From: Borislav Petkov <bp@alien8.de>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
David Woodhouse <dwmw2@infradead.org>,
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 21:55:44 +0100 [thread overview]
Message-ID: <20180110205544.k2e534nkk27lkpjc@pd.tnic> (raw)
In-Reply-To: <CA+55aFzMzBwtfO1e=eC6oCx9mMMXPoRko0FvKKJrriUGqyQtEg@mail.gmail.com>
On Wed, Jan 10, 2018 at 12:26:25PM -0800, Linus Torvalds wrote:
> > I think Boris had a patch floating around to add an instruction decoder
> > to alternatives, so you can do a call/jmp anywhere.
>
> .. and no, we're not doing that. Christ.
>
> People, we need to try to be *robust* here. That's doubly (triply!)
> true of things like altinstructions where people - very much by design
> - won't even *test* the alternatives very much, because very much by
> design the altinstructions are only used on certain architectures or
> in certain situations.
Ok, so the problem was: how to fixup jumps which are not the first
instruction which is being replaced but a following one in the
instruction bytes with which we replace.
I used the insn decoder to get insn boundaries so that I can know
whether bytes 0xeb or 0xe9 are the actual JMP opcode and not some other
bytes from the stream.
So how do you suggest I do that without the decoder? I still need some
sort of parsing to find out where the boundaries are...
Thx.
--
Regards/Gruss,
Boris.
Good mailing practices for 400: avoid top-posting and trim the reply.
next prev parent reply other threads:[~2018-01-10 20:55 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 [this message]
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
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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