Changeset 104123 in vbox

Timestamp:

Mar 30, 2024 1:12:57 AM (8 months ago)

Author:

vboxsync

Message:

VMM/IEM: Avoid the two RTMemProtect calls in iemExecMemAllocatorFree on darwin. bugref:10370

Location:

trunk/src/VBox/VMM/VMMAll

Files:

• IEMAllN8veExecMem.cpp (modified) (3 diffs)
• IEMAllThrdRecompiler.cpp (modified) (1 diff)

trunk/src/VBox/VMM/VMMAll/IEMAllN8veExecMem.cpp

@@ -373 +373 @@
     AssertReturnVoid(cChunks >= 1);
 
+    Assert(!pVCpu->iem.s.pCurTbR3);
+
     /*
      * Decide how much to prune.  The chunk is is a multiple of two, so we'll be
@@ -424 +426 @@
             PIEMTB const pTb = pHdr->pTb;
             AssertPtr(pTb);
-            Assert((pTb->fFlags & IEMTB_F_TYPE_MASK) == IEMTB_F_TYPE_NATIVE);
-
-            uint32_t const cbBlock = RT_ALIGN_32(pTb->Native.cInstructions * sizeof(IEMNATIVEINSTR) + sizeof(*pHdr),
-                                                 IEMEXECMEM_ALT_SUB_ALLOC_UNIT_SIZE);
-            AssertBreakStmt(offChunk + cbBlock <= cbChunk, offChunk += IEMEXECMEM_ALT_SUB_ALLOC_UNIT_SIZE); /* paranoia */
-
-            iemTbAllocatorFree(pVCpu, pTb);
-
-            cbPruned += cbBlock;
-            offChunk += cbBlock;
+
+            /* We now have to check that this isn't a old freed header, given
+               that we don't invalidate the header upon free because of darwin
+               restrictions on executable memory (iemExecMemAllocatorFree).
+               This relies upon iemTbAllocatorFreeInner resetting TB members. */
+            if (   pTb->Native.paInstructions == (PIEMNATIVEINSTR)(pHdr + 1)
+                && (pTb->fFlags & IEMTB_F_TYPE_MASK) == IEMTB_F_TYPE_NATIVE)
+            {
+                uint32_t const cbBlock = RT_ALIGN_32(pTb->Native.cInstructions * sizeof(IEMNATIVEINSTR) + sizeof(*pHdr),
+                                                     IEMEXECMEM_ALT_SUB_ALLOC_UNIT_SIZE);
+                AssertBreakStmt(offChunk + cbBlock <= cbChunk, offChunk += IEMEXECMEM_ALT_SUB_ALLOC_UNIT_SIZE); /* paranoia */
+
+                iemTbAllocatorFree(pVCpu, pTb);
+
+                cbPruned += cbBlock;
+                offChunk += cbBlock;
+            }
+            else
+                offChunk += IEMEXECMEM_ALT_SUB_ALLOC_UNIT_SIZE;
         }
         else
@@ -713 +724 @@
             ASMBitClearRange(pbmAlloc, idxFirst, idxFirst + cReqUnits);
 
-#ifdef IEMEXECMEM_ALT_SUB_WITH_ALLOC_HEADER
+#if 0 /*def IEMEXECMEM_ALT_SUB_WITH_ALLOC_HEADER - not necessary, we'll validate the header in the pruning code. */
 # ifdef RT_OS_DARWIN
             int rc = RTMemProtect(pHdr, sizeof(*pHdr), RTMEM_PROT_WRITE | RTMEM_PROT_READ);

trunk/src/VBox/VMM/VMMAll/IEMAllThrdRecompiler.cpp

@@ -885 +885 @@
             iemExecMemAllocatorFree(pVCpu, pTb->Native.paInstructions,
                                     pTb->Native.cInstructions * sizeof(pTb->Native.paInstructions[0]));
+            pVCpu, pTb->Native.paInstructions = NULL; /* required by iemExecMemAllocatorPrune */
             break;
 #endif