summaryrefslogtreecommitdiff
path: root/arch/arm26/boot/compressed/head.S
blob: 2a2cda36d83b9f103c912681d6502c646d662c65 (plain)
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
/*
 *  linux/arch/arm26/boot/compressed/head.S
 *
 *  Copyright (C) 1996-2002 Russell King
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */
#include <linux/linkage.h>

/*
 * Debugging stuff
 *
 * Note that these macros must not contain any code which is not
 * 100% relocatable.  Any attempt to do so will result in a crash.
 * Please select one of the following when turning on debugging.
 */

		.macro	kputc,val
		mov	r0, \val
		bl	putc
		.endm

		.macro	kphex,val,len
		mov	r0, \val
		mov	r1, #\len
		bl	phex
		.endm

		.macro	debug_reloc_start
		.endm

		.macro	debug_reloc_end
		.endm

		.section ".start", #alloc, #execinstr
/*
 * sort out different calling conventions
 */
		.align
start:
		.type	start,#function
		.rept	8
		mov	r0, r0
		.endr

		b	1f
		.word	0x016f2818		@ Magic numbers to help the loader
		.word	start			@ absolute load/run zImage address
		.word	_edata			@ zImage end address
1:		mov	r7, r1			@ save architecture ID
		mov	r8, #0			@ save r0
		teqp	pc, #0x0c000003		@ turn off interrupts

		.text
		adr	r0, LC0
		ldmia	r0, {r1, r2, r3, r4, r5, r6, ip, sp}
		subs	r0, r0, r1		@ calculate the delta offset

		teq	r0, #0			@ if delta is zero, we're
		beq	not_relocated		@ running at the address we
						@ were linked at.

		add	r2, r2, r0		@ different address, so we
		add	r3, r3, r0		@ need to fix up various
		add	r5, r5, r0		@ pointers.
		add	r6, r6, r0
		add	ip, ip, r0
		add	sp, sp, r0

1:		ldr	r1, [r6, #0]		@ relocate entries in the GOT
		add	r1, r1, r0		@ table.  This fixes up the
		str	r1, [r6], #4		@ C references.
		cmp	r6, ip
		blo	1b

not_relocated:	mov	r0, #0
1:		str	r0, [r2], #4		@ clear bss
		str	r0, [r2], #4
		str	r0, [r2], #4
		str	r0, [r2], #4
		cmp	r2, r3
		blo	1b

		bl	cache_on

		mov	r1, sp			@ malloc space above stack
		add	r2, sp, #0x10000	@ 64k max

/*
 * Check to see if we will overwrite ourselves.
 *   r4 = final kernel address
 *   r5 = start of this image
 *   r2 = end of malloc space (and therefore this image)
 * We basically want:
 *   r4 >= r2 -> OK
 *   r4 + image length <= r5 -> OK
 */
		cmp	r4, r2
		bhs	wont_overwrite
		add	r0, r4, #4096*1024	@ 4MB largest kernel size
		cmp	r0, r5
		bls	wont_overwrite

		mov	r5, r2			@ decompress after malloc space
		mov	r0, r5
		mov	r3, r7
		bl	decompress_kernel

		add	r0, r0, #127
		bic	r0, r0, #127		@ align the kernel length
/*
 * r0     = decompressed kernel length
 * r1-r3  = unused
 * r4     = kernel execution address
 * r5     = decompressed kernel start
 * r6     = processor ID
 * r7     = architecture ID
 * r8-r14 = unused
 */
		add	r1, r5, r0		@ end of decompressed kernel
		adr	r2, reloc_start
		ldr	r3, LC1
		add	r3, r2, r3
1:		ldmia	r2!, {r8 - r13}		@ copy relocation code
		stmia	r1!, {r8 - r13}
		ldmia	r2!, {r8 - r13}
		stmia	r1!, {r8 - r13}
		cmp	r2, r3
		blo	1b

		bl	cache_clean_flush
		add	pc, r5, r0		@ call relocation code

/*
 * We're not in danger of overwriting ourselves.  Do this the simple way.
 *
 * r4     = kernel execution address
 * r7     = architecture ID
 */
wont_overwrite:	mov	r0, r4
		mov	r3, r7
		bl	decompress_kernel
		b	call_kernel

		.type	LC0, #object
LC0:		.word	LC0			@ r1
		.word	__bss_start		@ r2
		.word	_end			@ r3
		.word	_load_addr		@ r4
		.word	_start			@ r5
		.word	_got_start		@ r6
		.word	_got_end		@ ip
		.word	user_stack+4096		@ sp
LC1:		.word	reloc_end - reloc_start
		.size	LC0, . - LC0

/*
 * Turn on the cache.  We need to setup some page tables so that we
 * can have both the I and D caches on.
 *
 * We place the page tables 16k down from the kernel execution address,
 * and we hope that nothing else is using it.  If we're using it, we
 * will go pop!
 *
 * On entry,
 *  r4 = kernel execution address
 *  r6 = processor ID
 *  r7 = architecture number
 *  r8 = run-time address of "start"
 * On exit,
 *  r1, r2, r3, r8, r9, r12 corrupted
 * This routine must preserve:
 *  r4, r5, r6, r7
 */
		.align	5
cache_on:	mov	r3, #8			@ cache_on function
		b	call_cache_fn

__setup_mmu:	sub	r3, r4, #16384		@ Page directory size
		bic	r3, r3, #0xff		@ Align the pointer
		bic	r3, r3, #0x3f00
/*
 * Initialise the page tables, turning on the cacheable and bufferable
 * bits for the RAM area only.
 */
		mov	r0, r3
		mov	r8, r0, lsr #18
		mov	r8, r8, lsl #18		@ start of RAM
		add	r9, r8, #0x10000000	@ a reasonable RAM size
		mov	r1, #0x12
		orr	r1, r1, #3 << 10
		add	r2, r3, #16384
1:		cmp	r1, r8			@ if virt > start of RAM
		orrhs	r1, r1, #0x0c		@ set cacheable, bufferable
		cmp	r1, r9			@ if virt > end of RAM
		bichs	r1, r1, #0x0c		@ clear cacheable, bufferable
		str	r1, [r0], #4		@ 1:1 mapping
		add	r1, r1, #1048576
		teq	r0, r2
		bne	1b
/*
 * If ever we are running from Flash, then we surely want the cache
 * to be enabled also for our execution instance...  We map 2MB of it
 * so there is no map overlap problem for up to 1 MB compressed kernel.
 * If the execution is in RAM then we would only be duplicating the above.
 */
		mov	r1, #0x1e
		orr	r1, r1, #3 << 10
		mov	r2, pc, lsr #20
		orr	r1, r1, r2, lsl #20
		add	r0, r3, r2, lsl #2
		str	r1, [r0], #4
		add	r1, r1, #1048576
		str	r1, [r0]
		mov	pc, lr

__armv4_cache_on:
		mov	r12, lr
		bl	__setup_mmu
		mov	r0, #0
		mcr	p15, 0, r0, c7, c10, 4	@ drain write buffer
		mcr	p15, 0, r0, c8, c7, 0	@ flush I,D TLBs
		mrc	p15, 0, r0, c1, c0, 0	@ read control reg
		orr	r0, r0, #0x1000		@ I-cache enable
		orr	r0, r0, #0x0030
		b	__common_cache_on

__arm6_cache_on:
		mov	r12, lr
		bl	__setup_mmu
		mov	r0, #0
		mcr	p15, 0, r0, c7, c0, 0	@ invalidate whole cache v3
		mcr	p15, 0, r0, c5, c0, 0	@ invalidate whole TLB v3
		mov	r0, #0x30
__common_cache_on:
#ifndef DEBUG
		orr	r0, r0, #0x000d		@ Write buffer, mmu
#endif
		mov	r1, #-1
		mcr	p15, 0, r3, c2, c0, 0	@ load page table pointer
		mcr	p15, 0, r1, c3, c0, 0	@ load domain access control
		mcr	p15, 0, r0, c1, c0, 0	@ load control register
		mov	pc, r12

/*
 * All code following this line is relocatable.  It is relocated by
 * the above code to the end of the decompressed kernel image and
 * executed there.  During this time, we have no stacks.
 *
 * r0     = decompressed kernel length
 * r1-r3  = unused
 * r4     = kernel execution address
 * r5     = decompressed kernel start
 * r6     = processor ID
 * r7     = architecture ID
 * r8-r14 = unused
 */
		.align	5
reloc_start:	add	r8, r5, r0
		debug_reloc_start
		mov	r1, r4
1:
		.rept	4
		ldmia	r5!, {r0, r2, r3, r9 - r13}	@ relocate kernel
		stmia	r1!, {r0, r2, r3, r9 - r13}
		.endr

		cmp	r5, r8
		blo	1b
		debug_reloc_end

call_kernel:	bl	cache_clean_flush
		bl	cache_off
		mov	r0, #0
		mov	r1, r7			@ restore architecture number
		mov	pc, r4			@ call kernel

/*
 * Here follow the relocatable cache support functions for the
 * various processors.  This is a generic hook for locating an
 * entry and jumping to an instruction at the specified offset
 * from the start of the block.  Please note this is all position
 * independent code.
 *
 *  r1  = corrupted
 *  r2  = corrupted
 *  r3  = block offset
 *  r6  = corrupted
 *  r12 = corrupted
 */

call_cache_fn:	adr	r12, proc_types
		mrc	p15, 0, r6, c0, c0	@ get processor ID
1:		ldr	r1, [r12, #0]		@ get value
		ldr	r2, [r12, #4]		@ get mask
		eor	r1, r1, r6		@ (real ^ match)
		tst	r1, r2			@       & mask
		addeq	pc, r12, r3		@ call cache function
		add	r12, r12, #4*5
		b	1b

/*
 * Table for cache operations.  This is basically:
 *   - CPU ID match
 *   - CPU ID mask
 *   - 'cache on' method instruction
 *   - 'cache off' method instruction
 *   - 'cache flush' method instruction
 *
 * We match an entry using: ((real_id ^ match) & mask) == 0
 *
 * Writethrough caches generally only need 'on' and 'off'
 * methods.  Writeback caches _must_ have the flush method
 * defined.
 */
		.type	proc_types,#object
proc_types:
		.word	0x41560600		@ ARM6/610
		.word	0xffffffe0
		b	__arm6_cache_off	@ works, but slow
		b	__arm6_cache_off
		mov	pc, lr
@		b	__arm6_cache_on		@ untested
@		b	__arm6_cache_off
@		b	__armv3_cache_flush

		.word	0x41007000		@ ARM7/710
		.word	0xfff8fe00
		b	__arm7_cache_off
		b	__arm7_cache_off
		mov	pc, lr

		.word	0x41807200		@ ARM720T (writethrough)
		.word	0xffffff00
		b	__armv4_cache_on
		b	__armv4_cache_off
		mov	pc, lr

		.word	0x41129200		@ ARM920T
		.word	0xff00fff0
		b	__armv4_cache_on
		b	__armv4_cache_off
		b	__armv4_cache_flush

		.word	0x4401a100		@ sa110 / sa1100
		.word	0xffffffe0
		b	__armv4_cache_on
		b	__armv4_cache_off
		b	__armv4_cache_flush

		.word	0x6901b110		@ sa1110
		.word	0xfffffff0
		b	__armv4_cache_on
		b	__armv4_cache_off
		b	__armv4_cache_flush

		.word	0x69050000		@ xscale
		.word	0xffff0000
		b	__armv4_cache_on
		b	__armv4_cache_off
		b	__armv4_cache_flush

		.word	0			@ unrecognised type
		.word	0
		mov	pc, lr
		mov	pc, lr
		mov	pc, lr

		.size	proc_types, . - proc_types

/*
 * Turn off the Cache and MMU.  ARMv3 does not support
 * reading the control register, but ARMv4 does.
 *
 * On entry,  r6 = processor ID
 * On exit,   r0, r1, r2, r3, r12 corrupted
 * This routine must preserve: r4, r6, r7
 */
		.align	5
cache_off:	mov	r3, #12			@ cache_off function
		b	call_cache_fn

__armv4_cache_off:
		mrc	p15, 0, r0, c1, c0
		bic	r0, r0, #0x000d
		mcr	p15, 0, r0, c1, c0	@ turn MMU and cache off
		mov	r0, #0
		mcr	p15, 0, r0, c7, c7	@ invalidate whole cache v4
		mcr	p15, 0, r0, c8, c7	@ invalidate whole TLB v4
		mov	pc, lr

__arm6_cache_off:
		mov	r0, #0x00000030		@ ARM6 control reg.
		b	__armv3_cache_off

__arm7_cache_off:
		mov	r0, #0x00000070		@ ARM7 control reg.
		b	__armv3_cache_off

__armv3_cache_off:
		mcr	p15, 0, r0, c1, c0, 0	@ turn MMU and cache off
		mov	r0, #0
		mcr	p15, 0, r0, c7, c0, 0	@ invalidate whole cache v3
		mcr	p15, 0, r0, c5, c0, 0	@ invalidate whole TLB v3
		mov	pc, lr

/*
 * Clean and flush the cache to maintain consistency.
 *
 * On entry,
 *  r6 = processor ID
 * On exit,
 *  r1, r2, r3, r12 corrupted
 * This routine must preserve:
 *  r0, r4, r5, r6, r7
 */
		.align	5
cache_clean_flush:
		mov	r3, #16
		b	call_cache_fn

__armv4_cache_flush:
		bic	r1, pc, #31
		add	r2, r1, #65536		@ 2x the largest dcache size
1:		ldr	r12, [r1], #32		@ s/w flush D cache
		teq	r1, r2
		bne	1b

		mcr	p15, 0, r1, c7, c7, 0	@ flush I cache
		mcr	p15, 0, r1, c7, c10, 4	@ drain WB
		mov	pc, lr

__armv3_cache_flush:
		mov	r1, #0
		mcr	p15, 0, r0, c7, c0, 0	@ invalidate whole cache v3
		mov	pc, lr

/*
 * Various debugging routines for printing hex characters and
 * memory, which again must be relocatable.
 */
#ifdef DEBUG
		.type	phexbuf,#object
phexbuf:	.space	12
		.size	phexbuf, . - phexbuf

phex:		adr	r3, phexbuf
		mov	r2, #0
		strb	r2, [r3, r1]
1:		subs	r1, r1, #1
		movmi	r0, r3
		bmi	puts
		and	r2, r0, #15
		mov	r0, r0, lsr #4
		cmp	r2, #10
		addge	r2, r2, #7
		add	r2, r2, #'0'
		strb	r2, [r3, r1]
		b	1b

puts:		loadsp	r3
1:		ldrb	r2, [r0], #1
		teq	r2, #0
		moveq	pc, lr
2:		writeb	r2
		mov	r1, #0x00020000
3:		subs	r1, r1, #1
		bne	3b
		teq	r2, #'\n'
		moveq	r2, #'\r'
		beq	2b
		teq	r0, #0
		bne	1b
		mov	pc, lr
putc:
		mov	r2, r0
		mov	r0, #0
		loadsp	r3
		b	2b

memdump:	mov	r12, r0
		mov	r10, lr
		mov	r11, #0
2:		mov	r0, r11, lsl #2
		add	r0, r0, r12
		mov	r1, #8
		bl	phex
		mov	r0, #':'
		bl	putc
1:		mov	r0, #' '
		bl	putc
		ldr	r0, [r12, r11, lsl #2]
		mov	r1, #8
		bl	phex
		and	r0, r11, #7
		teq	r0, #3
		moveq	r0, #' '
		bleq	putc
		and	r0, r11, #7
		add	r11, r11, #1
		teq	r0, #7
		bne	1b
		mov	r0, #'\n'
		bl	putc
		cmp	r11, #64
		blt	2b
		mov	pc, r10
#endif

reloc_end:

		.align
		.section ".stack", "aw"
user_stack:	.space	4096