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/*
* Copyright (C) 2013 Huawei Ltd.
* Author: Jiang Liu <liuj97@gmail.com>
*
* 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.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <linux/compiler.h>
#include <linux/kernel.h>
#include <asm/insn.h>
static int aarch64_insn_encoding_class[] = {
AARCH64_INSN_CLS_UNKNOWN,
AARCH64_INSN_CLS_UNKNOWN,
AARCH64_INSN_CLS_UNKNOWN,
AARCH64_INSN_CLS_UNKNOWN,
AARCH64_INSN_CLS_LDST,
AARCH64_INSN_CLS_DP_REG,
AARCH64_INSN_CLS_LDST,
AARCH64_INSN_CLS_DP_FPSIMD,
AARCH64_INSN_CLS_DP_IMM,
AARCH64_INSN_CLS_DP_IMM,
AARCH64_INSN_CLS_BR_SYS,
AARCH64_INSN_CLS_BR_SYS,
AARCH64_INSN_CLS_LDST,
AARCH64_INSN_CLS_DP_REG,
AARCH64_INSN_CLS_LDST,
AARCH64_INSN_CLS_DP_FPSIMD,
};
enum aarch64_insn_encoding_class __kprobes aarch64_get_insn_class(u32 insn)
{
return aarch64_insn_encoding_class[(insn >> 25) & 0xf];
}
/* NOP is an alias of HINT */
bool __kprobes aarch64_insn_is_nop(u32 insn)
{
if (!aarch64_insn_is_hint(insn))
return false;
switch (insn & 0xFE0) {
case AARCH64_INSN_HINT_YIELD:
case AARCH64_INSN_HINT_WFE:
case AARCH64_INSN_HINT_WFI:
case AARCH64_INSN_HINT_SEV:
case AARCH64_INSN_HINT_SEVL:
return false;
default:
return true;
}
}
static bool __kprobes __aarch64_insn_hotpatch_safe(u32 insn)
{
if (aarch64_get_insn_class(insn) != AARCH64_INSN_CLS_BR_SYS)
return false;
return aarch64_insn_is_b(insn) ||
aarch64_insn_is_bl(insn) ||
aarch64_insn_is_svc(insn) ||
aarch64_insn_is_hvc(insn) ||
aarch64_insn_is_smc(insn) ||
aarch64_insn_is_brk(insn) ||
aarch64_insn_is_nop(insn);
}
/*
* ARM Architecture Reference Manual for ARMv8 Profile-A, Issue A.a
* Section B2.6.5 "Concurrent modification and execution of instructions":
* Concurrent modification and execution of instructions can lead to the
* resulting instruction performing any behavior that can be achieved by
* executing any sequence of instructions that can be executed from the
* same Exception level, except where the instruction before modification
* and the instruction after modification is a B, BL, NOP, BKPT, SVC, HVC,
* or SMC instruction.
*/
bool __kprobes aarch64_insn_hotpatch_safe(u32 old_insn, u32 new_insn)
{
return __aarch64_insn_hotpatch_safe(old_insn) &&
__aarch64_insn_hotpatch_safe(new_insn);
}
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