Surely the term "fetch-protected" says it all: In principle you'd fetch protect what you didn't want fetched. :-) Now, I don't know if there is any overhead to fetch protection that might cause you not to fetch protect what should be.
Cheers, Martin Martin Packer zChampion, Systems Investigator & Performance Troubleshooter, IBM +44-7802-245-584 email: [email protected] Twitter / Facebook IDs: MartinPacker Blog: https://www.ibm.com/developerworks/mydeveloperworks/blogs/MartinPacker Podcast Series (With Marna Walle): https://developer.ibm.com/tv/mpt/ or https://itunes.apple.com/gb/podcast/mainframe-performance-topics/id1127943573?mt=2 Youtube channel: https://www.youtube.com/channel/UCu_65HaYgksbF6Q8SQ4oOvA From: "Cannaerts, Jan" <[email protected]> To: [email protected] Date: 04/01/2018 10:11 Subject: Re: Intel Chip flaw Sent by: IBM Mainframe Discussion List <[email protected]> This article: https://urldefense.proofpoint.com/v2/url?u=https-3A__googleprojectzero.blogspot.be_2018_01_reading-2Dprivileged-2Dmemory-2Dwith-2Dside.html&d=DwIFaQ&c=jf_iaSHvJObTbx-siA1ZOg&r=BsPGKdq7-Vl8MW2-WOWZjlZ0NwmcFSpQCLphNznBSDQ&m=JgfLm1WtVuc3hfiKug2jNzxJ50Cb-S25nq4BySZ38Fs&s=z8S5H15LmNsZT976WrrTR3zjzYH6V6IUtFklSLCiQzE&e= Mentions the following: > Additional exploits for other architectures are also known to exist. These > include IBM System Z, POWER8 (Big Endian and Little Endian), and POWER9 > (Little Endian). The attacks target flaws in the hardware, in this case related to speculative execution. But the PoCs I'm seeing so far seem to be meant to leak Linux kernel memory (leaking passwords/cryptographic keys). The z/Architecture also employs speculative execution and branch prediction. So I'm not sure whether or not there is a working PoC for any Linux distribution running either Linux native, under z/VM or KVM on System Z, and I cannot find anything about a PoC for z/OS either. If the attack can be used against z/OS, I'd wager it could leak fetch-protected memory that is addressable by the address space in the first place. How much interesting information there is in fetch-protected storage, I do not know. - Jan ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN Unless stated otherwise above: IBM United Kingdom Limited - Registered in England and Wales with number 741598. Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
