From e045fb2a988a9a1964059b0d33dbaf18d12f925f Mon Sep 17 00:00:00 2001 From: "venkatesh.pallipadi@intel.com" Date: Tue, 18 Mar 2008 17:00:15 -0700 Subject: x86: PAT avoid aliasing in /dev/mem read/write Add xlate and unxlate around /dev/mem read/write. This sets up the mapping that can be used for /dev/mem read and write without aliasing worries. Signed-off-by: Venkatesh Pallipadi Signed-off-by: Suresh Siddha Signed-off-by: Ingo Molnar --- arch/x86/mm/ioremap.c | 29 +++++++++++++++++++++++++++++ 1 file changed, 29 insertions(+) (limited to 'arch') diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c index 3a4baf95e24..caac7d5699a 100644 --- a/arch/x86/mm/ioremap.c +++ b/arch/x86/mm/ioremap.c @@ -336,6 +336,35 @@ void iounmap(volatile void __iomem *addr) } EXPORT_SYMBOL(iounmap); +/* + * Convert a physical pointer to a virtual kernel pointer for /dev/mem + * access + */ +void *xlate_dev_mem_ptr(unsigned long phys) +{ + void *addr; + unsigned long start = phys & PAGE_MASK; + + /* If page is RAM, we can use __va. Otherwise ioremap and unmap. */ + if (page_is_ram(start >> PAGE_SHIFT)) + return __va(phys); + + addr = (void *)ioremap(start, PAGE_SIZE); + if (addr) + addr = (void *)((unsigned long)addr | (phys & ~PAGE_MASK)); + + return addr; +} + +void unxlate_dev_mem_ptr(unsigned long phys, void *addr) +{ + if (page_is_ram(phys >> PAGE_SHIFT)) + return; + + iounmap((void __iomem *)((unsigned long)addr & PAGE_MASK)); + return; +} + #ifdef CONFIG_X86_32 int __initdata early_ioremap_debug; -- cgit v1.2.3