linux-kernel - Re: [Bug Fix]: Do 32-bit table calculations in pre-processor

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 for Android: free password hash cracker in your pocket

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

Date:	Fri, 03 Jul 2009 12:48:44 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	lkml@...ethan.org
CC:	Jeremy Fitzhardinge <jeremy@...p.org>,
	linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	the arch/x86 maintainers <x86@...nel.org>,
	Andi Kleen <ak@...ux.intel.com>
Subject: Re: [Bug Fix]: Do 32-bit table calculations in pre-processor

Michael S. Zick wrote:
> 
> Good point: (1<<(32-PAGE_SIFT)) would handle other than 4k pages.
> 
> I just hardcoded it as a working example of the change from setting
> the page table size by design rather than numeric error.
> 

As Jeremy pointed out, it's not wrong as written.  gas by design uses
arbitrary-precision arithmetic, and even if it didn't, it would still be
correct: (1 << 32) would collapse to 0, so all the rest of the
calculations would still be right.

Any way you can dump out this value from the vmlinux file (nm vmlinux |
grep MAPPING_BEYOND_END) in both cases?  What version of as/binutils do
you have installed?

> And yes, it has 512Mbyte of ram, so 1/2Mbyte page table sounds right to me.

/proc/cpuinfo, please?

	-hpa

-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.

--
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/