From mboxrd@z Thu Jan  1 00:00:00 1970
From: dave.long@linaro.org (David Long)
Date: Wed, 1 Jun 2016 01:15:41 -0400
Subject: [PATCH v12 05/10] arm64: Kprobes with single stepping support
In-Reply-To: <20160517091009.GA5082@sha-win-210.asiapac.arm.com>
References: <1461783185-9056-1-git-send-email-dave.long@linaro.org>
 <1461783185-9056-6-git-send-email-dave.long@linaro.org>
 <20160517091009.GA5082@sha-win-210.asiapac.arm.com>
Message-ID: <574E6F7D.1040902@linaro.org>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

On 05/17/2016 05:10 AM, Huang Shijie wrote:
> On Wed, Apr 27, 2016 at 02:53:00PM -0400, David Long wrote:
>> From: Sandeepa Prabhu <sandeepa.s.prabhu@gmail.com>
>> +
>> +static bool __kprobes aarch64_insn_is_steppable(u32 insn)
>
> Could we add more comment for this function? In the comment, we can tell
> that which type of instructions are steppable, which are not.
>
>> +{
>> +	if (aarch64_get_insn_class(insn) == AARCH64_INSN_CLS_BR_SYS) {
>> +		if (aarch64_insn_is_branch(insn) ||
>> +		    aarch64_insn_is_msr_imm(insn) ||
>> +		    aarch64_insn_is_msr_reg(insn) ||
>> +		    aarch64_insn_is_exception(insn))
>> +			return false;
>> +
>> +		if (aarch64_insn_is_mrs(insn))
>> +			return aarch64_insn_extract_system_reg(insn)
>> +			     != AARCH64_INSN_SPCLREG_DAIF;
>> +
>> +		if (aarch64_insn_is_hint(insn))
>> +			return aarch64_insn_is_nop(insn);
>> +
>> +		return true;
>> +	}
>> +
>> +	if (aarch64_insn_uses_literal(insn) ||
>> +	    aarch64_insn_is_exclusive(insn))
>> +		return false;
>> +
>> +	return true;
>
> Thanks
> Huang Shijie
>

I did add a comment to this for the next version of the patch.

-dl

From mboxrd@z Thu Jan  1 00:00:00 1970
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Subject: Re: [PATCH v12 05/10] arm64: Kprobes with single stepping support
To: Huang Shijie <shijie.huang@arm.com>
References: <1461783185-9056-1-git-send-email-dave.long@linaro.org>
 <1461783185-9056-6-git-send-email-dave.long@linaro.org>
 <20160517091009.GA5082@sha-win-210.asiapac.arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will.deacon@arm.com>,
        Sandeepa Prabhu <sandeepa.s.prabhu@gmail.com>,
        William Cohen <wcohen@redhat.com>, Pratyush Anand <panand@redhat.com>,
        Steve Capper <steve.capper@linaro.org>,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        Marc Zyngier <marc.zyngier@arm.com>,
        Mark Rutland <mark.rutland@arm.com>, Petr Mladek <pmladek@suse.com>,
        Viresh Kumar <viresh.kumar@linaro.org>,
        John Blackwood <john.blackwood@ccur.com>, Feng Kan <fkan@apm.com>,
        Zi Shen Lim <zlim.lnx@gmail.com>, Dave P Martin <Dave.Martin@arm.com>,
        Yang Shi <yang.shi@linaro.org>,
        Vladimir Murzin <Vladimir.Murzin@arm.com>,
        Kees Cook <keescook@chromium.org>,
        "Suzuki K. Poulose" <suzuki.poulose@arm.com>,
        Mark Brown <broonie@kernel.org>,
        =?UTF-8?Q?Alex_Benn=c3=a9e?= <alex.bennee@linaro.org>,
        Ard Biesheuvel <ard.biesheuvel@linaro.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Mark Salyzyn <salyzyn@android.com>, James Morse <james.morse@arm.com>,
        Christoffer Dall <christoffer.dall@linaro.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Robin Murphy <Robin.Murphy@arm.com>,
        Jens Wiklander <jens.wiklander@linaro.org>,
        Balamurugan Shanmugam <bshanmugam@apm.com>, nd@arm.com
From: David Long <dave.long@linaro.org>
Message-ID: <574E6F7D.1040902@linaro.org>
Date: Wed, 1 Jun 2016 01:15:41 -0400
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On 05/17/2016 05:10 AM, Huang Shijie wrote:
> On Wed, Apr 27, 2016 at 02:53:00PM -0400, David Long wrote:
>> From: Sandeepa Prabhu <sandeepa.s.prabhu@gmail.com>
>> +
>> +static bool __kprobes aarch64_insn_is_steppable(u32 insn)
>
> Could we add more comment for this function? In the comment, we can tell
> that which type of instructions are steppable, which are not.
>
>> +{
>> +	if (aarch64_get_insn_class(insn) == AARCH64_INSN_CLS_BR_SYS) {
>> +		if (aarch64_insn_is_branch(insn) ||
>> +		    aarch64_insn_is_msr_imm(insn) ||
>> +		    aarch64_insn_is_msr_reg(insn) ||
>> +		    aarch64_insn_is_exception(insn))
>> +			return false;
>> +
>> +		if (aarch64_insn_is_mrs(insn))
>> +			return aarch64_insn_extract_system_reg(insn)
>> +			     != AARCH64_INSN_SPCLREG_DAIF;
>> +
>> +		if (aarch64_insn_is_hint(insn))
>> +			return aarch64_insn_is_nop(insn);
>> +
>> +		return true;
>> +	}
>> +
>> +	if (aarch64_insn_uses_literal(insn) ||
>> +	    aarch64_insn_is_exclusive(insn))
>> +		return false;
>> +
>> +	return true;
>
> Thanks
> Huang Shijie
>

I did add a comment to this for the next version of the patch.

-dl