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-rw-r--r--arch/x86/kernel/tls.c213
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 00000000000..6dfd4e76661
--- /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;
+}