reloc_32.S (5349B)
1/* SPDX-License-Identifier: GPL-2.0-or-later */ 2/* 3 * Code to process dynamic relocations for PPC32. 4 * 5 * Copyrights (C) IBM Corporation, 2011. 6 * Author: Suzuki Poulose <suzuki@in.ibm.com> 7 * 8 * - Based on ppc64 code - reloc_64.S 9 */ 10 11#include <asm/ppc_asm.h> 12 13/* Dynamic section table entry tags */ 14DT_RELA = 7 /* Tag for Elf32_Rela section */ 15DT_RELASZ = 8 /* Size of the Rela relocs */ 16DT_RELAENT = 9 /* Size of one Rela reloc entry */ 17 18STN_UNDEF = 0 /* Undefined symbol index */ 19STB_LOCAL = 0 /* Local binding for the symbol */ 20 21R_PPC_ADDR16_LO = 4 /* Lower half of (S+A) */ 22R_PPC_ADDR16_HI = 5 /* Upper half of (S+A) */ 23R_PPC_ADDR16_HA = 6 /* High Adjusted (S+A) */ 24R_PPC_RELATIVE = 22 25 26/* 27 * r3 = desired final address 28 */ 29 30_GLOBAL(relocate) 31 32 mflr r0 /* Save our LR */ 33 bcl 20,31,$+4 /* Find our current runtime address */ 340: mflr r12 /* Make it accessible */ 35 mtlr r0 36 37 lwz r11, (p_dyn - 0b)(r12) 38 add r11, r11, r12 /* runtime address of .dynamic section */ 39 lwz r9, (p_rela - 0b)(r12) 40 add r9, r9, r12 /* runtime address of .rela.dyn section */ 41 lwz r10, (p_st - 0b)(r12) 42 add r10, r10, r12 /* runtime address of _stext section */ 43 lwz r13, (p_sym - 0b)(r12) 44 add r13, r13, r12 /* runtime address of .dynsym section */ 45 46 /* 47 * Scan the dynamic section for RELA, RELASZ entries 48 */ 49 li r6, 0 50 li r7, 0 51 li r8, 0 521: lwz r5, 0(r11) /* ELF_Dyn.d_tag */ 53 cmpwi r5, 0 /* End of ELF_Dyn[] */ 54 beq eodyn 55 cmpwi r5, DT_RELA 56 bne relasz 57 lwz r7, 4(r11) /* r7 = rela.link */ 58 b skip 59relasz: 60 cmpwi r5, DT_RELASZ 61 bne relaent 62 lwz r8, 4(r11) /* r8 = Total Rela relocs size */ 63 b skip 64relaent: 65 cmpwi r5, DT_RELAENT 66 bne skip 67 lwz r6, 4(r11) /* r6 = Size of one Rela reloc */ 68skip: 69 addi r11, r11, 8 70 b 1b 71eodyn: /* End of Dyn Table scan */ 72 73 /* Check if we have found all the entries */ 74 cmpwi r7, 0 75 beq done 76 cmpwi r8, 0 77 beq done 78 cmpwi r6, 0 79 beq done 80 81 82 /* 83 * Work out the current offset from the link time address of .rela 84 * section. 85 * cur_offset[r7] = rela.run[r9] - rela.link [r7] 86 * _stext.link[r12] = _stext.run[r10] - cur_offset[r7] 87 * final_offset[r3] = _stext.final[r3] - _stext.link[r12] 88 */ 89 subf r7, r7, r9 /* cur_offset */ 90 subf r12, r7, r10 91 subf r3, r12, r3 /* final_offset */ 92 93 subf r8, r6, r8 /* relaz -= relaent */ 94 /* 95 * Scan through the .rela table and process each entry 96 * r9 - points to the current .rela table entry 97 * r13 - points to the symbol table 98 */ 99 100 /* 101 * Check if we have a relocation based on symbol 102 * r5 will hold the value of the symbol. 103 */ 104applyrela: 105 lwz r4, 4(r9) /* r4 = rela.r_info */ 106 srwi r5, r4, 8 /* ELF32_R_SYM(r_info) */ 107 cmpwi r5, STN_UNDEF /* sym == STN_UNDEF ? */ 108 beq get_type /* value = 0 */ 109 /* Find the value of the symbol at index(r5) */ 110 slwi r5, r5, 4 /* r5 = r5 * sizeof(Elf32_Sym) */ 111 add r12, r13, r5 /* r12 = &__dyn_sym[Index] */ 112 113 /* 114 * GNU ld has a bug, where dynamic relocs based on 115 * STB_LOCAL symbols, the value should be assumed 116 * to be zero. - Alan Modra 117 */ 118 /* XXX: Do we need to check if we are using GNU ld ? */ 119 lbz r5, 12(r12) /* r5 = dyn_sym[Index].st_info */ 120 extrwi r5, r5, 4, 24 /* r5 = ELF32_ST_BIND(r5) */ 121 cmpwi r5, STB_LOCAL /* st_value = 0, ld bug */ 122 beq get_type /* We have r5 = 0 */ 123 lwz r5, 4(r12) /* r5 = __dyn_sym[Index].st_value */ 124 125get_type: 126 /* Load the relocation type to r4 */ 127 extrwi r4, r4, 8, 24 /* r4 = ELF32_R_TYPE(r_info) = ((char*)r4)[3] */ 128 129 /* R_PPC_RELATIVE */ 130 cmpwi r4, R_PPC_RELATIVE 131 bne hi16 132 lwz r4, 0(r9) /* r_offset */ 133 lwz r0, 8(r9) /* r_addend */ 134 add r0, r0, r3 /* final addend */ 135 stwx r0, r4, r7 /* memory[r4+r7]) = (u32)r0 */ 136 b nxtrela /* continue */ 137 138 /* R_PPC_ADDR16_HI */ 139hi16: 140 cmpwi r4, R_PPC_ADDR16_HI 141 bne ha16 142 lwz r4, 0(r9) /* r_offset */ 143 lwz r0, 8(r9) /* r_addend */ 144 add r0, r0, r3 145 add r0, r0, r5 /* r0 = (S+A+Offset) */ 146 extrwi r0, r0, 16, 0 /* r0 = (r0 >> 16) */ 147 b store_half 148 149 /* R_PPC_ADDR16_HA */ 150ha16: 151 cmpwi r4, R_PPC_ADDR16_HA 152 bne lo16 153 lwz r4, 0(r9) /* r_offset */ 154 lwz r0, 8(r9) /* r_addend */ 155 add r0, r0, r3 156 add r0, r0, r5 /* r0 = (S+A+Offset) */ 157 extrwi r5, r0, 1, 16 /* Extract bit 16 */ 158 extrwi r0, r0, 16, 0 /* r0 = (r0 >> 16) */ 159 add r0, r0, r5 /* Add it to r0 */ 160 b store_half 161 162 /* R_PPC_ADDR16_LO */ 163lo16: 164 cmpwi r4, R_PPC_ADDR16_LO 165 bne unknown_type 166 lwz r4, 0(r9) /* r_offset */ 167 lwz r0, 8(r9) /* r_addend */ 168 add r0, r0, r3 169 add r0, r0, r5 /* r0 = (S+A+Offset) */ 170 extrwi r0, r0, 16, 16 /* r0 &= 0xffff */ 171 /* Fall through to */ 172 173 /* Store half word */ 174store_half: 175 sthx r0, r4, r7 /* memory[r4+r7] = (u16)r0 */ 176 177nxtrela: 178 /* 179 * We have to flush the modified instructions to the 180 * main storage from the d-cache. And also, invalidate the 181 * cached instructions in i-cache which has been modified. 182 * 183 * We delay the sync / isync operation till the end, since 184 * we won't be executing the modified instructions until 185 * we return from here. 186 */ 187 dcbst r4,r7 188 sync /* Ensure the data is flushed before icbi */ 189 icbi r4,r7 190unknown_type: 191 cmpwi r8, 0 /* relasz = 0 ? */ 192 ble done 193 add r9, r9, r6 /* move to next entry in the .rela table */ 194 subf r8, r6, r8 /* relasz -= relaent */ 195 b applyrela 196 197done: 198 sync /* Wait for the flush to finish */ 199 isync /* Discard prefetched instructions */ 200 blr 201 202p_dyn: .long __dynamic_start - 0b 203p_rela: .long __rela_dyn_start - 0b 204p_sym: .long __dynamic_symtab - 0b 205p_st: .long _stext - 0b