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/*
* arch/arm/probes/kprobes/checkers-thumb.c
*
* Copyright (C) 2014 Huawei Inc.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* 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.
*/
#include <linux/kernel.h>
#include "../decode.h"
#include "../decode-thumb.h"
#include "checkers.h"
static enum probes_insn __kprobes t32_check_stack(probes_opcode_t insn,
struct arch_probes_insn *asi,
const struct decode_header *h)
{
/*
* PROBES_T32_LDMSTM, PROBES_T32_LDRDSTRD and PROBES_T32_LDRSTR
* may get here. Simply mark all normal insns as STACK_USE_NONE.
*/
static const union decode_item table[] = {
/*
* First, filter out all ldr insns to make our life easier.
* Following load insns may come here:
* LDM, LDRD, LDR.
* In T32 encoding, bit 20 is enough for distinguishing
* load and store. All load insns have this bit set, when
* all store insns have this bit clear.
*/
DECODE_CUSTOM (0x00100000, 0x00100000, STACK_USE_NONE),
/*
* Mark all 'STR{,B,H}, Rt, [Rn, Rm]' as STACK_USE_UNKNOWN
* if Rn or Rm is SP. T32 doesn't encode STRD.
*/
/* xx | Rn | Rt | | Rm |*/
/* STR (register) 1111 1000 0100 xxxx xxxx 0000 00xx xxxx */
/* STRB (register) 1111 1000 0000 xxxx xxxx 0000 00xx xxxx */
/* STRH (register) 1111 1000 0010 xxxx xxxx 0000 00xx xxxx */
/* INVALID INSN 1111 1000 0110 xxxx xxxx 0000 00xx xxxx */
/* By Introducing INVALID INSN, bit 21 and 22 can be ignored. */
DECODE_OR (0xff9f0fc0, 0xf80d0000),
DECODE_CUSTOM (0xff900fcf, 0xf800000d, STACK_USE_UNKNOWN),
/* xx | Rn | Rt | PUW| imm8 |*/
/* STR (imm 8) 1111 1000 0100 1101 xxxx 110x xxxx xxxx */
/* STRB (imm 8) 1111 1000 0000 1101 xxxx 110x xxxx xxxx */
/* STRH (imm 8) 1111 1000 0010 1101 xxxx 110x xxxx xxxx */
/* INVALID INSN 1111 1000 0110 1101 xxxx 110x xxxx xxxx */
/* Only consider U == 0 and P == 1: strx rx, [sp, #-<imm>] */
DECODE_CUSTOM (0xff9f0e00, 0xf80d0c00, STACK_USE_FIXED_0XX),
/* For STR{,B,H} (imm 12), offset is always positive, so ignore them. */
/* P U W | Rn | Rt | Rt2| imm8 |*/
/* STRD (immediate) 1110 1001 01x0 1101 xxxx xxxx xxxx xxxx */
/*
* Only consider U == 0 and P == 1.
* Also note that STRD in T32 encoding is special:
* imm = ZeroExtend(imm8:'00', 32)
*/
DECODE_CUSTOM (0xffdf0000, 0xe94d0000, STACK_USE_T32STRD),
/* | Rn | */
/* STMDB 1110 1001 00x0 1101 xxxx xxxx xxxx xxxx */
DECODE_CUSTOM (0xffdf0000, 0xe90d0000, STACK_USE_STMDX),
/* fall through */
DECODE_CUSTOM (0, 0, STACK_USE_NONE),
DECODE_END
};
return probes_decode_insn(insn, asi, table, false, false, stack_check_actions, NULL);
}
const struct decode_checker t32_stack_checker[NUM_PROBES_T32_ACTIONS] = {
[PROBES_T32_LDMSTM] = {.checker = t32_check_stack},
[PROBES_T32_LDRDSTRD] = {.checker = t32_check_stack},
[PROBES_T32_LDRSTR] = {.checker = t32_check_stack},
};
/*
* See following comments. This insn must be 'push'.
*/
static enum probes_insn __kprobes t16_check_stack(probes_opcode_t insn,
struct arch_probes_insn *asi,
const struct decode_header *h)
{
unsigned int reglist = insn & 0x1ff;
asi->stack_space = hweight32(reglist) * 4;
return INSN_GOOD;
}
/*
* T16 encoding is simple: only the 'push' insn can need extra stack space.
* Other insns, like str, can only use r0-r7 as Rn.
*/
const struct decode_checker t16_stack_checker[NUM_PROBES_T16_ACTIONS] = {
[PROBES_T16_PUSH] = {.checker = t16_check_stack},
};
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