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>
26 #if defined(CONFIG_DEBUG_LL) && !defined(CONFIG_DEBUG_SEMIHOSTING)
27 #include CONFIG_DEBUG_LL_INCLUDE
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.
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
42 #ifdef CONFIG_ARM_LPAE
43 /* LPAE requires an additional page for the PGD */
44 #define PG_DIR_SIZE 0x5000
47 #define PG_DIR_SIZE 0x4000
52 .equ swapper_pg_dir, KERNEL_RAM_VADDR - PG_DIR_SIZE
54 .macro pgtbl, rd, phys
55 add \rd, \phys, #TEXT_OFFSET
56 sub \rd, \rd, #PG_DIR_SIZE
60 * Kernel startup entry point.
61 * ---------------------------
63 * This is normally called from the decompressor code. The requirements
64 * are: MMU = off, D-cache = off, I-cache = dont care, r0 = 0,
65 * r1 = machine nr, r2 = atags or dtb pointer.
67 * This code is mostly position independent, so if you link the kernel at
68 * 0xc0008000, you call this at __pa(0xc0008000).
70 * See linux/arch/arm/tools/mach-types for the complete list of machine
73 * We're trying to keep crap to a minimum; DO NOT add any machine specific
74 * crap here - that's what the boot loader (or in extreme, well justified
75 * circumstances, zImage) is for.
81 ARM_BE8(setend be ) @ ensure we are in BE8 mode
83 THUMB( adr r9, BSYM(1f) ) @ Kernel is always entered in ARM.
84 THUMB( bx r9 ) @ If this is a Thumb-2 kernel,
85 THUMB( .thumb ) @ switch to Thumb now.
88 #ifdef CONFIG_ARM_VIRT_EXT
91 @ ensure svc mode and all interrupts masked
92 safe_svcmode_maskall r9
94 mrc p15, 0, r9, c0, c0 @ get processor id
95 bl __lookup_processor_type @ r5=procinfo r9=cpuid
96 movs r10, r5 @ invalid processor (r5=0)?
97 THUMB( it eq ) @ force fixup-able long branch encoding
98 beq __error_p @ yes, error 'p'
100 #ifdef CONFIG_ARM_LPAE
101 mrc p15, 0, r3, c0, c1, 4 @ read ID_MMFR0
102 and r3, r3, #0xf @ extract VMSA support
103 cmp r3, #5 @ long-descriptor translation table format?
104 THUMB( it lo ) @ force fixup-able long branch encoding
105 blo __error_lpae @ only classic page table format
108 #ifndef CONFIG_XIP_KERNEL
111 sub r4, r3, r4 @ (PHYS_OFFSET - PAGE_OFFSET)
112 add r8, r8, r4 @ PHYS_OFFSET
114 ldr r8, =PLAT_PHYS_OFFSET @ always constant in this case
118 * r1 = machine no, r2 = atags or dtb,
119 * r8 = phys_offset, r9 = cpuid, r10 = procinfo
122 #ifdef CONFIG_SMP_ON_UP
125 #ifdef CONFIG_ARM_PATCH_PHYS_VIRT
128 bl __create_page_tables
131 * The following calls CPU specific code in a position independent
132 * manner. See arch/arm/mm/proc-*.S for details. r10 = base of
133 * xxx_proc_info structure selected by __lookup_processor_type
134 * above. On return, the CPU will be ready for the MMU to be
135 * turned on, and r0 will hold the CPU control register value.
137 ldr r13, =__mmap_switched @ address to jump to after
138 @ mmu has been enabled
139 adr lr, BSYM(1f) @ return (PIC) address
140 mov r8, r4 @ set TTBR1 to swapper_pg_dir
141 ARM( add pc, r10, #PROCINFO_INITFUNC )
142 THUMB( add r12, r10, #PROCINFO_INITFUNC )
147 #ifndef CONFIG_XIP_KERNEL
153 * Setup the initial page tables. We only setup the barest
154 * amount which are required to get the kernel running, which
155 * generally means mapping in the kernel code.
157 * r8 = phys_offset, r9 = cpuid, r10 = procinfo
160 * r0, r3, r5-r7 corrupted
161 * r4 = page table (see ARCH_PGD_SHIFT in asm/memory.h)
163 __create_page_tables:
164 pgtbl r4, r8 @ page table address
167 * Clear the swapper page table
171 add r6, r0, #PG_DIR_SIZE
179 #ifdef CONFIG_ARM_LPAE
181 * Build the PGD table (first level) to point to the PMD table. A PGD
182 * entry is 64-bit wide.
185 add r3, r4, #0x1000 @ first PMD table address
186 orr r3, r3, #3 @ PGD block type
187 mov r6, #4 @ PTRS_PER_PGD
188 mov r7, #1 << (55 - 32) @ L_PGD_SWAPPER
190 #ifdef CONFIG_CPU_ENDIAN_BE8
191 str r7, [r0], #4 @ set top PGD entry bits
192 str r3, [r0], #4 @ set bottom PGD entry bits
194 str r3, [r0], #4 @ set bottom PGD entry bits
195 str r7, [r0], #4 @ set top PGD entry bits
197 add r3, r3, #0x1000 @ next PMD table
201 add r4, r4, #0x1000 @ point to the PMD tables
202 #ifdef CONFIG_CPU_ENDIAN_BE8
203 add r4, r4, #4 @ we only write the bottom word
207 ldr r7, [r10, #PROCINFO_MM_MMUFLAGS] @ mm_mmuflags
210 * Create identity mapping to cater for __enable_mmu.
211 * This identity mapping will be removed by paging_init().
213 adr r0, __turn_mmu_on_loc
214 ldmia r0, {r3, r5, r6}
215 sub r0, r0, r3 @ virt->phys offset
216 add r5, r5, r0 @ phys __turn_mmu_on
217 add r6, r6, r0 @ phys __turn_mmu_on_end
218 mov r5, r5, lsr #SECTION_SHIFT
219 mov r6, r6, lsr #SECTION_SHIFT
221 1: orr r3, r7, r5, lsl #SECTION_SHIFT @ flags + kernel base
222 str r3, [r4, r5, lsl #PMD_ORDER] @ identity mapping
224 addlo r5, r5, #1 @ next section
228 * Map our RAM from the start to the end of the kernel .bss section.
230 add r0, r4, #PAGE_OFFSET >> (SECTION_SHIFT - PMD_ORDER)
233 add r6, r4, r6, lsr #(SECTION_SHIFT - PMD_ORDER)
234 1: str r3, [r0], #1 << PMD_ORDER
235 add r3, r3, #1 << SECTION_SHIFT
239 #ifdef CONFIG_XIP_KERNEL
241 * Map the kernel image separately as it is not located in RAM.
243 #define XIP_START XIP_VIRT_ADDR(CONFIG_XIP_PHYS_ADDR)
245 mov r3, r3, lsr #SECTION_SHIFT
246 orr r3, r7, r3, lsl #SECTION_SHIFT
247 add r0, r4, #(XIP_START & 0xff000000) >> (SECTION_SHIFT - PMD_ORDER)
248 str r3, [r0, #((XIP_START & 0x00f00000) >> SECTION_SHIFT) << PMD_ORDER]!
249 ldr r6, =(_edata_loc - 1)
250 add r0, r0, #1 << PMD_ORDER
251 add r6, r4, r6, lsr #(SECTION_SHIFT - PMD_ORDER)
253 add r3, r3, #1 << SECTION_SHIFT
254 strls r3, [r0], #1 << PMD_ORDER
259 * Then map boot params address in r2 if specified.
260 * We map 2 sections in case the ATAGs/DTB crosses a section boundary.
262 mov r0, r2, lsr #SECTION_SHIFT
263 movs r0, r0, lsl #SECTION_SHIFT
265 addne r3, r3, #PAGE_OFFSET
266 addne r3, r4, r3, lsr #(SECTION_SHIFT - PMD_ORDER)
268 strne r6, [r3], #1 << PMD_ORDER
269 addne r6, r6, #1 << SECTION_SHIFT
272 #if defined(CONFIG_ARM_LPAE) && defined(CONFIG_CPU_ENDIAN_BE8)
273 sub r4, r4, #4 @ Fixup page table pointer
274 @ for 64-bit descriptors
277 #ifdef CONFIG_DEBUG_LL
278 #if !defined(CONFIG_DEBUG_ICEDCC) && !defined(CONFIG_DEBUG_SEMIHOSTING)
280 * Map in IO space for serial debugging.
281 * This allows debug messages to be output
282 * via a serial console before paging_init.
286 mov r3, r3, lsr #SECTION_SHIFT
287 mov r3, r3, lsl #PMD_ORDER
290 mov r3, r7, lsr #SECTION_SHIFT
291 ldr r7, [r10, #PROCINFO_IO_MMUFLAGS] @ io_mmuflags
292 orr r3, r7, r3, lsl #SECTION_SHIFT
293 #ifdef CONFIG_ARM_LPAE
294 mov r7, #1 << (54 - 32) @ XN
295 #ifdef CONFIG_CPU_ENDIAN_BE8
303 orr r3, r3, #PMD_SECT_XN
307 #else /* CONFIG_DEBUG_ICEDCC || CONFIG_DEBUG_SEMIHOSTING */
308 /* we don't need any serial debugging mappings */
309 ldr r7, [r10, #PROCINFO_IO_MMUFLAGS] @ io_mmuflags
312 #if defined(CONFIG_ARCH_NETWINDER) || defined(CONFIG_ARCH_CATS)
314 * If we're using the NetWinder or CATS, we also need to map
315 * in the 16550-type serial port for the debug messages
317 add r0, r4, #0xff000000 >> (SECTION_SHIFT - PMD_ORDER)
318 orr r3, r7, #0x7c000000
321 #ifdef CONFIG_ARCH_RPC
323 * Map in screen at 0x02000000 & SCREEN2_BASE
324 * Similar reasons here - for debug. This is
325 * only for Acorn RiscPC architectures.
327 add r0, r4, #0x02000000 >> (SECTION_SHIFT - PMD_ORDER)
328 orr r3, r7, #0x02000000
330 add r0, r4, #0xd8000000 >> (SECTION_SHIFT - PMD_ORDER)
334 #ifdef CONFIG_ARM_LPAE
335 sub r4, r4, #0x1000 @ point to the PGD table
336 mov r4, r4, lsr #ARCH_PGD_SHIFT
339 ENDPROC(__create_page_tables)
345 .long __turn_mmu_on_end
347 #if defined(CONFIG_SMP)
349 ENTRY(secondary_startup)
351 * Common entry point for secondary CPUs.
353 * Ensure that we're in SVC mode, and IRQs are disabled. Lookup
354 * the processor type - there is no need to check the machine type
355 * as it has already been validated by the primary processor.
358 ARM_BE8(setend be) @ ensure we are in BE8 mode
360 #ifdef CONFIG_ARM_VIRT_EXT
361 bl __hyp_stub_install_secondary
363 safe_svcmode_maskall r9
365 mrc p15, 0, r9, c0, c0 @ get processor id
366 bl __lookup_processor_type
367 movs r10, r5 @ invalid processor?
368 moveq r0, #'p' @ yes, error 'p'
369 THUMB( it eq ) @ force fixup-able long branch encoding
373 * Use the page tables supplied from __cpu_up.
375 adr r4, __secondary_data
376 ldmia r4, {r5, r7, r12} @ address to jump to after
377 sub lr, r4, r5 @ mmu has been enabled
378 ldr r4, [r7, lr] @ get secondary_data.pgdir
380 ldr r8, [r7, lr] @ get secondary_data.swapper_pg_dir
381 adr lr, BSYM(__enable_mmu) @ return address
382 mov r13, r12 @ __secondary_switched address
383 ARM( add pc, r10, #PROCINFO_INITFUNC ) @ initialise processor
384 @ (return control reg)
385 THUMB( add r12, r10, #PROCINFO_INITFUNC )
387 ENDPROC(secondary_startup)
390 * r6 = &secondary_data
392 ENTRY(__secondary_switched)
393 ldr sp, [r7, #4] @ get secondary_data.stack
395 b secondary_start_kernel
396 ENDPROC(__secondary_switched)
400 .type __secondary_data, %object
404 .long __secondary_switched
405 #endif /* defined(CONFIG_SMP) */
410 * Setup common bits before finally enabling the MMU. Essentially
411 * this is just loading the page table pointer and domain access
414 * r0 = cp#15 control register
416 * r2 = atags or dtb pointer
417 * r4 = page table (see ARCH_PGD_SHIFT in asm/memory.h)
419 * r13 = *virtual* address to jump to upon completion
422 #if defined(CONFIG_ALIGNMENT_TRAP) && __LINUX_ARM_ARCH__ < 6
427 #ifdef CONFIG_CPU_DCACHE_DISABLE
430 #ifdef CONFIG_CPU_BPREDICT_DISABLE
433 #ifdef CONFIG_CPU_ICACHE_DISABLE
436 #ifndef CONFIG_ARM_LPAE
437 mov r5, #(domain_val(DOMAIN_USER, DOMAIN_MANAGER) | \
438 domain_val(DOMAIN_KERNEL, DOMAIN_MANAGER) | \
439 domain_val(DOMAIN_TABLE, DOMAIN_MANAGER) | \
440 domain_val(DOMAIN_IO, DOMAIN_CLIENT))
441 mcr p15, 0, r5, c3, c0, 0 @ load domain access register
442 mcr p15, 0, r4, c2, c0, 0 @ load page table pointer
445 ENDPROC(__enable_mmu)
448 * Enable the MMU. This completely changes the structure of the visible
449 * memory space. You will not be able to trace execution through this.
450 * If you have an enquiry about this, *please* check the linux-arm-kernel
451 * mailing list archives BEFORE sending another post to the list.
453 * r0 = cp#15 control register
455 * r2 = atags or dtb pointer
457 * r13 = *virtual* address to jump to upon completion
459 * other registers depend on the function called upon completion
462 .pushsection .idmap.text, "ax"
466 mcr p15, 0, r0, c1, c0, 0 @ write control reg
467 mrc p15, 0, r3, c0, c0, 0 @ read id reg
473 ENDPROC(__turn_mmu_on)
477 #ifdef CONFIG_SMP_ON_UP
480 and r3, r9, #0x000f0000 @ architecture version
481 teq r3, #0x000f0000 @ CPU ID supported?
482 bne __fixup_smp_on_up @ no, assume UP
484 bic r3, r9, #0x00ff0000
485 bic r3, r3, #0x0000000f @ mask 0xff00fff0
487 orr r4, r4, #0x0000b000
488 orr r4, r4, #0x00000020 @ val 0x4100b020
489 teq r3, r4 @ ARM 11MPCore?
490 moveq pc, lr @ yes, assume SMP
492 mrc p15, 0, r0, c0, c0, 5 @ read MPIDR
493 and r0, r0, #0xc0000000 @ multiprocessing extensions and
494 teq r0, #0x80000000 @ not part of a uniprocessor system?
495 bne __fixup_smp_on_up @ no, assume UP
497 @ Core indicates it is SMP. Check for Aegis SOC where a single
498 @ Cortex-A9 CPU is present but SMP operations fault.
500 orr r4, r4, #0x0000c000
501 orr r4, r4, #0x00000090
502 teq r3, r4 @ Check for ARM Cortex-A9
503 movne pc, lr @ Not ARM Cortex-A9,
505 @ If a future SoC *does* use 0x0 as the PERIPH_BASE, then the
506 @ below address check will need to be #ifdef'd or equivalent
507 @ for the Aegis platform.
508 mrc p15, 4, r0, c15, c0 @ get SCU base address
509 teq r0, #0x0 @ '0' on actual UP A9 hardware
510 beq __fixup_smp_on_up @ So its an A9 UP
511 ldr r0, [r0, #4] @ read SCU Config
512 ARM_BE8(rev r0, r0) @ byteswap if big endian
513 and r0, r0, #0x3 @ number of CPUs
523 b __do_fixup_smp_on_up
540 __do_fixup_smp_on_up:
544 ARM( str r6, [r0, r3] )
545 THUMB( add r0, r0, r3 )
547 THUMB( mov r6, r6, ror #16 ) @ Convert word order for big-endian.
549 THUMB( strh r6, [r0], #2 ) @ For Thumb-2, store as two halfwords
550 THUMB( mov r6, r6, lsr #16 ) @ to be robust against misaligned r3.
551 THUMB( strh r6, [r0] )
552 b __do_fixup_smp_on_up
553 ENDPROC(__do_fixup_smp_on_up)
556 stmfd sp!, {r4 - r6, lr}
560 bl __do_fixup_smp_on_up
561 ldmfd sp!, {r4 - r6, pc}
565 #define LOW_OFFSET 0x4
566 #define HIGH_OFFSET 0x0
568 #define LOW_OFFSET 0x0
569 #define HIGH_OFFSET 0x4
572 #ifdef CONFIG_ARM_PATCH_PHYS_VIRT
574 /* __fixup_pv_table - patch the stub instructions with the delta between
575 * PHYS_OFFSET and PAGE_OFFSET, which is assumed to be 16MiB aligned and
576 * can be expressed by an immediate shifter operand. The stub instruction
577 * has a form of '(add|sub) rd, rn, #imm'.
584 subs r3, r0, r3 @ PHYS_OFFSET - PAGE_OFFSET
585 add r4, r4, r3 @ adjust table start address
586 add r5, r5, r3 @ adjust table end address
587 add r6, r6, r3 @ adjust __pv_phys_pfn_offset address
588 add r7, r7, r3 @ adjust __pv_offset address
589 mov r0, r8, lsr #12 @ convert to PFN
590 str r0, [r6] @ save computed PHYS_OFFSET to __pv_phys_pfn_offset
591 strcc ip, [r7, #HIGH_OFFSET] @ save to __pv_offset high bits
592 mov r6, r3, lsr #24 @ constant for add/sub instructions
593 teq r3, r6, lsl #24 @ must be 16MiB aligned
594 THUMB( it ne @ cross section branch )
596 str r3, [r7, #LOW_OFFSET] @ save to __pv_offset low bits
598 ENDPROC(__fixup_pv_table)
602 .long __pv_table_begin
604 2: .long __pv_phys_pfn_offset
612 ldr r0, [r6, #HIGH_OFFSET] @ pv_offset high word
613 ldr r6, [r6, #LOW_OFFSET] @ pv_offset low word
616 #ifdef CONFIG_THUMB2_KERNEL
617 moveq r0, #0x200000 @ set bit 21, mov to mvn instruction
626 orr r6, r6, r7, lsl #12
631 ARM_BE8(rev16 ip, ip)
634 orrne ip, r6 @ mask in offset bits 31-24
635 orreq ip, r0 @ mask in offset bits 7-0
636 ARM_BE8(rev16 ip, ip)
640 ARM_BE8(rev16 ip, ip)
642 orr ip, ip, r0, lsr #16
643 ARM_BE8(rev16 ip, ip)
646 ldrcc r7, [r4], #4 @ use branch for delay slot
650 #ifdef CONFIG_CPU_ENDIAN_BE8
651 moveq r0, #0x00004000 @ set bit 22, mov to mvn instruction
653 moveq r0, #0x400000 @ set bit 22, mov to mvn instruction
657 #ifdef CONFIG_CPU_ENDIAN_BE8
658 @ in BE8, we load data in BE, but instructions still in LE
659 bic ip, ip, #0xff000000
660 tst ip, #0x000f0000 @ check the rotation field
661 orrne ip, ip, r6, lsl #24 @ mask in offset bits 31-24
662 biceq ip, ip, #0x00004000 @ clear bit 22
663 orreq ip, ip, r0 @ mask in offset bits 7-0
665 bic ip, ip, #0x000000ff
666 tst ip, #0xf00 @ check the rotation field
667 orrne ip, ip, r6 @ mask in offset bits 31-24
668 biceq ip, ip, #0x400000 @ clear bit 22
669 orreq ip, ip, r0 @ mask in offset bits 7-0
673 ldrcc r7, [r4], #4 @ use branch for delay slot
677 ENDPROC(__fixup_a_pv_table)
682 ENTRY(fixup_pv_table)
683 stmfd sp!, {r4 - r7, lr}
684 mov r3, #0 @ no offset
685 mov r4, r0 @ r0 = table start
686 add r5, r0, r1 @ r1 = table size
687 bl __fixup_a_pv_table
688 ldmfd sp!, {r4 - r7, pc}
689 ENDPROC(fixup_pv_table)
692 .globl __pv_phys_pfn_offset
693 .type __pv_phys_pfn_offset, %object
694 __pv_phys_pfn_offset:
696 .size __pv_phys_pfn_offset, . -__pv_phys_pfn_offset
699 .type __pv_offset, %object
702 .size __pv_offset, . -__pv_offset
705 #include "head-common.S"