2 * linux/arch/arm/kernel/head.S
4 * Copyright (C) 1994-2002 Russell King
5 * Copyright (c) 2003 ARM Limited
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.
12 * Kernel startup code for all 32-bit CPUs
14 #include <linux/linkage.h>
15 #include <linux/init.h>
17 #include <asm/assembler.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 #include <asm/export.h>
27 #if defined(CONFIG_DEBUG_LL) && !defined(CONFIG_DEBUG_SEMIHOSTING)
28 #include CONFIG_DEBUG_LL_INCLUDE
32 * swapper_pg_dir is the virtual address of the initial page table.
33 * We place the page tables 16K below KERNEL_RAM_VADDR. Therefore, we must
34 * make sure that KERNEL_RAM_VADDR is correctly set. Currently, we expect
35 * the least significant 16 bits to be 0x8000, but we could probably
36 * relax this restriction to KERNEL_RAM_VADDR >= PAGE_OFFSET + 0x4000.
38 #define KERNEL_RAM_VADDR (PAGE_OFFSET + TEXT_OFFSET)
39 #if (KERNEL_RAM_VADDR & 0xffff) != 0x8000
40 #error KERNEL_RAM_VADDR must start at 0xXXXX8000
43 #ifdef CONFIG_ARM_LPAE
44 /* LPAE requires an additional page for the PGD */
45 #define PG_DIR_SIZE 0x5000
48 #define PG_DIR_SIZE 0x4000
53 .equ swapper_pg_dir, KERNEL_RAM_VADDR - PG_DIR_SIZE
55 .macro pgtbl, rd, phys
56 add \rd, \phys, #TEXT_OFFSET
57 sub \rd, \rd, #PG_DIR_SIZE
61 * Kernel startup entry point.
62 * ---------------------------
64 * This is normally called from the decompressor code. The requirements
65 * are: MMU = off, D-cache = off, I-cache = dont care, r0 = 0,
66 * r1 = machine nr, r2 = atags or dtb pointer.
68 * This code is mostly position independent, so if you link the kernel at
69 * 0xc0008000, you call this at __pa(0xc0008000).
71 * See linux/arch/arm/tools/mach-types for the complete list of machine
74 * We're trying to keep crap to a minimum; DO NOT add any machine specific
75 * crap here - that's what the boot loader (or in extreme, well justified
76 * circumstances, zImage) is for.
82 ARM_BE8(setend be ) @ ensure we are in BE8 mode
84 THUMB( badr r9, 1f ) @ Kernel is always entered in ARM.
85 THUMB( bx r9 ) @ If this is a Thumb-2 kernel,
86 THUMB( .thumb ) @ switch to Thumb now.
89 #ifdef CONFIG_ARM_VIRT_EXT
92 @ ensure svc mode and all interrupts masked
93 safe_svcmode_maskall r9
95 mrc p15, 0, r9, c0, c0 @ get processor id
96 bl __lookup_processor_type @ r5=procinfo r9=cpuid
97 movs r10, r5 @ invalid processor (r5=0)?
98 THUMB( it eq ) @ force fixup-able long branch encoding
99 beq __error_p @ yes, error 'p'
101 #ifdef CONFIG_ARM_LPAE
102 mrc p15, 0, r3, c0, c1, 4 @ read ID_MMFR0
103 and r3, r3, #0xf @ extract VMSA support
104 cmp r3, #5 @ long-descriptor translation table format?
105 THUMB( it lo ) @ force fixup-able long branch encoding
106 blo __error_lpae @ only classic page table format
109 #ifndef CONFIG_XIP_KERNEL
112 sub r4, r3, r4 @ (PHYS_OFFSET - PAGE_OFFSET)
113 add r8, r8, r4 @ PHYS_OFFSET
115 ldr r8, =PLAT_PHYS_OFFSET @ always constant in this case
119 * r1 = machine no, r2 = atags or dtb,
120 * r8 = phys_offset, r9 = cpuid, r10 = procinfo
123 #ifdef CONFIG_SMP_ON_UP
126 #ifdef CONFIG_ARM_PATCH_PHYS_VIRT
129 bl __create_page_tables
132 * The following calls CPU specific code in a position independent
133 * manner. See arch/arm/mm/proc-*.S for details. r10 = base of
134 * xxx_proc_info structure selected by __lookup_processor_type
137 * The processor init function will be called with:
139 * r2 - boot data (atags/dt) pointer
140 * r4 - translation table base (low word)
141 * r5 - translation table base (high word, if LPAE)
142 * r8 - translation table base 1 (pfn if LPAE)
144 * r13 - virtual address for __enable_mmu -> __turn_mmu_on
146 * On return, the CPU will be ready for the MMU to be turned on,
147 * r0 will hold the CPU control register value, r1, r2, r4, and
148 * r9 will be preserved. r5 will also be preserved if LPAE.
150 ldr r13, =__mmap_switched @ address to jump to after
151 @ mmu has been enabled
152 badr lr, 1f @ return (PIC) address
153 #ifdef CONFIG_ARM_LPAE
154 mov r5, #0 @ high TTBR0
155 mov r8, r4, lsr #12 @ TTBR1 is swapper_pg_dir pfn
157 mov r8, r4 @ set TTBR1 to swapper_pg_dir
159 ldr r12, [r10, #PROCINFO_INITFUNC]
165 #ifndef CONFIG_XIP_KERNEL
171 * Setup the initial page tables. We only setup the barest
172 * amount which are required to get the kernel running, which
173 * generally means mapping in the kernel code.
175 * r8 = phys_offset, r9 = cpuid, r10 = procinfo
178 * r0, r3, r5-r7 corrupted
179 * r4 = physical page table address
181 __create_page_tables:
182 pgtbl r4, r8 @ page table address
185 * Clear the swapper page table
189 add r6, r0, #PG_DIR_SIZE
197 #ifdef CONFIG_ARM_LPAE
199 * Build the PGD table (first level) to point to the PMD table. A PGD
200 * entry is 64-bit wide.
203 add r3, r4, #0x1000 @ first PMD table address
204 orr r3, r3, #3 @ PGD block type
205 mov r6, #4 @ PTRS_PER_PGD
206 mov r7, #1 << (55 - 32) @ L_PGD_SWAPPER
208 #ifdef CONFIG_CPU_ENDIAN_BE8
209 str r7, [r0], #4 @ set top PGD entry bits
210 str r3, [r0], #4 @ set bottom PGD entry bits
212 str r3, [r0], #4 @ set bottom PGD entry bits
213 str r7, [r0], #4 @ set top PGD entry bits
215 add r3, r3, #0x1000 @ next PMD table
219 add r4, r4, #0x1000 @ point to the PMD tables
220 #ifdef CONFIG_CPU_ENDIAN_BE8
221 add r4, r4, #4 @ we only write the bottom word
225 ldr r7, [r10, #PROCINFO_MM_MMUFLAGS] @ mm_mmuflags
228 * Create identity mapping to cater for __enable_mmu.
229 * This identity mapping will be removed by paging_init().
231 adr r0, __turn_mmu_on_loc
232 ldmia r0, {r3, r5, r6}
233 sub r0, r0, r3 @ virt->phys offset
234 add r5, r5, r0 @ phys __turn_mmu_on
235 add r6, r6, r0 @ phys __turn_mmu_on_end
236 mov r5, r5, lsr #SECTION_SHIFT
237 mov r6, r6, lsr #SECTION_SHIFT
239 1: orr r3, r7, r5, lsl #SECTION_SHIFT @ flags + kernel base
240 str r3, [r4, r5, lsl #PMD_ORDER] @ identity mapping
242 addlo r5, r5, #1 @ next section
246 * Map our RAM from the start to the end of the kernel .bss section.
248 add r0, r4, #PAGE_OFFSET >> (SECTION_SHIFT - PMD_ORDER)
251 add r6, r4, r6, lsr #(SECTION_SHIFT - PMD_ORDER)
252 1: str r3, [r0], #1 << PMD_ORDER
253 add r3, r3, #1 << SECTION_SHIFT
257 #ifdef CONFIG_XIP_KERNEL
259 * Map the kernel image separately as it is not located in RAM.
261 #define XIP_START XIP_VIRT_ADDR(CONFIG_XIP_PHYS_ADDR)
263 mov r3, r3, lsr #SECTION_SHIFT
264 orr r3, r7, r3, lsl #SECTION_SHIFT
265 add r0, r4, #(XIP_START & 0xff000000) >> (SECTION_SHIFT - PMD_ORDER)
266 str r3, [r0, #((XIP_START & 0x00f00000) >> SECTION_SHIFT) << PMD_ORDER]!
267 ldr r6, =(_edata_loc - 1)
268 add r0, r0, #1 << PMD_ORDER
269 add r6, r4, r6, lsr #(SECTION_SHIFT - PMD_ORDER)
271 add r3, r3, #1 << SECTION_SHIFT
272 strls r3, [r0], #1 << PMD_ORDER
277 * Then map boot params address in r2 if specified.
278 * We map 2 sections in case the ATAGs/DTB crosses a section boundary.
280 mov r0, r2, lsr #SECTION_SHIFT
281 movs r0, r0, lsl #SECTION_SHIFT
283 addne r3, r3, #PAGE_OFFSET
284 addne r3, r4, r3, lsr #(SECTION_SHIFT - PMD_ORDER)
286 strne r6, [r3], #1 << PMD_ORDER
287 addne r6, r6, #1 << SECTION_SHIFT
290 #if defined(CONFIG_ARM_LPAE) && defined(CONFIG_CPU_ENDIAN_BE8)
291 sub r4, r4, #4 @ Fixup page table pointer
292 @ for 64-bit descriptors
295 #ifdef CONFIG_DEBUG_LL
296 #if !defined(CONFIG_DEBUG_ICEDCC) && !defined(CONFIG_DEBUG_SEMIHOSTING)
298 * Map in IO space for serial debugging.
299 * This allows debug messages to be output
300 * via a serial console before paging_init.
304 mov r3, r3, lsr #SECTION_SHIFT
305 mov r3, r3, lsl #PMD_ORDER
308 mov r3, r7, lsr #SECTION_SHIFT
309 ldr r7, [r10, #PROCINFO_IO_MMUFLAGS] @ io_mmuflags
310 orr r3, r7, r3, lsl #SECTION_SHIFT
311 #ifdef CONFIG_ARM_LPAE
312 mov r7, #1 << (54 - 32) @ XN
313 #ifdef CONFIG_CPU_ENDIAN_BE8
321 orr r3, r3, #PMD_SECT_XN
325 #else /* CONFIG_DEBUG_ICEDCC || CONFIG_DEBUG_SEMIHOSTING */
326 /* we don't need any serial debugging mappings */
327 ldr r7, [r10, #PROCINFO_IO_MMUFLAGS] @ io_mmuflags
330 #if defined(CONFIG_ARCH_NETWINDER) || defined(CONFIG_ARCH_CATS)
332 * If we're using the NetWinder or CATS, we also need to map
333 * in the 16550-type serial port for the debug messages
335 add r0, r4, #0xff000000 >> (SECTION_SHIFT - PMD_ORDER)
336 orr r3, r7, #0x7c000000
339 #ifdef CONFIG_ARCH_RPC
341 * Map in screen at 0x02000000 & SCREEN2_BASE
342 * Similar reasons here - for debug. This is
343 * only for Acorn RiscPC architectures.
345 add r0, r4, #0x02000000 >> (SECTION_SHIFT - PMD_ORDER)
346 orr r3, r7, #0x02000000
348 add r0, r4, #0xd8000000 >> (SECTION_SHIFT - PMD_ORDER)
352 #ifdef CONFIG_ARM_LPAE
353 sub r4, r4, #0x1000 @ point to the PGD table
356 ENDPROC(__create_page_tables)
362 .long __turn_mmu_on_end
364 #if defined(CONFIG_SMP)
367 ENTRY(secondary_startup_arm)
368 THUMB( badr r9, 1f ) @ Kernel is entered in ARM.
369 THUMB( bx r9 ) @ If this is a Thumb-2 kernel,
370 THUMB( .thumb ) @ switch to Thumb now.
372 ENTRY(secondary_startup)
374 * Common entry point for secondary CPUs.
376 * Ensure that we're in SVC mode, and IRQs are disabled. Lookup
377 * the processor type - there is no need to check the machine type
378 * as it has already been validated by the primary processor.
381 ARM_BE8(setend be) @ ensure we are in BE8 mode
383 #ifdef CONFIG_ARM_VIRT_EXT
384 bl __hyp_stub_install_secondary
386 safe_svcmode_maskall r9
388 mrc p15, 0, r9, c0, c0 @ get processor id
389 bl __lookup_processor_type
390 movs r10, r5 @ invalid processor?
391 moveq r0, #'p' @ yes, error 'p'
392 THUMB( it eq ) @ force fixup-able long branch encoding
396 * Use the page tables supplied from __cpu_up.
398 adr r4, __secondary_data
399 ldmia r4, {r5, r7, r12} @ address to jump to after
400 sub lr, r4, r5 @ mmu has been enabled
402 ldrd r4, [r3, #0] @ get secondary_data.pgdir
403 ARM_BE8(eor r4, r4, r5) @ Swap r5 and r4 in BE:
404 ARM_BE8(eor r5, r4, r5) @ it can be done in 3 steps
405 ARM_BE8(eor r4, r4, r5) @ without using a temp reg.
406 ldr r8, [r3, #8] @ get secondary_data.swapper_pg_dir
407 badr lr, __enable_mmu @ return address
408 mov r13, r12 @ __secondary_switched address
409 ldr r12, [r10, #PROCINFO_INITFUNC]
410 add r12, r12, r10 @ initialise processor
411 @ (return control reg)
413 ENDPROC(secondary_startup)
414 ENDPROC(secondary_startup_arm)
417 * r6 = &secondary_data
419 ENTRY(__secondary_switched)
420 ldr sp, [r7, #12] @ get secondary_data.stack
422 b secondary_start_kernel
423 ENDPROC(__secondary_switched)
427 .type __secondary_data, %object
431 .long __secondary_switched
432 #endif /* defined(CONFIG_SMP) */
437 * Setup common bits before finally enabling the MMU. Essentially
438 * this is just loading the page table pointer and domain access
439 * registers. All these registers need to be preserved by the
440 * processor setup function (or set in the case of r0)
442 * r0 = cp#15 control register
444 * r2 = atags or dtb pointer
445 * r4 = TTBR pointer (low word)
446 * r5 = TTBR pointer (high word if LPAE)
448 * r13 = *virtual* address to jump to upon completion
451 #if defined(CONFIG_ALIGNMENT_TRAP) && __LINUX_ARM_ARCH__ < 6
456 #ifdef CONFIG_CPU_DCACHE_DISABLE
459 #ifdef CONFIG_CPU_BPREDICT_DISABLE
462 #ifdef CONFIG_CPU_ICACHE_DISABLE
465 #ifdef CONFIG_ARM_LPAE
466 mcrr p15, 0, r4, r5, c2 @ load TTBR0
469 mcr p15, 0, r5, c3, c0, 0 @ load domain access register
470 mcr p15, 0, r4, c2, c0, 0 @ load page table pointer
473 ENDPROC(__enable_mmu)
476 * Enable the MMU. This completely changes the structure of the visible
477 * memory space. You will not be able to trace execution through this.
478 * If you have an enquiry about this, *please* check the linux-arm-kernel
479 * mailing list archives BEFORE sending another post to the list.
481 * r0 = cp#15 control register
483 * r2 = atags or dtb pointer
485 * r13 = *virtual* address to jump to upon completion
487 * other registers depend on the function called upon completion
490 .pushsection .idmap.text, "ax"
494 mcr p15, 0, r0, c1, c0, 0 @ write control reg
495 mrc p15, 0, r3, c0, c0, 0 @ read id reg
501 ENDPROC(__turn_mmu_on)
505 #ifdef CONFIG_SMP_ON_UP
508 and r3, r9, #0x000f0000 @ architecture version
509 teq r3, #0x000f0000 @ CPU ID supported?
510 bne __fixup_smp_on_up @ no, assume UP
512 bic r3, r9, #0x00ff0000
513 bic r3, r3, #0x0000000f @ mask 0xff00fff0
515 orr r4, r4, #0x0000b000
516 orr r4, r4, #0x00000020 @ val 0x4100b020
517 teq r3, r4 @ ARM 11MPCore?
518 reteq lr @ yes, assume SMP
520 mrc p15, 0, r0, c0, c0, 5 @ read MPIDR
521 and r0, r0, #0xc0000000 @ multiprocessing extensions and
522 teq r0, #0x80000000 @ not part of a uniprocessor system?
523 bne __fixup_smp_on_up @ no, assume UP
525 @ Core indicates it is SMP. Check for Aegis SOC where a single
526 @ Cortex-A9 CPU is present but SMP operations fault.
528 orr r4, r4, #0x0000c000
529 orr r4, r4, #0x00000090
530 teq r3, r4 @ Check for ARM Cortex-A9
531 retne lr @ Not ARM Cortex-A9,
533 @ If a future SoC *does* use 0x0 as the PERIPH_BASE, then the
534 @ below address check will need to be #ifdef'd or equivalent
535 @ for the Aegis platform.
536 mrc p15, 4, r0, c15, c0 @ get SCU base address
537 teq r0, #0x0 @ '0' on actual UP A9 hardware
538 beq __fixup_smp_on_up @ So its an A9 UP
539 ldr r0, [r0, #4] @ read SCU Config
540 ARM_BE8(rev r0, r0) @ byteswap if big endian
541 and r0, r0, #0x3 @ number of CPUs
551 b __do_fixup_smp_on_up
568 __do_fixup_smp_on_up:
572 ARM( str r6, [r0, r3] )
573 THUMB( add r0, r0, r3 )
575 THUMB( mov r6, r6, ror #16 ) @ Convert word order for big-endian.
577 THUMB( strh r6, [r0], #2 ) @ For Thumb-2, store as two halfwords
578 THUMB( mov r6, r6, lsr #16 ) @ to be robust against misaligned r3.
579 THUMB( strh r6, [r0] )
580 b __do_fixup_smp_on_up
581 ENDPROC(__do_fixup_smp_on_up)
584 stmfd sp!, {r4 - r6, lr}
588 bl __do_fixup_smp_on_up
589 ldmfd sp!, {r4 - r6, pc}
593 #define LOW_OFFSET 0x4
594 #define HIGH_OFFSET 0x0
596 #define LOW_OFFSET 0x0
597 #define HIGH_OFFSET 0x4
600 #ifdef CONFIG_ARM_PATCH_PHYS_VIRT
602 /* __fixup_pv_table - patch the stub instructions with the delta between
603 * PHYS_OFFSET and PAGE_OFFSET, which is assumed to be 16MiB aligned and
604 * can be expressed by an immediate shifter operand. The stub instruction
605 * has a form of '(add|sub) rd, rn, #imm'.
612 subs r3, r0, r3 @ PHYS_OFFSET - PAGE_OFFSET
613 add r4, r4, r3 @ adjust table start address
614 add r5, r5, r3 @ adjust table end address
615 add r6, r6, r3 @ adjust __pv_phys_pfn_offset address
616 add r7, r7, r3 @ adjust __pv_offset address
617 mov r0, r8, lsr #PAGE_SHIFT @ convert to PFN
618 str r0, [r6] @ save computed PHYS_OFFSET to __pv_phys_pfn_offset
619 strcc ip, [r7, #HIGH_OFFSET] @ save to __pv_offset high bits
620 mov r6, r3, lsr #24 @ constant for add/sub instructions
621 teq r3, r6, lsl #24 @ must be 16MiB aligned
622 THUMB( it ne @ cross section branch )
624 str r3, [r7, #LOW_OFFSET] @ save to __pv_offset low bits
626 ENDPROC(__fixup_pv_table)
630 .long __pv_table_begin
632 2: .long __pv_phys_pfn_offset
640 ldr r0, [r6, #HIGH_OFFSET] @ pv_offset high word
641 ldr r6, [r6, #LOW_OFFSET] @ pv_offset low word
644 #ifdef CONFIG_THUMB2_KERNEL
645 moveq r0, #0x200000 @ set bit 21, mov to mvn instruction
654 orr r6, r6, r7, lsl #12
659 ARM_BE8(rev16 ip, ip)
662 orrne ip, r6 @ mask in offset bits 31-24
663 orreq ip, r0 @ mask in offset bits 7-0
664 ARM_BE8(rev16 ip, ip)
668 ARM_BE8(rev16 ip, ip)
670 orr ip, ip, r0, lsr #16
671 ARM_BE8(rev16 ip, ip)
674 ldrcc r7, [r4], #4 @ use branch for delay slot
678 #ifdef CONFIG_CPU_ENDIAN_BE8
679 moveq r0, #0x00004000 @ set bit 22, mov to mvn instruction
681 moveq r0, #0x400000 @ set bit 22, mov to mvn instruction
685 #ifdef CONFIG_CPU_ENDIAN_BE8
686 @ in BE8, we load data in BE, but instructions still in LE
687 bic ip, ip, #0xff000000
688 tst ip, #0x000f0000 @ check the rotation field
689 orrne ip, ip, r6, lsl #24 @ mask in offset bits 31-24
690 biceq ip, ip, #0x00004000 @ clear bit 22
691 orreq ip, ip, r0 @ mask in offset bits 7-0
693 bic ip, ip, #0x000000ff
694 tst ip, #0xf00 @ check the rotation field
695 orrne ip, ip, r6 @ mask in offset bits 31-24
696 biceq ip, ip, #0x400000 @ clear bit 22
697 orreq ip, ip, r0 @ mask in offset bits 7-0
701 ldrcc r7, [r4], #4 @ use branch for delay slot
705 ENDPROC(__fixup_a_pv_table)
710 ENTRY(fixup_pv_table)
711 stmfd sp!, {r4 - r7, lr}
712 mov r3, #0 @ no offset
713 mov r4, r0 @ r0 = table start
714 add r5, r0, r1 @ r1 = table size
715 bl __fixup_a_pv_table
716 ldmfd sp!, {r4 - r7, pc}
717 ENDPROC(fixup_pv_table)
720 .globl __pv_phys_pfn_offset
721 .type __pv_phys_pfn_offset, %object
722 __pv_phys_pfn_offset:
724 .size __pv_phys_pfn_offset, . -__pv_phys_pfn_offset
727 .type __pv_offset, %object
730 .size __pv_offset, . -__pv_offset
731 EXPORT_SYMBOL(__pv_phys_pfn_offset)
732 EXPORT_SYMBOL(__pv_offset)
735 #include "head-common.S"