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Message-ID: <537B07ED.4080104@solarflare.com>
Date: Tue, 20 May 2014 08:44:45 +0100
From: Shradha Shah <sshah@...arflare.com>
To: David Miller <davem@...emloft.net>
CC: "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
linux-net-drivers <linux-net-drivers@...arflare.com>
Subject: [PATCH net 0/2] sfc: Restrict PIO for 64bit arch in order to avoid
data corruption
This patch series
Fixes: ee45fd92c739db5b7950163d91dfe5f016af6d24
The linux net driver uses memcpy_toio() in order to copy into
the PIO buffers.
Even on a 64bit machine this causes 32bit accesses to a write-
combined memory region.
There are hardware limitations that mean that only
64bit naturally aligned accesses are safe in all cases. Due to being
write-combined memory region two 32bit accesses may be coalesced to
form a 64bit non 64bit aligned access.
Solution was to open-code the memory copy routines using pointers
and to only enable PIO for x86_64 machines.
This bug fix applies to v3.13 and v3.14 stable branches.
Jon Cooper (2):
sfc: use 64-bit writes for PIO.
sfc: Restrict PIO to 64-bit architectures
drivers/net/ethernet/sfc/io.h | 8 ++++++++
drivers/net/ethernet/sfc/tx.c | 24 +++++++++++++++++++-----
2 files changed, 27 insertions(+), 5 deletions(-)
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