virtual_mm: Identity map the first 8MiB

1 files changed, 52 insertions, 0 deletions

diff --git a/kernel/mm/virtual_mm/pages.cc b/kernel/mm/virtual_mm/pages.cc
new file mode 100644
index 0000000..0f27087
--- /dev/null
+++ b/kernel/mm/virtual_mm/pages.cc
@@ -0,0 +1,52 @@
+/*
+ * bubbl
+ * Copyright (C) 2025  Raghuram Subramani <raghus2247@gmail.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <kernel/halt.h>
+#include <libk/stdio.h>
+#include <mm/physical_mm.h>
+#include <mm/virtual_mm.h>
+#include <stdbool.h>
+#include <stdint.h>
+
+namespace VirtualMM
+{
+
+void *
+alloc_pages(uint32_t n_pages)
+{
+  uint32_t starting_address = (uint32_t) find_free_addresses(n_pages);
+  if (starting_address == 0)
+    return 0;
+
+  for (uint32_t i = 0; i < n_pages; i++) {
+    void *virtual_address = (void *) (starting_address + (i * PAGE_SIZE));
+    void *physical_address = PhysicalMM::allocate_block();
+    map_page(physical_address, virtual_address);
+  }
+
+  return (void *) starting_address;
+}
+
+void
+free_pages(void *starting_address, uint32_t n_pages)
+{
+  for (uint32_t i = 0; i < n_pages; i++)
+    unmap_page((void *) (((uint32_t) starting_address) + (i * 4096)));
+}
+
+}