3 files changed, 76 insertions, 21 deletions

diff --git a/kernel/memory/paging.c b/kernel/memory/paging.c
index 2cc5b7e..ec3c5c7 100644
--- a/kernel/memory/paging.c
+++ b/kernel/memory/paging.c
@@ -736,6 +736,9 @@ void *mem_mapaddr(mem_ctx_t ctx, void *phys, void *virt, size_t len,
 	if (virt == NULL)
 		return NULL;
 
+	if (virtaddr_take(&ctx->virtctx, virt, pages))
+		return NULL;
+
 	assert((uint64_t)virt % PAGE_SIZE == 0,
 		   "mem_mapaddr: vitural address not page aligned");
 
@@ -761,6 +764,9 @@ void *kmapuseraddr(mem_ctx_t ctx, const void *usrADDR, size_t len)
 	if (vADDR == NULL)
 		return NULL;
 
+	if (virtaddr_take(&kernel_mem_ctx->virtctx, vADDR, npages))
+		return NULL;
+
 	assert((size_t)vADDR % PAGE_SIZE == 0,
 		   "kmapuseraddr: vitural address not page aligned");
 
@@ -847,6 +853,9 @@ void *mem_alloc_pages_at(mem_ctx_t ctx, size_t count, void *virt,
 	struct phys_page_slice prev_phys_block = PHYS_PAGE_SLICE_NULL;
 	struct phys_page_slice phys_pages;
 
+	if (virtaddr_take(&ctx->virtctx, virt, count))
+		return NULL;
+
 	while (pages_needed > 0) {
 		phys_pages = alloc_phys_page_withextra(pages_needed);
 		if (phys_pages.pagestart == NULL) {
diff --git a/kernel/memory/virtalloc.c b/kernel/memory/virtalloc.c
index cbde9b4..863959e 100644
--- a/kernel/memory/virtalloc.c
+++ b/kernel/memory/virtalloc.c
@@ -1,5 +1,7 @@
+#include "lib/kio.h"
 #include <lib.h>
 #include <comus/memory.h>
+#include <stdint.h>
 
 #include "virtalloc.h"
 
@@ -177,32 +179,68 @@ void *virtaddr_alloc(struct virt_ctx *ctx, int n_pages)
 		if (node->is_alloc)
 			continue;
 
-		if (length >= n_length) {
-			struct virt_addr_node *new = get_node(ctx);
-			if (node->prev != NULL) {
-				node->prev->next = new;
-			} else {
-				ctx->start_node = new;
-			}
-			new->next = node;
-			new->prev = node->prev;
-			node->prev = new;
-			new->start = node->start;
-			new->end = new->start + n_length;
-			node->start = new->end;
-			new->is_alloc = true;
-			new->is_used = true;
-			new->next = node;
-			void *mem = (void *)new->start;
-			merge_back(ctx, new);
-			merge_forward(ctx, new);
-			return mem;
-		}
+		if (length < n_length)
+			continue;
+
+		return (void*)node->start;
 	}
 
 	return NULL;
 }
 
+int virtaddr_take(struct virt_ctx *ctx, const void *virt, int n_pages)
+{
+	if (n_pages < 1)
+		return 0;
+
+	long n_length = n_pages * PAGE_SIZE;
+	struct virt_addr_node *node = ctx->start_node;
+
+	for (; node != NULL; node = node->next) {
+		if (node->is_alloc)
+			continue;
+
+		if (node->start > (uintptr_t)virt ||
+			node->end < (uintptr_t)virt + n_length)
+			continue;
+
+		// create new node on left
+		if (node->start < (uintptr_t) virt) {
+			struct virt_addr_node *left = get_node(ctx);
+			left->next = node;
+			left->prev = node->prev;
+			left->start = node->start;
+			left->end = (uintptr_t) virt;
+			left->is_used = true;
+			left->is_alloc = false;
+			node->prev->next = left;
+			node->prev = left;
+		}
+
+		// create new node on right
+		if (node->end > (uintptr_t) virt + n_length) {
+			struct virt_addr_node *right = get_node(ctx);
+			right->prev = node;
+			right->next = node->next;
+			right->start = (uintptr_t) virt + n_length;
+			right->end = node->end;
+			right->is_used = true;
+			right->is_alloc = false;
+			node->next->prev = right;
+			node->next = right;
+		}
+
+		node->start = (uintptr_t) virt;
+		node->end = node->start + n_length;
+		node->is_alloc = true;
+		node->is_used = true;
+
+		return 0;
+	}
+
+	return 1;
+}
+
 long virtaddr_free(struct virt_ctx *ctx, const void *virtaddr)
 {
 	if (virtaddr == NULL)
diff --git a/kernel/memory/virtalloc.h b/kernel/memory/virtalloc.h
index 9a94208..5033242 100644
--- a/kernel/memory/virtalloc.h
+++ b/kernel/memory/virtalloc.h
@@ -65,6 +65,14 @@ int virtaddr_clone(struct virt_ctx *old, struct virt_ctx *new);
 void *virtaddr_alloc(struct virt_ctx *ctx, int pages);
 
 /**
+ * Take (yoink) a predefined virtual address of length x pages
+ * @param virt - the start of the vitural address to take
+ * @param pages - x pages
+ * @returns 0 on success, 1 on err
+ */
+int virtaddr_take(struct virt_ctx *ctx, const void *virt, int pages);
+
+/**
  * Free the virtual address from virtaddr_alloc
  * @param virtaddr - the addr to free
  * @returns number of pages used for virtaddr