92 lines
2.7 KiB
C
92 lines
2.7 KiB
C
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/*
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* Copyright (C) 2013 Huawei Ltd.
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* Author: Jiang Liu <liuj97@gmail.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <linux/compiler.h>
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#include <linux/kernel.h>
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#include <asm/insn.h>
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static int aarch64_insn_encoding_class[] = {
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AARCH64_INSN_CLS_UNKNOWN,
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AARCH64_INSN_CLS_UNKNOWN,
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AARCH64_INSN_CLS_UNKNOWN,
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AARCH64_INSN_CLS_UNKNOWN,
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AARCH64_INSN_CLS_LDST,
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AARCH64_INSN_CLS_DP_REG,
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AARCH64_INSN_CLS_LDST,
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AARCH64_INSN_CLS_DP_FPSIMD,
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AARCH64_INSN_CLS_DP_IMM,
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AARCH64_INSN_CLS_DP_IMM,
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AARCH64_INSN_CLS_BR_SYS,
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AARCH64_INSN_CLS_BR_SYS,
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AARCH64_INSN_CLS_LDST,
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AARCH64_INSN_CLS_DP_REG,
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AARCH64_INSN_CLS_LDST,
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AARCH64_INSN_CLS_DP_FPSIMD,
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};
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enum aarch64_insn_encoding_class __kprobes aarch64_get_insn_class(u32 insn)
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{
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return aarch64_insn_encoding_class[(insn >> 25) & 0xf];
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}
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/* NOP is an alias of HINT */
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bool __kprobes aarch64_insn_is_nop(u32 insn)
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{
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if (!aarch64_insn_is_hint(insn))
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return false;
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switch (insn & 0xFE0) {
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case AARCH64_INSN_HINT_YIELD:
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case AARCH64_INSN_HINT_WFE:
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case AARCH64_INSN_HINT_WFI:
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case AARCH64_INSN_HINT_SEV:
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case AARCH64_INSN_HINT_SEVL:
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return false;
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default:
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return true;
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}
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}
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static bool __kprobes __aarch64_insn_hotpatch_safe(u32 insn)
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{
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if (aarch64_get_insn_class(insn) != AARCH64_INSN_CLS_BR_SYS)
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return false;
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return aarch64_insn_is_b(insn) ||
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aarch64_insn_is_bl(insn) ||
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aarch64_insn_is_svc(insn) ||
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aarch64_insn_is_hvc(insn) ||
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aarch64_insn_is_smc(insn) ||
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aarch64_insn_is_brk(insn) ||
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aarch64_insn_is_nop(insn);
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}
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/*
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* ARM Architecture Reference Manual for ARMv8 Profile-A, Issue A.a
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* Section B2.6.5 "Concurrent modification and execution of instructions":
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* Concurrent modification and execution of instructions can lead to the
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* resulting instruction performing any behavior that can be achieved by
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* executing any sequence of instructions that can be executed from the
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* same Exception level, except where the instruction before modification
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* and the instruction after modification is a B, BL, NOP, BKPT, SVC, HVC,
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* or SMC instruction.
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*/
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bool __kprobes aarch64_insn_hotpatch_safe(u32 old_insn, u32 new_insn)
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{
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return __aarch64_insn_hotpatch_safe(old_insn) &&
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__aarch64_insn_hotpatch_safe(new_insn);
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}
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