Use generic spin () instead of amd64_spin ()

kernel/amd64/apic.c

@@ -7,6 +7,7 @@
 #include <sys/debug.h>
 #include <sys/mm.h>
 #include <sys/time.h>
+#include <sys/spin.h>
 #include <uacpi/acpi.h>
 #include <uacpi/status.h>
 #include <uacpi/tables.h>
@@ -45,10 +46,6 @@ static size_t intr_src_override_entries = 0;
 /// Local APIC MMIO base address. It comes from MSR_APIC_BASE
 static uintptr_t lapic_mmio_base = 0;
 
-/** @cond DOXYGEN_IGNORE */
-extern void amd64_spin (void);
-/** @endcond */
-
 /// Read IOAPIC
 static uint32_t amd64_ioapic_read (uintptr_t vaddr, uint32_t reg) {
   *(volatile uint32_t*)vaddr = reg;
@@ -177,7 +174,7 @@ void amd64_ioapic_init (void) {
   uacpi_status status = uacpi_table_find_by_signature (ACPI_MADT_SIGNATURE, &apic_table);
   if (status != UACPI_STATUS_OK) {
     DEBUG ("Could not find MADT table!\n");
-    amd64_spin ();
+    spin ();
   }
 
   struct acpi_madt* apic = (struct acpi_madt*)apic_table.virt_addr;

kernel/amd64/hpet.c

@@ -4,6 +4,7 @@
 #include <sync/spin_lock.h>
 #include <sys/debug.h>
 #include <sys/mm.h>
+#include <sys/spin.h>
 #include <uacpi/acpi.h>
 #include <uacpi/status.h>
 #include <uacpi/tables.h>
@@ -32,10 +33,6 @@ static uint64_t hpet_clock_nano;
 /// Lock, which protects concurrent access. See \ref amd64/smp.c
 static spin_lock_t hpet_lock = SPIN_LOCK_INIT;
 
-/** @cond DOXYGEN_IGNORE */
-extern void amd64_spin (void);
-/** @endcond */
-
 /// Read a HPET register. Assumes caller holds \ref hpet_lock
 static uint64_t amd64_hpet_read (uint32_t reg) {
   struct limine_hhdm_response* hhdm = limine_hhdm_request.response;
@@ -93,7 +90,7 @@ void amd64_hpet_init (void) {
   uacpi_status status = uacpi_table_find_by_signature (ACPI_HPET_SIGNATURE, &hpet_table);
   if (status != UACPI_STATUS_OK) {
     DEBUG ("Could not find HPET table!\n");
-    amd64_spin ();
+    spin ();
   }
 
   struct acpi_hpet* hpet = (struct acpi_hpet*)hpet_table.virt_addr;

kernel/amd64/intr.c

@@ -9,6 +9,7 @@
 #include <sys/debug.h>
 #include <sys/irq.h>
 #include <sys/smp.h>
+#include <sys/spin.h>
 
 /* 8259 PIC defs. */
 #define PIC1      0x20
@@ -58,10 +59,6 @@ ALIGNED (16) static volatile struct idt_entry idt_entries[IDT_ENTRIES_MAX];
 /** @endcond */
 static volatile struct idt idt;
 
-/** @cond DOXYGEN_IGNORE */
-extern void amd64_spin (void);
-/** @endcond */
-
 /// Remaps and disables old 8259 PIC, since we'll be using APIC.
 static void amd64_init_pic (void) {
   /** @cond DOXYGEN_IGNORE */
@@ -169,7 +166,7 @@ static void amd64_intr_exception (struct saved_regs* regs) {
   if (regs->cs == (0x18 | 0x03)) {
     proc_kill (thiscpu->proc_current);
   } else {
-    amd64_spin ();
+    spin ();
   }
 }