| blob | a231dd88d0e13fb514eeb92b53edf106840d10d6 |
1 /* arch/arm26/kernel/entry.S
2 *
3 * Assembled from chunks of code in arch/arm
4 *
5 * Copyright (C) 2003 Ian Molton
6 * Based on the work of RMK.
7 *
8 */
10 #include <linux/linkage.h>
12 #include <asm/assembler.h>
13 #include <asm/asm_offsets.h>
14 #include <asm/errno.h>
15 #include <asm/hardware.h>
16 #include <asm/sysirq.h>
17 #include <asm/thread_info.h>
18 #include <asm/page.h>
19 #include <asm/ptrace.h>
21 .macro zero_fp
22 #ifndef CONFIG_NO_FRAME_POINTER
23 mov fp, #0
24 #endif
25 .endm
27 .text
29 @ Bad Abort numbers
30 @ -----------------
31 @
32 #define BAD_PREFETCH 0
33 #define BAD_DATA 1
34 #define BAD_ADDREXCPTN 2
35 #define BAD_IRQ 3
36 #define BAD_UNDEFINSTR 4
38 @ OS version number used in SWIs
39 @ RISC OS is 0
40 @ RISC iX is 8
41 @
42 #define OS_NUMBER 9
43 #define ARMSWI_OFFSET 0x000f0000
45 @
46 @ Stack format (ensured by USER_* and SVC_*)
47 @ PSR and PC are comined on arm26
48 @
50 #define S_OFF 8
52 #define S_OLD_R0 64
53 #define S_PC 60
54 #define S_LR 56
55 #define S_SP 52
56 #define S_IP 48
57 #define S_FP 44
58 #define S_R10 40
59 #define S_R9 36
60 #define S_R8 32
61 #define S_R7 28
62 #define S_R6 24
63 #define S_R5 20
64 #define S_R4 16
65 #define S_R3 12
66 #define S_R2 8
67 #define S_R1 4
68 #define S_R0 0
70 .macro save_user_regs
71 str r0, [sp, #-4]! @ Store SVC r0
72 str lr, [sp, #-4]! @ Store user mode PC
73 sub sp, sp, #15*4
74 stmia sp, {r0 - lr}^ @ Store the other user-mode regs
75 mov r0, r0
76 .endm
78 .macro slow_restore_user_regs
79 ldmia sp, {r0 - lr}^ @ restore the user regs not including PC
80 mov r0, r0
81 ldr lr, [sp, #15*4] @ get user PC
82 add sp, sp, #15*4+8 @ free stack
83 movs pc, lr @ return
84 .endm
86 .macro fast_restore_user_regs
87 add sp, sp, #S_OFF
88 ldmib sp, {r1 - lr}^
89 mov r0, r0
90 ldr lr, [sp, #15*4]
91 add sp, sp, #15*4+8
92 movs pc, lr
93 .endm
95 .macro save_svc_regs
96 str sp, [sp, #-16]!
97 str lr, [sp, #8]
98 str lr, [sp, #4]
99 stmfd sp!, {r0 - r12}
100 mov r0, #-1
101 str r0, [sp, #S_OLD_R0]
102 zero_fp
103 .endm
105 .macro save_svc_regs_irq
106 str sp, [sp, #-16]!
107 str lr, [sp, #4]
108 ldr lr, .LCirq
109 ldr lr, [lr]
110 str lr, [sp, #8]
111 stmfd sp!, {r0 - r12}
112 mov r0, #-1
113 str r0, [sp, #S_OLD_R0]
114 zero_fp
115 .endm
117 .macro restore_svc_regs
118 ldmfd sp, {r0 - pc}^
119 .endm
121 .macro mask_pc, rd, rm
122 bic \rd, \rm, #PCMASK
123 .endm
125 .macro disable_irqs, temp
126 mov \temp, pc
127 orr \temp, \temp, #PSR_I_BIT
128 teqp \temp, #0
129 .endm
131 .macro enable_irqs, temp
132 mov \temp, pc
133 and \temp, \temp, #~PSR_I_BIT
134 teqp \temp, #0
135 .endm
137 .macro initialise_traps_extra
138 .endm
140 .macro get_thread_info, rd
141 mov \rd, sp, lsr #13
142 mov \rd, \rd, lsl #13
143 .endm
145 /*
146 * These are the registers used in the syscall handler, and allow us to
147 * have in theory up to 7 arguments to a function - r0 to r6.
148 *
149 * Note that tbl == why is intentional.
150 *
151 * We must set at least "tsk" and "why" when calling ret_with_reschedule.
152 */
153 scno .req r7 @ syscall number
154 tbl .req r8 @ syscall table pointer
155 why .req r8 @ Linux syscall (!= 0)
156 tsk .req r9 @ current thread_info
158 /*
159 * Get the system call number.
160 */
161 .macro get_scno
162 mask_pc lr, lr
163 ldr scno, [lr, #-4] @ get SWI instruction
164 .endm
165 /*
166 * -----------------------------------------------------------------------
167 */
169 /*
170 * We rely on the fact that R0 is at the bottom of the stack (due to
171 * slow/fast restore user regs).
172 */
173 #if S_R0 != 0
174 #error "Please fix"
175 #endif
177 /*
178 * This is the fast syscall return path. We do as little as
179 * possible here, and this includes saving r0 back into the SVC
180 * stack.
181 */
182 ret_fast_syscall:
183 disable_irqs r1 @ disable interrupts
184 ldr r1, [tsk, #TI_FLAGS]
185 tst r1, #_TIF_WORK_MASK
186 bne fast_work_pending
187 fast_restore_user_regs
189 /*
190 * Ok, we need to do extra processing, enter the slow path.
191 */
192 fast_work_pending:
193 str r0, [sp, #S_R0+S_OFF]! @ returned r0
194 work_pending:
195 tst r1, #_TIF_NEED_RESCHED
196 bne work_resched
197 tst r1, #_TIF_NOTIFY_RESUME | _TIF_SIGPENDING
198 beq no_work_pending
199 mov r0, sp @ 'regs'
200 mov r2, why @ 'syscall'
201 bl do_notify_resume
202 disable_irqs r1 @ disable interrupts
203 b no_work_pending
205 work_resched:
206 bl schedule
207 /*
208 * "slow" syscall return path. "why" tells us if this was a real syscall.
209 */
210 ENTRY(ret_to_user)
211 ret_slow_syscall:
212 disable_irqs r1 @ disable interrupts
213 ldr r1, [tsk, #TI_FLAGS]
214 tst r1, #_TIF_WORK_MASK
215 bne work_pending
216 no_work_pending:
217 slow_restore_user_regs
219 /*
220 * This is how we return from a fork.
221 */
222 ENTRY(ret_from_fork)
223 bl schedule_tail
224 get_thread_info tsk
225 ldr r1, [tsk, #TI_FLAGS] @ check for syscall tracing
226 mov why, #1
227 tst r1, #_TIF_SYSCALL_TRACE @ are we tracing syscalls?
228 beq ret_slow_syscall
229 mov r1, sp
230 mov r0, #1 @ trace exit [IP = 1]
231 bl syscall_trace
232 b ret_slow_syscall
234 // FIXME - is this strictly necessary?
235 #include "calls.S"
237 /*=============================================================================
238 * SWI handler
239 *-----------------------------------------------------------------------------
240 */
242 .align 5
243 ENTRY(vector_swi)
244 save_user_regs
245 zero_fp
246 get_scno
248 #ifdef CONFIG_ALIGNMENT_TRAP
249 ldr ip, __cr_alignment
250 ldr ip, [ip]
251 mcr p15, 0, ip, c1, c0 @ update control register
252 #endif
253 enable_irqs ip
255 str r4, [sp, #-S_OFF]! @ push fifth arg
257 get_thread_info tsk
258 ldr ip, [tsk, #TI_FLAGS] @ check for syscall tracing
259 bic scno, scno, #0xff000000 @ mask off SWI op-code
260 eor scno, scno, #OS_NUMBER << 20 @ check OS number
261 adr tbl, sys_call_table @ load syscall table pointer
262 tst ip, #_TIF_SYSCALL_TRACE @ are we tracing syscalls?
263 bne __sys_trace
265 adral lr, ret_fast_syscall @ set return address
266 orral lr, lr, #PSR_I_BIT | MODE_SVC26 @ Force SVC mode on return
267 cmp scno, #NR_syscalls @ check upper syscall limit
268 ldrcc pc, [tbl, scno, lsl #2] @ call sys_* routine
270 add r1, sp, #S_OFF
271 2: mov why, #0 @ no longer a real syscall
272 cmp scno, #ARMSWI_OFFSET
273 eor r0, scno, #OS_NUMBER << 20 @ put OS number back
274 bcs arm_syscall
275 b sys_ni_syscall @ not private func
277 /*
278 * This is the really slow path. We're going to be doing
279 * context switches, and waiting for our parent to respond.
280 */
281 __sys_trace:
282 add r1, sp, #S_OFF
283 mov r0, #0 @ trace entry [IP = 0]
284 bl syscall_trace
286 adral lr, __sys_trace_return @ set return address
287 orral lr, lr, #PSR_I_BIT | MODE_SVC26 @ Force SVC mode on return
288 add r1, sp, #S_R0 + S_OFF @ pointer to regs
289 cmp scno, #NR_syscalls @ check upper syscall limit
290 ldmccia r1, {r0 - r3} @ have to reload r0 - r3
291 ldrcc pc, [tbl, scno, lsl #2] @ call sys_* routine
292 b 2b
294 __sys_trace_return:
295 str r0, [sp, #S_R0 + S_OFF]! @ save returned r0
296 mov r1, sp
297 mov r0, #1 @ trace exit [IP = 1]
298 bl syscall_trace
299 b ret_slow_syscall
301 .align 5
302 #ifdef CONFIG_ALIGNMENT_TRAP
303 .type __cr_alignment, #object
304 __cr_alignment:
305 .word cr_alignment
306 #endif
308 .type sys_call_table, #object
309 ENTRY(sys_call_table)
310 #include "calls.S"
312 /*============================================================================
313 * Special system call wrappers
314 */
315 @ r0 = syscall number
316 @ r5 = syscall table
317 .type sys_syscall, #function
318 sys_syscall:
319 eor scno, r0, #OS_NUMBER << 20
320 cmp scno, #NR_syscalls @ check range
321 stmleia sp, {r5, r6} @ shuffle args
322 movle r0, r1
323 movle r1, r2
324 movle r2, r3
325 movle r3, r4
326 ldrle pc, [tbl, scno, lsl #2]
327 b sys_ni_syscall
329 sys_fork_wrapper:
330 add r0, sp, #S_OFF
331 b sys_fork
333 sys_vfork_wrapper:
334 add r0, sp, #S_OFF
335 b sys_vfork
337 sys_execve_wrapper:
338 add r3, sp, #S_OFF
339 b sys_execve
341 sys_clone_wapper:
342 add r2, sp, #S_OFF
343 b sys_clone
345 sys_sigsuspend_wrapper:
346 add r3, sp, #S_OFF
347 b sys_sigsuspend
349 sys_rt_sigsuspend_wrapper:
350 add r2, sp, #S_OFF
351 b sys_rt_sigsuspend
353 sys_sigreturn_wrapper:
354 add r0, sp, #S_OFF
355 b sys_sigreturn
357 sys_rt_sigreturn_wrapper:
358 add r0, sp, #S_OFF
359 b sys_rt_sigreturn
361 sys_sigaltstack_wrapper:
362 ldr r2, [sp, #S_OFF + S_SP]
363 b do_sigaltstack
365 /*
366 * Note: off_4k (r5) is always units of 4K. If we can't do the requested
367 * offset, we return EINVAL. FIXME - this lost some stuff from arm32 to
368 * ifdefs. check it out.
369 */
370 sys_mmap2:
371 tst r5, #((1 << (PAGE_SHIFT - 12)) - 1)
372 moveq r5, r5, lsr #PAGE_SHIFT - 12
373 streq r5, [sp, #4]
374 beq do_mmap2
375 mov r0, #-EINVAL
376 RETINSTR(mov,pc, lr)
378 /*
379 * Design issues:
380 * - We have several modes that each vector can be called from,
381 * each with its own set of registers. On entry to any vector,
382 * we *must* save the registers used in *that* mode.
383 *
384 * - This code must be as fast as possible.
385 *
386 * There are a few restrictions on the vectors:
387 * - the SWI vector cannot be called from *any* non-user mode
388 *
389 * - the FP emulator is *never* called from *any* non-user mode undefined
390 * instruction.
391 *
392 */
394 .text
396 .macro handle_irq
397 1: mov r4, #IOC_BASE
398 ldrb r6, [r4, #0x24] @ get high priority first
399 adr r5, irq_prio_h
400 teq r6, #0
401 ldreqb r6, [r4, #0x14] @ get low priority
402 adreq r5, irq_prio_l
404 teq r6, #0 @ If an IRQ happened...
405 ldrneb r0, [r5, r6] @ get IRQ number
406 movne r1, sp @ get struct pt_regs
407 adrne lr, 1b @ Set return address to 1b
408 orrne lr, lr, #PSR_I_BIT | MODE_SVC26 @ (and force SVC mode)
409 bne asm_do_IRQ @ process IRQ (if asserted)
410 .endm
413 /*
414 * Interrupt table (incorporates priority)
415 */
416 .macro irq_prio_table
417 irq_prio_l: .byte 0, 0, 1, 0, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3
418 .byte 4, 0, 1, 0, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3
419 .byte 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5
420 .byte 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5
421 .byte 6, 6, 6, 6, 6, 6, 6, 6, 3, 3, 3, 3, 3, 3, 3, 3
422 .byte 6, 6, 6, 6, 6, 6, 6, 6, 3, 3, 3, 3, 3, 3, 3, 3
423 .byte 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5
424 .byte 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5
425 .byte 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7
426 .byte 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7
427 .byte 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7
428 .byte 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7
429 .byte 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7
430 .byte 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7
431 .byte 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7
432 .byte 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7
433 irq_prio_h: .byte 0, 8, 9, 8,10,10,10,10,11,11,11,11,10,10,10,10
434 .byte 12, 8, 9, 8,10,10,10,10,11,11,11,11,10,10,10,10
435 .byte 13,13,13,13,10,10,10,10,11,11,11,11,10,10,10,10
436 .byte 13,13,13,13,10,10,10,10,11,11,11,11,10,10,10,10
437 .byte 14,14,14,14,10,10,10,10,11,11,11,11,10,10,10,10
438 .byte 14,14,14,14,10,10,10,10,11,11,11,11,10,10,10,10
439 .byte 13,13,13,13,10,10,10,10,11,11,11,11,10,10,10,10
440 .byte 13,13,13,13,10,10,10,10,11,11,11,11,10,10,10,10
441 .byte 15,15,15,15,10,10,10,10,11,11,11,11,10,10,10,10
442 .byte 15,15,15,15,10,10,10,10,11,11,11,11,10,10,10,10
443 .byte 13,13,13,13,10,10,10,10,11,11,11,11,10,10,10,10
444 .byte 13,13,13,13,10,10,10,10,11,11,11,11,10,10,10,10
445 .byte 15,15,15,15,10,10,10,10,11,11,11,11,10,10,10,10
446 .byte 15,15,15,15,10,10,10,10,11,11,11,11,10,10,10,10
447 .byte 13,13,13,13,10,10,10,10,11,11,11,11,10,10,10,10
448 .byte 13,13,13,13,10,10,10,10,11,11,11,11,10,10,10,10
449 .endm
451 #if 1
452 /*
453 * Uncomment these if you wish to get more debugging into about data aborts.
454 * FIXME - I bet we can find a way to encode these and keep performance.
455 */
456 #define FAULT_CODE_LDRSTRPOST 0x80
457 #define FAULT_CODE_LDRSTRPRE 0x40
458 #define FAULT_CODE_LDRSTRREG 0x20
459 #define FAULT_CODE_LDMSTM 0x10
460 #define FAULT_CODE_LDCSTC 0x08
461 #endif
462 #define FAULT_CODE_PREFETCH 0x04
463 #define FAULT_CODE_WRITE 0x02
464 #define FAULT_CODE_FORCECOW 0x01
466 /*=============================================================================
467 * Undefined FIQs
468 *-----------------------------------------------------------------------------
469 */
470 _unexp_fiq: ldr sp, .LCfiq
471 mov r12, #IOC_BASE
472 strb r12, [r12, #0x38] @ Disable FIQ register
473 teqp pc, #PSR_I_BIT | PSR_F_BIT | MODE_SVC26
474 mov r0, r0
475 stmfd sp!, {r0 - r3, ip, lr}
476 adr r0, Lfiqmsg
477 bl printk
478 ldmfd sp!, {r0 - r3, ip, lr}
479 teqp pc, #PSR_I_BIT | PSR_F_BIT | MODE_FIQ26
480 mov r0, r0
481 movs pc, lr
483 Lfiqmsg: .ascii "*** Unexpected FIQ\n\0"
484 .align
486 .LCfiq: .word __temp_fiq
487 .LCirq: .word __temp_irq
489 /*=============================================================================
490 * Undefined instruction handler
491 *-----------------------------------------------------------------------------
492 * Handles floating point instructions
493 */
494 vector_undefinstr:
495 tst lr, #MODE_SVC26 @ did we come from a non-user mode?
496 bne __und_svc @ yes - deal with it.
497 /* Otherwise, fall through for the user-space (common) case. */
498 save_user_regs
499 zero_fp @ zero frame pointer
500 teqp pc, #PSR_I_BIT | MODE_SVC26 @ disable IRQs
501 .Lbug_undef:
502 ldr r4, .LC2
503 ldr pc, [r4] @ Call FP module entry point
504 /* FIXME - should we trap for a null pointer here? */
506 /* The SVC mode case */
507 __und_svc: save_svc_regs @ Non-user mode
508 mask_pc r0, lr
509 and r2, lr, #3
510 sub r0, r0, #4
511 mov r1, sp
512 bl do_undefinstr
513 restore_svc_regs
515 /* We get here if the FP emulator doesnt handle the undef instr.
516 * If the insn WAS handled, the emulator jumps to ret_from_exception by itself/
517 */
518 .globl fpundefinstr
519 fpundefinstr:
520 mov r0, lr
521 mov r1, sp
522 teqp pc, #MODE_SVC26
523 bl do_undefinstr
524 b ret_from_exception @ Normal FP exit
526 #if defined CONFIG_FPE_NWFPE || defined CONFIG_FPE_FASTFPE
527 /* The FPE is always present */
528 .equ fpe_not_present, 0
529 #else
530 /* We get here if an undefined instruction happens and the floating
531 * point emulator is not present. If the offending instruction was
532 * a WFS, we just perform a normal return as if we had emulated the
533 * operation. This is a hack to allow some basic userland binaries
534 * to run so that the emulator module proper can be loaded. --philb
535 * FIXME - probably a broken useless hack...
536 */
537 fpe_not_present:
538 adr r10, wfs_mask_data
539 ldmia r10, {r4, r5, r6, r7, r8}
540 ldr r10, [sp, #S_PC] @ Load PC
541 sub r10, r10, #4
542 mask_pc r10, r10
543 ldrt r10, [r10] @ get instruction
544 and r5, r10, r5
545 teq r5, r4 @ Is it WFS?
546 beq ret_from_exception
547 and r5, r10, r8
548 teq r5, r6 @ Is it LDF/STF on sp or fp?
549 teqne r5, r7
550 bne fpundefinstr
551 tst r10, #0x00200000 @ Does it have WB
552 beq ret_from_exception
553 and r4, r10, #255 @ get offset
554 and r6, r10, #0x000f0000
555 tst r10, #0x00800000 @ +/-
556 ldr r5, [sp, r6, lsr #14] @ Load reg
557 rsbeq r4, r4, #0
558 add r5, r5, r4, lsl #2
559 str r5, [sp, r6, lsr #14] @ Save reg
560 b ret_from_exception
562 wfs_mask_data: .word 0x0e200110 @ WFS/RFS
563 .word 0x0fef0fff
564 .word 0x0d0d0100 @ LDF [sp]/STF [sp]
565 .word 0x0d0b0100 @ LDF [fp]/STF [fp]
566 .word 0x0f0f0f00
567 #endif
569 .LC2: .word fp_enter
571 /*=============================================================================
572 * Prefetch abort handler
573 *-----------------------------------------------------------------------------
574 */
575 #define DEBUG_UNDEF
576 /* remember: lr = USR pc */
577 vector_prefetch:
578 sub lr, lr, #4
579 tst lr, #MODE_SVC26
580 bne __pabt_invalid
581 save_user_regs
582 teqp pc, #MODE_SVC26 @ Enable IRQs...
583 mask_pc r0, lr @ Address of abort
584 mov r1, sp @ Tasks registers
585 bl do_PrefetchAbort
586 teq r0, #0 @ If non-zero, we believe this abort..
587 bne ret_from_exception
588 #ifdef DEBUG_UNDEF
589 adr r0, t
590 bl printk
591 #endif
592 ldr lr, [sp,#S_PC] @ FIXME program to test this on. I think its
593 b .Lbug_undef @ broken at the moment though!)
595 __pabt_invalid: save_svc_regs
596 mov r0, sp @ Prefetch aborts are definitely *not*
597 mov r1, #BAD_PREFETCH @ allowed in non-user modes. We cant
598 and r2, lr, #3 @ recover from this problem.
599 b bad_mode
601 #ifdef DEBUG_UNDEF
602 t: .ascii "*** undef ***\r\n\0"
603 .align
604 #endif
606 /*=============================================================================
607 * Address exception handler
608 *-----------------------------------------------------------------------------
609 * These aren't too critical.
610 * (they're not supposed to happen).
611 * In order to debug the reason for address exceptions in non-user modes,
612 * we have to obtain all the registers so that we can see what's going on.
613 */
615 vector_addrexcptn:
616 sub lr, lr, #8
617 tst lr, #3
618 bne Laddrexcptn_not_user
619 save_user_regs
620 teq pc, #MODE_SVC26
621 mask_pc r0, lr @ Point to instruction
622 mov r1, sp @ Point to registers
623 mov r2, #0x400
624 mov lr, pc
625 bl do_excpt
626 b ret_from_exception
628 Laddrexcptn_not_user:
629 save_svc_regs
630 and r2, lr, #3
631 teq r2, #3
632 bne Laddrexcptn_illegal_mode
633 teqp pc, #MODE_SVC26
634 mask_pc r0, lr
635 mov r1, sp
636 orr r2, r2, #0x400
637 bl do_excpt
638 ldmia sp, {r0 - lr} @ I cant remember the reason I changed this...
639 add sp, sp, #15*4
640 movs pc, lr
642 Laddrexcptn_illegal_mode:
643 mov r0, sp
644 str lr, [sp, #-4]!
645 orr r1, r2, #PSR_I_BIT | PSR_F_BIT
646 teqp r1, #0 @ change into mode (wont be user mode)
647 mov r0, r0
648 mov r1, r8 @ Any register from r8 - r14 can be banked
649 mov r2, r9
650 mov r3, r10
651 mov r4, r11
652 mov r5, r12
653 mov r6, r13
654 mov r7, r14
655 teqp pc, #PSR_F_BIT | MODE_SVC26 @ back to svc
656 mov r0, r0
657 stmfd sp!, {r1-r7}
658 ldmia r0, {r0-r7}
659 stmfd sp!, {r0-r7}
660 mov r0, sp
661 mov r1, #BAD_ADDREXCPTN
662 b bad_mode
664 /*=============================================================================
665 * Interrupt (IRQ) handler
666 *-----------------------------------------------------------------------------
667 * Note: if the IRQ was taken whilst in user mode, then *no* kernel routine
668 * is running, so do not have to save svc lr.
669 *
670 * Entered in IRQ mode.
671 */
673 vector_IRQ: ldr sp, .LCirq @ Setup some temporary stack
674 sub lr, lr, #4
675 str lr, [sp] @ push return address
677 tst lr, #3
678 bne __irq_non_usr
680 __irq_usr: teqp pc, #PSR_I_BIT | MODE_SVC26 @ Enter SVC mode
681 mov r0, r0
683 ldr lr, .LCirq
684 ldr lr, [lr] @ Restore lr for jump back to USR
686 save_user_regs
688 handle_irq
690 mov why, #0
691 get_thread_info tsk
692 b ret_to_user
694 @ Place the IRQ priority table here so that the handle_irq macros above
695 @ and below here can access it.
697 irq_prio_table
699 __irq_non_usr: teqp pc, #PSR_I_BIT | MODE_SVC26 @ Enter SVC mode
700 mov r0, r0
702 save_svc_regs_irq
704 and r2, lr, #3
705 teq r2, #3
706 bne __irq_invalid @ IRQ not from SVC mode
708 handle_irq
710 restore_svc_regs
712 __irq_invalid: mov r0, sp
713 mov r1, #BAD_IRQ
714 b bad_mode
716 /*=============================================================================
717 * Data abort handler code
718 *-----------------------------------------------------------------------------
719 *
720 * This handles both exceptions from user and SVC modes, computes the address
721 * range of the problem, and does any correction that is required. It then
722 * calls the kernel data abort routine.
723 *
724 * This is where I wish that the ARM would tell you which address aborted.
725 */
727 vector_data: sub lr, lr, #8 @ Correct lr
728 tst lr, #3
729 bne Ldata_not_user
730 save_user_regs
731 teqp pc, #MODE_SVC26
732 mask_pc r0, lr
733 bl Ldata_do
734 b ret_from_exception
736 Ldata_not_user:
737 save_svc_regs
738 and r2, lr, #3
739 teq r2, #3
740 bne Ldata_illegal_mode
741 tst lr, #PSR_I_BIT
742 teqeqp pc, #MODE_SVC26
743 mask_pc r0, lr
744 bl Ldata_do
745 restore_svc_regs
747 Ldata_illegal_mode:
748 mov r0, sp
749 mov r1, #BAD_DATA
750 b bad_mode
752 Ldata_do: mov r3, sp
753 ldr r4, [r0] @ Get instruction
754 mov r2, #0
755 tst r4, #1 << 20 @ Check to see if it is a write instruction
756 orreq r2, r2, #FAULT_CODE_WRITE @ Indicate write instruction
757 mov r1, r4, lsr #22 @ Now branch to the relevent processing routine
758 and r1, r1, #15 << 2
759 add pc, pc, r1
760 movs pc, lr
761 b Ldata_unknown
762 b Ldata_unknown
763 b Ldata_unknown
764 b Ldata_unknown
765 b Ldata_ldrstr_post @ ldr rd, [rn], #m
766 b Ldata_ldrstr_numindex @ ldr rd, [rn, #m] @ RegVal
767 b Ldata_ldrstr_post @ ldr rd, [rn], rm
768 b Ldata_ldrstr_regindex @ ldr rd, [rn, rm]
769 b Ldata_ldmstm @ ldm*a rn, <rlist>
770 b Ldata_ldmstm @ ldm*b rn, <rlist>
771 b Ldata_unknown
772 b Ldata_unknown
773 b Ldata_ldrstr_post @ ldc rd, [rn], #m @ Same as ldr rd, [rn], #m
774 b Ldata_ldcstc_pre @ ldc rd, [rn, #m]
775 b Ldata_unknown
776 Ldata_unknown: @ Part of jumptable
777 mov r0, r1
778 mov r1, r4
779 mov r2, r3
780 b baddataabort
782 Ldata_ldrstr_post:
783 mov r0, r4, lsr #14 @ Get Rn
784 and r0, r0, #15 << 2 @ Mask out reg.
785 teq r0, #15 << 2
786 ldr r0, [r3, r0] @ Get register
787 biceq r0, r0, #PCMASK
788 mov r1, r0
789 #ifdef FAULT_CODE_LDRSTRPOST
790 orr r2, r2, #FAULT_CODE_LDRSTRPOST
791 #endif
792 b do_DataAbort
794 Ldata_ldrstr_numindex:
795 mov r0, r4, lsr #14 @ Get Rn
796 and r0, r0, #15 << 2 @ Mask out reg.
797 teq r0, #15 << 2
798 ldr r0, [r3, r0] @ Get register
799 mov r1, r4, lsl #20
800 biceq r0, r0, #PCMASK
801 tst r4, #1 << 23
802 addne r0, r0, r1, lsr #20
803 subeq r0, r0, r1, lsr #20
804 mov r1, r0
805 #ifdef FAULT_CODE_LDRSTRPRE
806 orr r2, r2, #FAULT_CODE_LDRSTRPRE
807 #endif
808 b do_DataAbort
810 Ldata_ldrstr_regindex:
811 mov r0, r4, lsr #14 @ Get Rn
812 and r0, r0, #15 << 2 @ Mask out reg.
813 teq r0, #15 << 2
814 ldr r0, [r3, r0] @ Get register
815 and r7, r4, #15
816 biceq r0, r0, #PCMASK
817 teq r7, #15 @ Check for PC
818 ldr r7, [r3, r7, lsl #2] @ Get Rm
819 and r8, r4, #0x60 @ Get shift types
820 biceq r7, r7, #PCMASK
821 mov r9, r4, lsr #7 @ Get shift amount
822 and r9, r9, #31
823 teq r8, #0
824 moveq r7, r7, lsl r9
825 teq r8, #0x20 @ LSR shift
826 moveq r7, r7, lsr r9
827 teq r8, #0x40 @ ASR shift
828 moveq r7, r7, asr r9
829 teq r8, #0x60 @ ROR shift
830 moveq r7, r7, ror r9
831 tst r4, #1 << 23
832 addne r0, r0, r7
833 subeq r0, r0, r7 @ Apply correction
834 mov r1, r0
835 #ifdef FAULT_CODE_LDRSTRREG
836 orr r2, r2, #FAULT_CODE_LDRSTRREG
837 #endif
838 b do_DataAbort
840 Ldata_ldmstm:
841 mov r7, #0x11
842 orr r7, r7, r7, lsl #8
843 and r0, r4, r7
844 and r1, r4, r7, lsl #1
845 add r0, r0, r1, lsr #1
846 and r1, r4, r7, lsl #2
847 add r0, r0, r1, lsr #2
848 and r1, r4, r7, lsl #3
849 add r0, r0, r1, lsr #3
850 add r0, r0, r0, lsr #8
851 add r0, r0, r0, lsr #4
852 and r7, r0, #15 @ r7 = no. of registers to transfer.
853 mov r5, r4, lsr #14 @ Get Rn
854 and r5, r5, #15 << 2
855 ldr r0, [r3, r5] @ Get reg
856 eor r6, r4, r4, lsl #2
857 tst r6, #1 << 23 @ Check inc/dec ^ writeback
858 rsbeq r7, r7, #0
859 add r7, r0, r7, lsl #2 @ Do correction (signed)
860 subne r1, r7, #1
861 subeq r1, r0, #1
862 moveq r0, r7
863 tst r4, #1 << 21 @ Check writeback
864 strne r7, [r3, r5]
865 eor r6, r4, r4, lsl #1
866 tst r6, #1 << 24 @ Check Pre/Post ^ inc/dec
867 addeq r0, r0, #4
868 addeq r1, r1, #4
869 teq r5, #15*4 @ CHECK FOR PC
870 biceq r1, r1, #PCMASK
871 biceq r0, r0, #PCMASK
872 #ifdef FAULT_CODE_LDMSTM
873 orr r2, r2, #FAULT_CODE_LDMSTM
874 #endif
875 b do_DataAbort
877 Ldata_ldcstc_pre:
878 mov r0, r4, lsr #14 @ Get Rn
879 and r0, r0, #15 << 2 @ Mask out reg.
880 teq r0, #15 << 2
881 ldr r0, [r3, r0] @ Get register
882 mov r1, r4, lsl #24 @ Get offset
883 biceq r0, r0, #PCMASK
884 tst r4, #1 << 23
885 addne r0, r0, r1, lsr #24
886 subeq r0, r0, r1, lsr #24
887 mov r1, r0
888 #ifdef FAULT_CODE_LDCSTC
889 orr r2, r2, #FAULT_CODE_LDCSTC
890 #endif
891 b do_DataAbort
894 /*
895 * This is the return code to user mode for abort handlers
896 */
897 ENTRY(ret_from_exception)
898 get_thread_info tsk
899 mov why, #0
900 b ret_to_user
902 .data
903 ENTRY(fp_enter)
904 .word fpe_not_present
905 .text
906 /*
907 * Register switch for older 26-bit only ARMs
908 */
909 ENTRY(__switch_to)
910 add r0, r0, #TI_CPU_SAVE
911 stmia r0, {r4 - sl, fp, sp, lr}
912 add r1, r1, #TI_CPU_SAVE
913 ldmia r1, {r4 - sl, fp, sp, pc}^
915 /*
916 *=============================================================================
917 * Low-level interface code
918 *-----------------------------------------------------------------------------
919 * Trap initialisation
920 *-----------------------------------------------------------------------------
921 *
922 * Note - FIQ code has changed. The default is a couple of words in 0x1c, 0x20
923 * that call _unexp_fiq. Nowever, we now copy the FIQ routine to 0x1c (removes
924 * some excess cycles).
925 *
926 * What we need to put into 0-0x1c are branches to branch to the kernel.
927 */
929 .section ".init.text",#alloc,#execinstr
931 .Ljump_addresses:
932 swi SYS_ERROR0
933 .word vector_undefinstr - 12
934 .word vector_swi - 16
935 .word vector_prefetch - 20
936 .word vector_data - 24
937 .word vector_addrexcptn - 28
938 .word vector_IRQ - 32
939 .word _unexp_fiq - 36
940 b . + 8
941 /*
942 * initialise the trap system
943 */
944 ENTRY(__trap_init)
945 stmfd sp!, {r4 - r7, lr}
946 adr r1, .Ljump_addresses
947 ldmia r1, {r1 - r7, ip, lr}
948 orr r2, lr, r2, lsr #2
949 orr r3, lr, r3, lsr #2
950 orr r4, lr, r4, lsr #2
951 orr r5, lr, r5, lsr #2
952 orr r6, lr, r6, lsr #2
953 orr r7, lr, r7, lsr #2
954 orr ip, lr, ip, lsr #2
955 mov r0, #0
956 stmia r0, {r1 - r7, ip}
957 ldmfd sp!, {r4 - r7, pc}^
959 .bss
960 __temp_irq: .space 4 @ saved lr_irq
961 __temp_fiq: .space 128