linux-kernel - Re: [PATCH 3/7] PCI PM: Fix saving of device state in pci_legacy

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:	Thu, 05 Feb 2009 12:29:23 +1100
From:	Benjamin Herrenschmidt <benh@...nel.crashing.org>
To:	michael@...erman.id.au
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Frans Pop <elendil@...net.nl>, rjw@...k.pl,
	jbarnes@...tuousgeek.org, linux-pm@...ts.linux-foundation.org,
	linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org
Subject: Re: [PATCH 3/7] PCI PM: Fix saving of device state in
 pci_legacy_suspend

> > Yup, missed that change in the patch. In fact, I even missed the
> > existence of a WARN_ONCE that takes those text arguments... baaaah. I
> > suppose I should try to read more of lkml :-)
> 
> But don't expect to see them on powerpc, they never make it to the
> console.

Allright, that's the problem with our implementation of WARN using a
conditional trap, we don't carry all the variable arguments for the
printf over.

I'm tempted to turn our implementation back to normal C code with an if
and a branch out of line, but Michael seems to say that even with
appropriate use of unlikely() etc... gcc decides to generate the worst
possible code every single time ...

<rant>
such as always inlining the whole printf mumbo jumbo and having the
not-warning case branch over it, not -all- CPUs have good branch
prediction dude, so the icache is going to scream but gcc folks know
better of course....
</rant>

Anyway, I'll see Michael what exactly the situation is here and if we
can fix it a way or another.

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/