x86/idt: Remove address argument from idt_invalidate()

There is no reason to specify any specific address to idt_invalidate(). It
looks mostly like an artifact of unifying code done differently by
accident. The most "sensible" address to set here is a NULL pointer -
virtual address zero, just as a visual marker.

This also makes it possible to mark the struct desc_ptr in idt_invalidate()
as static const.

Signed-off-by: H. Peter Anvin (Intel) <hpa@zytor.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20210519212154.511983-5-hpa@zytor.com

arch/x86/include/asm/desc.h

@@ -427,6 +427,6 @@ static inline void idt_setup_early_pf(void) { }
 static inline void idt_setup_ist_traps(void) { }
 #endif
 
-extern void idt_invalidate(void *addr);
+extern void idt_invalidate(void);
 
 #endif /* _ASM_X86_DESC_H */

arch/x86/kernel/idt.c

@@ -331,11 +331,10 @@ void __init idt_setup_early_handler(void)
 
 /**
  * idt_invalidate - Invalidate interrupt descriptor table
- * @addr:	The virtual address of the 'invalid' IDT
  */
-void idt_invalidate(void *addr)
+void idt_invalidate(void)
 {
-	struct desc_ptr idt = { .address = (unsigned long) addr, .size = 0 };
+	static const struct desc_ptr idt = { .address = 0, .size = 0 };
 
 	load_idt(&idt);
 }

arch/x86/kernel/machine_kexec_32.c

@@ -232,7 +232,7 @@ void machine_kexec(struct kimage *image)
 	 * The gdt & idt are now invalid.
 	 * If you want to load them you must set up your own idt & gdt.
 	 */
-	idt_invalidate(phys_to_virt(0));
+	idt_invalidate();
 	set_gdt(phys_to_virt(0), 0);
 
 	/* now call it */

arch/x86/kernel/reboot.c

@@ -669,7 +669,7 @@ static void native_machine_emergency_restart(void)
 			break;
 
 		case BOOT_TRIPLE:
-			idt_invalidate(NULL);
+			idt_invalidate();
 			__asm__ __volatile__("int3");
 
 			/* We're probably dead after this, but... */