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x86: PAT phys_mem_access_prot_allowed for dev/mem mmap

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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: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
venkatesh.pallipadi@intel.com
2008-03-18 17:00:20 -07:00
committed by Ingo Molnar
parent e045fb2a98
commit f0970c13b6
3 changed files with 59 additions and 30 deletions
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41
drivers/char/mem.c
View File

@@ -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);