Free process heap on exit. Display free memory size on status.

include/kalloc.h

@@ -21,5 +21,6 @@ void *kalloc();
 void kfree(void *page);
 void *kalloc1k();
 void kfree1k(void *page);
+uint32_t get_free_memory_size(void);
 
 #endif

include/proc.h

@@ -84,6 +84,7 @@ void proc_init(void);
 struct Process *proc_create(void);
 void proc_free(struct Process *proc);
 void proc_expand_memory(struct Process *proc, int page_count);
+void proc_shrink_memory(struct Process *proc, int page_count);
 bool proc_load(struct Process *proc, char **proc_image, int page_count);
 void proc_switch(struct Process *proc);
 

kernel/kalloc.c

@@ -77,6 +77,27 @@ void kfree1k(void *page)
 	free_list_1k = page_list_prepend(free_list_1k, page);
 }
 
+uint32_t get_free_memory_size(void) {
+	uint32_t result = 0;
+	struct PageList *current_page = NULL;
+
+	/* iterate over free 1k pages */
+	current_page = free_list_1k;
+	while (current_page != NULL) {
+		result += 1024;
+		current_page = current_page->next;
+	}
+
+	/* iterate over free 4k pages */
+	current_page = free_list_4k;
+	while (current_page != NULL) {
+		result += 4096;
+		current_page = current_page->next;
+	}
+
+	return result;
+}
+
 /*
  * page_list_prepend adds the given page to the beginning of the page list
  * and returns the address of the new page list.

kernel/monitor/mon_status.c

@@ -1,4 +1,5 @@
 #include <monitor.h>
+#include <kalloc.h>
 #include <klib.h>
 #include <lib/string.h>
 #include <system.h>
@@ -12,6 +13,7 @@ static void print_control_register(void);
 static void print_cpsr_status(void);
 static void print_supervisor_sp(void);
 static void print_irq_sp(void);
+static void print_free_memory(void);
 static uint32_t get_bits(uint32_t n, uint32_t bitmask);
 
 /* mon_status displays information about the current status of system. */
@@ -28,6 +30,7 @@ int mon_status(int argc, char **argv)
 	print_cpsr_status();
 	print_supervisor_sp();
 	print_irq_sp();
+	print_free_memory();
 
 	return 0;
 }
@@ -131,6 +134,12 @@ static void print_irq_sp(void)
 		irq_stack_start - irq_stack_current);
 }
 
+static void print_free_memory(void)
+{
+	uint32_t free_memory_size = get_free_memory_size();
+	kprintf("free memory size: %d (bytes)\n", free_memory_size);
+}
+
 static uint32_t get_bits(uint32_t n, uint32_t bitmask)
 {
 	uint32_t result = 0;

kernel/proc.c

@@ -73,6 +73,7 @@ void proc_free(struct Process *proc)
 {
 	kfree(proc->kernel_stack);
 	kfree(proc->user_stack);
+	proc_shrink_memory(proc, proc->heap_size / PAGE_SIZE);
 	free_vm_page_tables(proc->vm);
 }
 
@@ -93,6 +94,24 @@ void proc_expand_memory(struct Process *proc, int page_count)
 	}
 }
 
+void proc_shrink_memory(struct Process *proc, int page_count)
+{
+	int i = 0;
+
+	for (i = 0; i < page_count; i++) {
+		uint32_t virtual_addr = proc->heap_size - PAGE_SIZE;
+		uint32_t physical_addr = resolve_physical_address(proc->vm,
+								  virtual_addr);
+		uint32_t kernel_addr = P2V(physical_addr);
+		kfree((void *) kernel_addr);
+
+		proc->heap_size -= PAGE_SIZE;
+		if (proc->heap_size == 0) {
+			break;
+		}
+	}
+}
+
 bool proc_load(struct Process *proc, char **proc_image, int page_count)
 {
 	int prog_header_offset = 0;