Implement Hikari Custom Boot Loader

1 files changed, 146 insertions, 0 deletions

diff --git a/hikari/asm/asm.zig b/hikari/asm/asm.zig
new file mode 100644
index 0000000..962fe60
--- /dev/null
+++ b/hikari/asm/asm.zig
@@ -0,0 +1,146 @@
+//! Hikari Assembly Operations
+
+pub inline fn read_cr3() u64 {
+    return asm volatile ("mov %cr3, %[ret]"
+        : [ret] "=r" (-> u64),
+    );
+}
+
+pub inline fn write_cr3(value: u64) void {
+    asm volatile ("mov %[value], %cr3"
+        :
+        : [value] "r" (value),
+        : .{ .memory = true });
+}
+
+pub inline fn read_cr0() u64 {
+    return asm volatile ("mov %cr0, %[ret]"
+        : [ret] "=r" (-> u64),
+    );
+}
+
+pub inline fn write_cr0(value: u64) void {
+    asm volatile ("mov %[value], %cr0"
+        :
+        : [value] "r" (value),
+    );
+}
+
+pub inline fn read_cr4() u64 {
+    return asm volatile ("mov %cr4, %[ret]"
+        : [ret] "=r" (-> u64),
+    );
+}
+
+pub inline fn write_cr4(value: u64) void {
+    asm volatile ("mov %[value], %cr4"
+        :
+        : [value] "r" (value),
+    );
+}
+
+pub inline fn read_msr(msr: u32) u64 {
+    var low: u32 = undefined;
+    var high: u32 = undefined;
+    asm volatile ("rdmsr"
+        : [low] "={eax}" (low),
+          [high] "={edx}" (high),
+        : [msr] "{ecx}" (msr),
+    );
+    return (@as(u64, high) << 32) | low;
+}
+
+pub inline fn write_msr(msr: u32, value: u64) void {
+    const low: u32 = @truncate(value);
+    const high: u32 = @truncate(value >> 32);
+    asm volatile ("wrmsr"
+        :
+        : [msr] "{ecx}" (msr),
+          [low] "{eax}" (low),
+          [high] "{edx}" (high),
+    );
+}
+
+pub inline fn halt() noreturn {
+    while (true) {
+        asm volatile ("hlt");
+    }
+}
+
+pub inline fn disable_interrupts() void {
+    asm volatile ("cli");
+}
+
+pub inline fn enable_interrupts() void {
+    asm volatile ("sti");
+}
+
+pub inline fn invlpg(address: u64) void {
+    asm volatile ("invlpg (%[addr])"
+        :
+        : [addr] "r" (address),
+        : .{ .memory = true });
+}
+
+pub inline fn flush_tlb() void {
+    const cr3 = read_cr3();
+    write_cr3(cr3);
+}
+
+pub const msr_efer: u32 = 0xC0000080;
+pub const efer_sce: u64 = 1 << 0;
+pub const efer_lme: u64 = 1 << 8;
+pub const efer_lma: u64 = 1 << 10;
+pub const efer_nxe: u64 = 1 << 11;
+
+pub const cr0_pe: u64 = 1 << 0;
+pub const cr0_mp: u64 = 1 << 1;
+pub const cr0_em: u64 = 1 << 2;
+pub const cr0_ts: u64 = 1 << 3;
+pub const cr0_et: u64 = 1 << 4;
+pub const cr0_ne: u64 = 1 << 5;
+pub const cr0_wp: u64 = 1 << 16;
+pub const cr0_am: u64 = 1 << 18;
+pub const cr0_nw: u64 = 1 << 29;
+pub const cr0_cd: u64 = 1 << 30;
+pub const cr0_pg: u64 = 1 << 31;
+
+pub const cr4_vme: u64 = 1 << 0;
+pub const cr4_pvi: u64 = 1 << 1;
+pub const cr4_tsd: u64 = 1 << 2;
+pub const cr4_de: u64 = 1 << 3;
+pub const cr4_pse: u64 = 1 << 4;
+pub const cr4_pae: u64 = 1 << 5;
+pub const cr4_mce: u64 = 1 << 6;
+pub const cr4_pge: u64 = 1 << 7;
+pub const cr4_pce: u64 = 1 << 8;
+pub const cr4_osfxsr: u64 = 1 << 9;
+pub const cr4_osxmmexcpt: u64 = 1 << 10;
+pub const cr4_fsgsbase: u64 = 1 << 16;
+pub const cr4_osxsave: u64 = 1 << 18;
+pub const cr4_smep: u64 = 1 << 20;
+pub const cr4_smap: u64 = 1 << 21;
+
+pub fn jump_to_kernel(
+    entry_point: u64,
+    stack_top: u64,
+    boot_params: u64,
+    pml4_address: u64,
+) noreturn {
+    disable_interrupts();
+
+    write_cr3(pml4_address);
+
+    asm volatile (
+        \\mov %[stack], %%rsp
+        \\mov %[params], %%rdi
+        \\xor %%rbp, %%rbp
+        \\jmp *%[entry]
+        :
+        : [stack] "r" (stack_top),
+          [params] "r" (boot_params),
+          [entry] "r" (entry_point),
+        : .{ .memory = true });
+
+    unreachable;
+}