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ARM: 8321/1: asm-generic: introduce .text.fixup input section
[deliverable/linux.git] / arch / arm / mm / alignment.c
CommitLineData
1da177e4
LT		 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
6cbdc8c5 6 * Thumb alignment fault fixups (c) 2004 MontaVista Software, Inc.
1da177e4
LT		 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 */
d944d549 14#include <linux/moduleparam.h>
1da177e4
LT		 15#include <linux/compiler.h>
16#include <linux/kernel.h>
17#include <linux/errno.h>
18#include <linux/string.h>
1da177e4 19#include <linux/proc_fs.h>
b7072c63 20#include <linux/seq_file.h>
1da177e4 21#include <linux/init.h>
87c52578 22#include <linux/sched.h>
33fa9b13 23#include <linux/uaccess.h>
1da177e4 24
15d07dc9 25#include <asm/cp15.h>
9f97da78 26#include <asm/system_info.h>
1da177e4 27#include <asm/unaligned.h>
8592edf0 28#include <asm/opcodes.h>
1da177e4
LT		 29
30#include "fault.h"
b4b20ad8 31#include "mm.h"
1da177e4
LT		 32
33/*
34 * 32-bit misaligned trap handler (c) 1998 San Mehat (CCC) -July 1998
35 * /proc/sys/debug/alignment, modified and integrated into
36 * Linux 2.1 by Russell King
37 *
38 * Speed optimisations and better fault handling by Russell King.
39 *
40 * *** NOTE ***
41 * This code is not portable to processors with late data abort handling.
42 */
43#define CODING_BITS(i) (i & 0x0e000000)
5ca918e5 44#define COND_BITS(i) (i & 0xf0000000)
1da177e4
LT		 45
46#define LDST_I_BIT(i) (i & (1 << 26)) /* Immediate constant */
47#define LDST_P_BIT(i) (i & (1 << 24)) /* Preindex */
48#define LDST_U_BIT(i) (i & (1 << 23)) /* Add offset */
49#define LDST_W_BIT(i) (i & (1 << 21)) /* Writeback */
50#define LDST_L_BIT(i) (i & (1 << 20)) /* Load */
51
52#define LDST_P_EQ_U(i) ((((i) ^ ((i) >> 1)) & (1 << 23)) == 0)
53
f21ee2d4 54#define LDSTHD_I_BIT(i) (i & (1 << 22)) /* double/half-word immed */
1da177e4
LT		 55#define LDM_S_BIT(i) (i & (1 << 22)) /* write CPSR from SPSR */
56
57#define RN_BITS(i) ((i >> 16) & 15) /* Rn */
58#define RD_BITS(i) ((i >> 12) & 15) /* Rd */
59#define RM_BITS(i) (i & 15) /* Rm */
60
61#define REGMASK_BITS(i) (i & 0xffff)
62#define OFFSET_BITS(i) (i & 0x0fff)
63
64#define IS_SHIFT(i) (i & 0x0ff0)
65#define SHIFT_BITS(i) ((i >> 7) & 0x1f)
66#define SHIFT_TYPE(i) (i & 0x60)
67#define SHIFT_LSL 0x00
68#define SHIFT_LSR 0x20
69#define SHIFT_ASR 0x40
70#define SHIFT_RORRRX 0x60
71
c2860d43
GD		 72#define BAD_INSTR 0xdeadc0de
73
74/* Thumb-2 32 bit format per ARMv7 DDI0406A A6.3, either f800h,e800h,f800h */
75#define IS_T32(hi16) \
76 (((hi16) & 0xe000) == 0xe000 && ((hi16) & 0x1800))
77
1da177e4
LT		 78static unsigned long ai_user;
79static unsigned long ai_sys;
1e7e3211 80static void *ai_sys_last_pc;
1da177e4
LT		 81static unsigned long ai_skipped;
82static unsigned long ai_half;
83static unsigned long ai_word;
f21ee2d4 84static unsigned long ai_dword;
1da177e4
LT		 85static unsigned long ai_multi;
86static int ai_usermode;
0aeb3408 87static unsigned long cr_no_alignment;
1da177e4 88
d944d549
RK		 89core_param(alignment, ai_usermode, int, 0600);
90
baa745a3
RK		 91#define UM_WARN (1 << 0)
92#define UM_FIXUP (1 << 1)
93#define UM_SIGNAL (1 << 2)
94
088c01f1
DM		 95/* Return true if and only if the ARMv6 unaligned access model is in use. */
96static bool cpu_is_v6_unaligned(void)
97{
4585eaff 98 return cpu_architecture() >= CPU_ARCH_ARMv6 && get_cr() & CR_U;
088c01f1
DM		 99}
100
101static int safe_usermode(int new_usermode, bool warn)
102{
103 /*
104 * ARMv6 and later CPUs can perform unaligned accesses for
105 * most single load and store instructions up to word size.
106 * LDM, STM, LDRD and STRD still need to be handled.
107 *
108 * Ignoring the alignment fault is not an option on these
109 * CPUs since we spin re-faulting the instruction without
110 * making any progress.
111 */
112 if (cpu_is_v6_unaligned() && !(new_usermode & (UM_FIXUP | UM_SIGNAL))) {
113 new_usermode |= UM_FIXUP;
114
115 if (warn)
4ed89f22 116 pr_warn("alignment: ignoring faults is unsafe on this CPU. Defaulting to fixup mode.\n");
088c01f1
DM		 117 }
118
119 return new_usermode;
120}
121
ffc660c5
AB		 122#ifdef CONFIG_PROC_FS
123static const char *usermode_action[] = {
124 "ignored",
125 "warn",
126 "fixup",
127 "fixup+warn",
128 "signal",
129 "signal+warn"
130};
131
b7072c63 132static int alignment_proc_show(struct seq_file *m, void *v)
1da177e4 133{
b7072c63 134 seq_printf(m, "User:\t\t%lu\n", ai_user);
1e7e3211 135 seq_printf(m, "System:\t\t%lu (%pF)\n", ai_sys, ai_sys_last_pc);
b7072c63
AD		 136 seq_printf(m, "Skipped:\t%lu\n", ai_skipped);
137 seq_printf(m, "Half:\t\t%lu\n", ai_half);
138 seq_printf(m, "Word:\t\t%lu\n", ai_word);
f21ee2d4 139 if (cpu_architecture() >= CPU_ARCH_ARMv5TE)
b7072c63
AD		 140 seq_printf(m, "DWord:\t\t%lu\n", ai_dword);
141 seq_printf(m, "Multi:\t\t%lu\n", ai_multi);
142 seq_printf(m, "User faults:\t%i (%s)\n", ai_usermode,
1da177e4
LT		 143 usermode_action[ai_usermode]);
144
b7072c63
AD		 145 return 0;
146}
1da177e4 147
b7072c63
AD		 148static int alignment_proc_open(struct inode *inode, struct file *file)
149{
150 return single_open(file, alignment_proc_show, NULL);
1da177e4
LT		 151}
152
b7072c63
AD		 153static ssize_t alignment_proc_write(struct file *file, const char __user *buffer,
154 size_t count, loff_t *pos)
1da177e4
LT		 155{
156 char mode;
157
158 if (count > 0) {
159 if (get_user(mode, buffer))
160 return -EFAULT;
161 if (mode >= '0' && mode <= '5')
088c01f1 162 ai_usermode = safe_usermode(mode - '0', true);
1da177e4
LT		 163 }
164 return count;
165}
166
b7072c63
AD		 167static const struct file_operations alignment_proc_fops = {
168 .open = alignment_proc_open,
169 .read = seq_read,
170 .llseek = seq_lseek,
171 .release = single_release,
172 .write = alignment_proc_write,
173};
1da177e4
LT		 174#endif /* CONFIG_PROC_FS */
175
176union offset_union {
177 unsigned long un;
178 signed long sn;
179};
180
181#define TYPE_ERROR 0
182#define TYPE_FAULT 1
183#define TYPE_LDST 2
184#define TYPE_DONE 3
185
186#ifdef __ARMEB__
187#define BE 1
188#define FIRST_BYTE_16 "mov %1, %1, ror #8\n"
189#define FIRST_BYTE_32 "mov %1, %1, ror #24\n"
190#define NEXT_BYTE "ror #24"
191#else
192#define BE 0
193#define FIRST_BYTE_16
194#define FIRST_BYTE_32
195#define NEXT_BYTE "lsr #8"
196#endif
197
198#define __get8_unaligned_check(ins,val,addr,err) \
199 __asm__( \
347c8b70
CM		 200 ARM( "1: "ins" %1, [%2], #1\n" ) \
201 THUMB( "1: "ins" %1, [%2]\n" ) \
202 THUMB( " add %2, %2, #1\n" ) \
1da177e4 203 "2:\n" \
4260415f 204 " .pushsection .fixup,\"ax\"\n" \
1da177e4
LT		 205 " .align 2\n" \
206 "3: mov %0, #1\n" \
207 " b 2b\n" \
4260415f
RK		 208 " .popsection\n" \
209 " .pushsection __ex_table,\"a\"\n" \
1da177e4
LT		 210 " .align 3\n" \
211 " .long 1b, 3b\n" \
4260415f 212 " .popsection\n" \
1da177e4
LT		 213 : "=r" (err), "=&r" (val), "=r" (addr) \
214 : "0" (err), "2" (addr))
215
216#define __get16_unaligned_check(ins,val,addr) \
217 do { \
218 unsigned int err = 0, v, a = addr; \
219 __get8_unaligned_check(ins,v,a,err); \
220 val = v << ((BE) ? 8 : 0); \
221 __get8_unaligned_check(ins,v,a,err); \
222 val |= v << ((BE) ? 0 : 8); \
223 if (err) \
224 goto fault; \
225 } while (0)
226
227#define get16_unaligned_check(val,addr) \
228 __get16_unaligned_check("ldrb",val,addr)
229
230#define get16t_unaligned_check(val,addr) \
231 __get16_unaligned_check("ldrbt",val,addr)
232
233#define __get32_unaligned_check(ins,val,addr) \
234 do { \
235 unsigned int err = 0, v, a = addr; \
236 __get8_unaligned_check(ins,v,a,err); \
237 val = v << ((BE) ? 24 : 0); \
238 __get8_unaligned_check(ins,v,a,err); \
239 val |= v << ((BE) ? 16 : 8); \
240 __get8_unaligned_check(ins,v,a,err); \
241 val |= v << ((BE) ? 8 : 16); \
242 __get8_unaligned_check(ins,v,a,err); \
243 val |= v << ((BE) ? 0 : 24); \
244 if (err) \
245 goto fault; \
246 } while (0)
247
248#define get32_unaligned_check(val,addr) \
249 __get32_unaligned_check("ldrb",val,addr)
250
251#define get32t_unaligned_check(val,addr) \
252 __get32_unaligned_check("ldrbt",val,addr)
253
254#define __put16_unaligned_check(ins,val,addr) \
255 do { \
256 unsigned int err = 0, v = val, a = addr; \
257 __asm__( FIRST_BYTE_16 \
347c8b70
CM		 258 ARM( "1: "ins" %1, [%2], #1\n" ) \
259 THUMB( "1: "ins" %1, [%2]\n" ) \
260 THUMB( " add %2, %2, #1\n" ) \
1da177e4
LT		 261 " mov %1, %1, "NEXT_BYTE"\n" \
262 "2: "ins" %1, [%2]\n" \
263 "3:\n" \
4260415f 264 " .pushsection .fixup,\"ax\"\n" \
1da177e4
LT		 265 " .align 2\n" \
266 "4: mov %0, #1\n" \
267 " b 3b\n" \
4260415f
RK		 268 " .popsection\n" \
269 " .pushsection __ex_table,\"a\"\n" \
1da177e4
LT		 270 " .align 3\n" \
271 " .long 1b, 4b\n" \
272 " .long 2b, 4b\n" \
4260415f 273 " .popsection\n" \
1da177e4
LT		 274 : "=r" (err), "=&r" (v), "=&r" (a) \
275 : "0" (err), "1" (v), "2" (a)); \
276 if (err) \
277 goto fault; \
278 } while (0)
279
280#define put16_unaligned_check(val,addr) \
281 __put16_unaligned_check("strb",val,addr)
282
283#define put16t_unaligned_check(val,addr) \
284 __put16_unaligned_check("strbt",val,addr)
285
286#define __put32_unaligned_check(ins,val,addr) \
287 do { \
288 unsigned int err = 0, v = val, a = addr; \
289 __asm__( FIRST_BYTE_32 \
347c8b70
CM		 290 ARM( "1: "ins" %1, [%2], #1\n" ) \
291 THUMB( "1: "ins" %1, [%2]\n" ) \
292 THUMB( " add %2, %2, #1\n" ) \
1da177e4 293 " mov %1, %1, "NEXT_BYTE"\n" \
347c8b70
CM		 294 ARM( "2: "ins" %1, [%2], #1\n" ) \
295 THUMB( "2: "ins" %1, [%2]\n" ) \
296 THUMB( " add %2, %2, #1\n" ) \
1da177e4 297 " mov %1, %1, "NEXT_BYTE"\n" \
347c8b70
CM		 298 ARM( "3: "ins" %1, [%2], #1\n" ) \
299 THUMB( "3: "ins" %1, [%2]\n" ) \
300 THUMB( " add %2, %2, #1\n" ) \
1da177e4
LT		 301 " mov %1, %1, "NEXT_BYTE"\n" \
302 "4: "ins" %1, [%2]\n" \
303 "5:\n" \
4260415f 304 " .pushsection .fixup,\"ax\"\n" \
1da177e4
LT		 305 " .align 2\n" \
306 "6: mov %0, #1\n" \
307 " b 5b\n" \
4260415f
RK		 308 " .popsection\n" \
309 " .pushsection __ex_table,\"a\"\n" \
1da177e4
LT		 310 " .align 3\n" \
311 " .long 1b, 6b\n" \
312 " .long 2b, 6b\n" \
313 " .long 3b, 6b\n" \
314 " .long 4b, 6b\n" \
4260415f 315 " .popsection\n" \
1da177e4
LT		 316 : "=r" (err), "=&r" (v), "=&r" (a) \
317 : "0" (err), "1" (v), "2" (a)); \
318 if (err) \
319 goto fault; \
320 } while (0)
321
737d0bb7 322#define put32_unaligned_check(val,addr) \
1da177e4
LT		 323 __put32_unaligned_check("strb", val, addr)
324
325#define put32t_unaligned_check(val,addr) \
326 __put32_unaligned_check("strbt", val, addr)
327
328static void
329do_alignment_finish_ldst(unsigned long addr, unsigned long instr, struct pt_regs *regs, union offset_union offset)
330{
331 if (!LDST_U_BIT(instr))
332 offset.un = -offset.un;
333
334 if (!LDST_P_BIT(instr))
335 addr += offset.un;
336
337 if (!LDST_P_BIT(instr) || LDST_W_BIT(instr))
338 regs->uregs[RN_BITS(instr)] = addr;
339}
340
341static int
342do_alignment_ldrhstrh(unsigned long addr, unsigned long instr, struct pt_regs *regs)
343{
344 unsigned int rd = RD_BITS(instr);
345
1da177e4
LT		 346 ai_half += 1;
347
348 if (user_mode(regs))
349 goto user;
350
351 if (LDST_L_BIT(instr)) {
352 unsigned long val;
353 get16_unaligned_check(val, addr);
354
355 /* signed half-word? */
356 if (instr & 0x40)
357 val = (signed long)((signed short) val);
358
359 regs->uregs[rd] = val;
360 } else
361 put16_unaligned_check(regs->uregs[rd], addr);
362
363 return TYPE_LDST;
364
365 user:
737d0bb7
GD		 366 if (LDST_L_BIT(instr)) {
367 unsigned long val;
368 get16t_unaligned_check(val, addr);
1da177e4 369
737d0bb7
GD		 370 /* signed half-word? */
371 if (instr & 0x40)
372 val = (signed long)((signed short) val);
1da177e4 373
737d0bb7
GD		 374 regs->uregs[rd] = val;
375 } else
376 put16t_unaligned_check(regs->uregs[rd], addr);
1da177e4 377
737d0bb7 378 return TYPE_LDST;
1da177e4 379
f21ee2d4
SL		 380 fault:
381 return TYPE_FAULT;
382}
383
384static int
385do_alignment_ldrdstrd(unsigned long addr, unsigned long instr,
386 struct pt_regs *regs)
387{
388 unsigned int rd = RD_BITS(instr);
c2860d43
GD		 389 unsigned int rd2;
390 int load;
391
392 if ((instr & 0xfe000000) == 0xe8000000) {
393 /* ARMv7 Thumb-2 32-bit LDRD/STRD */
394 rd2 = (instr >> 8) & 0xf;
395 load = !!(LDST_L_BIT(instr));
396 } else if (((rd & 1) == 1) || (rd == 14))
19da83f6 397 goto bad;
c2860d43
GD		 398 else {
399 load = ((instr & 0xf0) == 0xd0);
400 rd2 = rd + 1;
401 }
19da83f6 402
f21ee2d4
SL		 403 ai_dword += 1;
404
405 if (user_mode(regs))
406 goto user;
407
c2860d43 408 if (load) {
f21ee2d4
SL		 409 unsigned long val;
410 get32_unaligned_check(val, addr);
411 regs->uregs[rd] = val;
737d0bb7 412 get32_unaligned_check(val, addr + 4);
c2860d43 413 regs->uregs[rd2] = val;
f21ee2d4
SL		 414 } else {
415 put32_unaligned_check(regs->uregs[rd], addr);
c2860d43 416 put32_unaligned_check(regs->uregs[rd2], addr + 4);
f21ee2d4
SL		 417 }
418
419 return TYPE_LDST;
420
421 user:
c2860d43 422 if (load) {
f21ee2d4
SL		 423 unsigned long val;
424 get32t_unaligned_check(val, addr);
425 regs->uregs[rd] = val;
737d0bb7 426 get32t_unaligned_check(val, addr + 4);
c2860d43 427 regs->uregs[rd2] = val;
f21ee2d4
SL		 428 } else {
429 put32t_unaligned_check(regs->uregs[rd], addr);
c2860d43 430 put32t_unaligned_check(regs->uregs[rd2], addr + 4);
f21ee2d4
SL		 431 }
432
433 return TYPE_LDST;
19da83f6
GD		 434 bad:
435 return TYPE_ERROR;
1da177e4
LT		 436 fault:
437 return TYPE_FAULT;
438}
439
440static int
441do_alignment_ldrstr(unsigned long addr, unsigned long instr, struct pt_regs *regs)
442{
443 unsigned int rd = RD_BITS(instr);
444
445 ai_word += 1;
446
447 if ((!LDST_P_BIT(instr) && LDST_W_BIT(instr)) || user_mode(regs))
448 goto trans;
449
450 if (LDST_L_BIT(instr)) {
451 unsigned int val;
452 get32_unaligned_check(val, addr);
453 regs->uregs[rd] = val;
454 } else
455 put32_unaligned_check(regs->uregs[rd], addr);
456 return TYPE_LDST;
457
458 trans:
459 if (LDST_L_BIT(instr)) {
460 unsigned int val;
461 get32t_unaligned_check(val, addr);
462 regs->uregs[rd] = val;
463 } else
464 put32t_unaligned_check(regs->uregs[rd], addr);
465 return TYPE_LDST;
466
467 fault:
468 return TYPE_FAULT;
469}
470
471/*
472 * LDM/STM alignment handler.
473 *
474 * There are 4 variants of this instruction:
475 *
476 * B = rn pointer before instruction, A = rn pointer after instruction
477 * ------ increasing address ----->
478 * | | r0 | r1 | ... | rx | |
479 * PU = 01 B A
480 * PU = 11 B A
481 * PU = 00 A B
482 * PU = 10 A B
483 */
484static int
485do_alignment_ldmstm(unsigned long addr, unsigned long instr, struct pt_regs *regs)
486{
487 unsigned int rd, rn, correction, nr_regs, regbits;
488 unsigned long eaddr, newaddr;
489
490 if (LDM_S_BIT(instr))
491 goto bad;
492
493 correction = 4; /* processor implementation defined */
494 regs->ARM_pc += correction;
495
496 ai_multi += 1;
497
498 /* count the number of registers in the mask to be transferred */
499 nr_regs = hweight16(REGMASK_BITS(instr)) * 4;
500
501 rn = RN_BITS(instr);
502 newaddr = eaddr = regs->uregs[rn];
503
504 if (!LDST_U_BIT(instr))
505 nr_regs = -nr_regs;
506 newaddr += nr_regs;
507 if (!LDST_U_BIT(instr))
508 eaddr = newaddr;
509
510 if (LDST_P_EQ_U(instr)) /* U = P */
511 eaddr += 4;
512
737d0bb7 513 /*
1da177e4
LT		 514 * For alignment faults on the ARM922T/ARM920T the MMU makes
515 * the FSR (and hence addr) equal to the updated base address
516 * of the multiple access rather than the restored value.
517 * Switch this message off if we've got a ARM92[02], otherwise
518 * [ls]dm alignment faults are noisy!
519 */
520#if !(defined CONFIG_CPU_ARM922T) && !(defined CONFIG_CPU_ARM920T)
521 /*
522 * This is a "hint" - we already have eaddr worked out by the
523 * processor for us.
524 */
525 if (addr != eaddr) {
4ed89f22 526 pr_err("LDMSTM: PC = %08lx, instr = %08lx, "
1da177e4
LT		 527 "addr = %08lx, eaddr = %08lx\n",
528 instruction_pointer(regs), instr, addr, eaddr);
529 show_regs(regs);
530 }
531#endif
532
533 if (user_mode(regs)) {
534 for (regbits = REGMASK_BITS(instr), rd = 0; regbits;
535 regbits >>= 1, rd += 1)
536 if (regbits & 1) {
537 if (LDST_L_BIT(instr)) {
538 unsigned int val;
539 get32t_unaligned_check(val, eaddr);
540 regs->uregs[rd] = val;
541 } else
542 put32t_unaligned_check(regs->uregs[rd], eaddr);
543 eaddr += 4;
544 }
545 } else {
546 for (regbits = REGMASK_BITS(instr), rd = 0; regbits;
547 regbits >>= 1, rd += 1)
548 if (regbits & 1) {
549 if (LDST_L_BIT(instr)) {
550 unsigned int val;
551 get32_unaligned_check(val, eaddr);
552 regs->uregs[rd] = val;
553 } else
554 put32_unaligned_check(regs->uregs[rd], eaddr);
555 eaddr += 4;
556 }
557 }
558
559 if (LDST_W_BIT(instr))
560 regs->uregs[rn] = newaddr;
561 if (!LDST_L_BIT(instr) || !(REGMASK_BITS(instr) & (1 << 15)))
562 regs->ARM_pc -= correction;
563 return TYPE_DONE;
564
565fault:
566 regs->ARM_pc -= correction;
567 return TYPE_FAULT;
568
569bad:
4ed89f22 570 pr_err("Alignment trap: not handling ldm with s-bit set\n");
1da177e4
LT		 571 return TYPE_ERROR;
572}
573
574/*
575 * Convert Thumb ld/st instruction forms to equivalent ARM instructions so
576 * we can reuse ARM userland alignment fault fixups for Thumb.
577 *
578 * This implementation was initially based on the algorithm found in
579 * gdb/sim/arm/thumbemu.c. It is basically just a code reduction of same
580 * to convert only Thumb ld/st instruction forms to equivalent ARM forms.
581 *
582 * NOTES:
583 * 1. Comments below refer to ARM ARM DDI0100E Thumb Instruction sections.
584 * 2. If for some reason we're passed an non-ld/st Thumb instruction to
585 * decode, we return 0xdeadc0de. This should never happen under normal
586 * circumstances but if it does, we've got other problems to deal with
587 * elsewhere and we obviously can't fix those problems here.
588 */
589
590static unsigned long
591thumb2arm(u16 tinstr)
592{
593 u32 L = (tinstr & (1<<11)) >> 11;
594
595 switch ((tinstr & 0xf800) >> 11) {
596 /* 6.5.1 Format 1: */
597 case 0x6000 >> 11: /* 7.1.52 STR(1) */
598 case 0x6800 >> 11: /* 7.1.26 LDR(1) */
599 case 0x7000 >> 11: /* 7.1.55 STRB(1) */
600 case 0x7800 >> 11: /* 7.1.30 LDRB(1) */
601 return 0xe5800000 |
602 ((tinstr & (1<<12)) << (22-12)) | /* fixup */
603 (L<<20) | /* L==1? */
604 ((tinstr & (7<<0)) << (12-0)) | /* Rd */
605 ((tinstr & (7<<3)) << (16-3)) | /* Rn */
606 ((tinstr & (31<<6)) >> /* immed_5 */
607 (6 - ((tinstr & (1<<12)) ? 0 : 2)));
608 case 0x8000 >> 11: /* 7.1.57 STRH(1) */
609 case 0x8800 >> 11: /* 7.1.32 LDRH(1) */
610 return 0xe1c000b0 |
611 (L<<20) | /* L==1? */
612 ((tinstr & (7<<0)) << (12-0)) | /* Rd */
613 ((tinstr & (7<<3)) << (16-3)) | /* Rn */
614 ((tinstr & (7<<6)) >> (6-1)) | /* immed_5[2:0] */
615 ((tinstr & (3<<9)) >> (9-8)); /* immed_5[4:3] */
616
617 /* 6.5.1 Format 2: */
618 case 0x5000 >> 11:
619 case 0x5800 >> 11:
620 {
621 static const u32 subset[8] = {
622 0xe7800000, /* 7.1.53 STR(2) */
623 0xe18000b0, /* 7.1.58 STRH(2) */
624 0xe7c00000, /* 7.1.56 STRB(2) */
625 0xe19000d0, /* 7.1.34 LDRSB */
626 0xe7900000, /* 7.1.27 LDR(2) */
627 0xe19000b0, /* 7.1.33 LDRH(2) */
628 0xe7d00000, /* 7.1.31 LDRB(2) */
629 0xe19000f0 /* 7.1.35 LDRSH */
630 };
631 return subset[(tinstr & (7<<9)) >> 9] |
632 ((tinstr & (7<<0)) << (12-0)) | /* Rd */
633 ((tinstr & (7<<3)) << (16-3)) | /* Rn */
634 ((tinstr & (7<<6)) >> (6-0)); /* Rm */
635 }
636
637 /* 6.5.1 Format 3: */
638 case 0x4800 >> 11: /* 7.1.28 LDR(3) */
639 /* NOTE: This case is not technically possible. We're
737d0bb7 640 * loading 32-bit memory data via PC relative
1da177e4
LT		 641 * addressing mode. So we can and should eliminate
642 * this case. But I'll leave it here for now.
643 */
644 return 0xe59f0000 |
645 ((tinstr & (7<<8)) << (12-8)) | /* Rd */
646 ((tinstr & 255) << (2-0)); /* immed_8 */
647
648 /* 6.5.1 Format 4: */
649 case 0x9000 >> 11: /* 7.1.54 STR(3) */
650 case 0x9800 >> 11: /* 7.1.29 LDR(4) */
651 return 0xe58d0000 |
652 (L<<20) | /* L==1? */
653 ((tinstr & (7<<8)) << (12-8)) | /* Rd */
654 ((tinstr & 255) << 2); /* immed_8 */
655
656 /* 6.6.1 Format 1: */
657 case 0xc000 >> 11: /* 7.1.51 STMIA */
658 case 0xc800 >> 11: /* 7.1.25 LDMIA */
659 {
660 u32 Rn = (tinstr & (7<<8)) >> 8;
661 u32 W = ((L<<Rn) & (tinstr&255)) ? 0 : 1<<21;
662
663 return 0xe8800000 | W | (L<<20) | (Rn<<16) |
664 (tinstr&255);
665 }
666
667 /* 6.6.1 Format 2: */
668 case 0xb000 >> 11: /* 7.1.48 PUSH */
669 case 0xb800 >> 11: /* 7.1.47 POP */
670 if ((tinstr & (3 << 9)) == 0x0400) {
671 static const u32 subset[4] = {
672 0xe92d0000, /* STMDB sp!,{registers} */
673 0xe92d4000, /* STMDB sp!,{registers,lr} */
674 0xe8bd0000, /* LDMIA sp!,{registers} */
675 0xe8bd8000 /* LDMIA sp!,{registers,pc} */
676 };
677 return subset[(L<<1) | ((tinstr & (1<<8)) >> 8)] |
678 (tinstr & 255); /* register_list */
679 }
680 /* Else fall through for illegal instruction case */
681
682 default:
c2860d43
GD		 683 return BAD_INSTR;
684 }
685}
686
687/*
688 * Convert Thumb-2 32 bit LDM, STM, LDRD, STRD to equivalent instruction
689 * handlable by ARM alignment handler, also find the corresponding handler,
690 * so that we can reuse ARM userland alignment fault fixups for Thumb.
691 *
692 * @pinstr: original Thumb-2 instruction; returns new handlable instruction
693 * @regs: register context.
694 * @poffset: return offset from faulted addr for later writeback
695 *
696 * NOTES:
697 * 1. Comments below refer to ARMv7 DDI0406A Thumb Instruction sections.
698 * 2. Register name Rt from ARMv7 is same as Rd from ARMv6 (Rd is Rt)
699 */
700static void *
701do_alignment_t32_to_handler(unsigned long *pinstr, struct pt_regs *regs,
702 union offset_union *poffset)
703{
704 unsigned long instr = *pinstr;
705 u16 tinst1 = (instr >> 16) & 0xffff;
706 u16 tinst2 = instr & 0xffff;
c2860d43
GD		 707
708 switch (tinst1 & 0xffe0) {
709 /* A6.3.5 Load/Store multiple */
710 case 0xe880: /* STM/STMIA/STMEA,LDM/LDMIA, PUSH/POP T2 */
711 case 0xe8a0: /* ...above writeback version */
712 case 0xe900: /* STMDB/STMFD, LDMDB/LDMEA */
713 case 0xe920: /* ...above writeback version */
714 /* no need offset decision since handler calculates it */
715 return do_alignment_ldmstm;
716
717 case 0xf840: /* POP/PUSH T3 (single register) */
718 if (RN_BITS(instr) == 13 && (tinst2 & 0x09ff) == 0x0904) {
719 u32 L = !!(LDST_L_BIT(instr));
720 const u32 subset[2] = {
721 0xe92d0000, /* STMDB sp!,{registers} */
722 0xe8bd0000, /* LDMIA sp!,{registers} */
723 };
724 *pinstr = subset[L] | (1<<RD_BITS(instr));
725 return do_alignment_ldmstm;
726 }
727 /* Else fall through for illegal instruction case */
728 break;
729
730 /* A6.3.6 Load/store double, STRD/LDRD(immed, lit, reg) */
731 case 0xe860:
732 case 0xe960:
733 case 0xe8e0:
734 case 0xe9e0:
735 poffset->un = (tinst2 & 0xff) << 2;
736 case 0xe940:
737 case 0xe9c0:
738 return do_alignment_ldrdstrd;
739
740 /*
741 * No need to handle load/store instructions up to word size
742 * since ARMv6 and later CPUs can perform unaligned accesses.
743 */
744 default:
745 break;
1da177e4 746 }
c2860d43 747 return NULL;
1da177e4
LT		 748}
749
750static int
751do_alignment(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
752{
6404f0b7 753 union offset_union uninitialized_var(offset);
1da177e4
LT		 754 unsigned long instr = 0, instrptr;
755 int (*handler)(unsigned long addr, unsigned long instr, struct pt_regs *regs);
756 unsigned int type;
1da177e4
LT		 757 unsigned int fault;
758 u16 tinstr = 0;
c2860d43
GD		 759 int isize = 4;
760 int thumb2_32b = 0;
1da177e4 761
02fe2845
RK		 762 if (interrupts_enabled(regs))
763 local_irq_enable();
764
1da177e4
LT		 765 instrptr = instruction_pointer(regs);
766
f8343685 767 if (thumb_mode(regs)) {
b255188f
RK		 768 u16 *ptr = (u16 *)(instrptr & ~1);
769 fault = probe_kernel_address(ptr, tinstr);
8592edf0 770 tinstr = __mem_to_opcode_thumb16(tinstr);
c2860d43
GD		 771 if (!fault) {
772 if (cpu_architecture() >= CPU_ARCH_ARMv7 &&
773 IS_T32(tinstr)) {
774 /* Thumb-2 32-bit */
775 u16 tinst2 = 0;
b255188f 776 fault = probe_kernel_address(ptr + 1, tinst2);
8592edf0
BD		 777 tinst2 = __mem_to_opcode_thumb16(tinst2);
778 instr = __opcode_thumb32_compose(tinstr, tinst2);
c2860d43
GD		 779 thumb2_32b = 1;
780 } else {
781 isize = 2;
782 instr = thumb2arm(tinstr);
783 }
784 }
8592edf0 785 } else {
b255188f 786 fault = probe_kernel_address(instrptr, instr);
8592edf0
BD		 787 instr = __mem_to_opcode_arm(instr);
788 }
1da177e4
LT		 789
790 if (fault) {
791 type = TYPE_FAULT;
737d0bb7 792 goto bad_or_fault;
1da177e4
LT		 793 }
794
795 if (user_mode(regs))
796 goto user;
797
798 ai_sys += 1;
1e7e3211 799 ai_sys_last_pc = (void *)instruction_pointer(regs);
1da177e4
LT		 800
801 fixup:
802
c2860d43 803 regs->ARM_pc += isize;
1da177e4
LT		 804
805 switch (CODING_BITS(instr)) {
f21ee2d4
SL		 806 case 0x00000000: /* 3.13.4 load/store instruction extensions */
807 if (LDSTHD_I_BIT(instr))
1da177e4
LT		 808 offset.un = (instr & 0xf00) >> 4 | (instr & 15);
809 else
810 offset.un = regs->uregs[RM_BITS(instr)];
f21ee2d4
SL		 811
812 if ((instr & 0x000000f0) == 0x000000b0 || /* LDRH, STRH */
813 (instr & 0x001000f0) == 0x001000f0) /* LDRSH */
814 handler = do_alignment_ldrhstrh;
815 else if ((instr & 0x001000f0) == 0x000000d0 || /* LDRD */
816 (instr & 0x001000f0) == 0x000000f0) /* STRD */
817 handler = do_alignment_ldrdstrd;
19da83f6
GD		 818 else if ((instr & 0x01f00ff0) == 0x01000090) /* SWP */
819 goto swp;
f21ee2d4
SL		 820 else
821 goto bad;
1da177e4
LT		 822 break;
823
824 case 0x04000000: /* ldr or str immediate */
5ca918e5
RM		 825 if (COND_BITS(instr) == 0xf0000000) /* NEON VLDn, VSTn */
826 goto bad;
1da177e4
LT		 827 offset.un = OFFSET_BITS(instr);
828 handler = do_alignment_ldrstr;
829 break;
830
831 case 0x06000000: /* ldr or str register */
832 offset.un = regs->uregs[RM_BITS(instr)];
833
834 if (IS_SHIFT(instr)) {
835 unsigned int shiftval = SHIFT_BITS(instr);
836
837 switch(SHIFT_TYPE(instr)) {
838 case SHIFT_LSL:
839 offset.un <<= shiftval;
840 break;
841
842 case SHIFT_LSR:
843 offset.un >>= shiftval;
844 break;
845
846 case SHIFT_ASR:
847 offset.sn >>= shiftval;
848 break;
849
850 case SHIFT_RORRRX:
851 if (shiftval == 0) {
852 offset.un >>= 1;
853 if (regs->ARM_cpsr & PSR_C_BIT)
854 offset.un |= 1 << 31;
855 } else
856 offset.un = offset.un >> shiftval |
857 offset.un << (32 - shiftval);
858 break;
859 }
860 }
861 handler = do_alignment_ldrstr;
862 break;
863
c2860d43 864 case 0x08000000: /* ldm or stm, or thumb-2 32bit instruction */
a761cebf
RK		 865 if (thumb2_32b) {
866 offset.un = 0;
c2860d43 867 handler = do_alignment_t32_to_handler(&instr, regs, &offset);
31d2a638
AB		 868 } else {
869 offset.un = 0;
c2860d43 870 handler = do_alignment_ldmstm;
31d2a638 871 }
1da177e4
LT		 872 break;
873
874 default:
875 goto bad;
876 }
877
c2860d43
GD		 878 if (!handler)
879 goto bad;
1da177e4
LT		 880 type = handler(addr, instr, regs);
881
c2860d43
GD		 882 if (type == TYPE_ERROR || type == TYPE_FAULT) {
883 regs->ARM_pc -= isize;
1da177e4 884 goto bad_or_fault;
c2860d43 885 }
1da177e4
LT		 886
887 if (type == TYPE_LDST)
888 do_alignment_finish_ldst(addr, instr, regs, offset);
889
890 return 0;
891
892 bad_or_fault:
893 if (type == TYPE_ERROR)
894 goto bad;
1da177e4
LT		 895 /*
896 * We got a fault - fix it up, or die.
897 */
e5beac37 898 do_bad_area(addr, fsr, regs);
1da177e4
LT		 899 return 0;
900
19da83f6 901 swp:
4ed89f22 902 pr_err("Alignment trap: not handling swp instruction\n");
19da83f6 903
1da177e4
LT		 904 bad:
905 /*
906 * Oops, we didn't handle the instruction.
907 */
4ed89f22 908 pr_err("Alignment trap: not handling instruction "
1da177e4 909 "%0*lx at [<%08lx>]\n",
c2860d43
GD		 910 isize << 1,
911 isize == 2 ? tinstr : instr, instrptr);
1da177e4
LT		 912 ai_skipped += 1;
913 return 1;
914
915 user:
916 ai_user += 1;
917
baa745a3 918 if (ai_usermode & UM_WARN)
1da177e4
LT		 919 printk("Alignment trap: %s (%d) PC=0x%08lx Instr=0x%0*lx "
920 "Address=0x%08lx FSR 0x%03x\n", current->comm,
19c5870c 921 task_pid_nr(current), instrptr,
c2860d43
GD		 922 isize << 1,
923 isize == 2 ? tinstr : instr,
1da177e4
LT		 924 addr, fsr);
925
baa745a3 926 if (ai_usermode & UM_FIXUP)
1da177e4
LT		 927 goto fixup;
928
2102a65e
DM		 929 if (ai_usermode & UM_SIGNAL) {
930 siginfo_t si;
931
932 si.si_signo = SIGBUS;
933 si.si_errno = 0;
934 si.si_code = BUS_ADRALN;
935 si.si_addr = (void __user *)addr;
936
937 force_sig_info(si.si_signo, &si, current);
938 } else {
2f27bf83
NP		 939 /*
940 * We're about to disable the alignment trap and return to
941 * user space. But if an interrupt occurs before actually
942 * reaching user space, then the IRQ vector entry code will
943 * notice that we were still in kernel space and therefore
944 * the alignment trap won't be re-enabled in that case as it
945 * is presumed to be always on from kernel space.
946 * Let's prevent that race by disabling interrupts here (they
947 * are disabled on the way back to user space anyway in
948 * entry-common.S) and disable the alignment trap only if
949 * there is no work pending for this thread.
950 */
951 raw_local_irq_disable();
952 if (!(current_thread_info()->flags & _TIF_WORK_MASK))
953 set_cr(cr_no_alignment);
954 }
1da177e4
LT		 955
956 return 0;
957}
958
175352a5
RK		 959static int __init noalign_setup(char *__unused)
960{
961 set_cr(__clear_cr(CR_A));
962 return 1;
963}
964__setup("noalign", noalign_setup);
965
1da177e4
LT		 966/*
967 * This needs to be done after sysctl_init, otherwise sys/ will be
968 * overwritten. Actually, this shouldn't be in sys/ at all since
969 * it isn't a sysctl, and it doesn't contain sysctl information.
970 * We now locate it in /proc/cpu/alignment instead.
971 */
972static int __init alignment_init(void)
973{
974#ifdef CONFIG_PROC_FS
975 struct proc_dir_entry *res;
976
b7072c63
AD		 977 res = proc_create("cpu/alignment", S_IWUSR | S_IRUGO, NULL,
978 &alignment_proc_fops);
1da177e4
LT		 979 if (!res)
980 return -ENOMEM;
1da177e4
LT		 981#endif
982
088c01f1 983 if (cpu_is_v6_unaligned()) {
b4b20ad8 984 set_cr(__clear_cr(CR_A));
088c01f1 985 ai_usermode = safe_usermode(ai_usermode, false);
baa745a3
RK		 986 }
987
0aeb3408
RK		 988 cr_no_alignment = get_cr() & ~CR_A;
989
f7b8156d 990 hook_fault_code(FAULT_CODE_ALIGNMENT, do_alignment, SIGBUS, BUS_ADRALN,
6338a6aa 991 "alignment exception");
b8ab5397
KS		 992
993 /*
994 * ARMv6K and ARMv7 use fault status 3 (0b00011) as Access Flag section
995 * fault, not as alignment error.
996 *
997 * TODO: handle ARMv6K properly. Runtime check for 'K' extension is
998 * needed.
999 */
1000 if (cpu_architecture() <= CPU_ARCH_ARMv6) {
1001 hook_fault_code(3, do_alignment, SIGBUS, BUS_ADRALN,
1002 "alignment exception");
1003 }
1da177e4
LT		 1004
1005 return 0;
1006}
1007
1008fs_initcall(alignment_init);
Linux kernel - Deliverables
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