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SubjectRe: [PATCH v3 3/7] arm64: move encode_insn_immediate() from module.c to insn.c
On 10/16/2013 07:22 PM, Will Deacon wrote:
> On Wed, Oct 16, 2013 at 04:18:08AM +0100, Jiang Liu wrote:
>> From: Jiang Liu <jiang.liu@huawei.com>
>>
>> Function encode_insn_immediate() will be used by other instruction
>> manipulate related functions, so move it into insn.c and rename it
>> as aarch64_insn_encode_immediate().
>>
>> Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
>> Cc: Jiang Liu <liuj97@gmail.com>
>> ---
>> arch/arm64/include/asm/insn.h | 14 ++++
>> arch/arm64/kernel/insn.c | 77 +++++++++++++++++++++
>> arch/arm64/kernel/module.c | 151 +++++++++---------------------------------
>> 3 files changed, 123 insertions(+), 119 deletions(-)
>>
>> diff --git a/arch/arm64/include/asm/insn.h b/arch/arm64/include/asm/insn.h
>> index 2dfcdb4..8dc0a91 100644
>> --- a/arch/arm64/include/asm/insn.h
>> +++ b/arch/arm64/include/asm/insn.h
>> @@ -28,6 +28,18 @@ enum aarch64_insn_class {
>> * system instructions */
>> };
>>
>> +enum aarch64_insn_imm_type {
>> + AARCH64_INSN_IMM_MOVNZ,
>> + AARCH64_INSN_IMM_MOVK,
>> + AARCH64_INSN_IMM_ADR,
>> + AARCH64_INSN_IMM_26,
>> + AARCH64_INSN_IMM_19,
>> + AARCH64_INSN_IMM_16,
>> + AARCH64_INSN_IMM_14,
>> + AARCH64_INSN_IMM_12,
>> + AARCH64_INSN_IMM_9,
>> +};
>> +
>> #define __AARCH64_INSN_FUNCS(abbr, mask, val) \
>> static __always_inline bool aarch64_insn_is_##abbr(u32 code) \
>> { return (code & (mask)) == (val); } \
>> @@ -47,6 +59,8 @@ __AARCH64_INSN_FUNCS(nop, 0xFFFFFFFF, 0xD503201F)
>> #undef __AARCH64_INSN_FUNCS
>>
>> enum aarch64_insn_class aarch64_get_insn_class(u32 insn);
>> +u32 aarch64_insn_encode_immediate(enum aarch64_insn_imm_type type,
>> + u32 insn, u64 imm);
>> u32 aarch64_insn_read(void *addr);
>> void aarch64_insn_write(void *addr, u32 insn);
>> bool aarch64_insn_hotpatch_safe(u32 old_insn, u32 new_insn);
>> diff --git a/arch/arm64/kernel/insn.c b/arch/arm64/kernel/insn.c
>> index ad4185f..90cc312 100644
>> --- a/arch/arm64/kernel/insn.c
>> +++ b/arch/arm64/kernel/insn.c
>> @@ -179,3 +179,80 @@ int __kprobes aarch64_insn_patch_text(void *addrs[], u32 insns[], int cnt)
>> else
>> return aarch64_insn_patch_text_sync(addrs, insns, cnt);
>> }
>> +
>> +u32 aarch64_insn_encode_immediate(enum aarch64_insn_imm_type type,
>> + u32 insn, u64 imm)
>> +{
>> + u32 immlo, immhi, lomask, himask, mask;
>> + int shift;
>> +
>> + switch (type) {
>> + case AARCH64_INSN_IMM_MOVNZ:
>> + /*
>> + * For signed MOVW relocations, we have to manipulate the
>> + * instruction encoding depending on whether or not the
>> + * immediate is less than zero.
>> + */
>> + insn &= ~(3 << 29);
>> + if ((s64)imm >= 0) {
>> + /* >=0: Set the instruction to MOVZ (opcode 10b). */
>> + insn |= 2 << 29;
>> + } else {
>> + /*
>> + * <0: Set the instruction to MOVN (opcode 00b).
>> + * Since we've masked the opcode already, we
>> + * don't need to do anything other than
>> + * inverting the new immediate field.
>> + */
>> + imm = ~imm;
>> + }
>
> I'm really not comfortable with this. This code is performing static
> relocations and re-encoding instructions as required by the AArch64 ELF
> spec. That's not really what you'd expect from a generic instruction
> encoder!
Thanks for reminder, will move above code back into module.c.
Thanks!
Gerry

>
> Will
>



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