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authorvenkatesh.pallipadi@intel.com <venkatesh.pallipadi@intel.com>2008-03-19 03:00:20 +0300
committerIngo Molnar <mingo@elte.hu>2008-04-25 01:40:47 +0400
commitf0970c13b6a5b01189aeb196ebb573cf87d95839 (patch)
treec33836b693ca066c19dc8986165aee5849fbcdd9 /drivers/char/mem.c
parente045fb2a988a9a1964059b0d33dbaf18d12f925f (diff)
downloadlinux-f0970c13b6a5b01189aeb196ebb573cf87d95839.tar.xz
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: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com> Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'drivers/char/mem.c')
-rw-r--r--drivers/char/mem.c41
1 files changed, 11 insertions, 30 deletions
diff --git a/drivers/char/mem.c b/drivers/char/mem.c
index 83495885ada0..56b2fb4fbc93 100644
--- a/drivers/char/mem.c
+++ b/drivers/char/mem.c
@@ -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);