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

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * arch/arm/probes/kprobes/checkers-common.c
   4  *
   5  * Copyright (C) 2014 Huawei Inc.
   6  */
   7
   8 #include <linux/kernel.h>
   9 #include "../decode.h"
  10 #include "../decode-arm.h"
  11 #include "checkers.h"
  12
  13 enum probes_insn checker_stack_use_none(probes_opcode_t insn,
  14                 struct arch_probes_insn *asi,
  15                 const struct decode_header *h)
  16 {
  17         asi->stack_space = 0;
  18         return INSN_GOOD_NO_SLOT;
  19 }
  20
  21 enum probes_insn checker_stack_use_unknown(probes_opcode_t insn,
  22                 struct arch_probes_insn *asi,
  23                 const struct decode_header *h)
  24 {
  25         asi->stack_space = -1;
  26         return INSN_GOOD_NO_SLOT;
  27 }
  28
  29 #ifdef CONFIG_THUMB2_KERNEL
  30 enum probes_insn checker_stack_use_imm_0xx(probes_opcode_t insn,
  31                 struct arch_probes_insn *asi,
  32                 const struct decode_header *h)
  33 {
  34         int imm = insn & 0xff;
  35         asi->stack_space = imm;
  36         return INSN_GOOD_NO_SLOT;
  37 }
  38
  39 /*
  40  * Different from other insn uses imm8, the real addressing offset of
  41  * STRD in T32 encoding should be imm8 * 4. See ARMARM description.
  42  */
  43 enum probes_insn checker_stack_use_t32strd(probes_opcode_t insn,
  44                 struct arch_probes_insn *asi,
  45                 const struct decode_header *h)
  46 {
  47         int imm = insn & 0xff;
  48         asi->stack_space = imm << 2;
  49         return INSN_GOOD_NO_SLOT;
  50 }
  51 #else
  52 enum probes_insn checker_stack_use_imm_x0x(probes_opcode_t insn,
  53                 struct arch_probes_insn *asi,
  54                 const struct decode_header *h)
  55 {
  56         int imm = ((insn & 0xf00) >> 4) + (insn & 0xf);
  57         asi->stack_space = imm;
  58         return INSN_GOOD_NO_SLOT;
  59 }
  60 #endif
  61
  62 enum probes_insn checker_stack_use_imm_xxx(probes_opcode_t insn,
  63                 struct arch_probes_insn *asi,
  64                 const struct decode_header *h)
  65 {
  66         int imm = insn & 0xfff;
  67         asi->stack_space = imm;
  68         return INSN_GOOD_NO_SLOT;
  69 }
  70
  71 enum probes_insn checker_stack_use_stmdx(probes_opcode_t insn,
  72                 struct arch_probes_insn *asi,
  73                 const struct decode_header *h)
  74 {
  75         unsigned int reglist = insn & 0xffff;
  76         int pbit = insn & (1 << 24);
  77         asi->stack_space = (hweight32(reglist) - (!pbit ? 1 : 0)) * 4;
  78
  79         return INSN_GOOD_NO_SLOT;
  80 }
  81
  82 const union decode_action stack_check_actions[] = {
  83         [STACK_USE_NONE] = {.decoder = checker_stack_use_none},
  84         [STACK_USE_UNKNOWN] = {.decoder = checker_stack_use_unknown},
  85 #ifdef CONFIG_THUMB2_KERNEL
  86         [STACK_USE_FIXED_0XX] = {.decoder = checker_stack_use_imm_0xx},
  87         [STACK_USE_T32STRD] = {.decoder = checker_stack_use_t32strd},
  88 #else
  89         [STACK_USE_FIXED_X0X] = {.decoder = checker_stack_use_imm_x0x},
  90 #endif
  91         [STACK_USE_FIXED_XXX] = {.decoder = checker_stack_use_imm_xxx},
  92         [STACK_USE_STMDX] = {.decoder = checker_stack_use_stmdx},
  93 };