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First Support on Ginger and OMAP TI
[linux-ginger.git] / arch / arm / mm / alignment.c
blobb270d6228fe26ab7dea9a8e4d4c1f1bdeb804667
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/compiler.h>
15 #include <linux/kernel.h>
16 #include <linux/errno.h>
17 #include <linux/string.h>
18 #include <linux/proc_fs.h>
19 #include <linux/init.h>
20 #include <linux/sched.h>
21 #include <linux/uaccess.h>
22
23 #include <asm/unaligned.h>
24
25 #include "fault.h"
26
27 /*
28 * 32-bit misaligned trap handler (c) 1998 San Mehat (CCC) -July 1998
29 * /proc/sys/debug/alignment, modified and integrated into
30 * Linux 2.1 by Russell King
31 *
32 * Speed optimisations and better fault handling by Russell King.
33 *
34 * *** NOTE ***
35 * This code is not portable to processors with late data abort handling.
36 */
37 #define CODING_BITS(i) (i & 0x0e000000)
38
39 #define LDST_I_BIT(i) (i & (1 << 26)) /* Immediate constant */
40 #define LDST_P_BIT(i) (i & (1 << 24)) /* Preindex */
41 #define LDST_U_BIT(i) (i & (1 << 23)) /* Add offset */
42 #define LDST_W_BIT(i) (i & (1 << 21)) /* Writeback */
43 #define LDST_L_BIT(i) (i & (1 << 20)) /* Load */
44
45 #define LDST_P_EQ_U(i) ((((i) ^ ((i) >> 1)) & (1 << 23)) == 0)
46
47 #define LDSTHD_I_BIT(i) (i & (1 << 22)) /* double/half-word immed */
48 #define LDM_S_BIT(i) (i & (1 << 22)) /* write CPSR from SPSR */
49
50 #define RN_BITS(i) ((i >> 16) & 15) /* Rn */
51 #define RD_BITS(i) ((i >> 12) & 15) /* Rd */
52 #define RM_BITS(i) (i & 15) /* Rm */
53
54 #define REGMASK_BITS(i) (i & 0xffff)
55 #define OFFSET_BITS(i) (i & 0x0fff)
56
57 #define IS_SHIFT(i) (i & 0x0ff0)
58 #define SHIFT_BITS(i) ((i >> 7) & 0x1f)
59 #define SHIFT_TYPE(i) (i & 0x60)
60 #define SHIFT_LSL 0x00
61 #define SHIFT_LSR 0x20
62 #define SHIFT_ASR 0x40
63 #define SHIFT_RORRRX 0x60
64
65 #define BAD_INSTR 0xdeadc0de
66
67 /* Thumb-2 32 bit format per ARMv7 DDI0406A A6.3, either f800h,e800h,f800h */
68 #define IS_T32(hi16) \
69 (((hi16) & 0xe000) == 0xe000 && ((hi16) & 0x1800))
70
71 static unsigned long ai_user;
72 static unsigned long ai_sys;
73 static unsigned long ai_skipped;
74 static unsigned long ai_half;
75 static unsigned long ai_word;
76 static unsigned long ai_dword;
77 static unsigned long ai_multi;
78 static int ai_usermode;
79
80 #define UM_WARN (1 << 0)
81 #define UM_FIXUP (1 << 1)
82 #define UM_SIGNAL (1 << 2)
83
84 #ifdef CONFIG_PROC_FS
85 static const char *usermode_action[] = {
86 "ignored",
87 "warn",
88 "fixup",
89 "fixup+warn",
90 "signal",
91 "signal+warn"
92 };
93
94 static int
95 proc_alignment_read(char *page, char **start, off_t off, int count, int *eof,
96 void *data)
97 {
98 char *p = page;
99 int len;
100
101 p += sprintf(p, "User:\t\t%lu\n", ai_user);
102 p += sprintf(p, "System:\t\t%lu\n", ai_sys);
103 p += sprintf(p, "Skipped:\t%lu\n", ai_skipped);
104 p += sprintf(p, "Half:\t\t%lu\n", ai_half);
105 p += sprintf(p, "Word:\t\t%lu\n", ai_word);
106 if (cpu_architecture() >= CPU_ARCH_ARMv5TE)
107 p += sprintf(p, "DWord:\t\t%lu\n", ai_dword);
108 p += sprintf(p, "Multi:\t\t%lu\n", ai_multi);
109 p += sprintf(p, "User faults:\t%i (%s)\n", ai_usermode,
110 usermode_action[ai_usermode]);
111
112 len = (p - page) - off;
113 if (len < 0)
114 len = 0;
115
116 *eof = (len <= count) ? 1 : 0;
117 *start = page + off;
118
119 return len;
120 }
121
122 static int proc_alignment_write(struct file *file, const char __user *buffer,
123 unsigned long count, void *data)
124 {
125 char mode;
126
127 if (count > 0) {
128 if (get_user(mode, buffer))
129 return -EFAULT;
130 if (mode >= '0' && mode <= '5')
131 ai_usermode = mode - '0';
132 }
133 return count;
134 }
135
136 #endif /* CONFIG_PROC_FS */
137
138 union offset_union {
139 unsigned long un;
140 signed long sn;
141 };
142
143 #define TYPE_ERROR 0
144 #define TYPE_FAULT 1
145 #define TYPE_LDST 2
146 #define TYPE_DONE 3
147
148 #ifdef __ARMEB__
149 #define BE 1
150 #define FIRST_BYTE_16 "mov %1, %1, ror #8\n"
151 #define FIRST_BYTE_32 "mov %1, %1, ror #24\n"
152 #define NEXT_BYTE "ror #24"
153 #else
154 #define BE 0
155 #define FIRST_BYTE_16
156 #define FIRST_BYTE_32
157 #define NEXT_BYTE "lsr #8"
158 #endif
159
160 #define __get8_unaligned_check(ins,val,addr,err) \
161 __asm__( \
162 ARM( "1: "ins" %1, [%2], #1\n" ) \
163 THUMB( "1: "ins" %1, [%2]\n" ) \
164 THUMB( " add %2, %2, #1\n" ) \
165 "2:\n" \
166 " .section .fixup,\"ax\"\n" \
167 " .align 2\n" \
168 "3: mov %0, #1\n" \
169 " b 2b\n" \
170 " .previous\n" \
171 " .section __ex_table,\"a\"\n" \
172 " .align 3\n" \
173 " .long 1b, 3b\n" \
174 " .previous\n" \
175 : "=r" (err), "=&r" (val), "=r" (addr) \
176 : "0" (err), "2" (addr))
177
178 #define __get16_unaligned_check(ins,val,addr) \
179 do { \
180 unsigned int err = 0, v, a = addr; \
181 __get8_unaligned_check(ins,v,a,err); \
182 val = v << ((BE) ? 8 : 0); \
183 __get8_unaligned_check(ins,v,a,err); \
184 val |= v << ((BE) ? 0 : 8); \
185 if (err) \
186 goto fault; \
187 } while (0)
188
189 #define get16_unaligned_check(val,addr) \
190 __get16_unaligned_check("ldrb",val,addr)
191
192 #define get16t_unaligned_check(val,addr) \
193 __get16_unaligned_check("ldrbt",val,addr)
194
195 #define __get32_unaligned_check(ins,val,addr) \
196 do { \
197 unsigned int err = 0, v, a = addr; \
198 __get8_unaligned_check(ins,v,a,err); \
199 val = v << ((BE) ? 24 : 0); \
200 __get8_unaligned_check(ins,v,a,err); \
201 val |= v << ((BE) ? 16 : 8); \
202 __get8_unaligned_check(ins,v,a,err); \
203 val |= v << ((BE) ? 8 : 16); \
204 __get8_unaligned_check(ins,v,a,err); \
205 val |= v << ((BE) ? 0 : 24); \
206 if (err) \
207 goto fault; \
208 } while (0)
209
210 #define get32_unaligned_check(val,addr) \
211 __get32_unaligned_check("ldrb",val,addr)
212
213 #define get32t_unaligned_check(val,addr) \
214 __get32_unaligned_check("ldrbt",val,addr)
215
216 #define __put16_unaligned_check(ins,val,addr) \
217 do { \
218 unsigned int err = 0, v = val, a = addr; \
219 __asm__( FIRST_BYTE_16 \
220 ARM( "1: "ins" %1, [%2], #1\n" ) \
221 THUMB( "1: "ins" %1, [%2]\n" ) \
222 THUMB( " add %2, %2, #1\n" ) \
223 " mov %1, %1, "NEXT_BYTE"\n" \
224 "2: "ins" %1, [%2]\n" \
225 "3:\n" \
226 " .section .fixup,\"ax\"\n" \
227 " .align 2\n" \
228 "4: mov %0, #1\n" \
229 " b 3b\n" \
230 " .previous\n" \
231 " .section __ex_table,\"a\"\n" \
232 " .align 3\n" \
233 " .long 1b, 4b\n" \
234 " .long 2b, 4b\n" \
235 " .previous\n" \
236 : "=r" (err), "=&r" (v), "=&r" (a) \
237 : "0" (err), "1" (v), "2" (a)); \
238 if (err) \
239 goto fault; \
240 } while (0)
241
242 #define put16_unaligned_check(val,addr) \
243 __put16_unaligned_check("strb",val,addr)
244
245 #define put16t_unaligned_check(val,addr) \
246 __put16_unaligned_check("strbt",val,addr)
247
248 #define __put32_unaligned_check(ins,val,addr) \
249 do { \
250 unsigned int err = 0, v = val, a = addr; \
251 __asm__( FIRST_BYTE_32 \
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 ARM( "2: "ins" %1, [%2], #1\n" ) \
257 THUMB( "2: "ins" %1, [%2]\n" ) \
258 THUMB( " add %2, %2, #1\n" ) \
259 " mov %1, %1, "NEXT_BYTE"\n" \
260 ARM( "3: "ins" %1, [%2], #1\n" ) \
261 THUMB( "3: "ins" %1, [%2]\n" ) \
262 THUMB( " add %2, %2, #1\n" ) \
263 " mov %1, %1, "NEXT_BYTE"\n" \
264 "4: "ins" %1, [%2]\n" \
265 "5:\n" \
266 " .section .fixup,\"ax\"\n" \
267 " .align 2\n" \
268 "6: mov %0, #1\n" \
269 " b 5b\n" \
270 " .previous\n" \
271 " .section __ex_table,\"a\"\n" \
272 " .align 3\n" \
273 " .long 1b, 6b\n" \
274 " .long 2b, 6b\n" \
275 " .long 3b, 6b\n" \
276 " .long 4b, 6b\n" \
277 " .previous\n" \
278 : "=r" (err), "=&r" (v), "=&r" (a) \
279 : "0" (err), "1" (v), "2" (a)); \
280 if (err) \
281 goto fault; \
282 } while (0)
283
284 #define put32_unaligned_check(val,addr) \
285 __put32_unaligned_check("strb", val, addr)
286
287 #define put32t_unaligned_check(val,addr) \
288 __put32_unaligned_check("strbt", val, addr)
289
290 static void
291 do_alignment_finish_ldst(unsigned long addr, unsigned long instr, struct pt_regs *regs, union offset_union offset)
292 {
293 if (!LDST_U_BIT(instr))
294 offset.un = -offset.un;
295
296 if (!LDST_P_BIT(instr))
297 addr += offset.un;
298
299 if (!LDST_P_BIT(instr) || LDST_W_BIT(instr))
300 regs->uregs[RN_BITS(instr)] = addr;
301 }
302
303 static int
304 do_alignment_ldrhstrh(unsigned long addr, unsigned long instr, struct pt_regs *regs)
305 {
306 unsigned int rd = RD_BITS(instr);
307
308 ai_half += 1;
309
310 if (user_mode(regs))
311 goto user;
312
313 if (LDST_L_BIT(instr)) {
314 unsigned long val;
315 get16_unaligned_check(val, addr);
316
317 /* signed half-word? */
318 if (instr & 0x40)
319 val = (signed long)((signed short) val);
320
321 regs->uregs[rd] = val;
322 } else
323 put16_unaligned_check(regs->uregs[rd], addr);
324
325 return TYPE_LDST;
326
327 user:
328 if (LDST_L_BIT(instr)) {
329 unsigned long val;
330 get16t_unaligned_check(val, addr);
331
332 /* signed half-word? */
333 if (instr & 0x40)
334 val = (signed long)((signed short) val);
335
336 regs->uregs[rd] = val;
337 } else
338 put16t_unaligned_check(regs->uregs[rd], addr);
339
340 return TYPE_LDST;
341
342 fault:
343 return TYPE_FAULT;
344 }
345
346 static int
347 do_alignment_ldrdstrd(unsigned long addr, unsigned long instr,
348 struct pt_regs *regs)
349 {
350 unsigned int rd = RD_BITS(instr);
351 unsigned int rd2;
352 int load;
353
354 if ((instr & 0xfe000000) == 0xe8000000) {
355 /* ARMv7 Thumb-2 32-bit LDRD/STRD */
356 rd2 = (instr >> 8) & 0xf;
357 load = !!(LDST_L_BIT(instr));
358 } else if (((rd & 1) == 1) || (rd == 14))
359 goto bad;
360 else {
361 load = ((instr & 0xf0) == 0xd0);
362 rd2 = rd + 1;
363 }
364
365 ai_dword += 1;
366
367 if (user_mode(regs))
368 goto user;
369
370 if (load) {
371 unsigned long val;
372 get32_unaligned_check(val, addr);
373 regs->uregs[rd] = val;
374 get32_unaligned_check(val, addr + 4);
375 regs->uregs[rd2] = val;
376 } else {
377 put32_unaligned_check(regs->uregs[rd], addr);
378 put32_unaligned_check(regs->uregs[rd2], addr + 4);
379 }
380
381 return TYPE_LDST;
382
383 user:
384 if (load) {
385 unsigned long val;
386 get32t_unaligned_check(val, addr);
387 regs->uregs[rd] = val;
388 get32t_unaligned_check(val, addr + 4);
389 regs->uregs[rd2] = val;
390 } else {
391 put32t_unaligned_check(regs->uregs[rd], addr);
392 put32t_unaligned_check(regs->uregs[rd2], addr + 4);
393 }
394
395 return TYPE_LDST;
396 bad:
397 return TYPE_ERROR;
398 fault:
399 return TYPE_FAULT;
400 }
401
402 static int
403 do_alignment_ldrstr(unsigned long addr, unsigned long instr, struct pt_regs *regs)
404 {
405 unsigned int rd = RD_BITS(instr);
406
407 ai_word += 1;
408
409 if ((!LDST_P_BIT(instr) && LDST_W_BIT(instr)) || user_mode(regs))
410 goto trans;
411
412 if (LDST_L_BIT(instr)) {
413 unsigned int val;
414 get32_unaligned_check(val, addr);
415 regs->uregs[rd] = val;
416 } else
417 put32_unaligned_check(regs->uregs[rd], addr);
418 return TYPE_LDST;
419
420 trans:
421 if (LDST_L_BIT(instr)) {
422 unsigned int val;
423 get32t_unaligned_check(val, addr);
424 regs->uregs[rd] = val;
425 } else
426 put32t_unaligned_check(regs->uregs[rd], addr);
427 return TYPE_LDST;
428
429 fault:
430 return TYPE_FAULT;
431 }
432
433 /*
434 * LDM/STM alignment handler.
435 *
436 * There are 4 variants of this instruction:
437 *
438 * B = rn pointer before instruction, A = rn pointer after instruction
439 * ------ increasing address ----->
440 * | | r0 | r1 | ... | rx | |
441 * PU = 01 B A
442 * PU = 11 B A
443 * PU = 00 A B
444 * PU = 10 A B
445 */
446 static int
447 do_alignment_ldmstm(unsigned long addr, unsigned long instr, struct pt_regs *regs)
448 {
449 unsigned int rd, rn, correction, nr_regs, regbits;
450 unsigned long eaddr, newaddr;
451
452 if (LDM_S_BIT(instr))
453 goto bad;
454
455 correction = 4; /* processor implementation defined */
456 regs->ARM_pc += correction;
457
458 ai_multi += 1;
459
460 /* count the number of registers in the mask to be transferred */
461 nr_regs = hweight16(REGMASK_BITS(instr)) * 4;
462
463 rn = RN_BITS(instr);
464 newaddr = eaddr = regs->uregs[rn];
465
466 if (!LDST_U_BIT(instr))
467 nr_regs = -nr_regs;
468 newaddr += nr_regs;
469 if (!LDST_U_BIT(instr))
470 eaddr = newaddr;
471
472 if (LDST_P_EQ_U(instr)) /* U = P */
473 eaddr += 4;
474
475 /*
476 * For alignment faults on the ARM922T/ARM920T the MMU makes
477 * the FSR (and hence addr) equal to the updated base address
478 * of the multiple access rather than the restored value.
479 * Switch this message off if we've got a ARM92[02], otherwise
480 * [ls]dm alignment faults are noisy!
481 */
482 #if !(defined CONFIG_CPU_ARM922T) && !(defined CONFIG_CPU_ARM920T)
483 /*
484 * This is a "hint" - we already have eaddr worked out by the
485 * processor for us.
486 */
487 if (addr != eaddr) {
488 printk(KERN_ERR "LDMSTM: PC = %08lx, instr = %08lx, "
489 "addr = %08lx, eaddr = %08lx\n",
490 instruction_pointer(regs), instr, addr, eaddr);
491 show_regs(regs);
492 }
493 #endif
494
495 if (user_mode(regs)) {
496 for (regbits = REGMASK_BITS(instr), rd = 0; regbits;
497 regbits >>= 1, rd += 1)
498 if (regbits & 1) {
499 if (LDST_L_BIT(instr)) {
500 unsigned int val;
501 get32t_unaligned_check(val, eaddr);
502 regs->uregs[rd] = val;
503 } else
504 put32t_unaligned_check(regs->uregs[rd], eaddr);
505 eaddr += 4;
506 }
507 } else {
508 for (regbits = REGMASK_BITS(instr), rd = 0; regbits;
509 regbits >>= 1, rd += 1)
510 if (regbits & 1) {
511 if (LDST_L_BIT(instr)) {
512 unsigned int val;
513 get32_unaligned_check(val, eaddr);
514 regs->uregs[rd] = val;
515 } else
516 put32_unaligned_check(regs->uregs[rd], eaddr);
517 eaddr += 4;
518 }
519 }
520
521 if (LDST_W_BIT(instr))
522 regs->uregs[rn] = newaddr;
523 if (!LDST_L_BIT(instr) || !(REGMASK_BITS(instr) & (1 << 15)))
524 regs->ARM_pc -= correction;
525 return TYPE_DONE;
526
527 fault:
528 regs->ARM_pc -= correction;
529 return TYPE_FAULT;
530
531 bad:
532 printk(KERN_ERR "Alignment trap: not handling ldm with s-bit set\n");
533 return TYPE_ERROR;
534 }
535
536 /*
537 * Convert Thumb ld/st instruction forms to equivalent ARM instructions so
538 * we can reuse ARM userland alignment fault fixups for Thumb.
539 *
540 * This implementation was initially based on the algorithm found in
541 * gdb/sim/arm/thumbemu.c. It is basically just a code reduction of same
542 * to convert only Thumb ld/st instruction forms to equivalent ARM forms.
543 *
544 * NOTES:
545 * 1. Comments below refer to ARM ARM DDI0100E Thumb Instruction sections.
546 * 2. If for some reason we're passed an non-ld/st Thumb instruction to
547 * decode, we return 0xdeadc0de. This should never happen under normal
548 * circumstances but if it does, we've got other problems to deal with
549 * elsewhere and we obviously can't fix those problems here.
550 */
551
552 static unsigned long
553 thumb2arm(u16 tinstr)
554 {
555 u32 L = (tinstr & (1<<11)) >> 11;
556
557 switch ((tinstr & 0xf800) >> 11) {
558 /* 6.5.1 Format 1: */
559 case 0x6000 >> 11: /* 7.1.52 STR(1) */
560 case 0x6800 >> 11: /* 7.1.26 LDR(1) */
561 case 0x7000 >> 11: /* 7.1.55 STRB(1) */
562 case 0x7800 >> 11: /* 7.1.30 LDRB(1) */
563 return 0xe5800000 |
564 ((tinstr & (1<<12)) << (22-12)) | /* fixup */
565 (L<<20) | /* L==1? */
566 ((tinstr & (7<<0)) << (12-0)) | /* Rd */
567 ((tinstr & (7<<3)) << (16-3)) | /* Rn */
568 ((tinstr & (31<<6)) >> /* immed_5 */
569 (6 - ((tinstr & (1<<12)) ? 0 : 2)));
570 case 0x8000 >> 11: /* 7.1.57 STRH(1) */
571 case 0x8800 >> 11: /* 7.1.32 LDRH(1) */
572 return 0xe1c000b0 |
573 (L<<20) | /* L==1? */
574 ((tinstr & (7<<0)) << (12-0)) | /* Rd */
575 ((tinstr & (7<<3)) << (16-3)) | /* Rn */
576 ((tinstr & (7<<6)) >> (6-1)) | /* immed_5[2:0] */
577 ((tinstr & (3<<9)) >> (9-8)); /* immed_5[4:3] */
578
579 /* 6.5.1 Format 2: */
580 case 0x5000 >> 11:
581 case 0x5800 >> 11:
582 {
583 static const u32 subset[8] = {
584 0xe7800000, /* 7.1.53 STR(2) */
585 0xe18000b0, /* 7.1.58 STRH(2) */
586 0xe7c00000, /* 7.1.56 STRB(2) */
587 0xe19000d0, /* 7.1.34 LDRSB */
588 0xe7900000, /* 7.1.27 LDR(2) */
589 0xe19000b0, /* 7.1.33 LDRH(2) */
590 0xe7d00000, /* 7.1.31 LDRB(2) */
591 0xe19000f0 /* 7.1.35 LDRSH */
592 };
593 return subset[(tinstr & (7<<9)) >> 9] |
594 ((tinstr & (7<<0)) << (12-0)) | /* Rd */
595 ((tinstr & (7<<3)) << (16-3)) | /* Rn */
596 ((tinstr & (7<<6)) >> (6-0)); /* Rm */
597 }
598
599 /* 6.5.1 Format 3: */
600 case 0x4800 >> 11: /* 7.1.28 LDR(3) */
601 /* NOTE: This case is not technically possible. We're
602 * loading 32-bit memory data via PC relative
603 * addressing mode. So we can and should eliminate
604 * this case. But I'll leave it here for now.
605 */
606 return 0xe59f0000 |
607 ((tinstr & (7<<8)) << (12-8)) | /* Rd */
608 ((tinstr & 255) << (2-0)); /* immed_8 */
609
610 /* 6.5.1 Format 4: */
611 case 0x9000 >> 11: /* 7.1.54 STR(3) */
612 case 0x9800 >> 11: /* 7.1.29 LDR(4) */
613 return 0xe58d0000 |
614 (L<<20) | /* L==1? */
615 ((tinstr & (7<<8)) << (12-8)) | /* Rd */
616 ((tinstr & 255) << 2); /* immed_8 */
617
618 /* 6.6.1 Format 1: */
619 case 0xc000 >> 11: /* 7.1.51 STMIA */
620 case 0xc800 >> 11: /* 7.1.25 LDMIA */
621 {
622 u32 Rn = (tinstr & (7<<8)) >> 8;
623 u32 W = ((L<<Rn) & (tinstr&255)) ? 0 : 1<<21;
624
625 return 0xe8800000 | W | (L<<20) | (Rn<<16) |
626 (tinstr&255);
627 }
628
629 /* 6.6.1 Format 2: */
630 case 0xb000 >> 11: /* 7.1.48 PUSH */
631 case 0xb800 >> 11: /* 7.1.47 POP */
632 if ((tinstr & (3 << 9)) == 0x0400) {
633 static const u32 subset[4] = {
634 0xe92d0000, /* STMDB sp!,{registers} */
635 0xe92d4000, /* STMDB sp!,{registers,lr} */
636 0xe8bd0000, /* LDMIA sp!,{registers} */
637 0xe8bd8000 /* LDMIA sp!,{registers,pc} */
638 };
639 return subset[(L<<1) | ((tinstr & (1<<8)) >> 8)] |
640 (tinstr & 255); /* register_list */
641 }
642 /* Else fall through for illegal instruction case */
643
644 default:
645 return BAD_INSTR;
646 }
647 }
648
649 /*
650 * Convert Thumb-2 32 bit LDM, STM, LDRD, STRD to equivalent instruction
651 * handlable by ARM alignment handler, also find the corresponding handler,
652 * so that we can reuse ARM userland alignment fault fixups for Thumb.
653 *
654 * @pinstr: original Thumb-2 instruction; returns new handlable instruction
655 * @regs: register context.
656 * @poffset: return offset from faulted addr for later writeback
657 *
658 * NOTES:
659 * 1. Comments below refer to ARMv7 DDI0406A Thumb Instruction sections.
660 * 2. Register name Rt from ARMv7 is same as Rd from ARMv6 (Rd is Rt)
661 */
662 static void *
663 do_alignment_t32_to_handler(unsigned long *pinstr, struct pt_regs *regs,
664 union offset_union *poffset)
665 {
666 unsigned long instr = *pinstr;
667 u16 tinst1 = (instr >> 16) & 0xffff;
668 u16 tinst2 = instr & 0xffff;
669 poffset->un = 0;
670
671 switch (tinst1 & 0xffe0) {
672 /* A6.3.5 Load/Store multiple */
673 case 0xe880: /* STM/STMIA/STMEA,LDM/LDMIA, PUSH/POP T2 */
674 case 0xe8a0: /* ...above writeback version */
675 case 0xe900: /* STMDB/STMFD, LDMDB/LDMEA */
676 case 0xe920: /* ...above writeback version */
677 /* no need offset decision since handler calculates it */
678 return do_alignment_ldmstm;
679
680 case 0xf840: /* POP/PUSH T3 (single register) */
681 if (RN_BITS(instr) == 13 && (tinst2 & 0x09ff) == 0x0904) {
682 u32 L = !!(LDST_L_BIT(instr));
683 const u32 subset[2] = {
684 0xe92d0000, /* STMDB sp!,{registers} */
685 0xe8bd0000, /* LDMIA sp!,{registers} */
686 };
687 *pinstr = subset[L] | (1<<RD_BITS(instr));
688 return do_alignment_ldmstm;
689 }
690 /* Else fall through for illegal instruction case */
691 break;
692
693 /* A6.3.6 Load/store double, STRD/LDRD(immed, lit, reg) */
694 case 0xe860:
695 case 0xe960:
696 case 0xe8e0:
697 case 0xe9e0:
698 poffset->un = (tinst2 & 0xff) << 2;
699 case 0xe940:
700 case 0xe9c0:
701 return do_alignment_ldrdstrd;
702
703 /*
704 * No need to handle load/store instructions up to word size
705 * since ARMv6 and later CPUs can perform unaligned accesses.
706 */
707 default:
708 break;
709 }
710 return NULL;
711 }
712
713 static int
714 do_alignment(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
715 {
716 union offset_union offset;
717 unsigned long instr = 0, instrptr;
718 int (*handler)(unsigned long addr, unsigned long instr, struct pt_regs *regs);
719 unsigned int type;
720 mm_segment_t fs;
721 unsigned int fault;
722 u16 tinstr = 0;
723 int isize = 4;
724 int thumb2_32b = 0;
725
726 instrptr = instruction_pointer(regs);
727
728 fs = get_fs();
729 set_fs(KERNEL_DS);
730 if (thumb_mode(regs)) {
731 fault = __get_user(tinstr, (u16 *)(instrptr & ~1));
732 if (!fault) {
733 if (cpu_architecture() >= CPU_ARCH_ARMv7 &&
734 IS_T32(tinstr)) {
735 /* Thumb-2 32-bit */
736 u16 tinst2 = 0;
737 fault = __get_user(tinst2, (u16 *)(instrptr+2));
738 instr = (tinstr << 16) | tinst2;
739 thumb2_32b = 1;
740 } else {
741 isize = 2;
742 instr = thumb2arm(tinstr);
743 }
744 }
745 } else
746 fault = __get_user(instr, (u32 *)instrptr);
747 set_fs(fs);
748
749 if (fault) {
750 type = TYPE_FAULT;
751 goto bad_or_fault;
752 }
753
754 if (user_mode(regs))
755 goto user;
756
757 ai_sys += 1;
758
759 fixup:
760
761 regs->ARM_pc += isize;
762
763 switch (CODING_BITS(instr)) {
764 case 0x00000000: /* 3.13.4 load/store instruction extensions */
765 if (LDSTHD_I_BIT(instr))
766 offset.un = (instr & 0xf00) >> 4 | (instr & 15);
767 else
768 offset.un = regs->uregs[RM_BITS(instr)];
769
770 if ((instr & 0x000000f0) == 0x000000b0 || /* LDRH, STRH */
771 (instr & 0x001000f0) == 0x001000f0) /* LDRSH */
772 handler = do_alignment_ldrhstrh;
773 else if ((instr & 0x001000f0) == 0x000000d0 || /* LDRD */
774 (instr & 0x001000f0) == 0x000000f0) /* STRD */
775 handler = do_alignment_ldrdstrd;
776 else if ((instr & 0x01f00ff0) == 0x01000090) /* SWP */
777 goto swp;
778 else
779 goto bad;
780 break;
781
782 case 0x04000000: /* ldr or str immediate */
783 offset.un = OFFSET_BITS(instr);
784 handler = do_alignment_ldrstr;
785 break;
786
787 case 0x06000000: /* ldr or str register */
788 offset.un = regs->uregs[RM_BITS(instr)];
789
790 if (IS_SHIFT(instr)) {
791 unsigned int shiftval = SHIFT_BITS(instr);
792
793 switch(SHIFT_TYPE(instr)) {
794 case SHIFT_LSL:
795 offset.un <<= shiftval;
796 break;
797
798 case SHIFT_LSR:
799 offset.un >>= shiftval;
800 break;
801
802 case SHIFT_ASR:
803 offset.sn >>= shiftval;
804 break;
805
806 case SHIFT_RORRRX:
807 if (shiftval == 0) {
808 offset.un >>= 1;
809 if (regs->ARM_cpsr & PSR_C_BIT)
810 offset.un |= 1 << 31;
811 } else
812 offset.un = offset.un >> shiftval |
813 offset.un << (32 - shiftval);
814 break;
815 }
816 }
817 handler = do_alignment_ldrstr;
818 break;
819
820 case 0x08000000: /* ldm or stm, or thumb-2 32bit instruction */
821 if (thumb2_32b)
822 handler = do_alignment_t32_to_handler(&instr, regs, &offset);
823 else
824 handler = do_alignment_ldmstm;
825 break;
826
827 default:
828 goto bad;
829 }
830
831 if (!handler)
832 goto bad;
833 type = handler(addr, instr, regs);
834
835 if (type == TYPE_ERROR || type == TYPE_FAULT) {
836 regs->ARM_pc -= isize;
837 goto bad_or_fault;
838 }
839
840 if (type == TYPE_LDST)
841 do_alignment_finish_ldst(addr, instr, regs, offset);
842
843 return 0;
844
845 bad_or_fault:
846 if (type == TYPE_ERROR)
847 goto bad;
848 /*
849 * We got a fault - fix it up, or die.
850 */
851 do_bad_area(addr, fsr, regs);
852 return 0;
853
854 swp:
855 printk(KERN_ERR "Alignment trap: not handling swp instruction\n");
856
857 bad:
858 /*
859 * Oops, we didn't handle the instruction.
860 */
861 printk(KERN_ERR "Alignment trap: not handling instruction "
862 "%0*lx at [<%08lx>]\n",
863 isize << 1,
864 isize == 2 ? tinstr : instr, instrptr);
865 ai_skipped += 1;
866 return 1;
867
868 user:
869 ai_user += 1;
870
871 if (ai_usermode & UM_WARN)
872 printk("Alignment trap: %s (%d) PC=0x%08lx Instr=0x%0*lx "
873 "Address=0x%08lx FSR 0x%03x\n", current->comm,
874 task_pid_nr(current), instrptr,
875 isize << 1,
876 isize == 2 ? tinstr : instr,
877 addr, fsr);
878
879 if (ai_usermode & UM_FIXUP)
880 goto fixup;
881
882 if (ai_usermode & UM_SIGNAL)
883 force_sig(SIGBUS, current);
884 else
885 set_cr(cr_no_alignment);
886
887 return 0;
888 }
889
890 /*
891 * This needs to be done after sysctl_init, otherwise sys/ will be
892 * overwritten. Actually, this shouldn't be in sys/ at all since
893 * it isn't a sysctl, and it doesn't contain sysctl information.
894 * We now locate it in /proc/cpu/alignment instead.
895 */
896 static int __init alignment_init(void)
897 {
898 #ifdef CONFIG_PROC_FS
899 struct proc_dir_entry *res;
900
901 res = proc_mkdir("cpu", NULL);
902 if (!res)
903 return -ENOMEM;
904
905 res = create_proc_entry("alignment", S_IWUSR | S_IRUGO, res);
906 if (!res)
907 return -ENOMEM;
908
909 res->read_proc = proc_alignment_read;
910 res->write_proc = proc_alignment_write;
911 #endif
912
913 /*
914 * ARMv6 and later CPUs can perform unaligned accesses for
915 * most single load and store instructions up to word size.
916 * LDM, STM, LDRD and STRD still need to be handled.
917 *
918 * Ignoring the alignment fault is not an option on these
919 * CPUs since we spin re-faulting the instruction without
920 * making any progress.
921 */
922 if (cpu_architecture() >= CPU_ARCH_ARMv6 && (cr_alignment & CR_U)) {
923 cr_alignment &= ~CR_A;
924 cr_no_alignment &= ~CR_A;
925 set_cr(cr_alignment);
926 ai_usermode = UM_FIXUP;
927 }
928
929 hook_fault_code(1, do_alignment, SIGILL, "alignment exception");
930 hook_fault_code(3, do_alignment, SIGILL, "alignment exception");
931
932 return 0;
933 }
934
935 fs_initcall(alignment_init);
Linux for Ginger Game Console