b86040a59f
This patch implements the ARM/Thumb-2 unified kernel start-up and exception handling code. Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
337 lines
9.0 KiB
ArmAsm
337 lines
9.0 KiB
ArmAsm
/*
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* linux/arch/arm/kernel/head.S
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*
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* Copyright (C) 1994-2002 Russell King
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* Copyright (c) 2003 ARM Limited
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* All Rights Reserved
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* Kernel startup code for all 32-bit CPUs
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*/
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#include <linux/linkage.h>
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#include <linux/init.h>
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#include <asm/assembler.h>
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#include <asm/domain.h>
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#include <asm/ptrace.h>
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#include <asm/asm-offsets.h>
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#include <asm/memory.h>
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#include <asm/thread_info.h>
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#include <asm/system.h>
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#if (PHYS_OFFSET & 0x001fffff)
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#error "PHYS_OFFSET must be at an even 2MiB boundary!"
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#endif
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#define KERNEL_RAM_VADDR (PAGE_OFFSET + TEXT_OFFSET)
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#define KERNEL_RAM_PADDR (PHYS_OFFSET + TEXT_OFFSET)
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/*
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* swapper_pg_dir is the virtual address of the initial page table.
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* We place the page tables 16K below KERNEL_RAM_VADDR. Therefore, we must
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* make sure that KERNEL_RAM_VADDR is correctly set. Currently, we expect
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* the least significant 16 bits to be 0x8000, but we could probably
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* relax this restriction to KERNEL_RAM_VADDR >= PAGE_OFFSET + 0x4000.
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*/
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#if (KERNEL_RAM_VADDR & 0xffff) != 0x8000
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#error KERNEL_RAM_VADDR must start at 0xXXXX8000
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#endif
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.globl swapper_pg_dir
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.equ swapper_pg_dir, KERNEL_RAM_VADDR - 0x4000
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.macro pgtbl, rd
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ldr \rd, =(KERNEL_RAM_PADDR - 0x4000)
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.endm
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#ifdef CONFIG_XIP_KERNEL
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#define KERNEL_START XIP_VIRT_ADDR(CONFIG_XIP_PHYS_ADDR)
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#define KERNEL_END _edata_loc
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#else
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#define KERNEL_START KERNEL_RAM_VADDR
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#define KERNEL_END _end
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#endif
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/*
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* Kernel startup entry point.
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* ---------------------------
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*
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* This is normally called from the decompressor code. The requirements
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* are: MMU = off, D-cache = off, I-cache = dont care, r0 = 0,
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* r1 = machine nr, r2 = atags pointer.
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*
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* This code is mostly position independent, so if you link the kernel at
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* 0xc0008000, you call this at __pa(0xc0008000).
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*
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* See linux/arch/arm/tools/mach-types for the complete list of machine
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* numbers for r1.
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*
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* We're trying to keep crap to a minimum; DO NOT add any machine specific
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* crap here - that's what the boot loader (or in extreme, well justified
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* circumstances, zImage) is for.
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*/
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.section ".text.head", "ax"
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ENTRY(stext)
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setmode PSR_F_BIT | PSR_I_BIT | SVC_MODE, r9 @ ensure svc mode
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@ and irqs disabled
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mrc p15, 0, r9, c0, c0 @ get processor id
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bl __lookup_processor_type @ r5=procinfo r9=cpuid
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movs r10, r5 @ invalid processor (r5=0)?
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beq __error_p @ yes, error 'p'
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bl __lookup_machine_type @ r5=machinfo
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movs r8, r5 @ invalid machine (r5=0)?
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beq __error_a @ yes, error 'a'
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bl __vet_atags
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bl __create_page_tables
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/*
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* The following calls CPU specific code in a position independent
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* manner. See arch/arm/mm/proc-*.S for details. r10 = base of
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* xxx_proc_info structure selected by __lookup_machine_type
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* above. On return, the CPU will be ready for the MMU to be
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* turned on, and r0 will hold the CPU control register value.
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*/
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ldr r13, __switch_data @ address to jump to after
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@ mmu has been enabled
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adr lr, BSYM(__enable_mmu) @ return (PIC) address
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ARM( add pc, r10, #PROCINFO_INITFUNC )
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THUMB( add r12, r10, #PROCINFO_INITFUNC )
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THUMB( mov pc, r12 )
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ENDPROC(stext)
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#if defined(CONFIG_SMP)
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ENTRY(secondary_startup)
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/*
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* Common entry point for secondary CPUs.
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*
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* Ensure that we're in SVC mode, and IRQs are disabled. Lookup
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* the processor type - there is no need to check the machine type
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* as it has already been validated by the primary processor.
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*/
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setmode PSR_F_BIT | PSR_I_BIT | SVC_MODE, r9
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mrc p15, 0, r9, c0, c0 @ get processor id
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bl __lookup_processor_type
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movs r10, r5 @ invalid processor?
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moveq r0, #'p' @ yes, error 'p'
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beq __error
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/*
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* Use the page tables supplied from __cpu_up.
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*/
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adr r4, __secondary_data
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ldmia r4, {r5, r7, r12} @ address to jump to after
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sub r4, r4, r5 @ mmu has been enabled
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ldr r4, [r7, r4] @ get secondary_data.pgdir
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adr lr, BSYM(__enable_mmu) @ return address
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mov r13, r12 @ __secondary_switched address
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ARM( add pc, r10, #PROCINFO_INITFUNC ) @ initialise processor
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@ (return control reg)
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THUMB( add r12, r10, #PROCINFO_INITFUNC )
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THUMB( mov pc, r12 )
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ENDPROC(secondary_startup)
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/*
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* r6 = &secondary_data
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*/
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ENTRY(__secondary_switched)
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ldr sp, [r7, #4] @ get secondary_data.stack
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mov fp, #0
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b secondary_start_kernel
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ENDPROC(__secondary_switched)
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.type __secondary_data, %object
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__secondary_data:
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.long .
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.long secondary_data
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.long __secondary_switched
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#endif /* defined(CONFIG_SMP) */
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/*
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* Setup common bits before finally enabling the MMU. Essentially
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* this is just loading the page table pointer and domain access
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* registers.
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*/
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__enable_mmu:
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#ifdef CONFIG_ALIGNMENT_TRAP
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orr r0, r0, #CR_A
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#else
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bic r0, r0, #CR_A
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#endif
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#ifdef CONFIG_CPU_DCACHE_DISABLE
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bic r0, r0, #CR_C
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#endif
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#ifdef CONFIG_CPU_BPREDICT_DISABLE
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bic r0, r0, #CR_Z
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#endif
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#ifdef CONFIG_CPU_ICACHE_DISABLE
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bic r0, r0, #CR_I
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#endif
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mov r5, #(domain_val(DOMAIN_USER, DOMAIN_MANAGER) | \
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domain_val(DOMAIN_KERNEL, DOMAIN_MANAGER) | \
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domain_val(DOMAIN_TABLE, DOMAIN_MANAGER) | \
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domain_val(DOMAIN_IO, DOMAIN_CLIENT))
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mcr p15, 0, r5, c3, c0, 0 @ load domain access register
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mcr p15, 0, r4, c2, c0, 0 @ load page table pointer
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b __turn_mmu_on
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ENDPROC(__enable_mmu)
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/*
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* Enable the MMU. This completely changes the structure of the visible
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* memory space. You will not be able to trace execution through this.
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* If you have an enquiry about this, *please* check the linux-arm-kernel
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* mailing list archives BEFORE sending another post to the list.
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*
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* r0 = cp#15 control register
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* r13 = *virtual* address to jump to upon completion
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*
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* other registers depend on the function called upon completion
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*/
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.align 5
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__turn_mmu_on:
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mov r0, r0
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mcr p15, 0, r0, c1, c0, 0 @ write control reg
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mrc p15, 0, r3, c0, c0, 0 @ read id reg
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mov r3, r3
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mov r3, r13
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mov pc, r3
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ENDPROC(__turn_mmu_on)
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/*
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* Setup the initial page tables. We only setup the barest
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* amount which are required to get the kernel running, which
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* generally means mapping in the kernel code.
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*
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* r8 = machinfo
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* r9 = cpuid
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* r10 = procinfo
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*
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* Returns:
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* r0, r3, r6, r7 corrupted
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* r4 = physical page table address
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*/
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__create_page_tables:
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pgtbl r4 @ page table address
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/*
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* Clear the 16K level 1 swapper page table
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*/
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mov r0, r4
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mov r3, #0
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add r6, r0, #0x4000
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1: str r3, [r0], #4
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str r3, [r0], #4
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str r3, [r0], #4
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str r3, [r0], #4
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teq r0, r6
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bne 1b
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ldr r7, [r10, #PROCINFO_MM_MMUFLAGS] @ mm_mmuflags
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/*
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* Create identity mapping for first MB of kernel to
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* cater for the MMU enable. This identity mapping
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* will be removed by paging_init(). We use our current program
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* counter to determine corresponding section base address.
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*/
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mov r6, pc
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mov r6, r6, lsr #20 @ start of kernel section
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orr r3, r7, r6, lsl #20 @ flags + kernel base
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str r3, [r4, r6, lsl #2] @ identity mapping
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/*
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* Now setup the pagetables for our kernel direct
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* mapped region.
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*/
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add r0, r4, #(KERNEL_START & 0xff000000) >> 18
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str r3, [r0, #(KERNEL_START & 0x00f00000) >> 18]!
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ldr r6, =(KERNEL_END - 1)
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add r0, r0, #4
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add r6, r4, r6, lsr #18
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1: cmp r0, r6
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add r3, r3, #1 << 20
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strls r3, [r0], #4
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bls 1b
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#ifdef CONFIG_XIP_KERNEL
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/*
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* Map some ram to cover our .data and .bss areas.
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*/
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orr r3, r7, #(KERNEL_RAM_PADDR & 0xff000000)
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.if (KERNEL_RAM_PADDR & 0x00f00000)
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orr r3, r3, #(KERNEL_RAM_PADDR & 0x00f00000)
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.endif
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add r0, r4, #(KERNEL_RAM_VADDR & 0xff000000) >> 18
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str r3, [r0, #(KERNEL_RAM_VADDR & 0x00f00000) >> 18]!
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ldr r6, =(_end - 1)
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add r0, r0, #4
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add r6, r4, r6, lsr #18
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1: cmp r0, r6
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add r3, r3, #1 << 20
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strls r3, [r0], #4
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bls 1b
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#endif
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/*
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* Then map first 1MB of ram in case it contains our boot params.
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*/
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add r0, r4, #PAGE_OFFSET >> 18
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orr r6, r7, #(PHYS_OFFSET & 0xff000000)
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.if (PHYS_OFFSET & 0x00f00000)
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orr r6, r6, #(PHYS_OFFSET & 0x00f00000)
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.endif
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str r6, [r0]
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#ifdef CONFIG_DEBUG_LL
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ldr r7, [r10, #PROCINFO_IO_MMUFLAGS] @ io_mmuflags
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/*
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* Map in IO space for serial debugging.
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* This allows debug messages to be output
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* via a serial console before paging_init.
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*/
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ldr r3, [r8, #MACHINFO_PGOFFIO]
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add r0, r4, r3
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rsb r3, r3, #0x4000 @ PTRS_PER_PGD*sizeof(long)
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cmp r3, #0x0800 @ limit to 512MB
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movhi r3, #0x0800
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add r6, r0, r3
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ldr r3, [r8, #MACHINFO_PHYSIO]
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orr r3, r3, r7
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1: str r3, [r0], #4
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add r3, r3, #1 << 20
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teq r0, r6
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bne 1b
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#if defined(CONFIG_ARCH_NETWINDER) || defined(CONFIG_ARCH_CATS)
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/*
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* If we're using the NetWinder or CATS, we also need to map
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* in the 16550-type serial port for the debug messages
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*/
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add r0, r4, #0xff000000 >> 18
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orr r3, r7, #0x7c000000
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str r3, [r0]
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#endif
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#ifdef CONFIG_ARCH_RPC
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/*
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* Map in screen at 0x02000000 & SCREEN2_BASE
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* Similar reasons here - for debug. This is
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* only for Acorn RiscPC architectures.
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*/
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add r0, r4, #0x02000000 >> 18
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orr r3, r7, #0x02000000
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str r3, [r0]
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add r0, r4, #0xd8000000 >> 18
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str r3, [r0]
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#endif
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#endif
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mov pc, lr
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ENDPROC(__create_page_tables)
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.ltorg
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#include "head-common.S"
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