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From: Catalin Marinas <catalin.marinas@arm.com>
To: Michal Orzel <michal.orzel@arm.com>
Cc: Will Deacon <will@kernel.org>,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, bertrand.marquis@arm.com
Subject: Re: [PATCH] arm64: cputype: Avoid overflow using MIDR_IMPLEMENTOR_MASK
Date: Wed, 4 May 2022 11:52:03 +0100	[thread overview]
Message-ID: <YnJa087yFSv/RAuf@arm.com> (raw)
In-Reply-To: <20220426070603.56031-1-michal.orzel@arm.com>

On Tue, Apr 26, 2022 at 09:06:03AM +0200, Michal Orzel wrote:
> Value of macro MIDR_IMPLEMENTOR_MASK exceeds the range of integer
> and can lead to overflow. Currently there is no issue as it is used
> in expressions implicitly casting it to u32. To avoid possible
> problems, fix the macro.
> 
> Signed-off-by: Michal Orzel <michal.orzel@arm.com>
> ---
> Should we also add a U suffix to ARM_CPU_IMP_* macros that are also shifted
> by MIDR_IMPLEMENTOR_SHIFT? None of them has bit 7 set but we could take some
> precaution steps.

I'm ok with not adding it now. We haven't been consistent with this but
we did encounter a few issues in the past with other bits and only fixed
those that were touching bit 31.

-- 
Catalin

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WARNING: multiple messages have this Message-ID (diff)
From: Catalin Marinas <catalin.marinas@arm.com>
To: Michal Orzel <michal.orzel@arm.com>
Cc: Will Deacon <will@kernel.org>,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, bertrand.marquis@arm.com
Subject: Re: [PATCH] arm64: cputype: Avoid overflow using MIDR_IMPLEMENTOR_MASK
Date: Wed, 4 May 2022 11:52:03 +0100	[thread overview]
Message-ID: <YnJa087yFSv/RAuf@arm.com> (raw)
In-Reply-To: <20220426070603.56031-1-michal.orzel@arm.com>

On Tue, Apr 26, 2022 at 09:06:03AM +0200, Michal Orzel wrote:
> Value of macro MIDR_IMPLEMENTOR_MASK exceeds the range of integer
> and can lead to overflow. Currently there is no issue as it is used
> in expressions implicitly casting it to u32. To avoid possible
> problems, fix the macro.
> 
> Signed-off-by: Michal Orzel <michal.orzel@arm.com>
> ---
> Should we also add a U suffix to ARM_CPU_IMP_* macros that are also shifted
> by MIDR_IMPLEMENTOR_SHIFT? None of them has bit 7 set but we could take some
> precaution steps.

I'm ok with not adding it now. We haven't been consistent with this but
we did encounter a few issues in the past with other bits and only fixed
those that were touching bit 31.

-- 
Catalin

  reply	other threads:[~2022-05-04 10:53 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-04-26  7:06 [PATCH] arm64: cputype: Avoid overflow using MIDR_IMPLEMENTOR_MASK Michal Orzel
2022-04-26  7:06 ` Michal Orzel
2022-05-04 10:52 ` Catalin Marinas [this message]
2022-05-04 10:52   ` Catalin Marinas
2022-05-04 19:57 ` Catalin Marinas
2022-05-04 19:57   ` Catalin Marinas

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