lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  PHC 
Open Source and information security mailing list archives
 
Hash Suite for Android: free password hash cracker in your pocket
[<prev] [next>] [thread-next>] [day] [month] [year] [list]
Date:	Fri,  9 Jan 2015 16:56:03 +0000
From:	Robin Murphy <robin.murphy@....com>
To:	will.deacon@....com, arnd@...db.de, m.szyprowski@...sung.com,
	bhelgaas@...gle.com, joro@...tes.org, gregkh@...uxfoundation.org
Cc:	iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org
Subject: [PATCH RESEND] dma-mapping: tidy up dma_parms default handling

Many DMA controllers and other devices set max_segment_size to
indicate their scatter-gather capability, but have no interest in
segment_boundary_mask. However, the existence of a dma_parms structure
precludes the use of any default value, leaving them as zeros (assuming
a properly kzalloc'ed structure). If a well-behaved IOMMU (or SWIOTLB)
then tries to respect this by ensuring a mapped segment does not cross
a zero-byte boundary, hilarity ensues.

Since zero is a nonsensical value for either parameter, treat it as an
indicator for "default", as might be expected. In the process, clean up
a bit by replacing the bare constants with slightly more meaningful
macros and removing the superfluous "else" statements.

Signed-off-by: Robin Murphy <robin.murphy@....com>
---

Hi, various maintainers from Git logs ;)

This one's a bit tricky to find a home for - I think technically it's 
probably an IOMMU patch, but then the long-underlying problem doesn't
seem to have blown up anything until arm64, and my motivation is to
make bits of Juno work, which seems to nudge it towards arm64/arm-soc
territory. Could anyone suggest which tree is most appropriate?

Thanks,
Robin.

 include/linux/dma-mapping.h | 17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index c3007cb..99ba736 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h
@@ -141,7 +141,9 @@ static inline void arch_teardown_dma_ops(struct device *dev) { }
 
 static inline unsigned int dma_get_max_seg_size(struct device *dev)
 {
-	return dev->dma_parms ? dev->dma_parms->max_segment_size : 65536;
+	if (dev->dma_parms && dev->dma_parms->max_segment_size)
+		return dev->dma_parms->max_segment_size;
+	return SZ_64K;
 }
 
 static inline unsigned int dma_set_max_seg_size(struct device *dev,
@@ -150,14 +152,15 @@ static inline unsigned int dma_set_max_seg_size(struct device *dev,
 	if (dev->dma_parms) {
 		dev->dma_parms->max_segment_size = size;
 		return 0;
-	} else
-		return -EIO;
+	}
+	return -EIO;
 }
 
 static inline unsigned long dma_get_seg_boundary(struct device *dev)
 {
-	return dev->dma_parms ?
-		dev->dma_parms->segment_boundary_mask : 0xffffffff;
+	if (dev->dma_parms && dev->dma_parms->segment_boundary_mask)
+		return dev->dma_parms->segment_boundary_mask;
+	return DMA_BIT_MASK(32);
 }
 
 static inline int dma_set_seg_boundary(struct device *dev, unsigned long mask)
@@ -165,8 +168,8 @@ static inline int dma_set_seg_boundary(struct device *dev, unsigned long mask)
 	if (dev->dma_parms) {
 		dev->dma_parms->segment_boundary_mask = mask;
 		return 0;
-	} else
-		return -EIO;
+	}
+	return -EIO;
 }
 
 #ifndef dma_max_pfn
-- 
1.9.1


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Powered by blists - more mailing lists