From: Richard Henderson <rth@twiddle.net>
To: Aurelien Jarno <aurelien@aurel32.net>
Cc: leon.alrae@imgtec.com, qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [PATCH v2 1/3] target-mips: Copy restrictions from ext/ins to dext/dins
Date: Mon, 3 Aug 2015 14:41:45 -0700 [thread overview]
Message-ID: <55BFE019.2080504@twiddle.net> (raw)
In-Reply-To: <20150803213128.GA19612@aurel32.net>
On 08/03/2015 02:31 PM, Aurelien Jarno wrote:
> On 2015-08-03 12:35, Richard Henderson wrote:
>> if (msb != 31) {
>> - tcg_gen_andi_tl(t0, t0, (1 << (msb + 1)) - 1);
>> + tcg_gen_andi_tl(t0, t0, (1U << (msb + 1)) - 1);
>
> Is this change really needed?
msb == 30 means 1 << 31. Which officially must be unsigned to be correct. If
we were to run under ubsan, this would trigger an error.
> Note that DEXT can't fail as both lsb and msb are in the range 0..31.
> DEXTU and DEXTM can.
...
> The same way DINSM can't fail.
Yes, I know. But it seems cleaner to do the checks always, unifying all of the
code.
> Should we try to get this one into 2.4, if not already too late?
Perhaps. Otherwise via stable after the fact.
r~
next prev parent reply other threads:[~2015-08-03 21:41 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-08-03 18:49 [Qemu-devel] [PATCH 0/3] target-mips fixes Richard Henderson
2015-08-03 18:49 ` [Qemu-devel] [PATCH 1/3] target-mips: Copy restrictions from ext/ins to dext/dins Richard Henderson
2015-08-03 19:29 ` Richard Henderson
2015-08-03 19:35 ` [Qemu-devel] [PATCH v2 " Richard Henderson
2015-08-03 21:31 ` Aurelien Jarno
2015-08-03 21:41 ` Richard Henderson [this message]
2015-08-03 22:09 ` Aurelien Jarno
2015-08-04 8:22 ` Leon Alrae
2015-08-04 10:49 ` Leon Alrae
2015-08-03 18:49 ` [Qemu-devel] [PATCH 2/3] target-mips: Stop translation after unconditional exceptions Richard Henderson
2015-08-03 21:31 ` Aurelien Jarno
2015-08-03 21:47 ` Richard Henderson
2015-08-03 18:49 ` [Qemu-devel] [PATCH 3/3] target-mips: Use CPU_LOG_INT for logging related to interrupts Richard Henderson
2015-08-03 21:31 ` Aurelien Jarno
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