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[linux-2.6/next.git] / arch / arm / mm / alignment.c
blob724ba3bce72c952ff44645d2a50e5566b568c943
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/unaligned.h>
26
27 #include "fault.h"
28
29 /*
30 * 32-bit misaligned trap handler (c) 1998 San Mehat (CCC) -July 1998
31 * /proc/sys/debug/alignment, modified and integrated into
32 * Linux 2.1 by Russell King
33 *
34 * Speed optimisations and better fault handling by Russell King.
35 *
36 * *** NOTE ***
37 * This code is not portable to processors with late data abort handling.
38 */
39 #define CODING_BITS(i) (i & 0x0e000000)
40
41 #define LDST_I_BIT(i) (i & (1 << 26)) /* Immediate constant */
42 #define LDST_P_BIT(i) (i & (1 << 24)) /* Preindex */
43 #define LDST_U_BIT(i) (i & (1 << 23)) /* Add offset */
44 #define LDST_W_BIT(i) (i & (1 << 21)) /* Writeback */
45 #define LDST_L_BIT(i) (i & (1 << 20)) /* Load */
46
47 #define LDST_P_EQ_U(i) ((((i) ^ ((i) >> 1)) & (1 << 23)) == 0)
48
49 #define LDSTHD_I_BIT(i) (i & (1 << 22)) /* double/half-word immed */
50 #define LDM_S_BIT(i) (i & (1 << 22)) /* write CPSR from SPSR */
51
52 #define RN_BITS(i) ((i >> 16) & 15) /* Rn */
53 #define RD_BITS(i) ((i >> 12) & 15) /* Rd */
54 #define RM_BITS(i) (i & 15) /* Rm */
55
56 #define REGMASK_BITS(i) (i & 0xffff)
57 #define OFFSET_BITS(i) (i & 0x0fff)
58
59 #define IS_SHIFT(i) (i & 0x0ff0)
60 #define SHIFT_BITS(i) ((i >> 7) & 0x1f)
61 #define SHIFT_TYPE(i) (i & 0x60)
62 #define SHIFT_LSL 0x00
63 #define SHIFT_LSR 0x20
64 #define SHIFT_ASR 0x40
65 #define SHIFT_RORRRX 0x60
66
67 #define BAD_INSTR 0xdeadc0de
68
69 /* Thumb-2 32 bit format per ARMv7 DDI0406A A6.3, either f800h,e800h,f800h */
70 #define IS_T32(hi16) \
71 (((hi16) & 0xe000) == 0xe000 && ((hi16) & 0x1800))
72
73 static unsigned long ai_user;
74 static unsigned long ai_sys;
75 static unsigned long ai_skipped;
76 static unsigned long ai_half;
77 static unsigned long ai_word;
78 static unsigned long ai_dword;
79 static unsigned long ai_multi;
80 static int ai_usermode;
81
82 core_param(alignment, ai_usermode, int, 0600);
83
84 #define UM_WARN (1 << 0)
85 #define UM_FIXUP (1 << 1)
86 #define UM_SIGNAL (1 << 2)
87
88 #ifdef CONFIG_PROC_FS
89 static const char *usermode_action[] = {
90 "ignored",
91 "warn",
92 "fixup",
93 "fixup+warn",
94 "signal",
95 "signal+warn"
96 };
97
98 static int alignment_proc_show(struct seq_file *m, void *v)
99 {
100 seq_printf(m, "User:\t\t%lu\n", ai_user);
101 seq_printf(m, "System:\t\t%lu\n", ai_sys);
102 seq_printf(m, "Skipped:\t%lu\n", ai_skipped);
103 seq_printf(m, "Half:\t\t%lu\n", ai_half);
104 seq_printf(m, "Word:\t\t%lu\n", ai_word);
105 if (cpu_architecture() >= CPU_ARCH_ARMv5TE)
106 seq_printf(m, "DWord:\t\t%lu\n", ai_dword);
107 seq_printf(m, "Multi:\t\t%lu\n", ai_multi);
108 seq_printf(m, "User faults:\t%i (%s)\n", ai_usermode,
109 usermode_action[ai_usermode]);
110
111 return 0;
112 }
113
114 static int alignment_proc_open(struct inode *inode, struct file *file)
115 {
116 return single_open(file, alignment_proc_show, NULL);
117 }
118
119 static ssize_t alignment_proc_write(struct file *file, const char __user *buffer,
120 size_t count, loff_t *pos)
121 {
122 char mode;
123
124 if (count > 0) {
125 if (get_user(mode, buffer))
126 return -EFAULT;
127 if (mode >= '0' && mode <= '5')
128 ai_usermode = mode - '0';
129 }
130 return count;
131 }
132
133 static const struct file_operations alignment_proc_fops = {
134 .open = alignment_proc_open,
135 .read = seq_read,
136 .llseek = seq_lseek,
137 .release = single_release,
138 .write = alignment_proc_write,
139 };
140 #endif /* CONFIG_PROC_FS */
141
142 union offset_union {
143 unsigned long un;
144 signed long sn;
145 };
146
147 #define TYPE_ERROR 0
148 #define TYPE_FAULT 1
149 #define TYPE_LDST 2
150 #define TYPE_DONE 3
151
152 #ifdef __ARMEB__
153 #define BE 1
154 #define FIRST_BYTE_16 "mov %1, %1, ror #8\n"
155 #define FIRST_BYTE_32 "mov %1, %1, ror #24\n"
156 #define NEXT_BYTE "ror #24"
157 #else
158 #define BE 0
159 #define FIRST_BYTE_16
160 #define FIRST_BYTE_32
161 #define NEXT_BYTE "lsr #8"
162 #endif
163
164 #define __get8_unaligned_check(ins,val,addr,err) \
165 __asm__( \
166 ARM( "1: "ins" %1, [%2], #1\n" ) \
167 THUMB( "1: "ins" %1, [%2]\n" ) \
168 THUMB( " add %2, %2, #1\n" ) \
169 "2:\n" \
170 " .pushsection .fixup,\"ax\"\n" \
171 " .align 2\n" \
172 "3: mov %0, #1\n" \
173 " b 2b\n" \
174 " .popsection\n" \
175 " .pushsection __ex_table,\"a\"\n" \
176 " .align 3\n" \
177 " .long 1b, 3b\n" \
178 " .popsection\n" \
179 : "=r" (err), "=&r" (val), "=r" (addr) \
180 : "0" (err), "2" (addr))
181
182 #define __get16_unaligned_check(ins,val,addr) \
183 do { \
184 unsigned int err = 0, v, a = addr; \
185 __get8_unaligned_check(ins,v,a,err); \
186 val = v << ((BE) ? 8 : 0); \
187 __get8_unaligned_check(ins,v,a,err); \
188 val |= v << ((BE) ? 0 : 8); \
189 if (err) \
190 goto fault; \
191 } while (0)
192
193 #define get16_unaligned_check(val,addr) \
194 __get16_unaligned_check("ldrb",val,addr)
195
196 #define get16t_unaligned_check(val,addr) \
197 __get16_unaligned_check("ldrbt",val,addr)
198
199 #define __get32_unaligned_check(ins,val,addr) \
200 do { \
201 unsigned int err = 0, v, a = addr; \
202 __get8_unaligned_check(ins,v,a,err); \
203 val = v << ((BE) ? 24 : 0); \
204 __get8_unaligned_check(ins,v,a,err); \
205 val |= v << ((BE) ? 16 : 8); \
206 __get8_unaligned_check(ins,v,a,err); \
207 val |= v << ((BE) ? 8 : 16); \
208 __get8_unaligned_check(ins,v,a,err); \
209 val |= v << ((BE) ? 0 : 24); \
210 if (err) \
211 goto fault; \
212 } while (0)
213
214 #define get32_unaligned_check(val,addr) \
215 __get32_unaligned_check("ldrb",val,addr)
216
217 #define get32t_unaligned_check(val,addr) \
218 __get32_unaligned_check("ldrbt",val,addr)
219
220 #define __put16_unaligned_check(ins,val,addr) \
221 do { \
222 unsigned int err = 0, v = val, a = addr; \
223 __asm__( FIRST_BYTE_16 \
224 ARM( "1: "ins" %1, [%2], #1\n" ) \
225 THUMB( "1: "ins" %1, [%2]\n" ) \
226 THUMB( " add %2, %2, #1\n" ) \
227 " mov %1, %1, "NEXT_BYTE"\n" \
228 "2: "ins" %1, [%2]\n" \
229 "3:\n" \
230 " .pushsection .fixup,\"ax\"\n" \
231 " .align 2\n" \
232 "4: mov %0, #1\n" \
233 " b 3b\n" \
234 " .popsection\n" \
235 " .pushsection __ex_table,\"a\"\n" \
236 " .align 3\n" \
237 " .long 1b, 4b\n" \
238 " .long 2b, 4b\n" \
239 " .popsection\n" \
240 : "=r" (err), "=&r" (v), "=&r" (a) \
241 : "0" (err), "1" (v), "2" (a)); \
242 if (err) \
243 goto fault; \
244 } while (0)
245
246 #define put16_unaligned_check(val,addr) \
247 __put16_unaligned_check("strb",val,addr)
248
249 #define put16t_unaligned_check(val,addr) \
250 __put16_unaligned_check("strbt",val,addr)
251
252 #define __put32_unaligned_check(ins,val,addr) \
253 do { \
254 unsigned int err = 0, v = val, a = addr; \
255 __asm__( FIRST_BYTE_32 \
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 ARM( "2: "ins" %1, [%2], #1\n" ) \
261 THUMB( "2: "ins" %1, [%2]\n" ) \
262 THUMB( " add %2, %2, #1\n" ) \
263 " mov %1, %1, "NEXT_BYTE"\n" \
264 ARM( "3: "ins" %1, [%2], #1\n" ) \
265 THUMB( "3: "ins" %1, [%2]\n" ) \
266 THUMB( " add %2, %2, #1\n" ) \
267 " mov %1, %1, "NEXT_BYTE"\n" \
268 "4: "ins" %1, [%2]\n" \
269 "5:\n" \
270 " .pushsection .fixup,\"ax\"\n" \
271 " .align 2\n" \
272 "6: mov %0, #1\n" \
273 " b 5b\n" \
274 " .popsection\n" \
275 " .pushsection __ex_table,\"a\"\n" \
276 " .align 3\n" \
277 " .long 1b, 6b\n" \
278 " .long 2b, 6b\n" \
279 " .long 3b, 6b\n" \
280 " .long 4b, 6b\n" \
281 " .popsection\n" \
282 : "=r" (err), "=&r" (v), "=&r" (a) \
283 : "0" (err), "1" (v), "2" (a)); \
284 if (err) \
285 goto fault; \
286 } while (0)
287
288 #define put32_unaligned_check(val,addr) \
289 __put32_unaligned_check("strb", val, addr)
290
291 #define put32t_unaligned_check(val,addr) \
292 __put32_unaligned_check("strbt", val, addr)
293
294 static void
295 do_alignment_finish_ldst(unsigned long addr, unsigned long instr, struct pt_regs *regs, union offset_union offset)
296 {
297 if (!LDST_U_BIT(instr))
298 offset.un = -offset.un;
299
300 if (!LDST_P_BIT(instr))
301 addr += offset.un;
302
303 if (!LDST_P_BIT(instr) || LDST_W_BIT(instr))
304 regs->uregs[RN_BITS(instr)] = addr;
305 }
306
307 static int
308 do_alignment_ldrhstrh(unsigned long addr, unsigned long instr, struct pt_regs *regs)
309 {
310 unsigned int rd = RD_BITS(instr);
311
312 ai_half += 1;
313
314 if (user_mode(regs))
315 goto user;
316
317 if (LDST_L_BIT(instr)) {
318 unsigned long val;
319 get16_unaligned_check(val, addr);
320
321 /* signed half-word? */
322 if (instr & 0x40)
323 val = (signed long)((signed short) val);
324
325 regs->uregs[rd] = val;
326 } else
327 put16_unaligned_check(regs->uregs[rd], addr);
328
329 return TYPE_LDST;
330
331 user:
332 if (LDST_L_BIT(instr)) {
333 unsigned long val;
334 get16t_unaligned_check(val, addr);
335
336 /* signed half-word? */
337 if (instr & 0x40)
338 val = (signed long)((signed short) val);
339
340 regs->uregs[rd] = val;
341 } else
342 put16t_unaligned_check(regs->uregs[rd], addr);
343
344 return TYPE_LDST;
345
346 fault:
347 return TYPE_FAULT;
348 }
349
350 static int
351 do_alignment_ldrdstrd(unsigned long addr, unsigned long instr,
352 struct pt_regs *regs)
353 {
354 unsigned int rd = RD_BITS(instr);
355 unsigned int rd2;
356 int load;
357
358 if ((instr & 0xfe000000) == 0xe8000000) {
359 /* ARMv7 Thumb-2 32-bit LDRD/STRD */
360 rd2 = (instr >> 8) & 0xf;
361 load = !!(LDST_L_BIT(instr));
362 } else if (((rd & 1) == 1) || (rd == 14))
363 goto bad;
364 else {
365 load = ((instr & 0xf0) == 0xd0);
366 rd2 = rd + 1;
367 }
368
369 ai_dword += 1;
370
371 if (user_mode(regs))
372 goto user;
373
374 if (load) {
375 unsigned long val;
376 get32_unaligned_check(val, addr);
377 regs->uregs[rd] = val;
378 get32_unaligned_check(val, addr + 4);
379 regs->uregs[rd2] = val;
380 } else {
381 put32_unaligned_check(regs->uregs[rd], addr);
382 put32_unaligned_check(regs->uregs[rd2], addr + 4);
383 }
384
385 return TYPE_LDST;
386
387 user:
388 if (load) {
389 unsigned long val;
390 get32t_unaligned_check(val, addr);
391 regs->uregs[rd] = val;
392 get32t_unaligned_check(val, addr + 4);
393 regs->uregs[rd2] = val;
394 } else {
395 put32t_unaligned_check(regs->uregs[rd], addr);
396 put32t_unaligned_check(regs->uregs[rd2], addr + 4);
397 }
398
399 return TYPE_LDST;
400 bad:
401 return TYPE_ERROR;
402 fault:
403 return TYPE_FAULT;
404 }
405
406 static int
407 do_alignment_ldrstr(unsigned long addr, unsigned long instr, struct pt_regs *regs)
408 {
409 unsigned int rd = RD_BITS(instr);
410
411 ai_word += 1;
412
413 if ((!LDST_P_BIT(instr) && LDST_W_BIT(instr)) || user_mode(regs))
414 goto trans;
415
416 if (LDST_L_BIT(instr)) {
417 unsigned int val;
418 get32_unaligned_check(val, addr);
419 regs->uregs[rd] = val;
420 } else
421 put32_unaligned_check(regs->uregs[rd], addr);
422 return TYPE_LDST;
423
424 trans:
425 if (LDST_L_BIT(instr)) {
426 unsigned int val;
427 get32t_unaligned_check(val, addr);
428 regs->uregs[rd] = val;
429 } else
430 put32t_unaligned_check(regs->uregs[rd], addr);
431 return TYPE_LDST;
432
433 fault:
434 return TYPE_FAULT;
435 }
436
437 /*
438 * LDM/STM alignment handler.
439 *
440 * There are 4 variants of this instruction:
441 *
442 * B = rn pointer before instruction, A = rn pointer after instruction
443 * ------ increasing address ----->
444 * | | r0 | r1 | ... | rx | |
445 * PU = 01 B A
446 * PU = 11 B A
447 * PU = 00 A B
448 * PU = 10 A B
449 */
450 static int
451 do_alignment_ldmstm(unsigned long addr, unsigned long instr, struct pt_regs *regs)
452 {
453 unsigned int rd, rn, correction, nr_regs, regbits;
454 unsigned long eaddr, newaddr;
455
456 if (LDM_S_BIT(instr))
457 goto bad;
458
459 correction = 4; /* processor implementation defined */
460 regs->ARM_pc += correction;
461
462 ai_multi += 1;
463
464 /* count the number of registers in the mask to be transferred */
465 nr_regs = hweight16(REGMASK_BITS(instr)) * 4;
466
467 rn = RN_BITS(instr);
468 newaddr = eaddr = regs->uregs[rn];
469
470 if (!LDST_U_BIT(instr))
471 nr_regs = -nr_regs;
472 newaddr += nr_regs;
473 if (!LDST_U_BIT(instr))
474 eaddr = newaddr;
475
476 if (LDST_P_EQ_U(instr)) /* U = P */
477 eaddr += 4;
478
479 /*
480 * For alignment faults on the ARM922T/ARM920T the MMU makes
481 * the FSR (and hence addr) equal to the updated base address
482 * of the multiple access rather than the restored value.
483 * Switch this message off if we've got a ARM92[02], otherwise
484 * [ls]dm alignment faults are noisy!
485 */
486 #if !(defined CONFIG_CPU_ARM922T) && !(defined CONFIG_CPU_ARM920T)
487 /*
488 * This is a "hint" - we already have eaddr worked out by the
489 * processor for us.
490 */
491 if (addr != eaddr) {
492 printk(KERN_ERR "LDMSTM: PC = %08lx, instr = %08lx, "
493 "addr = %08lx, eaddr = %08lx\n",
494 instruction_pointer(regs), instr, addr, eaddr);
495 show_regs(regs);
496 }
497 #endif
498
499 if (user_mode(regs)) {
500 for (regbits = REGMASK_BITS(instr), rd = 0; regbits;
501 regbits >>= 1, rd += 1)
502 if (regbits & 1) {
503 if (LDST_L_BIT(instr)) {
504 unsigned int val;
505 get32t_unaligned_check(val, eaddr);
506 regs->uregs[rd] = val;
507 } else
508 put32t_unaligned_check(regs->uregs[rd], eaddr);
509 eaddr += 4;
510 }
511 } else {
512 for (regbits = REGMASK_BITS(instr), rd = 0; regbits;
513 regbits >>= 1, rd += 1)
514 if (regbits & 1) {
515 if (LDST_L_BIT(instr)) {
516 unsigned int val;
517 get32_unaligned_check(val, eaddr);
518 regs->uregs[rd] = val;
519 } else
520 put32_unaligned_check(regs->uregs[rd], eaddr);
521 eaddr += 4;
522 }
523 }
524
525 if (LDST_W_BIT(instr))
526 regs->uregs[rn] = newaddr;
527 if (!LDST_L_BIT(instr) || !(REGMASK_BITS(instr) & (1 << 15)))
528 regs->ARM_pc -= correction;
529 return TYPE_DONE;
530
531 fault:
532 regs->ARM_pc -= correction;
533 return TYPE_FAULT;
534
535 bad:
536 printk(KERN_ERR "Alignment trap: not handling ldm with s-bit set\n");
537 return TYPE_ERROR;
538 }
539
540 /*
541 * Convert Thumb ld/st instruction forms to equivalent ARM instructions so
542 * we can reuse ARM userland alignment fault fixups for Thumb.
543 *
544 * This implementation was initially based on the algorithm found in
545 * gdb/sim/arm/thumbemu.c. It is basically just a code reduction of same
546 * to convert only Thumb ld/st instruction forms to equivalent ARM forms.
547 *
548 * NOTES:
549 * 1. Comments below refer to ARM ARM DDI0100E Thumb Instruction sections.
550 * 2. If for some reason we're passed an non-ld/st Thumb instruction to
551 * decode, we return 0xdeadc0de. This should never happen under normal
552 * circumstances but if it does, we've got other problems to deal with
553 * elsewhere and we obviously can't fix those problems here.
554 */
555
556 static unsigned long
557 thumb2arm(u16 tinstr)
558 {
559 u32 L = (tinstr & (1<<11)) >> 11;
560
561 switch ((tinstr & 0xf800) >> 11) {
562 /* 6.5.1 Format 1: */
563 case 0x6000 >> 11: /* 7.1.52 STR(1) */
564 case 0x6800 >> 11: /* 7.1.26 LDR(1) */
565 case 0x7000 >> 11: /* 7.1.55 STRB(1) */
566 case 0x7800 >> 11: /* 7.1.30 LDRB(1) */
567 return 0xe5800000 |
568 ((tinstr & (1<<12)) << (22-12)) | /* fixup */
569 (L<<20) | /* L==1? */
570 ((tinstr & (7<<0)) << (12-0)) | /* Rd */
571 ((tinstr & (7<<3)) << (16-3)) | /* Rn */
572 ((tinstr & (31<<6)) >> /* immed_5 */
573 (6 - ((tinstr & (1<<12)) ? 0 : 2)));
574 case 0x8000 >> 11: /* 7.1.57 STRH(1) */
575 case 0x8800 >> 11: /* 7.1.32 LDRH(1) */
576 return 0xe1c000b0 |
577 (L<<20) | /* L==1? */
578 ((tinstr & (7<<0)) << (12-0)) | /* Rd */
579 ((tinstr & (7<<3)) << (16-3)) | /* Rn */
580 ((tinstr & (7<<6)) >> (6-1)) | /* immed_5[2:0] */
581 ((tinstr & (3<<9)) >> (9-8)); /* immed_5[4:3] */
582
583 /* 6.5.1 Format 2: */
584 case 0x5000 >> 11:
585 case 0x5800 >> 11:
586 {
587 static const u32 subset[8] = {
588 0xe7800000, /* 7.1.53 STR(2) */
589 0xe18000b0, /* 7.1.58 STRH(2) */
590 0xe7c00000, /* 7.1.56 STRB(2) */
591 0xe19000d0, /* 7.1.34 LDRSB */
592 0xe7900000, /* 7.1.27 LDR(2) */
593 0xe19000b0, /* 7.1.33 LDRH(2) */
594 0xe7d00000, /* 7.1.31 LDRB(2) */
595 0xe19000f0 /* 7.1.35 LDRSH */
596 };
597 return subset[(tinstr & (7<<9)) >> 9] |
598 ((tinstr & (7<<0)) << (12-0)) | /* Rd */
599 ((tinstr & (7<<3)) << (16-3)) | /* Rn */
600 ((tinstr & (7<<6)) >> (6-0)); /* Rm */
601 }
602
603 /* 6.5.1 Format 3: */
604 case 0x4800 >> 11: /* 7.1.28 LDR(3) */
605 /* NOTE: This case is not technically possible. We're
606 * loading 32-bit memory data via PC relative
607 * addressing mode. So we can and should eliminate
608 * this case. But I'll leave it here for now.
609 */
610 return 0xe59f0000 |
611 ((tinstr & (7<<8)) << (12-8)) | /* Rd */
612 ((tinstr & 255) << (2-0)); /* immed_8 */
613
614 /* 6.5.1 Format 4: */
615 case 0x9000 >> 11: /* 7.1.54 STR(3) */
616 case 0x9800 >> 11: /* 7.1.29 LDR(4) */
617 return 0xe58d0000 |
618 (L<<20) | /* L==1? */
619 ((tinstr & (7<<8)) << (12-8)) | /* Rd */
620 ((tinstr & 255) << 2); /* immed_8 */
621
622 /* 6.6.1 Format 1: */
623 case 0xc000 >> 11: /* 7.1.51 STMIA */
624 case 0xc800 >> 11: /* 7.1.25 LDMIA */
625 {
626 u32 Rn = (tinstr & (7<<8)) >> 8;
627 u32 W = ((L<<Rn) & (tinstr&255)) ? 0 : 1<<21;
628
629 return 0xe8800000 | W | (L<<20) | (Rn<<16) |
630 (tinstr&255);
631 }
632
633 /* 6.6.1 Format 2: */
634 case 0xb000 >> 11: /* 7.1.48 PUSH */
635 case 0xb800 >> 11: /* 7.1.47 POP */
636 if ((tinstr & (3 << 9)) == 0x0400) {
637 static const u32 subset[4] = {
638 0xe92d0000, /* STMDB sp!,{registers} */
639 0xe92d4000, /* STMDB sp!,{registers,lr} */
640 0xe8bd0000, /* LDMIA sp!,{registers} */
641 0xe8bd8000 /* LDMIA sp!,{registers,pc} */
642 };
643 return subset[(L<<1) | ((tinstr & (1<<8)) >> 8)] |
644 (tinstr & 255); /* register_list */
645 }
646 /* Else fall through for illegal instruction case */
647
648 default:
649 return BAD_INSTR;
650 }
651 }
652
653 /*
654 * Convert Thumb-2 32 bit LDM, STM, LDRD, STRD to equivalent instruction
655 * handlable by ARM alignment handler, also find the corresponding handler,
656 * so that we can reuse ARM userland alignment fault fixups for Thumb.
657 *
658 * @pinstr: original Thumb-2 instruction; returns new handlable instruction
659 * @regs: register context.
660 * @poffset: return offset from faulted addr for later writeback
661 *
662 * NOTES:
663 * 1. Comments below refer to ARMv7 DDI0406A Thumb Instruction sections.
664 * 2. Register name Rt from ARMv7 is same as Rd from ARMv6 (Rd is Rt)
665 */
666 static void *
667 do_alignment_t32_to_handler(unsigned long *pinstr, struct pt_regs *regs,
668 union offset_union *poffset)
669 {
670 unsigned long instr = *pinstr;
671 u16 tinst1 = (instr >> 16) & 0xffff;
672 u16 tinst2 = instr & 0xffff;
673 poffset->un = 0;
674
675 switch (tinst1 & 0xffe0) {
676 /* A6.3.5 Load/Store multiple */
677 case 0xe880: /* STM/STMIA/STMEA,LDM/LDMIA, PUSH/POP T2 */
678 case 0xe8a0: /* ...above writeback version */
679 case 0xe900: /* STMDB/STMFD, LDMDB/LDMEA */
680 case 0xe920: /* ...above writeback version */
681 /* no need offset decision since handler calculates it */
682 return do_alignment_ldmstm;
683
684 case 0xf840: /* POP/PUSH T3 (single register) */
685 if (RN_BITS(instr) == 13 && (tinst2 & 0x09ff) == 0x0904) {
686 u32 L = !!(LDST_L_BIT(instr));
687 const u32 subset[2] = {
688 0xe92d0000, /* STMDB sp!,{registers} */
689 0xe8bd0000, /* LDMIA sp!,{registers} */
690 };
691 *pinstr = subset[L] | (1<<RD_BITS(instr));
692 return do_alignment_ldmstm;
693 }
694 /* Else fall through for illegal instruction case */
695 break;
696
697 /* A6.3.6 Load/store double, STRD/LDRD(immed, lit, reg) */
698 case 0xe860:
699 case 0xe960:
700 case 0xe8e0:
701 case 0xe9e0:
702 poffset->un = (tinst2 & 0xff) << 2;
703 case 0xe940:
704 case 0xe9c0:
705 return do_alignment_ldrdstrd;
706
707 /*
708 * No need to handle load/store instructions up to word size
709 * since ARMv6 and later CPUs can perform unaligned accesses.
710 */
711 default:
712 break;
713 }
714 return NULL;
715 }
716
717 static int
718 do_alignment(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
719 {
720 union offset_union offset;
721 unsigned long instr = 0, instrptr;
722 int (*handler)(unsigned long addr, unsigned long instr, struct pt_regs *regs);
723 unsigned int type;
724 mm_segment_t fs;
725 unsigned int fault;
726 u16 tinstr = 0;
727 int isize = 4;
728 int thumb2_32b = 0;
729
730 instrptr = instruction_pointer(regs);
731
732 fs = get_fs();
733 set_fs(KERNEL_DS);
734 if (thumb_mode(regs)) {
735 fault = __get_user(tinstr, (u16 *)(instrptr & ~1));
736 if (!fault) {
737 if (cpu_architecture() >= CPU_ARCH_ARMv7 &&
738 IS_T32(tinstr)) {
739 /* Thumb-2 32-bit */
740 u16 tinst2 = 0;
741 fault = __get_user(tinst2, (u16 *)(instrptr+2));
742 instr = (tinstr << 16) | tinst2;
743 thumb2_32b = 1;
744 } else {
745 isize = 2;
746 instr = thumb2arm(tinstr);
747 }
748 }
749 } else
750 fault = __get_user(instr, (u32 *)instrptr);
751 set_fs(fs);
752
753 if (fault) {
754 type = TYPE_FAULT;
755 goto bad_or_fault;
756 }
757
758 if (user_mode(regs))
759 goto user;
760
761 ai_sys += 1;
762
763 fixup:
764
765 regs->ARM_pc += isize;
766
767 switch (CODING_BITS(instr)) {
768 case 0x00000000: /* 3.13.4 load/store instruction extensions */
769 if (LDSTHD_I_BIT(instr))
770 offset.un = (instr & 0xf00) >> 4 | (instr & 15);
771 else
772 offset.un = regs->uregs[RM_BITS(instr)];
773
774 if ((instr & 0x000000f0) == 0x000000b0 || /* LDRH, STRH */
775 (instr & 0x001000f0) == 0x001000f0) /* LDRSH */
776 handler = do_alignment_ldrhstrh;
777 else if ((instr & 0x001000f0) == 0x000000d0 || /* LDRD */
778 (instr & 0x001000f0) == 0x000000f0) /* STRD */
779 handler = do_alignment_ldrdstrd;
780 else if ((instr & 0x01f00ff0) == 0x01000090) /* SWP */
781 goto swp;
782 else
783 goto bad;
784 break;
785
786 case 0x04000000: /* ldr or str immediate */
787 offset.un = OFFSET_BITS(instr);
788 handler = do_alignment_ldrstr;
789 break;
790
791 case 0x06000000: /* ldr or str register */
792 offset.un = regs->uregs[RM_BITS(instr)];
793
794 if (IS_SHIFT(instr)) {
795 unsigned int shiftval = SHIFT_BITS(instr);
796
797 switch(SHIFT_TYPE(instr)) {
798 case SHIFT_LSL:
799 offset.un <<= shiftval;
800 break;
801
802 case SHIFT_LSR:
803 offset.un >>= shiftval;
804 break;
805
806 case SHIFT_ASR:
807 offset.sn >>= shiftval;
808 break;
809
810 case SHIFT_RORRRX:
811 if (shiftval == 0) {
812 offset.un >>= 1;
813 if (regs->ARM_cpsr & PSR_C_BIT)
814 offset.un |= 1 << 31;
815 } else
816 offset.un = offset.un >> shiftval |
817 offset.un << (32 - shiftval);
818 break;
819 }
820 }
821 handler = do_alignment_ldrstr;
822 break;
823
824 case 0x08000000: /* ldm or stm, or thumb-2 32bit instruction */
825 if (thumb2_32b)
826 handler = do_alignment_t32_to_handler(&instr, regs, &offset);
827 else
828 handler = do_alignment_ldmstm;
829 break;
830
831 default:
832 goto bad;
833 }
834
835 if (!handler)
836 goto bad;
837 type = handler(addr, instr, regs);
838
839 if (type == TYPE_ERROR || type == TYPE_FAULT) {
840 regs->ARM_pc -= isize;
841 goto bad_or_fault;
842 }
843
844 if (type == TYPE_LDST)
845 do_alignment_finish_ldst(addr, instr, regs, offset);
846
847 return 0;
848
849 bad_or_fault:
850 if (type == TYPE_ERROR)
851 goto bad;
852 /*
853 * We got a fault - fix it up, or die.
854 */
855 do_bad_area(addr, fsr, regs);
856 return 0;
857
858 swp:
859 printk(KERN_ERR "Alignment trap: not handling swp instruction\n");
860
861 bad:
862 /*
863 * Oops, we didn't handle the instruction.
864 */
865 printk(KERN_ERR "Alignment trap: not handling instruction "
866 "%0*lx at [<%08lx>]\n",
867 isize << 1,
868 isize == 2 ? tinstr : instr, instrptr);
869 ai_skipped += 1;
870 return 1;
871
872 user:
873 ai_user += 1;
874
875 if (ai_usermode & UM_WARN)
876 printk("Alignment trap: %s (%d) PC=0x%08lx Instr=0x%0*lx "
877 "Address=0x%08lx FSR 0x%03x\n", current->comm,
878 task_pid_nr(current), instrptr,
879 isize << 1,
880 isize == 2 ? tinstr : instr,
881 addr, fsr);
882
883 if (ai_usermode & UM_FIXUP)
884 goto fixup;
885
886 if (ai_usermode & UM_SIGNAL)
887 force_sig(SIGBUS, current);
888 else {
889 /*
890 * We're about to disable the alignment trap and return to
891 * user space. But if an interrupt occurs before actually
892 * reaching user space, then the IRQ vector entry code will
893 * notice that we were still in kernel space and therefore
894 * the alignment trap won't be re-enabled in that case as it
895 * is presumed to be always on from kernel space.
896 * Let's prevent that race by disabling interrupts here (they
897 * are disabled on the way back to user space anyway in
898 * entry-common.S) and disable the alignment trap only if
899 * there is no work pending for this thread.
900 */
901 raw_local_irq_disable();
902 if (!(current_thread_info()->flags & _TIF_WORK_MASK))
903 set_cr(cr_no_alignment);
904 }
905
906 return 0;
907 }
908
909 /*
910 * This needs to be done after sysctl_init, otherwise sys/ will be
911 * overwritten. Actually, this shouldn't be in sys/ at all since
912 * it isn't a sysctl, and it doesn't contain sysctl information.
913 * We now locate it in /proc/cpu/alignment instead.
914 */
915 static int __init alignment_init(void)
916 {
917 #ifdef CONFIG_PROC_FS
918 struct proc_dir_entry *res;
919
920 res = proc_create("cpu/alignment", S_IWUSR | S_IRUGO, NULL,
921 &alignment_proc_fops);
922 if (!res)
923 return -ENOMEM;
924 #endif
925
926 /*
927 * ARMv6 and later CPUs can perform unaligned accesses for
928 * most single load and store instructions up to word size.
929 * LDM, STM, LDRD and STRD still need to be handled.
930 *
931 * Ignoring the alignment fault is not an option on these
932 * CPUs since we spin re-faulting the instruction without
933 * making any progress.
934 */
935 if (cpu_architecture() >= CPU_ARCH_ARMv6 && (cr_alignment & CR_U)) {
936 cr_alignment &= ~CR_A;
937 cr_no_alignment &= ~CR_A;
938 set_cr(cr_alignment);
939 ai_usermode = UM_FIXUP;
940 }
941
942 hook_fault_code(1, do_alignment, SIGBUS, BUS_ADRALN,
943 "alignment exception");
944
945 /*
946 * ARMv6K and ARMv7 use fault status 3 (0b00011) as Access Flag section
947 * fault, not as alignment error.
948 *
949 * TODO: handle ARMv6K properly. Runtime check for 'K' extension is
950 * needed.
951 */
952 if (cpu_architecture() <= CPU_ARCH_ARMv6) {
953 hook_fault_code(3, do_alignment, SIGBUS, BUS_ADRALN,
954 "alignment exception");
955 }
956
957 return 0;
958 }
959
960 fs_initcall(alignment_init);
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