2 * Copyright (C) 1995 Linus Torvalds
4 * Pentium III FXSR, SSE support
5 * Gareth Hughes <gareth@valinux.com>, May 2000
9 * This file handles the architecture-dependent parts of process handling..
14 #include <linux/cpu.h>
15 #include <linux/errno.h>
16 #include <linux/sched.h>
18 #include <linux/kernel.h>
20 #include <linux/elfcore.h>
21 #include <linux/smp.h>
22 #include <linux/stddef.h>
23 #include <linux/slab.h>
24 #include <linux/vmalloc.h>
25 #include <linux/user.h>
26 #include <linux/a.out.h>
27 #include <linux/interrupt.h>
28 #include <linux/utsname.h>
29 #include <linux/delay.h>
30 #include <linux/reboot.h>
31 #include <linux/init.h>
32 #include <linux/mc146818rtc.h>
33 #include <linux/module.h>
34 #include <linux/kallsyms.h>
35 #include <linux/ptrace.h>
36 #include <linux/random.h>
37 #include <linux/personality.h>
38 #include <linux/tick.h>
39 #include <linux/percpu.h>
41 #include <asm/uaccess.h>
42 #include <asm/pgtable.h>
43 #include <asm/system.h>
46 #include <asm/processor.h>
50 #ifdef CONFIG_MATH_EMULATION
51 #include <asm/math_emu.h>
54 #include <linux/err.h>
56 #include <asm/tlbflush.h>
58 #include <asm/kdebug.h>
60 asmlinkage void ret_from_fork(void) __asm__("ret_from_fork");
62 static int hlt_counter;
64 unsigned long boot_option_idle_override = 0;
65 EXPORT_SYMBOL(boot_option_idle_override);
67 DEFINE_PER_CPU(struct task_struct *, current_task) = &init_task;
68 EXPORT_PER_CPU_SYMBOL(current_task);
70 DEFINE_PER_CPU(int, cpu_number);
71 EXPORT_PER_CPU_SYMBOL(cpu_number);
74 * Return saved PC of a blocked thread.
76 unsigned long thread_saved_pc(struct task_struct *tsk)
78 return ((unsigned long *)tsk->thread.esp)[3];
82 * Powermanagement idle function, if any..
84 void (*pm_idle)(void);
85 EXPORT_SYMBOL(pm_idle);
86 static DEFINE_PER_CPU(unsigned int, cpu_idle_state);
88 void disable_hlt(void)
93 EXPORT_SYMBOL(disable_hlt);
100 EXPORT_SYMBOL(enable_hlt);
103 * We use this if we don't have any better
106 void default_idle(void)
108 if (!hlt_counter && boot_cpu_data.hlt_works_ok) {
109 current_thread_info()->status &= ~TS_POLLING;
111 * TS_POLLING-cleared state must be visible before we
117 if (!need_resched()) {
122 t0n = ktime_to_ns(t0);
123 safe_halt(); /* enables interrupts racelessly */
126 t1n = ktime_to_ns(t1);
127 sched_clock_idle_wakeup_event(t1n - t0n);
130 current_thread_info()->status |= TS_POLLING;
132 /* loop is done by the caller */
136 #ifdef CONFIG_APM_MODULE
137 EXPORT_SYMBOL(default_idle);
141 * On SMP it's slightly faster (but much more power-consuming!)
142 * to poll the ->work.need_resched flag instead of waiting for the
143 * cross-CPU IPI to arrive. Use this option with caution.
145 static void poll_idle (void)
150 #ifdef CONFIG_HOTPLUG_CPU
152 /* We don't actually take CPU down, just spin without interrupts. */
153 static inline void play_dead(void)
155 /* This must be done before dead CPU ack */
160 __get_cpu_var(cpu_state) = CPU_DEAD;
163 * With physical CPU hotplug, we should halt the cpu
170 static inline void play_dead(void)
174 #endif /* CONFIG_HOTPLUG_CPU */
177 * The idle thread. There's no useful work to be
178 * done, so just try to conserve power and have a
179 * low exit latency (ie sit in a loop waiting for
180 * somebody to say that they'd like to reschedule)
184 int cpu = smp_processor_id();
186 current_thread_info()->status |= TS_POLLING;
188 /* endless idle loop with no priority at all */
190 tick_nohz_stop_sched_tick();
191 while (!need_resched()) {
194 if (__get_cpu_var(cpu_idle_state))
195 __get_cpu_var(cpu_idle_state) = 0;
204 if (cpu_is_offline(cpu))
207 __get_cpu_var(irq_stat).idle_timestamp = jiffies;
210 tick_nohz_restart_sched_tick();
211 preempt_enable_no_resched();
217 static void do_nothing(void *unused)
221 void cpu_idle_wait(void)
223 unsigned int cpu, this_cpu = get_cpu();
224 cpumask_t map, tmp = current->cpus_allowed;
226 set_cpus_allowed(current, cpumask_of_cpu(this_cpu));
230 for_each_online_cpu(cpu) {
231 per_cpu(cpu_idle_state, cpu) = 1;
235 __get_cpu_var(cpu_idle_state) = 0;
240 for_each_online_cpu(cpu) {
241 if (cpu_isset(cpu, map) && !per_cpu(cpu_idle_state, cpu))
244 cpus_and(map, map, cpu_online_map);
246 * We waited 1 sec, if a CPU still did not call idle
247 * it may be because it is in idle and not waking up
248 * because it has nothing to do.
249 * Give all the remaining CPUS a kick.
251 smp_call_function_mask(map, do_nothing, 0, 0);
252 } while (!cpus_empty(map));
254 set_cpus_allowed(current, tmp);
256 EXPORT_SYMBOL_GPL(cpu_idle_wait);
259 * This uses new MONITOR/MWAIT instructions on P4 processors with PNI,
260 * which can obviate IPI to trigger checking of need_resched.
261 * We execute MONITOR against need_resched and enter optimized wait state
262 * through MWAIT. Whenever someone changes need_resched, we would be woken
263 * up from MWAIT (without an IPI).
265 * New with Core Duo processors, MWAIT can take some hints based on CPU
268 void mwait_idle_with_hints(unsigned long eax, unsigned long ecx)
270 if (!need_resched()) {
271 __monitor((void *)¤t_thread_info()->flags, 0, 0);
278 /* Default MONITOR/MWAIT with no hints, used for default C1 state */
279 static void mwait_idle(void)
282 mwait_idle_with_hints(0, 0);
285 void __cpuinit select_idle_routine(const struct cpuinfo_x86 *c)
287 if (cpu_has(c, X86_FEATURE_MWAIT)) {
288 printk("monitor/mwait feature present.\n");
290 * Skip, if setup has overridden idle.
291 * One CPU supports mwait => All CPUs supports mwait
294 printk("using mwait in idle threads.\n");
295 pm_idle = mwait_idle;
300 static int __init idle_setup(char *str)
302 if (!strcmp(str, "poll")) {
303 printk("using polling idle threads.\n");
305 #ifdef CONFIG_X86_SMP
306 if (smp_num_siblings > 1)
307 printk("WARNING: polling idle and HT enabled, performance may degrade.\n");
309 } else if (!strcmp(str, "mwait"))
314 boot_option_idle_override = 1;
317 early_param("idle", idle_setup);
319 void __show_registers(struct pt_regs *regs, int all)
321 unsigned long cr0 = 0L, cr2 = 0L, cr3 = 0L, cr4 = 0L;
322 unsigned long d0, d1, d2, d3, d6, d7;
324 unsigned short ss, gs;
326 if (user_mode_vm(regs)) {
328 ss = regs->xss & 0xffff;
331 esp = (unsigned long) (®s->esp);
337 printk("Pid: %d, comm: %s %s (%s %.*s)\n",
338 task_pid_nr(current), current->comm,
339 print_tainted(), init_utsname()->release,
340 (int)strcspn(init_utsname()->version, " "),
341 init_utsname()->version);
343 printk("EIP: %04x:[<%08lx>] EFLAGS: %08lx CPU: %d\n",
344 0xffff & regs->xcs, regs->eip, regs->eflags,
346 print_symbol("EIP is at %s\n", regs->eip);
348 printk("EAX: %08lx EBX: %08lx ECX: %08lx EDX: %08lx\n",
349 regs->eax, regs->ebx, regs->ecx, regs->edx);
350 printk("ESI: %08lx EDI: %08lx EBP: %08lx ESP: %08lx\n",
351 regs->esi, regs->edi, regs->ebp, esp);
352 printk(" DS: %04x ES: %04x FS: %04x GS: %04x SS: %04x\n",
353 regs->xds & 0xffff, regs->xes & 0xffff,
354 regs->xfs & 0xffff, gs, ss);
362 cr4 = read_cr4_safe();
363 printk("CR0: %08lx CR2: %08lx CR3: %08lx CR4: %08lx\n",
370 printk("DR0: %08lx DR1: %08lx DR2: %08lx DR3: %08lx\n",
375 printk("DR6: %08lx DR7: %08lx\n",
379 void show_regs(struct pt_regs *regs)
381 __show_registers(regs, 1);
382 show_trace(NULL, regs, ®s->esp);
386 * This gets run with %ebx containing the
387 * function to call, and %edx containing
390 extern void kernel_thread_helper(void);
393 * Create a kernel thread
395 int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
399 memset(®s, 0, sizeof(regs));
401 regs.ebx = (unsigned long) fn;
402 regs.edx = (unsigned long) arg;
404 regs.xds = __USER_DS;
405 regs.xes = __USER_DS;
406 regs.xfs = __KERNEL_PERCPU;
408 regs.eip = (unsigned long) kernel_thread_helper;
409 regs.xcs = __KERNEL_CS | get_kernel_rpl();
410 regs.eflags = X86_EFLAGS_IF | X86_EFLAGS_SF | X86_EFLAGS_PF | 0x2;
412 /* Ok, create the new process.. */
413 return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, ®s, 0, NULL, NULL);
415 EXPORT_SYMBOL(kernel_thread);
418 * Free current thread data structures etc..
420 void exit_thread(void)
422 /* The process may have allocated an io port bitmap... nuke it. */
423 if (unlikely(test_thread_flag(TIF_IO_BITMAP))) {
424 struct task_struct *tsk = current;
425 struct thread_struct *t = &tsk->thread;
427 struct tss_struct *tss = &per_cpu(init_tss, cpu);
429 kfree(t->io_bitmap_ptr);
430 t->io_bitmap_ptr = NULL;
431 clear_thread_flag(TIF_IO_BITMAP);
433 * Careful, clear this in the TSS too:
435 memset(tss->io_bitmap, 0xff, tss->io_bitmap_max);
436 t->io_bitmap_max = 0;
437 tss->io_bitmap_owner = NULL;
438 tss->io_bitmap_max = 0;
439 tss->x86_tss.io_bitmap_base = INVALID_IO_BITMAP_OFFSET;
444 void flush_thread(void)
446 struct task_struct *tsk = current;
448 memset(tsk->thread.debugreg, 0, sizeof(unsigned long)*8);
449 memset(tsk->thread.tls_array, 0, sizeof(tsk->thread.tls_array));
450 clear_tsk_thread_flag(tsk, TIF_DEBUG);
452 * Forget coprocessor state..
458 void release_thread(struct task_struct *dead_task)
460 BUG_ON(dead_task->mm);
461 release_vm86_irqs(dead_task);
465 * This gets called before we allocate a new thread and copy
466 * the current task into it.
468 void prepare_to_copy(struct task_struct *tsk)
473 int copy_thread(int nr, unsigned long clone_flags, unsigned long esp,
474 unsigned long unused,
475 struct task_struct * p, struct pt_regs * regs)
477 struct pt_regs * childregs;
478 struct task_struct *tsk;
481 childregs = task_pt_regs(p);
484 childregs->esp = esp;
486 p->thread.esp = (unsigned long) childregs;
487 p->thread.esp0 = (unsigned long) (childregs+1);
489 p->thread.eip = (unsigned long) ret_from_fork;
491 savesegment(gs,p->thread.gs);
494 if (unlikely(test_tsk_thread_flag(tsk, TIF_IO_BITMAP))) {
495 p->thread.io_bitmap_ptr = kmemdup(tsk->thread.io_bitmap_ptr,
496 IO_BITMAP_BYTES, GFP_KERNEL);
497 if (!p->thread.io_bitmap_ptr) {
498 p->thread.io_bitmap_max = 0;
501 set_tsk_thread_flag(p, TIF_IO_BITMAP);
505 * Set a new TLS for the child thread?
507 if (clone_flags & CLONE_SETTLS) {
508 struct desc_struct *desc;
509 struct user_desc info;
513 if (copy_from_user(&info, (void __user *)childregs->esi, sizeof(info)))
516 if (LDT_empty(&info))
519 idx = info.entry_number;
520 if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX)
523 desc = p->thread.tls_array + idx - GDT_ENTRY_TLS_MIN;
524 desc->a = LDT_entry_a(&info);
525 desc->b = LDT_entry_b(&info);
530 if (err && p->thread.io_bitmap_ptr) {
531 kfree(p->thread.io_bitmap_ptr);
532 p->thread.io_bitmap_max = 0;
538 * fill in the user structure for a core dump..
540 void dump_thread(struct pt_regs * regs, struct user * dump)
544 /* changed the size calculations - should hopefully work better. lbt */
545 dump->magic = CMAGIC;
546 dump->start_code = 0;
547 dump->start_stack = regs->esp & ~(PAGE_SIZE - 1);
548 dump->u_tsize = ((unsigned long) current->mm->end_code) >> PAGE_SHIFT;
549 dump->u_dsize = ((unsigned long) (current->mm->brk + (PAGE_SIZE-1))) >> PAGE_SHIFT;
550 dump->u_dsize -= dump->u_tsize;
552 for (i = 0; i < 8; i++)
553 dump->u_debugreg[i] = current->thread.debugreg[i];
555 if (dump->start_stack < TASK_SIZE)
556 dump->u_ssize = ((unsigned long) (TASK_SIZE - dump->start_stack)) >> PAGE_SHIFT;
558 dump->regs.ebx = regs->ebx;
559 dump->regs.ecx = regs->ecx;
560 dump->regs.edx = regs->edx;
561 dump->regs.esi = regs->esi;
562 dump->regs.edi = regs->edi;
563 dump->regs.ebp = regs->ebp;
564 dump->regs.eax = regs->eax;
565 dump->regs.ds = regs->xds;
566 dump->regs.es = regs->xes;
567 dump->regs.fs = regs->xfs;
568 savesegment(gs,dump->regs.gs);
569 dump->regs.orig_eax = regs->orig_eax;
570 dump->regs.eip = regs->eip;
571 dump->regs.cs = regs->xcs;
572 dump->regs.eflags = regs->eflags;
573 dump->regs.esp = regs->esp;
574 dump->regs.ss = regs->xss;
576 dump->u_fpvalid = dump_fpu (regs, &dump->i387);
578 EXPORT_SYMBOL(dump_thread);
581 * Capture the user space registers if the task is not running (in user space)
583 int dump_task_regs(struct task_struct *tsk, elf_gregset_t *regs)
585 struct pt_regs ptregs = *task_pt_regs(tsk);
586 ptregs.xcs &= 0xffff;
587 ptregs.xds &= 0xffff;
588 ptregs.xes &= 0xffff;
589 ptregs.xss &= 0xffff;
591 elf_core_copy_regs(regs, &ptregs);
596 #ifdef CONFIG_SECCOMP
597 void hard_disable_TSC(void)
599 write_cr4(read_cr4() | X86_CR4_TSD);
601 void disable_TSC(void)
604 if (!test_and_set_thread_flag(TIF_NOTSC))
606 * Must flip the CPU state synchronously with
607 * TIF_NOTSC in the current running context.
612 void hard_enable_TSC(void)
614 write_cr4(read_cr4() & ~X86_CR4_TSD);
616 #endif /* CONFIG_SECCOMP */
619 __switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p,
620 struct tss_struct *tss)
622 struct thread_struct *next;
624 next = &next_p->thread;
626 if (test_tsk_thread_flag(next_p, TIF_DEBUG)) {
627 set_debugreg(next->debugreg[0], 0);
628 set_debugreg(next->debugreg[1], 1);
629 set_debugreg(next->debugreg[2], 2);
630 set_debugreg(next->debugreg[3], 3);
632 set_debugreg(next->debugreg[6], 6);
633 set_debugreg(next->debugreg[7], 7);
636 #ifdef CONFIG_SECCOMP
637 if (test_tsk_thread_flag(prev_p, TIF_NOTSC) ^
638 test_tsk_thread_flag(next_p, TIF_NOTSC)) {
639 /* prev and next are different */
640 if (test_tsk_thread_flag(next_p, TIF_NOTSC))
647 if (!test_tsk_thread_flag(next_p, TIF_IO_BITMAP)) {
649 * Disable the bitmap via an invalid offset. We still cache
650 * the previous bitmap owner and the IO bitmap contents:
652 tss->x86_tss.io_bitmap_base = INVALID_IO_BITMAP_OFFSET;
656 if (likely(next == tss->io_bitmap_owner)) {
658 * Previous owner of the bitmap (hence the bitmap content)
659 * matches the next task, we dont have to do anything but
660 * to set a valid offset in the TSS:
662 tss->x86_tss.io_bitmap_base = IO_BITMAP_OFFSET;
666 * Lazy TSS's I/O bitmap copy. We set an invalid offset here
667 * and we let the task to get a GPF in case an I/O instruction
668 * is performed. The handler of the GPF will verify that the
669 * faulting task has a valid I/O bitmap and, it true, does the
670 * real copy and restart the instruction. This will save us
671 * redundant copies when the currently switched task does not
672 * perform any I/O during its timeslice.
674 tss->x86_tss.io_bitmap_base = INVALID_IO_BITMAP_OFFSET_LAZY;
678 * switch_to(x,yn) should switch tasks from x to y.
680 * We fsave/fwait so that an exception goes off at the right time
681 * (as a call from the fsave or fwait in effect) rather than to
682 * the wrong process. Lazy FP saving no longer makes any sense
683 * with modern CPU's, and this simplifies a lot of things (SMP
684 * and UP become the same).
686 * NOTE! We used to use the x86 hardware context switching. The
687 * reason for not using it any more becomes apparent when you
688 * try to recover gracefully from saved state that is no longer
689 * valid (stale segment register values in particular). With the
690 * hardware task-switch, there is no way to fix up bad state in
691 * a reasonable manner.
693 * The fact that Intel documents the hardware task-switching to
694 * be slow is a fairly red herring - this code is not noticeably
695 * faster. However, there _is_ some room for improvement here,
696 * so the performance issues may eventually be a valid point.
697 * More important, however, is the fact that this allows us much
700 * The return value (in %eax) will be the "prev" task after
701 * the task-switch, and shows up in ret_from_fork in entry.S,
704 struct task_struct fastcall * __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
706 struct thread_struct *prev = &prev_p->thread,
707 *next = &next_p->thread;
708 int cpu = smp_processor_id();
709 struct tss_struct *tss = &per_cpu(init_tss, cpu);
711 /* never put a printk in __switch_to... printk() calls wake_up*() indirectly */
713 __unlazy_fpu(prev_p);
716 /* we're going to use this soon, after a few expensive things */
717 if (next_p->fpu_counter > 5)
718 prefetch(&next->i387.fxsave);
723 load_esp0(tss, next);
726 * Save away %gs. No need to save %fs, as it was saved on the
727 * stack on entry. No need to save %es and %ds, as those are
728 * always kernel segments while inside the kernel. Doing this
729 * before setting the new TLS descriptors avoids the situation
730 * where we temporarily have non-reloadable segments in %fs
731 * and %gs. This could be an issue if the NMI handler ever
732 * used %fs or %gs (it does not today), or if the kernel is
733 * running inside of a hypervisor layer.
735 savesegment(gs, prev->gs);
738 * Load the per-thread Thread-Local Storage descriptor.
743 * Restore IOPL if needed. In normal use, the flags restore
744 * in the switch assembly will handle this. But if the kernel
745 * is running virtualized at a non-zero CPL, the popf will
746 * not restore flags, so it must be done in a separate step.
748 if (get_kernel_rpl() && unlikely(prev->iopl != next->iopl))
749 set_iopl_mask(next->iopl);
752 * Now maybe handle debug registers and/or IO bitmaps
754 if (unlikely(task_thread_info(prev_p)->flags & _TIF_WORK_CTXSW_PREV ||
755 task_thread_info(next_p)->flags & _TIF_WORK_CTXSW_NEXT))
756 __switch_to_xtra(prev_p, next_p, tss);
759 * Leave lazy mode, flushing any hypercalls made here.
760 * This must be done before restoring TLS segments so
761 * the GDT and LDT are properly updated, and must be
762 * done before math_state_restore, so the TS bit is up
765 arch_leave_lazy_cpu_mode();
767 /* If the task has used fpu the last 5 timeslices, just do a full
768 * restore of the math state immediately to avoid the trap; the
769 * chances of needing FPU soon are obviously high now
771 if (next_p->fpu_counter > 5)
772 math_state_restore();
775 * Restore %gs if needed (which is common)
777 if (prev->gs | next->gs)
778 loadsegment(gs, next->gs);
780 x86_write_percpu(current_task, next_p);
785 asmlinkage int sys_fork(struct pt_regs regs)
787 return do_fork(SIGCHLD, regs.esp, ®s, 0, NULL, NULL);
790 asmlinkage int sys_clone(struct pt_regs regs)
792 unsigned long clone_flags;
794 int __user *parent_tidptr, *child_tidptr;
796 clone_flags = regs.ebx;
798 parent_tidptr = (int __user *)regs.edx;
799 child_tidptr = (int __user *)regs.edi;
802 return do_fork(clone_flags, newsp, ®s, 0, parent_tidptr, child_tidptr);
806 * This is trivial, and on the face of it looks like it
807 * could equally well be done in user mode.
809 * Not so, for quite unobvious reasons - register pressure.
810 * In user mode vfork() cannot have a stack frame, and if
811 * done by calling the "clone()" system call directly, you
812 * do not have enough call-clobbered registers to hold all
813 * the information you need.
815 asmlinkage int sys_vfork(struct pt_regs regs)
817 return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, regs.esp, ®s, 0, NULL, NULL);
821 * sys_execve() executes a new program.
823 asmlinkage int sys_execve(struct pt_regs regs)
828 filename = getname((char __user *) regs.ebx);
829 error = PTR_ERR(filename);
830 if (IS_ERR(filename))
832 error = do_execve(filename,
833 (char __user * __user *) regs.ecx,
834 (char __user * __user *) regs.edx,
838 current->ptrace &= ~PT_DTRACE;
839 task_unlock(current);
840 /* Make sure we don't return using sysenter.. */
841 set_thread_flag(TIF_IRET);
848 #define top_esp (THREAD_SIZE - sizeof(unsigned long))
849 #define top_ebp (THREAD_SIZE - 2*sizeof(unsigned long))
851 unsigned long get_wchan(struct task_struct *p)
853 unsigned long ebp, esp, eip;
854 unsigned long stack_page;
856 if (!p || p == current || p->state == TASK_RUNNING)
858 stack_page = (unsigned long)task_stack_page(p);
860 if (!stack_page || esp < stack_page || esp > top_esp+stack_page)
862 /* include/asm-i386/system.h:switch_to() pushes ebp last. */
863 ebp = *(unsigned long *) esp;
865 if (ebp < stack_page || ebp > top_ebp+stack_page)
867 eip = *(unsigned long *) (ebp+4);
868 if (!in_sched_functions(eip))
870 ebp = *(unsigned long *) ebp;
871 } while (count++ < 16);
876 * sys_alloc_thread_area: get a yet unused TLS descriptor index.
878 static int get_free_idx(void)
880 struct thread_struct *t = ¤t->thread;
883 for (idx = 0; idx < GDT_ENTRY_TLS_ENTRIES; idx++)
884 if (desc_empty(t->tls_array + idx))
885 return idx + GDT_ENTRY_TLS_MIN;
890 * Set a given TLS descriptor:
892 asmlinkage int sys_set_thread_area(struct user_desc __user *u_info)
894 struct thread_struct *t = ¤t->thread;
895 struct user_desc info;
896 struct desc_struct *desc;
899 if (copy_from_user(&info, u_info, sizeof(info)))
901 idx = info.entry_number;
904 * index -1 means the kernel should try to find and
905 * allocate an empty descriptor:
908 idx = get_free_idx();
911 if (put_user(idx, &u_info->entry_number))
915 if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX)
918 desc = t->tls_array + idx - GDT_ENTRY_TLS_MIN;
921 * We must not get preempted while modifying the TLS.
925 if (LDT_empty(&info)) {
929 desc->a = LDT_entry_a(&info);
930 desc->b = LDT_entry_b(&info);
940 * Get the current Thread-Local Storage area:
943 #define GET_BASE(desc) ( \
944 (((desc)->a >> 16) & 0x0000ffff) | \
945 (((desc)->b << 16) & 0x00ff0000) | \
946 ( (desc)->b & 0xff000000) )
948 #define GET_LIMIT(desc) ( \
949 ((desc)->a & 0x0ffff) | \
950 ((desc)->b & 0xf0000) )
952 #define GET_32BIT(desc) (((desc)->b >> 22) & 1)
953 #define GET_CONTENTS(desc) (((desc)->b >> 10) & 3)
954 #define GET_WRITABLE(desc) (((desc)->b >> 9) & 1)
955 #define GET_LIMIT_PAGES(desc) (((desc)->b >> 23) & 1)
956 #define GET_PRESENT(desc) (((desc)->b >> 15) & 1)
957 #define GET_USEABLE(desc) (((desc)->b >> 20) & 1)
959 asmlinkage int sys_get_thread_area(struct user_desc __user *u_info)
961 struct user_desc info;
962 struct desc_struct *desc;
965 if (get_user(idx, &u_info->entry_number))
967 if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX)
970 memset(&info, 0, sizeof(info));
972 desc = current->thread.tls_array + idx - GDT_ENTRY_TLS_MIN;
974 info.entry_number = idx;
975 info.base_addr = GET_BASE(desc);
976 info.limit = GET_LIMIT(desc);
977 info.seg_32bit = GET_32BIT(desc);
978 info.contents = GET_CONTENTS(desc);
979 info.read_exec_only = !GET_WRITABLE(desc);
980 info.limit_in_pages = GET_LIMIT_PAGES(desc);
981 info.seg_not_present = !GET_PRESENT(desc);
982 info.useable = GET_USEABLE(desc);
984 if (copy_to_user(u_info, &info, sizeof(info)))
989 unsigned long arch_align_stack(unsigned long sp)
991 if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
992 sp -= get_random_int() % 8192;
996 unsigned long arch_randomize_brk(struct mm_struct *mm)
998 unsigned long range_end = mm->brk + 0x02000000;
999 return randomize_range(mm->brk, range_end, 0) ? : mm->brk;