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authorvenkatesh.pallipadi@intel.com <venkatesh.pallipadi@intel.com>2008-03-18 17:00:15 -0700
committerIngo Molnar <mingo@elte.hu>2008-04-24 23:40:47 +0200
commite045fb2a988a9a1964059b0d33dbaf18d12f925f (patch)
tree61dbd03abd83dcf6d5195fa6463ea96e125784f6 /arch/x86/mm/ioremap.c
parente2beb3eae627211b67e456c53f946cede2ac10d7 (diff)
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 <venkatesh.pallipadi@intel.com> Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/x86/mm/ioremap.c')
-rw-r--r--arch/x86/mm/ioremap.c29
1 files changed, 29 insertions, 0 deletions
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;