From: Andi Kleen <ak@linux.intel.com>
To: Andy Lutomirski <luto@kernel.org>
Cc: "Bae, Chang Seok" <chang.seok.bae@intel.com>,
Ingo Molnar <mingo@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
"H. Peter Anvin" <hpa@zytor.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
"Metzger, Markus T" <markus.t.metzger@intel.com>,
"Ravi V. Shankar" <ravi.v.shankar@intel.com>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [v3 03/12] x86/fsgsbase/64: Add intrinsics/macros for FSGSBASE instructions
Date: Wed, 24 Oct 2018 12:21:37 -0700 [thread overview]
Message-ID: <20181024192137.GI6218@tassilo.jf.intel.com> (raw)
In-Reply-To: <CALCETrWWBYgaJfPykTpJ9=TsptVL_ieOR3JdYVVW02=O9CM17Q@mail.gmail.com>
On Wed, Oct 24, 2018 at 11:53:54AM -0700, Andy Lutomirski wrote:
> On Tue, Oct 23, 2018 at 11:43 AM Chang S. Bae <chang.seok.bae@intel.com> wrote:
> >
> > From: Andi Kleen <ak@linux.intel.com>
> >
> > Add C intrinsics and assembler macros for the new FSBASE and GSBASE
> > instructions.
> >
> > Very straight forward. Used in followon patches.
> >
> > [ luto: Rename the variables from FS and GS to FSBASE and GSBASE and
> > make <asm/fsgsbase.h> safe to include on 32-bit kernels. ]
> >
> > v2: Use __always_inline
> >
> > [ chang: Revise the changelog. Place them in <asm/fsgsbase.h>. Replace
> > the macros with GAS-compatible ones. ]
> >
> > If GCC supports it, we can add -mfsgsbase to CFLAGS and use the builtins
> > here for extra performance.
>
> Reviewed-by: Andy Lutomirski <luto@kernel.org> # C parts only
>
> With the caveat that I'm not convinced that the memory clobbers are
> needed. The __force_order trick in special_insns.h would probably be
> more appropriate.
>
> I don't feel qualified to review the asm part without some research.
> Whereas hpa or Boris could probably review it with their eyes closed.
BTW the other option would be to update the min-binutils requirement
to 2.21 (currently it is 2.20) and then write it directly without .byte.
I believe 2.21 added support for these instructions.
(It's only a binutils requirement, don't need gcc support)
-Andi
next prev parent reply other threads:[~2018-10-24 19:21 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-23 18:42 [v3 00/12] x86: Enable FSGSBASE instructions Chang S. Bae
2018-10-23 18:42 ` [v3 01/12] taint: Introduce a new taint flag (insecure) Chang S. Bae
2018-10-24 18:50 ` Andy Lutomirski
2018-10-23 18:42 ` [v3 02/12] x86/fsgsbase/64: Add 'unsafe_fsgsbase' to enable CR4.FSGSBASE Chang S. Bae
2018-10-24 18:51 ` Andy Lutomirski
2018-10-23 18:42 ` [v3 03/12] x86/fsgsbase/64: Add intrinsics/macros for FSGSBASE instructions Chang S. Bae
2018-10-24 18:53 ` Andy Lutomirski
2018-10-24 19:21 ` Andi Kleen [this message]
2018-10-25 23:14 ` Andy Lutomirski
2018-10-25 23:31 ` Linus Torvalds
2018-10-26 0:09 ` Andy Lutomirski
2018-10-23 18:42 ` [v3 04/12] x86/fsgsbase/64: Enable FSGSBASE instructions in the helper functions Chang S. Bae
2018-10-24 19:16 ` Andy Lutomirski
2018-10-24 19:41 ` [Xen-devel] " Andrew Cooper
2018-10-25 6:09 ` Juergen Gross
2018-10-25 23:08 ` Andrew Cooper
2018-10-25 23:11 ` Andy Lutomirski
2018-10-25 23:14 ` Andrew Cooper
2018-10-25 23:14 ` [Xen-devel] " Andrew Cooper
2018-10-25 23:11 ` Andy Lutomirski
2018-10-25 23:08 ` Andrew Cooper
2018-10-25 6:09 ` Juergen Gross
2018-10-24 19:41 ` Andrew Cooper
2018-10-25 7:32 ` Bae, Chang Seok
2018-10-25 7:32 ` Bae, Chang Seok
2018-10-25 23:00 ` Andy Lutomirski
2018-10-25 23:03 ` Bae, Chang Seok
2018-10-25 23:03 ` Bae, Chang Seok
2018-10-25 23:00 ` Andy Lutomirski
2018-10-25 23:16 ` Andy Lutomirski
2018-10-25 23:16 ` Andy Lutomirski
2018-10-24 19:16 ` Andy Lutomirski
2018-10-23 18:42 ` [v3 05/12] x86/fsgsbase/64: Preserve FS/GS state in __switch_to() if FSGSBASE is on Chang S. Bae
2018-10-24 19:21 ` Andy Lutomirski
2018-10-24 19:36 ` Bae, Chang Seok
2018-10-23 18:42 ` [v3 06/12] x86/fsgsbase/64: When copying a thread, use the FSGSBASE instructions if available Chang S. Bae
2018-10-23 18:42 ` [v3 07/12] x86/fsgsbase/64: Introduce the new FIND_PERCPU_BASE macro Chang S. Bae
2018-10-26 0:25 ` Andy Lutomirski
2018-10-26 0:59 ` Nadav Amit
2018-10-23 18:42 ` [v3 08/12] x86/fsgsbase/64: Use the per-CPU base as GSBASE at the paranoid_entry Chang S. Bae
2018-10-23 18:42 ` [v3 09/12] selftests/x86/fsgsbase: Test WRGSBASE Chang S. Bae
2018-10-23 18:42 ` [v3 10/12] x86/fsgsbase/64: Enable FSGSBASE by default and add a chicken bit Chang S. Bae
2018-10-23 18:42 ` [v3 11/12] x86/elf: Enumerate kernel FSGSBASE capability in AT_HWCAP2 Chang S. Bae
2018-10-23 18:42 ` [v3 12/12] x86/fsgsbase/64: Add documentation for FSGSBASE Chang S. Bae
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