From ec9a1d8c13e36440eda0f3c79b8149080e3ab5ba Mon Sep 17 00:00:00 2001 From: Michael Buesch Date: Fri, 27 Mar 2009 22:51:58 +0100 Subject: b43: Poison RX buffers This patch adds poisoning and sanity checking to the RX DMA buffers. This is used for protection against buggy hardware/firmware that raises RX interrupts without doing an actual DMA transfer. This mechanism protects against rare "bad packets" (due to uninitialized skb data) and rare kernel crashes due to uninitialized RX headers. The poison is selected to not match on valid frames and to be cheap for checking. The poison check mechanism _might_ trigger incorrectly, if we are voluntarily receiving frames with bad PLCP headers. However, this is nonfatal, because the chance of such a match is basically zero and in case it happens it just results in dropping the packet. Bad-PLCP RX defaults to off, and you should leave it off unless you want to listen to the latest news broadcasted by your microwave oven. This patch also moves the initialization of the RX-header "length" field in front of the mapping of the DMA buffer. The CPU should not touch the buffer after we mapped it. Cc: stable@kernel.org Reported-by: Francesco Gringoli Signed-off-by: Michael Buesch Signed-off-by: John W. Linville --- drivers/net/wireless/b43/dma.c | 37 +++++++++++++++++++++++++++++++++---- 1 file changed, 33 insertions(+), 4 deletions(-) (limited to 'drivers/net/wireless/b43') diff --git a/drivers/net/wireless/b43/dma.c b/drivers/net/wireless/b43/dma.c index e228c1de6e11..dfa6c72c3bd2 100644 --- a/drivers/net/wireless/b43/dma.c +++ b/drivers/net/wireless/b43/dma.c @@ -555,11 +555,32 @@ address_error: return 1; } +static bool b43_rx_buffer_is_poisoned(struct b43_dmaring *ring, struct sk_buff *skb) +{ + unsigned char *f = skb->data + ring->frameoffset; + + return ((f[0] & f[1] & f[2] & f[3] & f[4] & f[5] & f[6] & f[7]) == 0xFF); +} + +static void b43_poison_rx_buffer(struct b43_dmaring *ring, struct sk_buff *skb) +{ + struct b43_rxhdr_fw4 *rxhdr; + unsigned char *frame; + + /* This poisons the RX buffer to detect DMA failures. */ + + rxhdr = (struct b43_rxhdr_fw4 *)(skb->data); + rxhdr->frame_len = 0; + + B43_WARN_ON(ring->rx_buffersize < ring->frameoffset + sizeof(struct b43_plcp_hdr6) + 2); + frame = skb->data + ring->frameoffset; + memset(frame, 0xFF, sizeof(struct b43_plcp_hdr6) + 2 /* padding */); +} + static int setup_rx_descbuffer(struct b43_dmaring *ring, struct b43_dmadesc_generic *desc, struct b43_dmadesc_meta *meta, gfp_t gfp_flags) { - struct b43_rxhdr_fw4 *rxhdr; dma_addr_t dmaaddr; struct sk_buff *skb; @@ -568,6 +589,7 @@ static int setup_rx_descbuffer(struct b43_dmaring *ring, skb = __dev_alloc_skb(ring->rx_buffersize, gfp_flags); if (unlikely(!skb)) return -ENOMEM; + b43_poison_rx_buffer(ring, skb); dmaaddr = map_descbuffer(ring, skb->data, ring->rx_buffersize, 0); if (b43_dma_mapping_error(ring, dmaaddr, ring->rx_buffersize, 0)) { /* ugh. try to realloc in zone_dma */ @@ -578,6 +600,7 @@ static int setup_rx_descbuffer(struct b43_dmaring *ring, skb = __dev_alloc_skb(ring->rx_buffersize, gfp_flags); if (unlikely(!skb)) return -ENOMEM; + b43_poison_rx_buffer(ring, skb); dmaaddr = map_descbuffer(ring, skb->data, ring->rx_buffersize, 0); if (b43_dma_mapping_error(ring, dmaaddr, ring->rx_buffersize, 0)) { @@ -592,9 +615,6 @@ static int setup_rx_descbuffer(struct b43_dmaring *ring, ring->ops->fill_descriptor(ring, desc, dmaaddr, ring->rx_buffersize, 0, 0, 0); - rxhdr = (struct b43_rxhdr_fw4 *)(skb->data); - rxhdr->frame_len = 0; - return 0; } @@ -1489,6 +1509,15 @@ static void dma_rx(struct b43_dmaring *ring, int *slot) goto drop; } } + if (unlikely(b43_rx_buffer_is_poisoned(ring, skb))) { + /* Something went wrong with the DMA. + * The device did not touch the buffer and did not overwrite the poison. */ + b43dbg(ring->dev->wl, "DMA RX: Dropping poisoned buffer.\n"); + /* recycle the descriptor buffer. */ + sync_descbuffer_for_device(ring, meta->dmaaddr, + ring->rx_buffersize); + goto drop; + } if (unlikely(len > ring->rx_buffersize)) { /* The data did not fit into one descriptor buffer * and is split over multiple buffers. -- cgit v1.2.2 From cf68636a9773aa97915497fe54fa4a51e3f08f3a Mon Sep 17 00:00:00 2001 From: Michael Buesch Date: Sat, 28 Mar 2009 00:41:25 +0100 Subject: b43: Refresh RX poison on buffer recycling The RX buffer poison needs to be refreshed, if we recycle an RX buffer, because it might be (partially) overwritten by some DMA operations. Cc: stable@kernel.org Cc: Francesco Gringoli Signed-off-by: Michael Buesch Signed-off-by: John W. Linville --- drivers/net/wireless/b43/dma.c | 21 +++++++++++---------- 1 file changed, 11 insertions(+), 10 deletions(-) (limited to 'drivers/net/wireless/b43') diff --git a/drivers/net/wireless/b43/dma.c b/drivers/net/wireless/b43/dma.c index dfa6c72c3bd2..eae680b53052 100644 --- a/drivers/net/wireless/b43/dma.c +++ b/drivers/net/wireless/b43/dma.c @@ -1503,20 +1503,16 @@ static void dma_rx(struct b43_dmaring *ring, int *slot) len = le16_to_cpu(rxhdr->frame_len); } while (len == 0 && i++ < 5); if (unlikely(len == 0)) { - /* recycle the descriptor buffer. */ - sync_descbuffer_for_device(ring, meta->dmaaddr, - ring->rx_buffersize); - goto drop; + dmaaddr = meta->dmaaddr; + goto drop_recycle_buffer; } } if (unlikely(b43_rx_buffer_is_poisoned(ring, skb))) { /* Something went wrong with the DMA. * The device did not touch the buffer and did not overwrite the poison. */ b43dbg(ring->dev->wl, "DMA RX: Dropping poisoned buffer.\n"); - /* recycle the descriptor buffer. */ - sync_descbuffer_for_device(ring, meta->dmaaddr, - ring->rx_buffersize); - goto drop; + dmaaddr = meta->dmaaddr; + goto drop_recycle_buffer; } if (unlikely(len > ring->rx_buffersize)) { /* The data did not fit into one descriptor buffer @@ -1530,6 +1526,7 @@ static void dma_rx(struct b43_dmaring *ring, int *slot) while (1) { desc = ops->idx2desc(ring, *slot, &meta); /* recycle the descriptor buffer. */ + b43_poison_rx_buffer(ring, meta->skb); sync_descbuffer_for_device(ring, meta->dmaaddr, ring->rx_buffersize); *slot = next_slot(ring, *slot); @@ -1548,8 +1545,7 @@ static void dma_rx(struct b43_dmaring *ring, int *slot) err = setup_rx_descbuffer(ring, desc, meta, GFP_ATOMIC); if (unlikely(err)) { b43dbg(ring->dev->wl, "DMA RX: setup_rx_descbuffer() failed\n"); - sync_descbuffer_for_device(ring, dmaaddr, ring->rx_buffersize); - goto drop; + goto drop_recycle_buffer; } unmap_descbuffer(ring, dmaaddr, ring->rx_buffersize, 0); @@ -1559,6 +1555,11 @@ static void dma_rx(struct b43_dmaring *ring, int *slot) b43_rx(ring->dev, skb, rxhdr); drop: return; + +drop_recycle_buffer: + /* Poison and recycle the RX buffer. */ + b43_poison_rx_buffer(ring, skb); + sync_descbuffer_for_device(ring, dmaaddr, ring->rx_buffersize); } void b43_dma_rx(struct b43_dmaring *ring) -- cgit v1.2.2 From 591f3dc200abb2100c473248a121ce14bfeeabd6 Mon Sep 17 00:00:00 2001 From: Michael Buesch Date: Tue, 31 Mar 2009 12:27:32 +0200 Subject: b43: Do radio lock assertion in software The assertion of the lock-bit in the hardware register is unreliable, because there are devices with quirks that will randomly set the bit. Do the assertion in software, only. Signed-off-by: Michael Buesch Signed-off-by: John W. Linville --- drivers/net/wireless/b43/main.c | 5 +++++ drivers/net/wireless/b43/phy_common.c | 16 ++++++++++++---- drivers/net/wireless/b43/phy_common.h | 4 +++- 3 files changed, 20 insertions(+), 5 deletions(-) (limited to 'drivers/net/wireless/b43') diff --git a/drivers/net/wireless/b43/main.c b/drivers/net/wireless/b43/main.c index 4896e0831114..79b685e300c7 100644 --- a/drivers/net/wireless/b43/main.c +++ b/drivers/net/wireless/b43/main.c @@ -3974,6 +3974,11 @@ static void setup_struct_phy_for_init(struct b43_wldev *dev, phy->next_txpwr_check_time = jiffies; /* PHY TX errors counter. */ atomic_set(&phy->txerr_cnt, B43_PHY_TX_BADNESS_LIMIT); + +#if B43_DEBUG + phy->phy_locked = 0; + phy->radio_locked = 0; +#endif } static void setup_struct_wldev_for_init(struct b43_wldev *dev) diff --git a/drivers/net/wireless/b43/phy_common.c b/drivers/net/wireless/b43/phy_common.c index 026b61c03fb9..e176b6e0d9cf 100644 --- a/drivers/net/wireless/b43/phy_common.c +++ b/drivers/net/wireless/b43/phy_common.c @@ -131,12 +131,16 @@ void b43_radio_lock(struct b43_wldev *dev) { u32 macctl; +#if B43_DEBUG + B43_WARN_ON(dev->phy.radio_locked); + dev->phy.radio_locked = 1; +#endif + macctl = b43_read32(dev, B43_MMIO_MACCTL); - B43_WARN_ON(macctl & B43_MACCTL_RADIOLOCK); macctl |= B43_MACCTL_RADIOLOCK; b43_write32(dev, B43_MMIO_MACCTL, macctl); - /* Commit the write and wait for the device - * to exit any radio register access. */ + /* Commit the write and wait for the firmware + * to finish any radio register access. */ b43_read32(dev, B43_MMIO_MACCTL); udelay(10); } @@ -145,11 +149,15 @@ void b43_radio_unlock(struct b43_wldev *dev) { u32 macctl; +#if B43_DEBUG + B43_WARN_ON(!dev->phy.radio_locked); + dev->phy.radio_locked = 0; +#endif + /* Commit any write */ b43_read16(dev, B43_MMIO_PHY_VER); /* unlock */ macctl = b43_read32(dev, B43_MMIO_MACCTL); - B43_WARN_ON(!(macctl & B43_MACCTL_RADIOLOCK)); macctl &= ~B43_MACCTL_RADIOLOCK; b43_write32(dev, B43_MMIO_MACCTL, macctl); } diff --git a/drivers/net/wireless/b43/phy_common.h b/drivers/net/wireless/b43/phy_common.h index c9f5430d1d7d..b2d99101947b 100644 --- a/drivers/net/wireless/b43/phy_common.h +++ b/drivers/net/wireless/b43/phy_common.h @@ -245,8 +245,10 @@ struct b43_phy { atomic_t txerr_cnt; #ifdef CONFIG_B43_DEBUG - /* PHY registers locked by b43_phy_lock()? */ + /* PHY registers locked (w.r.t. firmware) */ bool phy_locked; + /* Radio registers locked (w.r.t. firmware) */ + bool radio_locked; #endif /* B43_DEBUG */ }; -- cgit v1.2.2