diff options
Diffstat (limited to 'arch/powerpc/kernel/reloc_32.S')
| -rw-r--r-- | arch/powerpc/kernel/reloc_32.S | 205 |
1 files changed, 205 insertions, 0 deletions
diff --git a/arch/powerpc/kernel/reloc_32.S b/arch/powerpc/kernel/reloc_32.S new file mode 100644 index 000000000..10e96f3e2 --- /dev/null +++ b/arch/powerpc/kernel/reloc_32.S @@ -0,0 +1,205 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ +/* + * 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 + */ + +#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 |