From: Eric Anholt <eric@anholt.net>
To: David Airlie <airlied@linux.ie>
Cc: linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org,
"Gustavo A. R. Silva" <gustavo@embeddedor.com>
Subject: Re: [PATCH v2] drm/pl111: Use 64-bit arithmetic instead of 32-bit
Date: Tue, 17 Jul 2018 11:40:07 -0700 [thread overview]
Message-ID: <87d0vlg0zc.fsf@anholt.net> (raw)
In-Reply-To: <20180704142255.GA8614@embeddedor.com>
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"Gustavo A. R. Silva" <gustavo@embeddedor.com> writes:
> Add suffix ULL to constant 1000 in order to give the compiler complete
> information about the proper arithmetic to use.
>
> Notice that such constant is used in a context that expects an
> expression of type u64 (64 bits, unsigned) and the following
> expression is currently being evaluated using 32-bit arithmetic:
>
> mode->clock * 1000
>
> Addresses-Coverity-ID: 1466139 ("Unintentional integer overflow")
> Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
This is silly. The clock won't be over 4ghz -- we haven't seen anything
over 1024x768 on this hardware as far as I know. The u64 is for the
multiplication by width/height below.
I've still applied the patch to shut up the tool.
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WARNING: multiple messages have this Message-ID (diff)
From: Eric Anholt <eric@anholt.net>
To: "Gustavo A. R. Silva" <gustavo@embeddedor.com>,
David Airlie <airlied@linux.ie>
Cc: dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org,
"Gustavo A. R. Silva" <gustavo@embeddedor.com>
Subject: Re: [PATCH v2] drm/pl111: Use 64-bit arithmetic instead of 32-bit
Date: Tue, 17 Jul 2018 11:40:07 -0700 [thread overview]
Message-ID: <87d0vlg0zc.fsf@anholt.net> (raw)
In-Reply-To: <20180704142255.GA8614@embeddedor.com>
[-- Attachment #1: Type: text/plain, Size: 763 bytes --]
"Gustavo A. R. Silva" <gustavo@embeddedor.com> writes:
> Add suffix ULL to constant 1000 in order to give the compiler complete
> information about the proper arithmetic to use.
>
> Notice that such constant is used in a context that expects an
> expression of type u64 (64 bits, unsigned) and the following
> expression is currently being evaluated using 32-bit arithmetic:
>
> mode->clock * 1000
>
> Addresses-Coverity-ID: 1466139 ("Unintentional integer overflow")
> Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
This is silly. The clock won't be over 4ghz -- we haven't seen anything
over 1024x768 on this hardware as far as I know. The u64 is for the
multiplication by width/height below.
I've still applied the patch to shut up the tool.
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next prev parent reply other threads:[~2018-07-17 18:40 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-04 14:22 [PATCH v2] drm/pl111: Use 64-bit arithmetic instead of 32-bit Gustavo A. R. Silva
2018-07-17 18:40 ` Eric Anholt [this message]
2018-07-17 18:40 ` Eric Anholt
2018-07-17 19:52 ` Gustavo A. R. Silva
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