diff options
Diffstat (limited to 'arch/powerpc/boot/crt0.S')
| -rw-r--r-- | arch/powerpc/boot/crt0.S | 128 |
1 files changed, 128 insertions, 0 deletions
diff --git a/arch/powerpc/boot/crt0.S b/arch/powerpc/boot/crt0.S new file mode 100644 index 00000000..0f7428a3 --- /dev/null +++ b/arch/powerpc/boot/crt0.S @@ -0,0 +1,128 @@ +/* + * 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 |