x86: introduce fill_ldt

This patch introduces fill_ldt(), which populates a ldt descriptor
from a user_desc in once, instead of relying in the LDT_entry_a and
LDT_entry_b macros

Signed-off-by: Glauber de Oliveira Costa <gcosta@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

arch/x86/kernel/ldt.c

@@ -223,8 +223,7 @@ static int write_ldt(void __user *ptr, unsigned long bytecount, int oldmode)
 		}
 	}
 
-	ldt.a = LDT_entry_a(&ldt_info);
-	ldt.b = LDT_entry_b(&ldt_info);
+	fill_ldt(&ldt, &ldt_info);
 	if (oldmode)
 		ldt.avl = 0;
 

arch/x86/kernel/process_64.c

@@ -457,8 +457,7 @@ static inline void set_32bit_tls(struct task_struct *t, int tls, u32 addr)
 	};
 	struct desc_struct *desc = (void *)t->thread.tls_array;
 	desc += tls;
-	desc->a = LDT_entry_a(&ud);
-	desc->b = LDT_entry_b(&ud);
+	fill_ldt(desc, &ud);
 }
 
 static inline u32 read_32bit_tls(struct task_struct *t, int tls)

arch/x86/kernel/tls.c

@@ -67,10 +67,9 @@ int do_set_thread_area(struct task_struct *p, int idx,
 	if (LDT_empty(&info)) {
 		desc[0] = 0;
 		desc[1] = 0;
-	} else {
-		desc[0] = LDT_entry_a(&info);
-		desc[1] = LDT_entry_b(&info);
-	}
+	} else
+		fill_ldt((struct desc_struct *)desc, &info);
+
 	if (t == &current->thread)
 		load_TLS(t, cpu);
 

include/asm-x86/desc.h

@@ -1,5 +1,34 @@
+#ifndef _ASM_DESC_H_
+#define _ASM_DESC_H_
+
+#ifndef __ASSEMBLY__
+#include <asm/desc_defs.h>
+#include <asm/ldt.h>
+
+static inline void fill_ldt(struct desc_struct *desc, struct user_desc *info)
+{
+	desc->limit0 = info->limit & 0x0ffff;
+	desc->base0 = info->base_addr & 0x0000ffff;
+
+	desc->base1 = (info->base_addr & 0x00ff0000) >> 16;
+	desc->type = (info->read_exec_only ^ 1) << 1;
+	desc->type |= info->contents << 2;
+	desc->s = 1;
+	desc->dpl = 0x3;
+	desc->p = info->seg_not_present ^ 1;
+	desc->limit = (info->limit & 0xf0000) >> 16;
+	desc->avl = info->useable;
+	desc->d = info->seg_32bit;
+	desc->g = info->limit_in_pages;
+	desc->base2 = (info->base_addr & 0xff000000) >> 24;
+}
+
+#endif
+
 #ifdef CONFIG_X86_32
 # include "desc_32.h"
 #else
 # include "desc_64.h"
 #endif
+
+#endif

include/asm-x86/desc_32.h

@@ -163,21 +163,6 @@ static inline void __set_tss_desc(unsigned int cpu, unsigned int entry, const vo
 
 #define set_tss_desc(cpu,addr) __set_tss_desc(cpu, GDT_ENTRY_TSS, addr)
 
-#define LDT_entry_a(info) \
-	((((info)->base_addr & 0x0000ffff) << 16) | ((info)->limit & 0x0ffff))
-
-#define LDT_entry_b(info) \
-	(((info)->base_addr & 0xff000000) | \
-	(((info)->base_addr & 0x00ff0000) >> 16) | \
-	((info)->limit & 0xf0000) | \
-	(((info)->read_exec_only ^ 1) << 9) | \
-	((info)->contents << 10) | \
-	(((info)->seg_not_present ^ 1) << 15) | \
-	((info)->seg_32bit << 22) | \
-	((info)->limit_in_pages << 23) | \
-	((info)->useable << 20) | \
-	0x7000)
-
 #define LDT_empty(info) (\
 	(info)->base_addr	== 0	&& \
 	(info)->limit		== 0	&& \

include/asm-x86/desc_64.h

@@ -147,23 +147,6 @@ static inline void set_ldt_desc(unsigned cpu, void *addr, int size)
 			     (unsigned long)addr, DESC_LDT, size * 8 - 1);
 }
 
-#define LDT_entry_a(info) \
-	((((info)->base_addr & 0x0000ffff) << 16) | ((info)->limit & 0x0ffff))
-/* Don't allow setting of the lm bit. It is useless anyways because
-   64bit system calls require __USER_CS. */
-#define LDT_entry_b(info) \
-	(((info)->base_addr & 0xff000000) | \
-	(((info)->base_addr & 0x00ff0000) >> 16) | \
-	((info)->limit & 0xf0000) | \
-	(((info)->read_exec_only ^ 1) << 9) | \
-	((info)->contents << 10) | \
-	(((info)->seg_not_present ^ 1) << 15) | \
-	((info)->seg_32bit << 22) | \
-	((info)->limit_in_pages << 23) | \
-	((info)->useable << 20) | \
-	/* ((info)->lm << 21) | */ \
-	0x7000)
-
 #define LDT_empty(info) (\
 	(info)->base_addr	== 0	&& \
 	(info)->limit		== 0	&& \