[RFCv2][PATCH 2/5] arm: Implement ARCH_HAS_FORCE_CACHE
Laura Abbott
labbott at redhat.com
Mon Aug 8 10:49:34 PDT 2016
arm may need the kernel_force_cache APIs to guarantee data consistency.
Implement versions of these APIs based on the DMA APIs.
Signed-off-by: Laura Abbott <labbott at redhat.com>
---
arch/arm/include/asm/cacheflush.h | 4 ++
arch/arm/mm/dma-mapping.c | 119 --------------------------------------
arch/arm/mm/flush.c | 115 ++++++++++++++++++++++++++++++++++++
arch/arm/mm/mm.h | 8 +++
4 files changed, 127 insertions(+), 119 deletions(-)
diff --git a/arch/arm/include/asm/cacheflush.h b/arch/arm/include/asm/cacheflush.h
index 9156fc3..78eb011 100644
--- a/arch/arm/include/asm/cacheflush.h
+++ b/arch/arm/include/asm/cacheflush.h
@@ -518,4 +518,8 @@ static inline void secure_flush_area(const void *addr, size_t size)
outer_flush_range(phys, phys + size);
}
+#define ARCH_HAS_FORCE_CACHE 1
+void kernel_force_cache_clean(struct page *page, size_t size);
+void kernel_force_cache_invalidate(struct page *page, size_t size);
+
#endif
diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index c6834c0..8c9296d 100644
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -95,23 +95,6 @@ static struct arm_dma_buffer *arm_dma_buffer_find(void *virt)
return found;
}
-/*
- * The DMA API is built upon the notion of "buffer ownership". A buffer
- * is either exclusively owned by the CPU (and therefore may be accessed
- * by it) or exclusively owned by the DMA device. These helper functions
- * represent the transitions between these two ownership states.
- *
- * Note, however, that on later ARMs, this notion does not work due to
- * speculative prefetches. We model our approach on the assumption that
- * the CPU does do speculative prefetches, which means we clean caches
- * before transfers and delay cache invalidation until transfer completion.
- *
- */
-static void __dma_page_cpu_to_dev(struct page *, unsigned long,
- size_t, enum dma_data_direction);
-static void __dma_page_dev_to_cpu(struct page *, unsigned long,
- size_t, enum dma_data_direction);
-
/**
* arm_dma_map_page - map a portion of a page for streaming DMA
* @dev: valid struct device pointer, or NULL for ISA and EISA-like devices
@@ -945,108 +928,6 @@ int arm_dma_get_sgtable(struct device *dev, struct sg_table *sgt,
return 0;
}
-static void dma_cache_maint_page(struct page *page, unsigned long offset,
- size_t size, enum dma_data_direction dir,
- void (*op)(const void *, size_t, int))
-{
- unsigned long pfn;
- size_t left = size;
-
- pfn = page_to_pfn(page) + offset / PAGE_SIZE;
- offset %= PAGE_SIZE;
-
- /*
- * A single sg entry may refer to multiple physically contiguous
- * pages. But we still need to process highmem pages individually.
- * If highmem is not configured then the bulk of this loop gets
- * optimized out.
- */
- do {
- size_t len = left;
- void *vaddr;
-
- page = pfn_to_page(pfn);
-
- if (PageHighMem(page)) {
- if (len + offset > PAGE_SIZE)
- len = PAGE_SIZE - offset;
-
- if (cache_is_vipt_nonaliasing()) {
- vaddr = kmap_atomic(page);
- op(vaddr + offset, len, dir);
- kunmap_atomic(vaddr);
- } else {
- vaddr = kmap_high_get(page);
- if (vaddr) {
- op(vaddr + offset, len, dir);
- kunmap_high(page);
- }
- }
- } else {
- vaddr = page_address(page) + offset;
- op(vaddr, len, dir);
- }
- offset = 0;
- pfn++;
- left -= len;
- } while (left);
-}
-
-/*
- * Make an area consistent for devices.
- * Note: Drivers should NOT use this function directly, as it will break
- * platforms with CONFIG_DMABOUNCE.
- * Use the driver DMA support - see dma-mapping.h (dma_sync_*)
- */
-static void __dma_page_cpu_to_dev(struct page *page, unsigned long off,
- size_t size, enum dma_data_direction dir)
-{
- phys_addr_t paddr;
-
- dma_cache_maint_page(page, off, size, dir, dmac_map_area);
-
- paddr = page_to_phys(page) + off;
- if (dir == DMA_FROM_DEVICE) {
- outer_inv_range(paddr, paddr + size);
- } else {
- outer_clean_range(paddr, paddr + size);
- }
- /* FIXME: non-speculating: flush on bidirectional mappings? */
-}
-
-static void __dma_page_dev_to_cpu(struct page *page, unsigned long off,
- size_t size, enum dma_data_direction dir)
-{
- phys_addr_t paddr = page_to_phys(page) + off;
-
- /* FIXME: non-speculating: not required */
- /* in any case, don't bother invalidating if DMA to device */
- if (dir != DMA_TO_DEVICE) {
- outer_inv_range(paddr, paddr + size);
-
- dma_cache_maint_page(page, off, size, dir, dmac_unmap_area);
- }
-
- /*
- * Mark the D-cache clean for these pages to avoid extra flushing.
- */
- if (dir != DMA_TO_DEVICE && size >= PAGE_SIZE) {
- unsigned long pfn;
- size_t left = size;
-
- pfn = page_to_pfn(page) + off / PAGE_SIZE;
- off %= PAGE_SIZE;
- if (off) {
- pfn++;
- left -= PAGE_SIZE - off;
- }
- while (left >= PAGE_SIZE) {
- page = pfn_to_page(pfn++);
- set_bit(PG_dcache_clean, &page->flags);
- left -= PAGE_SIZE;
- }
- }
-}
/**
* arm_dma_map_sg - map a set of SG buffers for streaming mode DMA
diff --git a/arch/arm/mm/flush.c b/arch/arm/mm/flush.c
index 3cced84..2b8b705 100644
--- a/arch/arm/mm/flush.c
+++ b/arch/arm/mm/flush.c
@@ -11,6 +11,7 @@
#include <linux/mm.h>
#include <linux/pagemap.h>
#include <linux/highmem.h>
+#include <linux/dma-mapping.h>
#include <asm/cacheflush.h>
#include <asm/cachetype.h>
@@ -20,6 +21,7 @@
#include <linux/hugetlb.h>
#include "mm.h"
+#include "dma.h"
#ifdef CONFIG_ARM_HEAVY_MB
void (*soc_mb)(void);
@@ -415,3 +417,116 @@ void __flush_anon_page(struct vm_area_struct *vma, struct page *page, unsigned l
*/
__cpuc_flush_dcache_area(page_address(page), PAGE_SIZE);
}
+
+static void dma_cache_maint_page(struct page *page, unsigned long offset,
+ size_t size, enum dma_data_direction dir,
+ void (*op)(const void *, size_t, int))
+{
+ unsigned long pfn;
+ size_t left = size;
+
+ pfn = page_to_pfn(page) + offset / PAGE_SIZE;
+ offset %= PAGE_SIZE;
+
+ /*
+ * A single sg entry may refer to multiple physically contiguous
+ * pages. But we still need to process highmem pages individually.
+ * If highmem is not configured then the bulk of this loop gets
+ * optimized out.
+ */
+ do {
+ size_t len = left;
+ void *vaddr;
+
+ page = pfn_to_page(pfn);
+
+ if (PageHighMem(page)) {
+ if (len + offset > PAGE_SIZE)
+ len = PAGE_SIZE - offset;
+
+ if (cache_is_vipt_nonaliasing()) {
+ vaddr = kmap_atomic(page);
+ op(vaddr + offset, len, dir);
+ kunmap_atomic(vaddr);
+ } else {
+ vaddr = kmap_high_get(page);
+ if (vaddr) {
+ op(vaddr + offset, len, dir);
+ kunmap_high(page);
+ }
+ }
+ } else {
+ vaddr = page_address(page) + offset;
+ op(vaddr, len, dir);
+ }
+ offset = 0;
+ pfn++;
+ left -= len;
+ } while (left);
+}
+
+/*
+ * Make an area consistent for devices.
+ * Note: Drivers should NOT use this function directly, as it will break
+ * platforms with CONFIG_DMABOUNCE.
+ * Use the driver DMA support - see dma-mapping.h (dma_sync_*)
+ */
+void __dma_page_cpu_to_dev(struct page *page, unsigned long off,
+ size_t size, enum dma_data_direction dir)
+{
+ phys_addr_t paddr;
+
+ dma_cache_maint_page(page, off, size, dir, dmac_map_area);
+
+ paddr = page_to_phys(page) + off;
+ if (dir == DMA_FROM_DEVICE) {
+ outer_inv_range(paddr, paddr + size);
+ } else {
+ outer_clean_range(paddr, paddr + size);
+ }
+ /* FIXME: non-speculating: flush on bidirectional mappings? */
+}
+
+void __dma_page_dev_to_cpu(struct page *page, unsigned long off,
+ size_t size, enum dma_data_direction dir)
+{
+ phys_addr_t paddr = page_to_phys(page) + off;
+
+ /* FIXME: non-speculating: not required */
+ /* in any case, don't bother invalidating if DMA to device */
+ if (dir != DMA_TO_DEVICE) {
+ outer_inv_range(paddr, paddr + size);
+
+ dma_cache_maint_page(page, off, size, dir, dmac_unmap_area);
+ }
+
+ /*
+ * Mark the D-cache clean for these pages to avoid extra flushing.
+ */
+ if (dir != DMA_TO_DEVICE && size >= PAGE_SIZE) {
+ unsigned long pfn;
+ size_t left = size;
+
+ pfn = page_to_pfn(page) + off / PAGE_SIZE;
+ off %= PAGE_SIZE;
+ if (off) {
+ pfn++;
+ left -= PAGE_SIZE - off;
+ }
+ while (left >= PAGE_SIZE) {
+ page = pfn_to_page(pfn++);
+ set_bit(PG_dcache_clean, &page->flags);
+ left -= PAGE_SIZE;
+ }
+ }
+}
+
+void kernel_force_cache_clean(struct page *page, size_t size)
+{
+ __dma_page_cpu_to_dev(page, 0, size, DMA_BIDIRECTIONAL);
+}
+
+void kernel_force_cache_invalidate(struct page *page, size_t size)
+{
+ __dma_page_dev_to_cpu(page, 0, size, DMA_BIDIRECTIONAL);
+}
diff --git a/arch/arm/mm/mm.h b/arch/arm/mm/mm.h
index ce727d4..9b853ac 100644
--- a/arch/arm/mm/mm.h
+++ b/arch/arm/mm/mm.h
@@ -1,9 +1,11 @@
#ifdef CONFIG_MMU
#include <linux/list.h>
#include <linux/vmalloc.h>
+#include <linux/dma-mapping.h>
#include <asm/pgtable.h>
+
/* the upper-most page table pointer */
extern pmd_t *top_pmd;
@@ -97,3 +99,9 @@ void arm_mm_memblock_reserve(void);
void dma_contiguous_remap(void);
unsigned long __clear_cr(unsigned long mask);
+
+void __dma_page_dev_to_cpu(struct page *page, unsigned long off,
+ size_t size, enum dma_data_direction dir);
+
+void __dma_page_cpu_to_dev(struct page *page, unsigned long off,
+ size_t size, enum dma_data_direction dir);
--
2.7.4
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