Introduce basic aarch64 instruction decoding helper aarch64_get_insn_class() and aarch64_insn_hotpatch_safe().
Reviewed-by: Will Deacon <will.dea...@arm.com> Signed-off-by: Jiang Liu <liu...@gmail.com> --- arch/arm64/include/asm/insn.h | 77 ++++++++++++++++++++++++++++++++++++ arch/arm64/kernel/Makefile | 2 +- arch/arm64/kernel/insn.c | 91 +++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 169 insertions(+), 1 deletion(-) create mode 100644 arch/arm64/include/asm/insn.h create mode 100644 arch/arm64/kernel/insn.c diff --git a/arch/arm64/include/asm/insn.h b/arch/arm64/include/asm/insn.h new file mode 100644 index 0000000..1bdc44c --- /dev/null +++ b/arch/arm64/include/asm/insn.h @@ -0,0 +1,77 @@ +/* + * Copyright (C) 2013 Huawei Ltd. + * Author: Jiang Liu <liu...@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 */ diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile index 5ba2fd4..cd95a25 100644 --- a/arch/arm64/kernel/Makefile +++ b/arch/arm64/kernel/Makefile @@ -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 diff --git a/arch/arm64/kernel/insn.c b/arch/arm64/kernel/insn.c new file mode 100644 index 0000000..56a2498 --- /dev/null +++ b/arch/arm64/kernel/insn.c @@ -0,0 +1,91 @@ +/* + * Copyright (C) 2013 Huawei Ltd. + * Author: Jiang Liu <liu...@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); +} -- 1.8.1.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
