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205 lines
5.2 KiB
205 lines
5.2 KiB
/* SPDX-License-Identifier: GPL-2.0-or-later */ |
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/* |
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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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#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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