diff options
Diffstat (limited to 'arch/powerpc/boot/crt0.S')
| -rw-r--r-- | arch/powerpc/boot/crt0.S | 116 |
1 files changed, 74 insertions, 42 deletions
diff --git a/arch/powerpc/boot/crt0.S b/arch/powerpc/boot/crt0.S index f1c4dfc..0f7428a 100644 --- a/arch/powerpc/boot/crt0.S +++ b/arch/powerpc/boot/crt0.S @@ -6,16 +6,28 @@ * 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 and is packaged as ELF32. + * 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 */ + /* 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 _zimage_start, 0, 0, 0 + .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 @@ -24,37 +36,65 @@ _zimage_start: _zimage_start_lib: /* Work out the offset between the address we were linked at and the address where we're running. */ - bl 1f -1: mflr r0 - lis r9,1b@ha - addi r9,r9,1b@l - subf. r0,r9,r0 - beq 3f /* if running at same address as linked */ + 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 .got2 section contains a list of addresses, so add - the address offset onto each entry. */ - lis r9,__got2_start@ha - addi r9,r9,__got2_start@l - lis r8,__got2_end@ha - addi r8,r8,__got2_end@l - subf. r8,r9,r8 + /* 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 - srwi. r8,r8,2 - mtctr r8 - add r9,r0,r9 -2: lwz r8,0(r9) - add r8,r8,r0 - stw r8,0(r9) - addi r9,r9,4 + 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: lis r9,_start@ha - addi r9,r9,_start@l - add r9,r0,r9 - lis r8,_etext@ha - addi r8,r8,_etext@l - add r8,r0,r8 +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 @@ -64,27 +104,19 @@ _zimage_start_lib: isync /* Clear the BSS */ - lis r9,__bss_start@ha - addi r9,r9,__bss_start@l - add r9,r0,r9 - lis r8,_end@ha - addi r8,r8,_end@l - add r8,r0,r8 - li r10,0 -5: stw r10,0(r9) + 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 */ -.weak _platform_stack_top - lis r8,_platform_stack_top@ha - addi r8,r8,_platform_stack_top@l + lwz r8,p_pstack-p_base(r10) cmpwi r8,0 beq 6f - add r8,r0,r8 lwz r1,0(r8) - add r1,r0,r1 li r0,0 stwu r0,-16(r1) /* establish a stack frame */ 6: |
