and we have VM_DONTCOPY already, which is used by the DRM code. So it
would only be a question of exporting this API to userspace. The attached
patch adds MAP_DONTCOPY. I made it unpriviledged, i doubt it has any
security impact.
Ingo
--- linux/include/asm-i386/mman.h.orig2 2002-11-18 13:07:16.000000000 +0100
+++ linux/include/asm-i386/mman.h 2002-11-18 13:07:44.000000000 +0100
@@ -20,6 +20,7 @@
#define MAP_NORESERVE 0x4000 /* don't check for reservations */
#define MAP_POPULATE 0x8000 /* populate (prefault) pagetables */
#define MAP_NONBLOCK 0x10000 /* do not block on IO */
+#define MAP_DONTCOPY 0x20000 /* do not block on IO */
#define MS_ASYNC 1 /* sync memory asynchronously */
#define MS_INVALIDATE 2 /* invalidate the caches */
--- linux/mm/mmap.c.orig2 2002-11-18 13:08:03.000000000 +0100
+++ linux/mm/mmap.c 2002-11-18 13:08:44.000000000 +0100
@@ -450,6 +450,11 @@
*/
vm_flags = calc_vm_flags(prot,flags) | mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
+ /*
+ * Copy the mapping on fork?
+ */
+ if (flags & MAP_DONTCOPY)
+ vm_flags |= VM_DONTCOPY;
if (flags & MAP_LOCKED) {
if (!capable(CAP_IPC_LOCK))
return -EPERM;
-
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This archive was generated by hypermail 2b29 : Sat Nov 23 2002 - 22:00:21 EST