'mem' command shows memory usage of kernel heap now

implemented a malloc/free and memory manager (simplest possible implementation,
just allocating linearly and never freeing)

8 files changed, 141 insertions, 28 deletions

diff --git a/src/Makefile b/src/Makefile
index c256605..d8b279f 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -33,11 +33,11 @@ kernel.bin: kernel.elf
 kernel.sym: kernel.elf
 	$(OBJCOPY) --only-keep-debug kernel.elf kernel.sym
 
-kernel.elf: kernel/kernel.o kernel/kernel_asm.o kernel/console.o kernel/vgatext.o kernel/serial.o kernel/tasks.o hardware/port.o hardware/port_asm.o hardware/interrupts.o hardware/interrupts_asm.o hardware/pci.o drivers/driver.o drivers/hdi/ps2/keyboard.o drivers/hdi/ps2/mouse.o drivers/video/vga.o drivers/video/vga_font.o gui/widget.o gui/composite_widget.o gui/window.o gui/desktop.o gui/text_widget.o libc/string.o libc/stdlib.o libc/stdio.o libc/setjmp.o
+kernel.elf: kernel/kernel.o kernel/kernel_asm.o kernel/console.o kernel/vgatext.o kernel/serial.o kernel/memorymanagement.o kernel/tasks.o hardware/port.o hardware/port_asm.o hardware/interrupts.o hardware/interrupts_asm.o hardware/pci.o drivers/driver.o drivers/hdi/ps2/keyboard.o drivers/hdi/ps2/mouse.o drivers/video/vga.o drivers/video/vga_font.o gui/widget.o gui/composite_widget.o gui/window.o gui/desktop.o gui/text_widget.o libc/string.o libc/stdlib.o libc/stdio.o libc/setjmp.o
 	$(LD) -o kernel.elf -N -n -Ttext 0x8800 --oformat elf32-i386 \
 		kernel/kernel.o kernel/kernel_asm.o \
 		kernel/console.o kernel/vgatext.o kernel/serial.o \
-		kernel/tasks.o \
+		kernel/memorymanagement.o kernel/tasks.o \
 		hardware/port.o hardware/port_asm.o \
 		hardware/interrupts.o hardware/interrupts_asm.o \
 		hardware/pci.o \
@@ -72,6 +72,9 @@ kernel/vgatext.o: kernel/vgatext.c kernel/vgatext.h
 kernel/serial.o: kernel/serial.c kernel/serial.h
 	$(CC) $(CFLAGS) -c -o kernel/serial.o kernel/serial.c
 
+kernel/memorymanagement.o: kernel/memorymanagement.c kernel/memorymanagement.h
+	$(CC) $(CFLAGS) -c -o kernel/memorymanagement.o kernel/memorymanagement.c
+
 kernel/tasks.o: kernel/tasks.c kernel/tasks.h
 	$(CC) $(CFLAGS) -c -o kernel/tasks.o kernel/tasks.c
 
diff --git a/src/kernel/kernel.c b/src/kernel/kernel.c
index a9802e1..a6594f6 100644
--- a/src/kernel/kernel.c
+++ b/src/kernel/kernel.c
@@ -42,6 +42,7 @@ typedef struct {
 	vga_text_t vga_text;
 	driver_manager_t driver_manager;
 	task_manager_t task_manager;
+	memory_manager_t memory_manager;
 	vga_t vga;
 	mode_t mode;
 	mouse_t mouse;
@@ -60,6 +61,7 @@ static void refresh_screen( void );
 static void switch_to_graphics_mode( global_context_t *global_context );
 static void switch_to_text_mode( global_context_t *global_context );
 static void print_task_status( global_context_t *global_context );
+static void print_memory_status( global_context_t *global_context );
 
 // must be first entry in kernel.bin (0x8800) as stage 2 of
 // the boot loader expects the entry point to be here!
@@ -78,13 +80,25 @@ void kernel_main( void )
 	console_init( &console );
 	console_add_vga_text_output( &console, &global_context.vga_text );
 	console_add_serial_output( &console, &serial );
-	
+
 	// initialize the early console of the kernel
-	stdio_set_console( &console );
+	__stdio_set_console( &console );
 	puts( "Started early kernel console" );
 	// TODO: get those values somehow from the boot loader
 	printf( "Kernel code and data is at 0x%X, kernel stack at 0x%X\n", 0x8800, 0x90000 );
 
+	// initialize memory management first, we may need it
+	// TODO: get memupper from multiboot header (but this needs
+	// a multiboot compliant entry function first) or use BIOS
+	// functions to determine size of memory, for now assume we
+	// have at least, for now use the memory above 1 MB, 64 MB
+	// heap is enough for what we are doing in the kernel
+	memory_manager_init( &global_context.memory_manager, 0x100000, 0xFFFF );
+	__stdlib_set_memory_manager( &global_context.memory_manager );
+	printf( "Kernel heap at 0x%X, size 0x%X\n", 0x100000, 0xFFFF );
+	void *test = malloc( 2048 );
+	free( test );
+
 	// exit point in case of kernel panic, do this as soon as
 	// possible, as soon we have an early console we can croak on
 	if( setjmp( panic_jmp_buf ) > 0 ) {
@@ -211,7 +225,7 @@ static void handle_keyboard_event( keyboard_event_t *event, void *context )
 						} else if( strcmp( buf, "halt" ) == 0 ) {
 							longjmp( panic_jmp_buf, 0 );
 						} else if( strcmp( buf, "mem" ) == 0 ) {
-							// TODO: print memory usage
+							print_memory_status( global_context );
 						} else if( strcmp( buf, "task" ) == 0 ) {
 							print_task_status( global_context );
 						} else if( strcmp( buf, "driver" ) == 0 ) {
@@ -411,3 +425,17 @@ static void print_task_status( global_context_t *global_context )
 	}
 }
 
+static void print_memory_status( global_context_t *global_context )
+{
+	memory_manager_t *memory_manager = &global_context->memory_manager;
+
+	printf( "heap memory size: %d\n", memory_manager->size );
+	printf( "heap memory offset: 0x%X\n", memory_manager->offset );
+	printf( "heap memory in use: %d\n",
+		memory_manager->free_ptr - memory_manager->offset );
+	printf( "heap memory free: %d\n", 
+			memory_manager->size - ( memory_manager->free_ptr - memory_manager->offset ) - 1 );
+	
+}
+
+
diff --git a/src/kernel/memorymanagement.c b/src/kernel/memorymanagement.c
new file mode 100644
index 0000000..dc2d160
--- /dev/null
+++ b/src/kernel/memorymanagement.c
@@ -0,0 +1,40 @@
+#include "memorymanagement.h"
+
+#include "string.h"
+
+#include "kernel.h"
+
+void memory_manager_init( memory_manager_t *memory_manager, size_t offset, size_t size )
+{
+	memset( memory_manager, 0, sizeof( memory_manager_t ) );
+
+	memory_manager->offset = offset;
+	memory_manager->size = size;
+	memory_manager->free_ptr = offset;
+}
+
+void *memory_manager_allocate( memory_manager_t *memory_manager, size_t size )
+{
+	void *p = NULL;
+
+	if( memory_manager->free_ptr - memory_manager->offset + size > memory_manager->size ) {
+		kernel_panic( "Heap allocation out of memory (requested %d bytes, available %d)",
+			size, size - ( memory_manager->free_ptr - memory_manager->offset ) - 1 );
+	}
+
+	p = (void *)memory_manager->free_ptr;
+	memory_manager->free_ptr += size;
+
+	return p;
+}
+
+void memory_manager_deallocate( memory_manager_t *memory_manager, void **p )
+{
+	if( *p == NULL ) {
+		kernel_panic( "Double free of pointer 0x%X in heap", *p );
+	}
+
+	*p = NULL;
+}
+
+
diff --git a/src/kernel/memorymanagement.h b/src/kernel/memorymanagement.h
new file mode 100644
index 0000000..16f0b29
--- /dev/null
+++ b/src/kernel/memorymanagement.h
@@ -0,0 +1,16 @@
+#ifndef MEMORYMANAGEMENT_H
+#define MEMORYMANAGEMENT_H
+
+#include "stddef.h"
+
+typedef struct {
+	size_t offset;
+	size_t size;
+	uint32_t free_ptr;
+} memory_manager_t;
+
+void memory_manager_init( memory_manager_t *memory_manager, size_t offset, size_t size );
+void *memory_manager_allocate( memory_manager_t *memory_manager, size_t size );
+void memory_manager_deallocate( memory_manager_t *memory_manager, void **p );
+
+#endif // MEMORYMANAGEMENT_H
diff --git a/src/libc/stdio.c b/src/libc/stdio.c
index 1d53f7a..07a047e 100644
--- a/src/libc/stdio.c
+++ b/src/libc/stdio.c
@@ -3,16 +3,16 @@
 #include "stdlib.h"
 #include "string.h"
 
-console_t *global_console = NULL;
+console_t *stdio_console = NULL;
 
 int puts( const char *s )
 {
-	if( global_console == NULL ) {
+	if( stdio_console == NULL ) {
 		return EOF;
 	}
 	
-	console_put_string( global_console, s );
-	console_put_newline( global_console );
+	console_put_string( stdio_console, s );
+	console_put_newline( stdio_console );
 	
 	return 1;
 }
@@ -33,34 +33,34 @@ int vprintf( const char *format, va_list args )
 	const char *s = format;
 	int n = 0;
 
-	if( global_console == NULL ) {
+	if( stdio_console == NULL ) {
 		return -1;
 	}
 	
 	while( *s != '\0' ) {
 		switch( *s ) {
 			case '\n':
-				console_put_newline( global_console );
+				console_put_newline( stdio_console );
 				n++;
 				break;
 			
 			case '%':
 				s++;
 				if( *s == '\0' ) {
-					console_put_string( global_console, "<truncated % found at end of format string>" );
-					console_put_newline( global_console );
+					console_put_string( stdio_console, "<truncated % found at end of format string>" );
+					console_put_newline( stdio_console );
 					return -1;
 				}
 				
 				switch( *s ) {
 					case '%':
-						console_put_char( global_console, '%' );
+						console_put_char( stdio_console, '%' );
 						break;
 						
 					case 'X': {
 						char buf[19];
 						itoa( va_arg( args, int ), (char *)buf, 16 );
-						console_put_string( global_console, buf );
+						console_put_string( stdio_console, buf );
 						n += strlen( buf );
 						}
 						break;
@@ -68,30 +68,30 @@ int vprintf( const char *format, va_list args )
 					case 'd': {
 						char buf[19];
 						itoa( va_arg( args, int ), (char *)buf, 10 );
-						console_put_string( global_console, buf );
+						console_put_string( stdio_console, buf );
 						n += strlen( buf );
 						}
 						break;
 
 					case 'c':
-						console_put_char( global_console, va_arg( args, int ) );
+						console_put_char( stdio_console, va_arg( args, int ) );
 						break;
 						
 					case 's':
-						console_put_string( global_console, va_arg( args, const char * ) );
+						console_put_string( stdio_console, va_arg( args, const char * ) );
 						break;
 
 					default:
-						console_put_string( global_console, "<illegal format string %" );
-						console_put_char( global_console, *s );
-						console_put_string( global_console, ">" );
-						console_put_newline( global_console );
+						console_put_string( stdio_console, "<illegal format string %" );
+						console_put_char( stdio_console, *s );
+						console_put_string( stdio_console, ">" );
+						console_put_newline( stdio_console );
 				}
 				
 				break;				
 			
 			default:
-				console_put_char( global_console, *s );
+				console_put_char( stdio_console, *s );
 				n++;
 		}
 		s++;
@@ -100,7 +100,7 @@ int vprintf( const char *format, va_list args )
 	return n;
 }
 
-void stdio_set_console( console_t *console )
+void __stdio_set_console( console_t *console )
 {
-	global_console = console;
+	stdio_console = console;
 }
diff --git a/src/libc/stdio.h b/src/libc/stdio.h
index bc7fac0..dbf7ac7 100644
--- a/src/libc/stdio.h
+++ b/src/libc/stdio.h
@@ -9,12 +9,10 @@
 
 #define EOF (-1)
 
-extern console_t *global_console;
-
 int puts( const char *s );
 int printf( const char *format, ... );
 int vprintf( const char *format, va_list args );
 
-void stdio_set_console( console_t *console );
+void __stdio_set_console( console_t *console );
 
 #endif //STDIO_H
diff --git a/src/libc/stdlib.c b/src/libc/stdlib.c
index 46bdce8..9150431 100644
--- a/src/libc/stdlib.c
+++ b/src/libc/stdlib.c
@@ -45,4 +45,23 @@ char *itoa( int v, char *s, int base )
 	
 	return s;
 }
+
+// TODO: we should have a global memory manager and one per
+// user process later
+static memory_manager_t *stdlib_memory_manager = NULL;
   
+void *malloc( size_t size )
+{
+	return memory_manager_allocate( stdlib_memory_manager, size );
+}
+
+void free( void *p )
+{
+	memory_manager_deallocate( stdlib_memory_manager, &p );
+}
+
+void __stdlib_set_memory_manager( memory_manager_t *memory_manager )
+{
+	stdlib_memory_manager = memory_manager;
+}
+
diff --git a/src/libc/stdlib.h b/src/libc/stdlib.h
index 331012e..ff6b67f 100644
--- a/src/libc/stdlib.h
+++ b/src/libc/stdlib.h
@@ -1,6 +1,15 @@
 #ifndef STDLIB_H
 #define STDLIB_H
 
+#include "stddef.h"
+
+#include "memorymanagement.h"
+
 char *itoa( int v, char *s, int base );
 
+void *malloc( size_t size );
+void free( void *p );
+
+void __stdlib_set_memory_manager( memory_manager_t *memory_manager );
+
 #endif // STDLIB_H