| blob | 995a2123635bc2dbb0d9121e500e0dc6ead4494c |
1 /*
2 * Exception handling for Microblaze
3 *
4 * Rewriten interrupt handling
5 *
6 * Copyright (C) 2008-2009 Michal Simek <monstr@monstr.eu>
7 * Copyright (C) 2008-2009 PetaLogix
8 *
9 * uClinux customisation (C) 2005 John Williams
10 *
11 * MMU code derived from arch/ppc/kernel/head_4xx.S:
12 * Copyright (C) 1995-1996 Gary Thomas <gdt@linuxppc.org>
13 * Initial PowerPC version.
14 * Copyright (C) 1996 Cort Dougan <cort@cs.nmt.edu>
15 * Rewritten for PReP
16 * Copyright (C) 1996 Paul Mackerras <paulus@cs.anu.edu.au>
17 * Low-level exception handers, MMU support, and rewrite.
18 * Copyright (C) 1997 Dan Malek <dmalek@jlc.net>
19 * PowerPC 8xx modifications.
20 * Copyright (C) 1998-1999 TiVo, Inc.
21 * PowerPC 403GCX modifications.
22 * Copyright (C) 1999 Grant Erickson <grant@lcse.umn.edu>
23 * PowerPC 403GCX/405GP modifications.
24 * Copyright 2000 MontaVista Software Inc.
25 * PPC405 modifications
26 * PowerPC 403GCX/405GP modifications.
27 * Author: MontaVista Software, Inc.
28 * frank_rowand@mvista.com or source@mvista.com
29 * debbie_chu@mvista.com
30 *
31 * Original code
32 * Copyright (C) 2004 Xilinx, Inc.
33 *
34 * This program is free software; you can redistribute it and/or modify it
35 * under the terms of the GNU General Public License version 2 as published
36 * by the Free Software Foundation.
37 */
39 /*
40 * Here are the handlers which don't require enabling translation
41 * and calling other kernel code thus we can keep their design very simple
42 * and do all processing in real mode. All what they need is a valid current
43 * (that is an issue for the CONFIG_REGISTER_TASK_PTR case)
44 * This handlers use r3,r4,r5,r6 and optionally r[current] to work therefore
45 * these registers are saved/restored
46 * The handlers which require translation are in entry.S --KAA
47 *
48 * Microblaze HW Exception Handler
49 * - Non self-modifying exception handler for the following exception conditions
50 * - Unalignment
51 * - Instruction bus error
52 * - Data bus error
53 * - Illegal instruction opcode
54 * - Divide-by-zero
55 *
56 * - Privileged instruction exception (MMU)
57 * - Data storage exception (MMU)
58 * - Instruction storage exception (MMU)
59 * - Data TLB miss exception (MMU)
60 * - Instruction TLB miss exception (MMU)
61 *
62 * Note we disable interrupts during exception handling, otherwise we will
63 * possibly get multiple re-entrancy if interrupt handles themselves cause
64 * exceptions. JW
65 */
67 #include <asm/exceptions.h>
68 #include <asm/unistd.h>
69 #include <asm/page.h>
71 #include <asm/entry.h>
72 #include <asm/current.h>
73 #include <linux/linkage.h>
75 #include <asm/mmu.h>
76 #include <asm/pgtable.h>
77 #include <asm/signal.h>
78 #include <asm/asm-offsets.h>
80 /* Helpful Macros */
81 #ifndef CONFIG_MMU
82 #define EX_HANDLER_STACK_SIZ (4*19)
83 #endif
84 #define NUM_TO_REG(num) r ## num
86 #ifdef CONFIG_MMU
87 #define RESTORE_STATE \
88 lwi r5, r1, 0; \
89 mts rmsr, r5; \
90 nop; \
91 lwi r3, r1, PT_R3; \
92 lwi r4, r1, PT_R4; \
93 lwi r5, r1, PT_R5; \
94 lwi r6, r1, PT_R6; \
95 lwi r11, r1, PT_R11; \
96 lwi r31, r1, PT_R31; \
97 lwi r1, r0, TOPHYS(r0_ram + 0);
98 #endif /* CONFIG_MMU */
100 #define LWREG_NOP \
101 bri ex_handler_unhandled; \
102 nop;
104 #define SWREG_NOP \
105 bri ex_handler_unhandled; \
106 nop;
108 /* FIXME this is weird - for noMMU kernel is not possible to use brid
109 * instruction which can shorten executed time
110 */
112 /* r3 is the source */
113 #define R3_TO_LWREG_V(regnum) \
114 swi r3, r1, 4 * regnum; \
115 bri ex_handler_done;
117 /* r3 is the source */
118 #define R3_TO_LWREG(regnum) \
119 or NUM_TO_REG (regnum), r0, r3; \
120 bri ex_handler_done;
122 /* r3 is the target */
123 #define SWREG_TO_R3_V(regnum) \
124 lwi r3, r1, 4 * regnum; \
125 bri ex_sw_tail;
127 /* r3 is the target */
128 #define SWREG_TO_R3(regnum) \
129 or r3, r0, NUM_TO_REG (regnum); \
130 bri ex_sw_tail;
132 #ifdef CONFIG_MMU
133 #define R3_TO_LWREG_VM_V(regnum) \
134 brid ex_lw_end_vm; \
135 swi r3, r7, 4 * regnum;
137 #define R3_TO_LWREG_VM(regnum) \
138 brid ex_lw_end_vm; \
139 or NUM_TO_REG (regnum), r0, r3;
141 #define SWREG_TO_R3_VM_V(regnum) \
142 brid ex_sw_tail_vm; \
143 lwi r3, r7, 4 * regnum;
145 #define SWREG_TO_R3_VM(regnum) \
146 brid ex_sw_tail_vm; \
147 or r3, r0, NUM_TO_REG (regnum);
149 /* Shift right instruction depending on available configuration */
150 #if CONFIG_XILINX_MICROBLAZE0_USE_BARREL > 0
151 #define BSRLI(rD, rA, imm) \
152 bsrli rD, rA, imm
153 #elif CONFIG_XILINX_MICROBLAZE0_USE_DIV > 0
154 #define BSRLI(rD, rA, imm) \
155 ori rD, r0, (1 << imm); \
156 idivu rD, rD, rA
157 #else
158 #define BSRLI(rD, rA, imm) BSRLI ## imm (rD, rA)
159 /* Only the used shift constants defined here - add more if needed */
160 #define BSRLI2(rD, rA) \
161 srl rD, rA; /* << 1 */ \
162 srl rD, rD; /* << 2 */
163 #define BSRLI10(rD, rA) \
164 srl rD, rA; /* << 1 */ \
165 srl rD, rD; /* << 2 */ \
166 srl rD, rD; /* << 3 */ \
167 srl rD, rD; /* << 4 */ \
168 srl rD, rD; /* << 5 */ \
169 srl rD, rD; /* << 6 */ \
170 srl rD, rD; /* << 7 */ \
171 srl rD, rD; /* << 8 */ \
172 srl rD, rD; /* << 9 */ \
173 srl rD, rD /* << 10 */
174 #define BSRLI20(rD, rA) \
175 BSRLI10(rD, rA); \
176 BSRLI10(rD, rD)
177 #endif
178 #endif /* CONFIG_MMU */
180 .extern other_exception_handler /* Defined in exception.c */
182 /*
183 * hw_exception_handler - Handler for exceptions
184 *
185 * Exception handler notes:
186 * - Handles all exceptions
187 * - Does not handle unaligned exceptions during load into r17, r1, r0.
188 * - Does not handle unaligned exceptions during store from r17 (cannot be
189 * done) and r1 (slows down common case)
190 *
191 * Relevant register structures
192 *
193 * EAR - |----|----|----|----|----|----|----|----|
194 * - < ## 32 bit faulting address ## >
195 *
196 * ESR - |----|----|----|----|----| - | - |-----|-----|
197 * - W S REG EXC
198 *
199 *
200 * STACK FRAME STRUCTURE (for NO_MMU)
201 * ---------------------------------
202 *
203 * +-------------+ + 0
204 * | MSR |
205 * +-------------+ + 4
206 * | r1 |
207 * | . |
208 * | . |
209 * | . |
210 * | . |
211 * | r18 |
212 * +-------------+ + 76
213 * | . |
214 * | . |
215 *
216 * NO_MMU kernel use the same r0_ram pointed space - look to vmlinux.lds.S
217 * which is used for storing register values - old style was, that value were
218 * stored in stack but in case of failure you lost information about register.
219 * Currently you can see register value in memory in specific place.
220 * In compare to with previous solution the speed should be the same.
221 *
222 * MMU exception handler has different handling compare to no MMU kernel.
223 * Exception handler use jump table for directing of what happen. For MMU kernel
224 * is this approach better because MMU relate exception are handled by asm code
225 * in this file. In compare to with MMU expect of unaligned exception
226 * is everything handled by C code.
227 */
229 /*
230 * every of these handlers is entered having R3/4/5/6/11/current saved on stack
231 * and clobbered so care should be taken to restore them if someone is going to
232 * return from exception
233 */
235 /* wrappers to restore state before coming to entry.S */
237 #ifdef CONFIG_MMU
238 .section .rodata
239 .align 4
240 _MB_HW_ExceptionVectorTable:
241 /* 0 - Undefined */
242 .long TOPHYS(ex_handler_unhandled)
243 /* 1 - Unaligned data access exception */
244 .long TOPHYS(handle_unaligned_ex)
245 /* 2 - Illegal op-code exception */
246 .long TOPHYS(full_exception_trapw)
247 /* 3 - Instruction bus error exception */
248 .long TOPHYS(full_exception_trapw)
249 /* 4 - Data bus error exception */
250 .long TOPHYS(full_exception_trapw)
251 /* 5 - Divide by zero exception */
252 .long TOPHYS(full_exception_trapw)
253 /* 6 - Floating point unit exception */
254 .long TOPHYS(full_exception_trapw)
255 /* 7 - Privileged instruction exception */
256 .long TOPHYS(full_exception_trapw)
257 /* 8 - 15 - Undefined */
258 .long TOPHYS(ex_handler_unhandled)
259 .long TOPHYS(ex_handler_unhandled)
260 .long TOPHYS(ex_handler_unhandled)
261 .long TOPHYS(ex_handler_unhandled)
262 .long TOPHYS(ex_handler_unhandled)
263 .long TOPHYS(ex_handler_unhandled)
264 .long TOPHYS(ex_handler_unhandled)
265 .long TOPHYS(ex_handler_unhandled)
266 /* 16 - Data storage exception */
267 .long TOPHYS(handle_data_storage_exception)
268 /* 17 - Instruction storage exception */
269 .long TOPHYS(handle_instruction_storage_exception)
270 /* 18 - Data TLB miss exception */
271 .long TOPHYS(handle_data_tlb_miss_exception)
272 /* 19 - Instruction TLB miss exception */
273 .long TOPHYS(handle_instruction_tlb_miss_exception)
274 /* 20 - 31 - Undefined */
275 .long TOPHYS(ex_handler_unhandled)
276 .long TOPHYS(ex_handler_unhandled)
277 .long TOPHYS(ex_handler_unhandled)
278 .long TOPHYS(ex_handler_unhandled)
279 .long TOPHYS(ex_handler_unhandled)
280 .long TOPHYS(ex_handler_unhandled)
281 .long TOPHYS(ex_handler_unhandled)
282 .long TOPHYS(ex_handler_unhandled)
283 .long TOPHYS(ex_handler_unhandled)
284 .long TOPHYS(ex_handler_unhandled)
285 .long TOPHYS(ex_handler_unhandled)
286 .long TOPHYS(ex_handler_unhandled)
287 #endif
289 .global _hw_exception_handler
290 .section .text
291 .align 4
292 .ent _hw_exception_handler
293 _hw_exception_handler:
294 #ifndef CONFIG_MMU
295 addik r1, r1, -(EX_HANDLER_STACK_SIZ); /* Create stack frame */
296 #else
297 swi r1, r0, TOPHYS(r0_ram + 0); /* GET_SP */
298 /* Save date to kernel memory. Here is the problem
299 * when you came from user space */
300 ori r1, r0, TOPHYS(r0_ram + 28);
301 #endif
302 swi r3, r1, PT_R3
303 swi r4, r1, PT_R4
304 swi r5, r1, PT_R5
305 swi r6, r1, PT_R6
307 #ifdef CONFIG_MMU
308 swi r11, r1, PT_R11
309 swi r31, r1, PT_R31
310 lwi r31, r0, TOPHYS(PER_CPU(CURRENT_SAVE)) /* get saved current */
311 #endif
313 mfs r5, rmsr;
314 nop
315 swi r5, r1, 0;
316 mfs r4, resr
317 nop
318 mfs r3, rear;
319 nop
321 #ifndef CONFIG_MMU
322 andi r5, r4, 0x1000; /* Check ESR[DS] */
323 beqi r5, not_in_delay_slot; /* Branch if ESR[DS] not set */
324 mfs r17, rbtr; /* ESR[DS] set - return address in BTR */
325 nop
326 not_in_delay_slot:
327 swi r17, r1, PT_R17
328 #endif
330 andi r5, r4, 0x1F; /* Extract ESR[EXC] */
332 #ifdef CONFIG_MMU
333 /* Calculate exception vector offset = r5 << 2 */
334 addk r6, r5, r5; /* << 1 */
335 addk r6, r6, r6; /* << 2 */
337 #ifdef DEBUG
338 /* counting which exception happen */
339 lwi r5, r0, 0x200 + TOPHYS(r0_ram)
340 addi r5, r5, 1
341 swi r5, r0, 0x200 + TOPHYS(r0_ram)
342 lwi r5, r6, 0x200 + TOPHYS(r0_ram)
343 addi r5, r5, 1
344 swi r5, r6, 0x200 + TOPHYS(r0_ram)
345 #endif
346 /* end */
347 /* Load the HW Exception vector */
348 lwi r6, r6, TOPHYS(_MB_HW_ExceptionVectorTable)
349 bra r6
351 full_exception_trapw:
352 RESTORE_STATE
353 bri full_exception_trap
354 #else
355 /* Exceptions enabled here. This will allow nested exceptions */
356 mfs r6, rmsr;
357 nop
358 swi r6, r1, 0; /* RMSR_OFFSET */
359 ori r6, r6, 0x100; /* Turn ON the EE bit */
360 andi r6, r6, ~2; /* Disable interrupts */
361 mts rmsr, r6;
362 nop
364 xori r6, r5, 1; /* 00001 = Unaligned Exception */
365 /* Jump to unalignment exception handler */
366 beqi r6, handle_unaligned_ex;
368 handle_other_ex: /* Handle Other exceptions here */
369 /* Save other volatiles before we make procedure calls below */
370 swi r7, r1, PT_R7
371 swi r8, r1, PT_R8
372 swi r9, r1, PT_R9
373 swi r10, r1, PT_R10
374 swi r11, r1, PT_R11
375 swi r12, r1, PT_R12
376 swi r14, r1, PT_R14
377 swi r15, r1, PT_R15
378 swi r18, r1, PT_R18
380 or r5, r1, r0
381 andi r6, r4, 0x1F; /* Load ESR[EC] */
382 lwi r7, r0, PER_CPU(KM) /* MS: saving current kernel mode to regs */
383 swi r7, r1, PT_MODE
384 mfs r7, rfsr
385 nop
386 addk r8, r17, r0; /* Load exception address */
387 bralid r15, full_exception; /* Branch to the handler */
388 nop;
389 mts rfsr, r0; /* Clear sticky fsr */
390 nop
392 /*
393 * Trigger execution of the signal handler by enabling
394 * interrupts and calling an invalid syscall.
395 */
396 mfs r5, rmsr;
397 nop
398 ori r5, r5, 2;
399 mts rmsr, r5; /* enable interrupt */
400 nop
401 addi r12, r0, __NR_syscalls;
402 brki r14, 0x08;
403 mfs r5, rmsr; /* disable interrupt */
404 nop
405 andi r5, r5, ~2;
406 mts rmsr, r5;
407 nop
409 lwi r7, r1, PT_R7
410 lwi r8, r1, PT_R8
411 lwi r9, r1, PT_R9
412 lwi r10, r1, PT_R10
413 lwi r11, r1, PT_R11
414 lwi r12, r1, PT_R12
415 lwi r14, r1, PT_R14
416 lwi r15, r1, PT_R15
417 lwi r18, r1, PT_R18
419 bri ex_handler_done; /* Complete exception handling */
420 #endif
422 /* 0x01 - Unaligned data access exception
423 * This occurs when a word access is not aligned on a word boundary,
424 * or when a 16-bit access is not aligned on a 16-bit boundary.
425 * This handler perform the access, and returns, except for MMU when
426 * the unaligned address is last on a 4k page or the physical address is
427 * not found in the page table, in which case unaligned_data_trap is called.
428 */
429 handle_unaligned_ex:
430 /* Working registers already saved: R3, R4, R5, R6
431 * R4 = ESR
432 * R3 = EAR
433 */
434 #ifdef CONFIG_MMU
435 andi r6, r4, 0x1000 /* Check ESR[DS] */
436 beqi r6, _no_delayslot /* Branch if ESR[DS] not set */
437 mfs r17, rbtr; /* ESR[DS] set - return address in BTR */
438 nop
439 _no_delayslot:
440 /* jump to high level unaligned handler */
441 RESTORE_STATE;
442 bri unaligned_data_trap
443 #endif
444 andi r6, r4, 0x3E0; /* Mask and extract the register operand */
445 srl r6, r6; /* r6 >> 5 */
446 srl r6, r6;
447 srl r6, r6;
448 srl r6, r6;
449 srl r6, r6;
450 /* Store the register operand in a temporary location */
451 sbi r6, r0, TOPHYS(ex_reg_op);
453 andi r6, r4, 0x400; /* Extract ESR[S] */
454 bnei r6, ex_sw;
455 ex_lw:
456 andi r6, r4, 0x800; /* Extract ESR[W] */
457 beqi r6, ex_lhw;
458 lbui r5, r3, 0; /* Exception address in r3 */
459 /* Load a word, byte-by-byte from destination address
460 and save it in tmp space */
461 sbi r5, r0, TOPHYS(ex_tmp_data_loc_0);
462 lbui r5, r3, 1;
463 sbi r5, r0, TOPHYS(ex_tmp_data_loc_1);
464 lbui r5, r3, 2;
465 sbi r5, r0, TOPHYS(ex_tmp_data_loc_2);
466 lbui r5, r3, 3;
467 sbi r5, r0, TOPHYS(ex_tmp_data_loc_3);
468 /* Get the destination register value into r4 */
469 lwi r4, r0, TOPHYS(ex_tmp_data_loc_0);
470 bri ex_lw_tail;
471 ex_lhw:
472 lbui r5, r3, 0; /* Exception address in r3 */
473 /* Load a half-word, byte-by-byte from destination
474 address and save it in tmp space */
475 sbi r5, r0, TOPHYS(ex_tmp_data_loc_0);
476 lbui r5, r3, 1;
477 sbi r5, r0, TOPHYS(ex_tmp_data_loc_1);
478 /* Get the destination register value into r4 */
479 lhui r4, r0, TOPHYS(ex_tmp_data_loc_0);
480 ex_lw_tail:
481 /* Get the destination register number into r5 */
482 lbui r5, r0, TOPHYS(ex_reg_op);
483 /* Form load_word jump table offset (lw_table + (8 * regnum)) */
484 la r6, r0, TOPHYS(lw_table);
485 addk r5, r5, r5;
486 addk r5, r5, r5;
487 addk r5, r5, r5;
488 addk r5, r5, r6;
489 bra r5;
490 ex_lw_end: /* Exception handling of load word, ends */
491 ex_sw:
492 /* Get the destination register number into r5 */
493 lbui r5, r0, TOPHYS(ex_reg_op);
494 /* Form store_word jump table offset (sw_table + (8 * regnum)) */
495 la r6, r0, TOPHYS(sw_table);
496 add r5, r5, r5;
497 add r5, r5, r5;
498 add r5, r5, r5;
499 add r5, r5, r6;
500 bra r5;
501 ex_sw_tail:
502 mfs r6, resr;
503 nop
504 andi r6, r6, 0x800; /* Extract ESR[W] */
505 beqi r6, ex_shw;
506 /* Get the word - delay slot */
507 swi r4, r0, TOPHYS(ex_tmp_data_loc_0);
508 /* Store the word, byte-by-byte into destination address */
509 lbui r4, r0, TOPHYS(ex_tmp_data_loc_0);
510 sbi r4, r3, 0;
511 lbui r4, r0, TOPHYS(ex_tmp_data_loc_1);
512 sbi r4, r3, 1;
513 lbui r4, r0, TOPHYS(ex_tmp_data_loc_2);
514 sbi r4, r3, 2;
515 lbui r4, r0, TOPHYS(ex_tmp_data_loc_3);
516 sbi r4, r3, 3;
517 bri ex_handler_done;
519 ex_shw:
520 /* Store the lower half-word, byte-by-byte into destination address */
521 swi r4, r0, TOPHYS(ex_tmp_data_loc_0);
522 lbui r4, r0, TOPHYS(ex_tmp_data_loc_2);
523 sbi r4, r3, 0;
524 lbui r4, r0, TOPHYS(ex_tmp_data_loc_3);
525 sbi r4, r3, 1;
526 ex_sw_end: /* Exception handling of store word, ends. */
528 ex_handler_done:
529 #ifndef CONFIG_MMU
530 lwi r5, r1, 0 /* RMSR */
531 mts rmsr, r5
532 nop
533 lwi r3, r1, PT_R3
534 lwi r4, r1, PT_R4
535 lwi r5, r1, PT_R5
536 lwi r6, r1, PT_R6
537 lwi r17, r1, PT_R17
539 rted r17, 0
540 addik r1, r1, (EX_HANDLER_STACK_SIZ); /* Restore stack frame */
541 #else
542 RESTORE_STATE;
543 rted r17, 0
544 nop
545 #endif
547 #ifdef CONFIG_MMU
548 /* Exception vector entry code. This code runs with address translation
549 * turned off (i.e. using physical addresses). */
551 /* Exception vectors. */
553 /* 0x10 - Data Storage Exception
554 * This happens for just a few reasons. U0 set (but we don't do that),
555 * or zone protection fault (user violation, write to protected page).
556 * If this is just an update of modified status, we do that quickly
557 * and exit. Otherwise, we call heavyweight functions to do the work.
558 */
559 handle_data_storage_exception:
560 /* Working registers already saved: R3, R4, R5, R6
561 * R3 = ESR
562 */
563 mfs r11, rpid
564 nop
565 /* If we are faulting a kernel address, we have to use the
566 * kernel page tables.
567 */
568 ori r5, r0, CONFIG_KERNEL_START
569 cmpu r5, r3, r5
570 bgti r5, ex3
571 /* First, check if it was a zone fault (which means a user
572 * tried to access a kernel or read-protected page - always
573 * a SEGV). All other faults here must be stores, so no
574 * need to check ESR_S as well. */
575 andi r4, r4, 0x800 /* ESR_Z - zone protection */
576 bnei r4, ex2
578 ori r4, r0, swapper_pg_dir
579 mts rpid, r0 /* TLB will have 0 TID */
580 nop
581 bri ex4
583 /* Get the PGD for the current thread. */
584 ex3:
585 /* First, check if it was a zone fault (which means a user
586 * tried to access a kernel or read-protected page - always
587 * a SEGV). All other faults here must be stores, so no
588 * need to check ESR_S as well. */
589 andi r4, r4, 0x800 /* ESR_Z */
590 bnei r4, ex2
591 /* get current task address */
592 addi r4 ,CURRENT_TASK, TOPHYS(0);
593 lwi r4, r4, TASK_THREAD+PGDIR
594 ex4:
595 tophys(r4,r4)
596 BSRLI(r5,r3,20) /* Create L1 (pgdir/pmd) address */
597 andi r5, r5, 0xffc
598 /* Assume pgdir aligned on 4K boundary, no need for "andi r4,r4,0xfffff003" */
599 or r4, r4, r5
600 lwi r4, r4, 0 /* Get L1 entry */
601 andi r5, r4, 0xfffff000 /* Extract L2 (pte) base address */
602 beqi r5, ex2 /* Bail if no table */
604 tophys(r5,r5)
605 BSRLI(r6,r3,10) /* Compute PTE address */
606 andi r6, r6, 0xffc
607 andi r5, r5, 0xfffff003
608 or r5, r5, r6
609 lwi r4, r5, 0 /* Get Linux PTE */
611 andi r6, r4, _PAGE_RW /* Is it writeable? */
612 beqi r6, ex2 /* Bail if not */
614 /* Update 'changed' */
615 ori r4, r4, _PAGE_DIRTY|_PAGE_ACCESSED|_PAGE_HWWRITE
616 swi r4, r5, 0 /* Update Linux page table */
618 /* Most of the Linux PTE is ready to load into the TLB LO.
619 * We set ZSEL, where only the LS-bit determines user access.
620 * We set execute, because we don't have the granularity to
621 * properly set this at the page level (Linux problem).
622 * If shared is set, we cause a zero PID->TID load.
623 * Many of these bits are software only. Bits we don't set
624 * here we (properly should) assume have the appropriate value.
625 */
626 andni r4, r4, 0x0ce2 /* Make sure 20, 21 are zero */
627 ori r4, r4, _PAGE_HWEXEC /* make it executable */
629 /* find the TLB index that caused the fault. It has to be here*/
630 mts rtlbsx, r3
631 nop
632 mfs r5, rtlbx /* DEBUG: TBD */
633 nop
634 mts rtlblo, r4 /* Load TLB LO */
635 nop
636 /* Will sync shadow TLBs */
638 /* Done...restore registers and get out of here. */
639 mts rpid, r11
640 nop
641 bri 4
643 RESTORE_STATE;
644 rted r17, 0
645 nop
646 ex2:
647 /* The bailout. Restore registers to pre-exception conditions
648 * and call the heavyweights to help us out. */
649 mts rpid, r11
650 nop
651 bri 4
652 RESTORE_STATE;
653 bri page_fault_data_trap
656 /* 0x11 - Instruction Storage Exception
657 * This is caused by a fetch from non-execute or guarded pages. */
658 handle_instruction_storage_exception:
659 /* Working registers already saved: R3, R4, R5, R6
660 * R3 = ESR
661 */
663 RESTORE_STATE;
664 bri page_fault_instr_trap
666 /* 0x12 - Data TLB Miss Exception
667 * As the name implies, translation is not in the MMU, so search the
668 * page tables and fix it. The only purpose of this function is to
669 * load TLB entries from the page table if they exist.
670 */
671 handle_data_tlb_miss_exception:
672 /* Working registers already saved: R3, R4, R5, R6
673 * R3 = EAR, R4 = ESR
674 */
675 mfs r11, rpid
676 nop
678 /* If we are faulting a kernel address, we have to use the
679 * kernel page tables. */
680 ori r6, r0, CONFIG_KERNEL_START
681 cmpu r4, r3, r6
682 bgti r4, ex5
683 ori r4, r0, swapper_pg_dir
684 mts rpid, r0 /* TLB will have 0 TID */
685 nop
686 bri ex6
688 /* Get the PGD for the current thread. */
689 ex5:
690 /* get current task address */
691 addi r4 ,CURRENT_TASK, TOPHYS(0);
692 lwi r4, r4, TASK_THREAD+PGDIR
693 ex6:
694 tophys(r4,r4)
695 BSRLI(r5,r3,20) /* Create L1 (pgdir/pmd) address */
696 andi r5, r5, 0xffc
697 /* Assume pgdir aligned on 4K boundary, no need for "andi r4,r4,0xfffff003" */
698 or r4, r4, r5
699 lwi r4, r4, 0 /* Get L1 entry */
700 andi r5, r4, 0xfffff000 /* Extract L2 (pte) base address */
701 beqi r5, ex7 /* Bail if no table */
703 tophys(r5,r5)
704 BSRLI(r6,r3,10) /* Compute PTE address */
705 andi r6, r6, 0xffc
706 andi r5, r5, 0xfffff003
707 or r5, r5, r6
708 lwi r4, r5, 0 /* Get Linux PTE */
710 andi r6, r4, _PAGE_PRESENT
711 beqi r6, ex7
713 ori r4, r4, _PAGE_ACCESSED
714 swi r4, r5, 0
716 /* Most of the Linux PTE is ready to load into the TLB LO.
717 * We set ZSEL, where only the LS-bit determines user access.
718 * We set execute, because we don't have the granularity to
719 * properly set this at the page level (Linux problem).
720 * If shared is set, we cause a zero PID->TID load.
721 * Many of these bits are software only. Bits we don't set
722 * here we (properly should) assume have the appropriate value.
723 */
724 brid finish_tlb_load
725 andni r4, r4, 0x0ce2 /* Make sure 20, 21 are zero */
726 ex7:
727 /* The bailout. Restore registers to pre-exception conditions
728 * and call the heavyweights to help us out.
729 */
730 mts rpid, r11
731 nop
732 bri 4
733 RESTORE_STATE;
734 bri page_fault_data_trap
736 /* 0x13 - Instruction TLB Miss Exception
737 * Nearly the same as above, except we get our information from
738 * different registers and bailout to a different point.
739 */
740 handle_instruction_tlb_miss_exception:
741 /* Working registers already saved: R3, R4, R5, R6
742 * R3 = ESR
743 */
744 mfs r11, rpid
745 nop
747 /* If we are faulting a kernel address, we have to use the
748 * kernel page tables.
749 */
750 ori r4, r0, CONFIG_KERNEL_START
751 cmpu r4, r3, r4
752 bgti r4, ex8
753 ori r4, r0, swapper_pg_dir
754 mts rpid, r0 /* TLB will have 0 TID */
755 nop
756 bri ex9
758 /* Get the PGD for the current thread. */
759 ex8:
760 /* get current task address */
761 addi r4 ,CURRENT_TASK, TOPHYS(0);
762 lwi r4, r4, TASK_THREAD+PGDIR
763 ex9:
764 tophys(r4,r4)
765 BSRLI(r5,r3,20) /* Create L1 (pgdir/pmd) address */
766 andi r5, r5, 0xffc
767 /* Assume pgdir aligned on 4K boundary, no need for "andi r4,r4,0xfffff003" */
768 or r4, r4, r5
769 lwi r4, r4, 0 /* Get L1 entry */
770 andi r5, r4, 0xfffff000 /* Extract L2 (pte) base address */
771 beqi r5, ex10 /* Bail if no table */
773 tophys(r5,r5)
774 BSRLI(r6,r3,10) /* Compute PTE address */
775 andi r6, r6, 0xffc
776 andi r5, r5, 0xfffff003
777 or r5, r5, r6
778 lwi r4, r5, 0 /* Get Linux PTE */
780 andi r6, r4, _PAGE_PRESENT
781 beqi r6, ex10
783 ori r4, r4, _PAGE_ACCESSED
784 swi r4, r5, 0
786 /* Most of the Linux PTE is ready to load into the TLB LO.
787 * We set ZSEL, where only the LS-bit determines user access.
788 * We set execute, because we don't have the granularity to
789 * properly set this at the page level (Linux problem).
790 * If shared is set, we cause a zero PID->TID load.
791 * Many of these bits are software only. Bits we don't set
792 * here we (properly should) assume have the appropriate value.
793 */
794 brid finish_tlb_load
795 andni r4, r4, 0x0ce2 /* Make sure 20, 21 are zero */
796 ex10:
797 /* The bailout. Restore registers to pre-exception conditions
798 * and call the heavyweights to help us out.
799 */
800 mts rpid, r11
801 nop
802 bri 4
803 RESTORE_STATE;
804 bri page_fault_instr_trap
806 /* Both the instruction and data TLB miss get to this point to load the TLB.
807 * r3 - EA of fault
808 * r4 - TLB LO (info from Linux PTE)
809 * r5, r6 - available to use
810 * PID - loaded with proper value when we get here
811 * Upon exit, we reload everything and RFI.
812 * A common place to load the TLB.
813 */
814 tlb_index:
815 .long 1 /* MS: storing last used tlb index */
816 finish_tlb_load:
817 /* MS: load the last used TLB index. */
818 lwi r5, r0, TOPHYS(tlb_index)
819 addik r5, r5, 1 /* MS: inc tlb_index -> use next one */
821 /* MS: FIXME this is potential fault, because this is mask not count */
822 andi r5, r5, (MICROBLAZE_TLB_SIZE-1)
823 ori r6, r0, 1
824 cmp r31, r5, r6
825 blti r31, ex12
826 addik r5, r6, 1
827 ex12:
828 /* MS: save back current TLB index */
829 swi r5, r0, TOPHYS(tlb_index)
831 ori r4, r4, _PAGE_HWEXEC /* make it executable */
832 mts rtlbx, r5 /* MS: save current TLB */
833 nop
834 mts rtlblo, r4 /* MS: save to TLB LO */
835 nop
837 /* Create EPN. This is the faulting address plus a static
838 * set of bits. These are size, valid, E, U0, and ensure
839 * bits 20 and 21 are zero.
840 */
841 andi r3, r3, 0xfffff000
842 ori r3, r3, 0x0c0
843 mts rtlbhi, r3 /* Load TLB HI */
844 nop
846 /* Done...restore registers and get out of here. */
847 mts rpid, r11
848 nop
849 bri 4
850 RESTORE_STATE;
851 rted r17, 0
852 nop
854 /* extern void giveup_fpu(struct task_struct *prev)
855 *
856 * The MicroBlaze processor may have an FPU, so this should not just
857 * return: TBD.
858 */
859 .globl giveup_fpu;
860 .align 4;
861 giveup_fpu:
862 bralid r15,0 /* TBD */
863 nop
865 /* At present, this routine just hangs. - extern void abort(void) */
866 .globl abort;
867 .align 4;
868 abort:
869 br r0
871 .globl set_context;
872 .align 4;
873 set_context:
874 mts rpid, r5 /* Shadow TLBs are automatically */
875 nop
876 bri 4 /* flushed by changing PID */
877 rtsd r15,8
878 nop
880 #endif
881 .end _hw_exception_handler
883 #ifdef CONFIG_MMU
884 /* Unaligned data access exception last on a 4k page for MMU.
885 * When this is called, we are in virtual mode with exceptions enabled
886 * and registers 1-13,15,17,18 saved.
887 *
888 * R3 = ESR
889 * R4 = EAR
890 * R7 = pointer to saved registers (struct pt_regs *regs)
891 *
892 * This handler perform the access, and returns via ret_from_exc.
893 */
894 .global _unaligned_data_exception
895 .ent _unaligned_data_exception
896 _unaligned_data_exception:
897 andi r8, r3, 0x3E0; /* Mask and extract the register operand */
898 BSRLI(r8,r8,2); /* r8 >> 2 = register operand * 8 */
899 andi r6, r3, 0x400; /* Extract ESR[S] */
900 bneid r6, ex_sw_vm;
901 andi r6, r3, 0x800; /* Extract ESR[W] - delay slot */
902 ex_lw_vm:
903 beqid r6, ex_lhw_vm;
904 load1: lbui r5, r4, 0; /* Exception address in r4 - delay slot */
905 /* Load a word, byte-by-byte from destination address and save it in tmp space*/
906 la r6, r0, ex_tmp_data_loc_0;
907 sbi r5, r6, 0;
908 load2: lbui r5, r4, 1;
909 sbi r5, r6, 1;
910 load3: lbui r5, r4, 2;
911 sbi r5, r6, 2;
912 load4: lbui r5, r4, 3;
913 sbi r5, r6, 3;
914 brid ex_lw_tail_vm;
915 /* Get the destination register value into r3 - delay slot */
916 lwi r3, r6, 0;
917 ex_lhw_vm:
918 /* Load a half-word, byte-by-byte from destination address and
919 * save it in tmp space */
920 la r6, r0, ex_tmp_data_loc_0;
921 sbi r5, r6, 0;
922 load5: lbui r5, r4, 1;
923 sbi r5, r6, 1;
924 lhui r3, r6, 0; /* Get the destination register value into r3 */
925 ex_lw_tail_vm:
926 /* Form load_word jump table offset (lw_table_vm + (8 * regnum)) */
927 addik r5, r8, lw_table_vm;
928 bra r5;
929 ex_lw_end_vm: /* Exception handling of load word, ends */
930 brai ret_from_exc;
931 ex_sw_vm:
932 /* Form store_word jump table offset (sw_table_vm + (8 * regnum)) */
933 addik r5, r8, sw_table_vm;
934 bra r5;
935 ex_sw_tail_vm:
936 la r5, r0, ex_tmp_data_loc_0;
937 beqid r6, ex_shw_vm;
938 swi r3, r5, 0; /* Get the word - delay slot */
939 /* Store the word, byte-by-byte into destination address */
940 lbui r3, r5, 0;
941 store1: sbi r3, r4, 0;
942 lbui r3, r5, 1;
943 store2: sbi r3, r4, 1;
944 lbui r3, r5, 2;
945 store3: sbi r3, r4, 2;
946 lbui r3, r5, 3;
947 brid ret_from_exc;
948 store4: sbi r3, r4, 3; /* Delay slot */
949 ex_shw_vm:
950 /* Store the lower half-word, byte-by-byte into destination address */
951 lbui r3, r5, 2;
952 store5: sbi r3, r4, 0;
953 lbui r3, r5, 3;
954 brid ret_from_exc;
955 store6: sbi r3, r4, 1; /* Delay slot */
956 ex_sw_end_vm: /* Exception handling of store word, ends. */
958 /* We have to prevent cases that get/put_user macros get unaligned pointer
959 * to bad page area. We have to find out which origin instruction caused it
960 * and called fixup for that origin instruction not instruction in unaligned
961 * handler */
962 ex_unaligned_fixup:
963 ori r5, r7, 0 /* setup pointer to pt_regs */
964 lwi r6, r7, PT_PC; /* faulting address is one instruction above */
965 addik r6, r6, -4 /* for finding proper fixup */
966 swi r6, r7, PT_PC; /* a save back it to PT_PC */
967 addik r7, r0, SIGSEGV
968 /* call bad_page_fault for finding aligned fixup, fixup address is saved
969 * in PT_PC which is used as return address from exception */
970 la r15, r0, ret_from_exc-8 /* setup return address */
971 brid bad_page_fault
972 nop
974 /* We prevent all load/store because it could failed any attempt to access */
975 .section __ex_table,"a";
976 .word load1,ex_unaligned_fixup;
977 .word load2,ex_unaligned_fixup;
978 .word load3,ex_unaligned_fixup;
979 .word load4,ex_unaligned_fixup;
980 .word load5,ex_unaligned_fixup;
981 .word store1,ex_unaligned_fixup;
982 .word store2,ex_unaligned_fixup;
983 .word store3,ex_unaligned_fixup;
984 .word store4,ex_unaligned_fixup;
985 .word store5,ex_unaligned_fixup;
986 .word store6,ex_unaligned_fixup;
987 .previous;
988 .end _unaligned_data_exception
989 #endif /* CONFIG_MMU */
991 ex_handler_unhandled:
992 /* FIXME add handle function for unhandled exception - dump register */
993 bri 0
995 /*
996 * hw_exception_handler Jump Table
997 * - Contains code snippets for each register that caused the unalign exception
998 * - Hence exception handler is NOT self-modifying
999 * - Separate table for load exceptions and store exceptions.
1000 * - Each table is of size: (8 * 32) = 256 bytes
1001 */
1003 .section .text
1004 .align 4
1005 lw_table:
1006 lw_r0: R3_TO_LWREG (0);
1007 lw_r1: LWREG_NOP;
1008 lw_r2: R3_TO_LWREG (2);
1009 lw_r3: R3_TO_LWREG_V (3);
1010 lw_r4: R3_TO_LWREG_V (4);
1011 lw_r5: R3_TO_LWREG_V (5);
1012 lw_r6: R3_TO_LWREG_V (6);
1013 lw_r7: R3_TO_LWREG (7);
1014 lw_r8: R3_TO_LWREG (8);
1015 lw_r9: R3_TO_LWREG (9);
1016 lw_r10: R3_TO_LWREG (10);
1017 lw_r11: R3_TO_LWREG (11);
1018 lw_r12: R3_TO_LWREG (12);
1019 lw_r13: R3_TO_LWREG (13);
1020 lw_r14: R3_TO_LWREG (14);
1021 lw_r15: R3_TO_LWREG (15);
1022 lw_r16: R3_TO_LWREG (16);
1023 lw_r17: LWREG_NOP;
1024 lw_r18: R3_TO_LWREG (18);
1025 lw_r19: R3_TO_LWREG (19);
1026 lw_r20: R3_TO_LWREG (20);
1027 lw_r21: R3_TO_LWREG (21);
1028 lw_r22: R3_TO_LWREG (22);
1029 lw_r23: R3_TO_LWREG (23);
1030 lw_r24: R3_TO_LWREG (24);
1031 lw_r25: R3_TO_LWREG (25);
1032 lw_r26: R3_TO_LWREG (26);
1033 lw_r27: R3_TO_LWREG (27);
1034 lw_r28: R3_TO_LWREG (28);
1035 lw_r29: R3_TO_LWREG (29);
1036 lw_r30: R3_TO_LWREG (30);
1037 #ifdef CONFIG_MMU
1038 lw_r31: R3_TO_LWREG_V (31);
1039 #else
1040 lw_r31: R3_TO_LWREG (31);
1041 #endif
1043 sw_table:
1044 sw_r0: SWREG_TO_R3 (0);
1045 sw_r1: SWREG_NOP;
1046 sw_r2: SWREG_TO_R3 (2);
1047 sw_r3: SWREG_TO_R3_V (3);
1048 sw_r4: SWREG_TO_R3_V (4);
1049 sw_r5: SWREG_TO_R3_V (5);
1050 sw_r6: SWREG_TO_R3_V (6);
1051 sw_r7: SWREG_TO_R3 (7);
1052 sw_r8: SWREG_TO_R3 (8);
1053 sw_r9: SWREG_TO_R3 (9);
1054 sw_r10: SWREG_TO_R3 (10);
1055 sw_r11: SWREG_TO_R3 (11);
1056 sw_r12: SWREG_TO_R3 (12);
1057 sw_r13: SWREG_TO_R3 (13);
1058 sw_r14: SWREG_TO_R3 (14);
1059 sw_r15: SWREG_TO_R3 (15);
1060 sw_r16: SWREG_TO_R3 (16);
1061 sw_r17: SWREG_NOP;
1062 sw_r18: SWREG_TO_R3 (18);
1063 sw_r19: SWREG_TO_R3 (19);
1064 sw_r20: SWREG_TO_R3 (20);
1065 sw_r21: SWREG_TO_R3 (21);
1066 sw_r22: SWREG_TO_R3 (22);
1067 sw_r23: SWREG_TO_R3 (23);
1068 sw_r24: SWREG_TO_R3 (24);
1069 sw_r25: SWREG_TO_R3 (25);
1070 sw_r26: SWREG_TO_R3 (26);
1071 sw_r27: SWREG_TO_R3 (27);
1072 sw_r28: SWREG_TO_R3 (28);
1073 sw_r29: SWREG_TO_R3 (29);
1074 sw_r30: SWREG_TO_R3 (30);
1075 #ifdef CONFIG_MMU
1076 sw_r31: SWREG_TO_R3_V (31);
1077 #else
1078 sw_r31: SWREG_TO_R3 (31);
1079 #endif
1081 #ifdef CONFIG_MMU
1082 lw_table_vm:
1083 lw_r0_vm: R3_TO_LWREG_VM (0);
1084 lw_r1_vm: R3_TO_LWREG_VM_V (1);
1085 lw_r2_vm: R3_TO_LWREG_VM_V (2);
1086 lw_r3_vm: R3_TO_LWREG_VM_V (3);
1087 lw_r4_vm: R3_TO_LWREG_VM_V (4);
1088 lw_r5_vm: R3_TO_LWREG_VM_V (5);
1089 lw_r6_vm: R3_TO_LWREG_VM_V (6);
1090 lw_r7_vm: R3_TO_LWREG_VM_V (7);
1091 lw_r8_vm: R3_TO_LWREG_VM_V (8);
1092 lw_r9_vm: R3_TO_LWREG_VM_V (9);
1093 lw_r10_vm: R3_TO_LWREG_VM_V (10);
1094 lw_r11_vm: R3_TO_LWREG_VM_V (11);
1095 lw_r12_vm: R3_TO_LWREG_VM_V (12);
1096 lw_r13_vm: R3_TO_LWREG_VM_V (13);
1097 lw_r14_vm: R3_TO_LWREG_VM (14);
1098 lw_r15_vm: R3_TO_LWREG_VM_V (15);
1099 lw_r16_vm: R3_TO_LWREG_VM (16);
1100 lw_r17_vm: R3_TO_LWREG_VM_V (17);
1101 lw_r18_vm: R3_TO_LWREG_VM_V (18);
1102 lw_r19_vm: R3_TO_LWREG_VM (19);
1103 lw_r20_vm: R3_TO_LWREG_VM (20);
1104 lw_r21_vm: R3_TO_LWREG_VM (21);
1105 lw_r22_vm: R3_TO_LWREG_VM (22);
1106 lw_r23_vm: R3_TO_LWREG_VM (23);
1107 lw_r24_vm: R3_TO_LWREG_VM (24);
1108 lw_r25_vm: R3_TO_LWREG_VM (25);
1109 lw_r26_vm: R3_TO_LWREG_VM (26);
1110 lw_r27_vm: R3_TO_LWREG_VM (27);
1111 lw_r28_vm: R3_TO_LWREG_VM (28);
1112 lw_r29_vm: R3_TO_LWREG_VM (29);
1113 lw_r30_vm: R3_TO_LWREG_VM (30);
1114 lw_r31_vm: R3_TO_LWREG_VM_V (31);
1116 sw_table_vm:
1117 sw_r0_vm: SWREG_TO_R3_VM (0);
1118 sw_r1_vm: SWREG_TO_R3_VM_V (1);
1119 sw_r2_vm: SWREG_TO_R3_VM_V (2);
1120 sw_r3_vm: SWREG_TO_R3_VM_V (3);
1121 sw_r4_vm: SWREG_TO_R3_VM_V (4);
1122 sw_r5_vm: SWREG_TO_R3_VM_V (5);
1123 sw_r6_vm: SWREG_TO_R3_VM_V (6);
1124 sw_r7_vm: SWREG_TO_R3_VM_V (7);
1125 sw_r8_vm: SWREG_TO_R3_VM_V (8);
1126 sw_r9_vm: SWREG_TO_R3_VM_V (9);
1127 sw_r10_vm: SWREG_TO_R3_VM_V (10);
1128 sw_r11_vm: SWREG_TO_R3_VM_V (11);
1129 sw_r12_vm: SWREG_TO_R3_VM_V (12);
1130 sw_r13_vm: SWREG_TO_R3_VM_V (13);
1131 sw_r14_vm: SWREG_TO_R3_VM (14);
1132 sw_r15_vm: SWREG_TO_R3_VM_V (15);
1133 sw_r16_vm: SWREG_TO_R3_VM (16);
1134 sw_r17_vm: SWREG_TO_R3_VM_V (17);
1135 sw_r18_vm: SWREG_TO_R3_VM_V (18);
1136 sw_r19_vm: SWREG_TO_R3_VM (19);
1137 sw_r20_vm: SWREG_TO_R3_VM (20);
1138 sw_r21_vm: SWREG_TO_R3_VM (21);
1139 sw_r22_vm: SWREG_TO_R3_VM (22);
1140 sw_r23_vm: SWREG_TO_R3_VM (23);
1141 sw_r24_vm: SWREG_TO_R3_VM (24);
1142 sw_r25_vm: SWREG_TO_R3_VM (25);
1143 sw_r26_vm: SWREG_TO_R3_VM (26);
1144 sw_r27_vm: SWREG_TO_R3_VM (27);
1145 sw_r28_vm: SWREG_TO_R3_VM (28);
1146 sw_r29_vm: SWREG_TO_R3_VM (29);
1147 sw_r30_vm: SWREG_TO_R3_VM (30);
1148 sw_r31_vm: SWREG_TO_R3_VM_V (31);
1149 #endif /* CONFIG_MMU */
1151 /* Temporary data structures used in the handler */
1152 .section .data
1153 .align 4
1154 ex_tmp_data_loc_0:
1155 .byte 0
1156 ex_tmp_data_loc_1:
1157 .byte 0
1158 ex_tmp_data_loc_2:
1159 .byte 0
1160 ex_tmp_data_loc_3:
1161 .byte 0
1162 ex_reg_op:
1163 .byte 0