-/* Search the "hooked" memory regions for a region that ends after the given address. If the
- * address is invalid, return NULL. Else, return the first region found or the base region if no
- * region ends after the given address.
+/* Given an address, find the successor region. If the address is within a region, return that
+ * region. Input is an address, because the address may not have a region associated with it.
+ *
+ * Returns a region following or touching the given address. If address is invalid, NULL is
+ * returned, else the base region is returned if no region exists at or after the given address.
*/
struct v3_mem_region * v3_get_next_mem_region( struct v3_vm_info * vm, uint16_t core_id, addr_t guest_addr) {
- struct rb_node * n = vm->mem_map.mem_regions.rb_node;
- struct v3_mem_region * reg = NULL;
-
- // Keep going to the right in the tree while the address is greater than the current region's
- // end address.
- while (n) {
- reg = rb_entry(n, struct v3_mem_region, tree_node);
- if (guest_addr >= reg->guest_end) { // reg is [start,end)
- n = n->rb_right;
- } else {
- if ((core_id == reg->core_id) || (reg->core_id == V3_MEM_CORE_ANY)) {
- return reg;
- } else {
- n = n->rb_right;
+ struct rb_node * current_n = vm->mem_map.mem_regions.rb_node;
+ struct rb_node * successor_n = NULL; /* left-most node greater than guest_addr */
+ struct v3_mem_region * current_r = NULL;
+
+ /* current_n tries to find the region containing guest_addr, going right when smaller and left when
+ * greater. Each time current_n becomes greater than guest_addr, update successor <- current_n.
+ * current_n becomes successively closer to guest_addr than the previous time it was greater
+ * than guest_addr.
+ */
+
+ /* | is address, ---- is region, + is intersection */
+ while (current_n) {
+ current_r = rb_entry(current_n, struct v3_mem_region, tree_node);
+ if (current_r->guest_start > guest_addr) { /* | ---- */
+ successor_n = current_n;
+ current_n = current_n->rb_left;
+ } else {
+ if (current_r->guest_end > guest_addr) {
+ return current_r; /* +--- or --+- */
}
- }
+ current_n = current_n->rb_right; /* ---- | */
+ }
}
- // There is no registered region, so we check if it's a valid address in the base region
+ /* Address does not have its own region. Check if it's a valid address in the base region */
if (guest_addr >= vm->mem_map.base_region.guest_end) {
PrintError("%s: Guest Address Exceeds Base Memory Size (ga=%p), (limit=%p)\n",
