/*
* Code to process dynamic relocations for PPC32.
*
* Copyrights (C) IBM Corporation, 2011.
* Author: Suzuki Poulose <suzuki@in.ibm.com>
*
* - Based on ppc64 code - reloc_64.S
*
* 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.
*/
#include <asm/ppc_asm.h>
/* Dynamic section table entry tags */
DT_RELA = 7 /* Tag for Elf32_Rela section */
DT_RELASZ = 8 /* Size of the Rela relocs */
DT_RELAENT = 9 /* Size of one Rela reloc entry */
STN_UNDEF = 0 /* Undefined symbol index */
STB_LOCAL = 0 /* Local binding for the symbol */
R_PPC_ADDR16_LO = 4 /* Lower half of (S+A) */
R_PPC_ADDR16_HI = 5 /* Upper half of (S+A) */
R_PPC_ADDR16_HA = 6 /* High Adjusted (S+A) */
R_PPC_RELATIVE = 22
/*
* r3 = desired final address
*/
_GLOBAL(relocate)
mflr r0 /* Save our LR */
bl 0f /* Find our current runtime address */
0: mflr r12 /* Make it accessible */
mtlr r0
lwz r11, (p_dyn - 0b)(r12)
add r11, r11, r12 /* runtime address of .dynamic section */
lwz r9, (p_rela - 0b)(r12)
add r9, r9, r12 /* runtime address of .rela.dyn section */
lwz r10, (p_st - 0b)(r12)
add r10, r10, r12 /* runtime address of _stext section */
lwz r13, (p_sym - 0b)(r12)
add r13, r13, r12 /* runtime address of .dynsym section */
/*
* Scan the dynamic section for RELA, RELASZ entries
*/
li r6, 0
li r7, 0
li r8, 0
1: lwz r5, 0(r11) /* ELF_Dyn.d_tag */
cmpwi r5, 0 /* End of ELF_Dyn[] */
beq eodyn
cmpwi r5, DT_RELA
bne relasz
lwz r7, 4(r11) /* r7 = rela.link */
b skip
relasz:
cmpwi r5, DT_RELASZ
bne relaent
lwz r8, 4(r11) /* r8 = Total Rela relocs size */
b skip
relaent:
cmpwi r5, DT_RELAENT
bne skip
lwz r6, 4(r11) /* r6 = Size of one Rela reloc */
skip:
addi r11, r11, 8
b 1b
eodyn: /* End of Dyn Table scan */
/* Check if we have found all the entries */
cmpwi r7, 0
beq done
cmpwi r8, 0
beq done
cmpwi r6, 0
beq done
/*
* Work out the current offset from the link time address of .rela
* section.
* cur_offset[r7] = rela.run[r9] - rela.link [r7]
* _stext.link[r12] = _stext.run[r10] - cur_offset[r7]
* final_offset[r3] = _stext.final[r3] - _stext.link[r12]
*/
subf r7, r7, r9 /* cur_offset */
subf r12, r7, r10
subf r3, r12, r3 /* final_offset */
subf r8, r6, r8 /* relaz -= relaent */
/*
* Scan through the .rela table and process each entry
* r9 - points to the current .rela table entry
* r13 - points to the symbol table
*/
/*
* Check if we have a relocation based on symbol
* r5 will hold the value of the symbol.
*/
applyrela:
lwz r4, 4(r9) /* r4 = rela.r_info */
srwi r5, r4, 8 /* ELF32_R_SYM(r_info) */
cmpwi r5, STN_UNDEF /* sym == STN_UNDEF ? */
beq get_type /* value = 0 */
/* Find the value of the symbol at index(r5) */
slwi r5, r5, 4 /* r5 = r5 * sizeof(Elf32_Sym) */
add r12, r13, r5 /* r12 = &__dyn_sym[Index] */
/*
* GNU ld has a bug, where dynamic relocs based on
* STB_LOCAL symbols, the value should be assumed
* to be zero. - Alan Modra
*/
/* XXX: Do we need to check if we are using GNU ld ? */
lbz r5, 12(r12) /* r5 = dyn_sym[Index].st_info */
extrwi r5, r5, 4, 24 /* r5 = ELF32_ST_BIND(r5) */
cmpwi r5, STB_LOCAL /* st_value = 0, ld bug */
beq get_type /* We have r5 = 0 */
lwz r5, 4(r12) /* r5 = __dyn_sym[Index].st_value */
get_type:
/* Load the relocation type to r4 */
extrwi r4, r4, 8, 24 /* r4 = ELF32_R_TYPE(r_info) = ((char*)r4)[3] */
/* R_PPC_RELATIVE */
cmpwi r4, R_PPC_RELATIVE
bne hi16
lwz r4, 0(r9) /* r_offset */
lwz r0, 8(r9) /* r_addend */
add r0, r0, r3 /* final addend */
stwx r0, r4, r7 /* memory[r4+r7]) = (u32)r0 */
b nxtrela /* continue */
/* R_PPC_ADDR16_HI */
hi16:
cmpwi r4, R_PPC_ADDR16_HI
bne ha16
lwz r4, 0(r9) /* r_offset */
lwz r0, 8(r9) /* r_addend */
add r0, r0, r3
add r0, r0, r5 /* r0 = (S+A+Offset) */
extrwi r0, r0, 16, 0 /* r0 = (r0 >> 16) */
b store_half
/* R_PPC_ADDR16_HA */
ha16:
cmpwi r4, R_PPC_ADDR16_HA
bne lo16
lwz r4, 0(r9) /* r_offset */
lwz r0, 8(r9) /* r_addend */
add r0, r0, r3
add r0, r0, r5 /* r0 = (S+A+Offset) */
extrwi r5, r0, 1, 16 /* Extract bit 16 */
extrwi r0, r0, 16, 0 /* r0 = (r0 >> 16) */
add r0, r0, r5 /* Add it to r0 */
b store_half
/* R_PPC_ADDR16_LO */
lo16:
cmpwi r4, R_PPC_ADDR16_LO
bne unknown_type
lwz r4, 0(r9) /* r_offset */
lwz r0, 8(r9) /* r_addend */
add r0, r0, r3
add r0, r0, r5 /* r0 = (S+A+Offset) */
extrwi r0, r0, 16, 16 /* r0 &= 0xffff */
/* Fall through to */
/* Store half word */
store_half:
sthx r0, r4, r7 /* memory[r4+r7] = (u16)r0 */
nxtrela:
/*
* We have to flush the modified instructions to the
* main storage from the d-cache. And also, invalidate the
* cached instructions in i-cache which has been modified.
*
* We delay the sync / isync operation till the end, since
* we won't be executing the modified instructions until
* we return from here.
*/
dcbst r4,r7
sync /* Ensure the data is flushed before icbi */
icbi r4,r7
unknown_type:
cmpwi r8, 0 /* relasz = 0 ? */
ble done
add r9, r9, r6 /* move to next entry in the .rela table */
subf r8, r6, r8 /* relasz -= relaent */
b applyrela
done:
sync /* Wait for the flush to finish */
isync /* Discard prefetched instructions */
blr
p_dyn: .long __dynamic_start - 0b
p_rela: .long __rela_dyn_start - 0b
p_sym: .long __dynamic_symtab - 0b
p_st: .long _stext - 0b
