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 #ifdef CONFIG_DEBUG_LL
27 #include <mach/debug-macro.S>
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 - PG_DIR_SIZE
58 #ifdef CONFIG_XIP_KERNEL
59 #define KERNEL_START XIP_VIRT_ADDR(CONFIG_XIP_PHYS_ADDR)
60 #define KERNEL_END _edata_loc
62 #define KERNEL_START KERNEL_RAM_VADDR
63 #define KERNEL_END _end
67 * Kernel startup entry point.
68 * ---------------------------
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.
74 * This code is mostly position independent, so if you link the kernel at
75 * 0xc0008000, you call this at __pa(0xc0008000).
77 * See linux/arch/arm/tools/mach-types for the complete list of machine
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.
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.
94 setmode PSR_F_BIT | PSR_I_BIT | SVC_MODE, r9 @ ensure svc mode
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'
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
110 #ifndef CONFIG_XIP_KERNEL
113 sub r4, r3, r4 @ (PHYS_OFFSET - PAGE_OFFSET)
114 add r8, r8, r4 @ PHYS_OFFSET
116 ldr r8, =PHYS_OFFSET @ always constant in this case
120 * r1 = machine no, r2 = atags or dtb,
121 * r8 = phys_offset, r9 = cpuid, r10 = procinfo
124 #ifdef CONFIG_SMP_ON_UP
127 #ifdef CONFIG_ARM_PATCH_PHYS_VIRT
130 bl __create_page_tables
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.
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 )
149 #ifndef CONFIG_XIP_KERNEL
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.
159 * r8 = phys_offset, r9 = cpuid, r10 = procinfo
162 * r0, r3, r5-r7 corrupted
163 * r4 = physical page table address
165 __create_page_tables:
166 pgtbl r4, r8 @ page table address
169 * Clear the swapper page table
173 add r6, r0, #PG_DIR_SIZE
181 #ifdef CONFIG_ARM_LPAE
183 * Build the PGD table (first level) to point to the PMD table. A PGD
184 * entry is 64-bit wide.
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
191 1: 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
197 add r4, r4, #0x1000 @ point to the PMD tables
200 ldr r7, [r10, #PROCINFO_MM_MMUFLAGS] @ mm_mmuflags
203 * Create identity mapping to cater for __enable_mmu.
204 * This identity mapping will be removed by paging_init().
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
214 1: orr r3, r7, r5, lsl #SECTION_SHIFT @ flags + kernel base
215 str r3, [r4, r5, lsl #PMD_ORDER] @ identity mapping
217 addlo r5, r5, #1 @ next section
221 * Now setup the pagetables for our kernel direct
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)
233 add r3, r3, #1 << SECTION_SHIFT
234 strls r3, [r0], #1 << PMD_ORDER
237 #ifdef CONFIG_XIP_KERNEL
239 * Map some ram to cover our .data and .bss areas.
241 add r3, r8, #TEXT_OFFSET
243 add r0, r4, #(KERNEL_RAM_VADDR & 0xff000000) >> (SECTION_SHIFT - PMD_ORDER)
244 str r3, [r0, #(KERNEL_RAM_VADDR & 0x00f00000) >> (SECTION_SHIFT - PMD_ORDER)]!
247 add r6, r4, r6, lsr #(SECTION_SHIFT - PMD_ORDER)
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.
258 mov r0, r2, lsr #SECTION_SHIFT
259 movs r0, r0, lsl #SECTION_SHIFT
262 add r3, r3, #PAGE_OFFSET
263 add r3, r4, r3, lsr #(SECTION_SHIFT - PMD_ORDER)
267 #ifdef CONFIG_DEBUG_LL
268 #if !defined(CONFIG_DEBUG_ICEDCC) && !defined(CONFIG_DEBUG_SEMIHOSTING)
270 * Map in IO space for serial debugging.
271 * This allows debug messages to be output
272 * via a serial console before paging_init.
276 mov r3, r3, lsr #SECTION_SHIFT
277 mov r3, r3, lsl #PMD_ORDER
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
286 orr r3, r3, #PMD_SECT_XN
289 #ifdef CONFIG_ARM_LPAE
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
298 #if defined(CONFIG_ARCH_NETWINDER) || defined(CONFIG_ARCH_CATS)
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
303 add r0, r4, #0xff000000 >> (SECTION_SHIFT - PMD_ORDER)
304 orr r3, r7, #0x7c000000
307 #ifdef CONFIG_ARCH_RPC
309 * Map in screen at 0x02000000 & SCREEN2_BASE
310 * Similar reasons here - for debug. This is
311 * only for Acorn RiscPC architectures.
313 add r0, r4, #0x02000000 >> (SECTION_SHIFT - PMD_ORDER)
314 orr r3, r7, #0x02000000
316 add r0, r4, #0xd8000000 >> (SECTION_SHIFT - PMD_ORDER)
320 #ifdef CONFIG_ARM_LPAE
321 sub r4, r4, #0x1000 @ point to the PGD table
324 ENDPROC(__create_page_tables)
330 .long __turn_mmu_on_end
332 #if defined(CONFIG_SMP)
334 ENTRY(secondary_startup)
336 * Common entry point for secondary CPUs.
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.
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
351 * Use the page tables supplied from __cpu_up.
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
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 )
365 ENDPROC(secondary_startup)
368 * r6 = &secondary_data
370 ENTRY(__secondary_switched)
371 ldr sp, [r7, #4] @ get secondary_data.stack
373 b secondary_start_kernel
374 ENDPROC(__secondary_switched)
378 .type __secondary_data, %object
382 .long __secondary_switched
383 #endif /* defined(CONFIG_SMP) */
388 * Setup common bits before finally enabling the MMU. Essentially
389 * this is just loading the page table pointer and domain access
392 * r0 = cp#15 control register
394 * r2 = atags or dtb pointer
395 * r4 = page table pointer
397 * r13 = *virtual* address to jump to upon completion
400 #if defined(CONFIG_ALIGNMENT_TRAP) && __LINUX_ARM_ARCH__ < 6
405 #ifdef CONFIG_CPU_DCACHE_DISABLE
408 #ifdef CONFIG_CPU_BPREDICT_DISABLE
411 #ifdef CONFIG_CPU_ICACHE_DISABLE
414 #ifdef CONFIG_ARM_LPAE
416 mcrr p15, 0, r4, r5, c2 @ load TTBR0
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
426 ENDPROC(__enable_mmu)
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.
434 * r0 = cp#15 control register
436 * r2 = atags or dtb pointer
438 * r13 = *virtual* address to jump to upon completion
440 * other registers depend on the function called upon completion
443 .pushsection .idmap.text, "ax"
447 mcr p15, 0, r0, c1, c0, 0 @ write control reg
448 mrc p15, 0, r3, c0, c0, 0 @ read id reg
454 ENDPROC(__turn_mmu_on)
458 #ifdef CONFIG_SMP_ON_UP
461 and r3, r9, #0x000f0000 @ architecture version
462 teq r3, #0x000f0000 @ CPU ID supported?
463 bne __fixup_smp_on_up @ no, assume UP
465 bic r3, r9, #0x00ff0000
466 bic r3, r3, #0x0000000f @ mask 0xff00fff0
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
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
484 b __do_fixup_smp_on_up
501 __do_fixup_smp_on_up:
505 ARM( str r6, [r0, r3] )
506 THUMB( add r0, r0, r3 )
508 THUMB( mov r6, r6, ror #16 ) @ Convert word order for big-endian.
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
514 ENDPROC(__do_fixup_smp_on_up)
517 stmfd sp!, {r4 - r6, lr}
521 bl __do_fixup_smp_on_up
522 ldmfd sp!, {r4 - r6, pc}
525 #ifdef CONFIG_ARM_PATCH_PHYS_VIRT
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'.
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
543 THUMB( it ne @ cross section branch )
545 str r6, [r7, #4] @ save to __pv_offset
547 ENDPROC(__fixup_pv_table)
551 .long __pv_table_begin
553 2: .long __pv_phys_offset
557 #ifdef CONFIG_THUMB2_KERNEL
566 orr r6, r6, r7, lsl #12
572 orr ip, r6 @ mask in offset bits 31-24
575 ldrcc r7, [r4], #4 @ use branch for delay slot
581 bic ip, ip, #0x000000ff
582 orr ip, ip, r6 @ mask in offset bits 31-24
585 ldrcc r7, [r4], #4 @ use branch for delay slot
589 ENDPROC(__fixup_a_pv_table)
591 ENTRY(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}
600 ENDPROC(fixup_pv_table)
603 2: .long __pv_phys_offset
606 .globl __pv_phys_offset
607 .type __pv_phys_offset, %object
610 .size __pv_phys_offset, . - __pv_phys_offset
615 #include "head-common.S"