From d907387c42e9e39261629890e45a08ef4c3ed3fe Mon Sep 17 00:00:00 2001 From: Catalin Marinas Date: Mon, 13 Sep 2010 16:01:24 +0100 Subject: ARM: 6383/1: Implement phys_mem_access_prot() to avoid attributes aliasing ARMv7 onwards requires that there are no aliases to the same physical location using different memory types (i.e. Normal vs Strongly Ordered). Access to SO mappings when the unaligned accesses are handled in hardware is also Unpredictable (pgprot_noncached() mappings in user space). The /dev/mem driver requires uncached mappings with O_SYNC. The patch implements the phys_mem_access_prot() function which generates Strongly Ordered memory attributes if !pfn_valid() (independent of O_SYNC) and Normal Noncacheable (writecombine) if O_SYNC. Signed-off-by: Catalin Marinas Signed-off-by: Russell King --- arch/arm/mm/mmu.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) (limited to 'arch/arm/mm/mmu.c') diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c index 6e1c4f6a2b3f..a486bd0d97dc 100644 --- a/arch/arm/mm/mmu.c +++ b/arch/arm/mm/mmu.c @@ -15,6 +15,7 @@ #include #include #include +#include #include #include @@ -498,6 +499,19 @@ static void __init build_mem_type_table(void) } } +#ifdef CONFIG_ARM_DMA_MEM_BUFFERABLE +pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn, + unsigned long size, pgprot_t vma_prot) +{ + if (!pfn_valid(pfn)) + return pgprot_noncached(vma_prot); + else if (file->f_flags & O_SYNC) + return pgprot_writecombine(vma_prot); + return vma_prot; +} +EXPORT_SYMBOL(phys_mem_access_prot); +#endif + #define vectors_base() (vectors_high() ? 0xffff0000 : 0) static void __init *early_alloc(unsigned long sz) -- cgit v1.2.3