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;
+}