[PATCH] Fix TSS limit on x86-64

The limit of the TSS segment was incorrectly set to a too big value
on x86-64. This lead to the CPU reading random memory behind the main
TSS when iopl was >0, but there was no ioperm bitmap set. This caused
random failures in port accesses in this state.

Set the correct limit.

include/asm-x86_64/desc.h

@@ -118,7 +118,7 @@ static inline void set_tssldt_descriptor(void *ptr, unsigned long tss, unsigned
 	d.base1 = PTR_MIDDLE(tss) & 0xFF; 
 	d.type = type;
 	d.p = 1; 
-	d.limit1 = 0xF;
+	d.limit1 = (size >> 16) & 0xF;
 	d.base2 = (PTR_MIDDLE(tss) >> 8) & 0xFF; 
 	d.base3 = PTR_HIGH(tss); 
 	memcpy(ptr, &d, 16);