diff options
Diffstat (limited to 'arch/arm64/kernel/module.c')
| -rw-r--r-- | arch/arm64/kernel/module.c | 415 |
1 files changed, 415 insertions, 0 deletions
diff --git a/arch/arm64/kernel/module.c b/arch/arm64/kernel/module.c new file mode 100644 index 000000000..67bf4107f --- /dev/null +++ b/arch/arm64/kernel/module.c @@ -0,0 +1,415 @@ +/* + * AArch64 loadable module support. + * + * Copyright (C) 2012 ARM Limited + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see <http://www.gnu.org/licenses/>. + * + * Author: Will Deacon <will.deacon@arm.com> + */ + +#include <linux/bitops.h> +#include <linux/elf.h> +#include <linux/gfp.h> +#include <linux/kernel.h> +#include <linux/mm.h> +#include <linux/moduleloader.h> +#include <linux/vmalloc.h> +#include <asm/alternative.h> +#include <asm/insn.h> +#include <asm/sections.h> + +#define AARCH64_INSN_IMM_MOVNZ AARCH64_INSN_IMM_MAX +#define AARCH64_INSN_IMM_MOVK AARCH64_INSN_IMM_16 + +void *module_alloc(unsigned long size) +{ + return __vmalloc_node_range(size, 1, MODULES_VADDR, MODULES_END, + GFP_KERNEL, PAGE_KERNEL_EXEC, 0, + NUMA_NO_NODE, __builtin_return_address(0)); +} + +enum aarch64_reloc_op { + RELOC_OP_NONE, + RELOC_OP_ABS, + RELOC_OP_PREL, + RELOC_OP_PAGE, +}; + +static u64 do_reloc(enum aarch64_reloc_op reloc_op, void *place, u64 val) +{ + switch (reloc_op) { + case RELOC_OP_ABS: + return val; + case RELOC_OP_PREL: + return val - (u64)place; + case RELOC_OP_PAGE: + return (val & ~0xfff) - ((u64)place & ~0xfff); + case RELOC_OP_NONE: + return 0; + } + + pr_err("do_reloc: unknown relocation operation %d\n", reloc_op); + return 0; +} + +static int reloc_data(enum aarch64_reloc_op op, void *place, u64 val, int len) +{ + u64 imm_mask = (1 << len) - 1; + s64 sval = do_reloc(op, place, val); + + switch (len) { + case 16: + *(s16 *)place = sval; + break; + case 32: + *(s32 *)place = sval; + break; + case 64: + *(s64 *)place = sval; + break; + default: + pr_err("Invalid length (%d) for data relocation\n", len); + return 0; + } + + /* + * Extract the upper value bits (including the sign bit) and + * shift them to bit 0. + */ + sval = (s64)(sval & ~(imm_mask >> 1)) >> (len - 1); + + /* + * Overflow has occurred if the value is not representable in + * len bits (i.e the bottom len bits are not sign-extended and + * the top bits are not all zero). + */ + if ((u64)(sval + 1) > 2) + return -ERANGE; + + return 0; +} + +static int reloc_insn_movw(enum aarch64_reloc_op op, void *place, u64 val, + int lsb, enum aarch64_insn_imm_type imm_type) +{ + u64 imm, limit = 0; + s64 sval; + u32 insn = le32_to_cpu(*(u32 *)place); + + sval = do_reloc(op, place, val); + sval >>= lsb; + imm = sval & 0xffff; + + if (imm_type == AARCH64_INSN_IMM_MOVNZ) { + /* + * For signed MOVW relocations, we have to manipulate the + * instruction encoding depending on whether or not the + * immediate is less than zero. + */ + insn &= ~(3 << 29); + if ((s64)imm >= 0) { + /* >=0: Set the instruction to MOVZ (opcode 10b). */ + insn |= 2 << 29; + } else { + /* + * <0: Set the instruction to MOVN (opcode 00b). + * Since we've masked the opcode already, we + * don't need to do anything other than + * inverting the new immediate field. + */ + imm = ~imm; + } + imm_type = AARCH64_INSN_IMM_MOVK; + } + + /* Update the instruction with the new encoding. */ + insn = aarch64_insn_encode_immediate(imm_type, insn, imm); + *(u32 *)place = cpu_to_le32(insn); + + /* Shift out the immediate field. */ + sval >>= 16; + + /* + * For unsigned immediates, the overflow check is straightforward. + * For signed immediates, the sign bit is actually the bit past the + * most significant bit of the field. + * The AARCH64_INSN_IMM_16 immediate type is unsigned. + */ + if (imm_type != AARCH64_INSN_IMM_16) { + sval++; + limit++; + } + + /* Check the upper bits depending on the sign of the immediate. */ + if ((u64)sval > limit) + return -ERANGE; + + return 0; +} + +static int reloc_insn_imm(enum aarch64_reloc_op op, void *place, u64 val, + int lsb, int len, enum aarch64_insn_imm_type imm_type) +{ + u64 imm, imm_mask; + s64 sval; + u32 insn = le32_to_cpu(*(u32 *)place); + + /* Calculate the relocation value. */ + sval = do_reloc(op, place, val); + sval >>= lsb; + + /* Extract the value bits and shift them to bit 0. */ + imm_mask = (BIT(lsb + len) - 1) >> lsb; + imm = sval & imm_mask; + + /* Update the instruction's immediate field. */ + insn = aarch64_insn_encode_immediate(imm_type, insn, imm); + *(u32 *)place = cpu_to_le32(insn); + + /* + * Extract the upper value bits (including the sign bit) and + * shift them to bit 0. + */ + sval = (s64)(sval & ~(imm_mask >> 1)) >> (len - 1); + + /* + * Overflow has occurred if the upper bits are not all equal to + * the sign bit of the value. + */ + if ((u64)(sval + 1) >= 2) + return -ERANGE; + + return 0; +} + +int apply_relocate_add(Elf64_Shdr *sechdrs, + const char *strtab, + unsigned int symindex, + unsigned int relsec, + struct module *me) +{ + unsigned int i; + int ovf; + bool overflow_check; + Elf64_Sym *sym; + void *loc; + u64 val; + Elf64_Rela *rel = (void *)sechdrs[relsec].sh_addr; + + for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) { + /* loc corresponds to P in the AArch64 ELF document. */ + loc = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr + + rel[i].r_offset; + + /* sym is the ELF symbol we're referring to. */ + sym = (Elf64_Sym *)sechdrs[symindex].sh_addr + + ELF64_R_SYM(rel[i].r_info); + + /* val corresponds to (S + A) in the AArch64 ELF document. */ + val = sym->st_value + rel[i].r_addend; + + /* Check for overflow by default. */ + overflow_check = true; + + /* Perform the static relocation. */ + switch (ELF64_R_TYPE(rel[i].r_info)) { + /* Null relocations. */ + case R_ARM_NONE: + case R_AARCH64_NONE: + ovf = 0; + break; + + /* Data relocations. */ + case R_AARCH64_ABS64: + overflow_check = false; + ovf = reloc_data(RELOC_OP_ABS, loc, val, 64); + break; + case R_AARCH64_ABS32: + ovf = reloc_data(RELOC_OP_ABS, loc, val, 32); + break; + case R_AARCH64_ABS16: + ovf = reloc_data(RELOC_OP_ABS, loc, val, 16); + break; + case R_AARCH64_PREL64: + overflow_check = false; + ovf = reloc_data(RELOC_OP_PREL, loc, val, 64); + break; + case R_AARCH64_PREL32: + ovf = reloc_data(RELOC_OP_PREL, loc, val, 32); + break; + case R_AARCH64_PREL16: + ovf = reloc_data(RELOC_OP_PREL, loc, val, 16); + break; + + /* MOVW instruction relocations. */ + case R_AARCH64_MOVW_UABS_G0_NC: + overflow_check = false; + case R_AARCH64_MOVW_UABS_G0: + ovf = reloc_insn_movw(RELOC_OP_ABS, loc, val, 0, + AARCH64_INSN_IMM_16); + break; + case R_AARCH64_MOVW_UABS_G1_NC: + overflow_check = false; + case R_AARCH64_MOVW_UABS_G1: + ovf = reloc_insn_movw(RELOC_OP_ABS, loc, val, 16, + AARCH64_INSN_IMM_16); + break; + case R_AARCH64_MOVW_UABS_G2_NC: + overflow_check = false; + case R_AARCH64_MOVW_UABS_G2: + ovf = reloc_insn_movw(RELOC_OP_ABS, loc, val, 32, + AARCH64_INSN_IMM_16); + break; + case R_AARCH64_MOVW_UABS_G3: + /* We're using the top bits so we can't overflow. */ + overflow_check = false; + ovf = reloc_insn_movw(RELOC_OP_ABS, loc, val, 48, + AARCH64_INSN_IMM_16); + break; + case R_AARCH64_MOVW_SABS_G0: + ovf = reloc_insn_movw(RELOC_OP_ABS, loc, val, 0, + AARCH64_INSN_IMM_MOVNZ); + break; + case R_AARCH64_MOVW_SABS_G1: + ovf = reloc_insn_movw(RELOC_OP_ABS, loc, val, 16, + AARCH64_INSN_IMM_MOVNZ); + break; + case R_AARCH64_MOVW_SABS_G2: + ovf = reloc_insn_movw(RELOC_OP_ABS, loc, val, 32, + AARCH64_INSN_IMM_MOVNZ); + break; + case R_AARCH64_MOVW_PREL_G0_NC: + overflow_check = false; + ovf = reloc_insn_movw(RELOC_OP_PREL, loc, val, 0, + AARCH64_INSN_IMM_MOVK); + break; + case R_AARCH64_MOVW_PREL_G0: + ovf = reloc_insn_movw(RELOC_OP_PREL, loc, val, 0, + AARCH64_INSN_IMM_MOVNZ); + break; + case R_AARCH64_MOVW_PREL_G1_NC: + overflow_check = false; + ovf = reloc_insn_movw(RELOC_OP_PREL, loc, val, 16, + AARCH64_INSN_IMM_MOVK); + break; + case R_AARCH64_MOVW_PREL_G1: + ovf = reloc_insn_movw(RELOC_OP_PREL, loc, val, 16, + AARCH64_INSN_IMM_MOVNZ); + break; + case R_AARCH64_MOVW_PREL_G2_NC: + overflow_check = false; + ovf = reloc_insn_movw(RELOC_OP_PREL, loc, val, 32, + AARCH64_INSN_IMM_MOVK); + break; + case R_AARCH64_MOVW_PREL_G2: + ovf = reloc_insn_movw(RELOC_OP_PREL, loc, val, 32, + AARCH64_INSN_IMM_MOVNZ); + break; + case R_AARCH64_MOVW_PREL_G3: + /* We're using the top bits so we can't overflow. */ + overflow_check = false; + ovf = reloc_insn_movw(RELOC_OP_PREL, loc, val, 48, + AARCH64_INSN_IMM_MOVNZ); + break; + + /* Immediate instruction relocations. */ + case R_AARCH64_LD_PREL_LO19: + ovf = reloc_insn_imm(RELOC_OP_PREL, loc, val, 2, 19, + AARCH64_INSN_IMM_19); + break; + case R_AARCH64_ADR_PREL_LO21: + ovf = reloc_insn_imm(RELOC_OP_PREL, loc, val, 0, 21, + AARCH64_INSN_IMM_ADR); + break; + case R_AARCH64_ADR_PREL_PG_HI21_NC: + overflow_check = false; + case R_AARCH64_ADR_PREL_PG_HI21: + ovf = reloc_insn_imm(RELOC_OP_PAGE, loc, val, 12, 21, + AARCH64_INSN_IMM_ADR); + break; + case R_AARCH64_ADD_ABS_LO12_NC: + case R_AARCH64_LDST8_ABS_LO12_NC: + overflow_check = false; + ovf = reloc_insn_imm(RELOC_OP_ABS, loc, val, 0, 12, + AARCH64_INSN_IMM_12); + break; + case R_AARCH64_LDST16_ABS_LO12_NC: + overflow_check = false; + ovf = reloc_insn_imm(RELOC_OP_ABS, loc, val, 1, 11, + AARCH64_INSN_IMM_12); + break; + case R_AARCH64_LDST32_ABS_LO12_NC: + overflow_check = false; + ovf = reloc_insn_imm(RELOC_OP_ABS, loc, val, 2, 10, + AARCH64_INSN_IMM_12); + break; + case R_AARCH64_LDST64_ABS_LO12_NC: + overflow_check = false; + ovf = reloc_insn_imm(RELOC_OP_ABS, loc, val, 3, 9, + AARCH64_INSN_IMM_12); + break; + case R_AARCH64_LDST128_ABS_LO12_NC: + overflow_check = false; + ovf = reloc_insn_imm(RELOC_OP_ABS, loc, val, 4, 8, + AARCH64_INSN_IMM_12); + break; + case R_AARCH64_TSTBR14: + ovf = reloc_insn_imm(RELOC_OP_PREL, loc, val, 2, 14, + AARCH64_INSN_IMM_14); + break; + case R_AARCH64_CONDBR19: + ovf = reloc_insn_imm(RELOC_OP_PREL, loc, val, 2, 19, + AARCH64_INSN_IMM_19); + break; + case R_AARCH64_JUMP26: + case R_AARCH64_CALL26: + ovf = reloc_insn_imm(RELOC_OP_PREL, loc, val, 2, 26, + AARCH64_INSN_IMM_26); + break; + + default: + pr_err("module %s: unsupported RELA relocation: %llu\n", + me->name, ELF64_R_TYPE(rel[i].r_info)); + return -ENOEXEC; + } + + if (overflow_check && ovf == -ERANGE) + goto overflow; + + } + + return 0; + +overflow: + pr_err("module %s: overflow in relocation type %d val %Lx\n", + me->name, (int)ELF64_R_TYPE(rel[i].r_info), val); + return -ENOEXEC; +} + +int module_finalize(const Elf_Ehdr *hdr, + const Elf_Shdr *sechdrs, + struct module *me) +{ + const Elf_Shdr *s, *se; + const char *secstrs = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset; + + for (s = sechdrs, se = sechdrs + hdr->e_shnum; s < se; s++) { + if (strcmp(".altinstructions", secstrs + s->sh_name) == 0) { + apply_alternatives((void *)s->sh_addr, s->sh_size); + return 0; + } + } + + return 0; +} |