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