Re: [PATCH v4 15/19] arm64; insn: Add encoder for the EXTR instruction

From: Christoffer Dall <christoffer.dall@linaro.org>
To: Marc Zyngier <marc.zyngier@arm.com>
Cc: linux-arm-kernel@lists.infradead.org, kvm@vger.kernel.org,
	kvmarm@lists.cs.columbia.edu, Mark Rutland <mark.rutland@arm.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will.deacon@arm.com>,
	James Morse <james.morse@arm.com>,
	Steve Capper <steve.capper@arm.com>,
	Peter Maydell <peter.maydell@linaro.org>
Subject: Re: [PATCH v4 15/19] arm64; insn: Add encoder for the EXTR instruction
Date: Thu, 18 Jan 2018 21:27:58 +0100	[thread overview]
Message-ID: <20180118202758.GC21802@cbox> (raw)
In-Reply-To: <20180104184334.16571-16-marc.zyngier@arm.com>

On Thu, Jan 04, 2018 at 06:43:30PM +0000, Marc Zyngier wrote:
> Add an encoder for the EXTR instruction, which also implements the ROR
> variant (where Rn == Rm).
> 
> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
> ---
>  arch/arm64/include/asm/insn.h |  6 ++++++
>  arch/arm64/kernel/insn.c      | 32 ++++++++++++++++++++++++++++++++
>  2 files changed, 38 insertions(+)
> 
> diff --git a/arch/arm64/include/asm/insn.h b/arch/arm64/include/asm/insn.h
> index 815b35bc53ed..f62c56b1793f 100644
> --- a/arch/arm64/include/asm/insn.h
> +++ b/arch/arm64/include/asm/insn.h
> @@ -319,6 +319,7 @@ __AARCH64_INSN_FUNCS(and_imm,	0x7F800000, 0x12000000)
>  __AARCH64_INSN_FUNCS(orr_imm,	0x7F800000, 0x32000000)
>  __AARCH64_INSN_FUNCS(eor_imm,	0x7F800000, 0x52000000)
>  __AARCH64_INSN_FUNCS(ands_imm,	0x7F800000, 0x72000000)
> +__AARCH64_INSN_FUNCS(extr,	0x7FA00000, 0x13800000)
>  __AARCH64_INSN_FUNCS(b,		0xFC000000, 0x14000000)
>  __AARCH64_INSN_FUNCS(bl,	0xFC000000, 0x94000000)
>  __AARCH64_INSN_FUNCS(cbz,	0x7F000000, 0x34000000)
> @@ -433,6 +434,11 @@ u32 aarch64_insn_gen_logical_immediate(enum aarch64_insn_logic_type type,
>  				       enum aarch64_insn_register Rn,
>  				       enum aarch64_insn_register Rd,
>  				       u64 imm);
> +u32 aarch64_insn_gen_extr(enum aarch64_insn_variant variant,
> +			  enum aarch64_insn_register Rm,
> +			  enum aarch64_insn_register Rn,
> +			  enum aarch64_insn_register Rd,
> +			  u8 lsb);
>  u32 aarch64_insn_gen_prefetch(enum aarch64_insn_register base,
>  			      enum aarch64_insn_prfm_type type,
>  			      enum aarch64_insn_prfm_target target,
> diff --git a/arch/arm64/kernel/insn.c b/arch/arm64/kernel/insn.c
> index 72cb1721c63f..59669d7d4383 100644
> --- a/arch/arm64/kernel/insn.c
> +++ b/arch/arm64/kernel/insn.c
> @@ -1621,3 +1621,35 @@ u32 aarch64_insn_gen_logical_immediate(enum aarch64_insn_logic_type type,
>  	insn = aarch64_insn_encode_register(AARCH64_INSN_REGTYPE_RN, insn, Rn);
>  	return aarch64_encode_immediate(imm, variant, insn);
>  }
> +
> +u32 aarch64_insn_gen_extr(enum aarch64_insn_variant variant,
> +			  enum aarch64_insn_register Rm,
> +			  enum aarch64_insn_register Rn,
> +			  enum aarch64_insn_register Rd,
> +			  u8 lsb)
> +{
> +	u32 insn;
> +
> +	insn = aarch64_insn_get_extr_value();
> +
> +	switch (variant) {
> +	case AARCH64_INSN_VARIANT_32BIT:
> +		if (lsb > 31)
> +			return AARCH64_BREAK_FAULT;
> +		break;
> +	case AARCH64_INSN_VARIANT_64BIT:
> +		if (lsb > 63)
> +			return AARCH64_BREAK_FAULT;
> +		insn |= AARCH64_INSN_SF_BIT;
> +		insn = aarch64_insn_encode_immediate(AARCH64_INSN_IMM_N, insn, 1);
> +		break;
> +	default:
> +		pr_err("%s: unknown variant encoding %d\n", __func__, variant);
> +		return AARCH64_BREAK_FAULT;
> +	}
> +
> +	insn = aarch64_insn_encode_immediate(AARCH64_INSN_IMM_S, insn, lsb);
> +	insn = aarch64_insn_encode_register(AARCH64_INSN_REGTYPE_RD, insn, Rd);
> +	insn = aarch64_insn_encode_register(AARCH64_INSN_REGTYPE_RN, insn, Rn);
> +	return aarch64_insn_encode_register(AARCH64_INSN_REGTYPE_RM, insn, Rm);
> +}
> -- 
> 2.14.2
> 

Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>