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-rw-r--r--arch/x86/lib/insn.c753
1 files changed, 753 insertions, 0 deletions
diff --git a/arch/x86/lib/insn.c b/arch/x86/lib/insn.c
new file mode 100644
index 000000000..24e89239d
--- /dev/null
+++ b/arch/x86/lib/insn.c
@@ -0,0 +1,753 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * x86 instruction analysis
+ *
+ * Copyright (C) IBM Corporation, 2002, 2004, 2009
+ */
+
+#ifdef __KERNEL__
+#include <linux/string.h>
+#else
+#include <string.h>
+#endif
+#include <asm/inat.h> /*__ignore_sync_check__ */
+#include <asm/insn.h> /* __ignore_sync_check__ */
+
+#include <linux/errno.h>
+#include <linux/kconfig.h>
+
+#include <asm/emulate_prefix.h> /* __ignore_sync_check__ */
+
+/* Verify next sizeof(t) bytes can be on the same instruction */
+#define validate_next(t, insn, n) \
+ ((insn)->next_byte + sizeof(t) + n <= (insn)->end_kaddr)
+
+#define __get_next(t, insn) \
+ ({ t r = *(t*)insn->next_byte; insn->next_byte += sizeof(t); r; })
+
+#define __peek_nbyte_next(t, insn, n) \
+ ({ t r = *(t*)((insn)->next_byte + n); r; })
+
+#define get_next(t, insn) \
+ ({ if (unlikely(!validate_next(t, insn, 0))) goto err_out; __get_next(t, insn); })
+
+#define peek_nbyte_next(t, insn, n) \
+ ({ if (unlikely(!validate_next(t, insn, n))) goto err_out; __peek_nbyte_next(t, insn, n); })
+
+#define peek_next(t, insn) peek_nbyte_next(t, insn, 0)
+
+/**
+ * insn_init() - initialize struct insn
+ * @insn: &struct insn to be initialized
+ * @kaddr: address (in kernel memory) of instruction (or copy thereof)
+ * @x86_64: !0 for 64-bit kernel or 64-bit app
+ */
+void insn_init(struct insn *insn, const void *kaddr, int buf_len, int x86_64)
+{
+ /*
+ * Instructions longer than MAX_INSN_SIZE (15 bytes) are invalid
+ * even if the input buffer is long enough to hold them.
+ */
+ if (buf_len > MAX_INSN_SIZE)
+ buf_len = MAX_INSN_SIZE;
+
+ memset(insn, 0, sizeof(*insn));
+ insn->kaddr = kaddr;
+ insn->end_kaddr = kaddr + buf_len;
+ insn->next_byte = kaddr;
+ insn->x86_64 = x86_64 ? 1 : 0;
+ insn->opnd_bytes = 4;
+ if (x86_64)
+ insn->addr_bytes = 8;
+ else
+ insn->addr_bytes = 4;
+}
+
+static const insn_byte_t xen_prefix[] = { __XEN_EMULATE_PREFIX };
+static const insn_byte_t kvm_prefix[] = { __KVM_EMULATE_PREFIX };
+
+static int __insn_get_emulate_prefix(struct insn *insn,
+ const insn_byte_t *prefix, size_t len)
+{
+ size_t i;
+
+ for (i = 0; i < len; i++) {
+ if (peek_nbyte_next(insn_byte_t, insn, i) != prefix[i])
+ goto err_out;
+ }
+
+ insn->emulate_prefix_size = len;
+ insn->next_byte += len;
+
+ return 1;
+
+err_out:
+ return 0;
+}
+
+static void insn_get_emulate_prefix(struct insn *insn)
+{
+ if (__insn_get_emulate_prefix(insn, xen_prefix, sizeof(xen_prefix)))
+ return;
+
+ __insn_get_emulate_prefix(insn, kvm_prefix, sizeof(kvm_prefix));
+}
+
+/**
+ * insn_get_prefixes - scan x86 instruction prefix bytes
+ * @insn: &struct insn containing instruction
+ *
+ * Populates the @insn->prefixes bitmap, and updates @insn->next_byte
+ * to point to the (first) opcode. No effect if @insn->prefixes.got
+ * is already set.
+ *
+ * * Returns:
+ * 0: on success
+ * < 0: on error
+ */
+int insn_get_prefixes(struct insn *insn)
+{
+ struct insn_field *prefixes = &insn->prefixes;
+ insn_attr_t attr;
+ insn_byte_t b, lb;
+ int i, nb;
+
+ if (prefixes->got)
+ return 0;
+
+ insn_get_emulate_prefix(insn);
+
+ nb = 0;
+ lb = 0;
+ b = peek_next(insn_byte_t, insn);
+ attr = inat_get_opcode_attribute(b);
+ while (inat_is_legacy_prefix(attr)) {
+ /* Skip if same prefix */
+ for (i = 0; i < nb; i++)
+ if (prefixes->bytes[i] == b)
+ goto found;
+ if (nb == 4)
+ /* Invalid instruction */
+ break;
+ prefixes->bytes[nb++] = b;
+ if (inat_is_address_size_prefix(attr)) {
+ /* address size switches 2/4 or 4/8 */
+ if (insn->x86_64)
+ insn->addr_bytes ^= 12;
+ else
+ insn->addr_bytes ^= 6;
+ } else if (inat_is_operand_size_prefix(attr)) {
+ /* oprand size switches 2/4 */
+ insn->opnd_bytes ^= 6;
+ }
+found:
+ prefixes->nbytes++;
+ insn->next_byte++;
+ lb = b;
+ b = peek_next(insn_byte_t, insn);
+ attr = inat_get_opcode_attribute(b);
+ }
+ /* Set the last prefix */
+ if (lb && lb != insn->prefixes.bytes[3]) {
+ if (unlikely(insn->prefixes.bytes[3])) {
+ /* Swap the last prefix */
+ b = insn->prefixes.bytes[3];
+ for (i = 0; i < nb; i++)
+ if (prefixes->bytes[i] == lb)
+ prefixes->bytes[i] = b;
+ }
+ insn->prefixes.bytes[3] = lb;
+ }
+
+ /* Decode REX prefix */
+ if (insn->x86_64) {
+ b = peek_next(insn_byte_t, insn);
+ attr = inat_get_opcode_attribute(b);
+ if (inat_is_rex_prefix(attr)) {
+ insn->rex_prefix.value = b;
+ insn->rex_prefix.nbytes = 1;
+ insn->next_byte++;
+ if (X86_REX_W(b))
+ /* REX.W overrides opnd_size */
+ insn->opnd_bytes = 8;
+ }
+ }
+ insn->rex_prefix.got = 1;
+
+ /* Decode VEX prefix */
+ b = peek_next(insn_byte_t, insn);
+ attr = inat_get_opcode_attribute(b);
+ if (inat_is_vex_prefix(attr)) {
+ insn_byte_t b2 = peek_nbyte_next(insn_byte_t, insn, 1);
+ if (!insn->x86_64) {
+ /*
+ * In 32-bits mode, if the [7:6] bits (mod bits of
+ * ModRM) on the second byte are not 11b, it is
+ * LDS or LES or BOUND.
+ */
+ if (X86_MODRM_MOD(b2) != 3)
+ goto vex_end;
+ }
+ insn->vex_prefix.bytes[0] = b;
+ insn->vex_prefix.bytes[1] = b2;
+ if (inat_is_evex_prefix(attr)) {
+ b2 = peek_nbyte_next(insn_byte_t, insn, 2);
+ insn->vex_prefix.bytes[2] = b2;
+ b2 = peek_nbyte_next(insn_byte_t, insn, 3);
+ insn->vex_prefix.bytes[3] = b2;
+ insn->vex_prefix.nbytes = 4;
+ insn->next_byte += 4;
+ if (insn->x86_64 && X86_VEX_W(b2))
+ /* VEX.W overrides opnd_size */
+ insn->opnd_bytes = 8;
+ } else if (inat_is_vex3_prefix(attr)) {
+ b2 = peek_nbyte_next(insn_byte_t, insn, 2);
+ insn->vex_prefix.bytes[2] = b2;
+ insn->vex_prefix.nbytes = 3;
+ insn->next_byte += 3;
+ if (insn->x86_64 && X86_VEX_W(b2))
+ /* VEX.W overrides opnd_size */
+ insn->opnd_bytes = 8;
+ } else {
+ /*
+ * For VEX2, fake VEX3-like byte#2.
+ * Makes it easier to decode vex.W, vex.vvvv,
+ * vex.L and vex.pp. Masking with 0x7f sets vex.W == 0.
+ */
+ insn->vex_prefix.bytes[2] = b2 & 0x7f;
+ insn->vex_prefix.nbytes = 2;
+ insn->next_byte += 2;
+ }
+ }
+vex_end:
+ insn->vex_prefix.got = 1;
+
+ prefixes->got = 1;
+
+ return 0;
+
+err_out:
+ return -ENODATA;
+}
+
+/**
+ * insn_get_opcode - collect opcode(s)
+ * @insn: &struct insn containing instruction
+ *
+ * Populates @insn->opcode, updates @insn->next_byte to point past the
+ * opcode byte(s), and set @insn->attr (except for groups).
+ * If necessary, first collects any preceding (prefix) bytes.
+ * Sets @insn->opcode.value = opcode1. No effect if @insn->opcode.got
+ * is already 1.
+ *
+ * Returns:
+ * 0: on success
+ * < 0: on error
+ */
+int insn_get_opcode(struct insn *insn)
+{
+ struct insn_field *opcode = &insn->opcode;
+ int pfx_id, ret;
+ insn_byte_t op;
+
+ if (opcode->got)
+ return 0;
+
+ if (!insn->prefixes.got) {
+ ret = insn_get_prefixes(insn);
+ if (ret)
+ return ret;
+ }
+
+ /* Get first opcode */
+ op = get_next(insn_byte_t, insn);
+ opcode->bytes[0] = op;
+ opcode->nbytes = 1;
+
+ /* Check if there is VEX prefix or not */
+ if (insn_is_avx(insn)) {
+ insn_byte_t m, p;
+ m = insn_vex_m_bits(insn);
+ p = insn_vex_p_bits(insn);
+ insn->attr = inat_get_avx_attribute(op, m, p);
+ if ((inat_must_evex(insn->attr) && !insn_is_evex(insn)) ||
+ (!inat_accept_vex(insn->attr) &&
+ !inat_is_group(insn->attr))) {
+ /* This instruction is bad */
+ insn->attr = 0;
+ return -EINVAL;
+ }
+ /* VEX has only 1 byte for opcode */
+ goto end;
+ }
+
+ insn->attr = inat_get_opcode_attribute(op);
+ while (inat_is_escape(insn->attr)) {
+ /* Get escaped opcode */
+ op = get_next(insn_byte_t, insn);
+ opcode->bytes[opcode->nbytes++] = op;
+ pfx_id = insn_last_prefix_id(insn);
+ insn->attr = inat_get_escape_attribute(op, pfx_id, insn->attr);
+ }
+
+ if (inat_must_vex(insn->attr)) {
+ /* This instruction is bad */
+ insn->attr = 0;
+ return -EINVAL;
+ }
+end:
+ opcode->got = 1;
+ return 0;
+
+err_out:
+ return -ENODATA;
+}
+
+/**
+ * insn_get_modrm - collect ModRM byte, if any
+ * @insn: &struct insn containing instruction
+ *
+ * Populates @insn->modrm and updates @insn->next_byte to point past the
+ * ModRM byte, if any. If necessary, first collects the preceding bytes
+ * (prefixes and opcode(s)). No effect if @insn->modrm.got is already 1.
+ *
+ * Returns:
+ * 0: on success
+ * < 0: on error
+ */
+int insn_get_modrm(struct insn *insn)
+{
+ struct insn_field *modrm = &insn->modrm;
+ insn_byte_t pfx_id, mod;
+ int ret;
+
+ if (modrm->got)
+ return 0;
+
+ if (!insn->opcode.got) {
+ ret = insn_get_opcode(insn);
+ if (ret)
+ return ret;
+ }
+
+ if (inat_has_modrm(insn->attr)) {
+ mod = get_next(insn_byte_t, insn);
+ modrm->value = mod;
+ modrm->nbytes = 1;
+ if (inat_is_group(insn->attr)) {
+ pfx_id = insn_last_prefix_id(insn);
+ insn->attr = inat_get_group_attribute(mod, pfx_id,
+ insn->attr);
+ if (insn_is_avx(insn) && !inat_accept_vex(insn->attr)) {
+ /* Bad insn */
+ insn->attr = 0;
+ return -EINVAL;
+ }
+ }
+ }
+
+ if (insn->x86_64 && inat_is_force64(insn->attr))
+ insn->opnd_bytes = 8;
+
+ modrm->got = 1;
+ return 0;
+
+err_out:
+ return -ENODATA;
+}
+
+
+/**
+ * insn_rip_relative() - Does instruction use RIP-relative addressing mode?
+ * @insn: &struct insn containing instruction
+ *
+ * If necessary, first collects the instruction up to and including the
+ * ModRM byte. No effect if @insn->x86_64 is 0.
+ */
+int insn_rip_relative(struct insn *insn)
+{
+ struct insn_field *modrm = &insn->modrm;
+ int ret;
+
+ if (!insn->x86_64)
+ return 0;
+
+ if (!modrm->got) {
+ ret = insn_get_modrm(insn);
+ if (ret)
+ return 0;
+ }
+ /*
+ * For rip-relative instructions, the mod field (top 2 bits)
+ * is zero and the r/m field (bottom 3 bits) is 0x5.
+ */
+ return (modrm->nbytes && (modrm->value & 0xc7) == 0x5);
+}
+
+/**
+ * insn_get_sib() - Get the SIB byte of instruction
+ * @insn: &struct insn containing instruction
+ *
+ * If necessary, first collects the instruction up to and including the
+ * ModRM byte.
+ *
+ * Returns:
+ * 0: if decoding succeeded
+ * < 0: otherwise.
+ */
+int insn_get_sib(struct insn *insn)
+{
+ insn_byte_t modrm;
+ int ret;
+
+ if (insn->sib.got)
+ return 0;
+
+ if (!insn->modrm.got) {
+ ret = insn_get_modrm(insn);
+ if (ret)
+ return ret;
+ }
+
+ if (insn->modrm.nbytes) {
+ modrm = (insn_byte_t)insn->modrm.value;
+ if (insn->addr_bytes != 2 &&
+ X86_MODRM_MOD(modrm) != 3 && X86_MODRM_RM(modrm) == 4) {
+ insn->sib.value = get_next(insn_byte_t, insn);
+ insn->sib.nbytes = 1;
+ }
+ }
+ insn->sib.got = 1;
+
+ return 0;
+
+err_out:
+ return -ENODATA;
+}
+
+
+/**
+ * insn_get_displacement() - Get the displacement of instruction
+ * @insn: &struct insn containing instruction
+ *
+ * If necessary, first collects the instruction up to and including the
+ * SIB byte.
+ * Displacement value is sign-expanded.
+ *
+ * * Returns:
+ * 0: if decoding succeeded
+ * < 0: otherwise.
+ */
+int insn_get_displacement(struct insn *insn)
+{
+ insn_byte_t mod, rm, base;
+ int ret;
+
+ if (insn->displacement.got)
+ return 0;
+
+ if (!insn->sib.got) {
+ ret = insn_get_sib(insn);
+ if (ret)
+ return ret;
+ }
+
+ if (insn->modrm.nbytes) {
+ /*
+ * Interpreting the modrm byte:
+ * mod = 00 - no displacement fields (exceptions below)
+ * mod = 01 - 1-byte displacement field
+ * mod = 10 - displacement field is 4 bytes, or 2 bytes if
+ * address size = 2 (0x67 prefix in 32-bit mode)
+ * mod = 11 - no memory operand
+ *
+ * If address size = 2...
+ * mod = 00, r/m = 110 - displacement field is 2 bytes
+ *
+ * If address size != 2...
+ * mod != 11, r/m = 100 - SIB byte exists
+ * mod = 00, SIB base = 101 - displacement field is 4 bytes
+ * mod = 00, r/m = 101 - rip-relative addressing, displacement
+ * field is 4 bytes
+ */
+ mod = X86_MODRM_MOD(insn->modrm.value);
+ rm = X86_MODRM_RM(insn->modrm.value);
+ base = X86_SIB_BASE(insn->sib.value);
+ if (mod == 3)
+ goto out;
+ if (mod == 1) {
+ insn->displacement.value = get_next(signed char, insn);
+ insn->displacement.nbytes = 1;
+ } else if (insn->addr_bytes == 2) {
+ if ((mod == 0 && rm == 6) || mod == 2) {
+ insn->displacement.value =
+ get_next(short, insn);
+ insn->displacement.nbytes = 2;
+ }
+ } else {
+ if ((mod == 0 && rm == 5) || mod == 2 ||
+ (mod == 0 && base == 5)) {
+ insn->displacement.value = get_next(int, insn);
+ insn->displacement.nbytes = 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->moffset1.value = get_next(short, insn);
+ insn->moffset1.nbytes = 2;
+ break;
+ case 4:
+ insn->moffset1.value = get_next(int, insn);
+ insn->moffset1.nbytes = 4;
+ break;
+ case 8:
+ insn->moffset1.value = get_next(int, insn);
+ insn->moffset1.nbytes = 4;
+ insn->moffset2.value = get_next(int, insn);
+ insn->moffset2.nbytes = 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->immediate.value = get_next(short, insn);
+ insn->immediate.nbytes = 2;
+ break;
+ case 4:
+ case 8:
+ insn->immediate.value = get_next(int, insn);
+ insn->immediate.nbytes = 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->immediate1.value = get_next(short, insn);
+ insn->immediate1.nbytes = 2;
+ break;
+ case 4:
+ insn->immediate1.value = get_next(int, insn);
+ insn->immediate1.nbytes = 4;
+ break;
+ case 8:
+ insn->immediate1.value = get_next(int, insn);
+ insn->immediate1.nbytes = 4;
+ insn->immediate2.value = get_next(int, insn);
+ insn->immediate2.nbytes = 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->immediate1.value = get_next(short, insn);
+ insn->immediate1.nbytes = 2;
+ break;
+ case 4:
+ insn->immediate1.value = get_next(int, insn);
+ insn->immediate1.nbytes = 4;
+ break;
+ case 8:
+ /* ptr16:64 is not exist (no segment) */
+ return 0;
+ default: /* opnd_bytes must be modified manually */
+ goto err_out;
+ }
+ insn->immediate2.value = get_next(unsigned short, insn);
+ insn->immediate2.nbytes = 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->immediate.value = get_next(signed char, insn);
+ insn->immediate.nbytes = 1;
+ break;
+ case INAT_IMM_WORD:
+ insn->immediate.value = get_next(short, insn);
+ insn->immediate.nbytes = 2;
+ break;
+ case INAT_IMM_DWORD:
+ insn->immediate.value = get_next(int, insn);
+ insn->immediate.nbytes = 4;
+ break;
+ case INAT_IMM_QWORD:
+ insn->immediate1.value = get_next(int, insn);
+ insn->immediate1.nbytes = 4;
+ insn->immediate2.value = get_next(int, insn);
+ insn->immediate2.nbytes = 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->immediate2.value = get_next(signed char, insn);
+ insn->immediate2.nbytes = 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;
+}
+
+/**
+ * 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;
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-12 17:22:18 +0000