37d07b72ef
Patch from Nicolas Pitre Since vmlinux.lds.S is preprocessed, we can use the defines already present in asm/memory.h (allowed by patch #3060) for the XIP kernel link address instead of relying on a duplicated Makefile hardcoded value, and also get rid of its dependency on awk to handle it at the same time. While at it let's clean XIP stuff even further and make things clearer in head.S with a nice code reduction. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
534 lines
14 KiB
ArmAsm
534 lines
14 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/config.h>
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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/mach-types.h>
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#include <asm/procinfo.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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#define PROCINFO_MMUFLAGS 8
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#define PROCINFO_INITFUNC 12
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#define MACHINFO_TYPE 0
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#define MACHINFO_PHYSRAM 4
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#define MACHINFO_PHYSIO 8
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#define MACHINFO_PGOFFIO 12
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#define MACHINFO_NAME 16
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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_ADDR. Therefore, we must
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* make sure that KERNEL_RAM_ADDR 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_ADDR >= PAGE_OFFSET + 0x4000.
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*/
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#if (KERNEL_RAM_ADDR & 0xffff) != 0x8000
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#error KERNEL_RAM_ADDR 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_ADDR - 0x4000
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.macro pgtbl, rd
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ldr \rd, =(__virt_to_phys(KERNEL_RAM_ADDR - 0x4000))
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.endm
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#ifdef CONFIG_XIP_KERNEL
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#define TEXTADDR XIP_VIRT_ADDR(CONFIG_XIP_PHYS_ADDR)
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#else
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#define TEXTADDR KERNEL_RAM_ADDR
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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.
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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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__INIT
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.type stext, %function
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ENTRY(stext)
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msr cpsr_c, #PSR_F_BIT | PSR_I_BIT | MODE_SVC @ ensure svc mode
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@ and irqs disabled
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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 __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, __enable_mmu @ return (PIC) address
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add pc, r10, #PROCINFO_INITFUNC
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.type __switch_data, %object
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__switch_data:
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.long __mmap_switched
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.long __data_loc @ r4
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.long __data_start @ r5
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.long __bss_start @ r6
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.long _end @ r7
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.long processor_id @ r4
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.long __machine_arch_type @ r5
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.long cr_alignment @ r6
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.long init_thread_union + THREAD_START_SP @ sp
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/*
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* The following fragment of code is executed with the MMU on, and uses
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* absolute addresses; this is not position independent.
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*
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* r0 = cp#15 control register
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* r1 = machine ID
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* r9 = processor ID
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*/
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.type __mmap_switched, %function
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__mmap_switched:
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adr r3, __switch_data + 4
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ldmia r3!, {r4, r5, r6, r7}
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cmp r4, r5 @ Copy data segment if needed
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1: cmpne r5, r6
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ldrne fp, [r4], #4
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strne fp, [r5], #4
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bne 1b
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mov fp, #0 @ Clear BSS (and zero fp)
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1: cmp r6, r7
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strcc fp, [r6],#4
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bcc 1b
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ldmia r3, {r4, r5, r6, sp}
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str r9, [r4] @ Save processor ID
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str r1, [r5] @ Save machine type
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bic r4, r0, #CR_A @ Clear 'A' bit
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stmia r6, {r0, r4} @ Save control register values
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b start_kernel
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#if defined(CONFIG_SMP)
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.type secondary_startup, #function
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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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msr cpsr_c, #PSR_F_BIT | PSR_I_BIT | MODE_SVC
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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, r6, r13} @ address to jump to after
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sub r4, r4, r5 @ mmu has been enabled
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ldr r4, [r6, r4] @ get secondary_data.pgdir
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adr lr, __enable_mmu @ return address
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add pc, r10, #12 @ initialise processor
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@ (return control reg)
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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, [r6, #4] @ get secondary_data.stack
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mov fp, #0
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b secondary_start_kernel
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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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.type __enable_mmu, %function
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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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/*
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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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.type __turn_mmu_on, %function
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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, r3
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mov pc, r13
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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, r5, r6, r7 corrupted
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* r4 = physical page table address
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*/
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.type __create_page_tables, %function
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__create_page_tables:
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ldr r5, [r8, #MACHINFO_PHYSRAM] @ physram
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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_MMUFLAGS] @ 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, 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. We round TEXTADDR down to the
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* nearest megabyte boundary. It is assumed that
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* the kernel fits within 4 contigous 1MB sections.
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*/
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add r0, r4, #(TEXTADDR & 0xff000000) >> 18 @ start of kernel
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str r3, [r0, #(TEXTADDR & 0x00f00000) >> 18]!
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add r3, r3, #1 << 20
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str r3, [r0, #4]! @ KERNEL + 1MB
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add r3, r3, #1 << 20
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str r3, [r0, #4]! @ KERNEL + 2MB
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add r3, r3, #1 << 20
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str r3, [r0, #4] @ KERNEL + 3MB
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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, r5, r7
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str r6, [r0]
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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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* Mapping 3MB should be plenty.
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*/
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sub r3, r4, r5
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mov r3, r3, lsr #20
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add r0, r0, r3, lsl #2
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add r6, r6, r3, lsl #20
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str r6, [r0], #4
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add r6, r6, #(1 << 20)
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str r6, [r0], #4
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add r6, r6, #(1 << 20)
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str r6, [r0]
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#endif
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#ifdef CONFIG_DEBUG_LL
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bic r7, r7, #0x0c @ turn off cacheable
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@ and bufferable bits
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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, we need to map in
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* the 16550-type serial port for the debug messages
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*/
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teq r1, #MACH_TYPE_NETWINDER
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teqne r1, #MACH_TYPE_CATS
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bne 1f
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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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1:
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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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.ltorg
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/*
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* Exception handling. Something went wrong and we can't proceed. We
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* ought to tell the user, but since we don't have any guarantee that
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* we're even running on the right architecture, we do virtually nothing.
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*
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* If CONFIG_DEBUG_LL is set we try to print out something about the error
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* and hope for the best (useful if bootloader fails to pass a proper
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* machine ID for example).
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*/
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.type __error_p, %function
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__error_p:
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#ifdef CONFIG_DEBUG_LL
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adr r0, str_p1
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bl printascii
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b __error
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str_p1: .asciz "\nError: unrecognized/unsupported processor variant.\n"
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.align
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#endif
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.type __error_a, %function
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__error_a:
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#ifdef CONFIG_DEBUG_LL
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mov r4, r1 @ preserve machine ID
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adr r0, str_a1
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bl printascii
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mov r0, r4
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bl printhex8
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adr r0, str_a2
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bl printascii
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adr r3, 3f
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ldmia r3, {r4, r5, r6} @ get machine desc list
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sub r4, r3, r4 @ get offset between virt&phys
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add r5, r5, r4 @ convert virt addresses to
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add r6, r6, r4 @ physical address space
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1: ldr r0, [r5, #MACHINFO_TYPE] @ get machine type
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bl printhex8
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mov r0, #'\t'
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bl printch
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ldr r0, [r5, #MACHINFO_NAME] @ get machine name
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add r0, r0, r4
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bl printascii
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mov r0, #'\n'
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bl printch
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add r5, r5, #SIZEOF_MACHINE_DESC @ next machine_desc
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cmp r5, r6
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blo 1b
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adr r0, str_a3
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bl printascii
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b __error
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str_a1: .asciz "\nError: unrecognized/unsupported machine ID (r1 = 0x"
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str_a2: .asciz ").\n\nAvailable machine support:\n\nID (hex)\tNAME\n"
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str_a3: .asciz "\nPlease check your kernel config and/or bootloader.\n"
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.align
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#endif
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.type __error, %function
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__error:
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#ifdef CONFIG_ARCH_RPC
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/*
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* Turn the screen red on a error - RiscPC only.
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*/
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mov r0, #0x02000000
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mov r3, #0x11
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orr r3, r3, r3, lsl #8
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orr r3, r3, r3, lsl #16
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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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str r3, [r0], #4
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#endif
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1: mov r0, r0
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b 1b
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/*
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* Read processor ID register (CP#15, CR0), and look up in the linker-built
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* supported processor list. Note that we can't use the absolute addresses
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* for the __proc_info lists since we aren't running with the MMU on
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* (and therefore, we are not in the correct address space). We have to
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* calculate the offset.
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*
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* Returns:
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* r3, r4, r6 corrupted
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* r5 = proc_info pointer in physical address space
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* r9 = cpuid
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*/
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.type __lookup_processor_type, %function
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__lookup_processor_type:
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adr r3, 3f
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ldmda r3, {r5, r6, r9}
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sub r3, r3, r9 @ get offset between virt&phys
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add r5, r5, r3 @ convert virt addresses to
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add r6, r6, r3 @ physical address space
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mrc p15, 0, r9, c0, c0 @ get processor id
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1: ldmia r5, {r3, r4} @ value, mask
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and r4, r4, r9 @ mask wanted bits
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teq r3, r4
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beq 2f
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add r5, r5, #PROC_INFO_SZ @ sizeof(proc_info_list)
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cmp r5, r6
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blo 1b
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mov r5, #0 @ unknown processor
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2: mov pc, lr
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/*
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* This provides a C-API version of the above function.
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*/
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ENTRY(lookup_processor_type)
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stmfd sp!, {r4 - r6, r9, lr}
|
|
bl __lookup_processor_type
|
|
mov r0, r5
|
|
ldmfd sp!, {r4 - r6, r9, pc}
|
|
|
|
/*
|
|
* Look in include/asm-arm/procinfo.h and arch/arm/kernel/arch.[ch] for
|
|
* more information about the __proc_info and __arch_info structures.
|
|
*/
|
|
.long __proc_info_begin
|
|
.long __proc_info_end
|
|
3: .long .
|
|
.long __arch_info_begin
|
|
.long __arch_info_end
|
|
|
|
/*
|
|
* Lookup machine architecture in the linker-build list of architectures.
|
|
* Note that we can't use the absolute addresses for the __arch_info
|
|
* lists since we aren't running with the MMU on (and therefore, we are
|
|
* not in the correct address space). We have to calculate the offset.
|
|
*
|
|
* r1 = machine architecture number
|
|
* Returns:
|
|
* r3, r4, r6 corrupted
|
|
* r5 = mach_info pointer in physical address space
|
|
*/
|
|
.type __lookup_machine_type, %function
|
|
__lookup_machine_type:
|
|
adr r3, 3b
|
|
ldmia r3, {r4, r5, r6}
|
|
sub r3, r3, r4 @ get offset between virt&phys
|
|
add r5, r5, r3 @ convert virt addresses to
|
|
add r6, r6, r3 @ physical address space
|
|
1: ldr r3, [r5, #MACHINFO_TYPE] @ get machine type
|
|
teq r3, r1 @ matches loader number?
|
|
beq 2f @ found
|
|
add r5, r5, #SIZEOF_MACHINE_DESC @ next machine_desc
|
|
cmp r5, r6
|
|
blo 1b
|
|
mov r5, #0 @ unknown machine
|
|
2: mov pc, lr
|
|
|
|
/*
|
|
* This provides a C-API version of the above function.
|
|
*/
|
|
ENTRY(lookup_machine_type)
|
|
stmfd sp!, {r4 - r6, lr}
|
|
mov r1, r0
|
|
bl __lookup_machine_type
|
|
mov r0, r5
|
|
ldmfd sp!, {r4 - r6, pc}
|