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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: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Venki Pallipadi 2008-04-26 11:32:12 -07:00 committed by Ingo Molnar
parent 4a27214d7b
commit 0124cecfc8
1 changed files with 31 additions and 0 deletions
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31
arch/x86/mm/pat.c
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@ -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;
}