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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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39
arch/x86/mm/pat.c
View file

@ -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;
}

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);

9
include/asm-x86/pgtable.h
View file

@ -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 */