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Commit 0124cecf authored by Venki Pallipadi's avatar Venki Pallipadi Committed by Ingo Molnar
Browse files

x86, PAT: disable /dev/mem mmap RAM with PAT 



disable /dev/mem mmap of RAM with PAT. It makes things safer and
eliminates aliasing. A future improvement would be to avoid the
range_is_allowed duplication.

Signed-off-by: default avatarVenkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 4a27214d

arch/x86/mm/pat.c

+31 −0
Original line number Diff line number Diff line
@@ -16,6 +16,7 @@ 
#include <asm/msr.h>

#include <asm/tlbflush.h>

#include <asm/processor.h>

#include <asm/page.h>

#include <asm/pgtable.h>

#include <asm/pat.h>

#include <asm/e820.h>
@@ -477,6 +478,33 @@ pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn, 
	return vma_prot;

}



#ifdef CONFIG_NONPROMISC_DEVMEM

/* This check is done in drivers/char/mem.c in case of NONPROMISC_DEVMEM*/

static inline int range_is_allowed(unsigned long pfn, unsigned long size)

{

	return 1;

}

#else

static inline int range_is_allowed(unsigned long pfn, unsigned long size)

{

	u64 from = ((u64)pfn) << PAGE_SHIFT;

	u64 to = from + size;

	u64 cursor = from;



	while (cursor < to) {

		if (!devmem_is_allowed(pfn)) {

			printk(KERN_INFO

		"Program %s tried to access /dev/mem between %Lx->%Lx.\n",

				current->comm, from, to);

			return 0;

		}

		cursor += PAGE_SIZE;

		pfn++;

	}

	return 1;

}

#endif /* CONFIG_NONPROMISC_DEVMEM */



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

				unsigned long size, pgprot_t *vma_prot)

{
@@ -485,6 +513,9 @@ int phys_mem_access_prot_allowed(struct file *file, unsigned long pfn, 
	unsigned long ret_flags;

	int retval;



	if (!range_is_allowed(pfn, size))

		return 0;



	if (file->f_flags & O_SYNC) {

		flags = _PAGE_CACHE_UC;

	}