ptos: vm: Initialize valloc range + zero pagemap lvls

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

service/ptos/mm/vm.c

@@ -7,9 +7,22 @@
  */
 
 #include <mm/vm.h>
+#include <mm/pm.h>
+#include <ex/trace.h>
 #include <hal/page.h>
+#include <hal/mmu.h>
+#include <ke/bugcheck.h>
 #include <ptdef.h>
 
+#define DTRACE(Fmt, ...) \
+    TRACE("[ VM ]: " Fmt, ##__VA_ARGS__)
+
+/*
+ * Number of pages we start with that can be valloc'd
+ * total.
+ */
+#define INITIAL_VALLOC_PAGES 128
+
 /* Use to safely convert page size */
 #define PAGE_SIZE(PS)                \
     ((PS) >= NELEM(PageSizeTable))   \
@@ -21,6 +34,9 @@ static USIZE PageSizeTable[] = {
     [PAGESIZE_4K] = 0x1000
 };
 
+/* Bump pointer */
+static UPTR VallocBump = VALLOC_BASE;
+
 PT_STATUS MmUnmapRange(MMU_VAS *Vas, const MM_RANGE *Range, MMU_PAGESIZE PageSize)
 {
     PT_STATUS Status;
@@ -86,3 +102,40 @@ MmMapRange(MMU_VAS *Vas, const MM_RANGE *Range, MM_PROT Prot, MMU_PAGESIZE PageS
 
     return STATUS_SUCCESS;
 }
+
+VOID
+MmVmInit(VOID)
+{
+    PT_STATUS Status;
+    MMU_VAS VasCurrent;
+    UPTR VirtualStart;
+    UPTR VirtualEnd, Off;
+    UPTR PhysicalBase;
+    USIZE NumPages;
+    MM_PFN Pfn;
+
+    HalMmuReadVas(&VasCurrent);
+    VirtualStart = VallocBump;
+    VallocBump += INITIAL_VALLOC_PAGES * PAGESIZE;
+    VirtualEnd = VallocBump;
+    NumPages = (VirtualEnd - VirtualStart) / PAGESIZE;
+
+    for (Off = 0; Off < NumPages * PAGESIZE; Off += PAGESIZE) {
+        Pfn = MmRequestFrame();
+        PhysicalBase = PFN_TO_ADDRESS(Pfn);
+
+        Status = HalMmuMapPage(
+            &VasCurrent,
+            VirtualStart + Off,
+            PhysicalBase + Off,
+            PAGE_READ | PAGE_WRITE,
+            PAGESIZE_4K
+        );
+
+        if (PT_ERROR(Status)) {
+            KeBugCheck(BUGCHECK_OOM, "failed to map valloc pages\n");
+        }
+    }
+
+    DTRACE("initialized %d valloc pages\n", NumPages);
+}