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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/system.h>
26#include <asm/unaligned.h>
27
28#include "fault.h"
29
30/*
31 * 32-bit misaligned trap handler (c) 1998 San Mehat (CCC) -July 1998
32 * /proc/sys/debug/alignment, modified and integrated into
33 * Linux 2.1 by Russell King
34 *
35 * Speed optimisations and better fault handling by Russell King.
36 *
37 * *** NOTE ***
38 * This code is not portable to processors with late data abort handling.
39 */
40#define CODING_BITS(i) (i & 0x0e000000)
41
42#define LDST_I_BIT(i) (i & (1 << 26)) /* Immediate constant */
43#define LDST_P_BIT(i) (i & (1 << 24)) /* Preindex */
44#define LDST_U_BIT(i) (i & (1 << 23)) /* Add offset */
45#define LDST_W_BIT(i) (i & (1 << 21)) /* Writeback */
46#define LDST_L_BIT(i) (i & (1 << 20)) /* Load */
47
48#define LDST_P_EQ_U(i) ((((i) ^ ((i) >> 1)) & (1 << 23)) == 0)
49
50#define LDSTHD_I_BIT(i) (i & (1 << 22)) /* double/half-word immed */
51#define LDM_S_BIT(i) (i & (1 << 22)) /* write CPSR from SPSR */
52
53#define RN_BITS(i) ((i >> 16) & 15) /* Rn */
54#define RD_BITS(i) ((i >> 12) & 15) /* Rd */
55#define RM_BITS(i) (i & 15) /* Rm */
56
57#define REGMASK_BITS(i) (i & 0xffff)
58#define OFFSET_BITS(i) (i & 0x0fff)
59
60#define IS_SHIFT(i) (i & 0x0ff0)
61#define SHIFT_BITS(i) ((i >> 7) & 0x1f)
62#define SHIFT_TYPE(i) (i & 0x60)
63#define SHIFT_LSL 0x00
64#define SHIFT_LSR 0x20
65#define SHIFT_ASR 0x40
66#define SHIFT_RORRRX 0x60
67
68#define BAD_INSTR 0xdeadc0de
69
70/* Thumb-2 32 bit format per ARMv7 DDI0406A A6.3, either f800h,e800h,f800h */
71#define IS_T32(hi16) \
72 (((hi16) & 0xe000) == 0xe000 && ((hi16) & 0x1800))
73
74static unsigned long ai_user;
75static unsigned long ai_sys;
76static unsigned long ai_skipped;
77static unsigned long ai_half;
78static unsigned long ai_word;
79static unsigned long ai_dword;
80static unsigned long ai_multi;
81static int ai_usermode;
82
83core_param(alignment, ai_usermode, int, 0600);
84
85#define UM_WARN (1 << 0)
86#define UM_FIXUP (1 << 1)
87#define UM_SIGNAL (1 << 2)
88
89#ifdef CONFIG_PROC_FS
90static const char *usermode_action[] = {
91 "ignored",
92 "warn",
93 "fixup",
94 "fixup+warn",
95 "signal",
96 "signal+warn"
97};
98
99/* Return true if and only if the ARMv6 unaligned access model is in use. */
100static bool cpu_is_v6_unaligned(void)
101{
102 return cpu_architecture() >= CPU_ARCH_ARMv6 && (cr_alignment & CR_U);
103}
104
105static int safe_usermode(int new_usermode, bool warn)
106{
107 /*
108 * ARMv6 and later CPUs can perform unaligned accesses for
109 * most single load and store instructions up to word size.
110 * LDM, STM, LDRD and STRD still need to be handled.
111 *
112 * Ignoring the alignment fault is not an option on these
113 * CPUs since we spin re-faulting the instruction without
114 * making any progress.
115 */
116 if (cpu_is_v6_unaligned() && !(new_usermode & (UM_FIXUP | UM_SIGNAL))) {
117 new_usermode |= UM_FIXUP;
118
119 if (warn)
120 printk(KERN_WARNING "alignment: ignoring faults is unsafe on this CPU. Defaulting to fixup mode.\n");
121 }
122
123 return new_usermode;
124}
125
126static int alignment_proc_show(struct seq_file *m, void *v)
127{
128 seq_printf(m, "User:\t\t%lu\n", ai_user);
129 seq_printf(m, "System:\t\t%lu\n", ai_sys);
130 seq_printf(m, "Skipped:\t%lu\n", ai_skipped);
131 seq_printf(m, "Half:\t\t%lu\n", ai_half);
132 seq_printf(m, "Word:\t\t%lu\n", ai_word);
133 if (cpu_architecture() >= CPU_ARCH_ARMv5TE)
134 seq_printf(m, "DWord:\t\t%lu\n", ai_dword);
135 seq_printf(m, "Multi:\t\t%lu\n", ai_multi);
136 seq_printf(m, "User faults:\t%i (%s)\n", ai_usermode,
137 usermode_action[ai_usermode]);
138
139 return 0;
140}
141
142static int alignment_proc_open(struct inode *inode, struct file *file)
143{
144 return single_open(file, alignment_proc_show, NULL);
145}
146
147static ssize_t alignment_proc_write(struct file *file, const char __user *buffer,
148 size_t count, loff_t *pos)
149{
150 char mode;
151
152 if (count > 0) {
153 if (get_user(mode, buffer))
154 return -EFAULT;
155 if (mode >= '0' && mode <= '5')
156 ai_usermode = safe_usermode(mode - '0', true);
157 }
158 return count;
159}
160
161static const struct file_operations alignment_proc_fops = {
162 .open = alignment_proc_open,
163 .read = seq_read,
164 .llseek = seq_lseek,
165 .release = single_release,
166 .write = alignment_proc_write,
167};
168#endif /* CONFIG_PROC_FS */
169
170union offset_union {
171 unsigned long un;
172 signed long sn;
173};
174
175#define TYPE_ERROR 0
176#define TYPE_FAULT 1
177#define TYPE_LDST 2
178#define TYPE_DONE 3
179
180#ifdef __ARMEB__
181#define BE 1
182#define FIRST_BYTE_16 "mov %1, %1, ror #8\n"
183#define FIRST_BYTE_32 "mov %1, %1, ror #24\n"
184#define NEXT_BYTE "ror #24"
185#else
186#define BE 0
187#define FIRST_BYTE_16
188#define FIRST_BYTE_32
189#define NEXT_BYTE "lsr #8"
190#endif
191
192#define __get8_unaligned_check(ins,val,addr,err) \
193 __asm__( \
194 ARM( "1: "ins" %1, [%2], #1\n" ) \
195 THUMB( "1: "ins" %1, [%2]\n" ) \
196 THUMB( " add %2, %2, #1\n" ) \
197 "2:\n" \
198 " .pushsection .fixup,\"ax\"\n" \
199 " .align 2\n" \
200 "3: mov %0, #1\n" \
201 " b 2b\n" \
202 " .popsection\n" \
203 " .pushsection __ex_table,\"a\"\n" \
204 " .align 3\n" \
205 " .long 1b, 3b\n" \
206 " .popsection\n" \
207 : "=r" (err), "=&r" (val), "=r" (addr) \
208 : "0" (err), "2" (addr))
209
210#define __get16_unaligned_check(ins,val,addr) \
211 do { \
212 unsigned int err = 0, v, a = addr; \
213 __get8_unaligned_check(ins,v,a,err); \
214 val = v << ((BE) ? 8 : 0); \
215 __get8_unaligned_check(ins,v,a,err); \
216 val |= v << ((BE) ? 0 : 8); \
217 if (err) \
218 goto fault; \
219 } while (0)
220
221#define get16_unaligned_check(val,addr) \
222 __get16_unaligned_check("ldrb",val,addr)
223
224#define get16t_unaligned_check(val,addr) \
225 __get16_unaligned_check("ldrbt",val,addr)
226
227#define __get32_unaligned_check(ins,val,addr) \
228 do { \
229 unsigned int err = 0, v, a = addr; \
230 __get8_unaligned_check(ins,v,a,err); \
231 val = v << ((BE) ? 24 : 0); \
232 __get8_unaligned_check(ins,v,a,err); \
233 val |= v << ((BE) ? 16 : 8); \
234 __get8_unaligned_check(ins,v,a,err); \
235 val |= v << ((BE) ? 8 : 16); \
236 __get8_unaligned_check(ins,v,a,err); \
237 val |= v << ((BE) ? 0 : 24); \
238 if (err) \
239 goto fault; \
240 } while (0)
241
242#define get32_unaligned_check(val,addr) \
243 __get32_unaligned_check("ldrb",val,addr)
244
245#define get32t_unaligned_check(val,addr) \
246 __get32_unaligned_check("ldrbt",val,addr)
247
248#define __put16_unaligned_check(ins,val,addr) \
249 do { \
250 unsigned int err = 0, v = val, a = addr; \
251 __asm__( FIRST_BYTE_16 \
252 ARM( "1: "ins" %1, [%2], #1\n" ) \
253 THUMB( "1: "ins" %1, [%2]\n" ) \
254 THUMB( " add %2, %2, #1\n" ) \
255 " mov %1, %1, "NEXT_BYTE"\n" \
256 "2: "ins" %1, [%2]\n" \
257 "3:\n" \
258 " .pushsection .fixup,\"ax\"\n" \
259 " .align 2\n" \
260 "4: mov %0, #1\n" \
261 " b 3b\n" \
262 " .popsection\n" \
263 " .pushsection __ex_table,\"a\"\n" \
264 " .align 3\n" \
265 " .long 1b, 4b\n" \
266 " .long 2b, 4b\n" \
267 " .popsection\n" \
268 : "=r" (err), "=&r" (v), "=&r" (a) \
269 : "0" (err), "1" (v), "2" (a)); \
270 if (err) \
271 goto fault; \
272 } while (0)
273
274#define put16_unaligned_check(val,addr) \
275 __put16_unaligned_check("strb",val,addr)
276
277#define put16t_unaligned_check(val,addr) \
278 __put16_unaligned_check("strbt",val,addr)
279
280#define __put32_unaligned_check(ins,val,addr) \
281 do { \
282 unsigned int err = 0, v = val, a = addr; \
283 __asm__( FIRST_BYTE_32 \
284 ARM( "1: "ins" %1, [%2], #1\n" ) \
285 THUMB( "1: "ins" %1, [%2]\n" ) \
286 THUMB( " add %2, %2, #1\n" ) \
287 " mov %1, %1, "NEXT_BYTE"\n" \
288 ARM( "2: "ins" %1, [%2], #1\n" ) \
289 THUMB( "2: "ins" %1, [%2]\n" ) \
290 THUMB( " add %2, %2, #1\n" ) \
291 " mov %1, %1, "NEXT_BYTE"\n" \
292 ARM( "3: "ins" %1, [%2], #1\n" ) \
293 THUMB( "3: "ins" %1, [%2]\n" ) \
294 THUMB( " add %2, %2, #1\n" ) \
295 " mov %1, %1, "NEXT_BYTE"\n" \
296 "4: "ins" %1, [%2]\n" \
297 "5:\n" \
298 " .pushsection .fixup,\"ax\"\n" \
299 " .align 2\n" \
300 "6: mov %0, #1\n" \
301 " b 5b\n" \
302 " .popsection\n" \
303 " .pushsection __ex_table,\"a\"\n" \
304 " .align 3\n" \
305 " .long 1b, 6b\n" \
306 " .long 2b, 6b\n" \
307 " .long 3b, 6b\n" \
308 " .long 4b, 6b\n" \
309 " .popsection\n" \
310 : "=r" (err), "=&r" (v), "=&r" (a) \
311 : "0" (err), "1" (v), "2" (a)); \
312 if (err) \
313 goto fault; \
314 } while (0)
315
316#define put32_unaligned_check(val,addr) \
317 __put32_unaligned_check("strb", val, addr)
318
319#define put32t_unaligned_check(val,addr) \
320 __put32_unaligned_check("strbt", val, addr)
321
322static void
323do_alignment_finish_ldst(unsigned long addr, unsigned long instr, struct pt_regs *regs, union offset_union offset)
324{
325 if (!LDST_U_BIT(instr))
326 offset.un = -offset.un;
327
328 if (!LDST_P_BIT(instr))
329 addr += offset.un;
330
331 if (!LDST_P_BIT(instr) || LDST_W_BIT(instr))
332 regs->uregs[RN_BITS(instr)] = addr;
333}
334
335static int
336do_alignment_ldrhstrh(unsigned long addr, unsigned long instr, struct pt_regs *regs)
337{
338 unsigned int rd = RD_BITS(instr);
339
340 ai_half += 1;
341
342 if (user_mode(regs))
343 goto user;
344
345 if (LDST_L_BIT(instr)) {
346 unsigned long val;
347 get16_unaligned_check(val, addr);
348
349 /* signed half-word? */
350 if (instr & 0x40)
351 val = (signed long)((signed short) val);
352
353 regs->uregs[rd] = val;
354 } else
355 put16_unaligned_check(regs->uregs[rd], addr);
356
357 return TYPE_LDST;
358
359 user:
360 if (LDST_L_BIT(instr)) {
361 unsigned long val;
362 get16t_unaligned_check(val, addr);
363
364 /* signed half-word? */
365 if (instr & 0x40)
366 val = (signed long)((signed short) val);
367
368 regs->uregs[rd] = val;
369 } else
370 put16t_unaligned_check(regs->uregs[rd], addr);
371
372 return TYPE_LDST;
373
374 fault:
375 return TYPE_FAULT;
376}
377
378static int
379do_alignment_ldrdstrd(unsigned long addr, unsigned long instr,
380 struct pt_regs *regs)
381{
382 unsigned int rd = RD_BITS(instr);
383 unsigned int rd2;
384 int load;
385
386 if ((instr & 0xfe000000) == 0xe8000000) {
387 /* ARMv7 Thumb-2 32-bit LDRD/STRD */
388 rd2 = (instr >> 8) & 0xf;
389 load = !!(LDST_L_BIT(instr));
390 } else if (((rd & 1) == 1) || (rd == 14))
391 goto bad;
392 else {
393 load = ((instr & 0xf0) == 0xd0);
394 rd2 = rd + 1;
395 }
396
397 ai_dword += 1;
398
399 if (user_mode(regs))
400 goto user;
401
402 if (load) {
403 unsigned long val;
404 get32_unaligned_check(val, addr);
405 regs->uregs[rd] = val;
406 get32_unaligned_check(val, addr + 4);
407 regs->uregs[rd2] = val;
408 } else {
409 put32_unaligned_check(regs->uregs[rd], addr);
410 put32_unaligned_check(regs->uregs[rd2], addr + 4);
411 }
412
413 return TYPE_LDST;
414
415 user:
416 if (load) {
417 unsigned long val;
418 get32t_unaligned_check(val, addr);
419 regs->uregs[rd] = val;
420 get32t_unaligned_check(val, addr + 4);
421 regs->uregs[rd2] = val;
422 } else {
423 put32t_unaligned_check(regs->uregs[rd], addr);
424 put32t_unaligned_check(regs->uregs[rd2], addr + 4);
425 }
426
427 return TYPE_LDST;
428 bad:
429 return TYPE_ERROR;
430 fault:
431 return TYPE_FAULT;
432}
433
434static int
435do_alignment_ldrstr(unsigned long addr, unsigned long instr, struct pt_regs *regs)
436{
437 unsigned int rd = RD_BITS(instr);
438
439 ai_word += 1;
440
441 if ((!LDST_P_BIT(instr) && LDST_W_BIT(instr)) || user_mode(regs))
442 goto trans;
443
444 if (LDST_L_BIT(instr)) {
445 unsigned int val;
446 get32_unaligned_check(val, addr);
447 regs->uregs[rd] = val;
448 } else
449 put32_unaligned_check(regs->uregs[rd], addr);
450 return TYPE_LDST;
451
452 trans:
453 if (LDST_L_BIT(instr)) {
454 unsigned int val;
455 get32t_unaligned_check(val, addr);
456 regs->uregs[rd] = val;
457 } else
458 put32t_unaligned_check(regs->uregs[rd], addr);
459 return TYPE_LDST;
460
461 fault:
462 return TYPE_FAULT;
463}
464
465/*
466 * LDM/STM alignment handler.
467 *
468 * There are 4 variants of this instruction:
469 *
470 * B = rn pointer before instruction, A = rn pointer after instruction
471 * ------ increasing address ----->
472 * | | r0 | r1 | ... | rx | |
473 * PU = 01 B A
474 * PU = 11 B A
475 * PU = 00 A B
476 * PU = 10 A B
477 */
478static int
479do_alignment_ldmstm(unsigned long addr, unsigned long instr, struct pt_regs *regs)
480{
481 unsigned int rd, rn, correction, nr_regs, regbits;
482 unsigned long eaddr, newaddr;
483
484 if (LDM_S_BIT(instr))
485 goto bad;
486
487 correction = 4; /* processor implementation defined */
488 regs->ARM_pc += correction;
489
490 ai_multi += 1;
491
492 /* count the number of registers in the mask to be transferred */
493 nr_regs = hweight16(REGMASK_BITS(instr)) * 4;
494
495 rn = RN_BITS(instr);
496 newaddr = eaddr = regs->uregs[rn];
497
498 if (!LDST_U_BIT(instr))
499 nr_regs = -nr_regs;
500 newaddr += nr_regs;
501 if (!LDST_U_BIT(instr))
502 eaddr = newaddr;
503
504 if (LDST_P_EQ_U(instr)) /* U = P */
505 eaddr += 4;
506
507 /*
508 * For alignment faults on the ARM922T/ARM920T the MMU makes
509 * the FSR (and hence addr) equal to the updated base address
510 * of the multiple access rather than the restored value.
511 * Switch this message off if we've got a ARM92[02], otherwise
512 * [ls]dm alignment faults are noisy!
513 */
514#if !(defined CONFIG_CPU_ARM922T) && !(defined CONFIG_CPU_ARM920T)
515 /*
516 * This is a "hint" - we already have eaddr worked out by the
517 * processor for us.
518 */
519 if (addr != eaddr) {
520 printk(KERN_ERR "LDMSTM: PC = %08lx, instr = %08lx, "
521 "addr = %08lx, eaddr = %08lx\n",
522 instruction_pointer(regs), instr, addr, eaddr);
523 show_regs(regs);
524 }
525#endif
526
527 if (user_mode(regs)) {
528 for (regbits = REGMASK_BITS(instr), rd = 0; regbits;
529 regbits >>= 1, rd += 1)
530 if (regbits & 1) {
531 if (LDST_L_BIT(instr)) {
532 unsigned int val;
533 get32t_unaligned_check(val, eaddr);
534 regs->uregs[rd] = val;
535 } else
536 put32t_unaligned_check(regs->uregs[rd], eaddr);
537 eaddr += 4;
538 }
539 } else {
540 for (regbits = REGMASK_BITS(instr), rd = 0; regbits;
541 regbits >>= 1, rd += 1)
542 if (regbits & 1) {
543 if (LDST_L_BIT(instr)) {
544 unsigned int val;
545 get32_unaligned_check(val, eaddr);
546 regs->uregs[rd] = val;
547 } else
548 put32_unaligned_check(regs->uregs[rd], eaddr);
549 eaddr += 4;
550 }
551 }
552
553 if (LDST_W_BIT(instr))
554 regs->uregs[rn] = newaddr;
555 if (!LDST_L_BIT(instr) || !(REGMASK_BITS(instr) & (1 << 15)))
556 regs->ARM_pc -= correction;
557 return TYPE_DONE;
558
559fault:
560 regs->ARM_pc -= correction;
561 return TYPE_FAULT;
562
563bad:
564 printk(KERN_ERR "Alignment trap: not handling ldm with s-bit set\n");
565 return TYPE_ERROR;
566}
567
568/*
569 * Convert Thumb ld/st instruction forms to equivalent ARM instructions so
570 * we can reuse ARM userland alignment fault fixups for Thumb.
571 *
572 * This implementation was initially based on the algorithm found in
573 * gdb/sim/arm/thumbemu.c. It is basically just a code reduction of same
574 * to convert only Thumb ld/st instruction forms to equivalent ARM forms.
575 *
576 * NOTES:
577 * 1. Comments below refer to ARM ARM DDI0100E Thumb Instruction sections.
578 * 2. If for some reason we're passed an non-ld/st Thumb instruction to
579 * decode, we return 0xdeadc0de. This should never happen under normal
580 * circumstances but if it does, we've got other problems to deal with
581 * elsewhere and we obviously can't fix those problems here.
582 */
583
584static unsigned long
585thumb2arm(u16 tinstr)
586{
587 u32 L = (tinstr & (1<<11)) >> 11;
588
589 switch ((tinstr & 0xf800) >> 11) {
590 /* 6.5.1 Format 1: */
591 case 0x6000 >> 11: /* 7.1.52 STR(1) */
592 case 0x6800 >> 11: /* 7.1.26 LDR(1) */
593 case 0x7000 >> 11: /* 7.1.55 STRB(1) */
594 case 0x7800 >> 11: /* 7.1.30 LDRB(1) */
595 return 0xe5800000 |
596 ((tinstr & (1<<12)) << (22-12)) | /* fixup */
597 (L<<20) | /* L==1? */
598 ((tinstr & (7<<0)) << (12-0)) | /* Rd */
599 ((tinstr & (7<<3)) << (16-3)) | /* Rn */
600 ((tinstr & (31<<6)) >> /* immed_5 */
601 (6 - ((tinstr & (1<<12)) ? 0 : 2)));
602 case 0x8000 >> 11: /* 7.1.57 STRH(1) */
603 case 0x8800 >> 11: /* 7.1.32 LDRH(1) */
604 return 0xe1c000b0 |
605 (L<<20) | /* L==1? */
606 ((tinstr & (7<<0)) << (12-0)) | /* Rd */
607 ((tinstr & (7<<3)) << (16-3)) | /* Rn */
608 ((tinstr & (7<<6)) >> (6-1)) | /* immed_5[2:0] */
609 ((tinstr & (3<<9)) >> (9-8)); /* immed_5[4:3] */
610
611 /* 6.5.1 Format 2: */
612 case 0x5000 >> 11:
613 case 0x5800 >> 11:
614 {
615 static const u32 subset[8] = {
616 0xe7800000, /* 7.1.53 STR(2) */
617 0xe18000b0, /* 7.1.58 STRH(2) */
618 0xe7c00000, /* 7.1.56 STRB(2) */
619 0xe19000d0, /* 7.1.34 LDRSB */
620 0xe7900000, /* 7.1.27 LDR(2) */
621 0xe19000b0, /* 7.1.33 LDRH(2) */
622 0xe7d00000, /* 7.1.31 LDRB(2) */
623 0xe19000f0 /* 7.1.35 LDRSH */
624 };
625 return subset[(tinstr & (7<<9)) >> 9] |
626 ((tinstr & (7<<0)) << (12-0)) | /* Rd */
627 ((tinstr & (7<<3)) << (16-3)) | /* Rn */
628 ((tinstr & (7<<6)) >> (6-0)); /* Rm */
629 }
630
631 /* 6.5.1 Format 3: */
632 case 0x4800 >> 11: /* 7.1.28 LDR(3) */
633 /* NOTE: This case is not technically possible. We're
634 * loading 32-bit memory data via PC relative
635 * addressing mode. So we can and should eliminate
636 * this case. But I'll leave it here for now.
637 */
638 return 0xe59f0000 |
639 ((tinstr & (7<<8)) << (12-8)) | /* Rd */
640 ((tinstr & 255) << (2-0)); /* immed_8 */
641
642 /* 6.5.1 Format 4: */
643 case 0x9000 >> 11: /* 7.1.54 STR(3) */
644 case 0x9800 >> 11: /* 7.1.29 LDR(4) */
645 return 0xe58d0000 |
646 (L<<20) | /* L==1? */
647 ((tinstr & (7<<8)) << (12-8)) | /* Rd */
648 ((tinstr & 255) << 2); /* immed_8 */
649
650 /* 6.6.1 Format 1: */
651 case 0xc000 >> 11: /* 7.1.51 STMIA */
652 case 0xc800 >> 11: /* 7.1.25 LDMIA */
653 {
654 u32 Rn = (tinstr & (7<<8)) >> 8;
655 u32 W = ((L<<Rn) & (tinstr&255)) ? 0 : 1<<21;
656
657 return 0xe8800000 | W | (L<<20) | (Rn<<16) |
658 (tinstr&255);
659 }
660
661 /* 6.6.1 Format 2: */
662 case 0xb000 >> 11: /* 7.1.48 PUSH */
663 case 0xb800 >> 11: /* 7.1.47 POP */
664 if ((tinstr & (3 << 9)) == 0x0400) {
665 static const u32 subset[4] = {
666 0xe92d0000, /* STMDB sp!,{registers} */
667 0xe92d4000, /* STMDB sp!,{registers,lr} */
668 0xe8bd0000, /* LDMIA sp!,{registers} */
669 0xe8bd8000 /* LDMIA sp!,{registers,pc} */
670 };
671 return subset[(L<<1) | ((tinstr & (1<<8)) >> 8)] |
672 (tinstr & 255); /* register_list */
673 }
674 /* Else fall through for illegal instruction case */
675
676 default:
677 return BAD_INSTR;
678 }
679}
680
681/*
682 * Convert Thumb-2 32 bit LDM, STM, LDRD, STRD to equivalent instruction
683 * handlable by ARM alignment handler, also find the corresponding handler,
684 * so that we can reuse ARM userland alignment fault fixups for Thumb.
685 *
686 * @pinstr: original Thumb-2 instruction; returns new handlable instruction
687 * @regs: register context.
688 * @poffset: return offset from faulted addr for later writeback
689 *
690 * NOTES:
691 * 1. Comments below refer to ARMv7 DDI0406A Thumb Instruction sections.
692 * 2. Register name Rt from ARMv7 is same as Rd from ARMv6 (Rd is Rt)
693 */
694static void *
695do_alignment_t32_to_handler(unsigned long *pinstr, struct pt_regs *regs,
696 union offset_union *poffset)
697{
698 unsigned long instr = *pinstr;
699 u16 tinst1 = (instr >> 16) & 0xffff;
700 u16 tinst2 = instr & 0xffff;
701 poffset->un = 0;
702
703 switch (tinst1 & 0xffe0) {
704 /* A6.3.5 Load/Store multiple */
705 case 0xe880: /* STM/STMIA/STMEA,LDM/LDMIA, PUSH/POP T2 */
706 case 0xe8a0: /* ...above writeback version */
707 case 0xe900: /* STMDB/STMFD, LDMDB/LDMEA */
708 case 0xe920: /* ...above writeback version */
709 /* no need offset decision since handler calculates it */
710 return do_alignment_ldmstm;
711
712 case 0xf840: /* POP/PUSH T3 (single register) */
713 if (RN_BITS(instr) == 13 && (tinst2 & 0x09ff) == 0x0904) {
714 u32 L = !!(LDST_L_BIT(instr));
715 const u32 subset[2] = {
716 0xe92d0000, /* STMDB sp!,{registers} */
717 0xe8bd0000, /* LDMIA sp!,{registers} */
718 };
719 *pinstr = subset[L] | (1<<RD_BITS(instr));
720 return do_alignment_ldmstm;
721 }
722 /* Else fall through for illegal instruction case */
723 break;
724
725 /* A6.3.6 Load/store double, STRD/LDRD(immed, lit, reg) */
726 case 0xe860:
727 case 0xe960:
728 case 0xe8e0:
729 case 0xe9e0:
730 poffset->un = (tinst2 & 0xff) << 2;
731 case 0xe940:
732 case 0xe9c0:
733 return do_alignment_ldrdstrd;
734
735 /*
736 * No need to handle load/store instructions up to word size
737 * since ARMv6 and later CPUs can perform unaligned accesses.
738 */
739 default:
740 break;
741 }
742 return NULL;
743}
744
745static int
746do_alignment(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
747{
748 union offset_union offset;
749 unsigned long instr = 0, instrptr;
750 int (*handler)(unsigned long addr, unsigned long instr, struct pt_regs *regs);
751 unsigned int type;
752 mm_segment_t fs;
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 fs = get_fs();
764 set_fs(KERNEL_DS);
765 if (thumb_mode(regs)) {
766 fault = __get_user(tinstr, (u16 *)(instrptr & ~1));
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 = __get_user(tinst2, (u16 *)(instrptr+2));
773 instr = (tinstr << 16) | tinst2;
774 thumb2_32b = 1;
775 } else {
776 isize = 2;
777 instr = thumb2arm(tinstr);
778 }
779 }
780 } else
781 fault = __get_user(instr, (u32 *)instrptr);
782 set_fs(fs);
783
784 if (fault) {
785 type = TYPE_FAULT;
786 goto bad_or_fault;
787 }
788
789 if (user_mode(regs))
790 goto user;
791
792 ai_sys += 1;
793
794 fixup:
795
796 regs->ARM_pc += isize;
797
798 switch (CODING_BITS(instr)) {
799 case 0x00000000: /* 3.13.4 load/store instruction extensions */
800 if (LDSTHD_I_BIT(instr))
801 offset.un = (instr & 0xf00) >> 4 | (instr & 15);
802 else
803 offset.un = regs->uregs[RM_BITS(instr)];
804
805 if ((instr & 0x000000f0) == 0x000000b0 || /* LDRH, STRH */
806 (instr & 0x001000f0) == 0x001000f0) /* LDRSH */
807 handler = do_alignment_ldrhstrh;
808 else if ((instr & 0x001000f0) == 0x000000d0 || /* LDRD */
809 (instr & 0x001000f0) == 0x000000f0) /* STRD */
810 handler = do_alignment_ldrdstrd;
811 else if ((instr & 0x01f00ff0) == 0x01000090) /* SWP */
812 goto swp;
813 else
814 goto bad;
815 break;
816
817 case 0x04000000: /* ldr or str immediate */
818 offset.un = OFFSET_BITS(instr);
819 handler = do_alignment_ldrstr;
820 break;
821
822 case 0x06000000: /* ldr or str register */
823 offset.un = regs->uregs[RM_BITS(instr)];
824
825 if (IS_SHIFT(instr)) {
826 unsigned int shiftval = SHIFT_BITS(instr);
827
828 switch(SHIFT_TYPE(instr)) {
829 case SHIFT_LSL:
830 offset.un <<= shiftval;
831 break;
832
833 case SHIFT_LSR:
834 offset.un >>= shiftval;
835 break;
836
837 case SHIFT_ASR:
838 offset.sn >>= shiftval;
839 break;
840
841 case SHIFT_RORRRX:
842 if (shiftval == 0) {
843 offset.un >>= 1;
844 if (regs->ARM_cpsr & PSR_C_BIT)
845 offset.un |= 1 << 31;
846 } else
847 offset.un = offset.un >> shiftval |
848 offset.un << (32 - shiftval);
849 break;
850 }
851 }
852 handler = do_alignment_ldrstr;
853 break;
854
855 case 0x08000000: /* ldm or stm, or thumb-2 32bit instruction */
856 if (thumb2_32b)
857 handler = do_alignment_t32_to_handler(&instr, regs, &offset);
858 else
859 handler = do_alignment_ldmstm;
860 break;
861
862 default:
863 goto bad;
864 }
865
866 if (!handler)
867 goto bad;
868 type = handler(addr, instr, regs);
869
870 if (type == TYPE_ERROR || type == TYPE_FAULT) {
871 regs->ARM_pc -= isize;
872 goto bad_or_fault;
873 }
874
875 if (type == TYPE_LDST)
876 do_alignment_finish_ldst(addr, instr, regs, offset);
877
878 return 0;
879
880 bad_or_fault:
881 if (type == TYPE_ERROR)
882 goto bad;
883 /*
884 * We got a fault - fix it up, or die.
885 */
886 do_bad_area(addr, fsr, regs);
887 return 0;
888
889 swp:
890 printk(KERN_ERR "Alignment trap: not handling swp instruction\n");
891
892 bad:
893 /*
894 * Oops, we didn't handle the instruction.
895 */
896 printk(KERN_ERR "Alignment trap: not handling instruction "
897 "%0*lx at [<%08lx>]\n",
898 isize << 1,
899 isize == 2 ? tinstr : instr, instrptr);
900 ai_skipped += 1;
901 return 1;
902
903 user:
904 ai_user += 1;
905
906 if (ai_usermode & UM_WARN)
907 printk("Alignment trap: %s (%d) PC=0x%08lx Instr=0x%0*lx "
908 "Address=0x%08lx FSR 0x%03x\n", current->comm,
909 task_pid_nr(current), instrptr,
910 isize << 1,
911 isize == 2 ? tinstr : instr,
912 addr, fsr);
913
914 if (ai_usermode & UM_FIXUP)
915 goto fixup;
916
917 if (ai_usermode & UM_SIGNAL) {
918 siginfo_t si;
919
920 si.si_signo = SIGBUS;
921 si.si_errno = 0;
922 si.si_code = BUS_ADRALN;
923 si.si_addr = (void __user *)addr;
924
925 force_sig_info(si.si_signo, &si, current);
926 } else {
927 /*
928 * We're about to disable the alignment trap and return to
929 * user space. But if an interrupt occurs before actually
930 * reaching user space, then the IRQ vector entry code will
931 * notice that we were still in kernel space and therefore
932 * the alignment trap won't be re-enabled in that case as it
933 * is presumed to be always on from kernel space.
934 * Let's prevent that race by disabling interrupts here (they
935 * are disabled on the way back to user space anyway in
936 * entry-common.S) and disable the alignment trap only if
937 * there is no work pending for this thread.
938 */
939 raw_local_irq_disable();
940 if (!(current_thread_info()->flags & _TIF_WORK_MASK))
941 set_cr(cr_no_alignment);
942 }
943
944 return 0;
945}
946
947/*
948 * This needs to be done after sysctl_init, otherwise sys/ will be
949 * overwritten. Actually, this shouldn't be in sys/ at all since
950 * it isn't a sysctl, and it doesn't contain sysctl information.
951 * We now locate it in /proc/cpu/alignment instead.
952 */
953static int __init alignment_init(void)
954{
955#ifdef CONFIG_PROC_FS
956 struct proc_dir_entry *res;
957
958 res = proc_create("cpu/alignment", S_IWUSR | S_IRUGO, NULL,
959 &alignment_proc_fops);
960 if (!res)
961 return -ENOMEM;
962#endif
963
964 if (cpu_is_v6_unaligned()) {
965 cr_alignment &= ~CR_A;
966 cr_no_alignment &= ~CR_A;
967 set_cr(cr_alignment);
968 ai_usermode = safe_usermode(ai_usermode, false);
969 }
970
971 hook_fault_code(1, do_alignment, SIGBUS, BUS_ADRALN,
972 "alignment exception");
973
974 /*
975 * ARMv6K and ARMv7 use fault status 3 (0b00011) as Access Flag section
976 * fault, not as alignment error.
977 *
978 * TODO: handle ARMv6K properly. Runtime check for 'K' extension is
979 * needed.
980 */
981 if (cpu_architecture() <= CPU_ARCH_ARMv6) {
982 hook_fault_code(3, do_alignment, SIGBUS, BUS_ADRALN,
983 "alignment exception");
984 }
985
986 return 0;
987}
988
989fs_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 proc_ops alignment_proc_ops = {
166 .proc_open = alignment_proc_open,
167 .proc_read = seq_read,
168 .proc_lseek = seq_lseek,
169 .proc_release = single_release,
170 .proc_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 fallthrough; /* 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 fallthrough;
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 = get_kernel_nofault(instr, ip);
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 = get_kernel_nofault(instr, ip);
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 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 if (thumb_mode(regs))
939 regs->ARM_cpsr = it_advance(regs->ARM_cpsr);
940
941 return 0;
942
943 bad_or_fault:
944 if (type == TYPE_ERROR)
945 goto bad;
946 /*
947 * We got a fault - fix it up, or die.
948 */
949 do_bad_area(addr, fsr, regs);
950 return 0;
951
952 swp:
953 pr_err("Alignment trap: not handling swp instruction\n");
954
955 bad:
956 /*
957 * Oops, we didn't handle the instruction.
958 */
959 pr_err("Alignment trap: not handling instruction "
960 "%0*x at [<%08lx>]\n",
961 isize << 1,
962 isize == 2 ? tinstr : instr, instrptr);
963 ai_skipped += 1;
964 return 1;
965
966 user:
967 ai_user += 1;
968
969 if (ai_usermode & UM_WARN)
970 printk("Alignment trap: %s (%d) PC=0x%08lx Instr=0x%0*x "
971 "Address=0x%08lx FSR 0x%03x\n", current->comm,
972 task_pid_nr(current), instrptr,
973 isize << 1,
974 isize == 2 ? tinstr : instr,
975 addr, fsr);
976
977 if (ai_usermode & UM_FIXUP)
978 goto fixup;
979
980 if (ai_usermode & UM_SIGNAL) {
981 force_sig_fault(SIGBUS, BUS_ADRALN, (void __user *)addr);
982 } else {
983 /*
984 * We're about to disable the alignment trap and return to
985 * user space. But if an interrupt occurs before actually
986 * reaching user space, then the IRQ vector entry code will
987 * notice that we were still in kernel space and therefore
988 * the alignment trap won't be re-enabled in that case as it
989 * is presumed to be always on from kernel space.
990 * Let's prevent that race by disabling interrupts here (they
991 * are disabled on the way back to user space anyway in
992 * entry-common.S) and disable the alignment trap only if
993 * there is no work pending for this thread.
994 */
995 raw_local_irq_disable();
996 if (!(read_thread_flags() & _TIF_WORK_MASK))
997 set_cr(cr_no_alignment);
998 }
999
1000 return 0;
1001}
1002
1003static int __init noalign_setup(char *__unused)
1004{
1005 set_cr(__clear_cr(CR_A));
1006 return 1;
1007}
1008__setup("noalign", noalign_setup);
1009
1010/*
1011 * This needs to be done after sysctl_init_bases(), otherwise sys/ will be
1012 * overwritten. Actually, this shouldn't be in sys/ at all since
1013 * it isn't a sysctl, and it doesn't contain sysctl information.
1014 * We now locate it in /proc/cpu/alignment instead.
1015 */
1016static int __init alignment_init(void)
1017{
1018#ifdef CONFIG_PROC_FS
1019 struct proc_dir_entry *res;
1020
1021 res = proc_create("cpu/alignment", S_IWUSR | S_IRUGO, NULL,
1022 &alignment_proc_ops);
1023 if (!res)
1024 return -ENOMEM;
1025#endif
1026
1027 if (cpu_is_v6_unaligned()) {
1028 set_cr(__clear_cr(CR_A));
1029 ai_usermode = safe_usermode(ai_usermode, false);
1030 }
1031
1032 cr_no_alignment = get_cr() & ~CR_A;
1033
1034 hook_fault_code(FAULT_CODE_ALIGNMENT, do_alignment, SIGBUS, BUS_ADRALN,
1035 "alignment exception");
1036
1037 /*
1038 * ARMv6K and ARMv7 use fault status 3 (0b00011) as Access Flag section
1039 * fault, not as alignment error.
1040 *
1041 * TODO: handle ARMv6K properly. Runtime check for 'K' extension is
1042 * needed.
1043 */
1044 if (cpu_architecture() <= CPU_ARCH_ARMv6) {
1045 hook_fault_code(3, do_alignment, SIGBUS, BUS_ADRALN,
1046 "alignment exception");
1047 }
1048
1049 return 0;
1050}
1051
1052fs_initcall(alignment_init);