1 files changed, 158 insertions, 0 deletions

diff --git a/arch/x86/kernel/tls.c b/arch/x86/kernel/tls.c
new file mode 100644
index 000000000000..5291596f19b0
--- /dev/null
+++ b/arch/x86/kernel/tls.c
@@ -0,0 +1,158 @@
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/sched.h>
+#include <linux/user.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>
+
+/*
+ * 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((struct n_desc_struct *)(t->tls_array) + idx))
+                        return idx + GDT_ENTRY_TLS_MIN;
+        return -ESRCH;
+}
+
+/*
+ * Set a given TLS descriptor:
+ * When you want addresses > 32bit use arch_prctl()
+ */
+int do_set_thread_area(struct thread_struct *t, struct user_desc __user *u_info)
+{
+        struct user_desc info;
+        struct n_desc_struct *desc;
+        int cpu, idx;
+
+        if (copy_from_user(&info, u_info, sizeof(info)))
+                return -EFAULT;
+
+        idx = info.entry_number;
+
+        /*
+         * index -1 means the kernel should try to find and
+         * allocate an empty descriptor:
+         */
+        if (idx == -1) {
+                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;
+
+        desc = ((struct n_desc_struct *)t->tls_array) + idx - GDT_ENTRY_TLS_MIN;
+
+        /*
+         * We must not get preempted while modifying the TLS.
+         */
+        cpu = get_cpu();
+
+        if (LDT_empty(&info)) {
+                desc->a = 0;
+                desc->b = 0;
+        } else {
+                desc->a = LDT_entry_a(&info);
+                desc->b = LDT_entry_b(&info);
+        }
+        if (t == &current->thread)
+                load_TLS(t, cpu);
+
+        put_cpu();
+        return 0;
+}
+
+asmlinkage long sys32_set_thread_area(struct user_desc __user *u_info)
+{
+        return do_set_thread_area(&current->thread, u_info);
+}
+
+
+/*
+ * Get the current Thread-Local Storage area:
+ */
+
+#define GET_LIMIT(desc) ( \
+        ((desc)->a & 0x0ffff) | \
+         ((desc)->b & 0xf0000) )
+
+#define GET_32BIT(desc)         (((desc)->b >> 22) & 1)
+#define GET_CONTENTS(desc)      (((desc)->b >> 10) & 3)
+#define GET_WRITABLE(desc)      (((desc)->b >>  9) & 1)
+#define GET_LIMIT_PAGES(desc)   (((desc)->b >> 23) & 1)
+#define GET_PRESENT(desc)       (((desc)->b >> 15) & 1)
+#define GET_USEABLE(desc)       (((desc)->b >> 20) & 1)
+#define GET_LONGMODE(desc)      (((desc)->b >> 21) & 1)
+
+int do_get_thread_area(struct thread_struct *t, struct user_desc __user *u_info)
+{
+        struct user_desc info;
+        struct n_desc_struct *desc;
+        int idx;
+
+        if (get_user(idx, &u_info->entry_number))
+                return -EFAULT;
+        if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX)
+                return -EINVAL;
+
+        desc = ((struct n_desc_struct *)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(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);
+        info.lm = GET_LONGMODE(desc);
+
+        if (copy_to_user(u_info, &info, sizeof(info)))
+                return -EFAULT;
+        return 0;
+}
+
+asmlinkage long sys32_get_thread_area(struct user_desc __user *u_info)
+{
+        return do_get_thread_area(&current->thread, u_info);
+}
+
+
+int ia32_child_tls(struct task_struct *p, struct pt_regs *childregs)
+{
+        struct n_desc_struct *desc;
+        struct user_desc info;
+        struct user_desc __user *cp;
+        int idx;
+
+        cp = (void __user *)childregs->rsi;
+        if (copy_from_user(&info, cp, sizeof(info)))
+                return -EFAULT;
+        if (LDT_empty(&info))
+                return -EINVAL;
+
+        idx = info.entry_number;
+        if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX)
+                return -EINVAL;
+
+        desc = (struct n_desc_struct *)(p->thread.tls_array) + idx - GDT_ENTRY_TLS_MIN;
+        desc->a = LDT_entry_a(&info);
+        desc->b = LDT_entry_b(&info);
+
+        return 0;
+}