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From: David Long <dave.long@linaro.org>
To: Marc Zyngier <marc.zyngier@arm.com>, Pratyush Anand <panand@redhat.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>,
	"Steve Capper" <steve.capper@linaro.org>,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org,
	"Dave P Martin" <Dave.Martin@arm.com>,
	"Mark Rutland" <mark.rutland@arm.com>,
	"Robin Murphy" <Robin.Murphy@arm.com>,
	"Ard Biesheuvel" <ard.biesheuvel@linaro.org>,
	"Jens Wiklander" <jens.wiklander@linaro.org>,
	"Christoffer Dall" <christoffer.dall@linaro.org>,
	"Alex Bennée" <alex.bennee@linaro.org>,
	"Yang Shi" <yang.shi@linaro.org>,
	"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
	"Viresh Kumar" <viresh.kumar@linaro.org>,
	"Suzuki K. Poulose" <suzuki.poulose@arm.com>,
	"Kees Cook" <keescook@chromium.org>,
	"Zi Shen Lim" <zlim.lnx@gmail.com>,
	"John Blackwood" <john.blackwood@ccur.com>,
	"Feng Kan" <fkan@apm.com>,
	"Balamurugan Shanmugam" <bshanmugam@apm.com>,
	"James Morse" <james.morse@arm.com>,
	"Vladimir Murzin" <Vladimir.Murzin@arm.com>,
	"Mark Salyzyn" <salyzyn@android.com>,
	"Petr Mladek" <pmladek@suse.com>,
	"Andrew Morton" <akpm@linux-foundation.org>,
	"Mark Brown" <broonie@kernel.org>
Subject: Re: [PATCH v11 4/9] arm64: add conditional instruction simulation support
Date: Mon, 21 Mar 2016 04:35:13 -0400	[thread overview]
Message-ID: <56EFB241.80909@linaro.org> (raw)
In-Reply-To: <20160314073803.22c90d69@arm.com>

On 03/14/2016 03:38 AM, Marc Zyngier wrote:
> On Mon, 14 Mar 2016 09:34:55 +0530
> Pratyush Anand <panand@redhat.com> wrote:
>
> Hi Pratyush,
>
>> On 13/03/2016:12:09:03 PM, Marc Zyngier wrote:
>>> On Wed,  9 Mar 2016 00:32:18 -0500
>>> David Long <dave.long@linaro.org> wrote:
>>>
>>>> +pstate_check_t * const opcode_condition_checks[16] = {
>>>> +	__check_eq, __check_ne, __check_cs, __check_cc,
>>>> +	__check_mi, __check_pl, __check_vs, __check_vc,
>>>> +	__check_hi, __check_ls, __check_ge, __check_lt,
>>>> +	__check_gt, __check_le, __check_al, __check_al
>>>
>>> The very last entry seems wrong, or is at least the opposite of what
>>> the current code has. It should be something called __check_nv(), and
>>> always return false (condition code NEVER).
>>
>> May be __check_nv() name is more appropriate as per definition, but shouldn't it
>> still return true, because TRM says:
>> "The condition code NV exists only to provide a valid disassembly of the 0b1111
>> encoding, otherwise its behavior is identical to AL"
>
> Indeed, I missed that. But this interpretation is for the A64
> instruction set, and this array is also used by the new
> arm32_check_condition. The condition code table for A32 seems to
> completely ignore the 0b1111 code (there is simply no entry for it), and
> it is only in the ConditionHolds pseudocode that you can see how this
> is actually special-cased.
>
> So I'm fine leaving the code as it is, but a comment and a pointer to
> the ARMv8 ARM wouldn't go amiss.
>
> Thanks,
>
> 	M.
>

OK.

-dl

WARNING: multiple messages have this Message-ID (diff)
From: dave.long@linaro.org (David Long)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v11 4/9] arm64: add conditional instruction simulation support
Date: Mon, 21 Mar 2016 04:35:13 -0400	[thread overview]
Message-ID: <56EFB241.80909@linaro.org> (raw)
In-Reply-To: <20160314073803.22c90d69@arm.com>

On 03/14/2016 03:38 AM, Marc Zyngier wrote:
> On Mon, 14 Mar 2016 09:34:55 +0530
> Pratyush Anand <panand@redhat.com> wrote:
>
> Hi Pratyush,
>
>> On 13/03/2016:12:09:03 PM, Marc Zyngier wrote:
>>> On Wed,  9 Mar 2016 00:32:18 -0500
>>> David Long <dave.long@linaro.org> wrote:
>>>
>>>> +pstate_check_t * const opcode_condition_checks[16] = {
>>>> +	__check_eq, __check_ne, __check_cs, __check_cc,
>>>> +	__check_mi, __check_pl, __check_vs, __check_vc,
>>>> +	__check_hi, __check_ls, __check_ge, __check_lt,
>>>> +	__check_gt, __check_le, __check_al, __check_al
>>>
>>> The very last entry seems wrong, or is at least the opposite of what
>>> the current code has. It should be something called __check_nv(), and
>>> always return false (condition code NEVER).
>>
>> May be __check_nv() name is more appropriate as per definition, but shouldn't it
>> still return true, because TRM says:
>> "The condition code NV exists only to provide a valid disassembly of the 0b1111
>> encoding, otherwise its behavior is identical to AL"
>
> Indeed, I missed that. But this interpretation is for the A64
> instruction set, and this array is also used by the new
> arm32_check_condition. The condition code table for A32 seems to
> completely ignore the 0b1111 code (there is simply no entry for it), and
> it is only in the ConditionHolds pseudocode that you can see how this
> is actually special-cased.
>
> So I'm fine leaving the code as it is, but a comment and a pointer to
> the ARMv8 ARM wouldn't go amiss.
>
> Thanks,
>
> 	M.
>

OK.

-dl

  reply	other threads:[~2016-03-21  8:35 UTC|newest]

Thread overview: 76+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-03-09  5:32 [PATCH v11 0/9] arm64: Add kernel probes (kprobes) support David Long
2016-03-09  5:32 ` David Long
2016-03-09  5:32 ` [PATCH v11 1/9] arm64: Add HAVE_REGS_AND_STACK_ACCESS_API feature David Long
2016-03-09  5:32   ` David Long
2016-03-11 18:07   ` James Morse
2016-03-11 18:07     ` James Morse
2016-03-18 13:06     ` David Long
2016-03-18 13:06       ` David Long
2016-03-15 11:04   ` Marc Zyngier
2016-03-15 11:04     ` Marc Zyngier
2016-03-21  7:08     ` David Long
2016-03-21  7:08       ` David Long
2016-03-09  5:32 ` [PATCH v11 2/9] arm64: Add more test functions to insn.c David Long
2016-03-09  5:32   ` David Long
2016-03-09  5:32 ` [PATCH v11 3/9] arm64: add copy_to/from_user to kprobes blacklist David Long
2016-03-09  5:32   ` David Long
2016-03-15 18:47   ` James Morse
2016-03-15 18:47     ` James Morse
2016-03-16  5:43     ` Pratyush Anand
2016-03-16  5:43       ` Pratyush Anand
2016-03-16 10:27       ` James Morse
2016-03-16 10:27         ` James Morse
2016-03-17  7:57         ` Pratyush Anand
2016-03-17  7:57           ` Pratyush Anand
2016-03-18 13:29           ` Pratyush Anand
2016-03-18 13:29             ` Pratyush Anand
2016-03-18 14:02             ` James Morse
2016-03-18 14:02               ` James Morse
2016-03-18 14:43               ` Pratyush Anand
2016-03-18 14:43                 ` Pratyush Anand
2016-03-18 18:12                 ` James Morse
2016-03-18 18:12                   ` James Morse
2016-03-21  5:17                   ` Pratyush Anand
2016-03-21  5:17                     ` Pratyush Anand
2016-03-21 14:52             ` Will Deacon
2016-03-21 14:52               ` Will Deacon
2016-03-22 16:51               ` Pratyush Anand
2016-03-22 16:51                 ` Pratyush Anand
2016-03-17 12:04   ` 平松雅巳 / HIRAMATU，MASAMI
2016-03-17 12:04     ` 平松雅巳 / HIRAMATU，MASAMI
2016-03-09  5:32 ` [PATCH v11 4/9] arm64: add conditional instruction simulation support David Long
2016-03-09  5:32   ` David Long
2016-03-13 12:09   ` Marc Zyngier
2016-03-13 12:09     ` Marc Zyngier
2016-03-14  4:04     ` Pratyush Anand
2016-03-14  4:04       ` Pratyush Anand
2016-03-14  7:38       ` Marc Zyngier
2016-03-14  7:38         ` Marc Zyngier
2016-03-21  8:35         ` David Long [this message]
2016-03-21  8:35           ` David Long
2016-03-09  5:32 ` [PATCH v11 5/9] arm64: Kprobes with single stepping support David Long
2016-03-09  5:32   ` David Long
2016-04-20  1:29   ` Li Bin
2016-04-20  1:29     ` Li Bin
2016-03-09  5:32 ` [PATCH v11 6/9] arm64: kprobes instruction simulation support David Long
2016-03-09  5:32   ` David Long
2016-03-12  3:56   ` Marc Zyngier
2016-03-12  3:56     ` Marc Zyngier
2016-03-21  9:39     ` David Long
2016-03-21  9:39       ` David Long
2016-03-09  5:32 ` [PATCH v11 7/9] arm64: Add trampoline code for kretprobes David Long
2016-03-09  5:32   ` David Long
2016-03-13 13:52   ` Marc Zyngier
2016-03-13 13:52     ` Marc Zyngier
2016-03-21 13:30     ` David Long
2016-03-21 13:30       ` David Long
2016-03-09  5:32 ` [PATCH v11 8/9] arm64: Add kernel return probes support (kretprobes) David Long
2016-03-09  5:32   ` David Long
2016-03-17 12:22   ` 平松雅巳 / HIRAMATU，MASAMI
2016-03-17 12:22     ` 平松雅巳 / HIRAMATU，MASAMI
2016-03-17 12:58     ` 平松雅巳 / HIRAMATU，MASAMI
2016-03-17 12:58       ` 平松雅巳 / HIRAMATU，MASAMI
2016-03-21 13:33       ` David Long
2016-03-21 13:33         ` David Long
2016-03-09  5:32 ` [PATCH v11 9/9] kprobes: Add arm64 case in kprobe example module David Long
2016-03-09  5:32   ` David Long

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