From: Arnd Bergmann <arnd@arndb.de>
To: Christoph Hellwig <hch@lst.de>,
Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Juergen Gross <jgross@suse.com>,
Stefano Stabellini <sstabellini@kernel.org>,
Arnd Bergmann <arnd@arndb.de>,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
linux-kernel@vger.kernel.org, Mike Rapoport <rppt@linux.ibm.com>,
iommu@lists.linux-foundation.org, Joerg Roedel <jroedel@suse.de>,
Jesper Dangaard Brouer <brouer@redhat.com>,
xen-devel@lists.xenproject.org,
Boris Ostrovsky <boris.ostrovsky@oracle.com>,
Robin Murphy <robin.murphy@arm.com>,
Andrew Morton <akpm@linux-foundation.org>
Subject: [Xen-devel] [PATCH] swiotlb: fix phys_addr_t overflow warning
Date: Mon, 17 Jun 2019 15:28:43 +0200 [thread overview]
Message-ID: <20190617132946.2817440-1-arnd@arndb.de> (raw)
On architectures that have a larger dma_addr_t than phys_addr_t,
the swiotlb_tbl_map_single() function truncates its return code
in the failure path, making it impossible to identify the error
later, as we compare to the original value:
kernel/dma/swiotlb.c:551:9: error: implicit conversion from 'dma_addr_t' (aka 'unsigned long long') to 'phys_addr_t' (aka 'unsigned int') changes value from 18446744073709551615 to 4294967295 [-Werror,-Wconstant-conversion]
return DMA_MAPPING_ERROR;
Use an explicit typecast here to convert it to the narrower type,
and use the same expression in the error handling later.
Fixes: b907e20508d0 ("swiotlb: remove SWIOTLB_MAP_ERROR")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
I still think that reverting the original commit would have
provided clearer semantics for this corner case, but at least
this patch restores the correct behavior.
---
drivers/xen/swiotlb-xen.c | 2 +-
kernel/dma/swiotlb.c | 4 ++--
2 files changed, 3 insertions(+), 3 deletions(-)
diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
index d53f3493a6b9..cfbe46785a3b 100644
--- a/drivers/xen/swiotlb-xen.c
+++ b/drivers/xen/swiotlb-xen.c
@@ -402,7 +402,7 @@ static dma_addr_t xen_swiotlb_map_page(struct device *dev, struct page *page,
map = swiotlb_tbl_map_single(dev, start_dma_addr, phys, size, dir,
attrs);
- if (map == DMA_MAPPING_ERROR)
+ if (map == (phys_addr_t)DMA_MAPPING_ERROR)
return DMA_MAPPING_ERROR;
dev_addr = xen_phys_to_bus(map);
diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
index e906ef2e6315..a3be651973ad 100644
--- a/kernel/dma/swiotlb.c
+++ b/kernel/dma/swiotlb.c
@@ -548,7 +548,7 @@ phys_addr_t swiotlb_tbl_map_single(struct device *hwdev,
if (!(attrs & DMA_ATTR_NO_WARN) && printk_ratelimit())
dev_warn(hwdev, "swiotlb buffer is full (sz: %zd bytes), total %lu (slots), used %lu (slots)\n",
size, io_tlb_nslabs, tmp_io_tlb_used);
- return DMA_MAPPING_ERROR;
+ return (phys_addr_t)DMA_MAPPING_ERROR;
found:
io_tlb_used += nslots;
spin_unlock_irqrestore(&io_tlb_lock, flags);
@@ -666,7 +666,7 @@ bool swiotlb_map(struct device *dev, phys_addr_t *phys, dma_addr_t *dma_addr,
/* Oh well, have to allocate and map a bounce buffer. */
*phys = swiotlb_tbl_map_single(dev, __phys_to_dma(dev, io_tlb_start),
*phys, size, dir, attrs);
- if (*phys == DMA_MAPPING_ERROR)
+ if (*phys == (phys_addr_t)DMA_MAPPING_ERROR)
return false;
/* Ensure that the address returned is DMA'ble */
--
2.20.0
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next reply other threads:[~2019-06-17 13:30 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-17 13:28 Arnd Bergmann [this message]
2019-06-17 16:13 ` [Xen-devel] [PATCH] swiotlb: fix phys_addr_t overflow warning Stefano Stabellini
2019-06-19 14:28 ` Konrad Rzeszutek Wilk
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