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arm64: Add helper to decode register from instruction

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Add a helper to extract the register field from a given
instruction.

Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
This commit is contained in:
Suzuki K Poulose 2017-01-09 17:28:29 +00:00 committed by Will Deacon
parent c9ee0f9866
commit 8c2dcbd2c4
2 changed files with 31 additions and 0 deletions
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2
arch/arm64/include/asm/insn.h
View File

@ -332,6 +332,8 @@ bool aarch64_insn_is_branch(u32 insn);
u64 aarch64_insn_decode_immediate(enum aarch64_insn_imm_type type, u32 insn);
u32 aarch64_insn_encode_immediate(enum aarch64_insn_imm_type type,
u32 insn, u64 imm);
u32 aarch64_insn_decode_register(enum aarch64_insn_register_type type,
u32 insn);
u32 aarch64_insn_gen_branch_imm(unsigned long pc, unsigned long addr,
enum aarch64_insn_branch_type type);
u32 aarch64_insn_gen_comp_branch_imm(unsigned long pc, unsigned long addr,

29
arch/arm64/kernel/insn.c
View File

@ -417,6 +417,35 @@ u32 __kprobes aarch64_insn_encode_immediate(enum aarch64_insn_imm_type type,
return insn;
}
u32 aarch64_insn_decode_register(enum aarch64_insn_register_type type,
u32 insn)
{
int shift;
switch (type) {
case AARCH64_INSN_REGTYPE_RT:
case AARCH64_INSN_REGTYPE_RD:
shift = 0;
break;
case AARCH64_INSN_REGTYPE_RN:
shift = 5;
break;
case AARCH64_INSN_REGTYPE_RT2:
case AARCH64_INSN_REGTYPE_RA:
shift = 10;
break;
case AARCH64_INSN_REGTYPE_RM:
shift = 16;
break;
default:
pr_err("%s: unknown register type encoding %d\n", __func__,
type);
return 0;
}
return (insn >> shift) & GENMASK(4, 0);
}
static u32 aarch64_insn_encode_register(enum aarch64_insn_register_type type,
u32 insn,
enum aarch64_insn_register reg)