linux-kernel - Re: use of fixmap on non-x86/sh?

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:	Sat, 01 Dec 2007 16:15:37 +1100
From:	Benjamin Herrenschmidt <benh@...nel.crashing.org>
To:	Paul Mundt <lethal@...ux-sh.org>
Cc:	Kumar Gala <galak@...nel.crashing.org>, davem@...emloft.net,
	wli@...omorphy.com, mingo@...hat.com, ralf@...ux-mips.org,
	linux-kernel@...r.kernel.org
Subject: Re: use of fixmap on non-x86/sh?

On Sat, 2007-12-01 at 10:03 +0900, Paul Mundt wrote:
> There are of course things that make this more attractive on x86,
> especially with regards to the global bit and preservation across a
> TLB
> flush, there's a note in arch/sh/mm/init.c above __set_fixmap() about
> that. fixmap doesn't really have any special behaviour that makes an
> architecture implementation problematic at least.

On ppc, we are mostly looking into memory mapped config space, which for
some new PCIe bridges is huge (about 512M per port on the 440SPe). Those
processors have 36 bits physical addresses and 32 bits virtual.

So I suppose we can just move our current kmap_atomic implementation out
of highmem, call it fixmap, and add a slot for use by PCI config space
access (those are fully spinlocked, so the per-cpu aspect is just what
we need, just like kmap_atomic).

Ben.

-
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/