756 строки
18 KiB
C
756 строки
18 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* x86 instruction analysis
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*
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* Copyright (C) IBM Corporation, 2002, 2004, 2009
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*/
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#include <linux/kernel.h>
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#ifdef __KERNEL__
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#include <linux/string.h>
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#else
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#include <string.h>
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#endif
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#include <asm/inat.h> /*__ignore_sync_check__ */
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#include <asm/insn.h> /* __ignore_sync_check__ */
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#include <asm/unaligned.h> /* __ignore_sync_check__ */
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#include <linux/errno.h>
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#include <linux/kconfig.h>
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#include <asm/emulate_prefix.h> /* __ignore_sync_check__ */
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#define leXX_to_cpu(t, r) \
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({ \
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__typeof__(t) v; \
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switch (sizeof(t)) { \
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case 4: v = le32_to_cpu(r); break; \
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case 2: v = le16_to_cpu(r); break; \
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case 1: v = r; break; \
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default: \
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BUILD_BUG(); break; \
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} \
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v; \
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})
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/* Verify next sizeof(t) bytes can be on the same instruction */
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#define validate_next(t, insn, n) \
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((insn)->next_byte + sizeof(t) + n <= (insn)->end_kaddr)
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#define __get_next(t, insn) \
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({ t r = get_unaligned((t *)(insn)->next_byte); (insn)->next_byte += sizeof(t); leXX_to_cpu(t, r); })
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#define __peek_nbyte_next(t, insn, n) \
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({ t r = get_unaligned((t *)(insn)->next_byte + n); leXX_to_cpu(t, r); })
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#define get_next(t, insn) \
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({ if (unlikely(!validate_next(t, insn, 0))) goto err_out; __get_next(t, insn); })
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#define peek_nbyte_next(t, insn, n) \
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({ if (unlikely(!validate_next(t, insn, n))) goto err_out; __peek_nbyte_next(t, insn, n); })
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#define peek_next(t, insn) peek_nbyte_next(t, insn, 0)
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/**
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* insn_init() - initialize struct insn
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* @insn: &struct insn to be initialized
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* @kaddr: address (in kernel memory) of instruction (or copy thereof)
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* @buf_len: length of the insn buffer at @kaddr
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* @x86_64: !0 for 64-bit kernel or 64-bit app
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*/
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void insn_init(struct insn *insn, const void *kaddr, int buf_len, int x86_64)
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{
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/*
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* Instructions longer than MAX_INSN_SIZE (15 bytes) are invalid
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* even if the input buffer is long enough to hold them.
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*/
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if (buf_len > MAX_INSN_SIZE)
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buf_len = MAX_INSN_SIZE;
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memset(insn, 0, sizeof(*insn));
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insn->kaddr = kaddr;
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insn->end_kaddr = kaddr + buf_len;
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insn->next_byte = kaddr;
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insn->x86_64 = x86_64 ? 1 : 0;
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insn->opnd_bytes = 4;
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if (x86_64)
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insn->addr_bytes = 8;
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else
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insn->addr_bytes = 4;
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}
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static const insn_byte_t xen_prefix[] = { __XEN_EMULATE_PREFIX };
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static const insn_byte_t kvm_prefix[] = { __KVM_EMULATE_PREFIX };
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static int __insn_get_emulate_prefix(struct insn *insn,
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const insn_byte_t *prefix, size_t len)
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{
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size_t i;
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for (i = 0; i < len; i++) {
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if (peek_nbyte_next(insn_byte_t, insn, i) != prefix[i])
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goto err_out;
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}
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insn->emulate_prefix_size = len;
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insn->next_byte += len;
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return 1;
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err_out:
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return 0;
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}
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static void insn_get_emulate_prefix(struct insn *insn)
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{
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if (__insn_get_emulate_prefix(insn, xen_prefix, sizeof(xen_prefix)))
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return;
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__insn_get_emulate_prefix(insn, kvm_prefix, sizeof(kvm_prefix));
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}
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/**
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* insn_get_prefixes - scan x86 instruction prefix bytes
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* @insn: &struct insn containing instruction
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*
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* Populates the @insn->prefixes bitmap, and updates @insn->next_byte
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* to point to the (first) opcode. No effect if @insn->prefixes.got
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* is already set.
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*
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* * Returns:
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* 0: on success
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* < 0: on error
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*/
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int insn_get_prefixes(struct insn *insn)
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{
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struct insn_field *prefixes = &insn->prefixes;
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insn_attr_t attr;
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insn_byte_t b, lb;
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int i, nb;
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if (prefixes->got)
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return 0;
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insn_get_emulate_prefix(insn);
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nb = 0;
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lb = 0;
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b = peek_next(insn_byte_t, insn);
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attr = inat_get_opcode_attribute(b);
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while (inat_is_legacy_prefix(attr)) {
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/* Skip if same prefix */
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for (i = 0; i < nb; i++)
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if (prefixes->bytes[i] == b)
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goto found;
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if (nb == 4)
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/* Invalid instruction */
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break;
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prefixes->bytes[nb++] = b;
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if (inat_is_address_size_prefix(attr)) {
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/* address size switches 2/4 or 4/8 */
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if (insn->x86_64)
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insn->addr_bytes ^= 12;
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else
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insn->addr_bytes ^= 6;
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} else if (inat_is_operand_size_prefix(attr)) {
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/* oprand size switches 2/4 */
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insn->opnd_bytes ^= 6;
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}
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found:
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prefixes->nbytes++;
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insn->next_byte++;
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lb = b;
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b = peek_next(insn_byte_t, insn);
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attr = inat_get_opcode_attribute(b);
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}
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/* Set the last prefix */
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if (lb && lb != insn->prefixes.bytes[3]) {
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if (unlikely(insn->prefixes.bytes[3])) {
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/* Swap the last prefix */
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b = insn->prefixes.bytes[3];
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for (i = 0; i < nb; i++)
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if (prefixes->bytes[i] == lb)
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insn_set_byte(prefixes, i, b);
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}
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insn_set_byte(&insn->prefixes, 3, lb);
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}
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/* Decode REX prefix */
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if (insn->x86_64) {
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b = peek_next(insn_byte_t, insn);
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attr = inat_get_opcode_attribute(b);
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if (inat_is_rex_prefix(attr)) {
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insn_field_set(&insn->rex_prefix, b, 1);
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insn->next_byte++;
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if (X86_REX_W(b))
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/* REX.W overrides opnd_size */
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insn->opnd_bytes = 8;
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}
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}
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insn->rex_prefix.got = 1;
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/* Decode VEX prefix */
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b = peek_next(insn_byte_t, insn);
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attr = inat_get_opcode_attribute(b);
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if (inat_is_vex_prefix(attr)) {
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insn_byte_t b2 = peek_nbyte_next(insn_byte_t, insn, 1);
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if (!insn->x86_64) {
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/*
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* In 32-bits mode, if the [7:6] bits (mod bits of
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* ModRM) on the second byte are not 11b, it is
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* LDS or LES or BOUND.
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*/
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if (X86_MODRM_MOD(b2) != 3)
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goto vex_end;
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}
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insn_set_byte(&insn->vex_prefix, 0, b);
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insn_set_byte(&insn->vex_prefix, 1, b2);
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if (inat_is_evex_prefix(attr)) {
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b2 = peek_nbyte_next(insn_byte_t, insn, 2);
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insn_set_byte(&insn->vex_prefix, 2, b2);
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b2 = peek_nbyte_next(insn_byte_t, insn, 3);
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insn_set_byte(&insn->vex_prefix, 3, b2);
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insn->vex_prefix.nbytes = 4;
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insn->next_byte += 4;
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if (insn->x86_64 && X86_VEX_W(b2))
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/* VEX.W overrides opnd_size */
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insn->opnd_bytes = 8;
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} else if (inat_is_vex3_prefix(attr)) {
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b2 = peek_nbyte_next(insn_byte_t, insn, 2);
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insn_set_byte(&insn->vex_prefix, 2, b2);
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insn->vex_prefix.nbytes = 3;
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insn->next_byte += 3;
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if (insn->x86_64 && X86_VEX_W(b2))
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/* VEX.W overrides opnd_size */
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insn->opnd_bytes = 8;
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} else {
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/*
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* For VEX2, fake VEX3-like byte#2.
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* Makes it easier to decode vex.W, vex.vvvv,
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* vex.L and vex.pp. Masking with 0x7f sets vex.W == 0.
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*/
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insn_set_byte(&insn->vex_prefix, 2, b2 & 0x7f);
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insn->vex_prefix.nbytes = 2;
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insn->next_byte += 2;
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}
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}
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vex_end:
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insn->vex_prefix.got = 1;
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prefixes->got = 1;
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return 0;
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err_out:
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return -ENODATA;
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}
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/**
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* insn_get_opcode - collect opcode(s)
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* @insn: &struct insn containing instruction
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*
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* Populates @insn->opcode, updates @insn->next_byte to point past the
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* opcode byte(s), and set @insn->attr (except for groups).
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* If necessary, first collects any preceding (prefix) bytes.
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* Sets @insn->opcode.value = opcode1. No effect if @insn->opcode.got
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* is already 1.
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*
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* Returns:
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* 0: on success
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* < 0: on error
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*/
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int insn_get_opcode(struct insn *insn)
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{
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struct insn_field *opcode = &insn->opcode;
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int pfx_id, ret;
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insn_byte_t op;
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if (opcode->got)
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return 0;
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if (!insn->prefixes.got) {
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ret = insn_get_prefixes(insn);
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if (ret)
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return ret;
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}
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/* Get first opcode */
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op = get_next(insn_byte_t, insn);
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insn_set_byte(opcode, 0, op);
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opcode->nbytes = 1;
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/* Check if there is VEX prefix or not */
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if (insn_is_avx(insn)) {
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insn_byte_t m, p;
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m = insn_vex_m_bits(insn);
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p = insn_vex_p_bits(insn);
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insn->attr = inat_get_avx_attribute(op, m, p);
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if ((inat_must_evex(insn->attr) && !insn_is_evex(insn)) ||
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(!inat_accept_vex(insn->attr) &&
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!inat_is_group(insn->attr))) {
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/* This instruction is bad */
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insn->attr = 0;
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return -EINVAL;
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}
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/* VEX has only 1 byte for opcode */
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goto end;
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}
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insn->attr = inat_get_opcode_attribute(op);
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while (inat_is_escape(insn->attr)) {
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/* Get escaped opcode */
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op = get_next(insn_byte_t, insn);
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opcode->bytes[opcode->nbytes++] = op;
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pfx_id = insn_last_prefix_id(insn);
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insn->attr = inat_get_escape_attribute(op, pfx_id, insn->attr);
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}
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if (inat_must_vex(insn->attr)) {
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/* This instruction is bad */
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insn->attr = 0;
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return -EINVAL;
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}
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end:
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opcode->got = 1;
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return 0;
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err_out:
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return -ENODATA;
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}
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/**
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* insn_get_modrm - collect ModRM byte, if any
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* @insn: &struct insn containing instruction
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*
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* Populates @insn->modrm and updates @insn->next_byte to point past the
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* ModRM byte, if any. If necessary, first collects the preceding bytes
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* (prefixes and opcode(s)). No effect if @insn->modrm.got is already 1.
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*
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* Returns:
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* 0: on success
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* < 0: on error
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*/
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int insn_get_modrm(struct insn *insn)
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{
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struct insn_field *modrm = &insn->modrm;
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insn_byte_t pfx_id, mod;
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int ret;
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if (modrm->got)
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return 0;
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if (!insn->opcode.got) {
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ret = insn_get_opcode(insn);
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if (ret)
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return ret;
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}
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if (inat_has_modrm(insn->attr)) {
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mod = get_next(insn_byte_t, insn);
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insn_field_set(modrm, mod, 1);
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if (inat_is_group(insn->attr)) {
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pfx_id = insn_last_prefix_id(insn);
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insn->attr = inat_get_group_attribute(mod, pfx_id,
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insn->attr);
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if (insn_is_avx(insn) && !inat_accept_vex(insn->attr)) {
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/* Bad insn */
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insn->attr = 0;
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return -EINVAL;
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}
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}
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}
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if (insn->x86_64 && inat_is_force64(insn->attr))
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insn->opnd_bytes = 8;
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modrm->got = 1;
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return 0;
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err_out:
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return -ENODATA;
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}
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/**
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* insn_rip_relative() - Does instruction use RIP-relative addressing mode?
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* @insn: &struct insn containing instruction
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*
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* If necessary, first collects the instruction up to and including the
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* ModRM byte. No effect if @insn->x86_64 is 0.
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*/
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int insn_rip_relative(struct insn *insn)
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{
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struct insn_field *modrm = &insn->modrm;
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int ret;
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if (!insn->x86_64)
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return 0;
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if (!modrm->got) {
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ret = insn_get_modrm(insn);
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if (ret)
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return 0;
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}
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/*
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* For rip-relative instructions, the mod field (top 2 bits)
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* is zero and the r/m field (bottom 3 bits) is 0x5.
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*/
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return (modrm->nbytes && (modrm->bytes[0] & 0xc7) == 0x5);
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}
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/**
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* insn_get_sib() - Get the SIB byte of instruction
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* @insn: &struct insn containing instruction
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*
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* If necessary, first collects the instruction up to and including the
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* ModRM byte.
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*
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* Returns:
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* 0: if decoding succeeded
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* < 0: otherwise.
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*/
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int insn_get_sib(struct insn *insn)
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{
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insn_byte_t modrm;
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int ret;
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if (insn->sib.got)
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return 0;
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if (!insn->modrm.got) {
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ret = insn_get_modrm(insn);
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if (ret)
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return ret;
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}
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if (insn->modrm.nbytes) {
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modrm = insn->modrm.bytes[0];
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if (insn->addr_bytes != 2 &&
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X86_MODRM_MOD(modrm) != 3 && X86_MODRM_RM(modrm) == 4) {
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insn_field_set(&insn->sib,
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get_next(insn_byte_t, insn), 1);
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}
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}
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insn->sib.got = 1;
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return 0;
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err_out:
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return -ENODATA;
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}
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/**
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* insn_get_displacement() - Get the displacement of instruction
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* @insn: &struct insn containing instruction
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*
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* If necessary, first collects the instruction up to and including the
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* SIB byte.
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* Displacement value is sign-expanded.
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*
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* * Returns:
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* 0: if decoding succeeded
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* < 0: otherwise.
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*/
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int insn_get_displacement(struct insn *insn)
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{
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insn_byte_t mod, rm, base;
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int ret;
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if (insn->displacement.got)
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return 0;
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if (!insn->sib.got) {
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ret = insn_get_sib(insn);
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if (ret)
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return ret;
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}
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if (insn->modrm.nbytes) {
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/*
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* Interpreting the modrm byte:
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* mod = 00 - no displacement fields (exceptions below)
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* mod = 01 - 1-byte displacement field
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* mod = 10 - displacement field is 4 bytes, or 2 bytes if
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* address size = 2 (0x67 prefix in 32-bit mode)
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* mod = 11 - no memory operand
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*
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* If address size = 2...
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* mod = 00, r/m = 110 - displacement field is 2 bytes
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*
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* If address size != 2...
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* mod != 11, r/m = 100 - SIB byte exists
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* mod = 00, SIB base = 101 - displacement field is 4 bytes
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* mod = 00, r/m = 101 - rip-relative addressing, displacement
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* field is 4 bytes
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*/
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mod = X86_MODRM_MOD(insn->modrm.value);
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rm = X86_MODRM_RM(insn->modrm.value);
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base = X86_SIB_BASE(insn->sib.value);
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if (mod == 3)
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goto out;
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if (mod == 1) {
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insn_field_set(&insn->displacement,
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get_next(signed char, insn), 1);
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} else if (insn->addr_bytes == 2) {
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if ((mod == 0 && rm == 6) || mod == 2) {
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insn_field_set(&insn->displacement,
|
|
get_next(short, insn), 2);
|
|
}
|
|
} else {
|
|
if ((mod == 0 && rm == 5) || mod == 2 ||
|
|
(mod == 0 && base == 5)) {
|
|
insn_field_set(&insn->displacement,
|
|
get_next(int, insn), 4);
|
|
}
|
|
}
|
|
}
|
|
out:
|
|
insn->displacement.got = 1;
|
|
return 0;
|
|
|
|
err_out:
|
|
return -ENODATA;
|
|
}
|
|
|
|
/* Decode moffset16/32/64. Return 0 if failed */
|
|
static int __get_moffset(struct insn *insn)
|
|
{
|
|
switch (insn->addr_bytes) {
|
|
case 2:
|
|
insn_field_set(&insn->moffset1, get_next(short, insn), 2);
|
|
break;
|
|
case 4:
|
|
insn_field_set(&insn->moffset1, get_next(int, insn), 4);
|
|
break;
|
|
case 8:
|
|
insn_field_set(&insn->moffset1, get_next(int, insn), 4);
|
|
insn_field_set(&insn->moffset2, get_next(int, insn), 4);
|
|
break;
|
|
default: /* opnd_bytes must be modified manually */
|
|
goto err_out;
|
|
}
|
|
insn->moffset1.got = insn->moffset2.got = 1;
|
|
|
|
return 1;
|
|
|
|
err_out:
|
|
return 0;
|
|
}
|
|
|
|
/* Decode imm v32(Iz). Return 0 if failed */
|
|
static int __get_immv32(struct insn *insn)
|
|
{
|
|
switch (insn->opnd_bytes) {
|
|
case 2:
|
|
insn_field_set(&insn->immediate, get_next(short, insn), 2);
|
|
break;
|
|
case 4:
|
|
case 8:
|
|
insn_field_set(&insn->immediate, get_next(int, insn), 4);
|
|
break;
|
|
default: /* opnd_bytes must be modified manually */
|
|
goto err_out;
|
|
}
|
|
|
|
return 1;
|
|
|
|
err_out:
|
|
return 0;
|
|
}
|
|
|
|
/* Decode imm v64(Iv/Ov), Return 0 if failed */
|
|
static int __get_immv(struct insn *insn)
|
|
{
|
|
switch (insn->opnd_bytes) {
|
|
case 2:
|
|
insn_field_set(&insn->immediate1, get_next(short, insn), 2);
|
|
break;
|
|
case 4:
|
|
insn_field_set(&insn->immediate1, get_next(int, insn), 4);
|
|
insn->immediate1.nbytes = 4;
|
|
break;
|
|
case 8:
|
|
insn_field_set(&insn->immediate1, get_next(int, insn), 4);
|
|
insn_field_set(&insn->immediate2, get_next(int, insn), 4);
|
|
break;
|
|
default: /* opnd_bytes must be modified manually */
|
|
goto err_out;
|
|
}
|
|
insn->immediate1.got = insn->immediate2.got = 1;
|
|
|
|
return 1;
|
|
err_out:
|
|
return 0;
|
|
}
|
|
|
|
/* Decode ptr16:16/32(Ap) */
|
|
static int __get_immptr(struct insn *insn)
|
|
{
|
|
switch (insn->opnd_bytes) {
|
|
case 2:
|
|
insn_field_set(&insn->immediate1, get_next(short, insn), 2);
|
|
break;
|
|
case 4:
|
|
insn_field_set(&insn->immediate1, get_next(int, insn), 4);
|
|
break;
|
|
case 8:
|
|
/* ptr16:64 is not exist (no segment) */
|
|
return 0;
|
|
default: /* opnd_bytes must be modified manually */
|
|
goto err_out;
|
|
}
|
|
insn_field_set(&insn->immediate2, get_next(unsigned short, insn), 2);
|
|
insn->immediate1.got = insn->immediate2.got = 1;
|
|
|
|
return 1;
|
|
err_out:
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* insn_get_immediate() - Get the immediate in an instruction
|
|
* @insn: &struct insn containing instruction
|
|
*
|
|
* If necessary, first collects the instruction up to and including the
|
|
* displacement bytes.
|
|
* Basically, most of immediates are sign-expanded. Unsigned-value can be
|
|
* computed by bit masking with ((1 << (nbytes * 8)) - 1)
|
|
*
|
|
* Returns:
|
|
* 0: on success
|
|
* < 0: on error
|
|
*/
|
|
int insn_get_immediate(struct insn *insn)
|
|
{
|
|
int ret;
|
|
|
|
if (insn->immediate.got)
|
|
return 0;
|
|
|
|
if (!insn->displacement.got) {
|
|
ret = insn_get_displacement(insn);
|
|
if (ret)
|
|
return ret;
|
|
}
|
|
|
|
if (inat_has_moffset(insn->attr)) {
|
|
if (!__get_moffset(insn))
|
|
goto err_out;
|
|
goto done;
|
|
}
|
|
|
|
if (!inat_has_immediate(insn->attr))
|
|
/* no immediates */
|
|
goto done;
|
|
|
|
switch (inat_immediate_size(insn->attr)) {
|
|
case INAT_IMM_BYTE:
|
|
insn_field_set(&insn->immediate, get_next(signed char, insn), 1);
|
|
break;
|
|
case INAT_IMM_WORD:
|
|
insn_field_set(&insn->immediate, get_next(short, insn), 2);
|
|
break;
|
|
case INAT_IMM_DWORD:
|
|
insn_field_set(&insn->immediate, get_next(int, insn), 4);
|
|
break;
|
|
case INAT_IMM_QWORD:
|
|
insn_field_set(&insn->immediate1, get_next(int, insn), 4);
|
|
insn_field_set(&insn->immediate2, get_next(int, insn), 4);
|
|
break;
|
|
case INAT_IMM_PTR:
|
|
if (!__get_immptr(insn))
|
|
goto err_out;
|
|
break;
|
|
case INAT_IMM_VWORD32:
|
|
if (!__get_immv32(insn))
|
|
goto err_out;
|
|
break;
|
|
case INAT_IMM_VWORD:
|
|
if (!__get_immv(insn))
|
|
goto err_out;
|
|
break;
|
|
default:
|
|
/* Here, insn must have an immediate, but failed */
|
|
goto err_out;
|
|
}
|
|
if (inat_has_second_immediate(insn->attr)) {
|
|
insn_field_set(&insn->immediate2, get_next(signed char, insn), 1);
|
|
}
|
|
done:
|
|
insn->immediate.got = 1;
|
|
return 0;
|
|
|
|
err_out:
|
|
return -ENODATA;
|
|
}
|
|
|
|
/**
|
|
* insn_get_length() - Get the length of instruction
|
|
* @insn: &struct insn containing instruction
|
|
*
|
|
* If necessary, first collects the instruction up to and including the
|
|
* immediates bytes.
|
|
*
|
|
* Returns:
|
|
* - 0 on success
|
|
* - < 0 on error
|
|
*/
|
|
int insn_get_length(struct insn *insn)
|
|
{
|
|
int ret;
|
|
|
|
if (insn->length)
|
|
return 0;
|
|
|
|
if (!insn->immediate.got) {
|
|
ret = insn_get_immediate(insn);
|
|
if (ret)
|
|
return ret;
|
|
}
|
|
|
|
insn->length = (unsigned char)((unsigned long)insn->next_byte
|
|
- (unsigned long)insn->kaddr);
|
|
|
|
return 0;
|
|
}
|
|
|
|
/* Ensure this instruction is decoded completely */
|
|
static inline int insn_complete(struct insn *insn)
|
|
{
|
|
return insn->opcode.got && insn->modrm.got && insn->sib.got &&
|
|
insn->displacement.got && insn->immediate.got;
|
|
}
|
|
|
|
/**
|
|
* insn_decode() - Decode an x86 instruction
|
|
* @insn: &struct insn to be initialized
|
|
* @kaddr: address (in kernel memory) of instruction (or copy thereof)
|
|
* @buf_len: length of the insn buffer at @kaddr
|
|
* @m: insn mode, see enum insn_mode
|
|
*
|
|
* Returns:
|
|
* 0: if decoding succeeded
|
|
* < 0: otherwise.
|
|
*/
|
|
int insn_decode(struct insn *insn, const void *kaddr, int buf_len, enum insn_mode m)
|
|
{
|
|
int ret;
|
|
|
|
/* #define INSN_MODE_KERN -1 __ignore_sync_check__ mode is only valid in the kernel */
|
|
|
|
if (m == INSN_MODE_KERN)
|
|
insn_init(insn, kaddr, buf_len, IS_ENABLED(CONFIG_X86_64));
|
|
else
|
|
insn_init(insn, kaddr, buf_len, m == INSN_MODE_64);
|
|
|
|
ret = insn_get_length(insn);
|
|
if (ret)
|
|
return ret;
|
|
|
|
if (insn_complete(insn))
|
|
return 0;
|
|
|
|
return -EINVAL;
|
|
}
|