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[SPARC64]: Simplify user fault fixup handling.

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Instead of doing byte-at-a-time user accesses to figure
out where the fault occurred, read the saved fault_address
from the current thread structure.

For the sake of defensive programming, if the fault_address
does not fall into the user buffer range, simply assume the
whole area faulted.  This will cause the fixup for
copy_from_user() to clear the entire kernel side buffer.

Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
David S. Miller
2005-09-28 21:06:47 -07:00
parent 5fd29752f0
commit efdc1e2083
3 changed files with 35 additions and 46 deletions
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65
arch/sparc64/lib/user_fixup.c
View File

@ -11,61 +11,56 @@
/* Calculating the exact fault address when using
* block loads and stores can be very complicated.
*
* Instead of trying to be clever and handling all
* of the cases, just fix things up simply here.
*/
static unsigned long compute_size(unsigned long start, unsigned long size, unsigned long *offset)
{
unsigned long fault_addr = current_thread_info()->fault_address;
unsigned long end = start + size;
if (fault_addr < start || fault_addr >= end) {
*offset = 0;
} else {
*offset = start - fault_addr;
size = end - fault_addr;
}
return size;
}
unsigned long copy_from_user_fixup(void *to, const void __user *from, unsigned long size)
{
char *dst = to;
const char __user *src = from;
unsigned long offset;
while (size) {
if (__get_user(*dst, src))
break;
dst++;
src++;
size--;
}
if (size)
memset(dst, 0, size);
size = compute_size((unsigned long) from, size, &offset);
if (likely(size))
memset(to + offset, 0, size);
return size;
}
unsigned long copy_to_user_fixup(void __user *to, const void *from, unsigned long size)
{
char __user *dst = to;
const char *src = from;
unsigned long offset;
while (size) {
if (__put_user(*src, dst))
break;
dst++;
src++;
size--;
}
return size;
return compute_size((unsigned long) to, size, &offset);
}
unsigned long copy_in_user_fixup(void __user *to, void __user *from, unsigned long size)
{
char __user *dst = to;
char __user *src = from;
unsigned long fault_addr = current_thread_info()->fault_address;
unsigned long start = (unsigned long) to;
unsigned long end = start + size;
while (size) {
char tmp;
if (fault_addr >= start && fault_addr < end)
return end - fault_addr;
if (__get_user(tmp, src))
break;
if (__put_user(tmp, dst))
break;
dst++;
src++;
size--;
}
start = (unsigned long) from;
end = start + size;
if (fault_addr >= start && fault_addr < end)
return end - fault_addr;
return size;
}