linux-kernel - Re: [PATCH v2 2/4] devm: fix ioremap

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: <1620292.L8s1FmNDhT@wuerfel>
Date:	Mon, 01 Jun 2015 16:26:57 +0200
From:	Arnd Bergmann <arnd@...db.de>
To:	Dan Williams <dan.j.williams@...el.com>
Cc:	Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
	"H. Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ross Zwisler <ross.zwisler@...ux.intel.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Juergen Gross <jgross@...e.com>, X86 ML <x86@...nel.org>,
	"Kani, Toshimitsu" <toshi.kani@...com>,
	"linux-nvdimm@...ts.01.org" <linux-nvdimm@...ts.01.org>,
	Luis Rodriguez <mcgrof@...e.com>,
	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Stefan Bader <stefan.bader@...onical.com>,
	Andy Lutomirski <luto@...capital.net>, linux-mm@...ck.org,
	geert@...ux-m68k.org, Henrique de Moraes Holschuh <hmh@....eng.br>,
	Tejun Heo <tj@...nel.org>, Christoph Hellwig <hch@....de>
Subject: Re: [PATCH v2 2/4] devm: fix ioremap_cache() usage

On Saturday 30 May 2015 14:16:28 Dan Williams wrote:
> On Sat, May 30, 2015 at 1:52 PM, Arnd Bergmann <arnd@...db.de> wrote:
> > On Saturday 30 May 2015, Dan Williams wrote:
> >> @@ -154,7 +148,7 @@ void __iomem *devm_ioremap_resource(struct device *dev, struct resource *res)
> >>         }
> >>
> >>         if (res->flags & IORESOURCE_CACHEABLE)
> >> -               dest_ptr = devm_ioremap(dev, res->start, size);
> >> +               dest_ptr = devm_ioremap_cache(dev, res->start, size);
> >>         else
> >>                 dest_ptr = devm_ioremap_nocache(dev, res->start, size);
> >
> > I think the existing uses of IORESOURCE_CACHEABLE are mostly bugs, so changing
> > the behavior here may cause more problems than it solves.
> >
> 
> Ok, but that effectively makes devm_ioremap_resource() unusable for
> the cached case.  How about introducing devm_ioremap_cache_resource(),
> and cleaning up devm_ioremap_resource() to stop pretending that it is
> honoring the memory type of the resource?

I was thinking the opposite approach and basically removing all uses
of IORESOURCE_CACHEABLE from the kernel. There are only a handful of
them.and we can probably replace them all with hardcoded ioremap_cached()
calls in the cases they are actually useful

	Arnd
--
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/