ptos: pool: Add freeing of allocated memory

Signed-off-by: Chloe M <chloe@mensia.org>

service/ptos/ex/pool.c

@@ -268,6 +268,41 @@ ExAllocatePoolWithTag(POOL_TYPE Type, USIZE ByteCount, ULONG Tag)
     return Base;
 }
 
+VOID
+ExFreePoolWithTag(VOID *Ptr, ULONG Tag)
+{
+    POOL_HEADER *Header;
+    POOL_PAGE *Page;
+    USHORT BitOff, BitMax;
+
+    if (Ptr == NULL) {
+        return;
+    }
+
+    Header = PTR_NOFFSET(Ptr, sizeof(POOL_HEADER));
+    if (Header->Tag != Tag) {
+        KeBugCheck(
+            BUGCHECK_MISC,
+            "tag does not match pool header\n"
+        );
+    }
+
+    Page = Header->Page;
+    if (Page == NULL) {
+        KeBugCheck(
+            BUGCHECK_MISC,
+            "attempted free on malformed header\n"
+        );
+    }
+
+    BitMax = Header->SizeBytes / Header->Gran;
+    BitMax *= 8;
+
+    for (BitOff = Header->BitBase; BitOff < BitMax; ++BitOff) {
+        CLRBIT(&Page->Bitmap, BitOff);
+    }
+}
+
 VOID
 ExPoolRegionInit(POOL_REGION *Region)
 {

service/ptos/head/ex/pool.h

@@ -89,6 +89,14 @@ typedef struct {
  */
 VOID ExPoolRegionInit(POOL_REGION *Region);
 
+/*
+ * Free a pool with an associated tag
+ *
+ * @Ptr:  Base of memory to free
+ * @Tag:  Tag associated with allocated memory
+ */
+VOID ExFreePoolWithTag(VOID *Ptr, ULONG Tag);
+
 /*
  * Allocate a memory pool of a specific type and assign a tag
  * to it for verifying frees among other debugging needs.