Hooks to get the other CPUs into long mode

arch/x86_64/src/acpi/mod.rs

@@ -1,6 +1,8 @@
 //! # ACPI
 //! Code to parse the ACPI tables
 
+use core::intrinsics::{atomic_load, atomic_store};
+
 use memory::{Frame, FrameAllocator};
 use paging::{entry, ActivePageTable, Page, PhysicalAddress, VirtualAddress};
 
@@ -16,6 +18,9 @@ pub mod rsdt;
 pub mod sdt;
 pub mod xsdt;
 
+const TRAMPOLINE: usize = 0x7E00;
+const AP_STARTUP: usize = 0x8000;
+
 pub fn init_sdt(sdt: &'static Sdt) {
     print!("  ");
     for &c in sdt.signature.iter() {
@@ -37,16 +42,33 @@ pub fn init_sdt(sdt: &'static Sdt) {
                     println!("        This is my local APIC");
                 } else {
                     if asp_local_apic.flags & 1 == 1 {
+                        let ap_ready = TRAMPOLINE as *mut u64;
+                        let ap_stack = unsafe { ap_ready.offset(1) };
+
+                        // Set the ap_ready to 0, volatile
+                        unsafe { atomic_store(ap_ready, 0) };
+
+                        // Send INIT IPI
                         {
                             let icr = 0x00004500 | (asp_local_apic.id as u64) << 32;
                             println!("        Sending IPI to {}: {:>016X} {:?}", asp_local_apic.id, icr, LocalApicIcr::from_bits(icr));
                             local_apic.set_icr(icr);
                         }
+
+                        // Send START IPI
                         {
-                            let icr = 0x00004600 | (asp_local_apic.id as u64) << 32;
+                            let ap_segment = (AP_STARTUP >> 12) & 0xFF;
+                            let icr = 0x00004600 | ((asp_local_apic.id as u64) << 32) | ap_segment as u64; //Start at 0x0800:0000 => 0x8000. Hopefully the bootloader code is still there
                             println!("        Sending SIPI to {}: {:>016X} {:?}", asp_local_apic.id, icr, LocalApicIcr::from_bits(icr));
                             local_apic.set_icr(icr);
                         }
+
+                        // Wait for trampoline ready
+                        println!("        Waiting for AP {}", asp_local_apic.id);
+                        while unsafe { atomic_load(ap_ready) } == 0 {
+                            unsafe { asm!("pause" : : : : "intel", "volatile") };
+                        }
+                        println!("        AP {} is ready!", asp_local_apic.id);
                     } else {
                         println!("        CPU Disabled");
                     }
@@ -63,15 +85,6 @@ pub fn init_sdt(sdt: &'static Sdt) {
 pub unsafe fn init<A>(allocator: &mut A, active_table: &mut ActivePageTable) -> Option<Acpi>
     where A: FrameAllocator
 {
-    // Stupidity of enormous proportion. Write the halt opcode to the 0'th physical address
-    // so that START IPI's can halt the processor
-    {
-        if active_table.translate_page(Page::containing_address(VirtualAddress::new(0))).is_none() {
-            active_table.identity_map(Frame::containing_address(PhysicalAddress::new(0)), entry::PRESENT | entry::WRITABLE, allocator);
-        }
-        unsafe { *(0 as *mut u8) = 0xF4 };
-    }
-
     let start_addr = 0xE0000;
     let end_addr = 0xFFFFF;
 
@@ -86,6 +99,13 @@ pub unsafe fn init<A>(allocator: &mut A, active_table: &mut ActivePageTable) ->
         }
     }
 
+    // Map trampoline
+    {
+        if active_table.translate_page(Page::containing_address(VirtualAddress::new(TRAMPOLINE))).is_none() {
+            active_table.identity_map(Frame::containing_address(PhysicalAddress::new(TRAMPOLINE)), entry::PRESENT | entry::WRITABLE, allocator);
+        }
+    }
+
     // Search for RSDP
     if let Some(rsdp) = RSDP::search(start_addr, end_addr) {
         println!("{:?}", rsdp);

bootloader/x86/startup-x86_64.asm

@@ -1,3 +1,45 @@
+trampoline:
+    .ready: dq 0
+    .stack: dq 0
+
+    times 512 - ($ - trampoline) db 0
+
+startup_ap:
+    cli
+
+    xor ax, ax
+    mov ds, ax
+    mov es, ax
+    mov ss, ax
+
+    ; initialize stack
+    mov sp, 0x7C00
+
+    ;cr3 holds pointer to PML4
+    mov edi, 0x70000
+    mov cr3, edi
+
+    ;enable Page Address Extension and Page Size Extension
+    mov eax, cr4
+    or eax, 1 << 5 | 1 << 4
+    mov cr4, eax
+
+    ; load protected mode GDT
+    lgdt [gdtr]
+
+    mov ecx, 0xC0000080               ; Read from the EFER MSR.
+    rdmsr
+    or eax, 1 << 11 | 1 << 8          ; Set the Long-Mode-Enable and NXE bit.
+    wrmsr
+
+    ;enabling paging and protection simultaneously
+    mov ebx, cr0
+    or ebx, 1 << 31 | 1 << 16 | 1                ;Bit 31: Paging, Bit 16: write protect kernel, Bit 0: Protected Mode
+    mov cr0, ebx
+
+    ; far jump to enable Long Mode and load CS with 64 bit segment
+    jmp gdt.kernel_code:long_mode_ap
+
 %include "startup-common.asm"
 
 startup_arch:
@@ -74,9 +116,21 @@ long_mode:
     ;rust init
     xor rax, rax
     mov eax, [kernel_base + 0x18]
-    mov rbx, gdtr
     jmp rax
 
+long_mode_ap:
+    mov rax, gdt.kernel_data
+    mov ds, rax
+    mov es, rax
+    mov fs, rax
+    mov gs, rax
+    mov ss, rax
+
+    mov qword [trampoline.ready], 1
+.lp:
+    hlt
+    jmp .lp
+
 gdtr:
     dw gdt.end + 1  ; size
     dq gdt          ; offset