Commit b11a64a4 authored by Jiang Liu's avatar Jiang Liu Committed by Catalin Marinas

arm64: introduce basic aarch64 instruction decoding helpers

Introduce basic aarch64 instruction decoding helper
aarch64_get_insn_class() and aarch64_insn_hotpatch_safe().
Reviewed-by: default avatarWill Deacon <will.deacon@arm.com>
Signed-off-by: default avatarJiang Liu <liuj97@gmail.com>
Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
parent 4e5e1eb8
/*
* 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/>.
*/
#ifndef __ASM_INSN_H
#define __ASM_INSN_H
#include <linux/types.h>
/*
* ARM Architecture Reference Manual for ARMv8 Profile-A, Issue A.a
* Section C3.1 "A64 instruction index by encoding":
* AArch64 main encoding table
* Bit position
* 28 27 26 25 Encoding Group
* 0 0 - - Unallocated
* 1 0 0 - Data processing, immediate
* 1 0 1 - Branch, exception generation and system instructions
* - 1 - 0 Loads and stores
* - 1 0 1 Data processing - register
* 0 1 1 1 Data processing - SIMD and floating point
* 1 1 1 1 Data processing - SIMD and floating point
* "-" means "don't care"
*/
enum aarch64_insn_encoding_class {
AARCH64_INSN_CLS_UNKNOWN, /* UNALLOCATED */
AARCH64_INSN_CLS_DP_IMM, /* Data processing - immediate */
AARCH64_INSN_CLS_DP_REG, /* Data processing - register */
AARCH64_INSN_CLS_DP_FPSIMD, /* Data processing - SIMD and FP */
AARCH64_INSN_CLS_LDST, /* Loads and stores */
AARCH64_INSN_CLS_BR_SYS, /* Branch, exception generation and
* system instructions */
};
enum aarch64_insn_hint_op {
AARCH64_INSN_HINT_NOP = 0x0 << 5,
AARCH64_INSN_HINT_YIELD = 0x1 << 5,
AARCH64_INSN_HINT_WFE = 0x2 << 5,
AARCH64_INSN_HINT_WFI = 0x3 << 5,
AARCH64_INSN_HINT_SEV = 0x4 << 5,
AARCH64_INSN_HINT_SEVL = 0x5 << 5,
};
#define __AARCH64_INSN_FUNCS(abbr, mask, val) \
static __always_inline bool aarch64_insn_is_##abbr(u32 code) \
{ return (code & (mask)) == (val); } \
static __always_inline u32 aarch64_insn_get_##abbr##_value(void) \
{ return (val); }
__AARCH64_INSN_FUNCS(b, 0xFC000000, 0x14000000)
__AARCH64_INSN_FUNCS(bl, 0xFC000000, 0x94000000)
__AARCH64_INSN_FUNCS(svc, 0xFFE0001F, 0xD4000001)
__AARCH64_INSN_FUNCS(hvc, 0xFFE0001F, 0xD4000002)
__AARCH64_INSN_FUNCS(smc, 0xFFE0001F, 0xD4000003)
__AARCH64_INSN_FUNCS(brk, 0xFFE0001F, 0xD4200000)
__AARCH64_INSN_FUNCS(hint, 0xFFFFF01F, 0xD503201F)
#undef __AARCH64_INSN_FUNCS
bool aarch64_insn_is_nop(u32 insn);
enum aarch64_insn_encoding_class aarch64_get_insn_class(u32 insn);
bool aarch64_insn_hotpatch_safe(u32 old_insn, u32 new_insn);
#endif /* __ASM_INSN_H */
......@@ -9,7 +9,7 @@ AFLAGS_head.o := -DTEXT_OFFSET=$(TEXT_OFFSET)
arm64-obj-y := cputable.o debug-monitors.o entry.o irq.o fpsimd.o \
entry-fpsimd.o process.o ptrace.o setup.o signal.o \
sys.o stacktrace.o time.o traps.o io.o vdso.o \
hyp-stub.o psci.o cpu_ops.o
hyp-stub.o psci.o cpu_ops.o insn.o
arm64-obj-$(CONFIG_COMPAT) += sys32.o kuser32.o signal32.o \
sys_compat.o
......
/*
* 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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