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Separate arch-specific and arch-agnostic code

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Sam Tebbs 2019-05-12 23:31:38 +01:00 • committed by SamTebbs33
parent b1011b780f
commit 49d6f19516
4 changed files with 120 additions and 105 deletions
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104
src/kernel/kmain.zig
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@ -5,106 +5,7 @@
// Date: 2019-03-30
//
const builtin = @import("builtin");
const MultiBoot = packed struct {
magic: i32,
flags: i32,
checksum: i32,
};
const ALIGN = 1 << 0;
const MEMINFO = 1 << 1;
const MAGIC = 0x1BADB002;
const FLAGS = ALIGN | MEMINFO;
export var multiboot align(4) linksection(".rodata.boot") = MultiBoot{
.magic = MAGIC,
.flags = FLAGS,
.checksum = -(MAGIC + FLAGS),
};
const KERNEL_ADDR_OFFSET = 0xC0000000;
const KERNEL_PAGE_NUMBER = KERNEL_ADDR_OFFSET >> 22;
// The number of pages occupied by the kernel, will need to be increased as we add a heap etc.
const KERNEL_NUM_PAGES = 1;
// The initial page directory used for booting into the higher half. Should be overwritten later
export var boot_page_directory: [1024]u32 align(4096) linksection(".rodata.boot") = init: {
// Increase max number of branches done by comptime evaluator
@setEvalBranchQuota(1024);
// Temp value
var dir: [1024]u32 = undefined;
// Page for 0 -> 4 MiB. Gets unmapped later
dir[0] = 0x00000083;
var i = 0;
var idx = 1;
// Fill preceding pages with zeroes. May be unecessary but incurs no runtime cost
while (i < KERNEL_PAGE_NUMBER - 1) : ({
i += 1;
idx += 1;
}) {
dir[idx] = 0;
}
// Map the kernel's higher half pages increasing by 4 MiB every time
i = 0;
while (i < KERNEL_NUM_PAGES) : ({
i += 1;
idx += 1;
}) {
dir[idx] = 0x00000083 | (i << 22);
}
// Fill suceeding pages with zeroes. May be unecessary but incurs no runtime cost
i = 0;
while (i < 1024 - KERNEL_PAGE_NUMBER - KERNEL_NUM_PAGES) : ({
i += 1;
idx += 1;
}) {
dir[idx] = 0;
}
break :init dir;
};
export var kernel_stack: [16 * 1024]u8 align(16) linksection(".bss.stack") = undefined;
export nakedcc fn _start() align(16) linksection(".text.boot") noreturn {
// Seth the page directory to the boot directory
asm volatile (
\\.extern boot_page_directory
\\mov $boot_page_directory, %%ecx
\\mov %%ecx, %%cr3
);
// Enable 4 MiB pages
asm volatile (
\\mov %%cr4, %%ecx
\\or $0x00000010, %%ecx
\\mov %%ecx, %%cr4
);
// Enable paging
asm volatile (
\\mov %%cr0, %%ecx
\\or $0x80000000, %%ecx
\\mov %%ecx, %%cr0
);
asm volatile ("jmp start_higher_half");
while (true) {}
}
export nakedcc fn start_higher_half() noreturn {
// Invalidate the page for the first 4MiB as it's no longer needed
asm volatile ("invlpg (0)");
// Setup the stack
asm volatile (
\\.extern KERNEL_STACK_END
\\mov $KERNEL_STACK_END, %%esp
\\mov %%esp, %%ebp
);
kmain();
while (true) {}
}
const arch = @import("arch.zig");
pub fn panic(msg: []const u8, error_return_trace: ?*builtin.StackTrace) noreturn {
@setCold(true);
@ -113,7 +14,8 @@ pub fn panic(msg: []const u8, error_return_trace: ?*builtin.StackTrace) noreturn
while (true) {}
}
fn kmain() void {
pub export fn kmain() void {
arch.init();
terminal.initialize();
terminal.write("Hello, kernel World!");
}