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https://github.com/torvalds/linux
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348c2298a6
For an unknown relocation type since the value of r4 is just the 8bit
relocation type, the sum of r4 and r7 may yield an invalid memory
address. For example:
In normal case:
r4 = c00xxxxx
r7 = 40000000
r4 + r7 = 000xxxxx
For an unknown relocation type:
r4 = 000000xx
r7 = 40000000
r4 + r7 = 400000xx
400000xx is an invalid memory address for a board which has just
512M memory.
And for operations such as dcbst or icbi may cause bus error for an
invalid memory address on some platforms and then cause the board
reset. So we should skip the flush/invalidate the d/icache for
an unknown relocation type.
Signed-off-by: Kevin Hao <haokexin@gmail.com>
Acked-by: Suzuki K. Poulose <suzuki@in.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
209 lines
5.4 KiB
ArmAsm
209 lines
5.4 KiB
ArmAsm
/*
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* Code to process dynamic relocations for PPC32.
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*
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* Copyrights (C) IBM Corporation, 2011.
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* Author: Suzuki Poulose <suzuki@in.ibm.com>
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*
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* - Based on ppc64 code - reloc_64.S
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#include <asm/ppc_asm.h>
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/* Dynamic section table entry tags */
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DT_RELA = 7 /* Tag for Elf32_Rela section */
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DT_RELASZ = 8 /* Size of the Rela relocs */
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DT_RELAENT = 9 /* Size of one Rela reloc entry */
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STN_UNDEF = 0 /* Undefined symbol index */
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STB_LOCAL = 0 /* Local binding for the symbol */
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R_PPC_ADDR16_LO = 4 /* Lower half of (S+A) */
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R_PPC_ADDR16_HI = 5 /* Upper half of (S+A) */
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R_PPC_ADDR16_HA = 6 /* High Adjusted (S+A) */
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R_PPC_RELATIVE = 22
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/*
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* r3 = desired final address
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*/
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_GLOBAL(relocate)
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mflr r0 /* Save our LR */
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bl 0f /* Find our current runtime address */
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0: mflr r12 /* Make it accessible */
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mtlr r0
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lwz r11, (p_dyn - 0b)(r12)
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add r11, r11, r12 /* runtime address of .dynamic section */
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lwz r9, (p_rela - 0b)(r12)
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add r9, r9, r12 /* runtime address of .rela.dyn section */
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lwz r10, (p_st - 0b)(r12)
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add r10, r10, r12 /* runtime address of _stext section */
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lwz r13, (p_sym - 0b)(r12)
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add r13, r13, r12 /* runtime address of .dynsym section */
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/*
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* Scan the dynamic section for RELA, RELASZ entries
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*/
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li r6, 0
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li r7, 0
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li r8, 0
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1: lwz r5, 0(r11) /* ELF_Dyn.d_tag */
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cmpwi r5, 0 /* End of ELF_Dyn[] */
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beq eodyn
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cmpwi r5, DT_RELA
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bne relasz
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lwz r7, 4(r11) /* r7 = rela.link */
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b skip
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relasz:
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cmpwi r5, DT_RELASZ
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bne relaent
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lwz r8, 4(r11) /* r8 = Total Rela relocs size */
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b skip
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relaent:
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cmpwi r5, DT_RELAENT
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bne skip
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lwz r6, 4(r11) /* r6 = Size of one Rela reloc */
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skip:
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addi r11, r11, 8
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b 1b
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eodyn: /* End of Dyn Table scan */
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/* Check if we have found all the entries */
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cmpwi r7, 0
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beq done
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cmpwi r8, 0
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beq done
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cmpwi r6, 0
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beq done
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/*
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* Work out the current offset from the link time address of .rela
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* section.
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* cur_offset[r7] = rela.run[r9] - rela.link [r7]
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* _stext.link[r12] = _stext.run[r10] - cur_offset[r7]
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* final_offset[r3] = _stext.final[r3] - _stext.link[r12]
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*/
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subf r7, r7, r9 /* cur_offset */
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subf r12, r7, r10
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subf r3, r12, r3 /* final_offset */
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subf r8, r6, r8 /* relaz -= relaent */
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/*
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* Scan through the .rela table and process each entry
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* r9 - points to the current .rela table entry
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* r13 - points to the symbol table
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*/
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/*
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* Check if we have a relocation based on symbol
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* r5 will hold the value of the symbol.
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*/
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applyrela:
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lwz r4, 4(r9) /* r4 = rela.r_info */
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srwi r5, r4, 8 /* ELF32_R_SYM(r_info) */
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cmpwi r5, STN_UNDEF /* sym == STN_UNDEF ? */
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beq get_type /* value = 0 */
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/* Find the value of the symbol at index(r5) */
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slwi r5, r5, 4 /* r5 = r5 * sizeof(Elf32_Sym) */
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add r12, r13, r5 /* r12 = &__dyn_sym[Index] */
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/*
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* GNU ld has a bug, where dynamic relocs based on
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* STB_LOCAL symbols, the value should be assumed
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* to be zero. - Alan Modra
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*/
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/* XXX: Do we need to check if we are using GNU ld ? */
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lbz r5, 12(r12) /* r5 = dyn_sym[Index].st_info */
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extrwi r5, r5, 4, 24 /* r5 = ELF32_ST_BIND(r5) */
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cmpwi r5, STB_LOCAL /* st_value = 0, ld bug */
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beq get_type /* We have r5 = 0 */
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lwz r5, 4(r12) /* r5 = __dyn_sym[Index].st_value */
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get_type:
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/* Load the relocation type to r4 */
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extrwi r4, r4, 8, 24 /* r4 = ELF32_R_TYPE(r_info) = ((char*)r4)[3] */
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/* R_PPC_RELATIVE */
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cmpwi r4, R_PPC_RELATIVE
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bne hi16
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lwz r4, 0(r9) /* r_offset */
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lwz r0, 8(r9) /* r_addend */
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add r0, r0, r3 /* final addend */
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stwx r0, r4, r7 /* memory[r4+r7]) = (u32)r0 */
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b nxtrela /* continue */
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/* R_PPC_ADDR16_HI */
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hi16:
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cmpwi r4, R_PPC_ADDR16_HI
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bne ha16
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lwz r4, 0(r9) /* r_offset */
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lwz r0, 8(r9) /* r_addend */
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add r0, r0, r3
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add r0, r0, r5 /* r0 = (S+A+Offset) */
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extrwi r0, r0, 16, 0 /* r0 = (r0 >> 16) */
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b store_half
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/* R_PPC_ADDR16_HA */
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ha16:
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cmpwi r4, R_PPC_ADDR16_HA
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bne lo16
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lwz r4, 0(r9) /* r_offset */
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lwz r0, 8(r9) /* r_addend */
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add r0, r0, r3
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add r0, r0, r5 /* r0 = (S+A+Offset) */
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extrwi r5, r0, 1, 16 /* Extract bit 16 */
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extrwi r0, r0, 16, 0 /* r0 = (r0 >> 16) */
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add r0, r0, r5 /* Add it to r0 */
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b store_half
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/* R_PPC_ADDR16_LO */
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lo16:
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cmpwi r4, R_PPC_ADDR16_LO
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bne unknown_type
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lwz r4, 0(r9) /* r_offset */
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lwz r0, 8(r9) /* r_addend */
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add r0, r0, r3
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add r0, r0, r5 /* r0 = (S+A+Offset) */
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extrwi r0, r0, 16, 16 /* r0 &= 0xffff */
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/* Fall through to */
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/* Store half word */
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store_half:
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sthx r0, r4, r7 /* memory[r4+r7] = (u16)r0 */
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nxtrela:
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/*
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* We have to flush the modified instructions to the
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* main storage from the d-cache. And also, invalidate the
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* cached instructions in i-cache which has been modified.
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*
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* We delay the sync / isync operation till the end, since
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* we won't be executing the modified instructions until
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* we return from here.
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*/
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dcbst r4,r7
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sync /* Ensure the data is flushed before icbi */
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icbi r4,r7
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unknown_type:
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cmpwi r8, 0 /* relasz = 0 ? */
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ble done
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add r9, r9, r6 /* move to next entry in the .rela table */
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subf r8, r6, r8 /* relasz -= relaent */
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b applyrela
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done:
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sync /* Wait for the flush to finish */
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isync /* Discard prefetched instructions */
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blr
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p_dyn: .long __dynamic_start - 0b
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p_rela: .long __rela_dyn_start - 0b
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p_sym: .long __dynamic_symtab - 0b
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p_st: .long _stext - 0b
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