>From 247ca658ebeb7c8d04918747ec8a0da45c36bcb8 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Sun, 28 Apr 2019 13:23:26 -0500 Subject: dma-direct: provide generic support for uncached kernel segments 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 --- arch/Kconfig | 8 ++++++++ include/linux/dma-noncoherent.h | 3 +++ kernel/dma/direct.c | 17 +++++++++++++++-- 3 files changed, 26 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..6688e1cee7d1 100644 --- a/kernel/dma/direct.c +++ b/kernel/dma/direct.c @@ -171,6 +171,13 @@ 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); + + 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); + } + return ret; } @@ -189,13 +196,18 @@ 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 +215,8 @@ 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