[PATCH 5/5] tg3: Fix data corruption on 5725 with TSO

[Stefan Bader]

From: Michael Chan <mchan at broadcom.com>

The 5725 family of devices (asic rev 5762), corrupts TSO packets where
the buffer is within MSS bytes of a 4G boundary (4G, 8G etc.). Detect
this condition and trigger the workaround path.

Cc: <stable at vger.kernel.org>
Signed-off-by: Michael Chan <mchan at broadcom.com>
Signed-off-by: Nithin Nayak Sujir <nsujir at broadcom.com>
Signed-off-by: David S. Miller <davem at davemloft.net>

BugLink: http://bugs.launchpad.net/bugs/1178899

(backported from commit 0f0d15100a8ac875bdd408324c473e16d73d3557 upstream)
Signed-off-by: Stefan Bader <stefan.bader at canonical.com>
---
 drivers/net/ethernet/broadcom/tg3.c |   17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/drivers/net/ethernet/broadcom/tg3.c b/drivers/net/ethernet/broadcom/tg3.c
index bbf2650..5cda44c 100644
--- a/drivers/net/ethernet/broadcom/tg3.c
+++ b/drivers/net/ethernet/broadcom/tg3.c
@@ -7003,6 +7003,20 @@ static inline int tg3_4g_overflow_test(dma_addr_t mapping, int len)
 	return (base > 0xffffdcc0) && (base + len + 8 < base);
 }
 
+/* Test for TSO DMA buffers that cross into regions which are within MSS bytes
+ * of any 4GB boundaries: 4G, 8G, etc
+ */
+static inline int tg3_4g_tso_overflow_test(struct tg3 *tp, dma_addr_t mapping,
+					   u32 len, u32 mss)
+{
+	if (GET_ASIC_REV(tp->pci_chip_rev_id) == ASIC_REV_5762 && mss) {
+		u32 base = (u32) mapping & 0xffffffff;
+
+		return ((base + len + (mss & 0x3fff)) < base);
+	}
+	return 0;
+}
+
 /* Test for DMA addresses > 40-bit */
 static inline int tg3_40bit_overflow_test(struct tg3 *tp, dma_addr_t mapping,
 					  int len)
@@ -7039,6 +7053,9 @@ static bool tg3_tx_frag_set(struct tg3_napi *tnapi, u32 *entry, u32 *budget,
 	if (tg3_4g_overflow_test(map, len))
 		hwbug = true;
 
+	if (tg3_4g_tso_overflow_test(tp, map, len, mss))
+		hwbug = true;
+
 	if (tg3_40bit_overflow_test(tp, map, len))
 		hwbug = true;
 
-- 
1.7.9.5