From: Pavel Machek <pavel@ucw.cz>
To: Denys Vlasenko <vda.linux@googlemail.com>
Cc: Brian Gerst <brgerst@gmail.com>, Ingo Molnar <mingo@kernel.org>,
"H. Peter Anvin" <hpa@zytor.com>,
Andy Lutomirski <luto@amacapital.net>,
Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>,
Ingo Molnar <mingo@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>, X86 ML <x86@kernel.org>,
"linux-pm@vger.kernel.org" <linux-pm@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Denys Vlasenko <dvlasenk@redhat.com>,
Borislav Petkov <bp@alien8.de>,
Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH] x86: General protection fault after STR (32 bit systems only)
Date: Sat, 13 Jun 2015 16:20:05 +0200 [thread overview]
Message-ID: <20150613142005.GA29207@amd> (raw)
In-Reply-To: <CAK1hOcPvst1+vT_3_m0t7HZF_fz9zjDd_azyWj6n0Ma-qY3ZQQ@mail.gmail.com>
On Sat 2015-06-13 00:45:29, Denys Vlasenko wrote:
> On Fri, Jun 12, 2015 at 5:48 PM, Brian Gerst <brgerst@gmail.com> wrote:
> > If you follow the convoluted flow of the calls in this file,
> > ...
>
> Speaking of which. It is indeed quite bad.
>
> For one, saved_eip is only ever set to point to ret_point:
>
> ENTRY(saved_eip) .long 0
> ...
>
> movl $ret_point, saved_eip
>
> and it has just a single user, where an indirect jump
> through it is performed:
>
> # jump to place where we left off
> movl saved_eip, %eax
> jmp *%eax
>
> No comments why it is so.
>
> All this seems to be equivalent to trivial
>
> # jump to place where we left off
> jmp ret_point
>
> Am I missing something?
I don't think so. Its just that slowdown was not bad enough tofix it.
...patch would be welcome, and even better if you could check the issue
on 64-bit kernel, too...
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
next prev parent reply other threads:[~2015-06-13 14:20 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-11 23:45 [PATCH] x86: General protection fault after STR (32 bit systems only) Srinivas Pandruvada
2015-06-12 6:07 ` Ingo Molnar
2015-06-12 6:48 ` Andy Lutomirski
2015-06-12 7:15 ` Ingo Molnar
2015-06-12 7:41 ` Andy Lutomirski
2015-06-12 7:50 ` Ingo Molnar
2015-06-12 8:15 ` H. Peter Anvin
2015-06-12 8:36 ` Ingo Molnar
2015-06-12 15:48 ` Brian Gerst
2015-06-12 18:11 ` Andy Lutomirski
2015-06-12 18:31 ` Srinivas Pandruvada
2015-06-13 7:00 ` Ingo Molnar
2015-06-12 22:45 ` Denys Vlasenko
2015-06-13 14:20 ` Pavel Machek [this message]
2015-06-13 7:03 ` Ingo Molnar
2015-06-13 18:23 ` Andy Lutomirski
2015-06-13 21:30 ` Brian Gerst
2015-06-14 6:56 ` [PATCH] x86: Load __USER_DS into DS/ES after resume Ingo Molnar
2015-06-14 7:03 ` Pavel Machek
[not found] ` <CA+55aFzB9dYidEf_7Hs47FOF7WPPJnJQwj_RiwL--c5Gb1uqyw@mail.gmail.com>
2015-06-14 7:49 ` [PATCH v2] " Ingo Molnar
2015-06-14 8:57 ` Pavel Machek
2015-06-14 14:22 ` Brian Gerst
2015-06-15 16:12 ` Srinivas Pandruvada
2015-06-16 9:13 ` Pavel Machek
2015-06-16 21:40 ` Rafael J. Wysocki
2015-06-17 8:59 ` x86: allow using different kernel version for 32-bit, too Pavel Machek
2015-06-18 9:13 ` [PATCH v2] x86: Load __USER_DS into DS/ES after resume Ingo Molnar
2015-06-22 14:06 ` Rafael J. Wysocki
2015-06-12 16:15 ` [PATCH] x86: General protection fault after STR (32 bit systems only) Srinivas Pandruvada
2015-06-13 7:15 ` [PATCH, DEBUG] x86/32: Add small delay after resume Ingo Molnar
2015-06-15 16:10 ` Srinivas Pandruvada
2015-06-16 21:33 ` H. Peter Anvin
2015-06-16 22:25 ` Srinivas Pandruvada
2015-06-17 16:33 ` Konrad Rzeszutek Wilk
2015-06-17 17:22 ` H. Peter Anvin
2015-06-17 18:29 ` Konrad Rzeszutek Wilk
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