Commit f0970c13 authored by venkatesh.pallipadi@intel.com's avatar venkatesh.pallipadi@intel.com Committed by Ingo Molnar
Browse files

x86: PAT phys_mem_access_prot_allowed for dev/mem mmap 



Introduce phys_mem_access_prot_allowed(), which checks whether the mapping
is possible, without any conflicts and returns success or failure based on that.
phys_mem_access_prot() by itself does not allow failure case. This ability
to return error is needed for PAT where we may have aliasing conflicts.

x86 setup __HAVE_PHYS_MEM_ACCESS_PROT and move x86 specific code out of
/dev/mem into arch specific area.

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 e045fb2a

arch/x86/mm/pat.c

+39 −0
Original line number Diff line number Diff line
@@ -419,3 +419,42 @@ int free_memtype(u64 start, u64 end) 
	return err;

}





/* /dev/mem interface. Use the previous mapping */

pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,

				unsigned long size, pgprot_t vma_prot)

{

	return vma_prot;

}



int phys_mem_access_prot_allowed(struct file *file, unsigned long pfn,

				unsigned long size, pgprot_t *vma_prot)

{



	if (file->f_flags & O_SYNC) {

		*vma_prot = pgprot_noncached(*vma_prot);

		return 1;

	}



#ifdef CONFIG_X86_32

	/*

	 * On the PPro and successors, the MTRRs are used to set

	 * memory types for physical addresses outside main memory,

	 * so blindly setting UC or PWT on those pages is wrong.

	 * For Pentiums and earlier, the surround logic should disable

	 * caching for the high addresses through the KEN pin, but

	 * we maintain the tradition of paranoia in this code.

	 */

	if (!pat_wc_enabled &&

	    ! ( test_bit(X86_FEATURE_MTRR, boot_cpu_data.x86_capability) ||

		test_bit(X86_FEATURE_K6_MTRR, boot_cpu_data.x86_capability) ||

		test_bit(X86_FEATURE_CYRIX_ARR, boot_cpu_data.x86_capability) ||

		test_bit(X86_FEATURE_CENTAUR_MCR, boot_cpu_data.x86_capability)) &&

	   (pfn << PAGE_SHIFT) >= __pa(high_memory)) {

		*vma_prot = pgprot_noncached(*vma_prot);

		return 1;

	}

#endif



	return 1;

}

drivers/char/mem.c

+11 −30
Original line number Diff line number Diff line
@@ -41,36 +41,7 @@ 
 */

static inline int uncached_access(struct file *file, unsigned long addr)

{

#if defined(__i386__) && !defined(__arch_um__)

	/*

	 * On the PPro and successors, the MTRRs are used to set

	 * memory types for physical addresses outside main memory,

	 * so blindly setting PCD or PWT on those pages is wrong.

	 * For Pentiums and earlier, the surround logic should disable

	 * caching for the high addresses through the KEN pin, but

	 * we maintain the tradition of paranoia in this code.

	 */

	if (file->f_flags & O_SYNC)

		return 1;

 	return !( test_bit(X86_FEATURE_MTRR, boot_cpu_data.x86_capability) ||

		  test_bit(X86_FEATURE_K6_MTRR, boot_cpu_data.x86_capability) ||

		  test_bit(X86_FEATURE_CYRIX_ARR, boot_cpu_data.x86_capability) ||

		  test_bit(X86_FEATURE_CENTAUR_MCR, boot_cpu_data.x86_capability) )

	  && addr >= __pa(high_memory);

#elif defined(__x86_64__) && !defined(__arch_um__)

	/* 

	 * This is broken because it can generate memory type aliases,

	 * which can cause cache corruptions

	 * But it is only available for root and we have to be bug-to-bug

	 * compatible with i386.

	 */

	if (file->f_flags & O_SYNC)

		return 1;

	/* same behaviour as i386. PAT always set to cached and MTRRs control the

	   caching behaviour. 

	   Hopefully a full PAT implementation will fix that soon. */	   

	return 0;

#elif defined(CONFIG_IA64)

#if defined(CONFIG_IA64)

	/*

	 * On ia64, we ignore O_SYNC because we cannot tolerate memory attribute aliases.

	 */
@@ -283,6 +254,12 @@ static ssize_t write_mem(struct file * file, const char __user * buf, 
	return written;

}



int __attribute__((weak)) phys_mem_access_prot_allowed(struct file *file,

	unsigned long pfn, unsigned long size, pgprot_t *vma_prot)

{

	return 1;

}



#ifndef __HAVE_PHYS_MEM_ACCESS_PROT

static pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,

				     unsigned long size, pgprot_t vma_prot)
@@ -336,6 +313,10 @@ static int mmap_mem(struct file * file, struct vm_area_struct * vma) 
	if (!range_is_allowed(vma->vm_pgoff, size))

		return -EPERM;



	if (!phys_mem_access_prot_allowed(file, vma->vm_pgoff, size,

						&vma->vm_page_prot))

		return -EINVAL;



	vma->vm_page_prot = phys_mem_access_prot(file, vma->vm_pgoff,

						 size,

						 vma->vm_page_prot);

include/asm-x86/pgtable.h

+9 −0
Original line number Diff line number Diff line
@@ -289,6 +289,15 @@ static inline pte_t pte_modify(pte_t pte, pgprot_t newprot) 


#define canon_pgprot(p) __pgprot(pgprot_val(p) & __supported_pte_mask)



#ifndef __ASSEMBLY__

#define __HAVE_PHYS_MEM_ACCESS_PROT

struct file;

pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,

                              unsigned long size, pgprot_t vma_prot);

int phys_mem_access_prot_allowed(struct file *file, unsigned long pfn,

                              unsigned long size, pgprot_t *vma_prot);

#endif



#ifdef CONFIG_PARAVIRT

#include <asm/paravirt.h>

#else  /* !CONFIG_PARAVIRT */

CRA Git | Maintained and supported by SUSTech CRA and CCSE