aboutsummaryrefslogtreecommitdiffstats
path: root/arch/powerpc/kernel/entry_64.S
blob: 2b66d53dcc55fbf5f7d4d52d7ba0d3c1bbc8bc8d (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
/*
 *  PowerPC version 
 *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
 *  Rewritten by Cort Dougan (cort@cs.nmt.edu) for PReP
 *    Copyright (C) 1996 Cort Dougan <cort@cs.nmt.edu>
 *  Adapted for Power Macintosh by Paul Mackerras.
 *  Low-level exception handlers and MMU support
 *  rewritten by Paul Mackerras.
 *    Copyright (C) 1996 Paul Mackerras.
 *  MPC8xx modifications Copyright (C) 1997 Dan Malek (dmalek@jlc.net).
 *
 *  This file contains the system call entry code, context switch
 *  code, and exception/interrupt return code for PowerPC.
 *
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU General Public License
 *  as published by the Free Software Foundation; either version
 *  2 of the License, or (at your option) any later version.
 */

#include <linux/errno.h>
#include <asm/unistd.h>
#include <asm/processor.h>
#include <asm/page.h>
#include <asm/mmu.h>
#include <asm/thread_info.h>
#include <asm/ppc_asm.h>
#include <asm/asm-offsets.h>
#include <asm/cputable.h>
#include <asm/firmware.h>
#include <asm/bug.h>

/*
 * System calls.
 */
	.section	".toc","aw"
.SYS_CALL_TABLE:
	.tc .sys_call_table[TC],.sys_call_table

/* This value is used to mark exception frames on the stack. */
exception_marker:
	.tc	ID_72656773_68657265[TC],0x7265677368657265

	.section	".text"
	.align 7

#undef SHOW_SYSCALLS

	.globl system_call_common
system_call_common:
	andi.	r10,r12,MSR_PR
	mr	r10,r1
	addi	r1,r1,-INT_FRAME_SIZE
	beq-	1f
	ld	r1,PACAKSAVE(r13)
1:	std	r10,0(r1)
	crclr	so
	std	r11,_NIP(r1)
	std	r12,_MSR(r1)
	std	r0,GPR0(r1)
	std	r10,GPR1(r1)
	ACCOUNT_CPU_USER_ENTRY(r10, r11)
	std	r2,GPR2(r1)
	std	r3,GPR3(r1)
	std	r4,GPR4(r1)
	std	r5,GPR5(r1)
	std	r6,GPR6(r1)
	std	r7,GPR7(r1)
	std	r8,GPR8(r1)
	li	r11,0
	std	r11,GPR9(r1)
	std	r11,GPR10(r1)
	std	r11,GPR11(r1)
	std	r11,GPR12(r1)
	std	r9,GPR13(r1)
	mfcr	r9
	mflr	r10
	li	r11,0xc01
	std	r9,_CCR(r1)
	std	r10,_LINK(r1)
	std	r11,_TRAP(r1)
	mfxer	r9
	mfctr	r10
	std	r9,_XER(r1)
	std	r10,_CTR(r1)
	std	r3,ORIG_GPR3(r1)
	ld	r2,PACATOC(r13)
	addi	r9,r1,STACK_FRAME_OVERHEAD
	ld	r11,exception_marker@toc(r2)
	std	r11,-16(r9)		/* "regshere" marker */
	li	r10,1
	stb	r10,PACASOFTIRQEN(r13)
	stb	r10,PACAHARDIRQEN(r13)
	std	r10,SOFTE(r1)
#ifdef CONFIG_PPC_ISERIES
BEGIN_FW_FTR_SECTION
	/* Hack for handling interrupts when soft-enabling on iSeries */
	cmpdi	cr1,r0,0x5555		/* syscall 0x5555 */
	andi.	r10,r12,MSR_PR		/* from kernel */
	crand	4*cr0+eq,4*cr1+eq,4*cr0+eq
	bne	2f
	b	hardware_interrupt_entry
2:
END_FW_FTR_SECTION_IFSET(FW_FEATURE_ISERIES)
#endif
	mfmsr	r11
	ori	r11,r11,MSR_EE
	mtmsrd	r11,1

#ifdef SHOW_SYSCALLS
	bl	.do_show_syscall
	REST_GPR(0,r1)
	REST_4GPRS(3,r1)
	REST_2GPRS(7,r1)
	addi	r9,r1,STACK_FRAME_OVERHEAD
#endif
	clrrdi	r11,r1,THREAD_SHIFT
	ld	r10,TI_FLAGS(r11)
	andi.	r11,r10,_TIF_SYSCALL_T_OR_A
	bne-	syscall_dotrace
syscall_dotrace_cont:
	cmpldi	0,r0,NR_syscalls
	bge-	syscall_enosys

system_call:			/* label this so stack traces look sane */
/*
 * Need to vector to 32 Bit or default sys_call_table here,
 * based on caller's run-mode / personality.
 */
	ld	r11,.SYS_CALL_TABLE@toc(2)
	andi.	r10,r10,_TIF_32BIT
	beq	15f
	addi	r11,r11,8	/* use 32-bit syscall entries */
	clrldi	r3,r3,32
	clrldi	r4,r4,32
	clrldi	r5,r5,32
	clrldi	r6,r6,32
	clrldi	r7,r7,32
	clrldi	r8,r8,32
15:
	slwi	r0,r0,4
	ldx	r10,r11,r0	/* Fetch system call handler [ptr] */
	mtctr   r10
	bctrl			/* Call handler */

syscall_exit:
	std	r3,RESULT(r1)
#ifdef SHOW_SYSCALLS
	bl	.do_show_syscall_exit
	ld	r3,RESULT(r1)
#endif
	clrrdi	r12,r1,THREAD_SHIFT

	/* disable interrupts so current_thread_info()->flags can't change,
	   and so that we don't get interrupted after loading SRR0/1. */
	ld	r8,_MSR(r1)
	andi.	r10,r8,MSR_RI
	beq-	unrecov_restore
	mfmsr	r10
	rldicl	r10,r10,48,1
	rotldi	r10,r10,16
	mtmsrd	r10,1
	ld	r9,TI_FLAGS(r12)
	li	r11,-_LAST_ERRNO
	andi.	r0,r9,(_TIF_SYSCALL_T_OR_A|_TIF_SINGLESTEP|_TIF_USER_WORK_MASK|_TIF_PERSYSCALL_MASK)
	bne-	syscall_exit_work
	cmpld	r3,r11
	ld	r5,_CCR(r1)
	bge-	syscall_error
syscall_error_cont:
	ld	r7,_NIP(r1)
	stdcx.	r0,0,r1			/* to clear the reservation */
	andi.	r6,r8,MSR_PR
	ld	r4,_LINK(r1)
	/*
	 * Clear RI before restoring r13.  If we are returning to
	 * userspace and we take an exception after restoring r13,
	 * we end up corrupting the userspace r13 value.
	 */
	li	r12,MSR_RI
	andc	r11,r10,r12
	mtmsrd	r11,1			/* clear MSR.RI */
	beq-	1f
	ACCOUNT_CPU_USER_EXIT(r11, r12)
	ld	r13,GPR13(r1)	/* only restore r13 if returning to usermode */
1:	ld	r2,GPR2(r1)
	ld	r1,GPR1(r1)
	mtlr	r4
	mtcr	r5
	mtspr	SPRN_SRR0,r7
	mtspr	SPRN_SRR1,r8
	rfid
	b	.	/* prevent speculative execution */

syscall_error:	
	oris	r5,r5,0x1000	/* Set SO bit in CR */
	neg	r3,r3
	std	r5,_CCR(r1)
	b	syscall_error_cont
	
/* Traced system call support */
syscall_dotrace:
	bl	.save_nvgprs
	addi	r3,r1,STACK_FRAME_OVERHEAD
	bl	.do_syscall_trace_enter
	ld	r0,GPR0(r1)	/* Restore original registers */
	ld	r3,GPR3(r1)
	ld	r4,GPR4(r1)
	ld	r5,GPR5(r1)
	ld	r6,GPR6(r1)
	ld	r7,GPR7(r1)
	ld	r8,GPR8(r1)
	addi	r9,r1,STACK_FRAME_OVERHEAD
	clrrdi	r10,r1,THREAD_SHIFT
	ld	r10,TI_FLAGS(r10)
	b	syscall_dotrace_cont

syscall_enosys:
	li	r3,-ENOSYS
	b	syscall_exit
	
syscall_exit_work:
	/* If TIF_RESTOREALL is set, don't scribble on either r3 or ccr.
	 If TIF_NOERROR is set, just save r3 as it is. */

	andi.	r0,r9,_TIF_RESTOREALL
	beq+	0f
	REST_NVGPRS(r1)
	b	2f
0:	cmpld	r3,r11		/* r10 is -LAST_ERRNO */
	blt+	1f
	andi.	r0,r9,_TIF_NOERROR
	bne-	1f
	ld	r5,_CCR(r1)
	neg	r3,r3
	oris	r5,r5,0x1000	/* Set SO bit in CR */
	std	r5,_CCR(r1)
1:	std	r3,GPR3(r1)
2:	andi.	r0,r9,(_TIF_PERSYSCALL_MASK)
	beq	4f

	/* Clear per-syscall TIF flags if any are set.  */

	li	r11,_TIF_PERSYSCALL_MASK
	addi	r12,r12,TI_FLAGS
3:	ldarx	r10,0,r12
	andc	r10,r10,r11
	stdcx.	r10,0,r12
	bne-	3b
	subi	r12,r12,TI_FLAGS

4:	/* Anything else left to do? */
	andi.	r0,r9,(_TIF_SYSCALL_T_OR_A|_TIF_SINGLESTEP)
	beq	.ret_from_except_lite

	/* Re-enable interrupts */
	mfmsr	r10
	ori	r10,r10,MSR_EE
	mtmsrd	r10,1

	bl	.save_nvgprs
	addi	r3,r1,STACK_FRAME_OVERHEAD
	bl	.do_syscall_trace_leave
	b	.ret_from_except

/* Save non-volatile GPRs, if not already saved. */
_GLOBAL(save_nvgprs)
	ld	r11,_TRAP(r1)
	andi.	r0,r11,1
	beqlr-
	SAVE_NVGPRS(r1)
	clrrdi	r0,r11,1
	std	r0,_TRAP(r1)
	blr

	
/*
 * The sigsuspend and rt_sigsuspend system calls can call do_signal
 * and thus put the process into the stopped state where we might
 * want to examine its user state with ptrace.  Therefore we need
 * to save all the nonvolatile registers (r14 - r31) before calling
 * the C code.  Similarly, fork, vfork and clone need the full
 * register state on the stack so that it can be copied to the child.
 */

_GLOBAL(ppc_fork)
	bl	.save_nvgprs
	bl	.sys_fork
	b	syscall_exit

_GLOBAL(ppc_vfork)
	bl	.save_nvgprs
	bl	.sys_vfork
	b	syscall_exit

_GLOBAL(ppc_clone)
	bl	.save_nvgprs
	bl	.sys_clone
	b	syscall_exit

_GLOBAL(ppc32_swapcontext)
	bl	.save_nvgprs
	bl	.compat_sys_swapcontext
	b	syscall_exit

_GLOBAL(ppc64_swapcontext)
	bl	.save_nvgprs
	bl	.sys_swapcontext
	b	syscall_exit

_GLOBAL(ret_from_fork)
	bl	.schedule_tail
	REST_NVGPRS(r1)
	li	r3,0
	b	syscall_exit

/*
 * This routine switches between two different tasks.  The process
 * state of one is saved on its kernel stack.  Then the state
 * of the other is restored from its kernel stack.  The memory
 * management hardware is updated to the second process's state.
 * Finally, we can return to the second process, via ret_from_except.
 * On entry, r3 points to the THREAD for the current task, r4
 * points to the THREAD for the new task.
 *
 * Note: there are two ways to get to the "going out" portion
 * of this code; either by coming in via the entry (_switch)
 * or via "fork" which must set up an environment equivalent
 * to the "_switch" path.  If you change this you'll have to change
 * the fork code also.
 *
 * The code which creates the new task context is in 'copy_thread'
 * in arch/powerpc/kernel/process.c 
 */
	.align	7
_GLOBAL(_switch)
	mflr	r0
	std	r0,16(r1)
	stdu	r1,-SWITCH_FRAME_SIZE(r1)
	/* r3-r13 are caller saved -- Cort */
	SAVE_8GPRS(14, r1)
	SAVE_10GPRS(22, r1)
	mflr	r20		/* Return to switch caller */
	mfmsr	r22
	li	r0, MSR_FP
#ifdef CONFIG_ALTIVEC
BEGIN_FTR_SECTION
	oris	r0,r0,MSR_VEC@h	/* Disable altivec */
	mfspr	r24,SPRN_VRSAVE	/* save vrsave register value */
	std	r24,THREAD_VRSAVE(r3)
END_FTR_SECTION_IFSET(CPU_FTR_ALTIVEC)
#endif /* CONFIG_ALTIVEC */
	and.	r0,r0,r22
	beq+	1f
	andc	r22,r22,r0
	mtmsrd	r22
	isync
1:	std	r20,_NIP(r1)
	mfcr	r23
	std	r23,_CCR(r1)
	std	r1,KSP(r3)	/* Set old stack pointer */

#ifdef CONFIG_SMP
	/* We need a sync somewhere here to make sure that if the
	 * previous task gets rescheduled on another CPU, it sees all
	 * stores it has performed on this one.
	 */
	sync
#endif /* CONFIG_SMP */

	addi	r6,r4,-THREAD	/* Convert THREAD to 'current' */
	std	r6,PACACURRENT(r13)	/* Set new 'current' */

	ld	r8,KSP(r4)	/* new stack pointer */
BEGIN_FTR_SECTION
	clrrdi	r6,r8,28	/* get its ESID */
	clrrdi	r9,r1,28	/* get current sp ESID */
	clrldi.	r0,r6,2		/* is new ESID c00000000? */
	cmpd	cr1,r6,r9	/* or is new ESID the same as current ESID? */
	cror	eq,4*cr1+eq,eq
	beq	2f		/* if yes, don't slbie it */

	/* Bolt in the new stack SLB entry */
	ld	r7,KSP_VSID(r4)	/* Get new stack's VSID */
	oris	r0,r6,(SLB_ESID_V)@h
	ori	r0,r0,(SLB_NUM_BOLTED-1)@l

	/* Update the last bolted SLB */
	ld	r9,PACA_SLBSHADOWPTR(r13)
	li	r12,0
	std	r12,SLBSHADOW_STACKESID(r9) /* Clear ESID */
	std	r7,SLBSHADOW_STACKVSID(r9)  /* Save VSID */
	std	r0,SLBSHADOW_STACKESID(r9)  /* Save ESID */

	slbie	r6
	slbie	r6		/* Workaround POWER5 < DD2.1 issue */
	slbmte	r7,r0
	isync

2:
END_FTR_SECTION_IFSET(CPU_FTR_SLB)
	clrrdi	r7,r8,THREAD_SHIFT	/* base of new stack */
	/* Note: this uses SWITCH_FRAME_SIZE rather than INT_FRAME_SIZE
	   because we don't need to leave the 288-byte ABI gap at the
	   top of the kernel stack. */
	addi	r7,r7,THREAD_SIZE-SWITCH_FRAME_SIZE

	mr	r1,r8		/* start using new stack pointer */
	std	r7,PACAKSAVE(r13)

	ld	r6,_CCR(r1)
	mtcrf	0xFF,r6

#ifdef CONFIG_ALTIVEC
BEGIN_FTR_SECTION
	ld	r0,THREAD_VRSAVE(r4)
	mtspr	SPRN_VRSAVE,r0		/* if G4, restore VRSAVE reg */
END_FTR_SECTION_IFSET(CPU_FTR_ALTIVEC)
#endif /* CONFIG_ALTIVEC */

	/* r3-r13 are destroyed -- Cort */
	REST_8GPRS(14, r1)
	REST_10GPRS(22, r1)

	/* convert old thread to its task_struct for return value */
	addi	r3,r3,-THREAD
	ld	r7,_NIP(r1)	/* Return to _switch caller in new task */
	mtlr	r7
	addi	r1,r1,SWITCH_FRAME_SIZE
	blr

	.align	7
_GLOBAL(ret_from_except)
	ld	r11,_TRAP(r1)
	andi.	r0,r11,1
	bne	.ret_from_except_lite
	REST_NVGPRS(r1)

_GLOBAL(ret_from_except_lite)
	/*
	 * Disable interrupts so that current_thread_info()->flags
	 * can't change between when we test it and when we return
	 * from the interrupt.
	 */
	mfmsr	r10		/* Get current interrupt state */
	rldicl	r9,r10,48,1	/* clear MSR_EE */
	rotldi	r9,r9,16
	mtmsrd	r9,1		/* Update machine state */

#ifdef CONFIG_PREEMPT
	clrrdi	r9,r1,THREAD_SHIFT	/* current_thread_info() */
	li	r0,_TIF_NEED_RESCHED	/* bits to check */
	ld	r3,_MSR(r1)
	ld	r4,TI_FLAGS(r9)
	/* Move MSR_PR bit in r3 to _TIF_SIGPENDING position in r0 */
	rlwimi	r0,r3,32+TIF_SIGPENDING-MSR_PR_LG,_TIF_SIGPENDING
	and.	r0,r4,r0	/* check NEED_RESCHED and maybe SIGPENDING */
	bne	do_work

#else /* !CONFIG_PREEMPT */
	ld	r3,_MSR(r1)	/* Returning to user mode? */
	andi.	r3,r3,MSR_PR
	beq	restore		/* if not, just restore regs and return */

	/* Check current_thread_info()->flags */
	clrrdi	r9,r1,THREAD_SHIFT
	ld	r4,TI_FLAGS(r9)
	andi.	r0,r4,_TIF_USER_WORK_MASK
	bne	do_work
#endif

restore:
	ld	r5,SOFTE(r1)
#ifdef CONFIG_PPC_ISERIES
BEGIN_FW_FTR_SECTION
	cmpdi	0,r5,0
	beq	4f
	/* Check for pending interrupts (iSeries) */
	ld	r3,PACALPPACAPTR(r13)
	ld	r3,LPPACAANYINT(r3)
	cmpdi	r3,0
	beq+	4f			/* skip do_IRQ if no interrupts */

	li	r3,0
	stb	r3,PACASOFTIRQEN(r13)	/* ensure we are soft-disabled */
	ori	r10,r10,MSR_EE
	mtmsrd	r10			/* hard-enable again */
	addi	r3,r1,STACK_FRAME_OVERHEAD
	bl	.do_IRQ
	b	.ret_from_except_lite		/* loop back and handle more */
4:
END_FW_FTR_SECTION_IFSET(FW_FEATURE_ISERIES)
#endif
	stb	r5,PACASOFTIRQEN(r13)

	/* extract EE bit and use it to restore paca->hard_enabled */
	ld	r3,_MSR(r1)
	rldicl	r4,r3,49,63		/* r0 = (r3 >> 15) & 1 */
	stb	r4,PACAHARDIRQEN(r13)

	ld	r4,_CTR(r1)
	ld	r0,_LINK(r1)
	mtctr	r4
	mtlr	r0
	ld	r4,_XER(r1)
	mtspr	SPRN_XER,r4

	REST_8GPRS(5, r1)

	andi.	r0,r3,MSR_RI
	beq-	unrecov_restore

	stdcx.	r0,0,r1		/* to clear the reservation */

	/*
	 * Clear RI before restoring r13.  If we are returning to
	 * userspace and we take an exception after restoring r13,
	 * we end up corrupting the userspace r13 value.
	 */
	mfmsr	r4
	andc	r4,r4,r0	/* r0 contains MSR_RI here */
	mtmsrd	r4,1

	/*
	 * r13 is our per cpu area, only restore it if we are returning to
	 * userspace
	 */
	andi.	r0,r3,MSR_PR
	beq	1f
	ACCOUNT_CPU_USER_EXIT(r2, r4)
	REST_GPR(13, r1)
1:
	mtspr	SPRN_SRR1,r3

	ld	r2,_CCR(r1)
	mtcrf	0xFF,r2
	ld	r2,_NIP(r1)
	mtspr	SPRN_SRR0,r2

	ld	r0,GPR0(r1)
	ld	r2,GPR2(r1)
	ld	r3,GPR3(r1)
	ld	r4,GPR4(r1)
	ld	r1,GPR1(r1)

	rfid
	b	.	/* prevent speculative execution */

/* Note: this must change if we start using the TIF_NOTIFY_RESUME bit */
do_work:
#ifdef CONFIG_PREEMPT
	andi.	r0,r3,MSR_PR	/* Returning to user mode? */
	bne	user_work
	/* Check that preempt_count() == 0 and interrupts are enabled */
	lwz	r8,TI_PREEMPT(r9)
	cmpwi	cr1,r8,0
	ld	r0,SOFTE(r1)
	cmpdi	r0,0
	crandc	eq,cr1*4+eq,eq
	bne	restore
	/* here we are preempting the current task */
1:
	li	r0,1
	stb	r0,PACASOFTIRQEN(r13)
	stb	r0,PACAHARDIRQEN(r13)
	ori	r10,r10,MSR_EE
	mtmsrd	r10,1		/* reenable interrupts */
	bl	.preempt_schedule
	mfmsr	r10
	clrrdi	r9,r1,THREAD_SHIFT
	rldicl	r10,r10,48,1	/* disable interrupts again */
	rotldi	r10,r10,16
	mtmsrd	r10,1
	ld	r4,TI_FLAGS(r9)
	andi.	r0,r4,_TIF_NEED_RESCHED
	bne	1b
	b	restore

user_work:
#endif
	/* Enable interrupts */
	ori	r10,r10,MSR_EE
	mtmsrd	r10,1

	andi.	r0,r4,_TIF_NEED_RESCHED
	beq	1f
	bl	.schedule
	b	.ret_from_except_lite

1:	bl	.save_nvgprs
	li	r3,0
	addi	r4,r1,STACK_FRAME_OVERHEAD
	bl	.do_signal
	b	.ret_from_except

unrecov_restore:
	addi	r3,r1,STACK_FRAME_OVERHEAD
	bl	.unrecoverable_exception
	b	unrecov_restore

#ifdef CONFIG_PPC_RTAS
/*
 * On CHRP, the Run-Time Abstraction Services (RTAS) have to be
 * called with the MMU off.
 *
 * In addition, we need to be in 32b mode, at least for now.
 * 
 * Note: r3 is an input parameter to rtas, so don't trash it...
 */
_GLOBAL(enter_rtas)
	mflr	r0
	std	r0,16(r1)
        stdu	r1,-RTAS_FRAME_SIZE(r1)	/* Save SP and create stack space. */

	/* Because RTAS is running in 32b mode, it clobbers the high order half
	 * of all registers that it saves.  We therefore save those registers
	 * RTAS might touch to the stack.  (r0, r3-r13 are caller saved)
   	 */
	SAVE_GPR(2, r1)			/* Save the TOC */
	SAVE_GPR(13, r1)		/* Save paca */
	SAVE_8GPRS(14, r1)		/* Save the non-volatiles */
	SAVE_10GPRS(22, r1)		/* ditto */

	mfcr	r4
	std	r4,_CCR(r1)
	mfctr	r5
	std	r5,_CTR(r1)
	mfspr	r6,SPRN_XER
	std	r6,_XER(r1)
	mfdar	r7
	std	r7,_DAR(r1)
	mfdsisr	r8
	std	r8,_DSISR(r1)
	mfsrr0	r9
	std	r9,_SRR0(r1)
	mfsrr1	r10
	std	r10,_SRR1(r1)

	/* Temporary workaround to clear CR until RTAS can be modified to
	 * ignore all bits.
	 */
	li	r0,0
	mtcr	r0

#ifdef CONFIG_BUG	
	/* There is no way it is acceptable to get here with interrupts enabled,
	 * check it with the asm equivalent of WARN_ON
	 */
	lbz	r0,PACASOFTIRQEN(r13)
1:	tdnei	r0,0
	EMIT_BUG_ENTRY 1b,__FILE__,__LINE__,BUGFLAG_WARNING
#endif
	
	/* Hard-disable interrupts */
	mfmsr	r6
	rldicl	r7,r6,48,1
	rotldi	r7,r7,16
	mtmsrd	r7,1

	/* Unfortunately, the stack pointer and the MSR are also clobbered,
	 * so they are saved in the PACA which allows us to restore
	 * our original state after RTAS returns.
         */
	std	r1,PACAR1(r13)
        std	r6,PACASAVEDMSR(r13)

	/* Setup our real return addr */	
	LOAD_REG_ADDR(r4,.rtas_return_loc)
	clrldi	r4,r4,2			/* convert to realmode address */
       	mtlr	r4

	li	r0,0
	ori	r0,r0,MSR_EE|MSR_SE|MSR_BE|MSR_RI
	andc	r0,r6,r0
	
        li      r9,1
        rldicr  r9,r9,MSR_SF_LG,(63-MSR_SF_LG)
	ori	r9,r9,MSR_IR|MSR_DR|MSR_FE0|MSR_FE1|MSR_FP
	andc	r6,r0,r9
	ori	r6,r6,MSR_RI
	sync				/* disable interrupts so SRR0/1 */
	mtmsrd	r0			/* don't get trashed */

	LOAD_REG_ADDR(r4, rtas)
	ld	r5,RTASENTRY(r4)	/* get the rtas->entry value */
	ld	r4,RTASBASE(r4)		/* get the rtas->base value */
	
	mtspr	SPRN_SRR0,r5
	mtspr	SPRN_SRR1,r6
	rfid
	b	.	/* prevent speculative execution */

_STATIC(rtas_return_loc)
	/* relocation is off at this point */
	mfspr	r4,SPRN_SPRG3	        /* Get PACA */
	clrldi	r4,r4,2			/* convert to realmode address */

	mfmsr   r6
	li	r0,MSR_RI
	andc	r6,r6,r0
	sync	
	mtmsrd  r6
        
        ld	r1,PACAR1(r4)           /* Restore our SP */
	LOAD_REG_IMMEDIATE(r3,.rtas_restore_regs)
        ld	r4,PACASAVEDMSR(r4)     /* Restore our MSR */

	mtspr	SPRN_SRR0,r3
	mtspr	SPRN_SRR1,r4
	rfid
	b	.	/* prevent speculative execution */

_STATIC(rtas_restore_regs)
	/* relocation is on at this point */
	REST_GPR(2, r1)			/* Restore the TOC */
	REST_GPR(13, r1)		/* Restore paca */
	REST_8GPRS(14, r1)		/* Restore the non-volatiles */
	REST_10GPRS(22, r1)		/* ditto */

	mfspr	r13,SPRN_SPRG3

	ld	r4,_CCR(r1)
	mtcr	r4
	ld	r5,_CTR(r1)
	mtctr	r5
	ld	r6,_XER(r1)
	mtspr	SPRN_XER,r6
	ld	r7,_DAR(r1)
	mtdar	r7
	ld	r8,_DSISR(r1)
	mtdsisr	r8
	ld	r9,_SRR0(r1)
	mtsrr0	r9
	ld	r10,_SRR1(r1)
	mtsrr1	r10

        addi	r1,r1,RTAS_FRAME_SIZE	/* Unstack our frame */
	ld	r0,16(r1)		/* get return address */

	mtlr    r0
        blr				/* return to caller */

#endif /* CONFIG_PPC_RTAS */

_GLOBAL(enter_prom)
	mflr	r0
	std	r0,16(r1)
        stdu	r1,-PROM_FRAME_SIZE(r1)	/* Save SP and create stack space */

	/* Because PROM is running in 32b mode, it clobbers the high order half
	 * of all registers that it saves.  We therefore save those registers
	 * PROM might touch to the stack.  (r0, r3-r13 are caller saved)
   	 */
	SAVE_8GPRS(2, r1)
	SAVE_GPR(13, r1)
	SAVE_8GPRS(14, r1)
	SAVE_10GPRS(22, r1)
	mfcr	r4
	std	r4,_CCR(r1)
	mfctr	r5
	std	r5,_CTR(r1)
	mfspr	r6,SPRN_XER
	std	r6,_XER(r1)
	mfdar	r7
	std	r7,_DAR(r1)
	mfdsisr	r8
	std	r8,_DSISR(r1)
	mfsrr0	r9
	std	r9,_SRR0(r1)
	mfsrr1	r10
	std	r10,_SRR1(r1)
	mfmsr	r11
	std	r11,_MSR(r1)

	/* Get the PROM entrypoint */
	ld	r0,GPR4(r1)
	mtlr	r0

	/* Switch MSR to 32 bits mode
	 */
        mfmsr   r11
        li      r12,1
        rldicr  r12,r12,MSR_SF_LG,(63-MSR_SF_LG)
        andc    r11,r11,r12
        li      r12,1
        rldicr  r12,r12,MSR_ISF_LG,(63-MSR_ISF_LG)
        andc    r11,r11,r12
        mtmsrd  r11
        isync

	/* Restore arguments & enter PROM here... */
	ld	r3,GPR3(r1)
	blrl

	/* Just make sure that r1 top 32 bits didn't get
	 * corrupt by OF
	 */
	rldicl	r1,r1,0,32

	/* Restore the MSR (back to 64 bits) */
	ld	r0,_MSR(r1)
	mtmsrd	r0
        isync

	/* Restore other registers */
	REST_GPR(2, r1)
	REST_GPR(13, r1)
	REST_8GPRS(14, r1)
	REST_10GPRS(22, r1)
	ld	r4,_CCR(r1)
	mtcr	r4
	ld	r5,_CTR(r1)
	mtctr	r5
	ld	r6,_XER(r1)
	mtspr	SPRN_XER,r6
	ld	r7,_DAR(r1)
	mtdar	r7
	ld	r8,_DSISR(r1)
	mtdsisr	r8
	ld	r9,_SRR0(r1)
	mtsrr0	r9
	ld	r10,_SRR1(r1)
	mtsrr1	r10
	
        addi	r1,r1,PROM_FRAME_SIZE
	ld	r0,16(r1)
	mtlr    r0
        blr