use ELF for kernel

11 files changed, 188 insertions, 87 deletions

diff --git a/.gitignore b/.gitignore
index 273eb2f..6b1ec60 100644
--- a/.gitignore
+++ b/.gitignore
@@ -2,8 +2,8 @@
 *.o
 *.d
 *.img
-*.map
 *.dis.asm
+*.elf
 .version-*
 bx_enh_dbg.ini
 stage3/isr.asm
diff --git a/Makefile b/Makefile
index 666898c..eea6f87 100644
--- a/Makefile
+++ b/Makefile
@@ -9,8 +9,15 @@ override CFLAGS += \
 	-nostartfiles \
 	-nodefaultlibs \
 	-Wall \
-	-Wextra \
-	-MMD
+	-Wextra
+
+override LDFLAGS += --no-warn-rwx-segment
+
+ifneq "$(DEBUG)" "0"
+	override CFLAGS += -g -fno-omit-frame-pointer -DDEBUG
+	override LDFLAGS += -g
+	override NASMFLAGS_KERNEL += -g
+endif
 
 STAGE3_C = \
 	stage3/init.o \
@@ -44,41 +51,42 @@ STAGE3 = $(STAGE3_C) \
 	stage3/watchdog.o
 
 PAD_BOUNDARY = pad() { truncate -s $$(echo "($$(du -b $$1 | cut -f1)+$$2-1)/$$2*$$2" | bc) $$1; }; pad
-DISAS = objdump -b binary -D -M intel -m i386:x86-64 stage3.bin --adjust-vma 0x9000
+DISAS = objdump -D -M intel -j .text stage3.elf
 
-cuddles.img: stage1.bin stage2.bin stage3.bin fs.tar
-	cat stage{1,2,3}.bin fs.tar > cuddles.img
+cuddles.img: stage1.bin stage23.bin fs.tar
+	cat stage{1,23}.bin fs.tar > cuddles.img
 	$(PAD_BOUNDARY) cuddles.img 1048576
 
-stage1.bin: stage1/main.asm stage1/print.asm stage2.bin stage3.bin
-	nasm -f bin stage1/main.asm -o stage1.bin \
-		-dKSIZE=$$(du -cb stage{2,3}.bin | tail -n1 | cut -f1)
+stage1.bin: stage1/main.asm stage1/print.asm stage23.bin
+	nasm $(NASMFLAGS_BOOT) -f bin stage1/main.asm -o stage1.bin \
+		-dKSIZE=$$(du -cb stage23.bin | tail -n1 | cut -f1)
+
+stage23.bin: stage2.bin stage3.elf
+	cat stage2.bin stage3.elf > stage23.bin
+	$(PAD_BOUNDARY) stage23.bin 512
 
 stage2.bin: stage2/main.asm stage2/mmap.asm stage2/paging.asm stage2/vesa.asm stage1/print.asm
-	nasm -f bin stage2/main.asm -o stage2.bin
-	truncate -s 4608 stage2.bin
+	nasm $(NASMFLAGS_BOOT) -f bin stage2/main.asm -o stage2.bin
 
-stage3.bin fs/dbg/kernel.map &: $(STAGE3) stage3.ld
-	mkdir -p fs/dbg/
-	ld $(STAGE3) -T stage3.ld -Map=fs/dbg/kernel.map
-	$(PAD_BOUNDARY) stage3.bin 512
+stage3.elf: $(STAGE3) stage3.ld
+	ld $(LDFLAGS) $(STAGE3) -T stage3.ld -o stage3.elf
 
-fs/dbg/kernel.dis.asm: stage3.bin
+fs/dbg/kernel.dis.asm: stage3.elf
 	mkdir -p fs/dbg/
 	$(DISAS) > fs/dbg/kernel.dis.asm
 
 stage3/%.o: stage3/%.asm
-	nasm -f elf64 $< -o $@
+	nasm $(NASMFLAGS_KERNEL) -f elf64 $< -o $@
 
 stage3/interrupts.o: stage3/interrupts.c
-	gcc $(CFLAGS) -mgeneral-regs-only -c $< -o $@
+	gcc $(CFLAGS) -MMD -mgeneral-regs-only -c $< -o $@
 stage3/pic.o: stage3/pic.c
-	gcc $(CFLAGS) -mgeneral-regs-only -c $< -o $@
+	gcc $(CFLAGS) -MMD -mgeneral-regs-only -c $< -o $@
 stage3/init.o: stage3/init.c
-	gcc $(CFLAGS) -mgeneral-regs-only -c $< -o $@
+	gcc $(CFLAGS) -MMD -mgeneral-regs-only -c $< -o $@
 
 stage3/%.o: stage3/%.c
-	gcc $(CFLAGS) -c $< -o $@
+	gcc $(CFLAGS) -MMD -c $< -o $@
 
 -include $(STAGE3_C:%.o=%.d)
 
@@ -99,7 +107,7 @@ stage3/font.c: stage3/font_builtin.c
 stage3/font_builtin.c: fs/fonts/ter-u16n.cuddlefont
 	xxd -i $< > $@
 
-fs.tar: $(shell find fs | sed 's/ /\\ /g') fs/dbg/kernel.map fs/dbg/kernel.dis.asm
+fs.tar: $(shell find fs | sed 's/ /\\ /g') fs/dbg/kernel.dis.asm
 	cd fs && tar --format=ustar -cf ../fs.tar *
 
 .PHONY: run clean flash disas qemu bochs
@@ -123,5 +131,5 @@ clean:
 flash: cuddles.img
 	dd if=cuddles.img of=$(DEV)
 
-disas: stage3.bin
+disas: stage3.elf
 	$(DISAS) --disassembler-color=on
diff --git a/stage2/main.asm b/stage2/main.asm
index 3cfb5d2..5027546 100644
--- a/stage2/main.asm
+++ b/stage2/main.asm
@@ -44,8 +44,69 @@ long_mode:
 	mov gs, ax
 	mov ss, ax
 
-	; align stack
-	and rsp, ~(0x0f)
-	sub rsp, 8
+	mov eax, [kernel_elf]
+	cmp eax, [.elf]
+	jne .fail
 
-	; kernel begins here
+	mov r8, [kernel_elf+32] ; program header pos
+	add r8, kernel_elf
+
+	movzx rbx, word[kernel_elf+54] ; program header size
+	movzx rdx, word[kernel_elf+56] ; num of program headers
+
+.header:
+	cmp rdx, 0
+	je .start
+
+	mov edi, [r8] ; type
+	cmp edi, 0
+	je .next
+
+	cmp edi, 1
+	je .load
+
+	cmp edi, 2
+	je .fail
+
+	cmp edi, 3
+	je .fail
+
+	jmp .next
+
+.load:
+	; zero out the segment
+	mov al, 0
+	mov rdi, [r8+16]
+	mov rcx, [r8+40]
+	rep stosb
+
+	; load from file
+	mov rdi, [r8+16]
+	mov rsi, [r8+8]
+	add rsi, kernel_elf
+	mov rcx, [r8+32]
+	rep movsb
+
+.next:
+
+	add r8, rbx
+	dec rdx
+	jmp .header
+
+.start:
+	; more stack space
+	mov rsp, 0x80000
+	xor rbp, rbp
+
+	; ELF entry point
+	mov rax, [kernel_elf+24]
+	call rax
+
+.fail:
+	cli
+	hlt
+	jmp $
+
+.elf: db 0x7f, "ELF"
+
+kernel_elf:
diff --git a/stage2/paging.asm b/stage2/paging.asm
index cedc1e9..cd6ea1c 100644
--- a/stage2/paging.asm
+++ b/stage2/paging.asm
@@ -8,13 +8,14 @@ paging:
 .clr_buf:
 	mov byte[di], 0
 	inc di
-	cmp di, PAGETABLE+0x4000
+	cmp di, PAGETABLE+0x5000
 	jne .clr_buf
 
 	; init 3 page map levels
 	mov dword[PAGETABLE+0x0000], PAGETABLE+0x1003
 	mov dword[PAGETABLE+0x1000], PAGETABLE+0x2003
 	mov dword[PAGETABLE+0x2000], PAGETABLE+0x3003
+	mov dword[PAGETABLE+0x2008], PAGETABLE+0x4003
 
 	; fill up level 4 page map
 	mov eax, 3
@@ -23,7 +24,7 @@ paging:
 	mov [di], eax
 	add di, 8
 	add eax, 0x1000
-	cmp eax, 0x100000
+	cmp eax, 0x200000
 	jb .build_pt
 
 	; enable paging and long mode
diff --git a/stage3.ld b/stage3.ld
index 45a1486..e2d19d3 100644
--- a/stage3.ld
+++ b/stage3.ld
@@ -1,9 +1,4 @@
-OUTPUT(stage3.bin)
-OUTPUT_FORMAT(binary)
-
-SECTIONS
+MEMORY
 {
-	. = 0x9000;
-	.text : { *(.text) }
-	.data : { *(.bss .data .rodata) }
+	ram (rwx) : ORIGIN = 0x100000, LENGTH = 0x100000
 }
diff --git a/stage3/debug.c b/stage3/debug.c
index 0621dbd..ed28fee 100644
--- a/stage3/debug.c
+++ b/stage3/debug.c
@@ -4,7 +4,6 @@
 #include "halt.h"
 #include "debug.h"
 
-static str dbg_map = NILS;
 static str dbg_disas = NILS;
 
 static str exception[32] = {
@@ -37,56 +36,70 @@ static str exception[32] = {
 	NILS,
 };
 
-static void dump_frame(interrupt_frame *frame)
+static bool get_source(u64 code, str *func, str *linep)
 {
-	print(S("rip = "));
-	print_hex(frame->rip);
-
-	if (dbg_map.data != nil) {
-		str entry = NILS;
-		str iter = dbg_map;
-		while (iter.len > 0) {
-			str line = str_walk(&iter, S("\n"));
-			line = str_eat(line, S(" "));
-			if (!str_start(line, S("0x")))
+	if (dbg_disas.data == nil)
+		return false;
+
+	*func = (str) NILS;
+	*linep = (str) NILS;
+
+	str iter = dbg_disas;
+	while (iter.len > 0) {
+		str line = str_walk(&iter, S("\n"));
+		u64 func_addr;
+		usize adv;
+		if ((adv = str_parse_num(line, 16, &func_addr))) {
+			line = str_advance(line, adv);
+			if (line.len < 2 || line.data[0] != ' ' || line.data[1] != '<')
 				continue;
 			line = str_advance(line, 2);
-
+			usize close = str_find(line, S(">"));
+			*func = (str) { .len = close, .data = line.data };
+		} else {
 			u64 addr;
-			usize adv = str_parse_num(line, 16, &addr);
-			if (adv == 0)
+			if (!str_parse_num(str_eat(line, S(" ")), 16, &addr))
 				continue;
-			line = str_advance(line, adv);
-
-			if (addr > frame->rip)
-				break;
-
-			line = str_eat(line, S(" "));
-			if (line.len > 0)
-				entry = line;
+			*linep = line;
+			if (addr == code)
+				return true;
 		}
+	}
 
-		if (entry.len > 0) {
-			print(S(" in "));
-			print(entry);
-		}
+	return false;
+}
+
+static void trace(u64 code, u64 base)
+{
+	if (base == 0)
+		return;
+
+	str func, line;
+	if (get_source(code, &func, &line)) {
+		print(S("\t"));
+		print_hex(code);
+		print(S(" in "));
+		print(func);
+		print(S("\n"));
 	}
 
-	if (dbg_disas.data != nil) {
-		str iter = dbg_disas;
-		while (iter.len > 0) {
-			str line = str_walk(&iter, S("\n"));
-			u64 addr;
-			if (!str_parse_num(str_eat(line, S(" ")), 16, &addr))
-				continue;
-			if (addr == frame->rip) {
-				print(S("\n"));
-				print(line);
-				break;
-			}
-		}
+	u64 *stack = (u64 *) base;
+	trace(stack[1], stack[0]);
+}
+
+static void dump_frame(interrupt_frame *frame)
+{
+	str func, line;
+	if (get_source(frame->rip, &func, &line)) {
+		print(line);
+		print(S("\n"));
 	}
 
+	print(S("backtrace:\n"));
+	trace(frame->rip, frame->rbp);
+
+	print(S("rip = "));
+	print_hex(frame->rip);
 	print(S("\n"));
 
 	struct {
@@ -187,7 +200,7 @@ void debug_exception(interrupt_frame *frame)
 
 void debug_init()
 {
-	print(S("loading kernel debug info...\n"));
-	dbg_map = fs_read(S("dbg/kernel.map"));
+	print(S("loading kernel debug info... "));
 	dbg_disas = fs_read(S("dbg/kernel.dis.asm"));
+	print(S("done\n"));
 }
diff --git a/stage3/init.c b/stage3/init.c
index 2e26e19..c65f08b 100644
--- a/stage3/init.c
+++ b/stage3/init.c
@@ -1,7 +1,7 @@
 #include "def.h"
 void kmain();
 
-void init()
+void _start()
 {
 	// enable SSE. long mode demands it is present
 	u64 cr0;
@@ -14,5 +14,6 @@ void init()
 
 	u16 fpu_cw = 0x37a;
 	asm volatile("fldcw %0"::"m"(fpu_cw));
+
 	kmain();
 }
diff --git a/stage3/isr.lua b/stage3/isr.lua
index 3c88c5e..4810f01 100644
--- a/stage3/isr.lua
+++ b/stage3/isr.lua
@@ -6,6 +6,13 @@ for _, x in pairs({8, 10, 11, 12, 13, 14, 17, 21, 29, 30}) do
 	has_error_code[x] = true
 end
 
+print("section .data")
+print("idt_entries:")
+for i = 0, 255 do
+	print("dq isr_"..i)
+end
+
+print("section .text")
 for i = 0, 255 do
 	print("isr_" .. i .. ":")
 	print("cli")
@@ -18,11 +25,6 @@ for i = 0, 255 do
 	print("jmp isr_common")
 end
 
-print("idt_entries:")
-for i = 0, 255 do
-	print("dq isr_"..i)
-end
-
 print([[
 isr_common:
 	push r15
@@ -42,6 +44,7 @@ isr_common:
 	push rax
 
 	cld
+	xor rbp, rbp
 	mov rdi, rsp
 	call interrupt_handler
 
diff --git a/stage3/main.c b/stage3/main.c
index ae94abf..b796fd1 100644
--- a/stage3/main.c
+++ b/stage3/main.c
@@ -63,6 +63,12 @@ void kmain()
 	heap_init();
 
 #define MMAP for (MemRegion *mreg = (void *) 0x500; mreg->start != nil; mreg++)
+	MMAP {
+		if (mreg->start == (void *) 0x100000) {
+			mreg->start = (void *) 0x200000;
+			mreg->size -= 0x100000;
+		}
+	}
 
 	// backup memory map
 	usize n_mreg = 0;
diff --git a/stage3/paging.asm b/stage3/paging.asm
index 783649e..f58bb98 100644
--- a/stage3/paging.asm
+++ b/stage3/paging.asm
@@ -1,15 +1,24 @@
 global page_region
-section .text
+%define PAGEBUFSIZE 0x10 * 0x1000
+
+section .bss
+
+ALIGN(4096)
+pagebuf_data: resb PAGEBUFSIZE
+
+section .data
 
 pagebuf_init:
-	.start: dq 0x5000
-	.size: dq 0x2000
+	.start: dq pagebuf_data
+	.size: dq PAGEBUFSIZE
 	.used: dq 0
 
 pagebuf: dq pagebuf_init
 
 next_page: dq 0
 
+section .text
+
 ; allocate new page table buffer
 alloc:
 	; rsi = buffer (result)
diff --git a/stage3/watchdog.lua b/stage3/watchdog.lua
index dac4d57..8d3a206 100644
--- a/stage3/watchdog.lua
+++ b/stage3/watchdog.lua
@@ -12,9 +12,13 @@ local regs = {
 print("global watchdog")
 print("extern rand, watchdog_err")
 
+print("section .bss")
+
 print("regs_backup: resq 16")
 print("regs_rand: resq 16")
 
+print("section .text")
+
 print("watchdog:")
 
 local function iter_regs(f)