIT(instr) && LDST_W_BIT(instr)) || user_mode(regs))
458 goto trans;
459
460 if (LDST_L_BIT(instr)) {
461 unsigned int val;
462 get32_unaligned_check(val, addr);
463 regs->uregs[rd] = val;
464 } else
465 put32_unaligned_check(regs->uregs[rd], addr);
466 return TYPE_LDST;
467
468 trans:
469 if (LDST_L_BIT(instr)) {
470 unsigned int val;
471 unsigned int __ua_flags = uaccess_save_and_enable();
472 get32t_unaligned_check(val, addr);
473 uaccess_restore(__ua_flags);
474 regs->uregs[rd] = val;
475 } else {
476 unsigned int __ua_flags = uaccess_save_and_enable();
477 put32t_unaligned_check(regs->uregs[rd], addr);
478 uaccess_restore(__ua_flags);
479 }
480 return TYPE_LDST;
481
482 fault:
483 return TYPE_FAULT;
484}
485
486/*
487 * LDM/STM alignment handler.
488 *
489 * There are 4 variants of this instruction:
490 *
491 * B = rn pointer before instruction, A = rn pointer after instruction
492 * ------ increasing address ----->
493 * | | r0 | r1 | ... | rx | |
494 * PU = 01 B A
495 * PU = 11 B A
496 * PU = 00 A B
497 * PU = 10 A B
498 */
499static int
500do_alignment_ldmstm(unsigned long addr, u32 instr, struct pt_regs *regs)
501{
502 unsigned int rd, rn, correction, nr_regs, regbits;
503 unsigned long eaddr, newaddr;
504
505 if (LDM_S_BIT(instr))
506 goto bad;
507
508 correction = 4; /* processor implementation defined */
509 regs->ARM_pc += correction;
510
511 ai_multi += 1;
512
513 /* count the number of registers in the mask to be transferred */
514 nr_regs = hweight16(REGMASK_BITS(instr)) * 4;
515
516 rn = RN_BITS(instr);
517 newaddr = eaddr = regs->uregs[rn];
518
519 if (!LDST_U_BIT(instr))
520 nr_regs = -nr_regs;
521 newaddr += nr_regs;
522 if (!LDST_U_BIT(instr))
523 eaddr = newaddr;
524
525 if (LDST_P_EQ_U(instr)) /* U = P */
526 eaddr += 4;
527
528 /*
529 * For alignment faults on the ARM922T/ARM920T the MMU makes
530 * the FSR (and hence addr) equal to the updated base address
531 * of the multiple access rather than the restored value.
532 * Switch this message off if we've got a ARM92[02], otherwise
533 * [ls]dm alignment faults are noisy!
534 */
535#if !(defined CONFIG_CPU_ARM922T) && !(defined CONFIG_CPU_ARM920T)
536 /*
537 * This is a "hint" - we already have eaddr worked out by the
538 * processor for us.
539 */
540 if (addr != eaddr) {
541 pr_err("LDMSTM: PC = %08lx, instr = %08x, "
542 "addr = %08lx, eaddr = %08lx\n",
543 instruction_pointer(regs), instr, addr, eaddr);
544 show_regs(regs);
545 }
546#endif
547
548 if (user_mode(regs)) {
549 unsigned int __ua_flags = uaccess_save_and_enable();
550 for (regbits = REGMASK_BITS(instr), rd = 0; regbits;
551 regbits >>= 1, rd += 1)
552 if (regbits & 1) {
553 if (LDST_L_BIT(instr)) {
554 unsigned int val;
555 get32t_unaligned_check(val, eaddr);
556 regs->uregs[rd] = val;
557 } else
558 put32t_unaligned_check(regs->uregs[rd], eaddr);
559 eaddr += 4;
560 }
561 uaccess_restore(__ua_flags);
562 } else {
563 for (regbits = REGMASK_BITS(instr), rd = 0; regbits;
564 regbits >>= 1, rd += 1)
565 if (regbits & 1) {
566 if (LDST_L_BIT(instr)) {
567 unsigned int val;
568 get32_unaligned_check(val, eaddr);
569 regs->uregs[rd] = val;
570 } else
571 put32_unaligned_check(regs->uregs[rd], eaddr);
572 eaddr += 4;
573 }
574 }
575
576 if (LDST_W_BIT(instr))
577 regs->uregs[rn] = newaddr;
578 if (!LDST_L_BIT(instr) || !(REGMASK_BITS(instr) & (1 << 15)))
579 regs->ARM_pc -= correction;
580 return TYPE_DONE;
581
582fault:
583 regs->ARM_pc -= correction;
584 return TYPE_FAULT;
585
586bad:
587 pr_err("Alignment trap: not handling ldm with s-bit set\n");
588 return TYPE_ERROR;
589}
590
591/*
592 * Convert Thumb ld/st instruction forms to equivalent ARM instructions so
593 * we can reuse ARM userland alignment fault fixups for Thumb.
594 *
595 * This implementation was initially based on the algorithm found in
596 * gdb/sim/arm/thumbemu.c. It is basically just a code reduction of same
597 * to convert only Thumb ld/st instruction forms to equivalent ARM forms.
598 *
599 * NOTES:
600 * 1. Comments below refer to ARM ARM DDI0100E Thumb Instruction sections.
601 * 2. If for some reason we're passed an non-ld/st Thumb instruction to
602 * decode, we return 0xdeadc0de. This should never happen under normal
603 * circumstances but if it does, we've got other problems to deal with
604 * elsewhere and we obviously can't fix those problems here.
605 */
606
607static unsigned long
608thumb2arm(u16 tinstr)
609{
610 u32 L = (tinstr & (1<<11)) >> 11;
611
612 switch ((tinstr & 0xf800) >> 11) {
613 /* 6.5.1 Format 1: */
614 case 0x6000 >> 11: /* 7.1.52 STR(1) */
615 case 0x6800 >> 11: /* 7.1.26 LDR(1) */
616 case 0x7000 >> 11: /* 7.1.55 STRB(1) */
617 case 0x7800 >> 11: /* 7.1.30 LDRB(1) */
618 return 0xe5800000 |
619 ((tinstr & (1<<12)) << (22-12)) | /* fixup */
620 (L<<20) | /* L==1? */
621 ((tinstr & (7<<0)) << (12-0)) | /* Rd */
622 ((tinstr & (7<<3)) << (16-3)) | /* Rn */
623 ((tinstr & (31<<6)) >> /* immed_5 */
624 (6 - ((tinstr & (1<<12)) ? 0 : 2)));
625 case 0x8000 >> 11: /* 7.1.57 STRH(1) */
626 case 0x8800 >> 11: /* 7.1.32 LDRH(1) */
627 return 0xe1c000b0 |
628 (L<<20) | /* L==1? */
629 ((tinstr & (7<<0)) << (12-0)) | /* Rd */
630 ((tinstr & (7<<3)) << (16-3)) | /* Rn */
631 ((tinstr & (7<<6)) >> (6-1)) | /* immed_5[2:0] */
632 ((tinstr & (3<<9)) >> (9-8)); /* immed_5[4:3] */
633
634 /* 6.5.1 Format 2: */
635 case 0x5000 >> 11:
636 case 0x5800 >> 11:
637 {
638 static const u32 subset[8] = {
639 0xe7800000, /* 7.1.53 STR(2) */
640 0xe18000b0, /* 7.1.58 STRH(2) */
641 0xe7c00000, /* 7.1.56 STRB(2) */
642 0xe19000d0, /* 7.1.34 LDRSB */
643 0xe7900000, /* 7.1.27 LDR(2) */
644 0xe19000b0, /* 7.1.33 LDRH(2) */
645 0xe7d00000, /* 7.1.31 LDRB(2) */
646 0xe19000f0 /* 7.1.35 LDRSH */
647 };
648 return subset[(tinstr & (7<<9)) >> 9] |
649 ((tinstr & (7<<0)) << (12-0)) | /* Rd */
650 ((tinstr & (7<<3)) << (16-3)) | /* Rn */
651 ((tinstr & (7<<6)) >> (6-0)); /* Rm */
652 }
653
654 /* 6.5.1 Format 3: */
655 case 0x4800 >> 11: /* 7.1.28 LDR(3) */
656 /* NOTE: This case is not technically possible. We're
657 * loading 32-bit memory data via PC relative
658 * addressing mode. So we can and should eliminate
659 * this case. But I'll leave it here for now.
660 */
661 return 0xe59f0000 |
662 ((tinstr & (7<<8)) << (12-8)) | /* Rd */
663 ((tinstr & 255) << (2-0)); /* immed_8 */
664
665 /* 6.5.1 Format 4: */
666 case 0x9000 >> 11: /* 7.1.54 STR(3) */
667 case 0x9800 >> 11: /* 7.1.29 LDR(4) */
668 return 0xe58d0000 |
669 (L<<20) | /* L==1? */
670 ((tinstr & (7<<8)) << (12-8)) | /* Rd */
671 ((tinstr & 255) << 2); /* immed_8 */
672
673 /* 6.6.1 Format 1: */
674 case 0xc000 >> 11: /* 7.1.51 STMIA */
675 case 0xc800 >> 11: /* 7.1.25 LDMIA */
676 {
677 u32 Rn = (tinstr & (7<<8)) >> 8;
678 u32 W = ((L<<Rn) & (tinstr&255)) ? 0 : 1<<21;
679
680 return 0xe8800000 | W | (L<<20) | (Rn<<16) |
681 (tinstr&255);
682 }
683
684 /* 6.6.1 Format 2: */
685 case 0xb000 >> 11: /* 7.1.48 PUSH */
686 case 0xb800 >> 11: /* 7.1.47 POP */
687 if ((tinstr & (3 << 9)) == 0x0400) {
688 static const u32 subset[4] = {
689 0xe92d0000, /* STMDB sp!,{registers} */
690 0xe92d4000, /* STMDB sp!,{registers,lr} */
691 0xe8bd0000, /* LDMIA sp!,{registers} */
692 0xe8bd8000 /* LDMIA sp!,{registers,pc} */
693 };
694 return subset[(L<<1) | ((tinstr & (1<<8)) >> 8)] |
695 (tinstr & 255); /* register_list */
696 }
697 /* Else, fall through - for illegal instruction case */
698
699 default:
700 return BAD_INSTR;
701 }
702}
703
704/*
705 * Convert Thumb-2 32 bit LDM, STM, LDRD, STRD to equivalent instruction
706 * handlable by ARM alignment handler, also find the corresponding handler,
707 * so that we can reuse ARM userland alignment fault fixups for Thumb.
708 *
709 * @pinstr: original Thumb-2 instruction; returns new handlable instruction
710 * @regs: register context.
711 * @poffset: return offset from faulted addr for later writeback
712 *
713 * NOTES:
714 * 1. Comments below refer to ARMv7 DDI0406A Thumb Instruction sections.
715 * 2. Register name Rt from ARMv7 is same as Rd from ARMv6 (Rd is Rt)
716 */
717static void *
718do_alignment_t32_to_handler(u32 *pinstr, struct pt_regs *regs,
719 union offset_union *poffset)
720{
721 u32 instr = *pinstr;
722 u16 tinst1 = (instr >> 16) & 0xffff;
723 u16 tinst2 = instr & 0xffff;
724
725 switch (tinst1 & 0xffe0) {
726 /* A6.3.5 Load/Store multiple */
727 case 0xe880: /* STM/STMIA/STMEA,LDM/LDMIA, PUSH/POP T2 */
728 case 0xe8a0: /* ...above writeback version */
729 case 0xe900: /* STMDB/STMFD, LDMDB/LDMEA */
730 case 0xe920: /* ...above writeback version */
731 /* no need offset decision since handler calculates it */
732 return do_alignment_ldmstm;
733
734 case 0xf840: /* POP/PUSH T3 (single register) */
735 if (RN_BITS(instr) == 13 && (tinst2 & 0x09ff) == 0x0904) {
736 u32 L = !!(LDST_L_BIT(instr));
737 const u32 subset[2] = {
738 0xe92d0000, /* STMDB sp!,{registers} */
739 0xe8bd0000, /* LDMIA sp!,{registers} */
740 };
741 *pinstr = subset[L] | (1<<RD_BITS(instr));
742 return do_alignment_ldmstm;
743 }
744 /* Else fall through for illegal instruction case */
745 break;
746
747 /* A6.3.6 Load/store double, STRD/LDRD(immed, lit, reg) */
748 case 0xe860:
749 case 0xe960:
750 case 0xe8e0:
751 case 0xe9e0:
752 poffset->un = (tinst2 & 0xff) << 2;
753 /* Fall through */
754
755 case 0xe940:
756 case 0xe9c0:
757 return do_alignment_ldrdstrd;
758
759 /*
760 * No need to handle load/store instructions up to word size
761 * since ARMv6 and later CPUs can perform unaligned accesses.
762 */
763 default:
764 break;
765 }
766 return NULL;
767}
768
769static int alignment_get_arm(struct pt_regs *regs, u32 *ip, u32 *inst)
770{
771 u32 instr = 0;
772 int fault;
773
774 if (user_mode(regs))
775 fault = get_user(instr, ip);
776 else
777 fault = probe_kernel_address(ip, instr);
778
779 *inst = __mem_to_opcode_arm(instr);
780
781 return fault;
782}
783
784static int alignment_get_thumb(struct pt_regs *regs, u16 *ip, u16 *inst)
785{
786 u16 instr = 0;
787 int fault;
788
789 if (user_mode(regs))
790 fault = get_user(instr, ip);
791 else
792 fault = probe_kernel_address(ip, instr);
793
794 *inst = __mem_to_opcode_thumb16(instr);
795
796 return fault;
797}
798
799static int
800do_alignment(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
801{
802 union offset_union uninitialized_var(offset);
803 unsigned long instrptr;
804 int (*handler)(unsigned long addr, u32 instr, struct pt_regs *regs);
805 unsigned int type;
806 u32 instr = 0;
807 u16 tinstr = 0;
808 int isize = 4;
809 int thumb2_32b = 0;
810 int fault;
811
812 if (interrupts_enabled(regs))
813 local_irq_enable();
814
815 instrptr = instruction_pointer(regs);
816
817 if (thumb_mode(regs)) {
818 u16 *ptr = (u16 *)(instrptr & ~1);
819
820 fault = alignment_get_thumb(regs, ptr, &tinstr);
821 if (!fault) {
822 if (cpu_architecture() >= CPU_ARCH_ARMv7 &&
823 IS_T32(tinstr)) {
824 /* Thumb-2 32-bit */
825 u16 tinst2;
826 fault = alignment_get_thumb(regs, ptr + 1, &tinst2);
827 instr = __opcode_thumb32_compose(tinstr, tinst2);
828 thumb2_32b = 1;
829 } else {
830 isize = 2;
831 instr = thumb2arm(tinstr);
832 }
833 }
834 } else {
835 fault = alignment_get_arm(regs, (void *)instrptr, &instr);
836 }
837
838 if (fault) {
839 type = TYPE_FAULT;
840 goto bad_or_fault;
841 }
842
843 if (user_mode(regs))
844 goto user;
845
846 ai_sys += 1;
847 ai_sys_last_pc = (void *)instruction_pointer(regs);
848
849 fixup:
850
851 regs->ARM_pc += isize;
852
853 switch (CODING_BITS(instr)) {
854 case 0x00000000: /* 3.13.4 load/store instruction extensions */
855 if (LDSTHD_I_BIT(instr))
856 offset.un = (instr & 0xf00) >> 4 | (instr & 15);
857 else
858 offset.un = regs->uregs[RM_BITS(instr)];
859
860 if ((instr & 0x000000f0) == 0x000000b0 || /* LDRH, STRH */
861 (instr & 0x001000f0) == 0x001000f0) /* LDRSH */
862 handler = do_alignment_ldrhstrh;
863 else if ((instr & 0x001000f0) == 0x000000d0 || /* LDRD */
864 (instr & 0x001000f0) == 0x000000f0) /* STRD */
865 handler = do_alignment_ldrdstrd;
866 else if ((instr & 0x01f00ff0) == 0x01000090) /* SWP */
867 goto swp;
868 else
869 goto bad;
870 break;
871
872 case 0x04000000: /* ldr or str immediate */
873 if (COND_BITS(instr) == 0xf0000000) /* NEON VLDn, VSTn */
874 goto bad;
875 offset.un = OFFSET_BITS(instr);
876 handler = do_alignment_ldrstr;
877 break;
878
879 case 0x06000000: /* ldr or str register */
880 offset.un = regs->uregs[RM_BITS(instr)];
881
882 if (IS_SHIFT(instr)) {
883 unsigned int shiftval = SHIFT_BITS(instr);
884
885 switch(SHIFT_TYPE(instr)) {
886 case SHIFT_LSL:
887 offset.un <<= shiftval;
888 break;
889
890 case SHIFT_LSR:
891 offset.un >>= shiftval;
892 break;
893
894 case SHIFT_ASR:
895 offset.sn >>= shiftval;
896 break;
897
898 case SHIFT_RORRRX:
899 if (shiftval == 0) {
900 offset.un >>= 1;
901 if (regs->ARM_cpsr & PSR_C_BIT)
902 offset.un |= 1 << 31;
903 } else
904 offset.un = offset.un >> shiftval |
905 offset.un << (32 - shiftval);
906 break;
907 }
908 }
909 handler = do_alignment_ldrstr;
910 break;
911
912 case 0x08000000: /* ldm or stm, or thumb-2 32bit instruction */
913 if (thumb2_32b) {
914 offset.un = 0;
915 handler = do_alignment_t32_to_handler(&instr, regs, &offset);
916 } else {
917 offset.un = 0;
918 handler = do_alignment_ldmstm;
919 }
920 break;
921
922 default:
923 goto bad;
924 }
925
926 if (!handler)
927 goto bad;
928 type = handler(addr, instr, regs);
929
930 if (type == TYPE_ERROR || type == TYPE_FAULT) {
931 regs->ARM_pc -= isize;
932 goto bad_or_fault;
933 }
934
935 if (type == TYPE_LDST)
936 do_alignment_finish_ldst(addr, instr, regs, offset);
937
938 return 0;
939
940 bad_or_fault:
941 if (type == TYPE_ERROR)
942 goto bad;
943 /*
944 * We got a fault - fix it up, or die.
945 */
946 do_bad_area(addr, fsr, regs);
947 return 0;
948
949 swp:
950 pr_err("Alignment trap: not handling swp instruction\n");
951
952 bad:
953 /*
954 * Oops, we didn't handle the instruction.
955 */
956 pr_err("Alignment trap: not handling instruction "
957 "%0*x at [<%08lx>]\n",
958 isize << 1,
959 isize == 2 ? tinstr : instr, instrptr);
960 ai_skipped += 1;
961 return 1;
962
963 user:
964 ai_user += 1;
965
966 if (ai_usermode & UM_WARN)
967 printk("Alignment trap: %s (%d) PC=0x%08lx Instr=0x%0*x "
968 "Address=0x%08lx FSR 0x%03x\n", current->comm,
969 task_pid_nr(current), instrptr,
970 isize << 1,
971 isize == 2 ? tinstr : instr,
972 addr, fsr);
973
974 if (ai_usermode & UM_FIXUP)
975 goto fixup;
976
977 if (ai_usermode & UM_SIGNAL) {
978 force_sig_fault(SIGBUS, BUS_ADRALN, (void __user *)addr);
979 } else {
980 /*
981 * We're about to disable the alignment trap and return to
982 * user space. But if an interrupt occurs before actually
983 * reaching user space, then the IRQ vector entry code will
984 * notice that we were still in kernel space and therefore
985 * the alignment trap won't be re-enabled in that case as it
986 * is presumed to be always on from kernel space.
987 * Let's prevent that race by disabling interrupts here (they
988 * are disabled on the way back to user space anyway in
989 * entry-common.S) and disable the alignment trap only if
990 * there is no work pending for this thread.
991 */
992 raw_local_irq_disable();
993 if (!(current_thread_info()->flags & _TIF_WORK_MASK))
994 set_cr(cr_no_alignment);
995 }
996
997 return 0;
998}
999
1000static int __init noalign_setup(char *__unused)
1001{
1002 set_cr(__clear_cr(CR_A));
1003 return 1;
1004}
1005__setup("noalign", noalign_setup);
1006
1007/*
1008 * This needs to be done after sysctl_init, otherwise sys/ will be
1009 * overwritten. Actually, this shouldn't be in sys/ at all since
1010 * it isn't a sysctl, and it doesn't contain sysctl information.
1011 * We now locate it in /proc/cpu/alignment instead.
1012 */
1013static int __init alignment_init(void)
1014{
1015#ifdef CONFIG_PROC_FS
1016 struct proc_dir_entry *res;
1017
1018 res = proc_create("cpu/alignment", S_IWUSR | S_IRUGO, NULL,
1019 &alignment_proc_fops);
1020 if (!res)
1021 return -ENOMEM;
1022#endif
1023
1024 if (cpu_is_v6_unaligned()) {
1025 set_cr(__clear_cr(CR_A));
1026 ai_usermode = safe_usermode(ai_usermode, false);
1027 }
1028
1029 cr_no_alignment = get_cr() & ~CR_A;
1030
1031 hook_fault_code(FAULT_CODE_ALIGNMENT, do_alignment, SIGBUS, BUS_ADRALN,
1032 "alignment exception");
1033
1034 /*
1035 * ARMv6K and ARMv7 use fault status 3 (0b00011) as Access Flag section
1036 * fault, not as alignment error.
1037 *
1038 * TODO: handle ARMv6K properly. Runtime check for 'K' extension is
1039 * needed.
1040 */
1041 if (cpu_architecture() <= CPU_ARCH_ARMv6) {
1042 hook_fault_code(3, do_alignment, SIGBUS, BUS_ADRALN,
1043 "alignment exception");
1044 }
1045
1046 return 0;
1047}
1048
1049fs_initcall(alignment_init);