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