From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: ARC-Seal: i=1; a=rsa-sha256; t=1518126616; cv=none; d=google.com; s=arc-20160816; b=0nSkK0+oLTayLTvuNykv1jWl1243QSWWNueOx8Amph4FBgjhJJREvgaV4QhKtvvDb9 THdoa42NrEBRoOaVp5xkxRrlSK5meue1acgZtt9bSQlCxOJWDHmbri+Qyp4kRTyy5d6N YaI6aXtD8KjpcNxgMQs3V/WMFHNkQmnsI4t7d1GR1M3jfOuUeTwECylhDuZQSuoIWymN apT08I6cDSeqP1G4ZgJ7Uqg57BQnUxYM54TXF+kwp9mfuA05b7nNQZZJQ+ZNuOuSHtvU bX5DkrM1JBuXjs/G7B/aLD7oU0JLMJTLJin5zqZ2BVYYm8P/d2BO/t27N5CfX4CwmyrF wf7Q== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=cc:to:subject:message-id:date:from:references:in-reply-to:sender :mime-version:dkim-signature:arc-authentication-results; bh=hljc5hBHUQYv0kg9gxsCVdsI336KPxWtm5Oru1wG9wc=; b=zDEPpCmqAVXOctNpPUNhfRU30EHKJbtttCuHrs3COS/T0zLzCNgaOeWSZD+fZ+Hk7/ zwN6wjsONtcdPuutZbfnkm8MpuEGqJnF/n9VBLBIO2Qy1gmz87J/8Q/3LhyyAsESJokF syOnRsEhAn5KESLAmJJjHCyxTM5eRZbd/3f4wZdxXi16hp1jmqgHoYNv9heeMIM/Wr5y 3XgYsZVQY5fhrTAiUb0HRMb72Itq2iLzXf/2QxRInHy/Ywm8m5oWI2Z7kAbCNygMS/BP ip7zWffj+G31Lkb+xB7KhA1RI7VWRb8Fcs+VyM7wlj3928MFJawsacce5BqVP6r0jCE8 +OHQ== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=IQcuOFZk; spf=pass (google.com: domain of arndbergmann@gmail.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=arndbergmann@gmail.com Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=IQcuOFZk; spf=pass (google.com: domain of arndbergmann@gmail.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=arndbergmann@gmail.com X-Google-Smtp-Source: AH8x224ZXyFpcD+Cb199besxPQeqcjjik4ofpSl6fGDZ9xpv0AmUbqMEIs/Gm1q94QTtYv7oQc9snSLDKESxVicfQY0= MIME-Version: 1.0 Sender: arndbergmann@gmail.com In-Reply-To: References: <1517950494.3677.30.camel@infradead.org> <201802070918.18978.linux@rainbow-software.org> <20180208134908.4b516794@alans-desktop> <63ca28c5acb64de5ba33a81b6da5c507@AcuMS.aculab.com> From: Arnd Bergmann Date: Thu, 8 Feb 2018 22:50:15 +0100 X-Google-Sender-Auth: SJYGRsGwGaXq_XgC5EiX6abtH8Q Message-ID: Subject: Re: [BUG] x86 : i486 reporting to be vulnerable to Meltdown/Spectre_V1/Spectre_V2 To: whiteheadm@acm.org Cc: David Laight , Alan Cox , Ondrej Zary , David Woodhouse , Guenter Roeck , Greg Kroah-Hartman , Hugh Dickins , Dave Hansen , Jiri Kosina , Borislav Petkov , Kees Cook , Jamie Iles , Eduardo Valentin , Laura Abbott , Rik van Riel , Thomas Gleixner , Linux Kernel Mailing List Content-Type: text/plain; charset="UTF-8" X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1591354140743903681?= X-GMAIL-MSGID: =?utf-8?q?1591871134906430437?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: On Thu, Feb 8, 2018 at 6:27 PM, tedheadster wrote: > On Thu, Feb 8, 2018 at 12:02 PM, David Laight wrote: >> From: Arnd Bergmann >>> Sent: 08 February 2018 15:23 >> ... >>> The Winchip is what eventually turned into the VIA Nano, which does >>> have speculative execution, but I don't think the earlier C3 and C7 did, >>> they are much closer to the original Winchip design. >> >> We had terrible trouble getting (IIRC) the C7 to execute functions >> that were called in 16bit mode and returned in 32bit mode and v.v. >> (for boot code bios calls). >> The problems seemed to imply that it was caching return addresses >> and the translation (to uops) of the instructions that followed. >> So it would effectively decode the first few bytes in the wrong mode. >> So there might be scope for one of these attacks. >> >> OTOH these devices were so slow that I doubt any are used for anything >> serious - and certainly won't get a kernel update even if they are. >> >> Also worth nothing that the difference between the cpu and memory >> speeds is much lower - so far fewer instructions could be speculatively >> executed while waiting a cache miss. > > You might think this absolutely crazy, but I would be willing to test > such systems if I can get my hands on the needed hardware that I lack. > I am already doing sanity testing on Intel > i486/i586/i586-MMX/i686-PentiumPro systems, I just don't have the > clone cpus (Cyrix, etc). VIA machines are available for pocket change in many countries, this one is what I'd get if I wanted to test over here: http://www.ebay.de/itm/IGEL-UD2-D200-VIA-C7-M-500MHz-1GB-1GB-Flash-Memory-Thin-Client-ohne-Netzteil/301860030372 Similarly, the 6x86 (Cyrix, ST or IBM branded are identical) is really easy to get by itself and should fit in many Socket 7 mainboards, which you apparently already have. Arnd