Add _irqsave variant of spinlocks

include/sys/spin.h

@@ -1,4 +1,5 @@
 #pragma once
+#include "sys/types.h"
 
 #if defined(ARCH_AMD64)
 #include "sys/amd64/sys/spin.h"
@@ -6,3 +7,5 @@
 
 void spin_lock(spin_t *s);
 void spin_release(spin_t *s);
+void spin_lock_irqsave(spin_t *s, uintptr_t *irq);
+void spin_release_irqrestore(spin_t *s, uintptr_t *irq);

sys/amd64/sys/sched.c

@@ -17,6 +17,7 @@ static struct thread t_idle[AMD64_MAX_SMP] = {0};
 void idle_func(uintptr_t id) {
     while (1) {
         kdebug("%d\n", id);
+        asm volatile ("sti; hlt");
     }
 }
 

sys/amd64/sys/spin_s.S

@@ -1,9 +1,17 @@
 .section .text
 .global spin_lock
 .global spin_release
+.global spin_lock_irqsave
+.global spin_release_irqrestore
 
 // TODO: maybe add some tracing to this so I know
 //       the locks that consume too much CPU time
+spin_lock_irqsave:
+    pushfq
+    popq %rax
+    movq %rax, (%rsi)
+    cli
+
 spin_lock:
     // %rdi - spinlock
     lock bts $1, (%rdi)
@@ -17,6 +25,13 @@ spin_lock:
     jnz 1b
     jmp spin_lock
 
+spin_release_irqrestore:
+    movq $0, (%rdi)
+    testq $(1 << 9), (%rsi)
+    jz 1f
+    sti
+1:
+    retq
 
 spin_release:
     movq $0, (%rdi)

sys/debug.c

@@ -160,9 +160,8 @@ void debugf(int level, const char *f, ...) {
 }
 
 void debugfv(int level, const char *fmt, va_list args) {
-    // FIXME Problem: if this code gets interrupted while
-    //       inside the locked region, the CPU freezes
-    spin_lock(&debug_spin);
+    uintptr_t irq;
+    spin_lock_irqsave(&debug_spin, &irq);
 
     char c;
     union {
@@ -295,6 +294,6 @@ void debugfv(int level, const char *fmt, va_list args) {
         ++fmt;
     }
 
-    spin_release(&debug_spin);
+    spin_release_irqrestore(&debug_spin, &irq);
 }