Got basic tty driver & implemented Stack Smash Protector

defaults.mk

@@ -10,7 +10,7 @@ MAKE = make
 # Flags
 HOSTCCFLAGS = -Wall -Wextra -Wpedantic -Os -std=c17
 CCFLAGS = -Wall -Wextra -Wpedantic -Wno-pointer-arith\
-	 -ffreestanding -fno-stack-protector -fno-builtin -fno-pie -fcommon\
+	 -ffreestanding -fstack-protector -fno-builtin -fno-pie -fcommon\
 	 -O2 -std=c17 -nostdinc -nostdlib -z notext -march=i386 -m32
 LDFLAGS = -melf_i386
 ASFLAGS = 

kernel/include/kernel.h

@@ -1,6 +1,33 @@
 #ifndef _KERNEL_H
 #define _KERNEL_H
 
+// Null definition
+#define NULL	((void*)0)
+
+/*
+ * Variable arguments
+ */
+typedef void* va_list;
+#define va_start(ap, param) (void)((ap) = (char*)(&(param) + 1))
+#define va_end(ap) (void)((ap) = 0)
+#define va_arg(ap, type) (((type*)((ap) = ((ap) + sizeof(type))))[-1])
+
+/*
+ * Utility macros
+ */
+#define ARRAY_SIZE(_a)	(sizeof((_a)) / sizeof((_a)[0]))
+#define BIT(_n)		(1UL << (_n))
+#define BIT_MASK(_n)	(BIT(_n) - 1)
+#define ALIGN(_x, _a)	__ALIGN_MASK((_x), (typeof(_x))(_a) - 1)
+#define __ALIGN_MASK(_x, _m) (((_x) + (_m)) & ~(_m))
+#define container_of(_p, _t, _m) \
+	((_t*)((char*)(_p) - offsetof(_t, _m)))
+#define swap(_a, _b)	({ typeof(_a) _tmp = (_a); (_a) = (_b); (_b) = (_a); })
+#define min(_x, _y)	({ typeof(_x) __x = (_x); typeof(_y) __y = (_y); __x < __y ? __x : __y; })
+#define max(_x, _y)	({ typeof(_x) __x = (_x); typeof(_y) __y = (_y); __x > __y ? __x : __y; })
+#define ceil(_x, _y)	((((_x) + (_y)) (_y)) * (_y))
+#define floor(_x, _y)	((_x) - ((_x) % (_y)))
+
 /*
  * Attribute definitions
  */ 
@@ -20,18 +47,29 @@
 /*
  * Standard int types
  */
-// Unsigned
 typedef unsigned char	uint8_t;
 typedef unsigned short	uint16_t;
 typedef unsigned int	uint32_t;
 typedef unsigned long	uint64_t;
-// Signed
 typedef signed char	int8_t;
 typedef signed short	int16_t;
 typedef signed int	int32_t;
 typedef signed long	int64_t;
-// Size
 typedef uint32_t	size_t;
 typedef int32_t		ssize_t;
+typedef uint32_t	uintptr_t;
+typedef int32_t		intptr_t;
+
+/*
+ * Logging and errors
+ */
+// TODO: Logging with printk()
+// TODO: Log levels & pr_*() wrappers for printk()
+#define BUG()		(panic("BUG()"))
+#define WARN()		NULL
+#define BUG_ON(_e)	((_e) ? BUG() : NULL)
+#define WARN_ON(_e)	((_e) ? WARN() : NULL)
+// TODO: Write a panic()
+#define panic(_s)	while(1);
 
 #endif

kernel/include/tty.h

@@ -2,13 +2,15 @@
 #define _TTY_H
 
 /* VGA Text mode */
+#define VGA_ATTR(_fg, _bg)	((_fg) | ((_bg) << 4)
 #define VGA_WIDTH	80
 #define VGA_HEIGHT	25
 #define VGA_MEMORY	0xb8000
 
-int tty_init(void);
-int tty_write(char* buf, size_t len);
-int tty_putc(char c);
-int tty_puts(char* s);
+void tty_init(void);
+void tty_clear(void);
+void tty_setattr(uint8_t attr);
+void tty_putc(char c);
+void tty_puts(char* s);
 
 #endif

kernel/makefile

@@ -5,8 +5,8 @@ BIN = ./bin
 INC = ./include
 SRCS_C = $(wildcard $(SRC)/*.c)
 SRCS_S = $(wildcard $(SRC)/*.s)
-OBJS_C = $(patsubst $(SRC)/%.c, $(BIN)/%.o, $(SRCS_C))
-OBJS_S = $(patsubst $(SRC)/%.s, $(BIN)/%.o, $(SRCS_S))
+OBJS_C = $(patsubst $(SRC)/%.c, $(BIN)/%.c.o, $(SRCS_C))
+OBJS_S = $(patsubst $(SRC)/%.s, $(BIN)/%.s.o, $(SRCS_S))
 OUT = ./kernel.elf
 LINKER = ./linker.ld
 
@@ -15,11 +15,11 @@ all: $(OUT)
 $(OUT): $(OBJS_C) $(OBJS_S)
 	$(LD) $(LDFLAGS) -T$(LINKER) -o $@ $^
 
-$(BIN)/%.o: $(SRC)/%.c
+$(BIN)/%.c.o: $(SRC)/%.c
 	@mkdir -p $(dir $@)
 	$(CC) $(CCFLAGS) -I$(INC) -c -o $@ $^
 
-$(BIN)/%.o: $(SRC)/%.s
+$(BIN)/%.s.o: $(SRC)/%.s
 	@mkdir -p $(dir $@)
 	$(AS) $(ASFLAGS) -felf32 -o $@ $^
 

kernel/src/kernel.c

@@ -1,9 +1,13 @@
 #include <kernel.h>
 #include <tty.h>
 
+#define _hlt()	while (1) __asm__ volatile ("cli; hlt");
+
 __noreturn
 void kmain(void) {
 	tty_init();
-	printk("Hello, World!\n");
+	tty_puts("Hello, World!\n");
+
+	_hlt();
 }
 

kernel/src/ssp.c

@@ -0,0 +1,14 @@
+/*
+ * Stack Smash Protector
+ * Source: https://wiki.osdev.org/Stack_Smashing_Protector
+*/
+#include <kernel.h>
+
+// TODO: Make this randomized
+#define STACK_CHK_GUARD	0x27a1abd8
+
+uintptr_t __stack_chk_guard = STACK_CHK_GUARD;
+__noreturn void __stack_chk_fail(void) {
+	panic("Stack smashing detected!");
+}
+

kernel/src/tty.c

@@ -12,20 +12,52 @@ void tty_init(void) {
 	ctx.row = 0;
 	ctx.col = 0;
 	ctx.attr = 0x07;
-	ctx.buf = (u8*)VGA_MEMORY;
-
-	for (size_t y = 0; y < VGA_HEIGHT; y++) {
-		for (size_t x = 0; x < VGA_WIDTH; x++) {
-			size_t i = (y * VGA_WIDTH + x) * 2;
-			ctx.buf[i] = ' ';
-			ctx.buf[i + 1] = ctx.attr;
-		}
-	}
+	ctx.buf = (uint8_t*)VGA_MEMORY;
+	tty_clear();
 }
 
-int tty_write(char* buf, size_t len) {}
+void tty_clear(void) {
+	for (int i = 0; i < VGA_WIDTH * VGA_HEIGHT; i++) {
+		ctx.buf[i * 2] = ' ';
+		ctx.buf[i * 2 + 1] = ctx.attr;
+	}
+}
 
-int tty_putc(char c) {}
+void tty_setattr(uint8_t attr) {
+	ctx.attr = attr;
+}
 
-int tty_puts(char* s) {}
+// TODO:
+void tty_scroll(void) {
+	ctx.row = 0;
+	ctx.col = 0;
+	tty_clear();
+}
+
+void tty_putat(char c, size_t row, size_t col) {
+	size_t i = row * VGA_WIDTH + col;
+	ctx.buf[i * 2] = c;
+	ctx.buf[i * 2 + 1] = ctx.attr;
+}
+
+void tty_putc(char c) {
+	if (c == '\n') { 
+		ctx.col = 0;
+		ctx.row++;
+		if (ctx.row >= VGA_HEIGHT) tty_scroll();
+		return;
+	}
+
+	tty_putat(c, ctx.row, ctx.col++);
+	if (ctx.col >= VGA_WIDTH) {
+		ctx.col = 0;
+		ctx.row++;
+	}
+
+	if (ctx.row >= VGA_HEIGHT) tty_scroll();
+}
+
+void tty_puts(char* s) {
+	while (*s != '\0') tty_putc(*s++);
+}
 

makefile

@@ -14,7 +14,7 @@ clean:
 
 qemu:
 	qemu-system-x86_64\
-		-kernel ./kernel/kernel.elf
+		-kernel ./kernel/kernel.elf\
 		-m 256M -accel tcg -monitor stdio -net none\
 		-rtc base=localtime,clock=host,driftfix=slew\
 		-audiodev pipewire,id=audio0 -machine pcspk-audiodev=audio0