linux-kernel - Re: [PATCH 00/15] x86: Enable FSGSBASE instructions

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Message-ID: <CC541B7E-C639-49EA-A6D9-626E5C2F6723@intel.com>
Date:   Wed, 21 Mar 2018 15:15:35 +0000
From:   "Bae, Chang Seok" <chang.seok.bae@...el.com>
To:     Andy Lutomirski <luto@...nel.org>
CC:     X86 ML <x86@...nel.org>, Andi Kleen <ak@...ux.intel.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        "Metzger, Markus T" <markus.t.metzger@...el.com>,
        "Luck, Tony" <tony.luck@...el.com>,
        "Shankar, Ravi V" <ravi.v.shankar@...el.com>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 00/15] x86: Enable FSGSBASE instructions

> Summary please.

These deltas I found as comparing with your old codes [4]
* Paranoid entry changes to avoid vulnerability 
* Ptrace changes to support the legacy behavior (conditionally)
* Dropped [1] to be aligned with what is concluded in [3]
* Dropped [2] since save_fsgs() doesn’t copy base when index is zero; now open code with FSGSBASE instructions.
* Re-wrote assembly macros and dropped (redundant) SWAPGS intrinsic
* Revised helper functions -- dropped unused helpers and factor out write_task_fs/gsbase
* Introducing all of helper functions at the beginning of patch series
* Factor out load_fsgs()
* One of the test cases will be included later (as published 15 patches already)

[1] Refresh FS and GS when modify_ldt changes an entry
https://git.kernel.org/pub/scm/linux/kernel/git/luto/linux.git/commit/?h=x86/fsgsbase&id=fbe2c2a0ba5b879f8229ca7dfc0d434dbe31a805
[2] When copying a thread, safe FS and GS for real
https://git.kernel.org/pub/scm/linux/kernel/git/luto/linux.git/commit/?h=x86/fsgsbase&id=e51eceeefbd587b514ca357b745b46e8e2746d34 
[3] FSGSBASE ABI discussion
https://marc.info/?l=linux-kernel&m=150212735223392&w=2 
[4] https://git.kernel.org/pub/scm/linux/kernel/git/luto/linux.git/log/?h=x86/fsgsbase