Changeset 2919 in vbox

Timestamp:

May 29, 2007 2:43:31 PM (18 years ago)

Author:

vboxsync

svn:sync-xref-src-repo-rev:

21592

Message:

Stricter checks for patch jumps.
Do not check for page boundary crossing when a patch jump will not be installed.

File:

• trunk/src/VBox/VMM/PATM/PATM.cpp (modified) (2 diffs)

trunk/src/VBox/VMM/PATM/PATM.cpp

@@ -2677 +2677 @@
     }
 
-    if (PAGE_ADDRESS(pInstrGC) != PAGE_ADDRESS(pInstrGC + SIZEOF_NEARJUMP32))
+    if (!(pPatch->flags & (PATMFL_IDTHANDLER|PATMFL_IDTHANDLER_WITHOUT_ENTRYPOINT|PATMFL_SYSENTER|PATMFL_INT3_REPLACEMENT_BLOCK)))   
+        pPatch->flags |= PATMFL_MUST_INSTALL_PATCHJMP;
+
+    /* If we're going to insert a patch jump, then the jump itself is not allowed to cross a page boundary. */
+    if (     (pPatch->flags & PATMFL_MUST_INSTALL_PATCHJMP)
+        &&   PAGE_ADDRESS(pInstrGC) != PAGE_ADDRESS(pInstrGC + SIZEOF_NEARJUMP32)
+       )
     {
         STAM_COUNTER_INC(&pVM->patm.s.StatPageBoundaryCrossed);
@@ -2794 +2800 @@
         STAM_COUNTER_INC(&pVM->patm.s.StatInt3Callable);
     }
-    else
-    if (!(pPatch->flags & PATMFL_IDTHANDLER))
-    {
-        pPatch->flags |= PATMFL_MUST_INSTALL_PATCHJMP;
-
+
+    if (pPatch->flags & PATMFL_MUST_INSTALL_PATCHJMP)
+    {
+        Assert(!(pPatch->flags & (PATMFL_IDTHANDLER|PATMFL_IDTHANDLER_WITHOUT_ENTRYPOINT|PATMFL_SYSENTER|PATMFL_INT3_REPLACEMENT_BLOCK)));
         /* now insert a jump in the guest code */
         rc = patmGenJumpToPatch(pVM, pPatch, true);