net: change illegal_highdma to use dma_mask
Robert Hancock pointed out two problems about NETIF_F_HIGHDMA:
-Many drivers only set the flag when they detect they can use 64-bit DMA,
since otherwise they could receive DMA addresses that they can't handle
(which on platforms without IOMMU/SWIOTLB support is fatal). This means that if
64-bit support isn't available, even buffers located below 4GB will get copied
unnecessarily.
-Some drivers set the flag even though they can't actually handle 64-bit DMA,
which would mean that on platforms without IOMMU/SWIOTLB they would get a DMA
mapping error if the memory they received happened to be located above 4GB.
http://lkml.org/lkml/2010/3/3/530
We can use the dma_mask if we need bouncing or not here. Then we can
safely fix drivers that misuse NETIF_F_HIGHDMA.
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/core/dev.c b/net/core/dev.c
index 427cd53..e19cdae 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -129,6 +129,7 @@
#include <linux/jhash.h>
#include <linux/random.h>
#include <trace/events/napi.h>
+#include <linux/pci.h>
#include "net-sysfs.h"
@@ -1804,14 +1805,21 @@
{
#ifdef CONFIG_HIGHMEM
int i;
+ if (!(dev->features & NETIF_F_HIGHDMA)) {
+ for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
+ if (PageHighMem(skb_shinfo(skb)->frags[i].page))
+ return 1;
+ }
- if (dev->features & NETIF_F_HIGHDMA)
- return 0;
+ if (PCI_DMA_BUS_IS_PHYS) {
+ struct device *pdev = dev->dev.parent;
- for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
- if (PageHighMem(skb_shinfo(skb)->frags[i].page))
- return 1;
-
+ for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
+ dma_addr_t addr = page_to_phys(skb_shinfo(skb)->frags[i].page);
+ if (!pdev->dma_mask || addr + PAGE_SIZE - 1 > *pdev->dma_mask)
+ return 1;
+ }
+ }
#endif
return 0;
}