Browse Source

Use GAS instead of YASM.

Dale Weiler 6 years ago
parent
commit
01176e0f97
15 changed files with 412 additions and 344 deletions
  1. 1 1
      .gitignore
  2. 22 17
      Makefile
  3. 57 0
      kernel/boot.S
  4. 2 2
      kernel/cpu/gdt.c
  5. 2 2
      kernel/cpu/idt.c
  6. 20 0
      kernel/gdt.S
  7. 10 0
      kernel/idt.S
  8. 68 0
      kernel/irq.S
  9. 92 0
      kernel/isr.S
  10. 24 27
      kernel/link.ld
  11. 0 271
      kernel/start.s
  12. 54 0
      kernel/task.S
  13. 10 0
      kernel/tss.S
  14. 21 0
      kernel/user.S
  15. 29 24
      util/generate_symbols.py

+ 1 - 1
.gitignore

@@ -10,7 +10,7 @@
 *.swn
 *.toc
 *.ko
-kernel/symbols.s
+kernel/symbols.S
 .compositor-check
 .config
 .gdb_history

+ 22 - 17
Makefile

@@ -11,6 +11,7 @@ CC = i686-pc-toaru-gcc
 NM = i686-pc-toaru-nm
 CXX= i686-pc-toaru-g++
 AR = i686-pc-toaru-ar
+AS = i686-pc-toaru-as
 
 # Build flags
 CFLAGS  = -O2 -std=c99
@@ -19,6 +20,8 @@ CFLAGS += -Wall -Wextra -Wno-unused-function -Wno-unused-parameter -Wno-format
 CFLAGS += -pedantic -fno-omit-frame-pointer
 CFLAGS += -D_KERNEL_
 
+ASFLAGS = --32
+
 # Kernel autoversioning with git sha
 CFLAGS += -DKERNEL_GIT_TAG=`util/make-version`
 
@@ -26,7 +29,8 @@ CFLAGS += -DKERNEL_GIT_TAG=`util/make-version`
 YASM = yasm
 
 # All of the core parts of the kernel are built directly.
-KERNEL_OBJS  = $(patsubst %.c,%.o,$(wildcard kernel/*/*.c))
+KERNEL_OBJS  = $(filter-out kernel/symbols.o,$(patsubst %.S,%.o,$(wildcard kernel/*/*.S)))
+KERNEL_OBJS += $(patsubst %.c,%.o,$(wildcard kernel/*/*.c))
 KERNEL_OBJS += $(patsubst %.c,%.o,$(wildcard kernel/*/*/*.c))
 
 # Loadable modules
@@ -39,7 +43,7 @@ HEADERS     = $(shell find kernel/include/ -type f -name '*.h')
 # Userspace build flags
 USER_CFLAGS   = -O3 -m32 -Wa,--32 -g -Iuserspace -std=c99 -U__STRICT_ANSI__
 USER_CXXFLAGS = -O3 -m32 -Wa,--32 -g -Iuserspace
-USER_BINFLAGS = 
+USER_BINFLAGS =
 
 # Userspace binaries and libraries
 USER_CFILES   = $(shell find userspace -not -wholename '*/lib/*' -name '*.c')
@@ -89,7 +93,7 @@ BOOT_MODULES += net rtl
 # which is basically -initrd "hdd/mod/%.ko,hdd/mod/%.ko..."
 # for each of the modules listed above in BOOT_MODULES
 COMMA := ,
-EMPTY := 
+EMPTY :=
 SPACE := $(EMPTY) $(EMPTY)
 BOOT_MODULES_X = -initrd "$(subst $(SPACE),$(COMMA),$(foreach mod,$(BOOT_MODULES),hdd/mod/$(mod).ko))"
 
@@ -116,10 +120,10 @@ WITH_LOGS = logtoserial=1
 .PHONY: debug debug-kvm debug-term debug-term-kvm
 
 # Prevents Make from removing intermediary files on failure
-.SECONDARY: 
+.SECONDARY:
 
 # Disable built-in rules
-.SUFFIXES: 
+.SUFFIXES:
 
 all: system tags userspace
 system: toaruos-disk.img toaruos-kernel modules
@@ -160,10 +164,11 @@ test: system
 toolchain:
 	@cd toolchain; ./toolchain-build.sh
 
+ASM_OBJS = kernel/boot.o kernel/gdt.o kernel/idt.o kernel/irq.o kernel/isr.o kernel/task.o kernel/tss.o kernel/user.o
 ################
 #    Kernel    #
 ################
-toaruos-kernel: kernel/start.o kernel/link.ld kernel/main.o kernel/symbols.o ${KERNEL_OBJS}
+toaruos-kernel: ${ASM_OBJS} kernel/link.ld kernel/main.o kernel/symbols.o ${KERNEL_OBJS}
 	@${BEG} "CC" "$<"
 	@${CC} -T kernel/link.ld ${CFLAGS} -nostdlib -o toaruos-kernel kernel/*.o ${KERNEL_OBJS} -lgcc ${ERRORS}
 	@${END} "CC" "$<"
@@ -171,18 +176,13 @@ toaruos-kernel: kernel/start.o kernel/link.ld kernel/main.o kernel/symbols.o ${K
 
 kernel/symbols.o: ${KERNEL_OBJS} util/generate_symbols.py
 	@-rm -f kernel/symbols.o
-	@${BEG} "nm" "Generating symbol list..."
+	@${BEG} "NM" "Generating symbol list..."
 	@${CC} -T kernel/link.ld ${CFLAGS} -nostdlib -o toaruos-kernel kernel/*.o ${KERNEL_OBJS} -lgcc ${ERRORS}
-	@${NM} toaruos-kernel -g | python2 util/generate_symbols.py > kernel/symbols.s
-	@${END} "nm" "Generated symbol list."
-	@${BEG} "yasm" "kernel/symbols.s"
-	@${YASM} -f elf -o $@ kernel/symbols.s ${ERRORS}
-	@${END} "yasm" "kernel/symbols.s"
-
-kernel/start.o: kernel/start.s
-	@${BEG} "yasm" "$<"
-	@${YASM} -f elf -o $@ $< ${ERRORS}
-	@${END} "yasm" "$<"
+	@${NM} toaruos-kernel -g | python2 util/generate_symbols.py > kernel/symbols.S
+	@${END} "NM" "Generated symbol list."
+	@${BEG} "AS" "kernel/symbols.S"
+	@${AS} ${ASFLAGS} kernel/symbols.S -o $@ ${ERRORS}
+	@${END} "AS" "kernel/symbols.S"
 
 kernel/sys/version.o: kernel/*/*.c kernel/*.c
 
@@ -191,6 +191,11 @@ hdd/mod/%.ko: modules/%.c ${HEADERS}
 	@${CC} -T modules/link.ld -I./kernel/include -nostdlib ${CFLAGS} -c -o $@ $< ${ERRORS}
 	@${END} "CC" "$< [module]"
 
+kernel/%.o: kernel/%.S
+	@${BEG} "AS" "$<"
+	@${AS} ${ASFLAGS} $< -o $@ ${ERRORS}
+	@${END} "AS" "$<"
+
 kernel/%.o: kernel/%.c ${HEADERS}
 	@${BEG} "CC" "$<"
 	@${CC} ${CFLAGS} -nostdlib -g -I./kernel/include -c -o $@ $< ${ERRORS}

+ 57 - 0
kernel/boot.S

@@ -0,0 +1,57 @@
+.set MB_MAGIC,              0x1BADB002
+.set MB_FLAG_PAGE_ALIGN,    1 << 0
+.set MB_FLAG_MEMORY_INFO,   1 << 1
+.set MB_FLAG_GRAPHICS,      1 << 2
+.set MB_FLAGS,              MB_FLAG_PAGE_ALIGN | MB_FLAG_MEMORY_INFO | MB_FLAG_GRAPHICS
+.set MB_CHECKSUM,           -(MB_MAGIC + MB_FLAGS)
+
+.section .multiboot
+.align 4
+
+/* Multiboot section */
+.long MB_MAGIC
+.long MB_FLAGS
+.long MB_CHECKSUM
+.long 0x00000000 /* header_addr */
+.long 0x00000000 /* load_addr */
+.long 0x00000000 /* load_end_addr */
+.long 0x00000000 /* bss_end_addr */
+.long 0x00000000 /* entry_addr */
+
+/* Request linear graphics mode */
+.long 0x00000000
+.byte 0
+.byte 0
+.byte 32
+
+/* .stack resides in .bss */
+.section .stack, "aw", @nobits
+stack_bottom:
+.skip 16384 /* 16KiB */
+stack_top:
+
+.section .text
+
+.global start
+.type start, @function
+
+.extern kmain
+.type kmain, @function
+
+start:
+    /* Setup our stack */
+    mov $stack_top, %esp
+    pushl %esp
+
+    pushl %eax /* Multiboot header magic */
+    pushl %ebx /* Multiboot header pointer */
+
+    /* Disable interrupts and call kernel proper */
+    cli
+    call kmain
+
+    /* Clear interrupts and hang if we return from kmain */
+    cli
+hang:
+    hlt
+    jmp hang

+ 2 - 2
kernel/cpu/gdt.c

@@ -43,7 +43,7 @@ struct gdt_ptr		gp;
  * (ASM) gdt_flush
  * Reloads the segment registers
  */
-extern void gdt_flush(void);
+extern void gdt_flush(unsigned int);
 
 /**
  * Set a GDT descriptor
@@ -96,7 +96,7 @@ gdt_install(void) {
 	gdt_set_gate(4, 0, 0xFFFFFFFF, 0xF2, 0xCF);
 	write_tss(5, 0x10, 0x0);
 	/* Go go go */
-	gdt_flush();
+	gdt_flush((unsigned int)&gp);
 	tss_flush();
 }
 

+ 2 - 2
kernel/cpu/idt.c

@@ -31,7 +31,7 @@ struct idt_ptr {
 struct idt_entry idt[256];
 struct idt_ptr idtp;
 
-extern void idt_load(void);
+extern void idt_load(unsigned int);
 
 /*
  * idt_set_gate
@@ -59,5 +59,5 @@ void idt_install(void) {
 	idtp.base = (uintptr_t)&idt;
 	memset(&idt, 0, sizeof(struct idt_entry) * 256);
 
-	idt_load();
+	idt_load((unsigned int)&idtp);
 }

+ 20 - 0
kernel/gdt.S

@@ -0,0 +1,20 @@
+.section .text
+.align 4
+
+.global gdt_flush
+.type gdt_flush, @function
+
+gdt_flush:
+    /* Load GDT */
+    mov 4(%esp), %eax
+    lgdt (%eax)
+
+    mov $0x10, %ax
+    mov %ax, %ds
+    mov %ax, %es
+    mov %ax, %fs
+    mov %ax, %ss
+
+    ljmp $0x08, $.flush
+.flush:
+    ret

+ 10 - 0
kernel/idt.S

@@ -0,0 +1,10 @@
+.section .text
+.align 4
+
+.global idt_load
+.type idt_load, @function
+
+idt_load:
+    mov 4(%esp), %eax
+    lidt (%eax)
+    ret

+ 68 - 0
kernel/irq.S

@@ -0,0 +1,68 @@
+.section .text
+.align 4
+
+.macro IRQ ident byte
+    .global _irq\ident
+    .type _irq\ident, @function
+    _irq\ident:
+        cli
+        push $0x00
+        push $\byte
+        jmp irq_common
+.endm
+
+/* Interrupt Requests */
+IRQ 0, 32
+IRQ 1, 33
+IRQ 2, 34
+IRQ 3, 35
+IRQ 4, 36
+IRQ 5, 37
+IRQ 6, 38
+IRQ 7, 39
+IRQ 8, 40
+IRQ 9, 41
+IRQ 10, 42
+IRQ 11, 43
+IRQ 12, 44
+IRQ 13, 45
+IRQ 14, 46
+IRQ 15, 47
+
+.extern irq_handler
+.type irq_handler, @function
+
+irq_common:
+    /* Save all registers */
+    pusha
+
+    /* Save segment registers */
+    push %ds
+    push %es
+    push %fs
+    push %gs
+    mov $0x10, %ax
+    mov %ax, %ds
+    mov %ax, %es
+    mov %ax, %fs
+    mov %ax, %gs
+
+    /* Call interrupt handler */
+    mov %esp, %eax
+    push %eax
+    mov $irq_handler, %eax
+    call *%eax
+    pop %eax
+
+    /* Restore segment registers */
+    pop %gs
+    pop %fs
+    pop %es
+    pop %ds
+
+    /* Restore all registers */
+    popa
+    /* Cleanup error code and IRQ # */
+    add $8, %esp
+    /* pop CS, EIP, EFLAGS, SS and ESP */
+    iret

+ 92 - 0
kernel/isr.S

@@ -0,0 +1,92 @@
+.section .text
+.align 4
+
+.macro ISR_NOERR index
+    .global _isr\index
+    _isr\index:
+        cli
+        push $0
+        push $\index
+        jmp isr_common
+.endm
+
+.macro ISR_ERR index
+    .global _isr\index
+    _isr\index:
+        cli
+        push $\index
+        jmp isr_common
+.endm
+
+/* Standard X86 interrupt service routines */
+ISR_NOERR 0
+ISR_NOERR 1
+ISR_NOERR 2
+ISR_NOERR 3
+ISR_NOERR 4
+ISR_NOERR 5
+ISR_NOERR 6
+ISR_NOERR 7
+ISR_ERR   8
+ISR_NOERR 9
+ISR_ERR   10
+ISR_ERR   11
+ISR_ERR   12
+ISR_ERR   13
+ISR_ERR   14
+ISR_NOERR 15
+ISR_NOERR 16
+ISR_NOERR 17
+ISR_NOERR 18
+ISR_NOERR 19
+ISR_NOERR 20
+ISR_NOERR 21
+ISR_NOERR 22
+ISR_NOERR 23
+ISR_NOERR 24
+ISR_NOERR 25
+ISR_NOERR 26
+ISR_NOERR 27
+ISR_NOERR 28
+ISR_NOERR 29
+ISR_NOERR 30
+ISR_NOERR 31
+ISR_NOERR 127
+
+.extern fault_handler
+.type fault_handler, @function
+
+isr_common:
+    /* Push all registers */
+    pusha
+
+    /* Save segment registers */
+    push %ds
+    push %es
+    push %fs
+    push %gs
+    mov $0x10, %ax
+    mov %ax, %ds
+    mov %ax, %es
+    mov %ax, %fs
+    mov %ax, %gs
+
+    /* Call fault handler */
+    mov %esp, %eax
+    push %eax
+    mov $fault_handler, %eax
+    call *%eax
+    pop %eax
+
+    /* Restore segment registers */
+    pop %gs
+    pop %fs
+    pop %es
+    pop %ds
+
+    /* Restore registers */
+    popa
+    /* Cleanup error code and ISR # */
+    add $8, %esp
+    /* pop CS, EIP, EFLAGS, SS and ESP */
+    iret

+ 24 - 27
kernel/link.ld

@@ -3,46 +3,43 @@
  */
 OUTPUT_FORMAT(elf32-i386)
 ENTRY(start)
-phys = 0x00100000;
+
 SECTIONS
 {
-	/*
-	 * Actual code
-	 */
-	.text phys : AT(phys) {
+	. = 1M;
+	phys = .;
+
+	.text BLOCK(4K) : ALIGN(4K)
+	{
 		code = .;
-		*(.multiboot*)
-		*(.text*)
-		*(.rodata*)
-		. = ALIGN(4096);
+		*(.multiboot)
+		*(.text)
+	}
+
+	.rodata BLOCK(4K) : ALIGN(4K)
+	{
+		*(.rodata)
 	}
-	/*
-	 * Kernel data
-	 */
-	.data : AT(phys + (data - code))
+
+	.data BLOCK(4K) : ALIGN(4K)
 	{
 		data = .;
-		*(.data*)
+		*(.data)
+		*(.symbols)
 		PROVIDE(kernel_symbols_start = .);
 		PROVIDE(kernel_symbols_end = .);
-		. = ALIGN(4096);
 	}
-	/*
-	 * Statically defined, uninitialized values
-	 */
-	.bss : AT(phys + (bss - code))
+
+	.bss BLOCK(4K) : ALIGN(4K)
 	{
 		bss = .;
-		*(.bss*)
-		. = ALIGN(4096);
+		*(COMMON)
+		*(.bss)
+		*(.stack)
 	}
-	/*
-	 * End of kernel.
-	 */
+
 	end = .;
-	/*
-	 * Get rid of unnecessary GCC bits.
-	 */
+
 	/DISCARD/ :
 	{
 		*(.comment)

+ 0 - 271
kernel/start.s

@@ -1,271 +0,0 @@
-; ToAruOS Start Up / Entry Point
-;
-; This file is part of ToaruOS and is released under the terms
-; of the NCSA / University of Illinois License - see LICENSE.md
-; Copyright (C) 2013-2014 Kevin Lange
-;
-BITS 32
-ALIGN 4
-
-
-SECTION .multiboot
-mboot:
-	; Multiboot headers:
-	;   Page aligned loading, please
-	MULTIBOOT_PAGE_ALIGN	equ 1<<0
-	;   We require memory information
-	MULTIBOOT_MEMORY_INFO	equ 1<<1
-	;   We would really, really like graphics...
-	MULTIBOOT_USE_GFX		equ 1<<2
-	;   We are multiboot compatible!
-	MULTIBOOT_HEADER_MAGIC	equ 0x1BADB002
-	;   Load up those flags.
-	MULTIBOOT_HEADER_FLAGS	equ MULTIBOOT_PAGE_ALIGN | MULTIBOOT_MEMORY_INFO | MULTIBOOT_USE_GFX
-	;   Checksum the result
-	MULTIBOOT_CHECKSUM		equ -(MULTIBOOT_HEADER_MAGIC + MULTIBOOT_HEADER_FLAGS)
-	; Load the headers into the binary image.
-	dd MULTIBOOT_HEADER_MAGIC
-	dd MULTIBOOT_HEADER_FLAGS
-	dd MULTIBOOT_CHECKSUM
-	dd 0x00000000 ; header_addr
-	dd 0x00000000 ; load_addr
-	dd 0x00000000 ; load_end_addr
-	dd 0x00000000 ; bss_end_addr
-	dd 0x00000000 ; entry_addr
-	; Graphics requests
-	dd 0x00000000 ; 0 = linear graphics
-	dd 0
-	dd 0
-	dd 32         ; Set me to 32 or else.
-
-
-SECTION .text
-; Some external references.
-extern code, bss, end
-
-; Main entrypoint
-global start
-start:
-	; Set up stack pointer.
-	mov esp, 0x7FFFF
-	push esp
-	; Push the incoming mulitboot headers
-	push eax ; Header magic
-	push ebx ; Header pointer
-	; Disable interrupts
-	cli
-	; Call the C entry
-	extern	kmain
-	call	kmain
-	jmp		$
-
-
-; Global Descriptor Table
-global gdt_flush
-extern gp
-gdt_flush:
-	; Load the GDT
-	lgdt [gp]
-	; Flush the values to 0x10
-	mov ax, 0x10
-	mov ds, ax
-	mov es, ax
-	mov fs, ax
-	mov gs, ax
-	mov ss, ax
-	jmp 0x08:flush2
-flush2:
-	ret
-
-; Interrupt Descriptor Table
-global idt_load
-extern idtp
-idt_load:
-	lidt [idtp]
-	ret
-
-; Return to Userspace (from thread creation)
-global return_to_userspace
-return_to_userspace:
-	pop gs
-	pop fs
-	pop es
-	pop ds
-	popa
-	add esp, 8
-	iret
-
-; Interrupt Service Routines
-%macro ISR_NOERR 1
-	global _isr%1
-	_isr%1:
-		cli
-		push byte 0
-		push byte %1
-		jmp isr_common_stub
-%endmacro
-
-%macro ISR_ERR 1
-	global _isr%1
-	_isr%1:
-		cli
-		push byte %1
-		jmp isr_common_stub
-%endmacro
-
-%macro IRQ_ENTRY 2
-	global _irq%1
-	_irq%1:
-		cli
-		push byte 0
-		push byte %2
-		jmp irq_common_stub
-%endmacro
-
-; Standard X86 interrupt service routines
-ISR_NOERR 0
-ISR_NOERR 1
-ISR_NOERR 2
-ISR_NOERR 3
-ISR_NOERR 4
-ISR_NOERR 5
-ISR_NOERR 6
-ISR_NOERR 7
-ISR_ERR   8
-ISR_NOERR 9
-ISR_ERR   10
-ISR_ERR   11
-ISR_ERR   12
-ISR_ERR   13
-ISR_ERR   14
-ISR_NOERR 15
-ISR_NOERR 16
-ISR_NOERR 17
-ISR_NOERR 18
-ISR_NOERR 19
-ISR_NOERR 20
-ISR_NOERR 21
-ISR_NOERR 22
-ISR_NOERR 23
-ISR_NOERR 24
-ISR_NOERR 25
-ISR_NOERR 26
-ISR_NOERR 27
-ISR_NOERR 28
-ISR_NOERR 29
-ISR_NOERR 30
-ISR_NOERR 31
-ISR_NOERR 127
-
-
-; Interrupt Requests
-IRQ_ENTRY 0, 32
-IRQ_ENTRY 1, 33
-IRQ_ENTRY 2, 34
-IRQ_ENTRY 3, 35
-IRQ_ENTRY 4, 36
-IRQ_ENTRY 5, 37
-IRQ_ENTRY 6, 38
-IRQ_ENTRY 7, 39
-IRQ_ENTRY 8, 40
-IRQ_ENTRY 9, 41
-IRQ_ENTRY 10, 42
-IRQ_ENTRY 11, 43
-IRQ_ENTRY 12, 44
-IRQ_ENTRY 13, 45
-IRQ_ENTRY 14, 46
-IRQ_ENTRY 15, 47
-
-; Interrupt handlers
-extern fault_handler
-isr_common_stub:
-	pusha
-	push ds
-	push es
-	push fs
-	push gs
-	mov ax, 0x10
-	mov ds, ax
-	mov es, ax
-	mov fs, ax
-	mov gs, ax
-	mov eax, esp
-	push eax
-	; Call the C kernel fault handler
-	mov eax, fault_handler
-	call eax
-	pop eax
-	pop gs
-	pop fs
-	pop es
-	pop ds
-	popa
-	add esp, 8
-	iret
-
-extern irq_handler
-irq_common_stub:
-	pusha
-	push ds
-	push es
-	push fs
-	push gs
-	mov ax, 0x10
-	mov ds, ax
-	mov es, ax
-	mov fs, ax
-	mov gs, ax
-	mov eax, esp
-	push eax
-	; Call the C kernel hardware interrupt handler
-	mov eax, irq_handler
-	call eax
-	pop eax
-	pop gs
-	pop fs
-	pop es
-	pop ds
-	popa
-	add esp, 8
-	iret
-
-global read_eip
-read_eip: ; Clever girl
-	pop eax
-	jmp eax
-
-global copy_page_physical
-copy_page_physical:
-    push ebx
-    pushf
-    cli
-    mov ebx, [esp+12]
-    mov ecx, [esp+16]
-    mov edx, cr0
-    and edx, 0x7FFFFFFF
-    mov cr0, edx
-    mov edx, 0x400
-.page_loop:
-    mov eax, [ebx]
-    mov [ecx], eax
-    add ebx, 4
-    add ecx, 4
-    dec edx
-    jnz .page_loop
-    mov edx, cr0
-    or  edx, 0x80000000
-    mov cr0, edx
-    popf
-    pop ebx
-    ret
-
-global tss_flush
-tss_flush:
-	mov ax, 0x2B
-	ltr ax
-	ret
-
-; BSS Section
-SECTION .bss
-	resb 8192 ; 8KB of memory reserved
-

+ 54 - 0
kernel/task.S

@@ -0,0 +1,54 @@
+.section .text
+.align 4
+
+.global copy_page_physical
+.type copy_page_physical, @function
+
+.set dp, 0x7FFFFFFF
+.set ep, 0x80000000
+
+copy_page_physical:
+    /* Preserve contents of EBX */
+    push %ebx
+
+    /* Preserve contents of EFLAGS */
+    pushf
+    cli
+
+    /* Load source and destination addresses */
+    mov 12(%esp), %ebx
+    mov 16(%esp), %ecx
+
+    /* Get control register and disable paging*/
+    mov %cr0, %edx
+    and $dp, %edx
+    mov %edx, %cr0
+
+    /* Copy 4096 bytes */
+    mov $0x400, %edx
+.page_loop:
+    /* Get word at source address */
+    mov (%ebx), %eax
+
+    /* Store it at destination address */
+    mov %eax, (%ecx)
+
+    /* Increment source and destination addresses to next word */
+    add $4, %ebx
+    add $4, %ecx
+
+    /* One less word to copy */
+    dec %edx
+    jnz .page_loop
+
+    /* Get control register again and enable paging */
+    mov %cr0, %edx
+    or  $ep, %edx
+    mov %edx, %cr0
+
+    /* Restore EFLAGS */
+    popf
+
+    /* Restore EBX */
+    pop %ebx
+    ret

+ 10 - 0
kernel/tss.S

@@ -0,0 +1,10 @@
+.section .text
+.align 4
+
+.global tss_flush
+.type tss_flush, @function
+
+tss_flush:
+    mov $0x2B, %ax
+    ltr %ax
+    ret

+ 21 - 0
kernel/user.S

@@ -0,0 +1,21 @@
+/* Return to Userspace (from thread creation) */
+
+.global return_to_userspace
+.type return_to_userspace, @function
+
+return_to_userspace:
+    pop %gs
+    pop %fs
+    pop %es
+    pop %ds
+    popa
+    add $8, %esp
+    iret
+
+/* Read EIP */
+.global read_eip
+.type read_eip, @function
+
+read_eip:
+    mov (%esp), %eax
+    ret

+ 29 - 24
util/generate_symbols.py

@@ -4,32 +4,37 @@
 	Generate a symbol table from nm output.
 """
 
-import fileinput
-
-def formatLine(line):
-    _, _, name = line.strip().split(" ")
-    if name == "abs":
-        # abs is a keyword, so we'll just pretend we don't have that
-        return
-    if name == "kernel_symbols_start" or name == "kernel_symbols_end":
-        # we also don't want to include ourselves...
-        return
-    zeroes = ", 0" # * (1 + 4 - ((len(name) + 1) % 4))
-    print """
-    extern %s
-    dd %s
-    db '%s'%s""" % (name, name, name, zeroes)
-
-
-print "SECTION .symbols"
-
-print "global kernel_symbols_start"
+import sys
+
+# Write extern + type
+def extern(name):
+    print ".extern %s" % (name)
+    print ".type %s, @function" % (name)
+    print ""
+
+# Write an entry
+def entry(name):
+    print ".long %s" % (name)
+    print ".asciz \"%s\"" % (name)
+    print ""
+
+ignore = [ "abs", "kernel_symbols_start", "kernel_symbols_end" ]
+lines = [ x.strip().split(" ")[2] for x in sys.stdin.readlines() if x not in ignore ]
+
+# Generate the assembly
+print ".section .symbols"
+print ""
+for name in lines:
+    extern(name)
+
+print ".global kernel_symbols_start"
 print "kernel_symbols_start:"
-for line in fileinput.input():
-    formatLine(line)
+print ""
+for name in lines:
+    entry(name)
 
-print "global kernel_symbols_end"
-print "kernel_symbols_end: ;"
+print ".global kernel_symbols_end"
+print "kernel_symbols_end:"