diff --git a/arch/um/include/os.h b/arch/um/include/os.h
index 5fb84e8..e9e1db1 100644
--- a/arch/um/include/os.h
+++ b/arch/um/include/os.h
@@ -236,6 +236,10 @@
 			     int stack_order);
 extern int helper_wait(int pid);
 
+
+/* tls.c */
+extern int os_set_thread_area(void *data, int pid);
+extern int os_get_thread_area(void *data, int pid);
 /* umid.c */
 
 extern int umid_file_name(char *name, char *buf, int len);
diff --git a/arch/um/kernel/exec_kern.c b/arch/um/kernel/exec_kern.c
index f9b346e..c0cb627 100644
--- a/arch/um/kernel/exec_kern.c
+++ b/arch/um/kernel/exec_kern.c
@@ -22,6 +22,7 @@
 
 void flush_thread(void)
 {
+	arch_flush_thread(&current->thread.arch);
 	CHOOSE_MODE(flush_thread_tt(), flush_thread_skas());
 }
 
@@ -74,14 +75,3 @@
 	unlock_kernel();
 	return(error);
 }
-
-/*
- * Overrides for Emacs so that we follow Linus's tabbing style.
- * Emacs will notice this stuff at the end of the file and automatically
- * adjust the settings for this buffer only.  This must remain at the end
- * of the file.
- * ---------------------------------------------------------------------------
- * Local variables:
- * c-file-style: "linux"
- * End:
- */
diff --git a/arch/um/kernel/process_kern.c b/arch/um/kernel/process_kern.c
index ba8a52c..f6a5a50 100644
--- a/arch/um/kernel/process_kern.c
+++ b/arch/um/kernel/process_kern.c
@@ -156,9 +156,25 @@
 		unsigned long stack_top, struct task_struct * p, 
 		struct pt_regs *regs)
 {
+	int ret;
+
 	p->thread = (struct thread_struct) INIT_THREAD;
-	return(CHOOSE_MODE_PROC(copy_thread_tt, copy_thread_skas, nr, 
-				clone_flags, sp, stack_top, p, regs));
+	ret = CHOOSE_MODE_PROC(copy_thread_tt, copy_thread_skas, nr,
+				clone_flags, sp, stack_top, p, regs);
+
+	if (ret || !current->thread.forking)
+		goto out;
+
+	clear_flushed_tls(p);
+
+	/*
+	 * Set a new TLS for the child thread?
+	 */
+	if (clone_flags & CLONE_SETTLS)
+		ret = arch_copy_tls(p);
+
+out:
+	return ret;
 }
 
 void initial_thread_cb(void (*proc)(void *), void *arg)
diff --git a/arch/um/kernel/ptrace.c b/arch/um/kernel/ptrace.c
index 3945822..60d2eda 100644
--- a/arch/um/kernel/ptrace.c
+++ b/arch/um/kernel/ptrace.c
@@ -185,6 +185,16 @@
 		ret = set_fpxregs(data, child);
 		break;
 #endif
+	case PTRACE_GET_THREAD_AREA:
+		ret = ptrace_get_thread_area(child, addr,
+					     (struct user_desc __user *) data);
+		break;
+
+	case PTRACE_SET_THREAD_AREA:
+		ret = ptrace_set_thread_area(child, addr,
+					     (struct user_desc __user *) data);
+		break;
+
 	case PTRACE_FAULTINFO: {
 		/* Take the info from thread->arch->faultinfo,
 		 * but transfer max. sizeof(struct ptrace_faultinfo).
diff --git a/arch/um/kernel/skas/process_kern.c b/arch/um/kernel/skas/process_kern.c
index 14360ac..38b1853 100644
--- a/arch/um/kernel/skas/process_kern.c
+++ b/arch/um/kernel/skas/process_kern.c
@@ -111,6 +111,8 @@
 		if(sp != 0) REGS_SP(p->thread.regs.regs.skas.regs) = sp;
 
 		handler = fork_handler;
+
+		arch_copy_thread(&current->thread.arch, &p->thread.arch);
 	}
 	else {
 		init_thread_registers(&p->thread.regs.regs);
diff --git a/arch/um/os-Linux/Makefile b/arch/um/os-Linux/Makefile
index 9e0788c..f4bfc4c 100644
--- a/arch/um/os-Linux/Makefile
+++ b/arch/um/os-Linux/Makefile
@@ -4,7 +4,7 @@
 #
 
 obj-y = aio.o elf_aux.o file.o helper.o irq.o main.o mem.o process.o sigio.o \
-	signal.o start_up.o time.o trap.o tt.o tty.o uaccess.o umid.o \
+	signal.o start_up.o time.o trap.o tt.o tty.o uaccess.o umid.o tls.o \
 	user_syms.o util.o drivers/ sys-$(SUBARCH)/
 
 obj-$(CONFIG_MODE_SKAS) += skas/
@@ -12,7 +12,7 @@
 user-objs-$(CONFIG_TTY_LOG) += tty_log.o
 
 USER_OBJS := $(user-objs-y) aio.o elf_aux.o file.o helper.o irq.o main.o mem.o \
-	process.o sigio.o signal.o start_up.o time.o trap.o tt.o tty.o \
+	process.o sigio.o signal.o start_up.o time.o trap.o tt.o tty.o tls.o \
 	uaccess.o umid.o util.o
 
 CFLAGS_user_syms.o += -DSUBARCH_$(SUBARCH)
diff --git a/arch/um/os-Linux/tls.c b/arch/um/os-Linux/tls.c
new file mode 100644
index 0000000..63dfcf7
--- /dev/null
+++ b/arch/um/os-Linux/tls.c
@@ -0,0 +1,77 @@
+#include <errno.h>
+#include <sys/ptrace.h>
+#include <asm/ldt.h>
+#include "uml-config.h"
+
+/* TLS support - we basically rely on the host's one.*/
+
+/* In TT mode, this should be called only by the tracing thread, and makes sense
+ * only for PTRACE_SET_THREAD_AREA. In SKAS mode, it's used normally.
+ *
+ */
+
+#ifndef PTRACE_GET_THREAD_AREA
+#define PTRACE_GET_THREAD_AREA 25
+#endif
+
+#ifndef PTRACE_SET_THREAD_AREA
+#define PTRACE_SET_THREAD_AREA 26
+#endif
+
+int os_set_thread_area(void *data, int pid)
+{
+	struct user_desc *info = data;
+	int ret;
+
+	ret = ptrace(PTRACE_SET_THREAD_AREA, pid, info->entry_number,
+		     (unsigned long) info);
+	if (ret < 0)
+		ret = -errno;
+	return ret;
+}
+
+#ifdef UML_CONFIG_MODE_SKAS
+
+int os_get_thread_area(void *data, int pid)
+{
+	struct user_desc *info = data;
+	int ret;
+
+	ret = ptrace(PTRACE_GET_THREAD_AREA, pid, info->entry_number,
+		     (unsigned long) info);
+	if (ret < 0)
+		ret = -errno;
+	return ret;
+}
+
+#endif
+
+#ifdef UML_CONFIG_MODE_TT
+#include "linux/unistd.h"
+
+_syscall1(int, get_thread_area, struct user_desc *, u_info);
+_syscall1(int, set_thread_area, struct user_desc *, u_info);
+
+int do_set_thread_area_tt(struct user_desc *info)
+{
+	int ret;
+
+	ret = set_thread_area(info);
+	if (ret < 0) {
+		ret = -errno;
+	}
+	return ret;
+}
+
+int do_get_thread_area_tt(struct user_desc *info)
+{
+	int ret;
+
+	ret = get_thread_area(info);
+	if (ret < 0) {
+		ret = -errno;
+	}
+	return ret;
+}
+
+#endif /* UML_CONFIG_MODE_TT */
diff --git a/arch/um/sys-i386/Makefile b/arch/um/sys-i386/Makefile
index 2c06a07..98b20b7 100644
--- a/arch/um/sys-i386/Makefile
+++ b/arch/um/sys-i386/Makefile
@@ -1,5 +1,6 @@
 obj-y = bugs.o checksum.o delay.o fault.o ksyms.o ldt.o ptrace.o \
-	ptrace_user.o signal.o sigcontext.o syscalls.o sysrq.o sys_call_table.o
+	ptrace_user.o signal.o sigcontext.o syscalls.o sysrq.o \
+	sys_call_table.o tls.o
 
 obj-$(CONFIG_MODE_SKAS) += stub.o stub_segv.o
 
diff --git a/arch/um/sys-i386/ptrace.c b/arch/um/sys-i386/ptrace.c
index 927fcd9..6a23cc6 100644
--- a/arch/um/sys-i386/ptrace.c
+++ b/arch/um/sys-i386/ptrace.c
@@ -18,10 +18,12 @@
 void arch_switch_to_tt(struct task_struct *from, struct task_struct *to)
 {
 	update_debugregs(to->thread.arch.debugregs_seq);
+	arch_switch_tls_tt(from, to);
 }
 
 void arch_switch_to_skas(struct task_struct *from, struct task_struct *to)
 {
+	arch_switch_tls_skas(from, to);
 }
 
 int is_syscall(unsigned long addr)
diff --git a/arch/um/sys-i386/sys_call_table.S b/arch/um/sys-i386/sys_call_table.S
index ad75c27..1ff6147 100644
--- a/arch/um/sys-i386/sys_call_table.S
+++ b/arch/um/sys-i386/sys_call_table.S
@@ -6,8 +6,6 @@
 
 #define sys_vm86old sys_ni_syscall
 #define sys_vm86 sys_ni_syscall
-#define sys_set_thread_area sys_ni_syscall
-#define sys_get_thread_area sys_ni_syscall
 
 #define sys_stime um_stime
 #define sys_time um_time
diff --git a/arch/um/sys-i386/syscalls.c b/arch/um/sys-i386/syscalls.c
index 1845123..749dd1b 100644
--- a/arch/um/sys-i386/syscalls.c
+++ b/arch/um/sys-i386/syscalls.c
@@ -61,21 +61,27 @@
 	return sys_select(a.n, a.inp, a.outp, a.exp, a.tvp);
 }
 
-/* The i386 version skips reading from %esi, the fourth argument. So we must do
- * this, too.
+/*
+ * The prototype on i386 is:
+ *
+ *     int clone(int flags, void * child_stack, int * parent_tidptr, struct user_desc * newtls, int * child_tidptr)
+ *
+ * and the "newtls" arg. on i386 is read by copy_thread directly from the
+ * register saved on the stack.
  */
 long sys_clone(unsigned long clone_flags, unsigned long newsp,
-	       int __user *parent_tid, int unused, int __user *child_tid)
+	       int __user *parent_tid, void *newtls, int __user *child_tid)
 {
 	long ret;
 
 	if (!newsp)
 		newsp = UPT_SP(&current->thread.regs.regs);
+
 	current->thread.forking = 1;
 	ret = do_fork(clone_flags, newsp, &current->thread.regs, 0, parent_tid,
 		      child_tid);
 	current->thread.forking = 0;
-	return(ret);
+	return ret;
 }
 
 /*
diff --git a/arch/um/sys-i386/tls.c b/arch/um/sys-i386/tls.c
new file mode 100644
index 0000000..e3c5bc5
--- /dev/null
+++ b/arch/um/sys-i386/tls.c
@@ -0,0 +1,326 @@
+/*
+ * Copyright (C) 2005 Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
+ * Licensed under the GPL
+ */
+
+#include "linux/config.h"
+#include "linux/kernel.h"
+#include "linux/sched.h"
+#include "linux/slab.h"
+#include "linux/types.h"
+#include "asm/uaccess.h"
+#include "asm/ptrace.h"
+#include "asm/segment.h"
+#include "asm/smp.h"
+#include "asm/desc.h"
+#include "choose-mode.h"
+#include "kern.h"
+#include "kern_util.h"
+#include "mode_kern.h"
+#include "os.h"
+#include "mode.h"
+
+#ifdef CONFIG_MODE_SKAS
+#include "skas.h"
+#endif
+
+#ifdef CONFIG_MODE_SKAS
+int do_set_thread_area_skas(struct user_desc *info)
+{
+	int ret;
+	u32 cpu;
+
+	cpu = get_cpu();
+	ret = os_set_thread_area(info, userspace_pid[cpu]);
+	put_cpu();
+	return ret;
+}
+
+int do_get_thread_area_skas(struct user_desc *info)
+{
+	int ret;
+	u32 cpu;
+
+	cpu = get_cpu();
+	ret = os_get_thread_area(info, userspace_pid[cpu]);
+	put_cpu();
+	return ret;
+}
+#endif
+
+/*
+ * sys_get_thread_area: get a yet unused TLS descriptor index.
+ * XXX: Consider leaving one free slot for glibc usage at first place. This must
+ * be done here (and by changing GDT_ENTRY_TLS_* macros) and nowhere else.
+ *
+ * Also, this must be tested when compiling in SKAS mode with dinamic linking
+ * and running against NPTL.
+ */
+static int get_free_idx(struct task_struct* task)
+{
+	struct thread_struct *t = &task->thread;
+	int idx;
+
+	if (!t->arch.tls_array)
+		return GDT_ENTRY_TLS_MIN;
+
+	for (idx = 0; idx < GDT_ENTRY_TLS_ENTRIES; idx++)
+		if (!t->arch.tls_array[idx].present)
+			return idx + GDT_ENTRY_TLS_MIN;
+	return -ESRCH;
+}
+
+#define O_FORCE 1
+
+static inline void clear_user_desc(struct user_desc* info)
+{
+	/* Postcondition: LDT_empty(info) returns true. */
+	memset(info, 0, sizeof(*info));
+
+	/* Check the LDT_empty or the i386 sys_get_thread_area code - we obtain
+	 * indeed an empty user_desc.
+	 */
+	info->read_exec_only = 1;
+	info->seg_not_present = 1;
+}
+
+static int load_TLS(int flags, struct task_struct *to)
+{
+	int ret = 0;
+	int idx;
+
+	for (idx = GDT_ENTRY_TLS_MIN; idx < GDT_ENTRY_TLS_MAX; idx++) {
+		struct uml_tls_struct* curr = &to->thread.arch.tls_array[idx - GDT_ENTRY_TLS_MIN];
+
+		/* Actually, now if it wasn't flushed it gets cleared and
+		 * flushed to the host, which will clear it.*/
+		if (!curr->present) {
+			if (!curr->flushed) {
+				clear_user_desc(&curr->tls);
+				curr->tls.entry_number = idx;
+			} else {
+				WARN_ON(!LDT_empty(&curr->tls));
+				continue;
+			}
+		}
+
+		if (!(flags & O_FORCE) && curr->flushed)
+			continue;
+
+		ret = do_set_thread_area(&curr->tls);
+		if (ret)
+			goto out;
+
+		curr->flushed = 1;
+	}
+out:
+	return ret;
+}
+
+/* Verify if we need to do a flush for the new process, i.e. if there are any
+ * present desc's, only if they haven't been flushed.
+ */
+static inline int needs_TLS_update(struct task_struct *task)
+{
+	int i;
+	int ret = 0;
+
+	for (i = GDT_ENTRY_TLS_MIN; i < GDT_ENTRY_TLS_MAX; i++) {
+		struct uml_tls_struct* curr = &task->thread.arch.tls_array[i - GDT_ENTRY_TLS_MIN];
+
+		/* Can't test curr->present, we may need to clear a descriptor
+		 * which had a value. */
+		if (curr->flushed)
+			continue;
+		ret = 1;
+		break;
+	}
+	return ret;
+}
+
+/* On a newly forked process, the TLS descriptors haven't yet been flushed. So
+ * we mark them as such and the first switch_to will do the job.
+ */
+void clear_flushed_tls(struct task_struct *task)
+{
+	int i;
+
+	for (i = GDT_ENTRY_TLS_MIN; i < GDT_ENTRY_TLS_MAX; i++) {
+		struct uml_tls_struct* curr = &task->thread.arch.tls_array[i - GDT_ENTRY_TLS_MIN];
+
+		/* Still correct to do this, if it wasn't present on the host it
+		 * will remain as flushed as it was. */
+		if (!curr->present)
+			continue;
+
+		curr->flushed = 0;
+	}
+}
+
+/* This in SKAS0 does not need to be used, since we have different host
+ * processes. Nor will this need to be used when we'll add support to the host
+ * SKAS patch. */
+int arch_switch_tls_skas(struct task_struct *from, struct task_struct *to)
+{
+	return load_TLS(O_FORCE, to);
+}
+
+int arch_switch_tls_tt(struct task_struct *from, struct task_struct *to)
+{
+	if (needs_TLS_update(to))
+		return load_TLS(0, to);
+
+	return 0;
+}
+
+static int set_tls_entry(struct task_struct* task, struct user_desc *info,
+			 int idx, int flushed)
+{
+	struct thread_struct *t = &task->thread;
+
+	if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX)
+		return -EINVAL;
+
+	t->arch.tls_array[idx - GDT_ENTRY_TLS_MIN].tls = *info;
+	t->arch.tls_array[idx - GDT_ENTRY_TLS_MIN].present = 1;
+	t->arch.tls_array[idx - GDT_ENTRY_TLS_MIN].flushed = flushed;
+
+	return 0;
+}
+
+int arch_copy_tls(struct task_struct *new)
+{
+	struct user_desc info;
+	int idx, ret = -EFAULT;
+
+	if (copy_from_user(&info,
+			   (void __user *) UPT_ESI(&new->thread.regs.regs),
+			   sizeof(info)))
+		goto out;
+
+	ret = -EINVAL;
+	if (LDT_empty(&info))
+		goto out;
+
+	idx = info.entry_number;
+
+	ret = set_tls_entry(new, &info, idx, 0);
+out:
+	return ret;
+}
+
+/* XXX: use do_get_thread_area to read the host value? I'm not at all sure! */
+static int get_tls_entry(struct task_struct* task, struct user_desc *info, int idx)
+{
+	struct thread_struct *t = &task->thread;
+
+	if (!t->arch.tls_array)
+		goto clear;
+
+	if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX)
+		return -EINVAL;
+
+	if (!t->arch.tls_array[idx - GDT_ENTRY_TLS_MIN].present)
+		goto clear;
+
+	*info = t->arch.tls_array[idx - GDT_ENTRY_TLS_MIN].tls;
+
+out:
+	/* Temporary debugging check, to make sure that things have been
+	 * flushed. This could be triggered if load_TLS() failed.
+	 */
+	if (unlikely(task == current && !t->arch.tls_array[idx - GDT_ENTRY_TLS_MIN].flushed)) {
+		printk(KERN_ERR "get_tls_entry: task with pid %d got here "
+				"without flushed TLS.", current->pid);
+	}
+
+	return 0;
+clear:
+	/* When the TLS entry has not been set, the values read to user in the
+	 * tls_array are 0 (because it's cleared at boot, see
+	 * arch/i386/kernel/head.S:cpu_gdt_table). Emulate that.
+	 */
+	clear_user_desc(info);
+	info->entry_number = idx;
+	goto out;
+}
+
+asmlinkage int sys_set_thread_area(struct user_desc __user *user_desc)
+{
+	struct user_desc info;
+	int idx, ret;
+
+	if (copy_from_user(&info, user_desc, sizeof(info)))
+		return -EFAULT;
+
+	idx = info.entry_number;
+
+	if (idx == -1) {
+		idx = get_free_idx(current);
+		if (idx < 0)
+			return idx;
+		info.entry_number = idx;
+		/* Tell the user which slot we chose for him.*/
+		if (put_user(idx, &user_desc->entry_number))
+			return -EFAULT;
+	}
+
+	ret = CHOOSE_MODE_PROC(do_set_thread_area_tt, do_set_thread_area_skas, &info);
+	if (ret)
+		return ret;
+	return set_tls_entry(current, &info, idx, 1);
+}
+
+/*
+ * Perform set_thread_area on behalf of the traced child.
+ * Note: error handling is not done on the deferred load, and this differ from
+ * i386. However the only possible error are caused by bugs.
+ */
+int ptrace_set_thread_area(struct task_struct *child, int idx,
+		struct user_desc __user *user_desc)
+{
+	struct user_desc info;
+
+	if (copy_from_user(&info, user_desc, sizeof(info)))
+		return -EFAULT;
+
+	return set_tls_entry(child, &info, idx, 0);
+}
+
+asmlinkage int sys_get_thread_area(struct user_desc __user *user_desc)
+{
+	struct user_desc info;
+	int idx, ret;
+
+	if (get_user(idx, &user_desc->entry_number))
+		return -EFAULT;
+
+	ret = get_tls_entry(current, &info, idx);
+	if (ret < 0)
+		goto out;
+
+	if (copy_to_user(user_desc, &info, sizeof(info)))
+		ret = -EFAULT;
+
+out:
+	return ret;
+}
+
+/*
+ * Perform get_thread_area on behalf of the traced child.
+ */
+int ptrace_get_thread_area(struct task_struct *child, int idx,
+		struct user_desc __user *user_desc)
+{
+	struct user_desc info;
+	int ret;
+
+	ret = get_tls_entry(child, &info, idx);
+	if (ret < 0)
+		goto out;
+
+	if (copy_to_user(user_desc, &info, sizeof(info)))
+		ret = -EFAULT;
+out:
+	return ret;
+}
diff --git a/arch/um/sys-x86_64/Makefile b/arch/um/sys-x86_64/Makefile
index 1ee2ed1..b5fc22b 100644
--- a/arch/um/sys-x86_64/Makefile
+++ b/arch/um/sys-x86_64/Makefile
@@ -5,7 +5,8 @@
 #
 
 obj-y = bugs.o delay.o fault.o ldt.o mem.o ptrace.o ptrace_user.o \
-	sigcontext.o signal.o syscalls.o syscall_table.o sysrq.o ksyms.o
+	sigcontext.o signal.o syscalls.o syscall_table.o sysrq.o ksyms.o \
+	tls.o
 
 obj-$(CONFIG_MODE_SKAS) += stub.o stub_segv.o
 obj-$(CONFIG_MODULES) += um_module.o
diff --git a/arch/um/sys-x86_64/tls.c b/arch/um/sys-x86_64/tls.c
new file mode 100644
index 0000000..ce1bf1b
--- /dev/null
+++ b/arch/um/sys-x86_64/tls.c
@@ -0,0 +1,14 @@
+#include "linux/sched.h"
+
+void debug_arch_force_load_TLS(void)
+{
+}
+
+void clear_flushed_tls(struct task_struct *task)
+{
+}
+
+int arch_copy_tls(struct task_struct *t)
+{
+        return 0;
+}