244 lines
5.7 KiB
ArmAsm
244 lines
5.7 KiB
ArmAsm
/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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* linux/arch/arm/kernel/head-common.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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#include <asm/assembler.h>
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#define ATAG_CORE 0x54410001
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#define ATAG_CORE_SIZE ((2*4 + 3*4) >> 2)
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#define ATAG_CORE_SIZE_EMPTY ((2*4) >> 2)
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#ifdef CONFIG_CPU_BIG_ENDIAN
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#define OF_DT_MAGIC 0xd00dfeed
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#else
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#define OF_DT_MAGIC 0xedfe0dd0 /* 0xd00dfeed in big-endian */
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#endif
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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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__HEAD
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/* Determine validity of the r2 atags pointer. The heuristic requires
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* that the pointer be aligned, in the first 16k of physical RAM and
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* that the ATAG_CORE marker is first and present. If CONFIG_OF_FLATTREE
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* is selected, then it will also accept a dtb pointer. Future revisions
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* of this function may be more lenient with the physical address and
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* may also be able to move the ATAGS block if necessary.
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*
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* Returns:
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* r2 either valid atags pointer, valid dtb pointer, or zero
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* r5, r6 corrupted
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*/
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__vet_atags:
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tst r2, #0x3 @ aligned?
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bne 1f
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ldr r5, [r2, #0]
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#ifdef CONFIG_OF_FLATTREE
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ldr r6, =OF_DT_MAGIC @ is it a DTB?
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cmp r5, r6
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beq 2f
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#endif
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cmp r5, #ATAG_CORE_SIZE @ is first tag ATAG_CORE?
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cmpne r5, #ATAG_CORE_SIZE_EMPTY
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bne 1f
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ldr r5, [r2, #4]
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ldr r6, =ATAG_CORE
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cmp r5, r6
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bne 1f
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2: ret lr @ atag/dtb pointer is ok
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1: mov r2, #0
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ret lr
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ENDPROC(__vet_atags)
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/*
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* The following fragment of code is executed with the MMU on in MMU mode,
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* and uses absolute addresses; this is not position independent.
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*
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* r0 = cp#15 control register (exc_ret for M-class)
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* r1 = machine ID
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* r2 = atags/dtb pointer
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* r9 = processor ID
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*/
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__INIT
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__mmap_switched:
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mov r7, r1
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mov r8, r2
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mov r10, r0
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adr r4, __mmap_switched_data
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mov fp, #0
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#if defined(CONFIG_XIP_DEFLATED_DATA)
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ARM( ldr sp, [r4], #4 )
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THUMB( ldr sp, [r4] )
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THUMB( add r4, #4 )
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bl __inflate_kernel_data @ decompress .data to RAM
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teq r0, #0
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bne __error
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#elif defined(CONFIG_XIP_KERNEL)
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ARM( ldmia r4!, {r0, r1, r2, sp} )
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THUMB( ldmia r4!, {r0, r1, r2, r3} )
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THUMB( mov sp, r3 )
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sub r2, r2, r1
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bl memcpy @ copy .data to RAM
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#endif
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ARM( ldmia r4!, {r0, r1, sp} )
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THUMB( ldmia r4!, {r0, r1, r3} )
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THUMB( mov sp, r3 )
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sub r2, r1, r0
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mov r1, #0
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bl memset @ clear .bss
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ldmia r4, {r0, r1, r2, r3}
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str r9, [r0] @ Save processor ID
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str r7, [r1] @ Save machine type
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str r8, [r2] @ Save atags pointer
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cmp r3, #0
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strne r10, [r3] @ Save control register values
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mov lr, #0
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b start_kernel
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ENDPROC(__mmap_switched)
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.align 2
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.type __mmap_switched_data, %object
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__mmap_switched_data:
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#ifdef CONFIG_XIP_KERNEL
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#ifndef CONFIG_XIP_DEFLATED_DATA
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.long _sdata @ r0
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.long __data_loc @ r1
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.long _edata_loc @ r2
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#endif
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.long __bss_stop @ sp (temporary stack in .bss)
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#endif
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.long __bss_start @ r0
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.long __bss_stop @ r1
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.long init_thread_union + THREAD_START_SP @ sp
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.long processor_id @ r0
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.long __machine_arch_type @ r1
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.long __atags_pointer @ r2
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#ifdef CONFIG_CPU_CP15
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.long cr_alignment @ r3
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#else
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M_CLASS(.long exc_ret) @ r3
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AR_CLASS(.long 0) @ r3
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#endif
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.size __mmap_switched_data, . - __mmap_switched_data
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__FINIT
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.text
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/*
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* This provides a C-API version of __lookup_processor_type
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*/
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ENTRY(lookup_processor_type)
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stmfd sp!, {r4 - r6, r9, lr}
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mov r9, r0
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bl __lookup_processor_type
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mov r0, r5
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ldmfd sp!, {r4 - r6, r9, pc}
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ENDPROC(lookup_processor_type)
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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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* r9 = cpuid
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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 (preserved)
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*/
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__lookup_processor_type:
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adr r3, __lookup_processor_type_data
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ldmia r3, {r4 - r6}
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sub r3, r3, r4 @ 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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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: ret lr
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ENDPROC(__lookup_processor_type)
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/*
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* Look in <asm/procinfo.h> for information about the __proc_info structure.
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*/
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.align 2
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.type __lookup_processor_type_data, %object
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__lookup_processor_type_data:
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.long .
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.long __proc_info_begin
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.long __proc_info_end
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.size __lookup_processor_type_data, . - __lookup_processor_type_data
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__error_lpae:
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#ifdef CONFIG_DEBUG_LL
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adr r0, str_lpae
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bl printascii
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b __error
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str_lpae: .asciz "\nError: Kernel with LPAE support, but CPU does not support LPAE.\n"
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#else
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b __error
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#endif
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.align
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ENDPROC(__error_lpae)
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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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mov r0, r9
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bl printhex8
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adr r0, str_p2
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bl printascii
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b __error
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str_p1: .asciz "\nError: unrecognized/unsupported processor variant (0x"
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str_p2: .asciz ").\n"
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.align
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#endif
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ENDPROC(__error_p)
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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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ENDPROC(__error)
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