[PATCH 3/4] ARM: Assume new page cache pages have dirty D-cache
Catalin Marinas
catalin.marinas at arm.com
Thu May 20 10:30:15 EDT 2010
There are places in Linux where writes to newly allocated page cache
pages happen without a subsequent call to flush_dcache_page() (several
PIO drivers including USB HCD). This patch changes the meaning of
PG_arch_1 to be PG_dcache_clean and always flush the D-cache for a newly
mapped page in update_mmu_cache().
The patch also sets the PG_arch_1 bit in the DMA cache maintenance
function to avoid additional cache flushing in update_mmu_cache().
Signed-off-by: Catalin Marinas <catalin.marinas at arm.com>
---
arch/arm/include/asm/cacheflush.h | 6 +++---
arch/arm/include/asm/tlbflush.h | 2 +-
arch/arm/mm/copypage-v4mc.c | 2 +-
arch/arm/mm/copypage-v6.c | 2 +-
arch/arm/mm/copypage-xscale.c | 2 +-
arch/arm/mm/dma-mapping.c | 6 ++++++
arch/arm/mm/fault-armv.c | 4 ++--
arch/arm/mm/flush.c | 2 +-
8 files changed, 16 insertions(+), 10 deletions(-)
diff --git a/arch/arm/include/asm/cacheflush.h b/arch/arm/include/asm/cacheflush.h
index 4656a24..d3730f0 100644
--- a/arch/arm/include/asm/cacheflush.h
+++ b/arch/arm/include/asm/cacheflush.h
@@ -137,10 +137,10 @@
#endif
/*
- * This flag is used to indicate that the page pointed to by a pte
- * is dirty and requires cleaning before returning it to the user.
+ * This flag is used to indicate that the page pointed to by a pte is clean
+ * and does not require cleaning before returning it to the user.
*/
-#define PG_dcache_dirty PG_arch_1
+#define PG_dcache_clean PG_arch_1
/*
* MM Cache Management
diff --git a/arch/arm/include/asm/tlbflush.h b/arch/arm/include/asm/tlbflush.h
index bd863d8..40a7092 100644
--- a/arch/arm/include/asm/tlbflush.h
+++ b/arch/arm/include/asm/tlbflush.h
@@ -552,7 +552,7 @@ extern void flush_tlb_kernel_range(unsigned long start, unsigned long end);
#endif
/*
- * if PG_dcache_dirty is set for the page, we need to ensure that any
+ * If PG_dcache_clean is not set for the page, we need to ensure that any
* cache entries for the kernels virtual memory range are written
* back to the page.
*/
diff --git a/arch/arm/mm/copypage-v4mc.c b/arch/arm/mm/copypage-v4mc.c
index 598c51a..b806151 100644
--- a/arch/arm/mm/copypage-v4mc.c
+++ b/arch/arm/mm/copypage-v4mc.c
@@ -73,7 +73,7 @@ void v4_mc_copy_user_highpage(struct page *to, struct page *from,
{
void *kto = kmap_atomic(to, KM_USER1);
- if (test_and_clear_bit(PG_dcache_dirty, &from->flags))
+ if (!test_and_set_bit(PG_dcache_clean, &from->flags))
__flush_dcache_page(page_mapping(from), from);
spin_lock(&minicache_lock);
diff --git a/arch/arm/mm/copypage-v6.c b/arch/arm/mm/copypage-v6.c
index f55fa10..bdba6c6 100644
--- a/arch/arm/mm/copypage-v6.c
+++ b/arch/arm/mm/copypage-v6.c
@@ -79,7 +79,7 @@ static void v6_copy_user_highpage_aliasing(struct page *to,
unsigned int offset = CACHE_COLOUR(vaddr);
unsigned long kfrom, kto;
- if (test_and_clear_bit(PG_dcache_dirty, &from->flags))
+ if (!test_and_set_bit(PG_dcache_clean, &from->flags))
__flush_dcache_page(page_mapping(from), from);
/* FIXME: not highmem safe */
diff --git a/arch/arm/mm/copypage-xscale.c b/arch/arm/mm/copypage-xscale.c
index 9920c0a..649bbcd 100644
--- a/arch/arm/mm/copypage-xscale.c
+++ b/arch/arm/mm/copypage-xscale.c
@@ -95,7 +95,7 @@ void xscale_mc_copy_user_highpage(struct page *to, struct page *from,
{
void *kto = kmap_atomic(to, KM_USER1);
- if (test_and_clear_bit(PG_dcache_dirty, &from->flags))
+ if (!test_and_set_bit(PG_dcache_clean, &from->flags))
__flush_dcache_page(page_mapping(from), from);
spin_lock(&minicache_lock);
diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index 13fa536..bb9b612 100644
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -508,6 +508,12 @@ void ___dma_page_dev_to_cpu(struct page *page, unsigned long off,
outer_inv_range(paddr, paddr + size);
dma_cache_maint_page(page, off, size, dir, dmac_unmap_area);
+
+ /*
+ * Mark the D-cache clean for this page to avoid extra flushing.
+ */
+ if (dir != DMA_TO_DEVICE)
+ set_bit(PG_dcache_clean, &page->flags);
}
EXPORT_SYMBOL(___dma_page_dev_to_cpu);
diff --git a/arch/arm/mm/fault-armv.c b/arch/arm/mm/fault-armv.c
index 9d77d90..91a691f 100644
--- a/arch/arm/mm/fault-armv.c
+++ b/arch/arm/mm/fault-armv.c
@@ -141,7 +141,7 @@ make_coherent(struct address_space *mapping, struct vm_area_struct *vma,
* a page table, or changing an existing PTE. Basically, there are two
* things that we need to take care of:
*
- * 1. If PG_dcache_dirty is set for the page, we need to ensure
+ * 1. If PG_dcache_clean is not set for the page, we need to ensure
* that any cache entries for the kernels virtual memory
* range are written back to the page.
* 2. If we have multiple shared mappings of the same space in
@@ -168,7 +168,7 @@ void update_mmu_cache(struct vm_area_struct *vma, unsigned long addr,
return;
mapping = page_mapping(page);
- if (test_and_clear_bit(PG_dcache_dirty, &page->flags))
+ if (!test_and_set_bit(PG_dcache_clean, &page->flags))
__flush_dcache_page(mapping, page);
if (mapping) {
if (cache_is_vivt())
diff --git a/arch/arm/mm/flush.c b/arch/arm/mm/flush.c
index 5ad8711..5abab9a 100644
--- a/arch/arm/mm/flush.c
+++ b/arch/arm/mm/flush.c
@@ -245,7 +245,7 @@ void flush_dcache_page(struct page *page)
if (!cache_ops_need_broadcast() &&
!PageHighMem(page) && mapping && !mapping_mapped(mapping))
- set_bit(PG_dcache_dirty, &page->flags);
+ clear_bit(PG_dcache_clean, &page->flags);
else {
__flush_dcache_page(mapping, page);
if (mapping && cache_is_vivt())
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