linux-kernel - Re: [PATCH] tpm: fix tpm_acpi sparse warning on different address spaces

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Message-ID: <20120830192155.GA25524@linux.vnet.ibm.com>
Date:	Thu, 30 Aug 2012 14:21:55 -0500
From:	Kent Yoder <key@...ux.vnet.ibm.com>
To:	Dan Carpenter <dan.carpenter@...cle.com>
Cc:	James Morris <jmorris@...ei.org>, linux-kernel@...r.kernel.org,
	linux-security-module@...r.kernel.org,
	tpmdd-devel@...ts.sourceforge.net, kernel-janitors@...r.kernel.org,
	Fengguang Wu <fengguang.wu@...el.com>
Subject: Re: [PATCH] tpm: fix tpm_acpi sparse warning on different address
 spaces

On Thu, Aug 30, 2012 at 10:45:56AM -0700, Dan Carpenter wrote:
> On Thu, Aug 30, 2012 at 09:38:41AM -0500, Kent Yoder wrote:
> > acpi_os_map_memory expects its return value to be in the __iomem address
> > space. Cast it back later when used in a memcpy to avoid the same sparse
> > warning there.
> > 
> > Signed-off-by: Kent Yoder <key@...ux.vnet.ibm.com>
> 
> I can't download linux-next right now but I don't think this is the
> correct fix.  I don't think you can memcpy() directly from __iomem.
> The static checker is warning about a valid bug which should be
> addressed instead of just casted away and silenced.

  I took a look at other uses of the return from acpi_os_map_memory(),
such as acpi_tb_parse_fadt(), which passes the returned pointer to
acpi_tb_create_local_fadt(), which uses ACPI_MEMCPY on it, which is just
memcpy.  This code lives in drivers/acpi.

Kent

> 
> regards,
> dan carpenter
> 
> 

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