diff options
| author | Russell King <rmk+kernel@arm.linux.org.uk> | 2009-10-25 10:23:04 +0000 |
|---|---|---|
| committer | Russell King <rmk+kernel@arm.linux.org.uk> | 2009-12-01 18:20:07 +0000 |
| commit | 421fe93cc4b06b2f5e875cbe0f692800d4862ee5 (patch) | |
| tree | 88c5985799273a7c854159246d715e1ad85646f9 | |
| parent | b7dc0b2cfc6e9bc7270915c642a8a8e999b6095e (diff) | |
ARM: ZERO_PAGE: Avoid flush_dcache_page() for zero page
The zero page is read-only, and has its cache state cleared during
boot. No further maintanence for this page is required.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
| -rw-r--r-- | arch/arm/mm/fault-armv.c | 7 | ||||
| -rw-r--r-- | arch/arm/mm/flush.c | 11 | ||||
| -rw-r--r-- | arch/arm/mm/mmu.c | 2 |
3 files changed, 18 insertions, 2 deletions
diff --git a/arch/arm/mm/fault-armv.c b/arch/arm/mm/fault-armv.c index d0d17b6a3703..4fbc7de8b4ac 100644 --- a/arch/arm/mm/fault-armv.c +++ b/arch/arm/mm/fault-armv.c @@ -151,7 +151,14 @@ void update_mmu_cache(struct vm_area_struct *vma, unsigned long addr, pte_t pte) if (!pfn_valid(pfn)) return; + /* + * The zero page is never written to, so never has any dirty + * cache lines, and therefore never needs to be flushed. + */ page = pfn_to_page(pfn); + if (page == ZERO_PAGE(0)) + return; + mapping = page_mapping(page); #ifndef CONFIG_SMP if (test_and_clear_bit(PG_dcache_dirty, &page->flags)) diff --git a/arch/arm/mm/flush.c b/arch/arm/mm/flush.c index 43474d8752a6..82f4b06bf6b4 100644 --- a/arch/arm/mm/flush.c +++ b/arch/arm/mm/flush.c @@ -189,7 +189,16 @@ static void __flush_dcache_aliases(struct address_space *mapping, struct page *p */ void flush_dcache_page(struct page *page) { - struct address_space *mapping = page_mapping(page); + struct address_space *mapping; + + /* + * The zero page is never written to, so never has any dirty + * cache lines, and therefore never needs to be flushed. + */ + if (page == ZERO_PAGE(0)) + return; + + mapping = page_mapping(page); #ifndef CONFIG_SMP if (!PageHighMem(page) && mapping && !mapping_mapped(mapping)) diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c index ea67be0223ac..2427cdcd9098 100644 --- a/arch/arm/mm/mmu.c +++ b/arch/arm/mm/mmu.c @@ -1036,7 +1036,7 @@ void __init paging_init(struct machine_desc *mdesc) */ zero_page = alloc_bootmem_low_pages(PAGE_SIZE); empty_zero_page = virt_to_page(zero_page); - flush_dcache_page(empty_zero_page); + __flush_dcache_page(NULL, empty_zero_page); } /* |