basic vmm_alloc structure

kernel/src/vmm.c

@@ -0,0 +1,49 @@
+#include "kernel.h"
+#include <errno.h>
+#include <isr.h>
+#include <limits.h>
+#include <paging.h>
+#include <pmm.h>
+#include <types.h>
+
+// allocates set number of pages at address provided
+// if address is NULL address is chosen internaly
+int vmm_alloc(void** vaddr, uint64_t count, uint64_t flags) {
+	if (flags == 0) {
+		flags = PTE_FLAG_PRESENT | PTE_FLAG_WRITE | PTE_FLAG_NOEXEC;
+	}
+
+	uint64_t* pml4 = pag_get_pml4();
+	for (uint64_t i = 0; i < count; i++) {
+		uint64_t* pte = pag_get_pte(pml4, vaddr);
+		if (!IS_ERR(pte) && (*pte & PTE_FLAG_PRESENT)) {
+			// TODO actualy handle conflict
+			return EEXIST;
+		}
+	}
+
+	for (uint64_t i = 0; i < count; i++) {
+		void* paddr = pmm_alloc();
+		int pag_map_ret =
+		    pag_map(pml4, (void*)(((size_t)vaddr) * i * PAGE_SIZE),
+			    paddr, flags);
+		if (pag_map_ret != SUCCESS) {
+			if (i != 0) {
+				for (i -= 1; i != UINT64_MAX; i--) {
+					if (pag_unmap(pml4,
+						      (void*)(((size_t)vaddr) *
+							      i * PAGE_SIZE)) !=
+					    SUCCESS) {
+						panic(NULL,
+						      "failed to unmap "
+						      "previously mapped "
+						      "page. %s:%d",
+						      __FILE_NAME__, __LINE__);
+					}
+				}
+			}
+			return pag_map_ret;
+		}
+	}
+	return SUCCESS;
+}