diff options
| author | Jim Quinlan <jim2101024@gmail.com> | 2013-08-27 16:57:51 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-12-20 07:45:06 -0800 |
| commit | f8d29bed8aecf9b0cfe56c5740855b31c2ea0390 (patch) | |
| tree | 3c21ef93d3b2fa8800bbd43b26e5fb92d8e06c92 /arch | |
| parent | 05bcf8f867f4af11c93395d4a6dd1dd52d8904ea (diff) | |
MIPS: DMA: For BMIPS5000 cores flush region just like non-coherent R10000
commit f86f55d3ad21b21b736bdeb29bee0f0937b77138 upstream.
The BMIPS5000 (Zephyr) processor utilizes instruction speculation. A
stale misprediction address in either the JTB or the CRS may trigger
a prefetch inside a region that is currently being used by a DMA engine,
which is not IO-coherent. This prefetch will fetch a line into the
scache, and that line will soon become stale (ie wrong) during/after the
DMA. Mayhem ensues.
In dma-default.c, the r10000 is handled as a special case in the same way
that we want to handle Zephyr. So we generalize the exception cases into
a function, and include Zephyr as one of the processors that needs this
special care.
Signed-off-by: Jim Quinlan <jim2101024@gmail.com>
Cc: linux-mips@linux-mips.org
Cc: cernekee@gmail.com
Patchwork: https://patchwork.linux-mips.org/patch/5776/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Cc: John Ulvr <julvr@broadcom.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/mips/mm/dma-default.c | 16 |
1 files changed, 10 insertions, 6 deletions
diff --git a/arch/mips/mm/dma-default.c b/arch/mips/mm/dma-default.c index caf92ecb37d..23129d1005d 100644 --- a/arch/mips/mm/dma-default.c +++ b/arch/mips/mm/dma-default.c @@ -50,16 +50,20 @@ static inline struct page *dma_addr_to_page(struct device *dev, } /* + * The affected CPUs below in 'cpu_needs_post_dma_flush()' can + * speculatively fill random cachelines with stale data at any time, + * requiring an extra flush post-DMA. + * * Warning on the terminology - Linux calls an uncached area coherent; * MIPS terminology calls memory areas with hardware maintained coherency * coherent. */ - -static inline int cpu_is_noncoherent_r10000(struct device *dev) +static inline int cpu_needs_post_dma_flush(struct device *dev) { return !plat_device_is_coherent(dev) && (current_cpu_type() == CPU_R10000 || - current_cpu_type() == CPU_R12000); + current_cpu_type() == CPU_R12000 || + current_cpu_type() == CPU_BMIPS5000); } static gfp_t massage_gfp_flags(const struct device *dev, gfp_t gfp) @@ -230,7 +234,7 @@ static inline void __dma_sync(struct page *page, static void mips_dma_unmap_page(struct device *dev, dma_addr_t dma_addr, size_t size, enum dma_data_direction direction, struct dma_attrs *attrs) { - if (cpu_is_noncoherent_r10000(dev)) + if (cpu_needs_post_dma_flush(dev)) __dma_sync(dma_addr_to_page(dev, dma_addr), dma_addr & ~PAGE_MASK, size, direction); @@ -281,7 +285,7 @@ static void mips_dma_unmap_sg(struct device *dev, struct scatterlist *sg, static void mips_dma_sync_single_for_cpu(struct device *dev, dma_addr_t dma_handle, size_t size, enum dma_data_direction direction) { - if (cpu_is_noncoherent_r10000(dev)) + if (cpu_needs_post_dma_flush(dev)) __dma_sync(dma_addr_to_page(dev, dma_handle), dma_handle & ~PAGE_MASK, size, direction); } @@ -302,7 +306,7 @@ static void mips_dma_sync_sg_for_cpu(struct device *dev, /* Make sure that gcc doesn't leave the empty loop body. */ for (i = 0; i < nelems; i++, sg++) { - if (cpu_is_noncoherent_r10000(dev)) + if (cpu_needs_post_dma_flush(dev)) __dma_sync(sg_page(sg), sg->offset, sg->length, direction); } |