[PATCH 4/7] dma-direct: provide generic support for uncached kernel segments
From: Christoph Hellwig <hch@lst.de>
Date: 2019-04-30 11:01:25
Also in:
linux-iommu, linux-mips, lkml
Subsystem:
dma mapping helpers, the rest · Maintainers:
Marek Szyprowski, Linus Torvalds
A few architectures support uncached kernel segments. In that case we get an uncached mapping for a given physica address by using an offset in the uncached segement. Implement support for this scheme in the generic dma-direct code instead of duplicating it in arch hooks. Signed-off-by: Christoph Hellwig <hch@lst.de> --- arch/Kconfig | 8 ++++++++ include/linux/dma-noncoherent.h | 3 +++ kernel/dma/direct.c | 18 ++++++++++++++++-- 3 files changed, 27 insertions(+), 2 deletions(-)
diff --git a/arch/Kconfig b/arch/Kconfig
index 33687dddd86a..ea22a8c894ec 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig@@ -249,6 +249,14 @@ config ARCH_HAS_FORTIFY_SOURCE config ARCH_HAS_SET_MEMORY bool +# +# Select if arch has an uncached kernel segment and provides the +# uncached_kernel_address / cached_kernel_address symbols to use it +# +config ARCH_HAS_UNCACHED_SEGMENT + select ARCH_HAS_DMA_PREP_COHERENT + bool + # Select if arch init_task must go in the __init_task_data section config ARCH_TASK_STRUCT_ON_STACK bool
diff --git a/include/linux/dma-noncoherent.h b/include/linux/dma-noncoherent.h
index 9741767e400f..7e0126a04e02 100644
--- a/include/linux/dma-noncoherent.h
+++ b/include/linux/dma-noncoherent.h@@ -80,4 +80,7 @@ static inline void arch_dma_prep_coherent(struct page *page, size_t size) } #endif /* CONFIG_ARCH_HAS_DMA_PREP_COHERENT */ +void *uncached_kernel_address(void *addr); +void *cached_kernel_address(void *addr); + #endif /* _LINUX_DMA_NONCOHERENT_H */
diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
index 2c2772e9702a..d15a535c3e67 100644
--- a/kernel/dma/direct.c
+++ b/kernel/dma/direct.c@@ -164,6 +164,13 @@ void *dma_direct_alloc_pages(struct device *dev, size_t size, } ret = page_address(page); + + if (IS_ENABLED(CONFIG_ARCH_HAS_UNCACHED_SEGMENT) && + !dev_is_dma_coherent(dev) && !(attrs & DMA_ATTR_NON_CONSISTENT)) { + arch_dma_prep_coherent(page, size); + ret = uncached_kernel_address(ret); + } + if (force_dma_unencrypted()) { set_memory_decrypted((unsigned long)ret, 1 << get_order(size)); *dma_handle = __phys_to_dma(dev, page_to_phys(page));
@@ -171,6 +178,7 @@ void *dma_direct_alloc_pages(struct device *dev, size_t size, *dma_handle = phys_to_dma(dev, page_to_phys(page)); } memset(ret, 0, size); + return ret; }
@@ -189,13 +197,18 @@ void dma_direct_free_pages(struct device *dev, size_t size, void *cpu_addr, if (force_dma_unencrypted()) set_memory_encrypted((unsigned long)cpu_addr, 1 << page_order); + + if (IS_ENABLED(CONFIG_ARCH_HAS_UNCACHED_SEGMENT) && + !dev_is_dma_coherent(dev) && !(attrs & DMA_ATTR_NON_CONSISTENT)) + cpu_addr = cached_kernel_address(cpu_addr); __dma_direct_free_pages(dev, size, virt_to_page(cpu_addr)); } void *dma_direct_alloc(struct device *dev, size_t size, dma_addr_t *dma_handle, gfp_t gfp, unsigned long attrs) { - if (!dev_is_dma_coherent(dev)) + if (!IS_ENABLED(CONFIG_ARCH_HAS_UNCACHED_SEGMENT) && + !dev_is_dma_coherent(dev)) return arch_dma_alloc(dev, size, dma_handle, gfp, attrs); return dma_direct_alloc_pages(dev, size, dma_handle, gfp, attrs); }
@@ -203,7 +216,8 @@ void *dma_direct_alloc(struct device *dev, size_t size, void dma_direct_free(struct device *dev, size_t size, void *cpu_addr, dma_addr_t dma_addr, unsigned long attrs) { - if (!dev_is_dma_coherent(dev)) + if (!IS_ENABLED(CONFIG_ARCH_HAS_UNCACHED_SEGMENT) && + !dev_is_dma_coherent(dev)) arch_dma_free(dev, size, cpu_addr, dma_addr, attrs); else dma_direct_free_pages(dev, size, cpu_addr, dma_addr, attrs);
--
2.20.1