129 lines
3.1 KiB
ArmAsm
129 lines
3.1 KiB
ArmAsm
/*
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* Copyright (C) Paul Mackerras 1997.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*
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* NOTE: this code runs in 32 bit mode, is position-independent,
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* and is packaged as ELF32.
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*/
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#include "ppc_asm.h"
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.text
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/* A procedure descriptor used when booting this as a COFF file.
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* When making COFF, this comes first in the link and we're
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* linked at 0x500000.
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*/
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.globl _zimage_start_opd
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_zimage_start_opd:
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.long 0x500000, 0, 0, 0
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p_start: .long _start
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p_etext: .long _etext
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p_bss_start: .long __bss_start
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p_end: .long _end
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.weak _platform_stack_top
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p_pstack: .long _platform_stack_top
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.weak _zimage_start
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.globl _zimage_start
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_zimage_start:
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.globl _zimage_start_lib
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_zimage_start_lib:
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/* Work out the offset between the address we were linked at
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and the address where we're running. */
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bl .+4
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p_base: mflr r10 /* r10 now points to runtime addr of p_base */
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/* grab the link address of the dynamic section in r11 */
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addis r11,r10,(_GLOBAL_OFFSET_TABLE_-p_base)@ha
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lwz r11,(_GLOBAL_OFFSET_TABLE_-p_base)@l(r11)
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cmpwi r11,0
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beq 3f /* if not linked -pie */
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/* get the runtime address of the dynamic section in r12 */
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.weak __dynamic_start
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addis r12,r10,(__dynamic_start-p_base)@ha
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addi r12,r12,(__dynamic_start-p_base)@l
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subf r11,r11,r12 /* runtime - linktime offset */
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/* The dynamic section contains a series of tagged entries.
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* We need the RELA and RELACOUNT entries. */
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RELA = 7
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RELACOUNT = 0x6ffffff9
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li r9,0
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li r0,0
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9: lwz r8,0(r12) /* get tag */
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cmpwi r8,0
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beq 10f /* end of list */
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cmpwi r8,RELA
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bne 11f
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lwz r9,4(r12) /* get RELA pointer in r9 */
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b 12f
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11: addis r8,r8,(-RELACOUNT)@ha
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cmpwi r8,RELACOUNT@l
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bne 12f
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lwz r0,4(r12) /* get RELACOUNT value in r0 */
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12: addi r12,r12,8
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b 9b
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/* The relocation section contains a list of relocations.
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* We now do the R_PPC_RELATIVE ones, which point to words
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* which need to be initialized with addend + offset.
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* The R_PPC_RELATIVE ones come first and there are RELACOUNT
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* of them. */
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10: /* skip relocation if we don't have both */
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cmpwi r0,0
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beq 3f
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cmpwi r9,0
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beq 3f
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add r9,r9,r11 /* Relocate RELA pointer */
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mtctr r0
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2: lbz r0,4+3(r9) /* ELF32_R_INFO(reloc->r_info) */
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cmpwi r0,22 /* R_PPC_RELATIVE */
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bne 3f
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lwz r12,0(r9) /* reloc->r_offset */
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lwz r0,8(r9) /* reloc->r_addend */
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add r0,r0,r11
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stwx r0,r11,r12
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addi r9,r9,12
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bdnz 2b
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/* Do a cache flush for our text, in case the loader didn't */
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3: lwz r9,p_start-p_base(r10) /* note: these are relocated now */
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lwz r8,p_etext-p_base(r10)
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4: dcbf r0,r9
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icbi r0,r9
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addi r9,r9,0x20
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cmplw cr0,r9,r8
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blt 4b
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sync
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isync
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/* Clear the BSS */
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lwz r9,p_bss_start-p_base(r10)
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lwz r8,p_end-p_base(r10)
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li r0,0
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5: stw r0,0(r9)
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addi r9,r9,4
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cmplw cr0,r9,r8
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blt 5b
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/* Possibly set up a custom stack */
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lwz r8,p_pstack-p_base(r10)
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cmpwi r8,0
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beq 6f
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lwz r1,0(r8)
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li r0,0
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stwu r0,-16(r1) /* establish a stack frame */
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6:
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/* Call platform_init() */
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bl platform_init
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/* Call start */
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b start
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