All of lore.kernel.org
 help / color / mirror / Atom feed
From: Thomas Gleixner <tglx@linutronix.de>
To: Andy Lutomirski <luto@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
	Peter Zijlstra <peterz@infradead.org>,
	the arch/x86 maintainers <x86@kernel.org>,
	Borislav Petkov <bp@alien8.de>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Adrian Hunter <adrian.hunter@intel.com>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	Joerg Roedel <joro@8bytes.org>, Jiri Olsa <jolsa@redhat.com>,
	Andi Kleen <ak@linux.intel.com>
Subject: Re: [PATCH v2 3/3] x86/pti/64: Remove the SYSCALL64 entry trampoline
Date: Sat, 8 Sep 2018 08:36:03 +0200 (CEST)	[thread overview]
Message-ID: <alpine.DEB.2.21.1809080833580.1402@nanos.tec.linutronix.de> (raw)
In-Reply-To: <CALCETrXw9kjeGTrGBy=VMV_2pqAUC4bRZVMgvTrqkZ-EzO80_A@mail.gmail.com>

On Fri, 7 Sep 2018, Andy Lutomirski wrote:
> On Fri, Sep 7, 2018 at 5:04 PM, Linus Torvalds
> <torvalds@linux-foundation.org> wrote:
> > Virtual mapping tricks may be cool, but in the end, not having to use
> > them is better still, I think.
> >
> 
> If (and this is a *big* if) all the percpu data is within 2GB of the
> entry text, then we could avoid this extra TLB reference by accessing
> it directly instead of using an alias.
> 
> I suppose the summary is that the retpoline-free trampoline variant is
> even more complicated than the code I'm removing in this series, and
> that it would be at best a teeny tiny win.  Once all the Spectre dust
> settles and we get fixed CPUs, we could consider re-optimizing this.

That's going to be after my retirement ...



  reply	other threads:[~2018-09-08  6:36 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-09-03 22:59 [PATCH v2 0/3] x86/pti: Get rid of entry trampolines and add some docs Andy Lutomirski
2018-09-03 22:59 ` [PATCH v2 1/3] x86/entry/64: Document idtentry Andy Lutomirski
2018-09-06  9:50   ` Borislav Petkov
2018-09-08  9:33   ` [tip:x86/pti] " tip-bot for Andy Lutomirski
2018-09-03 22:59 ` [PATCH v2 2/3] x86/entry/64: Use the TSS sp2 slot for SYSCALL/SYSRET scratch space Andy Lutomirski
2018-09-07  8:00   ` Borislav Petkov
2018-09-08  9:34   ` [tip:x86/pti] " tip-bot for Andy Lutomirski
2018-09-03 22:59 ` [PATCH v2 3/3] x86/pti/64: Remove the SYSCALL64 entry trampoline Andy Lutomirski
2018-09-04  7:04   ` Peter Zijlstra
2018-09-05 21:31     ` Andy Lutomirski
2018-09-07 12:36       ` Peter Zijlstra
2018-09-07 19:54       ` Thomas Gleixner
2018-09-08  0:04         ` Linus Torvalds
2018-09-08  4:32           ` Andy Lutomirski
2018-09-08  6:36             ` Thomas Gleixner [this message]
2018-09-08  6:33           ` Thomas Gleixner
2018-09-07  9:35   ` Borislav Petkov
2018-09-07 16:40   ` Josh Poimboeuf
2018-09-08  4:35     ` Andy Lutomirski
2018-09-08  9:35   ` [tip:x86/pti] " tip-bot for Andy Lutomirski
2018-09-08  9:57   ` tip-bot for Andy Lutomirski
2018-09-12 19:33   ` tip-bot for Andy Lutomirski
2018-09-12 19:36   ` tip-bot for Andy Lutomirski
2018-09-04  3:43 ` [PATCH v2 0/3] x86/pti: Get rid of entry trampolines and add some docs Linus Torvalds

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=alpine.DEB.2.21.1809080833580.1402@nanos.tec.linutronix.de \
    --to=tglx@linutronix.de \
    --cc=acme@kernel.org \
    --cc=adrian.hunter@intel.com \
    --cc=ak@linux.intel.com \
    --cc=alexander.shishkin@linux.intel.com \
    --cc=bp@alien8.de \
    --cc=dave.hansen@linux.intel.com \
    --cc=jolsa@redhat.com \
    --cc=joro@8bytes.org \
    --cc=jpoimboe@redhat.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=luto@kernel.org \
    --cc=peterz@infradead.org \
    --cc=torvalds@linux-foundation.org \
    --cc=x86@kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.