aboutsummaryrefslogtreecommitdiffstats
path: root/os/kernel/include/chmtx.h
blob: 95ffb72e446d67712c1787c17d0924161bb06e6b (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
/*
    ChibiOS/RT - Copyright (C) 2006,2007,2008,2009,2010,
                 2011,2012 Giovanni Di Sirio.

    This file is part of ChibiOS/RT.

    ChibiOS/RT is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 3 of the License, or
    (at your option) any later version.

    ChibiOS/RT is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

/**
 * @file    chmtx.h
 * @brief   Mutexes macros and structures.
 *
 * @addtogroup mutexes
 * @{
 */

#ifndef _CHMTX_H_
#define _CHMTX_H_

#if CH_USE_MUTEXES || defined(__DOXYGEN__)

/**
 * @brief   Mutex structure.
 */
typedef struct Mutex {
  ThreadsQueue          m_queue;    /**< @brief Queue of the threads sleeping
                                                on this Mutex.              */
  Thread                *m_owner;   /**< @brief Owner @p Thread pointer or
                                                @p NULL.                    */
  struct Mutex          *m_next;    /**< @brief Next @p Mutex into an
                                                owner-list or @p NULL.      */
} Mutex;

#ifdef __cplusplus
extern "C" {
#endif
  void chMtxInit(Mutex *mp);
  void chMtxLock(Mutex *mp);
  void chMtxLockS(Mutex *mp);
  bool_t chMtxTryLock(Mutex *mp);
  bool_t chMtxTryLockS(Mutex *mp);
  Mutex *chMtxUnlock(void);
  Mutex *chMtxUnlockS(void);
  void chMtxUnlockAll(void);
#ifdef __cplusplus
}
#endif

/**
 * @brief   Data part of a static mutex initializer.
 * @details This macro should be used when statically initializing a mutex
 *          that is part of a bigger structure.
 *
 * @param[in] name      the name of the mutex variable
 */
#define _MUTEX_DATA(name) {_THREADSQUEUE_DATA(name.m_queue), NULL, NULL}

/**
 * @brief   Static mutex initializer.
 * @details Statically initialized mutexes require no explicit initialization
 *          using @p chMtxInit().
 *
 * @param[in] name      the name of the mutex variable
 */
#define MUTEX_DECL(name) Mutex name = _MUTEX_DATA(name)

/**
 * @name    Macro Functions
 * @{
 */
/**
 * @brief   Returns @p TRUE if the mutex queue contains at least a waiting
 *          thread.
 *
 * @sclass
 */
#define chMtxQueueNotEmptyS(mp) notempty(&(mp)->m_queue)
/** @} */

#endif /* CH_USE_MUTEXES */

#endif /* _CHMTX_H_ */

/** @} */
id='n413' href='#n413'>413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792
/*
 *  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/cpu.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>
#include <asm-xen/xen-public/physdev.h>
#ifdef CONFIG_MATH_EMULATION
#include <asm/math_emu.h>
#endif

#include <linux/irq.h>
#include <linux/err.h>

#include <asm/tlbflush.h>
#include <asm/cpu.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);

/* XXX XEN doesn't use default_idle(), poll_idle(). Use xen_idle() instead. */
extern void stop_hz_timer(void);
extern void start_hz_timer(void);
void xen_idle(void)
{
	local_irq_disable();

	if (need_resched()) {
		local_irq_enable();
	} else {
		stop_hz_timer();
		HYPERVISOR_block(); /* implicit local_irq_enable() */
		start_hz_timer();
	}
}

#ifdef CONFIG_HOTPLUG_CPU
#include <asm/nmi.h>
/* We don't actually take CPU down, just spin without interrupts. */
static inline void play_dead(void)
{
	/* Death loop */
	while (__get_cpu_var(cpu_state) != CPU_UP_PREPARE)
		HYPERVISOR_yield();

	__flush_tlb_all();
	cpu_set(smp_processor_id(), cpu_online_map);
}
#else
static inline void play_dead(void)
{
	BUG();
}
#endif /* CONFIG_HOTPLUG_CPU */

/*
 * 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)
{
	int cpu = _smp_processor_id();

	/* endless idle loop with no priority at all */
	while (1) {
		while (!need_resched()) {

			if (__get_cpu_var(cpu_idle_state))
				__get_cpu_var(cpu_idle_state) = 0;
			rmb();

			if (cpu_is_offline(cpu)) {
				local_irq_disable();
				/* Ack it.  From this point on until
				   we get woken up, we're not allowed
				   to take any locks.  In particular,
				   don't printk. */
				__get_cpu_var(cpu_state) = CPU_DEAD;
#if defined(CONFIG_XEN) && defined(CONFIG_HOTPLUG_CPU)
				/* Tell hypervisor to take vcpu down. */
				HYPERVISOR_vcpu_down(cpu);
#endif
				play_dead();
				local_irq_enable();
			}

			__get_cpu_var(irq_stat).idle_timestamp = jiffies;
			xen_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);

/* XXX XEN doesn't use mwait_idle(), select_idle_routine(), idle_setup(). */
/* Always use xen_idle() instead. */
void __init select_idle_routine(const struct cpuinfo_x86 *c) {}

void show_regs(struct pt_regs * regs)
{
	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 & 2)
		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);

	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)) {
		physdev_op_t op = { 0 };
		op.cmd = PHYSDEVOP_SET_IOBITMAP;
		HYPERVISOR_physdev_op(&op);
		kfree(t->io_bitmap_ptr);
		t->io_bitmap_ptr = NULL;
	}
}

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;
	/*
	 * The below -8 is to reserve 8 bytes on top of the ring0 stack.
	 * This is necessary to guarantee that the entire "struct pt_regs"
	 * is accessable even if the CPU haven't stored the SS/ESP registers
	 * on the stack (interrupt gate does not save these registers
	 * when switching to the same priv ring).
	 * Therefore beware: accessing the xss/esp fields of the
	 * "struct pt_regs" is possible, but they may contain the
	 * completely wrong values.
	 */
	childregs = (struct pt_regs *) ((unsigned long) childregs - 8);
	*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);
	}

	p->thread.io_pl = current->thread.io_pl;

	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);

	boot_option_idle_override = 1;
	return 1;
}


/*
 *	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);
	physdev_op_t iopl_op, iobmp_op;
	multicall_entry_t _mcl[8], *mcl = _mcl;

	/* XEN NOTE: FS/GS saved in switch_mm(), not here. */

	/*
	 * This is basically '__unlazy_fpu', except that we queue a
	 * multicall to indicate FPU task switch, rather than
	 * synchronously trapping to Xen.
	 */
	if (prev_p->thread_info->status & TS_USEDFPU) {
		__save_init_fpu(prev_p); /* _not_ save_init_fpu() */
		mcl->op      = __HYPERVISOR_fpu_taskswitch;
		mcl->args[0] = 1;
		mcl++;
	}

	/*
	 * Reload esp0, LDT and the page table pointer:
	 * This is load_esp0(tss, next) with a multicall.
	 */
	tss->esp0 = next->esp0;
	mcl->op      = __HYPERVISOR_stack_switch;
	mcl->args[0] = tss->ss0;
	mcl->args[1] = tss->esp0;
	mcl++;

	/*
	 * Load the per-thread Thread-Local Storage descriptor.
	 * This is load_TLS(next, cpu) with multicalls.
	 */
#define C(i) do {                                                       \
	if (unlikely(next->tls_array[i].a != prev->tls_array[i].a ||    \
		     next->tls_array[i].b != prev->tls_array[i].b)) {   \
		mcl->op      = __HYPERVISOR_update_descriptor;          \
		mcl->args[0] = virt_to_machine(&get_cpu_gdt_table(cpu)  \
					 [GDT_ENTRY_TLS_MIN + i]);      \
		mcl->args[1] = ((u32 *)&next->tls_array[i])[0];         \
		mcl->args[2] = ((u32 *)&next->tls_array[i])[1];         \
		mcl++;                                                  \
	}                                                               \
} while (0)
	C(0); C(1); C(2);
#undef C

	if (unlikely(prev->io_pl != next->io_pl)) {
		iopl_op.cmd             = PHYSDEVOP_SET_IOPL;
		iopl_op.u.set_iopl.iopl = (next->io_pl == 0) ? 1 : next->io_pl;
		mcl->op      = __HYPERVISOR_physdev_op;
		mcl->args[0] = (unsigned long)&iopl_op;
		mcl++;
	}

	if (unlikely(prev->io_bitmap_ptr || next->io_bitmap_ptr)) {
		iobmp_op.cmd                     =
			PHYSDEVOP_SET_IOBITMAP;
		iobmp_op.u.set_iobitmap.bitmap   =
			(unsigned long)next->io_bitmap_ptr;
		iobmp_op.u.set_iobitmap.nr_ports =
			next->io_bitmap_ptr ? IO_BITMAP_BITS : 0;
		mcl->op      = __HYPERVISOR_physdev_op;
		mcl->args[0] = (unsigned long)&iobmp_op;
		mcl++;
	}

	(void)HYPERVISOR_multicall(_mcl, mcl - _mcl);

	/*
	 * Restore %fs and %gs if needed.
	 */
	if (unlikely(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);
	}

	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;
}