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From: Peter Zijlstra <peterz@infradead.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Borislav Petkov <bp@alien8.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>,
	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 21:33:52 +0100	[thread overview]
Message-ID: <20180110203352.GS6176@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <CA+55aFzMzBwtfO1e=eC6oCx9mMMXPoRko0FvKKJrriUGqyQtEg@mail.gmail.com>

On Wed, Jan 10, 2018 at 12:26:25PM -0800, Linus Torvalds wrote:
> Imagine just how crazy that would be to debug. You'd be basically
> executing insane code, and looking at the sources - or even the
> binaries - it would _look_ completely sane.

Been there done that.. we have too much self modifying code for that
not to have been needed.

Use gdb on /proc/kcore and disassemble self to see the _real_ code.

But yes, tricky stuff. Not arguing we need relocations in alternatives,
just saying debugging them (and static keys and others) is great fun.

  reply	other threads:[~2018-01-10 21:44 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 [this message]
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
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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