1 files changed, 213 insertions, 0 deletions

diff --git a/arch/x86/kernel/tls.c b/arch/x86/kernel/tls.c
new file mode 100644
index 000000000000..6dfd4e76661a
--- /dev/null
+++ b/arch/x86/kernel/tls.c
@@ -0,0 +1,213 @@
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/sched.h>
+#include <linux/user.h>
+#include <linux/regset.h>
+
+#include <asm/uaccess.h>
+#include <asm/desc.h>
+#include <asm/system.h>
+#include <asm/ldt.h>
+#include <asm/processor.h>
+#include <asm/proto.h>
+
+#include "tls.h"
+
+/*
+ * sys_alloc_thread_area: get a yet unused TLS descriptor index.
+ */
+static int get_free_idx(void)
+{
+        struct thread_struct *t = &current->thread;
+        int idx;
+
+        for (idx = 0; idx < GDT_ENTRY_TLS_ENTRIES; idx++)
+                if (desc_empty(&t->tls_array[idx]))
+                        return idx + GDT_ENTRY_TLS_MIN;
+        return -ESRCH;
+}
+
+static void set_tls_desc(struct task_struct *p, int idx,
+                         const struct user_desc *info, int n)
+{
+        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();
+
+        while (n-- > 0) {
+                if (LDT_empty(info))
+                        desc->a = desc->b = 0;
+                else
+                        fill_ldt(desc, info);
+                ++info;
+                ++desc;
+        }
+
+        if (t == &current->thread)
+                load_TLS(t, cpu);
+
+        put_cpu();
+}
+
+/*
+ * Set a given TLS descriptor:
+ */
+int do_set_thread_area(struct task_struct *p, int idx,
+                       struct user_desc __user *u_info,
+                       int can_allocate)
+{
+        struct user_desc info;
+
+        if (copy_from_user(&info, u_info, sizeof(info)))
+                return -EFAULT;
+
+        if (idx == -1)
+                idx = info.entry_number;
+
+        /*
+         * index -1 means the kernel should try to find and
+         * allocate an empty descriptor:
+         */
+        if (idx == -1 && can_allocate) {
+                idx = get_free_idx();
+                if (idx < 0)
+                        return idx;
+                if (put_user(idx, &u_info->entry_number))
+                        return -EFAULT;
+        }
+
+        if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX)
+                return -EINVAL;
+
+        set_tls_desc(p, idx, &info, 1);
+
+        return 0;
+}
+
+asmlinkage int sys_set_thread_area(struct user_desc __user *u_info)
+{
+        return do_set_thread_area(current, -1, u_info, 1);
+}
+
+
+/*
+ * Get the current Thread-Local Storage area:
+ */
+
+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 user_desc info;
+
+        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;
+
+        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;
+        return 0;
+}
+
+asmlinkage int sys_get_thread_area(struct user_desc __user *u_info)
+{
+        return do_get_thread_area(current, -1, u_info);
+}
+
+int regset_tls_active(struct task_struct *target,
+                      const struct user_regset *regset)
+{
+        struct thread_struct *t = &target->thread;
+        int n = GDT_ENTRY_TLS_ENTRIES;
+        while (n > 0 && desc_empty(&t->tls_array[n - 1]))
+                --n;
+        return n;
+}
+
+int regset_tls_get(struct task_struct *target, const struct user_regset *regset,
+                   unsigned int pos, unsigned int count,
+                   void *kbuf, void __user *ubuf)
+{
+        const struct desc_struct *tls;
+
+        if (pos > GDT_ENTRY_TLS_ENTRIES * sizeof(struct user_desc) ||
+            (pos % sizeof(struct user_desc)) != 0 ||
+            (count % sizeof(struct user_desc)) != 0)
+                return -EINVAL;
+
+        pos /= sizeof(struct user_desc);
+        count /= sizeof(struct user_desc);
+
+        tls = &target->thread.tls_array[pos];
+
+        if (kbuf) {
+                struct user_desc *info = kbuf;
+                while (count-- > 0)
+                        fill_user_desc(info++, GDT_ENTRY_TLS_MIN + pos++,
+                                       tls++);
+        } else {
+                struct user_desc __user *u_info = ubuf;
+                while (count-- > 0) {
+                        struct user_desc info;
+                        fill_user_desc(&info, GDT_ENTRY_TLS_MIN + pos++, tls++);
+                        if (__copy_to_user(u_info++, &info, sizeof(info)))
+                                return -EFAULT;
+                }
+        }
+
+        return 0;
+}
+
+int regset_tls_set(struct task_struct *target, const struct user_regset *regset,
+                   unsigned int pos, unsigned int count,
+                   const void *kbuf, const void __user *ubuf)
+{
+        struct user_desc infobuf[GDT_ENTRY_TLS_ENTRIES];
+        const struct user_desc *info;
+
+        if (pos > GDT_ENTRY_TLS_ENTRIES * sizeof(struct user_desc) ||
+            (pos % sizeof(struct user_desc)) != 0 ||
+            (count % sizeof(struct user_desc)) != 0)
+                return -EINVAL;
+
+        if (kbuf)
+                info = kbuf;
+        else if (__copy_from_user(infobuf, ubuf, count))
+                return -EFAULT;
+        else
+                info = infobuf;
+
+        set_tls_desc(target,
+                     GDT_ENTRY_TLS_MIN + (pos / sizeof(struct user_desc)),
+                     info, count / sizeof(struct user_desc));
+
+        return 0;
+}