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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>
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parent
e2beb3eae6
commit
e045fb2a98
5 changed files with 69 additions and 22 deletions
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@ -336,6 +336,35 @@ void iounmap(volatile void __iomem *addr)
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}
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EXPORT_SYMBOL(iounmap);
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/*
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* Convert a physical pointer to a virtual kernel pointer for /dev/mem
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* access
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*/
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void *xlate_dev_mem_ptr(unsigned long phys)
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{
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void *addr;
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unsigned long start = phys & PAGE_MASK;
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/* If page is RAM, we can use __va. Otherwise ioremap and unmap. */
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if (page_is_ram(start >> PAGE_SHIFT))
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return __va(phys);
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addr = (void *)ioremap(start, PAGE_SIZE);
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if (addr)
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addr = (void *)((unsigned long)addr | (phys & ~PAGE_MASK));
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return addr;
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}
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void unxlate_dev_mem_ptr(unsigned long phys, void *addr)
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{
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if (page_is_ram(phys >> PAGE_SHIFT))
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return;
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iounmap((void __iomem *)((unsigned long)addr & PAGE_MASK));
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return;
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}
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#ifdef CONFIG_X86_32
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int __initdata early_ioremap_debug;
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@ -134,6 +134,10 @@ static inline int range_is_allowed(unsigned long pfn, unsigned long size)
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}
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#endif
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void __attribute__((weak)) unxlate_dev_mem_ptr(unsigned long phys, void *addr)
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{
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}
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/*
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* This funcion reads the *physical* memory. The f_pos points directly to the
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* memory location.
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@ -176,17 +180,25 @@ static ssize_t read_mem(struct file * file, char __user * buf,
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sz = min_t(unsigned long, sz, count);
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if (!range_is_allowed(p >> PAGE_SHIFT, count))
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return -EPERM;
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/*
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* On ia64 if a page has been mapped somewhere as
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* uncached, then it must also be accessed uncached
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* by the kernel or data corruption may occur
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*/
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ptr = xlate_dev_mem_ptr(p);
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if (!range_is_allowed(p >> PAGE_SHIFT, count))
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return -EPERM;
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if (copy_to_user(buf, ptr, sz))
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if (!ptr)
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return -EFAULT;
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if (copy_to_user(buf, ptr, sz)) {
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unxlate_dev_mem_ptr(p, ptr);
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return -EFAULT;
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}
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unxlate_dev_mem_ptr(p, ptr);
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buf += sz;
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p += sz;
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count -= sz;
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@ -235,22 +247,32 @@ static ssize_t write_mem(struct file * file, const char __user * buf,
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sz = min_t(unsigned long, sz, count);
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if (!range_is_allowed(p >> PAGE_SHIFT, sz))
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return -EPERM;
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/*
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* On ia64 if a page has been mapped somewhere as
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* uncached, then it must also be accessed uncached
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* by the kernel or data corruption may occur
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*/
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ptr = xlate_dev_mem_ptr(p);
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if (!range_is_allowed(p >> PAGE_SHIFT, sz))
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return -EPERM;
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copied = copy_from_user(ptr, buf, sz);
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if (copied) {
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written += sz - copied;
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if (!ptr) {
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if (written)
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break;
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return -EFAULT;
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}
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copied = copy_from_user(ptr, buf, sz);
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if (copied) {
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written += sz - copied;
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unxlate_dev_mem_ptr(p, ptr);
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if (written)
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break;
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return -EFAULT;
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}
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unxlate_dev_mem_ptr(p, ptr);
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buf += sz;
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p += sz;
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count -= sz;
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@ -1,3 +1,6 @@
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#ifndef _ASM_X86_IO_H
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#define _ASM_X86_IO_H
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#define ARCH_HAS_IOREMAP_WC
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#ifdef CONFIG_X86_32
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@ -5,7 +8,12 @@
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#else
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# include "io_64.h"
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#endif
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extern void *xlate_dev_mem_ptr(unsigned long phys);
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extern void unxlate_dev_mem_ptr(unsigned long phys, void *addr);
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extern int ioremap_change_attr(unsigned long vaddr, unsigned long size,
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unsigned long prot_val);
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extern void __iomem *ioremap_wc(unsigned long offset, unsigned long size);
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#endif /* _ASM_X86_IO_H */
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@ -48,12 +48,6 @@
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#include <linux/vmalloc.h>
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/*
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* Convert a physical pointer to a virtual kernel pointer for /dev/mem
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* access
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*/
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#define xlate_dev_mem_ptr(p) __va(p)
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/*
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* Convert a virtual cached pointer to an uncached pointer
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*/
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@ -307,12 +307,6 @@ void memset_io(volatile void __iomem *a, int b, size_t c);
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extern int iommu_bio_merge;
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#define BIO_VMERGE_BOUNDARY iommu_bio_merge
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/*
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* Convert a physical pointer to a virtual kernel pointer for /dev/mem
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* access
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*/
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#define xlate_dev_mem_ptr(p) __va(p)
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/*
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* Convert a virtual cached pointer to an uncached pointer
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*/
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