// SPDX-License-Identifier: GPL-2.0-only
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/*
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* arch/arm/probes/kprobes/checkers-thumb.c
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*
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* Copyright (C) 2014 Huawei Inc.
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*/
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#include <linux/kernel.h>
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#include "../decode.h"
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#include "../decode-thumb.h"
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#include "checkers.h"
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static enum probes_insn __kprobes t32_check_stack(probes_opcode_t insn,
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struct arch_probes_insn *asi,
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const struct decode_header *h)
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{
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/*
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* PROBES_T32_LDMSTM, PROBES_T32_LDRDSTRD and PROBES_T32_LDRSTR
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* may get here. Simply mark all normal insns as STACK_USE_NONE.
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*/
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static const union decode_item table[] = {
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/*
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* First, filter out all ldr insns to make our life easier.
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* Following load insns may come here:
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* LDM, LDRD, LDR.
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* In T32 encoding, bit 20 is enough for distinguishing
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* load and store. All load insns have this bit set, when
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* all store insns have this bit clear.
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*/
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DECODE_CUSTOM (0x00100000, 0x00100000, STACK_USE_NONE),
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/*
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* Mark all 'STR{,B,H}, Rt, [Rn, Rm]' as STACK_USE_UNKNOWN
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* if Rn or Rm is SP. T32 doesn't encode STRD.
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*/
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/* xx | Rn | Rt | | Rm |*/
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/* STR (register) 1111 1000 0100 xxxx xxxx 0000 00xx xxxx */
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/* STRB (register) 1111 1000 0000 xxxx xxxx 0000 00xx xxxx */
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/* STRH (register) 1111 1000 0010 xxxx xxxx 0000 00xx xxxx */
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/* INVALID INSN 1111 1000 0110 xxxx xxxx 0000 00xx xxxx */
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/* By Introducing INVALID INSN, bit 21 and 22 can be ignored. */
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DECODE_OR (0xff9f0fc0, 0xf80d0000),
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DECODE_CUSTOM (0xff900fcf, 0xf800000d, STACK_USE_UNKNOWN),
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/* xx | Rn | Rt | PUW| imm8 |*/
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/* STR (imm 8) 1111 1000 0100 1101 xxxx 110x xxxx xxxx */
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/* STRB (imm 8) 1111 1000 0000 1101 xxxx 110x xxxx xxxx */
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/* STRH (imm 8) 1111 1000 0010 1101 xxxx 110x xxxx xxxx */
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/* INVALID INSN 1111 1000 0110 1101 xxxx 110x xxxx xxxx */
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/* Only consider U == 0 and P == 1: strx rx, [sp, #-<imm>] */
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DECODE_CUSTOM (0xff9f0e00, 0xf80d0c00, STACK_USE_FIXED_0XX),
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/* For STR{,B,H} (imm 12), offset is always positive, so ignore them. */
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/* P U W | Rn | Rt | Rt2| imm8 |*/
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/* STRD (immediate) 1110 1001 01x0 1101 xxxx xxxx xxxx xxxx */
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/*
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* Only consider U == 0 and P == 1.
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* Also note that STRD in T32 encoding is special:
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* imm = ZeroExtend(imm8:'00', 32)
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*/
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DECODE_CUSTOM (0xffdf0000, 0xe94d0000, STACK_USE_T32STRD),
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/* | Rn | */
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/* STMDB 1110 1001 00x0 1101 xxxx xxxx xxxx xxxx */
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DECODE_CUSTOM (0xffdf0000, 0xe90d0000, STACK_USE_STMDX),
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/* fall through */
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DECODE_CUSTOM (0, 0, STACK_USE_NONE),
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DECODE_END
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};
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return probes_decode_insn(insn, asi, table, false, false, stack_check_actions, NULL);
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}
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const struct decode_checker t32_stack_checker[NUM_PROBES_T32_ACTIONS] = {
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[PROBES_T32_LDMSTM] = {.checker = t32_check_stack},
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[PROBES_T32_LDRDSTRD] = {.checker = t32_check_stack},
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[PROBES_T32_LDRSTR] = {.checker = t32_check_stack},
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};
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/*
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* See following comments. This insn must be 'push'.
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*/
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static enum probes_insn __kprobes t16_check_stack(probes_opcode_t insn,
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struct arch_probes_insn *asi,
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const struct decode_header *h)
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{
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unsigned int reglist = insn & 0x1ff;
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asi->stack_space = hweight32(reglist) * 4;
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return INSN_GOOD;
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}
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/*
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* T16 encoding is simple: only the 'push' insn can need extra stack space.
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* Other insns, like str, can only use r0-r7 as Rn.
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*/
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const struct decode_checker t16_stack_checker[NUM_PROBES_T16_ACTIONS] = {
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[PROBES_T16_PUSH] = {.checker = t16_check_stack},
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};
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