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1/*
2 * linux/arch/arm/kernel/head.S
3 *
4 * Copyright (C) 1994-2002 Russell King
5 * Copyright (c) 2003 ARM Limited
6 * All Rights Reserved
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License version 2 as
10 * published by the Free Software Foundation.
11 *
12 * Kernel startup code for all 32-bit CPUs
13 */
14#include <linux/linkage.h>
15#include <linux/init.h>
16
17#include <asm/assembler.h>
18#include <asm/cp15.h>
19#include <asm/domain.h>
20#include <asm/ptrace.h>
21#include <asm/asm-offsets.h>
22#include <asm/memory.h>
23#include <asm/thread_info.h>
24#include <asm/pgtable.h>
25
26#ifdef CONFIG_DEBUG_LL
27#include <mach/debug-macro.S>
28#endif
29
30/*
31 * swapper_pg_dir is the virtual address of the initial page table.
32 * We place the page tables 16K below KERNEL_RAM_VADDR. Therefore, we must
33 * make sure that KERNEL_RAM_VADDR is correctly set. Currently, we expect
34 * the least significant 16 bits to be 0x8000, but we could probably
35 * relax this restriction to KERNEL_RAM_VADDR >= PAGE_OFFSET + 0x4000.
36 */
37#define KERNEL_RAM_VADDR (PAGE_OFFSET + TEXT_OFFSET)
38#if (KERNEL_RAM_VADDR & 0xffff) != 0x8000
39#error KERNEL_RAM_VADDR must start at 0xXXXX8000
40#endif
41
42#ifdef CONFIG_ARM_LPAE
43 /* LPAE requires an additional page for the PGD */
44#define PG_DIR_SIZE 0x5000
45#define PMD_ORDER 3
46#else
47#define PG_DIR_SIZE 0x4000
48#define PMD_ORDER 2
49#endif
50
51 .globl swapper_pg_dir
52 .equ swapper_pg_dir, KERNEL_RAM_VADDR - PG_DIR_SIZE
53
54 .macro pgtbl, rd, phys
55 add \rd, \phys, #TEXT_OFFSET - PG_DIR_SIZE
56 .endm
57
58#ifdef CONFIG_XIP_KERNEL
59#define KERNEL_START XIP_VIRT_ADDR(CONFIG_XIP_PHYS_ADDR)
60#define KERNEL_END _edata_loc
61#else
62#define KERNEL_START KERNEL_RAM_VADDR
63#define KERNEL_END _end
64#endif
65
66/*
67 * Kernel startup entry point.
68 * ---------------------------
69 *
70 * This is normally called from the decompressor code. The requirements
71 * are: MMU = off, D-cache = off, I-cache = dont care, r0 = 0,
72 * r1 = machine nr, r2 = atags or dtb pointer.
73 *
74 * This code is mostly position independent, so if you link the kernel at
75 * 0xc0008000, you call this at __pa(0xc0008000).
76 *
77 * See linux/arch/arm/tools/mach-types for the complete list of machine
78 * numbers for r1.
79 *
80 * We're trying to keep crap to a minimum; DO NOT add any machine specific
81 * crap here - that's what the boot loader (or in extreme, well justified
82 * circumstances, zImage) is for.
83 */
84 .arm
85
86 __HEAD
87ENTRY(stext)
88
89 THUMB( adr r9, BSYM(1f) ) @ Kernel is always entered in ARM.
90 THUMB( bx r9 ) @ If this is a Thumb-2 kernel,
91 THUMB( .thumb ) @ switch to Thumb now.
92 THUMB(1: )
93
94 setmode PSR_F_BIT | PSR_I_BIT | SVC_MODE, r9 @ ensure svc mode
95 @ and irqs disabled
96 mrc p15, 0, r9, c0, c0 @ get processor id
97 bl __lookup_processor_type @ r5=procinfo r9=cpuid
98 movs r10, r5 @ invalid processor (r5=0)?
99 THUMB( it eq ) @ force fixup-able long branch encoding
100 beq __error_p @ yes, error 'p'
101
102#ifdef CONFIG_ARM_LPAE
103 mrc p15, 0, r3, c0, c1, 4 @ read ID_MMFR0
104 and r3, r3, #0xf @ extract VMSA support
105 cmp r3, #5 @ long-descriptor translation table format?
106 THUMB( it lo ) @ force fixup-able long branch encoding
107 blo __error_p @ only classic page table format
108#endif
109
110#ifndef CONFIG_XIP_KERNEL
111 adr r3, 2f
112 ldmia r3, {r4, r8}
113 sub r4, r3, r4 @ (PHYS_OFFSET - PAGE_OFFSET)
114 add r8, r8, r4 @ PHYS_OFFSET
115#else
116 ldr r8, =PHYS_OFFSET @ always constant in this case
117#endif
118
119 /*
120 * r1 = machine no, r2 = atags or dtb,
121 * r8 = phys_offset, r9 = cpuid, r10 = procinfo
122 */
123 bl __vet_atags
124#ifdef CONFIG_SMP_ON_UP
125 bl __fixup_smp
126#endif
127#ifdef CONFIG_ARM_PATCH_PHYS_VIRT
128 bl __fixup_pv_table
129#endif
130 bl __create_page_tables
131
132 /*
133 * The following calls CPU specific code in a position independent
134 * manner. See arch/arm/mm/proc-*.S for details. r10 = base of
135 * xxx_proc_info structure selected by __lookup_processor_type
136 * above. On return, the CPU will be ready for the MMU to be
137 * turned on, and r0 will hold the CPU control register value.
138 */
139 ldr r13, =__mmap_switched @ address to jump to after
140 @ mmu has been enabled
141 adr lr, BSYM(1f) @ return (PIC) address
142 mov r8, r4 @ set TTBR1 to swapper_pg_dir
143 ARM( add pc, r10, #PROCINFO_INITFUNC )
144 THUMB( add r12, r10, #PROCINFO_INITFUNC )
145 THUMB( mov pc, r12 )
1461: b __enable_mmu
147ENDPROC(stext)
148 .ltorg
149#ifndef CONFIG_XIP_KERNEL
1502: .long .
151 .long PAGE_OFFSET
152#endif
153
154/*
155 * Setup the initial page tables. We only setup the barest
156 * amount which are required to get the kernel running, which
157 * generally means mapping in the kernel code.
158 *
159 * r8 = phys_offset, r9 = cpuid, r10 = procinfo
160 *
161 * Returns:
162 * r0, r3, r5-r7 corrupted
163 * r4 = physical page table address
164 */
165__create_page_tables:
166 pgtbl r4, r8 @ page table address
167
168 /*
169 * Clear the swapper page table
170 */
171 mov r0, r4
172 mov r3, #0
173 add r6, r0, #PG_DIR_SIZE
1741: str r3, [r0], #4
175 str r3, [r0], #4
176 str r3, [r0], #4
177 str r3, [r0], #4
178 teq r0, r6
179 bne 1b
180
181#ifdef CONFIG_ARM_LPAE
182 /*
183 * Build the PGD table (first level) to point to the PMD table. A PGD
184 * entry is 64-bit wide.
185 */
186 mov r0, r4
187 add r3, r4, #0x1000 @ first PMD table address
188 orr r3, r3, #3 @ PGD block type
189 mov r6, #4 @ PTRS_PER_PGD
190 mov r7, #1 << (55 - 32) @ L_PGD_SWAPPER
1911: str r3, [r0], #4 @ set bottom PGD entry bits
192 str r7, [r0], #4 @ set top PGD entry bits
193 add r3, r3, #0x1000 @ next PMD table
194 subs r6, r6, #1
195 bne 1b
196
197 add r4, r4, #0x1000 @ point to the PMD tables
198#endif
199
200 ldr r7, [r10, #PROCINFO_MM_MMUFLAGS] @ mm_mmuflags
201
202 /*
203 * Create identity mapping to cater for __enable_mmu.
204 * This identity mapping will be removed by paging_init().
205 */
206 adr r0, __turn_mmu_on_loc
207 ldmia r0, {r3, r5, r6}
208 sub r0, r0, r3 @ virt->phys offset
209 add r5, r5, r0 @ phys __turn_mmu_on
210 add r6, r6, r0 @ phys __turn_mmu_on_end
211 mov r5, r5, lsr #SECTION_SHIFT
212 mov r6, r6, lsr #SECTION_SHIFT
213
2141: orr r3, r7, r5, lsl #SECTION_SHIFT @ flags + kernel base
215 str r3, [r4, r5, lsl #PMD_ORDER] @ identity mapping
216 cmp r5, r6
217 addlo r5, r5, #1 @ next section
218 blo 1b
219
220 /*
221 * Now setup the pagetables for our kernel direct
222 * mapped region.
223 */
224 mov r3, pc
225 mov r3, r3, lsr #SECTION_SHIFT
226 orr r3, r7, r3, lsl #SECTION_SHIFT
227 add r0, r4, #(KERNEL_START & 0xff000000) >> (SECTION_SHIFT - PMD_ORDER)
228 str r3, [r0, #((KERNEL_START & 0x00f00000) >> SECTION_SHIFT) << PMD_ORDER]!
229 ldr r6, =(KERNEL_END - 1)
230 add r0, r0, #1 << PMD_ORDER
231 add r6, r4, r6, lsr #(SECTION_SHIFT - PMD_ORDER)
2321: cmp r0, r6
233 add r3, r3, #1 << SECTION_SHIFT
234 strls r3, [r0], #1 << PMD_ORDER
235 bls 1b
236
237#ifdef CONFIG_XIP_KERNEL
238 /*
239 * Map some ram to cover our .data and .bss areas.
240 */
241 add r3, r8, #TEXT_OFFSET
242 orr r3, r3, r7
243 add r0, r4, #(KERNEL_RAM_VADDR & 0xff000000) >> (SECTION_SHIFT - PMD_ORDER)
244 str r3, [r0, #(KERNEL_RAM_VADDR & 0x00f00000) >> (SECTION_SHIFT - PMD_ORDER)]!
245 ldr r6, =(_end - 1)
246 add r0, r0, #4
247 add r6, r4, r6, lsr #(SECTION_SHIFT - PMD_ORDER)
2481: cmp r0, r6
249 add r3, r3, #1 << 20
250 strls r3, [r0], #4
251 bls 1b
252#endif
253
254 /*
255 * Then map boot params address in r2 or the first 1MB (2MB with LPAE)
256 * of ram if boot params address is not specified.
257 */
258 mov r0, r2, lsr #SECTION_SHIFT
259 movs r0, r0, lsl #SECTION_SHIFT
260 moveq r0, r8
261 sub r3, r0, r8
262 add r3, r3, #PAGE_OFFSET
263 add r3, r4, r3, lsr #(SECTION_SHIFT - PMD_ORDER)
264 orr r6, r7, r0
265 str r6, [r3]
266
267#ifdef CONFIG_DEBUG_LL
268#if !defined(CONFIG_DEBUG_ICEDCC) && !defined(CONFIG_DEBUG_SEMIHOSTING)
269 /*
270 * Map in IO space for serial debugging.
271 * This allows debug messages to be output
272 * via a serial console before paging_init.
273 */
274 addruart r7, r3, r0
275
276 mov r3, r3, lsr #SECTION_SHIFT
277 mov r3, r3, lsl #PMD_ORDER
278
279 add r0, r4, r3
280 mov r3, r7, lsr #SECTION_SHIFT
281 ldr r7, [r10, #PROCINFO_IO_MMUFLAGS] @ io_mmuflags
282 orr r3, r7, r3, lsl #SECTION_SHIFT
283#ifdef CONFIG_ARM_LPAE
284 mov r7, #1 << (54 - 32) @ XN
285#else
286 orr r3, r3, #PMD_SECT_XN
287#endif
288 str r3, [r0], #4
289#ifdef CONFIG_ARM_LPAE
290 str r7, [r0], #4
291#endif
292
293#else /* CONFIG_DEBUG_ICEDCC || CONFIG_DEBUG_SEMIHOSTING */
294 /* we don't need any serial debugging mappings */
295 ldr r7, [r10, #PROCINFO_IO_MMUFLAGS] @ io_mmuflags
296#endif
297
298#if defined(CONFIG_ARCH_NETWINDER) || defined(CONFIG_ARCH_CATS)
299 /*
300 * If we're using the NetWinder or CATS, we also need to map
301 * in the 16550-type serial port for the debug messages
302 */
303 add r0, r4, #0xff000000 >> (SECTION_SHIFT - PMD_ORDER)
304 orr r3, r7, #0x7c000000
305 str r3, [r0]
306#endif
307#ifdef CONFIG_ARCH_RPC
308 /*
309 * Map in screen at 0x02000000 & SCREEN2_BASE
310 * Similar reasons here - for debug. This is
311 * only for Acorn RiscPC architectures.
312 */
313 add r0, r4, #0x02000000 >> (SECTION_SHIFT - PMD_ORDER)
314 orr r3, r7, #0x02000000
315 str r3, [r0]
316 add r0, r4, #0xd8000000 >> (SECTION_SHIFT - PMD_ORDER)
317 str r3, [r0]
318#endif
319#endif
320#ifdef CONFIG_ARM_LPAE
321 sub r4, r4, #0x1000 @ point to the PGD table
322#endif
323 mov pc, lr
324ENDPROC(__create_page_tables)
325 .ltorg
326 .align
327__turn_mmu_on_loc:
328 .long .
329 .long __turn_mmu_on
330 .long __turn_mmu_on_end
331
332#if defined(CONFIG_SMP)
333 __CPUINIT
334ENTRY(secondary_startup)
335 /*
336 * Common entry point for secondary CPUs.
337 *
338 * Ensure that we're in SVC mode, and IRQs are disabled. Lookup
339 * the processor type - there is no need to check the machine type
340 * as it has already been validated by the primary processor.
341 */
342 setmode PSR_F_BIT | PSR_I_BIT | SVC_MODE, r9
343 mrc p15, 0, r9, c0, c0 @ get processor id
344 bl __lookup_processor_type
345 movs r10, r5 @ invalid processor?
346 moveq r0, #'p' @ yes, error 'p'
347 THUMB( it eq ) @ force fixup-able long branch encoding
348 beq __error_p
349
350 /*
351 * Use the page tables supplied from __cpu_up.
352 */
353 adr r4, __secondary_data
354 ldmia r4, {r5, r7, r12} @ address to jump to after
355 sub lr, r4, r5 @ mmu has been enabled
356 ldr r4, [r7, lr] @ get secondary_data.pgdir
357 add r7, r7, #4
358 ldr r8, [r7, lr] @ get secondary_data.swapper_pg_dir
359 adr lr, BSYM(__enable_mmu) @ return address
360 mov r13, r12 @ __secondary_switched address
361 ARM( add pc, r10, #PROCINFO_INITFUNC ) @ initialise processor
362 @ (return control reg)
363 THUMB( add r12, r10, #PROCINFO_INITFUNC )
364 THUMB( mov pc, r12 )
365ENDPROC(secondary_startup)
366
367 /*
368 * r6 = &secondary_data
369 */
370ENTRY(__secondary_switched)
371 ldr sp, [r7, #4] @ get secondary_data.stack
372 mov fp, #0
373 b secondary_start_kernel
374ENDPROC(__secondary_switched)
375
376 .align
377
378 .type __secondary_data, %object
379__secondary_data:
380 .long .
381 .long secondary_data
382 .long __secondary_switched
383#endif /* defined(CONFIG_SMP) */
384
385
386
387/*
388 * Setup common bits before finally enabling the MMU. Essentially
389 * this is just loading the page table pointer and domain access
390 * registers.
391 *
392 * r0 = cp#15 control register
393 * r1 = machine ID
394 * r2 = atags or dtb pointer
395 * r4 = page table pointer
396 * r9 = processor ID
397 * r13 = *virtual* address to jump to upon completion
398 */
399__enable_mmu:
400#if defined(CONFIG_ALIGNMENT_TRAP) && __LINUX_ARM_ARCH__ < 6
401 orr r0, r0, #CR_A
402#else
403 bic r0, r0, #CR_A
404#endif
405#ifdef CONFIG_CPU_DCACHE_DISABLE
406 bic r0, r0, #CR_C
407#endif
408#ifdef CONFIG_CPU_BPREDICT_DISABLE
409 bic r0, r0, #CR_Z
410#endif
411#ifdef CONFIG_CPU_ICACHE_DISABLE
412 bic r0, r0, #CR_I
413#endif
414#ifdef CONFIG_ARM_LPAE
415 mov r5, #0
416 mcrr p15, 0, r4, r5, c2 @ load TTBR0
417#else
418 mov r5, #(domain_val(DOMAIN_USER, DOMAIN_MANAGER) | \
419 domain_val(DOMAIN_KERNEL, DOMAIN_MANAGER) | \
420 domain_val(DOMAIN_TABLE, DOMAIN_MANAGER) | \
421 domain_val(DOMAIN_IO, DOMAIN_CLIENT))
422 mcr p15, 0, r5, c3, c0, 0 @ load domain access register
423 mcr p15, 0, r4, c2, c0, 0 @ load page table pointer
424#endif
425 b __turn_mmu_on
426ENDPROC(__enable_mmu)
427
428/*
429 * Enable the MMU. This completely changes the structure of the visible
430 * memory space. You will not be able to trace execution through this.
431 * If you have an enquiry about this, *please* check the linux-arm-kernel
432 * mailing list archives BEFORE sending another post to the list.
433 *
434 * r0 = cp#15 control register
435 * r1 = machine ID
436 * r2 = atags or dtb pointer
437 * r9 = processor ID
438 * r13 = *virtual* address to jump to upon completion
439 *
440 * other registers depend on the function called upon completion
441 */
442 .align 5
443 .pushsection .idmap.text, "ax"
444ENTRY(__turn_mmu_on)
445 mov r0, r0
446 instr_sync
447 mcr p15, 0, r0, c1, c0, 0 @ write control reg
448 mrc p15, 0, r3, c0, c0, 0 @ read id reg
449 instr_sync
450 mov r3, r3
451 mov r3, r13
452 mov pc, r3
453__turn_mmu_on_end:
454ENDPROC(__turn_mmu_on)
455 .popsection
456
457
458#ifdef CONFIG_SMP_ON_UP
459 __INIT
460__fixup_smp:
461 and r3, r9, #0x000f0000 @ architecture version
462 teq r3, #0x000f0000 @ CPU ID supported?
463 bne __fixup_smp_on_up @ no, assume UP
464
465 bic r3, r9, #0x00ff0000
466 bic r3, r3, #0x0000000f @ mask 0xff00fff0
467 mov r4, #0x41000000
468 orr r4, r4, #0x0000b000
469 orr r4, r4, #0x00000020 @ val 0x4100b020
470 teq r3, r4 @ ARM 11MPCore?
471 moveq pc, lr @ yes, assume SMP
472
473 mrc p15, 0, r0, c0, c0, 5 @ read MPIDR
474 and r0, r0, #0xc0000000 @ multiprocessing extensions and
475 teq r0, #0x80000000 @ not part of a uniprocessor system?
476 moveq pc, lr @ yes, assume SMP
477
478__fixup_smp_on_up:
479 adr r0, 1f
480 ldmia r0, {r3 - r5}
481 sub r3, r0, r3
482 add r4, r4, r3
483 add r5, r5, r3
484 b __do_fixup_smp_on_up
485ENDPROC(__fixup_smp)
486
487 .align
4881: .word .
489 .word __smpalt_begin
490 .word __smpalt_end
491
492 .pushsection .data
493 .globl smp_on_up
494smp_on_up:
495 ALT_SMP(.long 1)
496 ALT_UP(.long 0)
497 .popsection
498#endif
499
500 .text
501__do_fixup_smp_on_up:
502 cmp r4, r5
503 movhs pc, lr
504 ldmia r4!, {r0, r6}
505 ARM( str r6, [r0, r3] )
506 THUMB( add r0, r0, r3 )
507#ifdef __ARMEB__
508 THUMB( mov r6, r6, ror #16 ) @ Convert word order for big-endian.
509#endif
510 THUMB( strh r6, [r0], #2 ) @ For Thumb-2, store as two halfwords
511 THUMB( mov r6, r6, lsr #16 ) @ to be robust against misaligned r3.
512 THUMB( strh r6, [r0] )
513 b __do_fixup_smp_on_up
514ENDPROC(__do_fixup_smp_on_up)
515
516ENTRY(fixup_smp)
517 stmfd sp!, {r4 - r6, lr}
518 mov r4, r0
519 add r5, r0, r1
520 mov r3, #0
521 bl __do_fixup_smp_on_up
522 ldmfd sp!, {r4 - r6, pc}
523ENDPROC(fixup_smp)
524
525#ifdef CONFIG_ARM_PATCH_PHYS_VIRT
526
527/* __fixup_pv_table - patch the stub instructions with the delta between
528 * PHYS_OFFSET and PAGE_OFFSET, which is assumed to be 16MiB aligned and
529 * can be expressed by an immediate shifter operand. The stub instruction
530 * has a form of '(add|sub) rd, rn, #imm'.
531 */
532 __HEAD
533__fixup_pv_table:
534 adr r0, 1f
535 ldmia r0, {r3-r5, r7}
536 sub r3, r0, r3 @ PHYS_OFFSET - PAGE_OFFSET
537 add r4, r4, r3 @ adjust table start address
538 add r5, r5, r3 @ adjust table end address
539 add r7, r7, r3 @ adjust __pv_phys_offset address
540 str r8, [r7] @ save computed PHYS_OFFSET to __pv_phys_offset
541 mov r6, r3, lsr #24 @ constant for add/sub instructions
542 teq r3, r6, lsl #24 @ must be 16MiB aligned
543THUMB( it ne @ cross section branch )
544 bne __error
545 str r6, [r7, #4] @ save to __pv_offset
546 b __fixup_a_pv_table
547ENDPROC(__fixup_pv_table)
548
549 .align
5501: .long .
551 .long __pv_table_begin
552 .long __pv_table_end
5532: .long __pv_phys_offset
554
555 .text
556__fixup_a_pv_table:
557#ifdef CONFIG_THUMB2_KERNEL
558 lsls r6, #24
559 beq 2f
560 clz r7, r6
561 lsr r6, #24
562 lsl r6, r7
563 bic r6, #0x0080
564 lsrs r7, #1
565 orrcs r6, #0x0080
566 orr r6, r6, r7, lsl #12
567 orr r6, #0x4000
568 b 2f
5691: add r7, r3
570 ldrh ip, [r7, #2]
571 and ip, 0x8f00
572 orr ip, r6 @ mask in offset bits 31-24
573 strh ip, [r7, #2]
5742: cmp r4, r5
575 ldrcc r7, [r4], #4 @ use branch for delay slot
576 bcc 1b
577 bx lr
578#else
579 b 2f
5801: ldr ip, [r7, r3]
581 bic ip, ip, #0x000000ff
582 orr ip, ip, r6 @ mask in offset bits 31-24
583 str ip, [r7, r3]
5842: cmp r4, r5
585 ldrcc r7, [r4], #4 @ use branch for delay slot
586 bcc 1b
587 mov pc, lr
588#endif
589ENDPROC(__fixup_a_pv_table)
590
591ENTRY(fixup_pv_table)
592 stmfd sp!, {r4 - r7, lr}
593 ldr r2, 2f @ get address of __pv_phys_offset
594 mov r3, #0 @ no offset
595 mov r4, r0 @ r0 = table start
596 add r5, r0, r1 @ r1 = table size
597 ldr r6, [r2, #4] @ get __pv_offset
598 bl __fixup_a_pv_table
599 ldmfd sp!, {r4 - r7, pc}
600ENDPROC(fixup_pv_table)
601
602 .align
6032: .long __pv_phys_offset
604
605 .data
606 .globl __pv_phys_offset
607 .type __pv_phys_offset, %object
608__pv_phys_offset:
609 .long 0
610 .size __pv_phys_offset, . - __pv_phys_offset
611__pv_offset:
612 .long 0
613#endif
614
615#include "head-common.S"