linux-kernel - Re: [PATCH] USB: ehci: use packed, aligned(4) instead of removing the packed attribute

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:	Mon, 20 Jun 2011 15:29:44 -0400 (EDT)
From:	Nicolas Pitre <nico@...xnic.net>
To:	Russell King - ARM Linux <linux@....linux.org.uk>
Cc:	Arnd Bergmann <arnd@...db.de>,
	Alan Stern <stern@...land.harvard.edu>, gregkh@...e.de,
	linux-usb@...r.kernel.org, lkml <linux-kernel@...r.kernel.org>,
	Rabin Vincent <rabin@....in>,
	Alexander Holler <holler@...oftware.de>,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH] USB: ehci: use packed,
 aligned(4) instead of removing the packed attribute

On Mon, 20 Jun 2011, Russell King - ARM Linux wrote:

> On Mon, Jun 20, 2011 at 06:58:45PM +0200, Arnd Bergmann wrote:
> > We are also going to change the ARM implementation to always do 32 bit
> > accesses in readl/writel, but the patch that went into the ehci driver
> > was correct nonetheless.
> 
> Not without someone doing a comparitively large amount of work to analyze
> the effect of any change there and make sure that it doesn't have a
> negative impact to drivers.

This thread prompted me to investigate a bit.  I have vague memories for 
the reasons why we decided to use plain C for the IO accessors as the 
inline assembly version didn't produce nearly the same code quality.  It 
seems that GCC improved quite a bit there, and from a quick 
investigation, it looks like comparable code is being generated with the 
C and the inline asm versions with a recent enough GCC.  This is 
certainly the case with the version causing issues with packed 
structures.

Nicolas
--
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/