x86/idt: Create file for IDT related code

IDT related code lives scattered around in various places. Create a new
source file in arch/x86/kernel/idt.c to hold it.

Move the idt_tables and descriptors to it for a start. Follow up patches
will gradually move more code over.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/20170828064958.367081121@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/kernel/Makefile

@@ -42,7 +42,7 @@ CFLAGS_irq.o := -I$(src)/../include/asm/trace
 
 obj-y			:= process_$(BITS).o signal.o
 obj-$(CONFIG_COMPAT)	+= signal_compat.o
-obj-y			+= traps.o irq.o irq_$(BITS).o dumpstack_$(BITS).o
+obj-y			+= traps.o idt.o irq.o irq_$(BITS).o dumpstack_$(BITS).o
 obj-y			+= time.o ioport.o dumpstack.o nmi.o
 obj-$(CONFIG_MODIFY_LDT_SYSCALL)	+= ldt.o
 obj-y			+= setup.o x86_init.o i8259.o irqinit.o jump_label.o

arch/x86/kernel/cpu/common.c

@@ -1289,15 +1289,6 @@ static __init int setup_disablecpuid(char *arg)
 __setup("clearcpuid=", setup_disablecpuid);
 
 #ifdef CONFIG_X86_64
-struct desc_ptr idt_descr __ro_after_init = {
-	.size = NR_VECTORS * 16 - 1,
-	.address = (unsigned long) idt_table,
-};
-const struct desc_ptr debug_idt_descr = {
-	.size = NR_VECTORS * 16 - 1,
-	.address = (unsigned long) debug_idt_table,
-};
-
 DEFINE_PER_CPU_FIRST(union irq_stack_union,
 		     irq_stack_union) __aligned(PAGE_SIZE) __visible;
 

arch/x86/kernel/idt.c

@@ -0,0 +1,26 @@
+/*
+ * Interrupt descriptor table related code
+ *
+ * This file is licensed under the GPL V2
+ */
+#include <linux/interrupt.h>
+
+#include <asm/desc.h>
+
+/* Must be page-aligned because the real IDT is used in a fixmap. */
+gate_desc idt_table[IDT_ENTRIES] __page_aligned_bss;
+
+#ifdef CONFIG_X86_64
+/* No need to be aligned, but done to keep all IDTs defined the same way. */
+gate_desc debug_idt_table[IDT_ENTRIES] __page_aligned_bss;
+
+struct desc_ptr idt_descr __ro_after_init = {
+	.size		= IDT_ENTRIES * 16 - 1,
+	.address	= (unsigned long) idt_table,
+};
+
+const struct desc_ptr debug_idt_descr = {
+	.size		= IDT_ENTRIES * 16 - 1,
+	.address	= (unsigned long) debug_idt_table,
+};
+#endif

arch/x86/kernel/traps.c

@@ -65,18 +65,12 @@
 #include <asm/x86_init.h>
 #include <asm/pgalloc.h>
 #include <asm/proto.h>
-
-/* No need to be aligned, but done to keep all IDTs defined the same way. */
-gate_desc debug_idt_table[NR_VECTORS] __page_aligned_bss;
 #else
 #include <asm/processor-flags.h>
 #include <asm/setup.h>
 #include <asm/proto.h>
 #endif
 
-/* Must be page-aligned because the real IDT is used in a fixmap. */
-gate_desc idt_table[NR_VECTORS] __page_aligned_bss;
-
 DECLARE_BITMAP(used_vectors, NR_VECTORS);
 
 static inline void cond_local_irq_enable(struct pt_regs *regs)