1/* 2 * Code to process dynamic relocations in the kernel. 3 * 4 * Copyright 2008 Paul Mackerras, IBM Corp. 5 * 6 * This program is free software; you can redistribute it and/or 7 * modify it under the terms of the GNU General Public License 8 * as published by the Free Software Foundation; either version 9 * 2 of the License, or (at your option) any later version. 10 */ 11 12#include <asm/ppc_asm.h> 13 14RELA = 7 15RELACOUNT = 0x6ffffff9 16R_PPC64_RELATIVE = 22 17 18/* 19 * r3 = desired final address of kernel 20 */ 21_GLOBAL(relocate) 22 mflr r0 23 bcl 20,31,$+4 240: mflr r12 /* r12 has runtime addr of label 0 */ 25 mtlr r0 26 ld r11,(p_dyn - 0b)(r12) 27 add r11,r11,r12 /* r11 has runtime addr of .dynamic section */ 28 ld r9,(p_rela - 0b)(r12) 29 add r9,r9,r12 /* r9 has runtime addr of .rela.dyn section */ 30 ld r10,(p_st - 0b)(r12) 31 add r10,r10,r12 /* r10 has runtime addr of _stext */ 32 33 /* 34 * Scan the dynamic section for the RELA and RELACOUNT entries. 35 */ 36 li r7,0 37 li r8,0 381: ld r6,0(r11) /* get tag */ 39 cmpdi r6,0 40 beq 4f /* end of list */ 41 cmpdi r6,RELA 42 bne 2f 43 ld r7,8(r11) /* get RELA pointer in r7 */ 44 b 3f 452: addis r6,r6,(-RELACOUNT)@ha 46 cmpdi r6,RELACOUNT@l 47 bne 3f 48 ld r8,8(r11) /* get RELACOUNT value in r8 */ 493: addi r11,r11,16 50 b 1b 514: cmpdi r7,0 /* check we have both RELA and RELACOUNT */ 52 cmpdi cr1,r8,0 53 beq 6f 54 beq cr1,6f 55 56 /* 57 * Work out linktime address of _stext and hence the 58 * relocation offset to be applied. 59 * cur_offset [r7] = rela.run [r9] - rela.link [r7] 60 * _stext.link [r10] = _stext.run [r10] - cur_offset [r7] 61 * final_offset [r3] = _stext.final [r3] - _stext.link [r10] 62 */ 63 subf r7,r7,r9 /* cur_offset */ 64 subf r10,r7,r10 65 subf r3,r10,r3 /* final_offset */ 66 67 /* 68 * Run through the list of relocations and process the 69 * R_PPC64_RELATIVE ones. 70 */ 71 mtctr r8 725: ld r0,8(9) /* ELF64_R_TYPE(reloc->r_info) */ 73 cmpdi r0,R_PPC64_RELATIVE 74 bne 6f 75 ld r6,0(r9) /* reloc->r_offset */ 76 ld r0,16(r9) /* reloc->r_addend */ 77 add r0,r0,r3 78 stdx r0,r7,r6 79 addi r9,r9,24 80 bdnz 5b 81 826: blr 83 84.balign 8 85p_dyn: .llong __dynamic_start - 0b 86p_rela: .llong __rela_dyn_start - 0b 87p_st: .llong _stext - 0b 88 89