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From: David Woodhouse <dwmw2@infradead.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>,
	the arch/x86 maintainers <x86@kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH 2/3] objtool: Ignore retpoline alternatives
Date: Thu, 11 Jan 2018 17:57:08 +0000	[thread overview]
Message-ID: <1515693428.22302.388.camel@infradead.org> (raw)
In-Reply-To: <CA+55aFzLA2dBhVTsvEBZ58aS2Jgp020cPC3MvMR_RuJqFmM67Q@mail.gmail.com>

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On Thu, 2018-01-11 at 09:29 -0800, Linus Torvalds wrote:
> 
> That, btw, is also why it's pointless to make the small numbers
> "bigger". Using "1122" as a label is actively worse than just using
> "1".

Actually in macros I don't think that's entirely true (depending on the
assembler/preprocessor behaviour, which is often surprising).

You want to use labels in macros which are not going to conflict with
what the human has typed into their .S file. If they have code along
the lines of

 	jnz 1f
	INVOKE_MACRO
1:

... then you surely don't want to be using the label '1' in your macro.

I'm fairly sure that's true if you're using CPP macros (which we seem
to do most of the time even in .S files). It might actually DTRT if you
are using .macro; I'm not sure.

So I will go back to numeric labels, as I said. But not '1:'. :)

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  parent reply	other threads:[~2018-01-11 17:57 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-01-11  1:48 [PATCH 0/3] objtool: retpoline compatibility Josh Poimboeuf
2018-01-11  1:48 ` [PATCH 1/3] objtool: Detect jumps to retpoline thunks Josh Poimboeuf
2018-01-11  1:48 ` [PATCH 2/3] objtool: Ignore retpoline alternatives Josh Poimboeuf
2018-01-11 16:27   ` David Woodhouse
2018-01-11 16:33     ` Josh Poimboeuf
2018-01-11 16:39       ` David Woodhouse
2018-01-11 16:48         ` Josh Poimboeuf
2018-01-11 16:55           ` David Woodhouse
2018-01-11 17:25             ` Josh Poimboeuf
2018-01-11 16:58           ` Peter Zijlstra
2018-01-11 17:05             ` Jiri Kosina
2018-01-11 17:01           ` Jiri Kosina
2018-01-11 17:05             ` Peter Zijlstra
2018-01-11 17:19               ` David Woodhouse
2018-01-11 17:23                 ` Peter Zijlstra
2018-01-11 16:44       ` Peter Zijlstra
2018-01-11 17:29     ` Linus Torvalds
2018-01-11 17:37       ` Josh Poimboeuf
2018-01-11 17:43       ` David Woodhouse
2018-01-11 17:56       ` Peter Zijlstra
2018-01-12 20:36         ` Ingo Molnar
2018-01-11 17:57       ` David Woodhouse [this message]
2018-01-11  1:48 ` [PATCH 3/3] Revert "x86/retpoline: Temporarily disable objtool when CONFIG_RETPOLINE=y" Josh Poimboeuf
2018-01-11 10:22 ` [PATCH 0/3] objtool: retpoline compatibility David Woodhouse

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