linux-kernel - Re: [PATCH 7/7] x86: Tell about irq stack coverage

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Wed, 25 Sep 2013 18:26:47 -0700
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Joe Perches <joe@...ches.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Paul Mackerras <paulus@....ibm.com>,
	Ingo Molnar <mingo@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Peter Zijlstra <peterz@...radead.org>,
	"H. Peter Anvin" <hpa@...or.com>,
	James Hogan <james.hogan@...tec.com>,
	"James E.J. Bottomley" <jejb@...isc-linux.org>,
	Helge Deller <deller@....de>,
	Martin Schwidefsky <schwidefsky@...ibm.com>,
	Heiko Carstens <heiko.carstens@...ibm.com>,
	"David S. Miller" <davem@...emloft.net>
Subject: Re: [PATCH 7/7] x86: Tell about irq stack coverage

On Wed, Sep 25, 2013 at 5:40 PM, Joe Perches <joe@...ches.com> wrote:
>
> Huh?  That matches all the ARCH_HAS_<foo> patterns.

Right. And they are all crap. lib/string.c is a prime example of
something that should never have happened.

The ARCH_HAS_xyz pattern is totally retarded. It's wrong.

For big conceptual features, we should use Kconfig symbols.

And for smaller things - like lib/string.c - where we have
compatibility fallback functions but want architectures able to
override them with optimized ones one function at a time, we should
either use weak functions (appropriate for some cases), or the symbol
that protects them should the the SAME SYMBOL WE USE. Rather than some
made-up crap-for-brains new ARCH_HAS_xyz symbol. That way it shows up
in greps, and that way we don't have any question about what random
symbol pattern we use that particular day.

So for *bad* use, see lib/string.c, and the ARCH_AS_xyz horror.

For *good* use, see lib/div64.c or lib/find_next_bit.c.

Notice how div64.c doesn't make up new ARCH_HAS_random_crap names? And
no, you don't have to define those things as macros, you can define
them as functions (inline or not), and then just do

    #define find_next_zero_bit find_next_zero_bit

to tell the rest of the world "Look, I have this defined".

The whole "make up a totally unrelated second name for it" means that
we have things like __HAVE_ARCH_STRLEN but also things like
ARCH_HAS_PREFETCHW. Ugh.

                       Linus
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/