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Commit e045fb2a authored by venkatesh.pallipadi@intel.com's avatar venkatesh.pallipadi@intel.com Committed by Ingo Molnar
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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: default avatarVenkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: default avatarSuresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent e2beb3ea

arch/x86/mm/ioremap.c

+29 −0
Original line number Diff line number Diff line
@@ -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;

drivers/char/mem.c

+27 −5
Original line number Diff line number Diff line
@@ -134,6 +134,10 @@ static inline int range_is_allowed(unsigned long pfn, unsigned long size) 
}

#endif



void __attribute__((weak)) unxlate_dev_mem_ptr(unsigned long phys, void *addr)

{

}



/*

 * This funcion reads the *physical* memory. The f_pos points directly to the 

 * memory location.
@@ -176,17 +180,25 @@ static ssize_t read_mem(struct file * file, char __user * buf, 


		sz = min_t(unsigned long, sz, count);



		if (!range_is_allowed(p >> PAGE_SHIFT, count))

			return -EPERM;



		/*

		 * On ia64 if a page has been mapped somewhere as

		 * uncached, then it must also be accessed uncached

		 * by the kernel or data corruption may occur

		 */

		ptr = xlate_dev_mem_ptr(p);

		if (!ptr)

			return -EFAULT;



		if (!range_is_allowed(p >> PAGE_SHIFT, count))

			return -EPERM;

		if (copy_to_user(buf, ptr, sz))

		if (copy_to_user(buf, ptr, sz)) {

			unxlate_dev_mem_ptr(p, ptr);

			return -EFAULT;

		}



		unxlate_dev_mem_ptr(p, ptr);



		buf += sz;

		p += sz;

		count -= sz;
@@ -235,22 +247,32 @@ static ssize_t write_mem(struct file * file, const char __user * buf, 


		sz = min_t(unsigned long, sz, count);



		if (!range_is_allowed(p >> PAGE_SHIFT, sz))

			return -EPERM;



		/*

		 * On ia64 if a page has been mapped somewhere as

		 * uncached, then it must also be accessed uncached

		 * by the kernel or data corruption may occur

		 */

		ptr = xlate_dev_mem_ptr(p);

		if (!ptr) {

			if (written)

				break;

			return -EFAULT;

		}



		if (!range_is_allowed(p >> PAGE_SHIFT, sz))

			return -EPERM;

		copied = copy_from_user(ptr, buf, sz);

		if (copied) {

			written += sz - copied;

			unxlate_dev_mem_ptr(p, ptr);

			if (written)

				break;

			return -EFAULT;

		}



		unxlate_dev_mem_ptr(p, ptr);



		buf += sz;

		p += sz;

		count -= sz;

include/asm-x86/io.h

+8 −0
Original line number Diff line number Diff line 
#ifndef _ASM_X86_IO_H

#define _ASM_X86_IO_H



#define ARCH_HAS_IOREMAP_WC



#ifdef CONFIG_X86_32
@@ -5,7 +8,12 @@ 
#else

# include "io_64.h"

#endif



extern void *xlate_dev_mem_ptr(unsigned long phys);

extern void unxlate_dev_mem_ptr(unsigned long phys, void *addr);



extern int ioremap_change_attr(unsigned long vaddr, unsigned long size,

				unsigned long prot_val);

extern void __iomem *ioremap_wc(unsigned long offset, unsigned long size);



#endif /* _ASM_X86_IO_H */

include/asm-x86/io_32.h

+0 −6
Original line number Diff line number Diff line
@@ -48,12 +48,6 @@ 


#include <linux/vmalloc.h>



/*

 * Convert a physical pointer to a virtual kernel pointer for /dev/mem

 * access

 */

#define xlate_dev_mem_ptr(p)	__va(p)



/*

 * Convert a virtual cached pointer to an uncached pointer

 */

include/asm-x86/io_64.h

+0 −6
Original line number Diff line number Diff line
@@ -307,12 +307,6 @@ void memset_io(volatile void __iomem *a, int b, size_t c); 
extern int iommu_bio_merge;

#define BIO_VMERGE_BOUNDARY iommu_bio_merge



/*

 * Convert a physical pointer to a virtual kernel pointer for /dev/mem

 * access

 */

#define xlate_dev_mem_ptr(p)	__va(p)



/*

 * Convert a virtual cached pointer to an uncached pointer

 */