Implement flexpage lifecycle management

Adds creation and destruction functions for flexpages, which are
software abstractions representing contiguous physical memory regions
with hardware-enforced protection attributes. These primitives will be
used by higher-level memory space management to construct per-task
memory views for PMP-based isolation.

Function naming follows kernel conventions to reflect that these
operations manage abstract memory protection objects rather than
just memory allocation.

Author: HeatCrab

Makefile

@@ -17,7 +17,7 @@ include arch/$(ARCH)/build.mk
 INC_DIRS += -I $(SRC_DIR)/include \
             -I $(SRC_DIR)/include/lib
 
-KERNEL_OBJS := timer.o mqueue.o pipe.o semaphore.o mutex.o logger.o error.o syscall.o task.o main.o
+KERNEL_OBJS := timer.o mqueue.o pipe.o semaphore.o mutex.o logger.o error.o syscall.o task.o memprot.o main.o
 KERNEL_OBJS := $(addprefix $(BUILD_KERNEL_DIR)/,$(KERNEL_OBJS))
 deps += $(KERNEL_OBJS:%.o=%.o.d)
 

include/sys/memprot.h

@@ -63,14 +63,31 @@ typedef struct {
  * DECLARE_MEMPOOL_FROM_SYMBOLS uses token concatenation to construct
  * linker symbol names automatically.
  */
-#define DECLARE_MEMPOOL(name_, start_, end_, flags_, tag_) \
-    { \
-        .name = (name_), \
-        .start = (uintptr_t)(start_), \
-        .end = (uintptr_t)(end_), \
-        .flags = (flags_), \
-        .tag = (tag_), \
+#define DECLARE_MEMPOOL(name_, start_, end_, flags_, tag_)           \
+    {                                                                \
+        .name = (name_), .start = (uintptr_t) (start_),              \
+        .end = (uintptr_t) (end_), .flags = (flags_), .tag = (tag_), \
     }
 
-#define DECLARE_MEMPOOL_FROM_SYMBOLS(name_, sym_base_, flags_, tag_) \
-    DECLARE_MEMPOOL((name_), &(sym_base_##_start), &(sym_base_##_end), (flags_), (tag_))
+#define DECLARE_MEMPOOL_FROM_SYMBOLS(name_, sym_base_, flags_, tag_)   \
+    DECLARE_MEMPOOL((name_), &(sym_base_##_start), &(sym_base_##_end), \
+                    (flags_), (tag_))
+
+/* Flexpage Management Functions */
+
+/* Creates and initializes a new flexpage.
+ * @base : Physical base address
+ * @size : Size in bytes
+ * @rwx : Permission bits
+ * @priority : Eviction priority
+ * Returns pointer to created flexpage, or NULL on failure.
+ */
+fpage_t *mo_fpage_create(uint32_t base,
+                         uint32_t size,
+                         uint32_t rwx,
+                         uint32_t priority);
+
+/* Destroys a flexpage.
+ * @fpage : Pointer to flexpage to destroy
+ */
+void mo_fpage_destroy(fpage_t *fpage);

kernel/memprot.c

@@ -0,0 +1,44 @@
+/* Memory Protection Management
+ *
+ * Provides allocation and management functions for flexpages, which are
+ * software abstractions representing contiguous physical memory regions with
+ * hardware-enforced protection attributes.
+ */
+
+#include <lib/libc.h>
+#include <lib/malloc.h>
+#include <sys/memprot.h>
+
+/* Creates and initializes a flexpage */
+fpage_t *mo_fpage_create(uint32_t base,
+                         uint32_t size,
+                         uint32_t rwx,
+                         uint32_t priority)
+{
+    fpage_t *fpage = malloc(sizeof(fpage_t));
+    if (!fpage)
+        return NULL;
+
+    /* Initialize all fields */
+    fpage->as_next = NULL;
+    fpage->map_next = NULL;
+    fpage->pmp_next = NULL;
+    fpage->base = base;
+    fpage->size = size;
+    fpage->rwx = rwx;
+    fpage->pmp_id = 0; /* Not loaded into PMP initially */
+    fpage->flags = 0;  /* No flags set initially */
+    fpage->priority = priority;
+    fpage->used = 0; /* Not in use initially */
+
+    return fpage;
+}
+
+/* Destroys a flexpage */
+void mo_fpage_destroy(fpage_t *fpage)
+{
+    if (!fpage)
+        return;
+
+    free(fpage);
+}