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