arch/arm/probes/kprobes/checkers-common.c

   1 /*
   2  * arch/arm/probes/kprobes/checkers-common.c
   3  *
   4  * Copyright (C) 2014 Huawei Inc.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * General Public License for more details.
  14  */
  15
  16 #include <linux/kernel.h>
  17 #include "../decode.h"
  18 #include "../decode-arm.h"
  19 #include "checkers.h"
  20
  21 enum probes_insn checker_stack_use_none(probes_opcode_t insn,
  22                 struct arch_probes_insn *asi,
  23                 const struct decode_header *h)
  24 {
  25         asi->stack_space = 0;
  26         return INSN_GOOD_NO_SLOT;
  27 }
  28
  29 enum probes_insn checker_stack_use_unknown(probes_opcode_t insn,
  30                 struct arch_probes_insn *asi,
  31                 const struct decode_header *h)
  32 {
  33         asi->stack_space = -1;
  34         return INSN_GOOD_NO_SLOT;
  35 }
  36
  37 #ifdef CONFIG_THUMB2_KERNEL
  38 enum probes_insn checker_stack_use_imm_0xx(probes_opcode_t insn,
  39                 struct arch_probes_insn *asi,
  40                 const struct decode_header *h)
  41 {
  42         int imm = insn & 0xff;
  43         asi->stack_space = imm;
  44         return INSN_GOOD_NO_SLOT;
  45 }
  46
  47 /*
  48  * Different from other insn uses imm8, the real addressing offset of
  49  * STRD in T32 encoding should be imm8 * 4. See ARMARM description.
  50  */
  51 enum probes_insn checker_stack_use_t32strd(probes_opcode_t insn,
  52                 struct arch_probes_insn *asi,
  53                 const struct decode_header *h)
  54 {
  55         int imm = insn & 0xff;
  56         asi->stack_space = imm << 2;
  57         return INSN_GOOD_NO_SLOT;
  58 }
  59 #else
  60 enum probes_insn checker_stack_use_imm_x0x(probes_opcode_t insn,
  61                 struct arch_probes_insn *asi,
  62                 const struct decode_header *h)
  63 {
  64         int imm = ((insn & 0xf00) >> 4) + (insn & 0xf);
  65         asi->stack_space = imm;
  66         return INSN_GOOD_NO_SLOT;
  67 }
  68 #endif
  69
  70 enum probes_insn checker_stack_use_imm_xxx(probes_opcode_t insn,
  71                 struct arch_probes_insn *asi,
  72                 const struct decode_header *h)
  73 {
  74         int imm = insn & 0xfff;
  75         asi->stack_space = imm;
  76         return INSN_GOOD_NO_SLOT;
  77 }
  78
  79 enum probes_insn checker_stack_use_stmdx(probes_opcode_t insn,
  80                 struct arch_probes_insn *asi,
  81                 const struct decode_header *h)
  82 {
  83         unsigned int reglist = insn & 0xffff;
  84         int pbit = insn & (1 << 24);
  85         asi->stack_space = (hweight32(reglist) - (!pbit ? 1 : 0)) * 4;
  86
  87         return INSN_GOOD_NO_SLOT;
  88 }
  89
  90 const union decode_action stack_check_actions[] = {
  91         [STACK_USE_NONE] = {.decoder = checker_stack_use_none},
  92         [STACK_USE_UNKNOWN] = {.decoder = checker_stack_use_unknown},
  93 #ifdef CONFIG_THUMB2_KERNEL
  94         [STACK_USE_FIXED_0XX] = {.decoder = checker_stack_use_imm_0xx},
  95         [STACK_USE_T32STRD] = {.decoder = checker_stack_use_t32strd},
  96 #else
  97         [STACK_USE_FIXED_X0X] = {.decoder = checker_stack_use_imm_x0x},
  98 #endif
  99         [STACK_USE_FIXED_XXX] = {.decoder = checker_stack_use_imm_xxx},
 100         [STACK_USE_STMDX] = {.decoder = checker_stack_use_stmdx},
 101 };