cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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checkers-thumb.c (3514B)

      1// SPDX-License-Identifier: GPL-2.0-only
      2/*
      3 * arch/arm/probes/kprobes/checkers-thumb.c
      4 *
      5 * Copyright (C) 2014 Huawei Inc.
      6 */
      7
      8#include <linux/kernel.h>
      9#include "../decode.h"
     10#include "../decode-thumb.h"
     11#include "checkers.h"
     12
     13static enum probes_insn __kprobes t32_check_stack(probes_opcode_t insn,
     14		struct arch_probes_insn *asi,
     15		const struct decode_header *h)
     16{
     17	/*
     18	 * PROBES_T32_LDMSTM, PROBES_T32_LDRDSTRD and PROBES_T32_LDRSTR
     19	 * may get here. Simply mark all normal insns as STACK_USE_NONE.
     20	 */
     21	static const union decode_item table[] = {
     22
     23		/*
     24		 * First, filter out all ldr insns to make our life easier.
     25		 * Following load insns may come here:
     26		 * LDM, LDRD, LDR.
     27		 * In T32 encoding, bit 20 is enough for distinguishing
     28		 * load and store. All load insns have this bit set, when
     29		 * all store insns have this bit clear.
     30		 */
     31		DECODE_CUSTOM	(0x00100000, 0x00100000, STACK_USE_NONE),
     32
     33		/*
     34		 * Mark all 'STR{,B,H}, Rt, [Rn, Rm]' as STACK_USE_UNKNOWN
     35		 * if Rn or Rm is SP. T32 doesn't encode STRD.
     36		 */
     37		/*                                 xx | Rn | Rt |         | Rm |*/
     38		/* STR (register)	1111 1000 0100 xxxx xxxx 0000 00xx xxxx */
     39		/* STRB (register)	1111 1000 0000 xxxx xxxx 0000 00xx xxxx */
     40		/* STRH (register)	1111 1000 0010 xxxx xxxx 0000 00xx xxxx */
     41		/* INVALID INSN		1111 1000 0110 xxxx xxxx 0000 00xx xxxx */
     42		/* By Introducing INVALID INSN, bit 21 and 22 can be ignored. */
     43		DECODE_OR	(0xff9f0fc0, 0xf80d0000),
     44		DECODE_CUSTOM	(0xff900fcf, 0xf800000d, STACK_USE_UNKNOWN),
     45
     46
     47		/*                                 xx | Rn | Rt | PUW|   imm8  |*/
     48		/* STR (imm 8)		1111 1000 0100 1101 xxxx 110x xxxx xxxx */
     49		/* STRB (imm 8)		1111 1000 0000 1101 xxxx 110x xxxx xxxx */
     50		/* STRH (imm 8)		1111 1000 0010 1101 xxxx 110x xxxx xxxx */
     51		/* INVALID INSN		1111 1000 0110 1101 xxxx 110x xxxx xxxx */
     52		/* Only consider U == 0 and P == 1: strx rx, [sp, #-<imm>] */
     53		DECODE_CUSTOM	(0xff9f0e00, 0xf80d0c00, STACK_USE_FIXED_0XX),
     54
     55		/* For STR{,B,H} (imm 12), offset is always positive, so ignore them. */
     56
     57		/*                              P U W | Rn | Rt | Rt2|   imm8  |*/
     58		/* STRD (immediate)	1110 1001 01x0 1101 xxxx xxxx xxxx xxxx */
     59		/*
     60		 * Only consider U == 0 and P == 1.
     61		 * Also note that STRD in T32 encoding is special:
     62		 * imm = ZeroExtend(imm8:'00', 32)
     63		 */
     64		DECODE_CUSTOM	(0xffdf0000, 0xe94d0000, STACK_USE_T32STRD),
     65
     66		/*                                    | Rn | */
     67		/* STMDB		1110 1001 00x0 1101 xxxx xxxx xxxx xxxx */
     68		DECODE_CUSTOM	(0xffdf0000, 0xe90d0000, STACK_USE_STMDX),
     69
     70		/* fall through */
     71		DECODE_CUSTOM	(0, 0, STACK_USE_NONE),
     72		DECODE_END
     73	};
     74
     75	return probes_decode_insn(insn, asi, table, false, false, stack_check_actions, NULL);
     76}
     77
     78const struct decode_checker t32_stack_checker[NUM_PROBES_T32_ACTIONS] = {
     79	[PROBES_T32_LDMSTM] = {.checker = t32_check_stack},
     80	[PROBES_T32_LDRDSTRD] = {.checker = t32_check_stack},
     81	[PROBES_T32_LDRSTR] = {.checker = t32_check_stack},
     82};
     83
     84/*
     85 * See following comments. This insn must be 'push'.
     86 */
     87static enum probes_insn __kprobes t16_check_stack(probes_opcode_t insn,
     88		struct arch_probes_insn *asi,
     89		const struct decode_header *h)
     90{
     91	unsigned int reglist = insn & 0x1ff;
     92	asi->stack_space = hweight32(reglist) * 4;
     93	return INSN_GOOD;
     94}
     95
     96/*
     97 * T16 encoding is simple: only the 'push' insn can need extra stack space.
     98 * Other insns, like str, can only use r0-r7 as Rn.
     99 */
    100const struct decode_checker t16_stack_checker[NUM_PROBES_T16_ACTIONS] = {
    101	[PROBES_T16_PUSH] = {.checker = t16_check_stack},
    102};