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-rw-r--r--tools/objtool/arch/x86/decode.c496
1 files changed, 496 insertions, 0 deletions
diff --git a/tools/objtool/arch/x86/decode.c b/tools/objtool/arch/x86/decode.c
new file mode 100644
index 000000000..540a209b7
--- /dev/null
+++ b/tools/objtool/arch/x86/decode.c
@@ -0,0 +1,496 @@
+/*
+ * 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 <asm/insn.h>
+#include "lib/inat.c"
+#include "lib/insn.c"
+
+#include "../../elf.h"
+#include "../../arch.h"
+#include "../../warn.h"
+
+static unsigned char op_to_cfi_reg[][2] = {
+ {CFI_AX, CFI_R8},
+ {CFI_CX, CFI_R9},
+ {CFI_DX, CFI_R10},
+ {CFI_BX, CFI_R11},
+ {CFI_SP, CFI_R12},
+ {CFI_BP, CFI_R13},
+ {CFI_SI, CFI_R14},
+ {CFI_DI, CFI_R15},
+};
+
+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;
+ }
+}
+
+bool arch_callee_saved_reg(unsigned char reg)
+{
+ switch (reg) {
+ case CFI_BP:
+ case CFI_BX:
+ case CFI_R12:
+ case CFI_R13:
+ case CFI_R14:
+ case CFI_R15:
+ return true;
+
+ case CFI_AX:
+ case CFI_CX:
+ case CFI_DX:
+ case CFI_SI:
+ case CFI_DI:
+ case CFI_SP:
+ case CFI_R8:
+ case CFI_R9:
+ case CFI_R10:
+ case CFI_R11:
+ case CFI_RA:
+ default:
+ return false;
+ }
+}
+
+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 stack_op *op)
+{
+ struct insn insn;
+ int x86_64, sign;
+ unsigned char op1, op2, rex = 0, rex_b = 0, rex_r = 0, rex_w = 0,
+ rex_x = 0, modrm = 0, modrm_mod = 0, modrm_rm = 0,
+ modrm_reg = 0, sib = 0;
+
+ x86_64 = is_x86_64(elf);
+ if (x86_64 == -1)
+ return -1;
+
+ insn_init(&insn, sec->data->d_buf + offset, maxlen, x86_64);
+ insn_get_length(&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];
+
+ if (insn.rex_prefix.nbytes) {
+ rex = insn.rex_prefix.bytes[0];
+ rex_w = X86_REX_W(rex) >> 3;
+ rex_r = X86_REX_R(rex) >> 2;
+ rex_x = X86_REX_X(rex) >> 1;
+ rex_b = X86_REX_B(rex);
+ }
+
+ if (insn.modrm.nbytes) {
+ modrm = insn.modrm.bytes[0];
+ modrm_mod = X86_MODRM_MOD(modrm);
+ modrm_reg = X86_MODRM_REG(modrm);
+ modrm_rm = X86_MODRM_RM(modrm);
+ }
+
+ if (insn.sib.nbytes)
+ sib = insn.sib.bytes[0];
+
+ switch (op1) {
+
+ case 0x1:
+ case 0x29:
+ if (rex_w && !rex_b && modrm_mod == 3 && modrm_rm == 4) {
+
+ /* add/sub reg, %rsp */
+ *type = INSN_STACK;
+ op->src.type = OP_SRC_ADD;
+ op->src.reg = op_to_cfi_reg[modrm_reg][rex_r];
+ op->dest.type = OP_DEST_REG;
+ op->dest.reg = CFI_SP;
+ }
+ break;
+
+ case 0x50 ... 0x57:
+
+ /* push reg */
+ *type = INSN_STACK;
+ op->src.type = OP_SRC_REG;
+ op->src.reg = op_to_cfi_reg[op1 & 0x7][rex_b];
+ op->dest.type = OP_DEST_PUSH;
+
+ break;
+
+ case 0x58 ... 0x5f:
+
+ /* pop reg */
+ *type = INSN_STACK;
+ op->src.type = OP_SRC_POP;
+ op->dest.type = OP_DEST_REG;
+ op->dest.reg = op_to_cfi_reg[op1 & 0x7][rex_b];
+
+ break;
+
+ case 0x68:
+ case 0x6a:
+ /* push immediate */
+ *type = INSN_STACK;
+ op->src.type = OP_SRC_CONST;
+ op->dest.type = OP_DEST_PUSH;
+ break;
+
+ case 0x70 ... 0x7f:
+ *type = INSN_JUMP_CONDITIONAL;
+ break;
+
+ case 0x81:
+ case 0x83:
+ if (rex != 0x48)
+ break;
+
+ if (modrm == 0xe4) {
+ /* and imm, %rsp */
+ *type = INSN_STACK;
+ op->src.type = OP_SRC_AND;
+ op->src.reg = CFI_SP;
+ op->src.offset = insn.immediate.value;
+ op->dest.type = OP_DEST_REG;
+ op->dest.reg = CFI_SP;
+ break;
+ }
+
+ if (modrm == 0xc4)
+ sign = 1;
+ else if (modrm == 0xec)
+ sign = -1;
+ else
+ break;
+
+ /* add/sub imm, %rsp */
+ *type = INSN_STACK;
+ op->src.type = OP_SRC_ADD;
+ op->src.reg = CFI_SP;
+ op->src.offset = insn.immediate.value * sign;
+ op->dest.type = OP_DEST_REG;
+ op->dest.reg = CFI_SP;
+ break;
+
+ case 0x89:
+ if (rex_w && !rex_r && modrm_mod == 3 && modrm_reg == 4) {
+
+ /* mov %rsp, reg */
+ *type = INSN_STACK;
+ op->src.type = OP_SRC_REG;
+ op->src.reg = CFI_SP;
+ op->dest.type = OP_DEST_REG;
+ op->dest.reg = op_to_cfi_reg[modrm_rm][rex_b];
+ break;
+ }
+
+ if (rex_w && !rex_b && modrm_mod == 3 && modrm_rm == 4) {
+
+ /* mov reg, %rsp */
+ *type = INSN_STACK;
+ op->src.type = OP_SRC_REG;
+ op->src.reg = op_to_cfi_reg[modrm_reg][rex_r];
+ op->dest.type = OP_DEST_REG;
+ op->dest.reg = CFI_SP;
+ break;
+ }
+
+ /* fallthrough */
+ case 0x88:
+ if (!rex_b &&
+ (modrm_mod == 1 || modrm_mod == 2) && modrm_rm == 5) {
+
+ /* mov reg, disp(%rbp) */
+ *type = INSN_STACK;
+ op->src.type = OP_SRC_REG;
+ op->src.reg = op_to_cfi_reg[modrm_reg][rex_r];
+ op->dest.type = OP_DEST_REG_INDIRECT;
+ op->dest.reg = CFI_BP;
+ op->dest.offset = insn.displacement.value;
+
+ } else if (rex_w && !rex_b && modrm_rm == 4 && sib == 0x24) {
+
+ /* mov reg, disp(%rsp) */
+ *type = INSN_STACK;
+ op->src.type = OP_SRC_REG;
+ op->src.reg = op_to_cfi_reg[modrm_reg][rex_r];
+ op->dest.type = OP_DEST_REG_INDIRECT;
+ op->dest.reg = CFI_SP;
+ op->dest.offset = insn.displacement.value;
+ }
+
+ break;
+
+ case 0x8b:
+ if (rex_w && !rex_b && modrm_mod == 1 && modrm_rm == 5) {
+
+ /* mov disp(%rbp), reg */
+ *type = INSN_STACK;
+ op->src.type = OP_SRC_REG_INDIRECT;
+ op->src.reg = CFI_BP;
+ op->src.offset = insn.displacement.value;
+ op->dest.type = OP_DEST_REG;
+ op->dest.reg = op_to_cfi_reg[modrm_reg][rex_r];
+
+ } else if (rex_w && !rex_b && sib == 0x24 &&
+ modrm_mod != 3 && modrm_rm == 4) {
+
+ /* mov disp(%rsp), reg */
+ *type = INSN_STACK;
+ op->src.type = OP_SRC_REG_INDIRECT;
+ op->src.reg = CFI_SP;
+ op->src.offset = insn.displacement.value;
+ op->dest.type = OP_DEST_REG;
+ op->dest.reg = op_to_cfi_reg[modrm_reg][rex_r];
+ }
+
+ break;
+
+ case 0x8d:
+ if (sib == 0x24 && rex_w && !rex_b && !rex_x) {
+
+ *type = INSN_STACK;
+ if (!insn.displacement.value) {
+ /* lea (%rsp), reg */
+ op->src.type = OP_SRC_REG;
+ } else {
+ /* lea disp(%rsp), reg */
+ op->src.type = OP_SRC_ADD;
+ op->src.offset = insn.displacement.value;
+ }
+ op->src.reg = CFI_SP;
+ op->dest.type = OP_DEST_REG;
+ op->dest.reg = op_to_cfi_reg[modrm_reg][rex_r];
+
+ } else if (rex == 0x48 && modrm == 0x65) {
+
+ /* lea disp(%rbp), %rsp */
+ *type = INSN_STACK;
+ op->src.type = OP_SRC_ADD;
+ op->src.reg = CFI_BP;
+ op->src.offset = insn.displacement.value;
+ op->dest.type = OP_DEST_REG;
+ op->dest.reg = CFI_SP;
+
+ } else if (rex == 0x49 && modrm == 0x62 &&
+ insn.displacement.value == -8) {
+
+ /*
+ * lea -0x8(%r10), %rsp
+ *
+ * Restoring rsp back to its original value after a
+ * stack realignment.
+ */
+ *type = INSN_STACK;
+ op->src.type = OP_SRC_ADD;
+ op->src.reg = CFI_R10;
+ op->src.offset = -8;
+ op->dest.type = OP_DEST_REG;
+ op->dest.reg = CFI_SP;
+
+ } else if (rex == 0x49 && modrm == 0x65 &&
+ insn.displacement.value == -16) {
+
+ /*
+ * lea -0x10(%r13), %rsp
+ *
+ * Restoring rsp back to its original value after a
+ * stack realignment.
+ */
+ *type = INSN_STACK;
+ op->src.type = OP_SRC_ADD;
+ op->src.reg = CFI_R13;
+ op->src.offset = -16;
+ op->dest.type = OP_DEST_REG;
+ op->dest.reg = CFI_SP;
+ }
+
+ break;
+
+ case 0x8f:
+ /* pop to mem */
+ *type = INSN_STACK;
+ op->src.type = OP_SRC_POP;
+ op->dest.type = OP_DEST_MEM;
+ break;
+
+ case 0x90:
+ *type = INSN_NOP;
+ break;
+
+ case 0x9c:
+ /* pushf */
+ *type = INSN_STACK;
+ op->src.type = OP_SRC_CONST;
+ op->dest.type = OP_DEST_PUSH;
+ break;
+
+ case 0x9d:
+ /* popf */
+ *type = INSN_STACK;
+ op->src.type = OP_SRC_POP;
+ op->dest.type = OP_DEST_MEM;
+ 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 == 0xa0 || op2 == 0xa8) {
+
+ /* push fs/gs */
+ *type = INSN_STACK;
+ op->src.type = OP_SRC_CONST;
+ op->dest.type = OP_DEST_PUSH;
+
+ } else if (op2 == 0xa1 || op2 == 0xa9) {
+
+ /* pop fs/gs */
+ *type = INSN_STACK;
+ op->src.type = OP_SRC_POP;
+ op->dest.type = OP_DEST_MEM;
+ }
+
+ break;
+
+ case 0xc9:
+ /*
+ * leave
+ *
+ * equivalent to:
+ * mov bp, sp
+ * pop bp
+ */
+ *type = INSN_STACK;
+ op->dest.type = OP_DEST_LEAVE;
+
+ 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 0xca: /* retf */
+ case 0xcb: /* retf */
+ case 0xcf: /* iret */
+ *type = INSN_CONTEXT_SWITCH;
+ break;
+
+ case 0xe8:
+ *type = INSN_CALL;
+ break;
+
+ case 0xff:
+ if (modrm_reg == 2 || modrm_reg == 3)
+
+ *type = INSN_CALL_DYNAMIC;
+
+ else if (modrm_reg == 4)
+
+ *type = INSN_JUMP_DYNAMIC;
+
+ else if (modrm_reg == 5)
+
+ /* jmpf */
+ *type = INSN_CONTEXT_SWITCH;
+
+ else if (modrm_reg == 6) {
+
+ /* push from mem */
+ *type = INSN_STACK;
+ op->src.type = OP_SRC_CONST;
+ op->dest.type = OP_DEST_PUSH;
+ }
+
+ break;
+
+ default:
+ break;
+ }
+
+ *immediate = insn.immediate.nbytes ? insn.immediate.value : 0;
+
+ return 0;
+}
+
+void arch_initial_func_cfi_state(struct cfi_state *state)
+{
+ int i;
+
+ for (i = 0; i < CFI_NUM_REGS; i++) {
+ state->regs[i].base = CFI_UNDEFINED;
+ state->regs[i].offset = 0;
+ }
+
+ /* initial CFA (call frame address) */
+ state->cfa.base = CFI_SP;
+ state->cfa.offset = 8;
+
+ /* initial RA (return address) */
+ state->regs[16].base = CFI_CFA;
+ state->regs[16].offset = -8;
+}
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