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From: Josh Poimboeuf <jpoimboe@redhat.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: David Woodhouse <dwmw2@infradead.org>,
	Borislav Petkov <bp@alien8.de>,
	Thomas Gleixner <tglx@linutronix.de>,
	Andi Kleen <andi@firstfloor.org>,
	the arch/x86 maintainers <x86@kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Paul Turner <pjt@google.com>, Andrew Lutomirski <luto@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Tom Lendacky <thomas.lendacky@amd.com>,
	Tim Chen <tim.c.chen@linux.intel.com>,
	Greg Kroah-Hartman <gregkh@linux-foundation.org>,
	Dave Hansen <dave.hansen@intel.com>,
	Jiri Kosina <jikos@kernel.org>, Andi Kleen <ak@linux.intel.com>
Subject: Re: [PATCH] x86/alternatives: Fix optimize_nops() checking
Date: Wed, 10 Jan 2018 15:16:36 -0600	[thread overview]
Message-ID: <20180110211636.nagyyyjkkqd4pkvu@treble> (raw)
In-Reply-To: <CA+55aFxOArsmQqu5B9GZY3c662T-dDEUU1e152GoyXY4Lr3V8A@mail.gmail.com>

On Wed, Jan 10, 2018 at 01:11:48PM -0800, Linus Torvalds wrote:
> On Wed, Jan 10, 2018 at 1:08 PM, David Woodhouse <dwmw2@infradead.org> wrote:
> >
> > There are a few of the form 'call *somefunc'.
> >
> > The existing code handles them not by virtue of the relocs, as I said,
> > but by a simple delta of the old and new location of the instruction.
> >
> > But it only does so for the *first* instruction of the altinstr, if it
> > happens to be a (4-byte?) branch.
> 
> Ugh. That's nasty.
> 
> Wouldn't it be much better to simply do it as part of relocation instead?

Not possible, the relocations are applied during vmlinux linking.

-- 
Josh

  reply	other threads:[~2018-01-10 21:16 UTC|newest]

Thread overview: 44+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-01-10  0:31 [PATCH] x86/retpoline: Fix NOSPEC_JMP for tip Andi Kleen
2018-01-10  0:39 ` Thomas Gleixner
2018-01-10  0:39 ` Linus Torvalds
2018-01-10  0:40   ` Thomas Gleixner
2018-01-10  0:45     ` Tom Lendacky
2018-01-10  0:50       ` Thomas Gleixner
2018-01-10  1:30       ` Andi Kleen
2018-01-10  1:36         ` Andi Kleen
2018-01-10  1:50           ` Thomas Gleixner
2018-01-10  1:57             ` Andi Kleen
2018-01-10  9:05         ` David Woodhouse
2018-01-10  0:51   ` Andi Kleen
2018-01-10  1:05     ` Thomas Gleixner
2018-01-10  7:15   ` David Woodhouse
2018-01-10 10:05     ` David Woodhouse
2018-01-10 11:28       ` [PATCH] x86/alternatives: Fix optimize_nops() checking Borislav Petkov
2018-01-10 11:36         ` David Woodhouse
2018-01-10 11:45           ` Borislav Petkov
2018-01-10 11:49             ` David Woodhouse
2018-01-10 11:57               ` Borislav Petkov
2018-01-10 11:58                 ` David Woodhouse
2018-01-10 17:33         ` [tip:x86/pti] " tip-bot for Borislav Petkov
2018-01-10 18:12         ` tip-bot for Borislav Petkov
2018-01-10 18:39         ` tip-bot for Borislav Petkov
2018-01-10 19:38         ` [PATCH] " Linus Torvalds
2018-01-10 19:55           ` Thomas Gleixner
2018-01-10 20:15             ` Josh Poimboeuf
2018-01-10 20:19               ` David Woodhouse
2018-01-10 20:26               ` Linus Torvalds
2018-01-10 20:33                 ` Peter Zijlstra
2018-01-10 20:36                   ` David Woodhouse
2018-01-10 20:49                   ` Linus Torvalds
2018-01-10 20:55                 ` Borislav Petkov
2018-01-10 21:05                   ` Linus Torvalds
2018-01-10 21:08                     ` David Woodhouse
2018-01-10 21:11                       ` Linus Torvalds
2018-01-10 21:16                         ` Josh Poimboeuf [this message]
2018-01-10 21:17                         ` Linus Torvalds
2018-01-10 21:27                           ` Josh Poimboeuf
2018-01-10 21:10                     ` Borislav Petkov
2018-01-10 20:55                 ` Josh Poimboeuf
2018-01-10 20:05           ` Borislav Petkov
2018-01-10 20:20             ` Linus Torvalds
2018-01-10 20:50               ` Borislav Petkov

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