From: Richard Henderson <rth@twiddle.net>
To: Paolo Bonzini <pbonzini@redhat.com>, qemu-devel@nongnu.org
Cc: Blue Swirl <blauwirbel@gmail.com>,
peter.maydell@linaro.org,
Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>,
armbru@redhat.com
Subject: Re: [Qemu-devel] [PATCH] target-sparc: fix 32-bit truncation in fpackfix, avoid undefined behavior
Date: Fri, 6 Nov 2015 17:10:00 +0100 [thread overview]
Message-ID: <563CD0D8.4050805@twiddle.net> (raw)
In-Reply-To: <1446825056-7989-1-git-send-email-pbonzini@redhat.com>
On 11/06/2015 04:50 PM, Paolo Bonzini wrote:
> This is reported by Coverity. The algorithm description at
> ftp://ftp.icm.edu.pl/packages/ggi/doc/hw/sparc/Sparc.pdf suggests
> that the 32-bit parts of rs2, after the left shift, is treated
> as a 64-bit integer. Bits 32 and above are used to do the
> saturating truncation.
>
> Use a cast to unsigned in order to placate ubsan for negative
> inputs, and do so in the other fpack* instructions too.
>
> Signed-off-by: Paolo Bonzini<pbonzini@redhat.com>
> ---
> target-sparc/vis_helper.c | 9 ++++++---
> 1 file changed, 6 insertions(+), 3 deletions(-)
Reviewed-by: Richard Henderson <rth@twiddle.net>
r~
next prev parent reply other threads:[~2015-11-06 16:10 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-11-06 15:50 [Qemu-devel] [PATCH] target-sparc: fix 32-bit truncation in fpackfix, avoid undefined behavior Paolo Bonzini
2015-11-06 16:10 ` Richard Henderson [this message]
2015-11-06 16:28 ` Mark Cave-Ayland
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