Merge branch 'feature-paging' into develop
Completed paging feature.
This commit is contained in:
Hunter White
commit
60c857324f
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@ -2,6 +2,7 @@ bin/
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dep/
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build/
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tmp/
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.vscode/
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# ---> C++
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# Compiled Object files
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19
Makefile
19
Makefile
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@ -30,7 +30,7 @@ CPPSOURCES := $(shell find $(SRCDIR) -type f -name "*.$(CPPSRCEXT)")
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OBJECTS := $(patsubst $(SRCDIR)/%,$(BUILDDIR)/%,$(CSOURCES:.$(CSRCEXT)=.o)) $(patsubst $(SRCDIR)/%,$(BUILDDIR)/%,$(CPPSOURCES:.$(CPPSRCEXT)=.o))
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#Get assembly source files and create objects from them
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ASSOURCES := $(shell find $(SRCDIR) -type f -name "*.$(ASSRCEXT)")
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ASSOURCES := $(shell find $(SRCDIR) -name global-$(ARCH) -prune -false -o -type f -name "*.$(ASSRCEXT)" -print)
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ASOBJECTS := $(patsubst $(SRCDIR)/%,$(BUILDDIR)/%,$(ASSOURCES:.$(ASSRCEXT)=.o))
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#Find dependencies from C and C++ source files
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@ -48,7 +48,7 @@ FLAGS := -O2 -Wall -Wextra -g -D__is_kernel -ffreestanding -fstack-protector
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#Specific flags
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CFLAGS := $(FLAGS) -std=gnu99
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CXXFLAGS := $(FLAGS) -std=c++17
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ASFLAGS :=
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ASFLAGS := -g --gstabs+ --gdwarf-5
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#Make sure certain directories are made
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$(shell mkdir -p $(BUILDDIR) $(DEPDIR) bin/)
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@ -61,27 +61,28 @@ $(shell mkdir -p $(patsubst $(SRCDIR)/%, $(DEPDIR)/%, $(TREE)))
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GLOBALARCHDIR := $(BUILDDIR)/arch/global-$(ARCH)
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#Define/create the global constructor objects
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CRTBEGINOBJ := $($(C) $(CFLAGS) -print-file-name=crtbegin.o)
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CRTENDOBJ := $($(C) $(CFLAGS) -print-file-name=crtend.o)
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CRTBEGINOBJ := $(shell $(C) $(CFLAGS) -print-file-name=crtbegin.o)
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CRTENDOBJ := $(shell $(C) $(CFLAGS) -print-file-name=crtend.o)
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CRTBEGIN := $(GLOBALARCHDIR)/crti.o $(CRTBEGINOBJ)
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CRTEND := $(CRTENDOBJ) $(GLOBALARCHDIR)/crtn.o
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MAKEOBJS := $(GLOBALARCHDIR)/crti.o $(GLOBALARCHDIR)/crtn.o $(SRCDIR)/linker.ld $(OBJECTS) $(ASOBJECTS)
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#Order the objects to prevent weird gcc bugs with global constructors
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MAINOBJS := $(CRTBEGIN) $(OBJECTS) $(ASOBJECTS) $(CRTEND)
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#Compile Target
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bin/ZoarialBareOS.iso: bin/ZoarialBareOS.bin bin/grub.cfg
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grub2-file --is-x86-multiboot bin/ZoarialBareOS.bin
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mkdir -p $(BUILDDIR)/isodir/boot/grub
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cp bin/ZoarialBareOS.bin $(BUILDDIR)/isodir/boot/
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cp $(SRCDIR)/grub.cfg $(BUILDDIR)/isodir/boot/grub/grub.cfg
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grub2-mkrescue -o $@ $(BUILDDIR)/isodir
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bin/ZoarialBareOS.bin: $(MAINOBJS)
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bin/ZoarialBareOS.bin: $(MAKEOBJS)
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@echo " Linking... $(MAINOBJS)"
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$(C) -T $(SRCDIR)/linker.ld $^ -o $@ -ffreestanding -O2 -nostdlib -lgcc
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grub2-file --is-x86-multiboot $@
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mkdir -p $(BUILDDIR)/isodir/boot/grub
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$(C) -T $(SRCDIR)/linker.ld $(MAINOBJS) -o $@ -ffreestanding -O2 -nostdlib -lgcc
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bin/grub.cfg: $(SRCDIR)/grub.cfg
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cp $(SRCDIR)/grub.cfg bin/grub.cfg
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@ -12,11 +12,17 @@ search for this signature in the first 8 KiB of the kernel file, aligned at a
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32-bit boundary. The signature is in its own section so the header can be
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forced to be within the first 8 KiB of the kernel file.
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*/
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.section .multiboot
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.section .multiboot.data, "aw", @progbits
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.align 4
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.long MAGIC
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.long FLAGS
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.long CHECKSUM
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.long 0
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.long 0
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.long 0
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.long 0
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.long 0
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/*
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The multiboot standard does not define the value of the stack pointer register
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@ -30,18 +36,29 @@ System V ABI standard and de-facto extensions. The compiler will assume the
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stack is properly aligned and failure to align the stack will result in
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undefined behavior.
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*/
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.section .bss
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.section .bootstrap_stack, "aw", @nobits
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.align 16
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stack_bottom:
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.skip 16384 # 16 KiB
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stack_top:
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# Preallocate pages used for paging. Don't hard-code addresses and assume they
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# are available, as the bootloader might have loaded its multiboot structures or
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# modules there. This lets the bootloader know it must avoid the addresses.
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.section .bss, "aw", @nobits
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.align 4096
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boot_page_directory:
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.skip 4096
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boot_page_table1:
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.skip 4096
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# Further page tables may be required if the kernel grows beyond 3 MiB.
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/*
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The linker script specifies _start as the entry point to the kernel and the
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bootloader will jump to this position once the kernel has been loaded. It
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doesn't make sense to return from this function as the bootloader is gone.
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*/
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.section .text
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.section .paging.setup.text, "ax", @progbits
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.global _start
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.type _start, @function
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_start:
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@ -57,7 +74,80 @@ _start:
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itself. It has absolute and complete power over the
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machine.
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*/
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# Physical address of boot_page_table1.
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# TODO: I recall seeing some assembly that used a macro to do the
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# conversions to and from physical. Maybe this should be done in this
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# code as well?
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movl $(boot_page_table1 - 0xC0000000), %edi
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# First address to map is address 0.
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# TODO: Start at the first kernel page instead. Alternatively map the first
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# 1 MiB as it can be generally useful, and there's no need to
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# specially map the VGA buffer.
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movl $0, %esi
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# Map 1023 pages. The 1024th will be the VGA text buffer.
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movl $1023, %ecx
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1:
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# Only map the kernel.
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cmpl $(_kernel_start), %esi
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jl 2f
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cmpl $(_kernel_end - 0xC0000000), %esi
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jge 3f
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# Map physical address as "present, writable". Note that this maps
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# .text and .rodata as writable. Mind security and map them as non-writable.
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movl %esi, %edx
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orl $0x003, %edx
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movl %edx, (%edi)
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2:
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# Size of page is 4096 bytes.
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addl $4096, %esi
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# Size of entries in boot_page_table1 is 4 bytes.
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addl $4, %edi
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# Loop to the next entry if we haven't finished.
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loop 1b
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3:
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# Map VGA video memory to 0xC03FF000 as "present, writable".
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movl $(0x000B8000 | 0x003), boot_page_table1 - 0xC0000000 + 1023 * 4
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# The page table is used at both page directory entry 0 (virtually from 0x0
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# to 0x3FFFFF) (thus identity mapping the kernel) and page directory entry
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# 768 (virtually from 0xC0000000 to 0xC03FFFFF) (thus mapping it in the
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# higher half). The kernel is identity mapped because enabling paging does
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# not change the next instruction, which continues to be physical. The CPU
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# would instead page fault if there was no identity mapping.
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# Map the page table to both virtual addresses 0x00000000 and 0xC0000000.
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movl $(boot_page_table1 - 0xC0000000 + 0x003), boot_page_directory - 0xC0000000 + 0
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movl $(boot_page_table1 - 0xC0000000 + 0x003), boot_page_directory - 0xC0000000 + 768 * 4
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# Set cr3 to the address of the boot_page_directory.
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movl $(boot_page_directory - 0xC0000000), %ecx
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movl %ecx, %cr3
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# Enable paging and the write-protect bit.
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movl %cr0, %ecx
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orl $0x80010000, %ecx
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movl %ecx, %cr0
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# Jump to higher half with an absolute jump.
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lea 4f, %ecx
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jmp *%ecx
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.section .text
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4:
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# At this point, paging is fully set up and enabled.
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# Unmap the identity mapping as it is now unnecessary.
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movl $0, boot_page_directory + 0
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# Reload crc3 to force a TLB flush so the changes to take effect.
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movl %cr3, %ecx
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movl %ecx, %cr3
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/*
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To set up a stack, we set the esp register to point to the top of the
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stack (as it grows downwards on x86 systems). This is necessarily done
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@ -107,4 +197,4 @@ _start:
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Set the size of the _start symbol to the current location '.' minus its start.
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This is useful when debugging or when you implement call tracing.
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*/
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.size _start, . - _start
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# .size _start, . - _start
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@ -37,7 +37,7 @@ void terminal_initialize(void)
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terminal_row = 0;
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terminal_column = 0;
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terminal_color = vga_entry_color(VGA_COLOR_LIGHT_GREY, VGA_COLOR_BLACK);
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terminal_buffer = (uint16_t*) 0xB8000;
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terminal_buffer = (uint16_t*) 0xC03FF000;
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for (size_t y = 0; y < VGA_HEIGHT; y++) {
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for (size_t x = 0; x < VGA_WIDTH; x++) {
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const size_t index = y * VGA_WIDTH + x;
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@ -13,31 +13,46 @@ SECTIONS
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/* First put the multiboot header, as it is required to be put very early
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early in the image or the bootloader won't recognize the file format.
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Next we'll put the .text section. */
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.text BLOCK(4K) : ALIGN(4K)
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_kernel_start = .;
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.multiboot.data ALIGN(4K) :
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{
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*(.multiboot.data)
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}
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.paging.setup.text :
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{
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*(.paging.setup.text)
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}
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. += 0xC0000000;
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.text ALIGN(4K) : AT (ADDR (.text) - 0xC0000000)
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{
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*(.multiboot)
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*(.text)
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}
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/* Read-only data. */
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.rodata BLOCK(4K) : ALIGN(4K)
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.rodata ALIGN(4K) : AT (ADDR (.rodata) - 0xC0000000)
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{
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*(.rodata)
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}
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/* Read-write data (initialized) */
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.data BLOCK(4K) : ALIGN(4K)
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.data ALIGN(4K) : AT (ADDR (.data) - 0xC0000000)
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{
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*(.data)
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}
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/* Read-write data (uninitialized) and stack */
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.bss BLOCK(4K) : ALIGN(4K)
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.bss ALIGN(4K) : AT (ADDR (.bss) - 0xC0000000)
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{
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*(COMMON)
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*(.bss)
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*(.bootstrap_stack)
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}
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/* The compiler may produce other sections, by default it will put them in
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a segment with the same name. Simply add stuff here as needed. */
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_kernel_end = .;
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}
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