Linux-2.6.12-rc2v2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!

1 files changed, 848 insertions, 0 deletions

diff --git a/arch/i386/kernel/process.c b/arch/i386/kernel/process.c
new file mode 100644
index 000000000000..c36fedf40e95
--- /dev/null
+++ b/arch/i386/kernel/process.c
@@ -0,0 +1,848 @@
+/*
+ *  linux/arch/i386/kernel/process.c
+ *
+ *  Copyright (C) 1995  Linus Torvalds
+ *
+ *  Pentium III FXSR, SSE support
+ *	Gareth Hughes <gareth@valinux.com>, May 2000
+ */
+
+/*
+ * This file handles the architecture-dependent parts of process handling..
+ */
+
+#include <stdarg.h>
+
+#include <linux/errno.h>
+#include <linux/sched.h>
+#include <linux/fs.h>
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/elfcore.h>
+#include <linux/smp.h>
+#include <linux/smp_lock.h>
+#include <linux/stddef.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+#include <linux/user.h>
+#include <linux/a.out.h>
+#include <linux/interrupt.h>
+#include <linux/config.h>
+#include <linux/utsname.h>
+#include <linux/delay.h>
+#include <linux/reboot.h>
+#include <linux/init.h>
+#include <linux/mc146818rtc.h>
+#include <linux/module.h>
+#include <linux/kallsyms.h>
+#include <linux/ptrace.h>
+#include <linux/random.h>
+
+#include <asm/uaccess.h>
+#include <asm/pgtable.h>
+#include <asm/system.h>
+#include <asm/io.h>
+#include <asm/ldt.h>
+#include <asm/processor.h>
+#include <asm/i387.h>
+#include <asm/irq.h>
+#include <asm/desc.h>
+#ifdef CONFIG_MATH_EMULATION
+#include <asm/math_emu.h>
+#endif
+
+#include <linux/irq.h>
+#include <linux/err.h>
+
+asmlinkage void ret_from_fork(void) __asm__("ret_from_fork");
+
+static int hlt_counter;
+
+unsigned long boot_option_idle_override = 0;
+EXPORT_SYMBOL(boot_option_idle_override);
+
+/*
+ * Return saved PC of a blocked thread.
+ */
+unsigned long thread_saved_pc(struct task_struct *tsk)
+{
+	return ((unsigned long *)tsk->thread.esp)[3];
+}
+
+/*
+ * Powermanagement idle function, if any..
+ */
+void (*pm_idle)(void);
+static DEFINE_PER_CPU(unsigned int, cpu_idle_state);
+
+void disable_hlt(void)
+{
+	hlt_counter++;
+}
+
+EXPORT_SYMBOL(disable_hlt);
+
+void enable_hlt(void)
+{
+	hlt_counter--;
+}
+
+EXPORT_SYMBOL(enable_hlt);
+
+/*
+ * We use this if we don't have any better
+ * idle routine..
+ */
+void default_idle(void)
+{
+	if (!hlt_counter && boot_cpu_data.hlt_works_ok) {
+		local_irq_disable();
+		if (!need_resched())
+			safe_halt();
+		else
+			local_irq_enable();
+	} else {
+		cpu_relax();
+	}
+}
+
+/*
+ * On SMP it's slightly faster (but much more power-consuming!)
+ * to poll the ->work.need_resched flag instead of waiting for the
+ * cross-CPU IPI to arrive. Use this option with caution.
+ */
+static void poll_idle (void)
+{
+	int oldval;
+
+	local_irq_enable();
+
+	/*
+	 * Deal with another CPU just having chosen a thread to
+	 * run here:
+	 */
+	oldval = test_and_clear_thread_flag(TIF_NEED_RESCHED);
+
+	if (!oldval) {
+		set_thread_flag(TIF_POLLING_NRFLAG);
+		asm volatile(
+			"2:"
+			"testl %0, %1;"
+			"rep; nop;"
+			"je 2b;"
+			: : "i"(_TIF_NEED_RESCHED), "m" (current_thread_info()->flags));
+
+		clear_thread_flag(TIF_POLLING_NRFLAG);
+	} else {
+		set_need_resched();
+	}
+}
+
+/*
+ * The idle thread. There's no useful work to be
+ * done, so just try to conserve power and have a
+ * low exit latency (ie sit in a loop waiting for
+ * somebody to say that they'd like to reschedule)
+ */
+void cpu_idle (void)
+{
+	/* endless idle loop with no priority at all */
+	while (1) {
+		while (!need_resched()) {
+			void (*idle)(void);
+
+			if (__get_cpu_var(cpu_idle_state))
+				__get_cpu_var(cpu_idle_state) = 0;
+
+			rmb();
+			idle = pm_idle;
+
+			if (!idle)
+				idle = default_idle;
+
+			__get_cpu_var(irq_stat).idle_timestamp = jiffies;
+			idle();
+		}
+		schedule();
+	}
+}
+
+void cpu_idle_wait(void)
+{
+	unsigned int cpu, this_cpu = get_cpu();
+	cpumask_t map;
+
+	set_cpus_allowed(current, cpumask_of_cpu(this_cpu));
+	put_cpu();
+
+	cpus_clear(map);
+	for_each_online_cpu(cpu) {
+		per_cpu(cpu_idle_state, cpu) = 1;
+		cpu_set(cpu, map);
+	}
+
+	__get_cpu_var(cpu_idle_state) = 0;
+
+	wmb();
+	do {
+		ssleep(1);
+		for_each_online_cpu(cpu) {
+			if (cpu_isset(cpu, map) && !per_cpu(cpu_idle_state, cpu))
+				cpu_clear(cpu, map);
+		}
+		cpus_and(map, map, cpu_online_map);
+	} while (!cpus_empty(map));
+}
+EXPORT_SYMBOL_GPL(cpu_idle_wait);
+
+/*
+ * This uses new MONITOR/MWAIT instructions on P4 processors with PNI,
+ * which can obviate IPI to trigger checking of need_resched.
+ * We execute MONITOR against need_resched and enter optimized wait state
+ * through MWAIT. Whenever someone changes need_resched, we would be woken
+ * up from MWAIT (without an IPI).
+ */
+static void mwait_idle(void)
+{
+	local_irq_enable();
+
+	if (!need_resched()) {
+		set_thread_flag(TIF_POLLING_NRFLAG);
+		do {
+			__monitor((void *)&current_thread_info()->flags, 0, 0);
+			if (need_resched())
+				break;
+			__mwait(0, 0);
+		} while (!need_resched());
+		clear_thread_flag(TIF_POLLING_NRFLAG);
+	}
+}
+
+void __init select_idle_routine(const struct cpuinfo_x86 *c)
+{
+	if (cpu_has(c, X86_FEATURE_MWAIT)) {
+		printk("monitor/mwait feature present.\n");
+		/*
+		 * Skip, if setup has overridden idle.
+		 * One CPU supports mwait => All CPUs supports mwait
+		 */
+		if (!pm_idle) {
+			printk("using mwait in idle threads.\n");
+			pm_idle = mwait_idle;
+		}
+	}
+}
+
+static int __init idle_setup (char *str)
+{
+	if (!strncmp(str, "poll", 4)) {
+		printk("using polling idle threads.\n");
+		pm_idle = poll_idle;
+#ifdef CONFIG_X86_SMP
+		if (smp_num_siblings > 1)
+			printk("WARNING: polling idle and HT enabled, performance may degrade.\n");
+#endif
+	} else if (!strncmp(str, "halt", 4)) {
+		printk("using halt in idle threads.\n");
+		pm_idle = default_idle;
+	}
+
+	boot_option_idle_override = 1;
+	return 1;
+}
+
+__setup("idle=", idle_setup);
+
+void show_regs(struct pt_regs * regs)
+{
+	unsigned long cr0 = 0L, cr2 = 0L, cr3 = 0L, cr4 = 0L;
+
+	printk("\n");
+	printk("Pid: %d, comm: %20s\n", current->pid, current->comm);
+	printk("EIP: %04x:[<%08lx>] CPU: %d\n",0xffff & regs->xcs,regs->eip, smp_processor_id());
+	print_symbol("EIP is at %s\n", regs->eip);
+
+	if (regs->xcs & 3)
+		printk(" ESP: %04x:%08lx",0xffff & regs->xss,regs->esp);
+	printk(" EFLAGS: %08lx    %s  (%s)\n",
+	       regs->eflags, print_tainted(), system_utsname.release);
+	printk("EAX: %08lx EBX: %08lx ECX: %08lx EDX: %08lx\n",
+		regs->eax,regs->ebx,regs->ecx,regs->edx);
+	printk("ESI: %08lx EDI: %08lx EBP: %08lx",
+		regs->esi, regs->edi, regs->ebp);
+	printk(" DS: %04x ES: %04x\n",
+		0xffff & regs->xds,0xffff & regs->xes);
+
+	__asm__("movl %%cr0, %0": "=r" (cr0));
+	__asm__("movl %%cr2, %0": "=r" (cr2));
+	__asm__("movl %%cr3, %0": "=r" (cr3));
+	/* This could fault if %cr4 does not exist */
+	__asm__("1: movl %%cr4, %0		\n"
+		"2:				\n"
+		".section __ex_table,\"a\"	\n"
+		".long 1b,2b			\n"
+		".previous			\n"
+		: "=r" (cr4): "0" (0));
+	printk("CR0: %08lx CR2: %08lx CR3: %08lx CR4: %08lx\n", cr0, cr2, cr3, cr4);
+	show_trace(NULL, &regs->esp);
+}
+
+/*
+ * This gets run with %ebx containing the
+ * function to call, and %edx containing
+ * the "args".
+ */
+extern void kernel_thread_helper(void);
+__asm__(".section .text\n"
+	".align 4\n"
+	"kernel_thread_helper:\n\t"
+	"movl %edx,%eax\n\t"
+	"pushl %edx\n\t"
+	"call *%ebx\n\t"
+	"pushl %eax\n\t"
+	"call do_exit\n"
+	".previous");
+
+/*
+ * Create a kernel thread
+ */
+int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
+{
+	struct pt_regs regs;
+
+	memset(&regs, 0, sizeof(regs));
+
+	regs.ebx = (unsigned long) fn;
+	regs.edx = (unsigned long) arg;
+
+	regs.xds = __USER_DS;
+	regs.xes = __USER_DS;
+	regs.orig_eax = -1;
+	regs.eip = (unsigned long) kernel_thread_helper;
+	regs.xcs = __KERNEL_CS;
+	regs.eflags = X86_EFLAGS_IF | X86_EFLAGS_SF | X86_EFLAGS_PF | 0x2;
+
+	/* Ok, create the new process.. */
+	return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, &regs, 0, NULL, NULL);
+}
+
+/*
+ * Free current thread data structures etc..
+ */
+void exit_thread(void)
+{
+	struct task_struct *tsk = current;
+	struct thread_struct *t = &tsk->thread;
+
+	/* The process may have allocated an io port bitmap... nuke it. */
+	if (unlikely(NULL != t->io_bitmap_ptr)) {
+		int cpu = get_cpu();
+		struct tss_struct *tss = &per_cpu(init_tss, cpu);
+
+		kfree(t->io_bitmap_ptr);
+		t->io_bitmap_ptr = NULL;
+		/*
+		 * Careful, clear this in the TSS too:
+		 */
+		memset(tss->io_bitmap, 0xff, tss->io_bitmap_max);
+		t->io_bitmap_max = 0;
+		tss->io_bitmap_owner = NULL;
+		tss->io_bitmap_max = 0;
+		tss->io_bitmap_base = INVALID_IO_BITMAP_OFFSET;
+		put_cpu();
+	}
+}
+
+void flush_thread(void)
+{
+	struct task_struct *tsk = current;
+
+	memset(tsk->thread.debugreg, 0, sizeof(unsigned long)*8);
+	memset(tsk->thread.tls_array, 0, sizeof(tsk->thread.tls_array));	
+	/*
+	 * Forget coprocessor state..
+	 */
+	clear_fpu(tsk);
+	clear_used_math();
+}
+
+void release_thread(struct task_struct *dead_task)
+{
+	if (dead_task->mm) {
+		// temporary debugging check
+		if (dead_task->mm->context.size) {
+			printk("WARNING: dead process %8s still has LDT? <%p/%d>\n",
+					dead_task->comm,
+					dead_task->mm->context.ldt,
+					dead_task->mm->context.size);
+			BUG();
+		}
+	}
+
+	release_vm86_irqs(dead_task);
+}
+
+/*
+ * This gets called before we allocate a new thread and copy
+ * the current task into it.
+ */
+void prepare_to_copy(struct task_struct *tsk)
+{
+	unlazy_fpu(tsk);
+}
+
+int copy_thread(int nr, unsigned long clone_flags, unsigned long esp,
+	unsigned long unused,
+	struct task_struct * p, struct pt_regs * regs)
+{
+	struct pt_regs * childregs;
+	struct task_struct *tsk;
+	int err;
+
+	childregs = ((struct pt_regs *) (THREAD_SIZE + (unsigned long) p->thread_info)) - 1;
+	*childregs = *regs;
+	childregs->eax = 0;
+	childregs->esp = esp;
+
+	p->thread.esp = (unsigned long) childregs;
+	p->thread.esp0 = (unsigned long) (childregs+1);
+
+	p->thread.eip = (unsigned long) ret_from_fork;
+
+	savesegment(fs,p->thread.fs);
+	savesegment(gs,p->thread.gs);
+
+	tsk = current;
+	if (unlikely(NULL != tsk->thread.io_bitmap_ptr)) {
+		p->thread.io_bitmap_ptr = kmalloc(IO_BITMAP_BYTES, GFP_KERNEL);
+		if (!p->thread.io_bitmap_ptr) {
+			p->thread.io_bitmap_max = 0;
+			return -ENOMEM;
+		}
+		memcpy(p->thread.io_bitmap_ptr, tsk->thread.io_bitmap_ptr,
+			IO_BITMAP_BYTES);
+	}
+
+	/*
+	 * Set a new TLS for the child thread?
+	 */
+	if (clone_flags & CLONE_SETTLS) {
+		struct desc_struct *desc;
+		struct user_desc info;
+		int idx;
+
+		err = -EFAULT;
+		if (copy_from_user(&info, (void __user *)childregs->esi, sizeof(info)))
+			goto out;
+		err = -EINVAL;
+		if (LDT_empty(&info))
+			goto out;
+
+		idx = info.entry_number;
+		if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX)
+			goto out;
+
+		desc = p->thread.tls_array + idx - GDT_ENTRY_TLS_MIN;
+		desc->a = LDT_entry_a(&info);
+		desc->b = LDT_entry_b(&info);
+	}
+
+	err = 0;
+ out:
+	if (err && p->thread.io_bitmap_ptr) {
+		kfree(p->thread.io_bitmap_ptr);
+		p->thread.io_bitmap_max = 0;
+	}
+	return err;
+}
+
+/*
+ * fill in the user structure for a core dump..
+ */
+void dump_thread(struct pt_regs * regs, struct user * dump)
+{
+	int i;
+
+/* changed the size calculations - should hopefully work better. lbt */
+	dump->magic = CMAGIC;
+	dump->start_code = 0;
+	dump->start_stack = regs->esp & ~(PAGE_SIZE - 1);
+	dump->u_tsize = ((unsigned long) current->mm->end_code) >> PAGE_SHIFT;
+	dump->u_dsize = ((unsigned long) (current->mm->brk + (PAGE_SIZE-1))) >> PAGE_SHIFT;
+	dump->u_dsize -= dump->u_tsize;
+	dump->u_ssize = 0;
+	for (i = 0; i < 8; i++)
+		dump->u_debugreg[i] = current->thread.debugreg[i];  
+
+	if (dump->start_stack < TASK_SIZE)
+		dump->u_ssize = ((unsigned long) (TASK_SIZE - dump->start_stack)) >> PAGE_SHIFT;
+
+	dump->regs.ebx = regs->ebx;
+	dump->regs.ecx = regs->ecx;
+	dump->regs.edx = regs->edx;
+	dump->regs.esi = regs->esi;
+	dump->regs.edi = regs->edi;
+	dump->regs.ebp = regs->ebp;
+	dump->regs.eax = regs->eax;
+	dump->regs.ds = regs->xds;
+	dump->regs.es = regs->xes;
+	savesegment(fs,dump->regs.fs);
+	savesegment(gs,dump->regs.gs);
+	dump->regs.orig_eax = regs->orig_eax;
+	dump->regs.eip = regs->eip;
+	dump->regs.cs = regs->xcs;
+	dump->regs.eflags = regs->eflags;
+	dump->regs.esp = regs->esp;
+	dump->regs.ss = regs->xss;
+
+	dump->u_fpvalid = dump_fpu (regs, &dump->i387);
+}
+
+/* 
+ * Capture the user space registers if the task is not running (in user space)
+ */
+int dump_task_regs(struct task_struct *tsk, elf_gregset_t *regs)
+{
+	struct pt_regs ptregs;
+	
+	ptregs = *(struct pt_regs *)
+		((unsigned long)tsk->thread_info+THREAD_SIZE - sizeof(ptregs));
+	ptregs.xcs &= 0xffff;
+	ptregs.xds &= 0xffff;
+	ptregs.xes &= 0xffff;
+	ptregs.xss &= 0xffff;
+
+	elf_core_copy_regs(regs, &ptregs);
+
+	return 1;
+}
+
+static inline void
+handle_io_bitmap(struct thread_struct *next, struct tss_struct *tss)
+{
+	if (!next->io_bitmap_ptr) {
+		/*
+		 * Disable the bitmap via an invalid offset. We still cache
+		 * the previous bitmap owner and the IO bitmap contents:
+		 */
+		tss->io_bitmap_base = INVALID_IO_BITMAP_OFFSET;
+		return;
+	}
+	if (likely(next == tss->io_bitmap_owner)) {
+		/*
+		 * Previous owner of the bitmap (hence the bitmap content)
+		 * matches the next task, we dont have to do anything but
+		 * to set a valid offset in the TSS:
+		 */
+		tss->io_bitmap_base = IO_BITMAP_OFFSET;
+		return;
+	}
+	/*
+	 * Lazy TSS's I/O bitmap copy. We set an invalid offset here
+	 * and we let the task to get a GPF in case an I/O instruction
+	 * is performed.  The handler of the GPF will verify that the
+	 * faulting task has a valid I/O bitmap and, it true, does the
+	 * real copy and restart the instruction.  This will save us
+	 * redundant copies when the currently switched task does not
+	 * perform any I/O during its timeslice.
+	 */
+	tss->io_bitmap_base = INVALID_IO_BITMAP_OFFSET_LAZY;
+}
+/*
+ * This special macro can be used to load a debugging register
+ */
+#define loaddebug(thread,register) \
+		__asm__("movl %0,%%db" #register  \
+			: /* no output */ \
+			:"r" (thread->debugreg[register]))
+
+/*
+ *	switch_to(x,yn) should switch tasks from x to y.
+ *
+ * We fsave/fwait so that an exception goes off at the right time
+ * (as a call from the fsave or fwait in effect) rather than to
+ * the wrong process. Lazy FP saving no longer makes any sense
+ * with modern CPU's, and this simplifies a lot of things (SMP
+ * and UP become the same).
+ *
+ * NOTE! We used to use the x86 hardware context switching. The
+ * reason for not using it any more becomes apparent when you
+ * try to recover gracefully from saved state that is no longer
+ * valid (stale segment register values in particular). With the
+ * hardware task-switch, there is no way to fix up bad state in
+ * a reasonable manner.
+ *
+ * The fact that Intel documents the hardware task-switching to
+ * be slow is a fairly red herring - this code is not noticeably
+ * faster. However, there _is_ some room for improvement here,
+ * so the performance issues may eventually be a valid point.
+ * More important, however, is the fact that this allows us much
+ * more flexibility.
+ *
+ * The return value (in %eax) will be the "prev" task after
+ * the task-switch, and shows up in ret_from_fork in entry.S,
+ * for example.
+ */
+struct task_struct fastcall * __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
+{
+	struct thread_struct *prev = &prev_p->thread,
+				 *next = &next_p->thread;
+	int cpu = smp_processor_id();
+	struct tss_struct *tss = &per_cpu(init_tss, cpu);
+
+	/* never put a printk in __switch_to... printk() calls wake_up*() indirectly */
+
+	__unlazy_fpu(prev_p);
+
+	/*
+	 * Reload esp0, LDT and the page table pointer:
+	 */
+	load_esp0(tss, next);
+
+	/*
+	 * Load the per-thread Thread-Local Storage descriptor.
+	 */
+	load_TLS(next, cpu);
+
+	/*
+	 * Save away %fs and %gs. No need to save %es and %ds, as
+	 * those are always kernel segments while inside the kernel.
+	 */
+	asm volatile("movl %%fs,%0":"=m" (*(int *)&prev->fs));
+	asm volatile("movl %%gs,%0":"=m" (*(int *)&prev->gs));
+
+	/*
+	 * Restore %fs and %gs if needed.
+	 */
+	if (unlikely(prev->fs | prev->gs | next->fs | next->gs)) {
+		loadsegment(fs, next->fs);
+		loadsegment(gs, next->gs);
+	}
+
+	/*
+	 * Now maybe reload the debug registers
+	 */
+	if (unlikely(next->debugreg[7])) {
+		loaddebug(next, 0);
+		loaddebug(next, 1);
+		loaddebug(next, 2);
+		loaddebug(next, 3);
+		/* no 4 and 5 */
+		loaddebug(next, 6);
+		loaddebug(next, 7);
+	}
+
+	if (unlikely(prev->io_bitmap_ptr || next->io_bitmap_ptr))
+		handle_io_bitmap(next, tss);
+
+	return prev_p;
+}
+
+asmlinkage int sys_fork(struct pt_regs regs)
+{
+	return do_fork(SIGCHLD, regs.esp, &regs, 0, NULL, NULL);
+}
+
+asmlinkage int sys_clone(struct pt_regs regs)
+{
+	unsigned long clone_flags;
+	unsigned long newsp;
+	int __user *parent_tidptr, *child_tidptr;
+
+	clone_flags = regs.ebx;
+	newsp = regs.ecx;
+	parent_tidptr = (int __user *)regs.edx;
+	child_tidptr = (int __user *)regs.edi;
+	if (!newsp)
+		newsp = regs.esp;
+	return do_fork(clone_flags, newsp, &regs, 0, parent_tidptr, child_tidptr);
+}
+
+/*
+ * This is trivial, and on the face of it looks like it
+ * could equally well be done in user mode.
+ *
+ * Not so, for quite unobvious reasons - register pressure.
+ * In user mode vfork() cannot have a stack frame, and if
+ * done by calling the "clone()" system call directly, you
+ * do not have enough call-clobbered registers to hold all
+ * the information you need.
+ */
+asmlinkage int sys_vfork(struct pt_regs regs)
+{
+	return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, regs.esp, &regs, 0, NULL, NULL);
+}
+
+/*
+ * sys_execve() executes a new program.
+ */
+asmlinkage int sys_execve(struct pt_regs regs)
+{
+	int error;
+	char * filename;
+
+	filename = getname((char __user *) regs.ebx);
+	error = PTR_ERR(filename);
+	if (IS_ERR(filename))
+		goto out;
+	error = do_execve(filename,
+			(char __user * __user *) regs.ecx,
+			(char __user * __user *) regs.edx,
+			&regs);
+	if (error == 0) {
+		task_lock(current);
+		current->ptrace &= ~PT_DTRACE;
+		task_unlock(current);
+		/* Make sure we don't return using sysenter.. */
+		set_thread_flag(TIF_IRET);
+	}
+	putname(filename);
+out:
+	return error;
+}
+
+#define top_esp                (THREAD_SIZE - sizeof(unsigned long))
+#define top_ebp                (THREAD_SIZE - 2*sizeof(unsigned long))
+
+unsigned long get_wchan(struct task_struct *p)
+{
+	unsigned long ebp, esp, eip;
+	unsigned long stack_page;
+	int count = 0;
+	if (!p || p == current || p->state == TASK_RUNNING)
+		return 0;
+	stack_page = (unsigned long)p->thread_info;
+	esp = p->thread.esp;
+	if (!stack_page || esp < stack_page || esp > top_esp+stack_page)
+		return 0;
+	/* include/asm-i386/system.h:switch_to() pushes ebp last. */
+	ebp = *(unsigned long *) esp;
+	do {
+		if (ebp < stack_page || ebp > top_ebp+stack_page)
+			return 0;
+		eip = *(unsigned long *) (ebp+4);
+		if (!in_sched_functions(eip))
+			return eip;
+		ebp = *(unsigned long *) ebp;
+	} while (count++ < 16);
+	return 0;
+}
+
+/*
+ * 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;
+}
+
+/*
+ * Set a given TLS descriptor:
+ */
+asmlinkage int sys_set_thread_area(struct user_desc __user *u_info)
+{
+	struct thread_struct *t = &current->thread;
+	struct user_desc info;
+	struct 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 = 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);
+	}
+	load_TLS(t, cpu);
+
+	put_cpu();
+
+	return 0;
+}
+
+/*
+ * Get the current Thread-Local Storage area:
+ */
+
+#define GET_BASE(desc) ( \
+	(((desc)->a >> 16) & 0x0000ffff) | \
+	(((desc)->b << 16) & 0x00ff0000) | \
+	( (desc)->b        & 0xff000000)   )
+
+#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)
+
+asmlinkage int sys_get_thread_area(struct user_desc __user *u_info)
+{
+	struct user_desc info;
+	struct 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 = current->thread.tls_array + idx - GDT_ENTRY_TLS_MIN;
+
+	info.entry_number = idx;
+	info.base_addr = GET_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);
+
+	if (copy_to_user(u_info, &info, sizeof(info)))
+		return -EFAULT;
+	return 0;
+}
+
+unsigned long arch_align_stack(unsigned long sp)
+{
+	if (randomize_va_space)
+		sp -= get_random_int() % 8192;
+	return sp & ~0xf;
+}