higher half

5 files changed, 77 insertions, 32 deletions

diff --git a/kernel/src/boot/boot.S b/kernel/src/boot/boot.S
index bf5251b..81584ce 100644
--- a/kernel/src/boot/boot.S
+++ b/kernel/src/boot/boot.S
@@ -1,12 +1,13 @@
+.code32
 .global _start
 .extern begin_long_mode
 
-.section .text
-.code32
+.set KERNEL_VMA, 0xc0000000
 
+.section .boot.text, "a"
 _start:
 	cli
-	mov $stack_top, %esp
+	mov $stack_top - KERNEL_VMA, %esp
 	pushl $0
 	pushl %eax
 	pushl $0
@@ -19,9 +20,9 @@ _start:
 	call setup_page_tables
 	call enable_paging
 
-	lgdt gdt_pointer
-	ljmp $0x08, $begin_long_mode
-
+	addl $KERNEL_VMA, %esp
+	mov $4f, %ecx
+	jmp *%ecx
 
 check_multiboot:
 	cmp $0x36d76289, %eax
@@ -59,27 +60,46 @@ check_long_mode:
 	ret
 
 setup_page_tables:
-	mov $pt_lvl3, %eax
+	mov $pt_lvl3 - KERNEL_VMA, %eax
 	or $0x3, %eax
-	mov %eax, pt_lvl4
+	mov %eax, pt_lvl4 - KERNEL_VMA
 
-	// 0x00000000 -  0x00200000 : 0x00000000
-	mov $pt_lvl2, %eax
+	// 0x00000000 - 0x00200000 : 0x00000000 - 0x00200000
+	mov $pt_lvl2 - KERNEL_VMA, %eax
 	or $0x3, %eax
-	mov %eax, pt_lvl3
+	mov %eax, pt_lvl3 - KERNEL_VMA
 
-	movl $0, %ecx
+	// 0xc0000000 - 0xc0200000 : 0xc0000000 - 0xc0200000
+	mov $pt_lvl2_hh - KERNEL_VMA, %eax
+	or $0x3, %eax
+	mov %eax, pt_lvl3 + 24 - KERNEL_VMA
+
+// first 2mb
+	xor %ecx, %ecx
 1:
 	movl $0x00200000, %eax
 	mul %ecx
 	or $0b10000011, %eax
-	movl $pt_lvl2, %edx
+	movl $pt_lvl2 - KERNEL_VMA, %edx
 	leal (%edx, %ecx, 8), %edx
 	movl %eax, (%edx)
 	inc %ecx
 	cmp $1, %ecx
 	jne 1b
 
+// first 2mb in higher_half
+	xor %ecx, %ecx
+2:
+	movl $0x00200000, %eax
+	mul %ecx
+	or $0b10000011, %eax
+	movl $pt_lvl2_hh - KERNEL_VMA, %edx
+	leal (%edx, %ecx, 8), %edx
+	movl %eax, (%edx)
+	inc %ecx
+	cmp $1, %ecx
+	jne 2b
+
 	ret
 
 enable_paging:
@@ -95,7 +115,7 @@ enable_paging:
 	wrmsr
 
 	// pt_lvl4
-	mov $pt_lvl4, %eax
+	mov $pt_lvl4 - KERNEL_VMA, %eax
 	mov %eax, %cr3
 
 	// enable paging (+ protected mode if not already enabled)
@@ -114,6 +134,11 @@ no_cpuid:
 no_long_mode:
 	hlt
 
+.section .text
+4:
+	lgdt gdt_pointer
+	ljmp $0x08, $begin_long_mode
+
 
 .section .bss
 .align 4096
@@ -123,14 +148,17 @@ stack_bottom:
 	.skip 4096*4
 stack_top:
 
+
 // page tables
 pt_lvl4:
 	.skip 4096
 pt_lvl3:
 	.skip 4096
-// map first 4GB
 pt_lvl2:
 	.skip 4096
+pt_lvl2_hh:
+	.skip 4096
+
 
 // Access bits
 .section .rodata
diff --git a/kernel/src/boot/multiboot2.c b/kernel/src/boot/multiboot2.c
index 2badae9..fd8a652 100644
--- a/kernel/src/boot/multiboot2.c
+++ b/kernel/src/boot/multiboot2.c
@@ -2,6 +2,10 @@
 
 #include <multiboot2.h>
 #include <graphics.h>
+#include <debug.h>
+
+
+#define KERNEL_VMA 0xc0000000
 
 fb_t fb;
 
@@ -18,7 +22,8 @@ void init_fb(mb2_tag_header* multiboot_bootinfo, uint32_t multiboot_magic)
 	static mb2_tag_fb* tag_fb;
 
 	// skip first 8 bytes (total_size + reserved)
-	mb2_tag_header* tag_header = multiboot_bootinfo + 1;
+	mb2_tag_header* tag_header = (mb2_tag_header*)((char*)multiboot_bootinfo + 8 + KERNEL_VMA);
+	bochs_breakpoint();
 
 	while (tag_header->type != MB2_TAG_END) {
 		// process tag_type
diff --git a/kernel/src/kernel.ld b/kernel/src/kernel.ld
index da5c87c..56b5647 100644
--- a/kernel/src/kernel.ld
+++ b/kernel/src/kernel.ld
@@ -1,30 +1,36 @@
 ENTRY(_start)
 
+KERNEL_PMA = 0x00100000;
+KERNEL_VMA = 0xc0000000;
+
 SECTIONS
 {
-	. = 1M;
+	. = KERNEL_PMA;
 
 	.boot BLOCK(4K) : ALIGN(4K)
 	{
 		KEEP(*(.multiboot_header))
+		*(.boot.text)
 	}
 
-	.text BLOCK(4K) : ALIGN(4K)
+	. += KERNEL_VMA;
+
+	.text ALIGN(4K) : AT (ADDR (.text) - KERNEL_VMA)
 	{
 		*(.text)
 	}
 
-	.rodata BLOCK(4K) : ALIGN(4K)
+	.rodata ALIGN(4K) : AT (ADDR (.rodata) - KERNEL_VMA)
 	{
 		*(.rodata)
 	}
 
-	.data BLOCK(4K) : ALIGN(4K)
+	.data ALIGN(4K) : AT (ADDR (.data) - KERNEL_VMA)
 	{
 		*(.data)
 	}
 
-	.bss BLOCK(4K) : ALIGN(4K)
+	.bss ALIGN(4K) : AT (ADDR (.bss) - KERNEL_VMA)
 	{
 		*(COMMON)
 		*(.bss)
@@ -32,8 +38,7 @@ SECTIONS
 
 	/DISCARD/ :
 	{
-		*(.comment.*)
+		*(.comment)
 		*(.note.*)
-		*(.eh_frame)
 	}
 }
diff --git a/kernel/src/mem/paging.c b/kernel/src/mem/paging.c
index 3f9e2f5..f0181cd 100644
--- a/kernel/src/mem/paging.c
+++ b/kernel/src/mem/paging.c
@@ -6,30 +6,31 @@ void load_pt_lvl4(uint64_t*);
 
 __attribute__((aligned(4096))) uint64_t page_table_lvl4[512];
 __attribute__((aligned(4096))) uint64_t page_table_lvl3[512];
-__attribute__((aligned(4096))) uint64_t page_table_lvl2_kernel[512];
-__attribute__((aligned(4096))) uint64_t page_table_lvl2_fb[512];
+__attribute__((aligned(4096))) uint64_t page_table_lvl2_hh[512];
 
 #define PAGE_SIZE 0x00200000
 #define FLAG_PRESENT 0x1
 #define FLAG_WRITABLE 0x2
 #define FLAG_HUGE 0x80
+#define KERNEL_VMA 0xc0000000
 
 void init_paging(void)
 {
-	page_table_lvl4[0] = (uint64_t)page_table_lvl3 + FLAG_PRESENT + FLAG_WRITABLE;
-	page_table_lvl3[0] = (uint64_t)page_table_lvl2_kernel + FLAG_PRESENT + FLAG_WRITABLE;
-	page_table_lvl3[3] = (uint64_t)page_table_lvl2_fb + FLAG_PRESENT + FLAG_WRITABLE;
+	page_table_lvl4[0] = (uint64_t)page_table_lvl3 + FLAG_PRESENT + FLAG_WRITABLE - KERNEL_VMA;
+	page_table_lvl3[3] = (uint64_t)page_table_lvl2_hh + FLAG_PRESENT + FLAG_WRITABLE - KERNEL_VMA;
 
-	// 0x00000000 - 0x00400000 : 0x00000000 - 0x00400000
+	// higher half kernel
+	// 0xc0000000 - 0xc0400000 : 0xc0000000 - 0xc0400000
 	for (uint64_t i = 0; i < 2; i++) {
-		page_table_lvl2_kernel[i] = i * PAGE_SIZE + FLAG_PRESENT + FLAG_WRITABLE + FLAG_HUGE;
+		page_table_lvl2_hh[i] = i * PAGE_SIZE + FLAG_PRESENT + FLAG_WRITABLE + FLAG_HUGE;
 	}
 
 	// TODO: remove initial mapping for fb and instead page on demand
 
+	// identity paged for fb
 	// 0xe0000000 - 0xffffffff : 0xe0000000 - 0xffffffff
-	for (uint64_t i = 0; i < 512; i++) {
-		page_table_lvl2_fb[i] = i * PAGE_SIZE + 0xc0000000 + FLAG_PRESENT + FLAG_WRITABLE + FLAG_HUGE;
+	for (uint64_t i = 2; i < 512; i++) {
+		page_table_lvl2_hh[i] = i * PAGE_SIZE + 0xc0000000 + FLAG_PRESENT + FLAG_WRITABLE + FLAG_HUGE;
 	}
 
 	load_pt_lvl4(page_table_lvl4);
diff --git a/kernel/src/mem/paging_asm.S b/kernel/src/mem/paging_asm.S
index 508930f..c7e11f3 100644
--- a/kernel/src/mem/paging_asm.S
+++ b/kernel/src/mem/paging_asm.S
@@ -1,11 +1,17 @@
 .section .text
 
+.set KERNEL_VMA, 0xc0000000
+
 .global load_pt_lvl4
 load_pt_lvl4:
 	push %rbp
 	mov %rsp, %rbp
 
+	push %r12
+	mov $KERNEL_VMA, %r12
+	sub %r12, %rdi
 	mov %rdi, %cr3
+	pop %r12
 
 	mov %rbp, %rsp
 	pop %rbp