x86: change FIRST_SYSTEM_VECTOR to a variable

The SGI UV system needs several more system vectors than a vanilla
x86_64 system.  Rather than burden the other archs with extra system
vectors that they don't use, change FIRST_SYSTEM_VECTOR to a variable,
so that it can be dynamic.

Signed-off-by: Alan Mayer <ajm@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

diff --git a/include/asm-x86/desc.h b/include/asm-x86/desc.h
index 268a012..b3875d4 100644
--- a/include/asm-x86/desc.h
+++ b/include/asm-x86/desc.h
@@ -311,6 +311,28 @@
 	_set_gate(n, GATE_INTERRUPT, addr, 0, 0, __KERNEL_CS);
 }
 
+#define SYS_VECTOR_FREE		0
+#define SYS_VECTOR_ALLOCED	1
+
+extern int first_system_vector;
+extern char system_vectors[];
+
+static inline void alloc_system_vector(int vector)
+{
+	if (system_vectors[vector] == SYS_VECTOR_FREE) {
+		system_vectors[vector] = SYS_VECTOR_ALLOCED;
+		if (first_system_vector > vector)
+			first_system_vector = vector;
+	} else
+		BUG();
+}
+
+static inline void alloc_intr_gate(unsigned int n, void *addr)
+{
+	alloc_system_vector(n);
+	set_intr_gate(n, addr);
+}
+
 /*
  * This routine sets up an interrupt gate at directory privilege level 3.
  */