sp1: vm: Add function to unmap vm regions

Signed-off-by: Ian Moffett <ian@mirocom.org>

usr/src/sp1/common/mm/vm_map.c

@@ -51,15 +51,33 @@ mm_vm_map(struct mmu_vfr *vfr, struct vm_map *mapping, int prot)
     for (size_t i = 0; i < len; i += gran) {
         status = mu_mmu_map(vfr, vma + i, pma + i, prot, mapping->ps);
 
-        /*
-         * TODO: We need to clean up here instead of leaving a big hole
-         *       when this fails.
-         */
+        /* Destroy what we created on failure */
         if (status != STATUS_SUCCESS) {
-            pr_trace("mapping failed, leaked %d bytes\n", len);
+            mm_vm_unmap(vfr, mapping);
             return status;
         }
     }
 
     return STATUS_SUCCESS;
 }
+
+status_t
+mm_vm_unmap(struct mmu_vfr *vfr, struct vm_map *mapping)
+{
+    size_t gran, len;
+    uintptr_t vma;
+
+    if (vfr == NULL || mapping == NULL) {
+        return STATUS_INVALID_PARAM;
+    }
+
+    gran = GRAN(mapping->ps);
+    vma = ALIGN_DOWN(mapping->vma_base, gran);
+    len = ALIGN_UP(len + (len & (gran - 1)), gran);
+
+    for (size_t i = 0; i < len; i += gran) {
+        mu_mmu_unmap(vfr, vma + i, mapping->ps);
+    }
+
+    return STATUS_SUCCESS;
+}

usr/src/sp1/head/mm/vm.h

@@ -24,6 +24,8 @@
  * @vma_base: Virtual memory base
  * @pma_base: Physical memory base
  * @length:   Number of bytes to map
+ *
+ * XXX: `pma_base' is unused when unmapping regions
  */
 struct vm_map {
     pagesize_t ps;
@@ -49,6 +51,14 @@ struct vm_map {
  */
 status_t mm_vm_map(struct mmu_vfr *vfr, struct vm_map *mapping, int prot);
 
+/*
+ * Destroy a virtual memory mapping
+ *
+ * @vfr:  Virtual fuck region to unmap within
+ * @mapping: Mapping to destroy
+ */
+status_t mm_vm_unmap(struct mmu_vfr *vfr, struct vm_map *mapping);
+
 /*
  * Initialize the virtual memory management
  */