x86: x86 TLS desc_struct cleanup

This cleans up the TLS code to use struct desc_struct and to separate the
encoding and installation magic from the interface wrappers.

Signed-off-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

2 files changed, 54 insertions, 46 deletions

diff --git a/arch/x86/kernel/tls.c b/arch/x86/kernel/tls.c
index 98f428be8e8c..f11c92a3faac 100644
--- a/arch/x86/kernel/tls.c
+++ b/arch/x86/kernel/tls.c
@@ -24,6 +24,29 @@ static int get_free_idx(void)
         return -ESRCH;
 }
 
+static void set_tls_desc(struct task_struct *p, int idx,
+                         const struct user_desc *info)
+{
+        struct thread_struct *t = &p->thread;
+        struct desc_struct *desc = &t->tls_array[idx - GDT_ENTRY_TLS_MIN];
+        int cpu;
+
+        /*
+         * We must not get preempted while modifying the TLS.
+         */
+        cpu = get_cpu();
+
+        if (LDT_empty(info))
+                desc->a = desc->b = 0;
+        else
+                fill_ldt(desc, info);
+
+        if (t == &current->thread)
+                load_TLS(t, cpu);
+
+        put_cpu();
+}
+
 /*
  * Set a given TLS descriptor:
  */
@@ -31,10 +54,7 @@ int do_set_thread_area(struct task_struct *p, int idx,
                        struct user_desc __user *u_info,
                        int can_allocate)
 {
-        struct thread_struct *t = &p->thread;
         struct user_desc info;
-        u32 *desc;
-        int cpu;
 
         if (copy_from_user(&info, u_info, sizeof(info)))
                 return -EFAULT;
@@ -57,23 +77,8 @@ int do_set_thread_area(struct task_struct *p, int idx,
         if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX)
                 return -EINVAL;
 
-        desc = (u32 *) &t->tls_array[idx - GDT_ENTRY_TLS_MIN];
+        set_tls_desc(p, idx, &info);
 
-        /*
-         * We must not get preempted while modifying the TLS.
-         */
-        cpu = get_cpu();
-
-        if (LDT_empty(&info)) {
-                desc[0] = 0;
-                desc[1] = 0;
-        } else
-                fill_ldt((struct desc_struct *)desc, &info);
-
-        if (t == &current->thread)
-                load_TLS(t, cpu);
-
-        put_cpu();
         return 0;
 }
 
@@ -87,42 +92,38 @@ asmlinkage int sys_set_thread_area(struct user_desc __user *u_info)
  * Get the current Thread-Local Storage area:
  */
 
-#define GET_LIMIT(desc)         (((desc)[0] & 0x0ffff) | ((desc)[1] & 0xf0000))
-#define GET_32BIT(desc)         (((desc)[1] >> 22) & 1)
-#define GET_CONTENTS(desc)      (((desc)[1] >> 10) & 3)
-#define GET_WRITABLE(desc)      (((desc)[1] >>  9) & 1)
-#define GET_LIMIT_PAGES(desc)   (((desc)[1] >> 23) & 1)
-#define GET_PRESENT(desc)       (((desc)[1] >> 15) & 1)
-#define GET_USEABLE(desc)       (((desc)[1] >> 20) & 1)
-#define GET_LONGMODE(desc)      (((desc)[1] >> 21) & 1)
+static void fill_user_desc(struct user_desc *info, int idx,
+                           const struct desc_struct *desc)
+
+{
+        memset(info, 0, sizeof(*info));
+        info->entry_number = idx;
+        info->base_addr = get_desc_base(desc);
+        info->limit = get_desc_limit(desc);
+        info->seg_32bit = desc->d;
+        info->contents = desc->type >> 2;
+        info->read_exec_only = !(desc->type & 2);
+        info->limit_in_pages = desc->g;
+        info->seg_not_present = !desc->p;
+        info->useable = desc->avl;
+#ifdef CONFIG_X86_64
+        info->lm = desc->l;
+#endif
+}
 
 int do_get_thread_area(struct task_struct *p, int idx,
                        struct user_desc __user *u_info)
 {
-        struct thread_struct *t = &p->thread;
         struct user_desc info;
-        u32 *desc;
 
         if (idx == -1 && get_user(idx, &u_info->entry_number))
                 return -EFAULT;
+
         if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX)
                 return -EINVAL;
 
-        desc = (u32 *) &t->tls_array[idx - GDT_ENTRY_TLS_MIN];
-
-        memset(&info, 0, sizeof(struct user_desc));
-        info.entry_number = idx;
-        info.base_addr = get_desc_base((struct desc_struct *)desc);
-        info.limit = GET_LIMIT(desc);
-        info.seg_32bit = GET_32BIT(desc);
-        info.contents = GET_CONTENTS(desc);
-        info.read_exec_only = !GET_WRITABLE(desc);
-        info.limit_in_pages = GET_LIMIT_PAGES(desc);
-        info.seg_not_present = !GET_PRESENT(desc);
-        info.useable = GET_USEABLE(desc);
-#ifdef CONFIG_X86_64
-        info.lm = GET_LONGMODE(desc);
-#endif
+        fill_user_desc(&info, idx,
+                       &p->thread.tls_array[idx - GDT_ENTRY_TLS_MIN]);
 
         if (copy_to_user(u_info, &info, sizeof(info)))
                 return -EFAULT;
diff --git a/include/asm-x86/desc.h b/include/asm-x86/desc.h
index e17581ad8824..5b6a05d3a771 100644
--- a/include/asm-x86/desc.h
+++ b/include/asm-x86/desc.h
@@ -7,7 +7,8 @@
 #include <asm/mmu.h>
 #include <linux/smp.h>
 
-static inline void fill_ldt(struct desc_struct *desc, struct user_desc *info)
+static inline void fill_ldt(struct desc_struct *desc,
+                            const struct user_desc *info)
 {
         desc->limit0 = info->limit & 0x0ffff;
         desc->base0 = info->base_addr & 0x0000ffff;
@@ -275,10 +276,16 @@ static inline void load_LDT(mm_context_t *pc)
         preempt_enable();
 }
 
-static inline unsigned long get_desc_base(struct desc_struct *desc)
+static inline unsigned long get_desc_base(const struct desc_struct *desc)
 {
         return desc->base0 | ((desc->base1) << 16) | ((desc->base2) << 24);
 }
+
+static inline unsigned long get_desc_limit(const struct desc_struct *desc)
+{
+        return desc->limit0 | (desc->limit << 16);
+}
+
 static inline void _set_gate(int gate, unsigned type, void *addr,
                               unsigned dpl, unsigned ist, unsigned seg)
 {