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Diffstat (limited to 'kernel')
-rw-r--r--kernel/src/boot/boot.S58
-rw-r--r--kernel/src/boot/multiboot2.c7
-rw-r--r--kernel/src/kernel.ld19
-rw-r--r--kernel/src/mem/paging.c19
-rw-r--r--kernel/src/mem/paging_asm.S6
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
generated by cgit v1.2.3 (git 2.46.0) at 2025-12-17 10:36:14 +0000