x86/ldttss: Clean up 32-bit descriptors

Like the IDT descriptors, the LDT/TSS descriptors are pointlessly different
on 32 and 64 bit kernels.

Unify them and get rid of the duplicated code.

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/20170828064958.289634692@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/include/asm/desc.h

@@ -166,42 +166,22 @@ native_write_gdt_entry(struct desc_struct *gdt, int entry, const void *desc, int
 	memcpy(&gdt[entry], desc, size);
 }
 
-static inline void pack_descriptor(struct desc_struct *desc, unsigned long base,
-				   unsigned long limit, unsigned char type,
-				   unsigned char flags)
-{
-	desc->limit0		= (u16) limit;
-	desc->base0		= (u16) base;
-	desc->base1		= (base >> 16) & 0xFF;
-	desc->type		= type & 0x0F;
-	desc->s			= 0;
-	desc->dpl		= 0;
-	desc->p			= 1;
-	desc->limit1		= (limit >> 16) & 0xF;
-	desc->avl		= (flags >> 0) & 0x01;
-	desc->l			= (flags >> 1) & 0x01;
-	desc->d			= (flags >> 2) & 0x01;
-	desc->g			= (flags >> 3) & 0x01;
-}
-
 static inline void set_tssldt_descriptor(void *d, unsigned long addr,
 					 unsigned type, unsigned size)
 {
-#ifdef CONFIG_X86_64
-	struct ldttss_desc64 *desc = d;
+	struct ldttss_desc *desc = d;
 
 	memset(desc, 0, sizeof(*desc));
 
-	desc->limit0		= size & 0xFFFF;
+	desc->limit0		= (u16) size;
 	desc->base0		= (u16) addr;
 	desc->base1		= (addr >> 16) & 0xFF;
 	desc->type		= type;
 	desc->p			= 1;
 	desc->limit1		= (size >> 16) & 0xF;
 	desc->base2		= (addr >> 24) & 0xFF;
+#ifdef CONFIG_X86_64
 	desc->base3		= (u32) (addr >> 32);
-#else
-	pack_descriptor((struct desc_struct *)d, addr, size, type, 0);
 #endif
 }
 

arch/x86/include/asm/desc_defs.h

@@ -49,24 +49,21 @@ enum {
 	DESCTYPE_S = 0x10,	/* !system */
 };
 
-/* LDT or TSS descriptor in the GDT. 16 bytes. */
-struct ldttss_desc64 {
-	u16 limit0;
-	u16 base0;
-	unsigned base1 : 8, type : 5, dpl : 2, p : 1;
-	unsigned limit1 : 4, zero0 : 3, g : 1, base2 : 8;
-	u32 base3;
-	u32 zero1;
-} __attribute__((packed));
-
+/* LDT or TSS descriptor in the GDT. */
+struct ldttss_desc {
+	u16	limit0;
+	u16	base0;
 
+	u16	base1 : 8, type : 5, dpl : 2, p : 1;
+	u16	limit1 : 4, zero0 : 3, g : 1, base2 : 8;
 #ifdef CONFIG_X86_64
-typedef struct ldttss_desc64 ldt_desc;
-typedef struct ldttss_desc64 tss_desc;
-#else
-typedef struct desc_struct ldt_desc;
-typedef struct desc_struct tss_desc;
+	u32	base3;
+	u32	zero1;
 #endif
+} __attribute__((packed));
+
+typedef struct ldttss_desc ldt_desc;
+typedef struct ldttss_desc tss_desc;
 
 struct idt_bits {
 	u16		ist	: 3,