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authorDavid S. Miller <davem@sunset.davemloft.net>2005-09-29 08:06:47 +0400
committerDavid S. Miller <davem@sunset.davemloft.net>2005-09-29 08:06:47 +0400
commitefdc1e2083e04cc70721d55803889b346c1a3de2 (patch)
tree9f24fab33f795a69bb2dc43a8f3613392762ff02 /arch/sparc64/lib
parent5fd29752f09cabff582f65c0ce35518db4c64937 (diff)
downloadlinux-efdc1e2083e04cc70721d55803889b346c1a3de2.tar.xz
[SPARC64]: Simplify user fault fixup handling.
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>
Diffstat (limited to 'arch/sparc64/lib')
-rw-r--r--arch/sparc64/lib/user_fixup.c63
1 files changed, 29 insertions, 34 deletions
diff --git a/arch/sparc64/lib/user_fixup.c b/arch/sparc64/lib/user_fixup.c
index 0278e34125db..19d1fdb17d0e 100644
--- a/arch/sparc64/lib/user_fixup.c
+++ b/arch/sparc64/lib/user_fixup.c
@@ -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.
*/
-unsigned long copy_from_user_fixup(void *to, const void __user *from, unsigned long size)
+static unsigned long compute_size(unsigned long start, unsigned long size, unsigned long *offset)
{
- char *dst = to;
- const char __user *src = from;
+ unsigned long fault_addr = current_thread_info()->fault_address;
+ unsigned long end = start + size;
- while (size) {
- if (__get_user(*dst, src))
- break;
- dst++;
- src++;
- size--;
+ if (fault_addr < start || fault_addr >= end) {
+ *offset = 0;
+ } else {
+ *offset = start - fault_addr;
+ size = end - fault_addr;
}
+ return size;
+}
- if (size)
- memset(dst, 0, size);
+unsigned long copy_from_user_fixup(void *to, const void __user *from, unsigned long size)
+{
+ unsigned long offset;
+
+ 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;
-
- while (size) {
- if (__put_user(*src, dst))
- break;
- dst++;
- src++;
- size--;
- }
+ unsigned long offset;
- 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;
}