arch/powerpc/kernel/reloc_64.S

   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
  14 RELA = 7
  15 RELACOUNT = 0x6ffffff9
  16 R_PPC64_RELATIVE = 22
  17
  18 /*
  19  * r3 = desired final address of kernel
  20  */
  21 _GLOBAL(relocate)
  22         mflr    r0
  23         bcl     20,31,$+4
  24 0:      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
  38 1:      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
  45 2:      addis   r6,r6,(-RELACOUNT)@ha
  46         cmpdi   r6,RELACOUNT@l
  47         bne     3f
  48         ld      r8,8(r11)       /* get RELACOUNT value in r8 */
  49 3:      addi    r11,r11,16
  50         b       1b
  51 4:      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
  72 5:      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
  82 6:      blr
  83
  84 .balign 8
  85 p_dyn:  .llong  __dynamic_start - 0b
  86 p_rela: .llong  __rela_dyn_start - 0b
  87 p_st:   .llong  _stext - 0b
  88