add injection targets

targets/startup.s

@@ -0,0 +1,110 @@
+## Bare bone boot.s from wiki.osdev.org
+
+# multiboot header
+.section .rodata.multiboot
+.align 4
+
+# magic number
+.long 0x1BADB002
+
+# flags: align, meminfo
+.long 0x3
+
+# checksum: -(magic+flags)
+.long -(0x1BADB002 + 0x3)
+
+# the initial kernel stack
+.section .kernel_stack
+.global os_stack
+.size os_stack, 4096
+
+# NOTE: New Start
+
+# .section .gdt
+# gdt_start:
+#     .quad 0x0000000000000000 # null descriptor
+#     .quad 0x00cf9a000000ffff # code segment descriptor: base=0, limit=4GB, 32-bit code
+#     .quad 0x00cf92000000ffff # data segment descriptor: base=0, limit=4GB, 32-bit data
+# gdt_end:
+#
+# gdt_descriptor:
+#     .word gdt_end - gdt_start - 1 # limit
+#     .long gdt_start # base
+#
+# .section .idt
+# idt_table:
+#     .space 256*8 # 256 entries x 8 bytes each
+# idt_descriptor:
+#     .word 256*8-1 # limit
+#     .long idt_table # base
+
+# NOTE: New End
+
+#.Lstack_bottom:
+os_stack:
+    .byte 0
+    .skip 65565 # 64 KiB
+    # .skip 16384 # 16 KiB
+    # .skip 4094 # 4 KiB
+    .byte 0
+    .Lstack_top:
+
+
+# The linker script specifies _start as the entry point to the kernel and the
+# bootloader will jump to this position once the kernel has been loaded. It
+# doesn't make sense to return from this function as the bootloader is gone.
+.section .text.startup
+.global _start
+.type _start, @function
+_start:
+# NOTE: Old Start
+
+	# Welcome to kernel mode!
+	# To set up a stack, we simply set the esp register to point to the top of
+	# our stack (as it grows downwards).
+	movl $.Lstack_top, %esp
+	# We are now ready to actually execute C code. (see ./startup.cc)
+	call os_main
+
+	# In case the function returns, we'll want to put the computer into an
+	# infinite loop. To do that, we use the clear interrupt ('cli') instruction
+	# to disable interrupts, the halt instruction ('hlt') to stop the CPU until
+	# the next interrupt arrives, and jumping to the halt instruction if it ever
+	# continues execution, just to be safe. We will create a local label rather
+	# than real symbol and jump to there endlessly.
+	cli
+	hlt
+.Lhang:
+	jmp .Lhang
+
+# NOTE: Old End
+
+# NOTE: New Start
+
+#     cli
+#
+#     lgdt gdt_descriptor # GDT
+#     lidt idt_descriptor # IDT Stub
+#
+#     # set up segment registers (flat 32-bit)
+#     movw $0x10, %ax
+#     movw %ax, %ds
+#     movw %ax, %es
+#     movw %ax, %fs
+#     movw %ax, %gs
+#     movw %ax, %ss
+#     movl $.Lstack_top, %esp # set stack
+#
+#     # call main C function
+#     call os_main
+#
+#     cli
+#     hlt
+# .Lhang:
+#     jmp .Lhang
+
+# NOTE: New End
+
+# Set the size of the _start symbol to the current location '.' minus its start.
+# This is useful when debugging or when you implement call tracing.
+.size _start, . - _start