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

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Date:	Sun, 2 Sep 2012 09:30:30 -0700
From:	Dan Carpenter <dan.carpenter@...cle.com>
To:	Kent Yoder <key@...ux.vnet.ibm.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 02:21:55PM -0500, Kent Yoder wrote:
> 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.
> 

Sparse finds that bug as well.  ;)

drivers/acpi/acpica/tbfadt.c:247:15: warning: incorrect type in assignment (different address spaces)
drivers/acpi/acpica/tbfadt.c:247:15:    expected struct acpi_table_header *table
drivers/acpi/acpica/tbfadt.c:247:15:    got void [noderef] <asn:2>*
drivers/acpi/acpica/tbfadt.c:266:30: warning: incorrect type in argument 1 (different address spaces)
drivers/acpi/acpica/tbfadt.c:266:30:    expected void [noderef] <asn:2>*logical_address
drivers/acpi/acpica/tbfadt.c:266:30:    got struct acpi_table_header *table

It should be memcpy_fromio() probably.

regards,
dan carpenter

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