rmode: add spin lock protecting long_to_real CS

Signed-off-by: Pawel Wieczorkiewicz <[email protected]>
KernelTestFramework · Feb 12, 2021 · 7d57dde · 7d57dde
1 parent 2fa7b76
commit 7d57dde
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diff --git a/arch/x86/boot/head.S b/arch/x86/boot/head.S
@@ -85,6 +85,8 @@ GLOBAL(_start)
     ljmp  $__KERN_CS64, $.Llong_mode
 
 ENTRY(prot_to_real)
+    /* FIXME: Add spinlock */
+
     lea   (boot_gdt_ptr), %eax
     push  %eax
     lea   (boot_idt_ptr), %eax

diff --git a/arch/x86/real_mode_func.c b/arch/x86/real_mode_func.c
@@ -27,17 +27,22 @@
 #include <lib.h>
 #include <percpu.h>
 #include <smp/smp.h>
+#include <spinlock.h>
 #include <traps.h>
 
 extern void _long_to_real(const void *gdt_ptr, const void *idt_ptr);
 
+static spinlock_t lock = SPINLOCK_INIT;
+
 /* FIXME: add real mode calling functionality */
 void long_to_real(void) {
+    spin_lock(&lock);
     percpu_t *percpu = get_percpu_page(smp_processor_id());
 
     dprintk("%s: Before call\n", __func__);
     _long_to_real(&percpu->gdt_ptr, &percpu->idt_ptr);
     dprintk("%s: After call\n", __func__);
+    spin_unlock(&lock);
 }
 
 void init_real_mode(void) { init_rmode_traps(); }