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authorAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-08-05 17:04:01 -0300
committerAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-08-05 17:04:01 -0300
commit57f0f512b273f60d52568b8c6b77e17f5636edc0 (patch)
tree5e910f0e82173f4ef4f51111366a3f1299037a7b /arch/arm/probes/kprobes/checkers-thumb.c
Initial import
Diffstat (limited to 'arch/arm/probes/kprobes/checkers-thumb.c')
-rw-r--r--arch/arm/probes/kprobes/checkers-thumb.c110
1 files changed, 110 insertions, 0 deletions
diff --git a/arch/arm/probes/kprobes/checkers-thumb.c b/arch/arm/probes/kprobes/checkers-thumb.c
new file mode 100644
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+++ b/arch/arm/probes/kprobes/checkers-thumb.c
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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},
+};