* 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
_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
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:
projects / ~andy / linux / blobdiff