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From: Linus Torvalds <torvalds@linux-foundation.org>
To: Ingo Molnar <mingo@kernel.org>
Cc: Peter Anvin <hpa@zytor.com>, Jan Beulich <JBeulich@suse.com>,
	Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@elte.hu>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Tony Jones <tonyj@suse.de>
Subject: Re: [PATCH, RFC] x86: also CFI-annotate certain inline asm()s
Date: Mon, 10 Nov 2014 10:10:01 -0800	[thread overview]
Message-ID: <CA+55aFwZYeFtuQbxtAbOoMVNFN_fQKnxGbRybdz-LYRzwMqX9w@mail.gmail.com> (raw)
In-Reply-To: <CA+55aFw9MV1n8T7_k5oftfY-sOu8s1ywKYM-3k4+PF022vv9ow@mail.gmail.com>

On Mon, Nov 10, 2014 at 9:56 AM, Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>
> So no. A very strong NACK. The code was too ugly to live, there is no good
> stated reason for it, and the only reason I can even remotely imagine is
> wrong and complete crap anyway (ie making the CFI annotations a correctness
> issue by introducing other infrastructure that depends on it always being
> right).

Btw, the sane thing to do is to make your infrastructure just say "If
my frame walker hits a push/pop without CFI information, I'll just add
it myself".

Yes, that involved having to actuall ylook at the instruction. Tough
shit. Just do it right. There aren't that many push/pop patterns.
Don't make the kernel more fragile by introducing these kinds of hacky
macros-from-hell.

Improve the debugger, don't make kernel code worse because your
out-of-tree debugging infrastructure is too broken to live.

                      Linus

  parent reply	other threads:[~2014-11-10 18:10 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-11-04  9:24 [PATCH, RFC] x86: also CFI-annotate certain inline asm()s Jan Beulich
2014-11-04 19:40 ` Andy Lutomirski
2014-11-05 17:13   ` Jan Beulich
2014-11-05 17:23     ` Andy Lutomirski
2014-11-06 10:35       ` Jan Beulich
2014-11-06 17:00         ` Andy Lutomirski
2014-11-10 10:01 ` Ingo Molnar
     [not found]   ` <CA+55aFw9MV1n8T7_k5oftfY-sOu8s1ywKYM-3k4+PF022vv9ow@mail.gmail.com>
2014-11-10 18:10     ` Linus Torvalds [this message]
2014-11-11  7:52       ` Jan Beulich
2014-11-10 18:17     ` Ingo Molnar
2014-11-11  7:42     ` Jan Beulich
2014-11-12 20:36       ` Linus Torvalds
2014-11-13  7:49         ` Jan Beulich

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