Changeset 23099 in vbox for trunk/src/VBox/VMM/PATM

Timestamp:

Sep 17, 2009 2:39:06 PM (15 years ago)

Author:

vboxsync

Message:

PATM: implemented couple tweaks to make NetBSD bootable (still some spurious segfaults)

Location:

trunk/src/VBox/VMM/PATM

Files:

• PATM.cpp (modified) (3 diffs)
• PATMInternal.h (modified) (2 diffs)

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

@@ -167 +167 @@
 # endif
 #endif
+    pVM->patm.s.uPATMFlags = 0;
+    bool fSearchBackward;
+    CFGMR3QueryBoolDef(CFGMR3GetChild(CFGMR3GetRoot(pVM), "PATM"), "SearchImmediatesBackward", &fSearchBackward, false);
+    if (fSearchBackward)
+        pVM->patm.s.uPATMFlags |= PATMGFL_SEARCH_IMM_BACKWARD;
 
     rc = patmReinit(pVM);
@@ -1546 +1551 @@
 
 /**
+ * Checks if few instructions before patch contain something
+ * which looks like immediate referring potential patch instruction
+ *
+ * @returns boolean
+ * @param   pVM         The VM to operate on.
+ * @param   pInstrGC    Guest context pointer to instruction
+ */
+static bool patmHasImmsReferringPatch(PVM pVM, RCPTRTYPE(uint8_t *) pInstrGC)
+{
+    int rc;
+    uint32_t value;
+
+    if (!(pVM->patm.s.uPATMFlags & PATMGFL_SEARCH_IMM_BACKWARD))
+        return false;
+
+    PVMCPU pCpu = VMMGetCpu0(pVM);
+    for (int i = 4; i < 12; i++)
+    {
+        rc = PGMPhysSimpleReadGCPtr(pCpu, &value, pInstrGC - i, 4);
+        if (rc == VINF_SUCCESS)
+        {
+            if ((uint32_t)(value-(uint32_t)pInstrGC) < 6)
+                return true;
+        }
+        else
+            break;
+    }
+    return false;
+}
+
+/**
  * Recompiles the instructions in a code block
  *
@@ -1573 +1609 @@
         Log(("patmRecompileCallback: jump to code we've recompiled before %RRv!\n", pCurInstrGC));
         return patmPatchGenRelJump(pVM, pPatch, pCurInstrGC, OP_JMP, !!(pCpu->prefix & PREFIX_OPSIZE));
+    }
+
+
+    if (patmHasImmsReferringPatch(pVM, pInstrGC))
+    {
+        pPatch->flags |= PATMFL_INT3_REPLACEMENT_BLOCK;
     }
 

trunk/src/VBox/VMM/PATM/PATMInternal.h

@@ -79 +79 @@
 #define PATMFL_EXTERNAL_JUMP_INSIDE         RT_BIT_64(33) /** A trampoline patch was created that jumps to an instruction in the patch block */
 #define PATMFL_CODE_REFERENCED              RT_BIT_64(34) /** patch block referenced (called, jumped to) by another patch. */
+
+/* Global flags, affect PATM behavior */
+#define PATMGFL_SEARCH_IMM_BACKWARD         RT_BIT_32(0)  /** search backward from priveledged insn for immediates referring inside patch */
 
 #define SIZEOF_NEARJUMP8                   2 //opcode byte + 1 byte relative offset
@@ -520 +523 @@
     STAMCOUNTER             StatFunctionLookupInsert;
     uint32_t                StatU32FunctionMaxSlotsUsed;
-    uint32_t                Alignment0; /**< Align the structure size on a 8-byte boundrary. */
+    uint32_t                uPATMFlags; 
 } PATM, *PPATM;