linux-kernel - Re: sparse -Wptr-subtraction-blows: still needed?

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]

Message-ID: <p73abwnxtq8.fsf@bingen.suse.de>
Date:	02 May 2007 15:03:59 +0200
From:	Andi Kleen <andi@...stfloor.org>
To:	Dave Jones <davej@...hat.com>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Josh Triplett <josh@...edesktop.org>,
	linux-sparse@...r.kernel.org, linux-kernel@...r.kernel.org,
	Al Viro <viro@....linux.org.uk>
Subject: Re: sparse -Wptr-subtraction-blows: still needed?

Dave Jones <davej@...hat.com> writes:
> 
> #define __page_to_pfn(page)     ((unsigned long)((page) - mem_map) + \
>                                  ARCH_PFN_OFFSET)
> 
> looks like the other two variants of __page_to_pfn also use similar arithmatic.

No way around this. The only way to turn a page into a pfn is to do 
a constant division.  Should be fairly cheap here though.

-Andi (who thinks the sparse warning is dumb; better to look at oprofiles
of hot paths)
-
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/