diff options
Diffstat (limited to 'tools/objtool/arch/x86/decode.c')
| -rw-r--r-- | tools/objtool/arch/x86/decode.c | 172 |
1 files changed, 172 insertions, 0 deletions
diff --git a/tools/objtool/arch/x86/decode.c b/tools/objtool/arch/x86/decode.c new file mode 100644 index 000000000000..c0c0b265e88e --- /dev/null +++ b/tools/objtool/arch/x86/decode.c @@ -0,0 +1,172 @@ +/* + * Copyright (C) 2015 Josh Poimboeuf <jpoimboe@redhat.com> + * + * 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. + * + * 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/>. + */ + +#include <stdio.h> +#include <stdlib.h> + +#define unlikely(cond) (cond) +#include "insn/insn.h" +#include "insn/inat.c" +#include "insn/insn.c" + +#include "../../elf.h" +#include "../../arch.h" +#include "../../warn.h" + +static int is_x86_64(struct elf *elf) +{ + switch (elf->ehdr.e_machine) { + case EM_X86_64: + return 1; + case EM_386: + return 0; + default: + WARN("unexpected ELF machine type %d", elf->ehdr.e_machine); + return -1; + } +} + +int arch_decode_instruction(struct elf *elf, struct section *sec, + unsigned long offset, unsigned int maxlen, + unsigned int *len, unsigned char *type, + unsigned long *immediate) +{ + struct insn insn; + int x86_64; + unsigned char op1, op2, ext; + + x86_64 = is_x86_64(elf); + if (x86_64 == -1) + return -1; + + insn_init(&insn, (void *)(sec->data + offset), maxlen, x86_64); + insn_get_length(&insn); + insn_get_opcode(&insn); + insn_get_modrm(&insn); + insn_get_immediate(&insn); + + if (!insn_complete(&insn)) { + WARN_FUNC("can't decode instruction", sec, offset); + return -1; + } + + *len = insn.length; + *type = INSN_OTHER; + + if (insn.vex_prefix.nbytes) + return 0; + + op1 = insn.opcode.bytes[0]; + op2 = insn.opcode.bytes[1]; + + switch (op1) { + case 0x55: + if (!insn.rex_prefix.nbytes) + /* push rbp */ + *type = INSN_FP_SAVE; + break; + + case 0x5d: + if (!insn.rex_prefix.nbytes) + /* pop rbp */ + *type = INSN_FP_RESTORE; + break; + + case 0x70 ... 0x7f: + *type = INSN_JUMP_CONDITIONAL; + break; + + case 0x89: + if (insn.rex_prefix.nbytes == 1 && + insn.rex_prefix.bytes[0] == 0x48 && + insn.modrm.nbytes && insn.modrm.bytes[0] == 0xe5) + /* mov rsp, rbp */ + *type = INSN_FP_SETUP; + break; + + case 0x90: + *type = INSN_NOP; + break; + + case 0x0f: + if (op2 >= 0x80 && op2 <= 0x8f) + *type = INSN_JUMP_CONDITIONAL; + else if (op2 == 0x05 || op2 == 0x07 || op2 == 0x34 || + op2 == 0x35) + /* sysenter, sysret */ + *type = INSN_CONTEXT_SWITCH; + else if (op2 == 0x0b || op2 == 0xb9) + /* ud2 */ + *type = INSN_BUG; + else if (op2 == 0x0d || op2 == 0x1f) + /* nopl/nopw */ + *type = INSN_NOP; + else if (op2 == 0x01 && insn.modrm.nbytes && + (insn.modrm.bytes[0] == 0xc2 || + insn.modrm.bytes[0] == 0xd8)) + /* vmlaunch, vmrun */ + *type = INSN_CONTEXT_SWITCH; + + break; + + case 0xc9: /* leave */ + *type = INSN_FP_RESTORE; + break; + + case 0xe3: /* jecxz/jrcxz */ + *type = INSN_JUMP_CONDITIONAL; + break; + + case 0xe9: + case 0xeb: + *type = INSN_JUMP_UNCONDITIONAL; + break; + + case 0xc2: + case 0xc3: + *type = INSN_RETURN; + break; + + case 0xc5: /* iret */ + case 0xca: /* retf */ + case 0xcb: /* retf */ + *type = INSN_CONTEXT_SWITCH; + break; + + case 0xe8: + *type = INSN_CALL; + break; + + case 0xff: + ext = X86_MODRM_REG(insn.modrm.bytes[0]); + if (ext == 2 || ext == 3) + *type = INSN_CALL_DYNAMIC; + else if (ext == 4) + *type = INSN_JUMP_DYNAMIC; + else if (ext == 5) /*jmpf */ + *type = INSN_CONTEXT_SWITCH; + + break; + + default: + break; + } + + *immediate = insn.immediate.nbytes ? insn.immediate.value : 0; + + return 0; +} |