* [PATCH] dma-debug: don't enforce dma mapping check on noncoherent allocations @ 2025-08-28 8:17 ` Baochen Qiang 2025-09-02 8:41 ` Marek Szyprowski 0 siblings, 1 reply; 2+ messages in thread From: Baochen Qiang @ 2025-08-28 8:17 UTC (permalink / raw) To: Marek Szyprowski, Robin Murphy, Thomas Bogendoerfer Cc: iommu, linux-kernel, Baochen Qiang As discussed in [1], there is no need to enforce dma mapping check on noncoherent allocations, a simple test on the returned CPU address is good enough. Add a new pair of debug helpers and use them for noncoherent alloc/free to fix this issue. Fixes: efa70f2fdc84 ("dma-mapping: add a new dma_alloc_pages API") Link: https://lore.kernel.org/all/ff6c1fe6-820f-4e58-8395-df06aa91706c@oss.qualcomm.com # 1 Signed-off-by: Baochen Qiang <baochen.qiang@oss.qualcomm.com> --- kernel/dma/debug.c | 48 +++++++++++++++++++++++++++++++++++++++++++++++- kernel/dma/debug.h | 20 ++++++++++++++++++++ kernel/dma/mapping.c | 4 ++-- 3 files changed, 69 insertions(+), 3 deletions(-) diff --git a/kernel/dma/debug.c b/kernel/dma/debug.c index e43c6de2bce4e7d3e58f8d9601a7637d8f6da767..b82399437db03116a396c7d1cebd16b2e1af98c3 100644 --- a/kernel/dma/debug.c +++ b/kernel/dma/debug.c @@ -39,6 +39,7 @@ enum { dma_debug_sg, dma_debug_coherent, dma_debug_resource, + dma_debug_noncoherent, }; enum map_err_types { @@ -141,6 +142,7 @@ static const char *type2name[] = { [dma_debug_sg] = "scatter-gather", [dma_debug_coherent] = "coherent", [dma_debug_resource] = "resource", + [dma_debug_noncoherent] = "noncoherent", }; static const char *dir2name[] = { @@ -993,7 +995,8 @@ static void check_unmap(struct dma_debug_entry *ref) "[mapped as %s] [unmapped as %s]\n", ref->dev_addr, ref->size, type2name[entry->type], type2name[ref->type]); - } else if (entry->type == dma_debug_coherent && + } else if ((entry->type == dma_debug_coherent || + entry->type == dma_debug_noncoherent) && ref->paddr != entry->paddr) { err_printk(ref->dev, entry, "device driver frees " "DMA memory with different CPU address " @@ -1581,6 +1584,49 @@ void debug_dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg, } } +void debug_dma_alloc_pages(struct device *dev, struct page *page, + size_t size, int direction, + dma_addr_t dma_addr, + unsigned long attrs) +{ + struct dma_debug_entry *entry; + + if (unlikely(dma_debug_disabled())) + return; + + entry = dma_entry_alloc(); + if (!entry) + return; + + entry->type = dma_debug_noncoherent; + entry->dev = dev; + entry->paddr = page_to_phys(page); + entry->size = size; + entry->dev_addr = dma_addr; + entry->direction = direction; + + add_dma_entry(entry, attrs); +} + +void debug_dma_free_pages(struct device *dev, struct page *page, + size_t size, int direction, + dma_addr_t dma_addr) +{ + struct dma_debug_entry ref = { + .type = dma_debug_noncoherent, + .dev = dev, + .paddr = page_to_phys(page), + .dev_addr = dma_addr, + .size = size, + .direction = direction, + }; + + if (unlikely(dma_debug_disabled())) + return; + + check_unmap(&ref); +} + static int __init dma_debug_driver_setup(char *str) { int i; diff --git a/kernel/dma/debug.h b/kernel/dma/debug.h index f525197d3cae605aa7e0499eb2ca6f1ae134ec93..48757ca13f31403f58090e1015de828893b8f94f 100644 --- a/kernel/dma/debug.h +++ b/kernel/dma/debug.h @@ -54,6 +54,13 @@ extern void debug_dma_sync_sg_for_cpu(struct device *dev, extern void debug_dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg, int nelems, int direction); +extern void debug_dma_alloc_pages(struct device *dev, struct page *page, + size_t size, int direction, + dma_addr_t dma_addr, + unsigned long attrs); +extern void debug_dma_free_pages(struct device *dev, struct page *page, + size_t size, int direction, + dma_addr_t dma_addr); #else /* CONFIG_DMA_API_DEBUG */ static inline void debug_dma_map_page(struct device *dev, struct page *page, size_t offset, size_t size, @@ -126,5 +133,18 @@ static inline void debug_dma_sync_sg_for_device(struct device *dev, int nelems, int direction) { } + +static inline void debug_dma_alloc_pages(struct device *dev, struct page *page, + size_t size, int direction, + dma_addr_t dma_addr, + unsigned long attrs) +{ +} + +static inline void debug_dma_free_pages(struct device *dev, struct page *page, + size_t size, int direction, + dma_addr_t dma_addr) +{ +} #endif /* CONFIG_DMA_API_DEBUG */ #endif /* _KERNEL_DMA_DEBUG_H */ diff --git a/kernel/dma/mapping.c b/kernel/dma/mapping.c index 107e4a4d251df65fb86a1d7302261c31138061b7..56de28a3b1799f7c18f7e3f8e5ecd438c5748677 100644 --- a/kernel/dma/mapping.c +++ b/kernel/dma/mapping.c @@ -712,7 +712,7 @@ struct page *dma_alloc_pages(struct device *dev, size_t size, if (page) { trace_dma_alloc_pages(dev, page_to_virt(page), *dma_handle, size, dir, gfp, 0); - debug_dma_map_page(dev, page, 0, size, dir, *dma_handle, 0); + debug_dma_alloc_pages(dev, page, size, dir, *dma_handle, 0); } else { trace_dma_alloc_pages(dev, NULL, 0, size, dir, gfp, 0); } @@ -738,7 +738,7 @@ void dma_free_pages(struct device *dev, size_t size, struct page *page, dma_addr_t dma_handle, enum dma_data_direction dir) { trace_dma_free_pages(dev, page_to_virt(page), dma_handle, size, dir, 0); - debug_dma_unmap_page(dev, dma_handle, size, dir); + debug_dma_free_pages(dev, page, size, dir, dma_handle); __dma_free_pages(dev, size, page, dma_handle, dir); } EXPORT_SYMBOL_GPL(dma_free_pages); --- base-commit: 95bf875b89b48a95a82aca922eeaf19d52543028 change-id: 20250828-dma-debug-fix-noncoherent-dma-check-8e6915d58494 Best regards, -- Baochen Qiang <baochen.qiang@oss.qualcomm.com> ^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [PATCH] dma-debug: don't enforce dma mapping check on noncoherent allocations 2025-08-28 8:17 ` [PATCH] dma-debug: don't enforce dma mapping check on noncoherent allocations Baochen Qiang @ 2025-09-02 8:41 ` Marek Szyprowski 0 siblings, 0 replies; 2+ messages in thread From: Marek Szyprowski @ 2025-09-02 8:41 UTC (permalink / raw) To: Baochen Qiang, Robin Murphy, Thomas Bogendoerfer; +Cc: iommu, linux-kernel On 28.08.2025 10:17, Baochen Qiang wrote: > As discussed in [1], there is no need to enforce dma mapping check on > noncoherent allocations, a simple test on the returned CPU address is > good enough. > > Add a new pair of debug helpers and use them for noncoherent alloc/free > to fix this issue. > > Fixes: efa70f2fdc84 ("dma-mapping: add a new dma_alloc_pages API") > Link: https://lore.kernel.org/all/ff6c1fe6-820f-4e58-8395-df06aa91706c@oss.qualcomm.com # 1 > Signed-off-by: Baochen Qiang <baochen.qiang@oss.qualcomm.com> Thanks, applied to dma-mapping-fixes branch. > --- > kernel/dma/debug.c | 48 +++++++++++++++++++++++++++++++++++++++++++++++- > kernel/dma/debug.h | 20 ++++++++++++++++++++ > kernel/dma/mapping.c | 4 ++-- > 3 files changed, 69 insertions(+), 3 deletions(-) > > diff --git a/kernel/dma/debug.c b/kernel/dma/debug.c > index e43c6de2bce4e7d3e58f8d9601a7637d8f6da767..b82399437db03116a396c7d1cebd16b2e1af98c3 100644 > --- a/kernel/dma/debug.c > +++ b/kernel/dma/debug.c > @@ -39,6 +39,7 @@ enum { > dma_debug_sg, > dma_debug_coherent, > dma_debug_resource, > + dma_debug_noncoherent, > }; > > enum map_err_types { > @@ -141,6 +142,7 @@ static const char *type2name[] = { > [dma_debug_sg] = "scatter-gather", > [dma_debug_coherent] = "coherent", > [dma_debug_resource] = "resource", > + [dma_debug_noncoherent] = "noncoherent", > }; > > static const char *dir2name[] = { > @@ -993,7 +995,8 @@ static void check_unmap(struct dma_debug_entry *ref) > "[mapped as %s] [unmapped as %s]\n", > ref->dev_addr, ref->size, > type2name[entry->type], type2name[ref->type]); > - } else if (entry->type == dma_debug_coherent && > + } else if ((entry->type == dma_debug_coherent || > + entry->type == dma_debug_noncoherent) && > ref->paddr != entry->paddr) { > err_printk(ref->dev, entry, "device driver frees " > "DMA memory with different CPU address " > @@ -1581,6 +1584,49 @@ void debug_dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg, > } > } > > +void debug_dma_alloc_pages(struct device *dev, struct page *page, > + size_t size, int direction, > + dma_addr_t dma_addr, > + unsigned long attrs) > +{ > + struct dma_debug_entry *entry; > + > + if (unlikely(dma_debug_disabled())) > + return; > + > + entry = dma_entry_alloc(); > + if (!entry) > + return; > + > + entry->type = dma_debug_noncoherent; > + entry->dev = dev; > + entry->paddr = page_to_phys(page); > + entry->size = size; > + entry->dev_addr = dma_addr; > + entry->direction = direction; > + > + add_dma_entry(entry, attrs); > +} > + > +void debug_dma_free_pages(struct device *dev, struct page *page, > + size_t size, int direction, > + dma_addr_t dma_addr) > +{ > + struct dma_debug_entry ref = { > + .type = dma_debug_noncoherent, > + .dev = dev, > + .paddr = page_to_phys(page), > + .dev_addr = dma_addr, > + .size = size, > + .direction = direction, > + }; > + > + if (unlikely(dma_debug_disabled())) > + return; > + > + check_unmap(&ref); > +} > + > static int __init dma_debug_driver_setup(char *str) > { > int i; > diff --git a/kernel/dma/debug.h b/kernel/dma/debug.h > index f525197d3cae605aa7e0499eb2ca6f1ae134ec93..48757ca13f31403f58090e1015de828893b8f94f 100644 > --- a/kernel/dma/debug.h > +++ b/kernel/dma/debug.h > @@ -54,6 +54,13 @@ extern void debug_dma_sync_sg_for_cpu(struct device *dev, > extern void debug_dma_sync_sg_for_device(struct device *dev, > struct scatterlist *sg, > int nelems, int direction); > +extern void debug_dma_alloc_pages(struct device *dev, struct page *page, > + size_t size, int direction, > + dma_addr_t dma_addr, > + unsigned long attrs); > +extern void debug_dma_free_pages(struct device *dev, struct page *page, > + size_t size, int direction, > + dma_addr_t dma_addr); > #else /* CONFIG_DMA_API_DEBUG */ > static inline void debug_dma_map_page(struct device *dev, struct page *page, > size_t offset, size_t size, > @@ -126,5 +133,18 @@ static inline void debug_dma_sync_sg_for_device(struct device *dev, > int nelems, int direction) > { > } > + > +static inline void debug_dma_alloc_pages(struct device *dev, struct page *page, > + size_t size, int direction, > + dma_addr_t dma_addr, > + unsigned long attrs) > +{ > +} > + > +static inline void debug_dma_free_pages(struct device *dev, struct page *page, > + size_t size, int direction, > + dma_addr_t dma_addr) > +{ > +} > #endif /* CONFIG_DMA_API_DEBUG */ > #endif /* _KERNEL_DMA_DEBUG_H */ > diff --git a/kernel/dma/mapping.c b/kernel/dma/mapping.c > index 107e4a4d251df65fb86a1d7302261c31138061b7..56de28a3b1799f7c18f7e3f8e5ecd438c5748677 100644 > --- a/kernel/dma/mapping.c > +++ b/kernel/dma/mapping.c > @@ -712,7 +712,7 @@ struct page *dma_alloc_pages(struct device *dev, size_t size, > if (page) { > trace_dma_alloc_pages(dev, page_to_virt(page), *dma_handle, > size, dir, gfp, 0); > - debug_dma_map_page(dev, page, 0, size, dir, *dma_handle, 0); > + debug_dma_alloc_pages(dev, page, size, dir, *dma_handle, 0); > } else { > trace_dma_alloc_pages(dev, NULL, 0, size, dir, gfp, 0); > } > @@ -738,7 +738,7 @@ void dma_free_pages(struct device *dev, size_t size, struct page *page, > dma_addr_t dma_handle, enum dma_data_direction dir) > { > trace_dma_free_pages(dev, page_to_virt(page), dma_handle, size, dir, 0); > - debug_dma_unmap_page(dev, dma_handle, size, dir); > + debug_dma_free_pages(dev, page, size, dir, dma_handle); > __dma_free_pages(dev, size, page, dma_handle, dir); > } > EXPORT_SYMBOL_GPL(dma_free_pages); > > --- > base-commit: 95bf875b89b48a95a82aca922eeaf19d52543028 > change-id: 20250828-dma-debug-fix-noncoherent-dma-check-8e6915d58494 > > Best regards, Best regards -- Marek Szyprowski, PhD Samsung R&D Institute Poland ^ permalink raw reply [flat|nested] 2+ messages in thread
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2025-08-28 8:17 ` [PATCH] dma-debug: don't enforce dma mapping check on noncoherent allocations Baochen Qiang
2025-09-02 8:41 ` Marek Szyprowski
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