From 4a54d16f615f41489b2ecbc940f6eb2618ddafd6 Mon Sep 17 00:00:00 2001
From: Christoph Hellwig <hch@lst.de>
Date: Mon, 29 Apr 2019 09:16:42 -0500
Subject: [PATCH] dma-mapping: truncate dma masks to what dma_addr_t can hold
The dma masks in struct device are always 64-bits wide. But for builds
using a 32-bit dma_addr_t we need to ensure we don't store an
unsupportable value. Before Linux 5.0 this was handled at least by
the ARM dma mapping code by never allowing to set a larger dma_mask,
but these days we allow the driver to just set the largest supported
value and never fall back to a smaller one. Ensure this always works
by truncating the value.
Fixes: 9eb9e96e97b3 ("Documentation/DMA-API-HOWTO: update dma_mask sections")
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
kernel/dma/mapping.c | 12 ++++++++++++
1 file changed, 12 insertions(+)
diff --git a/kernel/dma/mapping.c b/kernel/dma/mapping.c
index f7afdadb6770b..1f628e7ac7097 100644
--- a/kernel/dma/mapping.c
+++ b/kernel/dma/mapping.c
@@ -317,6 +317,12 @@ void arch_dma_set_mask(struct device *dev, u64 mask);
int dma_set_mask(struct device *dev, u64 mask)
{
+ /*
+ * Truncate the mask to the actually supported dma_addr_t width to
+ * avoid generating unsupportable addresses.
+ */
+ mask = (dma_addr_t)mask;
+
if (!dev->dma_mask || !dma_supported(dev, mask))
return -EIO;
@@ -330,6 +336,12 @@ EXPORT_SYMBOL(dma_set_mask);
#ifndef CONFIG_ARCH_HAS_DMA_SET_COHERENT_MASK
int dma_set_coherent_mask(struct device *dev, u64 mask)
{
+ /*
+ * Truncate the mask to the actually supported dma_addr_t width to
+ * avoid generating unsupportable addresses.
+ */
+ mask = (dma_addr_t)mask;
+
if (!dma_supported(dev, mask))
return -EIO;
--
2.30.2