Re: [RFC][PATCH 5/6] x86, efi: Fix endian issues and unalignedaccesses

[Stephen Rothwell]

Hi all,

On Tue, 28 Feb 2012 13:37:24 +0000 Matt Fleming <matt@xxxxxxxxxxxxxxxxx> wrote:
>
> From: Matt Fleming <matt.fleming@xxxxxxxxx>
> 
> We may need to convert the endianness of the data we read from/write
> to 'buf', so let's use {get,put}_unaligned_le32() to do that. Failure
> to do so can result in accessing invalid memory, leading to a
> segfault.  Stephen Rothwell noticed this bug while cross-building an
> x86_64 allmodconfig kernel on PowerPC.
> 
> We need to read from and write to 'buf' a byte at a time otherwise
> it's possible we'll perform an unaligned access, which can lead to bus
> errors when cross-building an x86 kernel on risc architectures.
> 
> Cc: H. Peter Anvin <hpa@xxxxxxxxx>
> Cc: Nick Bowler <nbowler@xxxxxxxxxxxxxxxx>
> Tested-by: Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx>
> Reported-by: Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx>
> Signed-off-by: Matt Fleming <matt.fleming@xxxxxxxxx>

Just to be absolutely clear, I have not yet tested this version of the
patch and also this fixes a problem with cross building Linus' tree (i.e.
this is a regression with cross building introduced in v3.3-rc1).

-- 
Cheers,
Stephen Rothwell                    sfr@xxxxxxxxxxxxxxxx
http://www.canb.auug.org.au/~sfr/

Attachment: pgp00000.pgp
Description: PGP signature