| /* |
| * 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 nxtrela |
| 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 |
| 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 |