* [PATCH] arm64: dma-mapping: Fix FORCE_CONTIGUOUS buffer clearing
@ 2018-12-10 19:33 Robin Murphy
2018-12-10 19:36 ` Will Deacon
2018-12-12 7:31 ` Chintan Pandya
0 siblings, 2 replies; 5+ messages in thread
From: Robin Murphy @ 2018-12-10 19:33 UTC (permalink / raw)
To: will.deacon, catalin.marinas; +Cc: hch, linux-arm-kernel, m.szyprowski
We need to invalidate the caches *before* clearing the buffer via the
non-cacheable alias, else in the worst case __dma_flush_area() may
write back dirty lines over the top of our nice new zeros.
Fixes: dd65a941f6ba ("arm64: dma-mapping: clear buffers allocated with FORCE_CONTIGUOUS flag")
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
---
arch/arm64/mm/dma-mapping.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c
index a3ac26284845..a53704406099 100644
--- a/arch/arm64/mm/dma-mapping.c
+++ b/arch/arm64/mm/dma-mapping.c
@@ -429,9 +429,9 @@ static void *__iommu_alloc_attrs(struct device *dev, size_t size,
prot,
__builtin_return_address(0));
if (addr) {
- memset(addr, 0, size);
if (!coherent)
__dma_flush_area(page_to_virt(page), iosize);
+ memset(addr, 0, size);
} else {
iommu_dma_unmap_page(dev, *handle, iosize, 0, attrs);
dma_release_from_contiguous(dev, page,
--
2.19.1.dirty
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^ permalink raw reply related [flat|nested] 5+ messages in thread* Re: [PATCH] arm64: dma-mapping: Fix FORCE_CONTIGUOUS buffer clearing 2018-12-10 19:33 [PATCH] arm64: dma-mapping: Fix FORCE_CONTIGUOUS buffer clearing Robin Murphy @ 2018-12-10 19:36 ` Will Deacon 2018-12-11 11:55 ` Catalin Marinas 2018-12-12 7:31 ` Chintan Pandya 1 sibling, 1 reply; 5+ messages in thread From: Will Deacon @ 2018-12-10 19:36 UTC (permalink / raw) To: Robin Murphy; +Cc: catalin.marinas, hch, linux-arm-kernel, m.szyprowski On Mon, Dec 10, 2018 at 07:33:31PM +0000, Robin Murphy wrote: > We need to invalidate the caches *before* clearing the buffer via the > non-cacheable alias, else in the worst case __dma_flush_area() may > write back dirty lines over the top of our nice new zeros. > > Fixes: dd65a941f6ba ("arm64: dma-mapping: clear buffers allocated with FORCE_CONTIGUOUS flag") > Signed-off-by: Robin Murphy <robin.murphy@arm.com> > --- > arch/arm64/mm/dma-mapping.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c > index a3ac26284845..a53704406099 100644 > --- a/arch/arm64/mm/dma-mapping.c > +++ b/arch/arm64/mm/dma-mapping.c > @@ -429,9 +429,9 @@ static void *__iommu_alloc_attrs(struct device *dev, size_t size, > prot, > __builtin_return_address(0)); > if (addr) { > - memset(addr, 0, size); > if (!coherent) > __dma_flush_area(page_to_virt(page), iosize); > + memset(addr, 0, size); > } else { > iommu_dma_unmap_page(dev, *handle, iosize, 0, attrs); > dma_release_from_contiguous(dev, page, Oh crikey, well spotted! Acked-by: Will Deacon <will.deacon@arm.com> Catalin, please take this with a Cc stable. Will _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] arm64: dma-mapping: Fix FORCE_CONTIGUOUS buffer clearing 2018-12-10 19:36 ` Will Deacon @ 2018-12-11 11:55 ` Catalin Marinas 0 siblings, 0 replies; 5+ messages in thread From: Catalin Marinas @ 2018-12-11 11:55 UTC (permalink / raw) To: Will Deacon; +Cc: Robin Murphy, hch, linux-arm-kernel, m.szyprowski On Mon, Dec 10, 2018 at 07:36:18PM +0000, Will Deacon wrote: > On Mon, Dec 10, 2018 at 07:33:31PM +0000, Robin Murphy wrote: > > We need to invalidate the caches *before* clearing the buffer via the > > non-cacheable alias, else in the worst case __dma_flush_area() may > > write back dirty lines over the top of our nice new zeros. > > > > Fixes: dd65a941f6ba ("arm64: dma-mapping: clear buffers allocated with FORCE_CONTIGUOUS flag") > > Signed-off-by: Robin Murphy <robin.murphy@arm.com> > > --- > > arch/arm64/mm/dma-mapping.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c > > index a3ac26284845..a53704406099 100644 > > --- a/arch/arm64/mm/dma-mapping.c > > +++ b/arch/arm64/mm/dma-mapping.c > > @@ -429,9 +429,9 @@ static void *__iommu_alloc_attrs(struct device *dev, size_t size, > > prot, > > __builtin_return_address(0)); > > if (addr) { > > - memset(addr, 0, size); > > if (!coherent) > > __dma_flush_area(page_to_virt(page), iosize); > > + memset(addr, 0, size); > > } else { > > iommu_dma_unmap_page(dev, *handle, iosize, 0, attrs); > > dma_release_from_contiguous(dev, page, > > Oh crikey, well spotted! > > Acked-by: Will Deacon <will.deacon@arm.com> > > Catalin, please take this with a Cc stable. Queued. Thanks. -- Catalin _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] arm64: dma-mapping: Fix FORCE_CONTIGUOUS buffer clearing 2018-12-10 19:33 [PATCH] arm64: dma-mapping: Fix FORCE_CONTIGUOUS buffer clearing Robin Murphy 2018-12-10 19:36 ` Will Deacon @ 2018-12-12 7:31 ` Chintan Pandya 2018-12-12 7:37 ` Christoph Hellwig 1 sibling, 1 reply; 5+ messages in thread From: Chintan Pandya @ 2018-12-12 7:31 UTC (permalink / raw) To: Robin Murphy, will.deacon, catalin.marinas Cc: hch, linux-arm-kernel, m.szyprowski On 12/11/2018 1:03 AM, Robin Murphy wrote: > We need to invalidate the caches *before* clearing the buffer via the > non-cacheable alias, else in the worst case __dma_flush_area() may > write back dirty lines over the top of our nice new zeros. > > Fixes: dd65a941f6ba ("arm64: dma-mapping: clear buffers allocated with FORCE_CONTIGUOUS flag") > Signed-off-by: Robin Murphy <robin.murphy@arm.com> > --- > arch/arm64/mm/dma-mapping.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c > index a3ac26284845..a53704406099 100644 > --- a/arch/arm64/mm/dma-mapping.c > +++ b/arch/arm64/mm/dma-mapping.c > @@ -429,9 +429,9 @@ static void *__iommu_alloc_attrs(struct device *dev, size_t size, > prot, > __builtin_return_address(0)); > if (addr) { > - memset(addr, 0, size); > if (!coherent) > __dma_flush_area(page_to_virt(page), iosize); > + memset(addr, 0, size); For coherent case, we still skip flushing/invalidating dirty kernel mappings. Isn't it a problem ? Shouldn't it be, --- a/arch/arm64/mm/dma-mapping.c +++ b/arch/arm64/mm/dma-mapping.c @@ -774,9 +774,8 @@ static void *__iommu_alloc_attrs(struct device *dev, size_t size, prot, __builtin_return_address(0)); if (addr) { + __dma_flush_area(page_to_virt(page), iosize); memset(addr, 0, size); - if (!coherent) - __dma_flush_area(page_to_virt(page), iosize); } else { iommu_dma_unmap_page(dev, *handle, iosize, 0, attrs); dma_release_from_contiguous(dev, page, > } else { > iommu_dma_unmap_page(dev, *handle, iosize, 0, attrs); > dma_release_from_contiguous(dev, page, > Chintan -- Qualcomm India Private Limited, on behalf of Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] arm64: dma-mapping: Fix FORCE_CONTIGUOUS buffer clearing 2018-12-12 7:31 ` Chintan Pandya @ 2018-12-12 7:37 ` Christoph Hellwig 0 siblings, 0 replies; 5+ messages in thread From: Christoph Hellwig @ 2018-12-12 7:37 UTC (permalink / raw) To: Chintan Pandya Cc: catalin.marinas, will.deacon, Robin Murphy, hch, linux-arm-kernel, m.szyprowski On Wed, Dec 12, 2018 at 01:01:41PM +0530, Chintan Pandya wrote: >> if (addr) { >> - memset(addr, 0, size); >> if (!coherent) >> __dma_flush_area(page_to_virt(page), iosize); >> + memset(addr, 0, size); > > For coherent case, we still skip flushing/invalidating dirty kernel > mappings. Isn't it a problem ? For the dma coherent case there is no need to writeback and/or invalidate the kernel mapping. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel ^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2018-12-12 7:37 UTC | newest] Thread overview: 5+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2018-12-10 19:33 [PATCH] arm64: dma-mapping: Fix FORCE_CONTIGUOUS buffer clearing Robin Murphy 2018-12-10 19:36 ` Will Deacon 2018-12-11 11:55 ` Catalin Marinas 2018-12-12 7:31 ` Chintan Pandya 2018-12-12 7:37 ` Christoph Hellwig
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