smp: fix wakeups doing bad EOI write

kernel/arch/x86_64/irq.S

@@ -87,7 +87,8 @@ ISR_NOERR 127
 _isr126:
     pushq %r12
     mov (lapic_final), %r12
-    movq $0, 0xb0(%r12)
+    add $0xb0, %r12
+    movl $0, (%r12)
     popq %r12
     iretq
 

kernel/arch/x86_64/smp.c

@@ -289,11 +289,8 @@ void smp_initialize(void) {
 }
 
 void arch_wakeup_others(void) {
-	/* Never wake up BSP, don't hit ourselves, easy. */
-	for (int i = 1; i < processor_count; ++i) {
-		if (i == this_core->cpu_id) continue;
-		if (processor_local_data[i].current_process == processor_local_data[i].kernel_idle_task) {
-			lapic_send_ipi(processor_local_data[i].lapic_id, 0x407E);
-		}
-	}
+	/* Send broadcast IPI to others; this is a soft interrupt
+	 * that just nudges idle cores out of their HLT states.
+	 * It should be gentle enough that busy cores dont't care. */
+	lapic_send_ipi(0, 0x7E | (3 << 18));
 }

kernel/sys/process.c

@@ -293,8 +293,8 @@ static void _kidle(void) {
 
 static void _kburn(void) {
 	while (1) {
-		//arch_pause();
-		if (((volatile list_t *)process_queue)->head) switch_next();
+		arch_pause();
+		switch_next();
 	}
 }
 

kernel/sys/syscall.c

@@ -135,6 +135,10 @@ static long sys_sysfunc(long fn, char ** args) {
 			this_core->current_process->thread.context.tls_base = (uintptr_t)args[0];
 			arch_set_tls_base(this_core->current_process->thread.context.tls_base);
 			return 0;
+
+		case 99:
+			arch_wakeup_others();
+			return 0;
 		default:
 			printf("Bad system function: %ld\n", fn);
 			return -EINVAL;