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/*
* arch/arm/probes/kprobes/checkers-arm.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-arm.h"
#include "checkers.h"
static enum probes_insn __kprobes arm_check_stack(probes_opcode_t insn,
struct arch_probes_insn *asi,
const struct decode_header *h)
{
/*
* PROBES_LDRSTRD, PROBES_LDMSTM, PROBES_STORE,
* PROBES_STORE_EXTRA may get here. Simply mark all normal
* insns as STACK_USE_NONE.
*/
static const union decode_item table[] = {
/*
* 'STR{,D,B,H}, Rt, [Rn, Rm]' should be marked as UNKNOWN
* if Rn or Rm is SP.
* x
* STR (register) cccc 011x x0x0 xxxx xxxx xxxx xxxx xxxx
* STRB (register) cccc 011x x1x0 xxxx xxxx xxxx xxxx xxxx
*/
DECODE_OR (0x0e10000f, 0x0600000d),
DECODE_OR (0x0e1f0000, 0x060d0000),
/*
* x
* STRD (register) cccc 000x x0x0 xxxx xxxx xxxx 1111 xxxx
* STRH (register) cccc 000x x0x0 xxxx xxxx xxxx 1011 xxxx
*/
DECODE_OR (0x0e5000bf, 0x000000bd),
DECODE_CUSTOM (0x0e5f00b0, 0x000d00b0, STACK_USE_UNKNOWN),
/*
* For PROBES_LDMSTM, only stmdx sp, [...] need to examine
*
* Bit B/A (bit 24) encodes arithmetic operation order. 1 means
* before, 0 means after.
* Bit I/D (bit 23) encodes arithmetic operation. 1 means
* increment, 0 means decrement.
*
* So:
* B I
* / /
* A D | Rn |
* STMDX SP, [...] cccc 100x 00x0 xxxx xxxx xxxx xxxx xxxx
*/
DECODE_CUSTOM (0x0edf0000, 0x080d0000, STACK_USE_STMDX),
/* P U W | Rn | Rt | imm12 |*/
/* STR (immediate) cccc 010x x0x0 1101 xxxx xxxx xxxx xxxx */
/* STRB (immediate) cccc 010x x1x0 1101 xxxx xxxx xxxx xxxx */
/* P U W | Rn | Rt |imm4| |imm4|*/
/* STRD (immediate) cccc 000x x1x0 1101 xxxx xxxx 1111 xxxx */
/* STRH (immediate) cccc 000x x1x0 1101 xxxx xxxx 1011 xxxx */
/*
* index = (P == '1'); add = (U == '1').
* Above insns with:
* index == 0 (str{,d,h} rx, [sp], #+/-imm) or
* add == 1 (str{,d,h} rx, [sp, #+<imm>])
* should be STACK_USE_NONE.
* Only str{,b,d,h} rx,[sp,#-n] (P == 1 and U == 0) are
* required to be examined.
*/
/* STR{,B} Rt,[SP,#-n] cccc 0101 0xx0 1101 xxxx xxxx xxxx xxxx */
DECODE_CUSTOM (0x0f9f0000, 0x050d0000, STACK_USE_FIXED_XXX),
/* STR{D,H} Rt,[SP,#-n] cccc 0001 01x0 1101 xxxx xxxx 1x11 xxxx */
DECODE_CUSTOM (0x0fdf00b0, 0x014d00b0, STACK_USE_FIXED_X0X),
/* 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 arm_stack_checker[NUM_PROBES_ARM_ACTIONS] = {
[PROBES_LDRSTRD] = {.checker = arm_check_stack},
[PROBES_STORE_EXTRA] = {.checker = arm_check_stack},
[PROBES_STORE] = {.checker = arm_check_stack},
[PROBES_LDMSTM] = {.checker = arm_check_stack},
};
static enum probes_insn __kprobes arm_check_regs_nouse(probes_opcode_t insn,
struct arch_probes_insn *asi,
const struct decode_header *h)
{
asi->register_usage_flags = 0;
return INSN_GOOD;
}
static enum probes_insn arm_check_regs_normal(probes_opcode_t insn,
struct arch_probes_insn *asi,
const struct decode_header *h)
{
u32 regs = h->type_regs.bits >> DECODE_TYPE_BITS;
int i;
asi->register_usage_flags = 0;
for (i = 0; i < 5; regs >>= 4, insn >>= 4, i++)
if (regs & 0xf)
asi->register_usage_flags |= 1 << (insn & 0xf);
return INSN_GOOD;
}
static enum probes_insn arm_check_regs_ldmstm(probes_opcode_t insn,
struct arch_probes_insn *asi,
const struct decode_header *h)
{
unsigned int reglist = insn & 0xffff;
unsigned int rn = (insn >> 16) & 0xf;
asi->register_usage_flags = reglist | (1 << rn);
return INSN_GOOD;
}
static enum probes_insn arm_check_regs_mov_ip_sp(probes_opcode_t insn,
struct arch_probes_insn *asi,
const struct decode_header *h)
{
/* Instruction is 'mov ip, sp' i.e. 'mov r12, r13' */
asi->register_usage_flags = (1 << 12) | (1<< 13);
return INSN_GOOD;
}
/*
* | Rn |Rt/d| | Rm |
* LDRD (register) cccc 000x x0x0 xxxx xxxx xxxx 1101 xxxx
* STRD (register) cccc 000x x0x0 xxxx xxxx xxxx 1111 xxxx
* | Rn |Rt/d| |imm4L|
* LDRD (immediate) cccc 000x x1x0 xxxx xxxx xxxx 1101 xxxx
* STRD (immediate) cccc 000x x1x0 xxxx xxxx xxxx 1111 xxxx
*
* Such instructions access Rt/d and its next register, so different
* from others, a specific checker is required to handle this extra
* implicit register usage.
*/
static enum probes_insn arm_check_regs_ldrdstrd(probes_opcode_t insn,
struct arch_probes_insn *asi,
const struct decode_header *h)
{
int rdt = (insn >> 12) & 0xf;
arm_check_regs_normal(insn, asi, h);
asi->register_usage_flags |= 1 << (rdt + 1);
return INSN_GOOD;
}
const struct decode_checker arm_regs_checker[NUM_PROBES_ARM_ACTIONS] = {
[PROBES_MRS] = {.checker = arm_check_regs_normal},
[PROBES_SATURATING_ARITHMETIC] = {.checker = arm_check_regs_normal},
[PROBES_MUL1] = {.checker = arm_check_regs_normal},
[PROBES_MUL2] = {.checker = arm_check_regs_normal},
[PROBES_MUL_ADD_LONG] = {.checker = arm_check_regs_normal},
[PROBES_MUL_ADD] = {.checker = arm_check_regs_normal},
[PROBES_LOAD] = {.checker = arm_check_regs_normal},
[PROBES_LOAD_EXTRA] = {.checker = arm_check_regs_normal},
[PROBES_STORE] = {.checker = arm_check_regs_normal},
[PROBES_STORE_EXTRA] = {.checker = arm_check_regs_normal},
[PROBES_DATA_PROCESSING_REG] = {.checker = arm_check_regs_normal},
[PROBES_DATA_PROCESSING_IMM] = {.checker = arm_check_regs_normal},
[PROBES_SEV] = {.checker = arm_check_regs_nouse},
[PROBES_WFE] = {.checker = arm_check_regs_nouse},
[PROBES_SATURATE] = {.checker = arm_check_regs_normal},
[PROBES_REV] = {.checker = arm_check_regs_normal},
[PROBES_MMI] = {.checker = arm_check_regs_normal},
[PROBES_PACK] = {.checker = arm_check_regs_normal},
[PROBES_EXTEND] = {.checker = arm_check_regs_normal},
[PROBES_EXTEND_ADD] = {.checker = arm_check_regs_normal},
[PROBES_BITFIELD] = {.checker = arm_check_regs_normal},
[PROBES_LDMSTM] = {.checker = arm_check_regs_ldmstm},
[PROBES_MOV_IP_SP] = {.checker = arm_check_regs_mov_ip_sp},
[PROBES_LDRSTRD] = {.checker = arm_check_regs_ldrdstrd},
};
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