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>
59 asmlinkage void ret_from_fork(void) __asm__("ret_from_fork");
61 static int hlt_counter;
63 unsigned long boot_option_idle_override = 0;
64 EXPORT_SYMBOL(boot_option_idle_override);
66 DEFINE_PER_CPU(struct task_struct *, current_task) = &init_task;
67 EXPORT_PER_CPU_SYMBOL(current_task);
69 DEFINE_PER_CPU(int, cpu_number);
70 EXPORT_PER_CPU_SYMBOL(cpu_number);
73 * Return saved PC of a blocked thread.
75 unsigned long thread_saved_pc(struct task_struct *tsk)
77 return ((unsigned long *)tsk->thread.esp)[3];
81 * Powermanagement idle function, if any..
83 void (*pm_idle)(void);
84 EXPORT_SYMBOL(pm_idle);
85 static DEFINE_PER_CPU(unsigned int, cpu_idle_state);
87 void disable_hlt(void)
92 EXPORT_SYMBOL(disable_hlt);
99 EXPORT_SYMBOL(enable_hlt);
102 * We use this if we don't have any better
105 void default_idle(void)
107 if (!hlt_counter && boot_cpu_data.hlt_works_ok) {
108 current_thread_info()->status &= ~TS_POLLING;
110 * TS_POLLING-cleared state must be visible before we
117 safe_halt(); /* enables interrupts racelessly */
120 current_thread_info()->status |= TS_POLLING;
122 /* loop is done by the caller */
126 #ifdef CONFIG_APM_MODULE
127 EXPORT_SYMBOL(default_idle);
131 * On SMP it's slightly faster (but much more power-consuming!)
132 * to poll the ->work.need_resched flag instead of waiting for the
133 * cross-CPU IPI to arrive. Use this option with caution.
135 static void poll_idle (void)
140 #ifdef CONFIG_HOTPLUG_CPU
142 /* We don't actually take CPU down, just spin without interrupts. */
143 static inline void play_dead(void)
145 /* This must be done before dead CPU ack */
150 __get_cpu_var(cpu_state) = CPU_DEAD;
153 * With physical CPU hotplug, we should halt the cpu
160 static inline void play_dead(void)
164 #endif /* CONFIG_HOTPLUG_CPU */
167 * The idle thread. There's no useful work to be
168 * done, so just try to conserve power and have a
169 * low exit latency (ie sit in a loop waiting for
170 * somebody to say that they'd like to reschedule)
174 int cpu = smp_processor_id();
176 current_thread_info()->status |= TS_POLLING;
178 /* endless idle loop with no priority at all */
180 tick_nohz_stop_sched_tick();
181 while (!need_resched()) {
184 if (__get_cpu_var(cpu_idle_state))
185 __get_cpu_var(cpu_idle_state) = 0;
194 if (cpu_is_offline(cpu))
197 __get_cpu_var(irq_stat).idle_timestamp = jiffies;
200 tick_nohz_restart_sched_tick();
201 preempt_enable_no_resched();
207 void cpu_idle_wait(void)
209 unsigned int cpu, this_cpu = get_cpu();
210 cpumask_t map, tmp = current->cpus_allowed;
212 set_cpus_allowed(current, cpumask_of_cpu(this_cpu));
216 for_each_online_cpu(cpu) {
217 per_cpu(cpu_idle_state, cpu) = 1;
221 __get_cpu_var(cpu_idle_state) = 0;
226 for_each_online_cpu(cpu) {
227 if (cpu_isset(cpu, map) && !per_cpu(cpu_idle_state, cpu))
230 cpus_and(map, map, cpu_online_map);
231 } while (!cpus_empty(map));
233 set_cpus_allowed(current, tmp);
235 EXPORT_SYMBOL_GPL(cpu_idle_wait);
238 * This uses new MONITOR/MWAIT instructions on P4 processors with PNI,
239 * which can obviate IPI to trigger checking of need_resched.
240 * We execute MONITOR against need_resched and enter optimized wait state
241 * through MWAIT. Whenever someone changes need_resched, we would be woken
242 * up from MWAIT (without an IPI).
244 * New with Core Duo processors, MWAIT can take some hints based on CPU
247 void mwait_idle_with_hints(unsigned long eax, unsigned long ecx)
249 if (!need_resched()) {
250 __monitor((void *)¤t_thread_info()->flags, 0, 0);
257 /* Default MONITOR/MWAIT with no hints, used for default C1 state */
258 static void mwait_idle(void)
261 mwait_idle_with_hints(0, 0);
264 void __cpuinit select_idle_routine(const struct cpuinfo_x86 *c)
266 if (cpu_has(c, X86_FEATURE_MWAIT)) {
267 printk("monitor/mwait feature present.\n");
269 * Skip, if setup has overridden idle.
270 * One CPU supports mwait => All CPUs supports mwait
273 printk("using mwait in idle threads.\n");
274 pm_idle = mwait_idle;
279 static int __init idle_setup(char *str)
281 if (!strcmp(str, "poll")) {
282 printk("using polling idle threads.\n");
284 #ifdef CONFIG_X86_SMP
285 if (smp_num_siblings > 1)
286 printk("WARNING: polling idle and HT enabled, performance may degrade.\n");
288 } else if (!strcmp(str, "mwait"))
293 boot_option_idle_override = 1;
296 early_param("idle", idle_setup);
298 void __show_registers(struct pt_regs *regs, int all)
300 unsigned long cr0 = 0L, cr2 = 0L, cr3 = 0L, cr4 = 0L;
301 unsigned long d0, d1, d2, d3, d6, d7;
303 unsigned short ss, gs;
305 if (user_mode_vm(regs)) {
307 ss = regs->xss & 0xffff;
310 esp = (unsigned long) (®s->esp);
316 printk("Pid: %d, comm: %s %s (%s %.*s)\n",
317 task_pid_nr(current), current->comm,
318 print_tainted(), init_utsname()->release,
319 (int)strcspn(init_utsname()->version, " "),
320 init_utsname()->version);
322 printk("EIP: %04x:[<%08lx>] EFLAGS: %08lx CPU: %d\n",
323 0xffff & regs->xcs, regs->eip, regs->eflags,
325 print_symbol("EIP is at %s\n", regs->eip);
327 printk("EAX: %08lx EBX: %08lx ECX: %08lx EDX: %08lx\n",
328 regs->eax, regs->ebx, regs->ecx, regs->edx);
329 printk("ESI: %08lx EDI: %08lx EBP: %08lx ESP: %08lx\n",
330 regs->esi, regs->edi, regs->ebp, esp);
331 printk(" DS: %04x ES: %04x FS: %04x GS: %04x SS: %04x\n",
332 regs->xds & 0xffff, regs->xes & 0xffff,
333 regs->xfs & 0xffff, gs, ss);
341 cr4 = read_cr4_safe();
342 printk("CR0: %08lx CR2: %08lx CR3: %08lx CR4: %08lx\n",
349 printk("DR0: %08lx DR1: %08lx DR2: %08lx DR3: %08lx\n",
354 printk("DR6: %08lx DR7: %08lx\n",
358 void show_regs(struct pt_regs *regs)
360 __show_registers(regs, 1);
361 show_trace(NULL, regs, ®s->esp);
365 * This gets run with %ebx containing the
366 * function to call, and %edx containing
369 extern void kernel_thread_helper(void);
372 * Create a kernel thread
374 int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
378 memset(®s, 0, sizeof(regs));
380 regs.ebx = (unsigned long) fn;
381 regs.edx = (unsigned long) arg;
383 regs.xds = __USER_DS;
384 regs.xes = __USER_DS;
385 regs.xfs = __KERNEL_PERCPU;
387 regs.eip = (unsigned long) kernel_thread_helper;
388 regs.xcs = __KERNEL_CS | get_kernel_rpl();
389 regs.eflags = X86_EFLAGS_IF | X86_EFLAGS_SF | X86_EFLAGS_PF | 0x2;
391 /* Ok, create the new process.. */
392 return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, ®s, 0, NULL, NULL);
394 EXPORT_SYMBOL(kernel_thread);
397 * Free current thread data structures etc..
399 void exit_thread(void)
401 /* The process may have allocated an io port bitmap... nuke it. */
402 if (unlikely(test_thread_flag(TIF_IO_BITMAP))) {
403 struct task_struct *tsk = current;
404 struct thread_struct *t = &tsk->thread;
406 struct tss_struct *tss = &per_cpu(init_tss, cpu);
408 kfree(t->io_bitmap_ptr);
409 t->io_bitmap_ptr = NULL;
410 clear_thread_flag(TIF_IO_BITMAP);
412 * Careful, clear this in the TSS too:
414 memset(tss->io_bitmap, 0xff, tss->io_bitmap_max);
415 t->io_bitmap_max = 0;
416 tss->io_bitmap_owner = NULL;
417 tss->io_bitmap_max = 0;
418 tss->x86_tss.io_bitmap_base = INVALID_IO_BITMAP_OFFSET;
423 void flush_thread(void)
425 struct task_struct *tsk = current;
427 memset(tsk->thread.debugreg, 0, sizeof(unsigned long)*8);
428 memset(tsk->thread.tls_array, 0, sizeof(tsk->thread.tls_array));
429 clear_tsk_thread_flag(tsk, TIF_DEBUG);
431 * Forget coprocessor state..
437 void release_thread(struct task_struct *dead_task)
439 BUG_ON(dead_task->mm);
440 release_vm86_irqs(dead_task);
444 * This gets called before we allocate a new thread and copy
445 * the current task into it.
447 void prepare_to_copy(struct task_struct *tsk)
452 int copy_thread(int nr, unsigned long clone_flags, unsigned long esp,
453 unsigned long unused,
454 struct task_struct * p, struct pt_regs * regs)
456 struct pt_regs * childregs;
457 struct task_struct *tsk;
460 childregs = task_pt_regs(p);
463 childregs->esp = esp;
465 p->thread.esp = (unsigned long) childregs;
466 p->thread.esp0 = (unsigned long) (childregs+1);
468 p->thread.eip = (unsigned long) ret_from_fork;
470 savesegment(gs,p->thread.gs);
473 if (unlikely(test_tsk_thread_flag(tsk, TIF_IO_BITMAP))) {
474 p->thread.io_bitmap_ptr = kmemdup(tsk->thread.io_bitmap_ptr,
475 IO_BITMAP_BYTES, GFP_KERNEL);
476 if (!p->thread.io_bitmap_ptr) {
477 p->thread.io_bitmap_max = 0;
480 set_tsk_thread_flag(p, TIF_IO_BITMAP);
484 * Set a new TLS for the child thread?
486 if (clone_flags & CLONE_SETTLS) {
487 struct desc_struct *desc;
488 struct user_desc info;
492 if (copy_from_user(&info, (void __user *)childregs->esi, sizeof(info)))
495 if (LDT_empty(&info))
498 idx = info.entry_number;
499 if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX)
502 desc = p->thread.tls_array + idx - GDT_ENTRY_TLS_MIN;
503 desc->a = LDT_entry_a(&info);
504 desc->b = LDT_entry_b(&info);
509 if (err && p->thread.io_bitmap_ptr) {
510 kfree(p->thread.io_bitmap_ptr);
511 p->thread.io_bitmap_max = 0;
517 * fill in the user structure for a core dump..
519 void dump_thread(struct pt_regs * regs, struct user * dump)
523 /* changed the size calculations - should hopefully work better. lbt */
524 dump->magic = CMAGIC;
525 dump->start_code = 0;
526 dump->start_stack = regs->esp & ~(PAGE_SIZE - 1);
527 dump->u_tsize = ((unsigned long) current->mm->end_code) >> PAGE_SHIFT;
528 dump->u_dsize = ((unsigned long) (current->mm->brk + (PAGE_SIZE-1))) >> PAGE_SHIFT;
529 dump->u_dsize -= dump->u_tsize;
531 for (i = 0; i < 8; i++)
532 dump->u_debugreg[i] = current->thread.debugreg[i];
534 if (dump->start_stack < TASK_SIZE)
535 dump->u_ssize = ((unsigned long) (TASK_SIZE - dump->start_stack)) >> PAGE_SHIFT;
537 dump->regs.ebx = regs->ebx;
538 dump->regs.ecx = regs->ecx;
539 dump->regs.edx = regs->edx;
540 dump->regs.esi = regs->esi;
541 dump->regs.edi = regs->edi;
542 dump->regs.ebp = regs->ebp;
543 dump->regs.eax = regs->eax;
544 dump->regs.ds = regs->xds;
545 dump->regs.es = regs->xes;
546 dump->regs.fs = regs->xfs;
547 savesegment(gs,dump->regs.gs);
548 dump->regs.orig_eax = regs->orig_eax;
549 dump->regs.eip = regs->eip;
550 dump->regs.cs = regs->xcs;
551 dump->regs.eflags = regs->eflags;
552 dump->regs.esp = regs->esp;
553 dump->regs.ss = regs->xss;
555 dump->u_fpvalid = dump_fpu (regs, &dump->i387);
557 EXPORT_SYMBOL(dump_thread);
560 * Capture the user space registers if the task is not running (in user space)
562 int dump_task_regs(struct task_struct *tsk, elf_gregset_t *regs)
564 struct pt_regs ptregs = *task_pt_regs(tsk);
565 ptregs.xcs &= 0xffff;
566 ptregs.xds &= 0xffff;
567 ptregs.xes &= 0xffff;
568 ptregs.xss &= 0xffff;
570 elf_core_copy_regs(regs, &ptregs);
575 #ifdef CONFIG_SECCOMP
576 void hard_disable_TSC(void)
578 write_cr4(read_cr4() | X86_CR4_TSD);
580 void disable_TSC(void)
583 if (!test_and_set_thread_flag(TIF_NOTSC))
585 * Must flip the CPU state synchronously with
586 * TIF_NOTSC in the current running context.
591 void hard_enable_TSC(void)
593 write_cr4(read_cr4() & ~X86_CR4_TSD);
595 #endif /* CONFIG_SECCOMP */
598 __switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p,
599 struct tss_struct *tss)
601 struct thread_struct *next;
603 next = &next_p->thread;
605 if (test_tsk_thread_flag(next_p, TIF_DEBUG)) {
606 set_debugreg(next->debugreg[0], 0);
607 set_debugreg(next->debugreg[1], 1);
608 set_debugreg(next->debugreg[2], 2);
609 set_debugreg(next->debugreg[3], 3);
611 set_debugreg(next->debugreg[6], 6);
612 set_debugreg(next->debugreg[7], 7);
615 #ifdef CONFIG_SECCOMP
616 if (test_tsk_thread_flag(prev_p, TIF_NOTSC) ^
617 test_tsk_thread_flag(next_p, TIF_NOTSC)) {
618 /* prev and next are different */
619 if (test_tsk_thread_flag(next_p, TIF_NOTSC))
626 if (!test_tsk_thread_flag(next_p, TIF_IO_BITMAP)) {
628 * Disable the bitmap via an invalid offset. We still cache
629 * the previous bitmap owner and the IO bitmap contents:
631 tss->x86_tss.io_bitmap_base = INVALID_IO_BITMAP_OFFSET;
635 if (likely(next == tss->io_bitmap_owner)) {
637 * Previous owner of the bitmap (hence the bitmap content)
638 * matches the next task, we dont have to do anything but
639 * to set a valid offset in the TSS:
641 tss->x86_tss.io_bitmap_base = IO_BITMAP_OFFSET;
645 * Lazy TSS's I/O bitmap copy. We set an invalid offset here
646 * and we let the task to get a GPF in case an I/O instruction
647 * is performed. The handler of the GPF will verify that the
648 * faulting task has a valid I/O bitmap and, it true, does the
649 * real copy and restart the instruction. This will save us
650 * redundant copies when the currently switched task does not
651 * perform any I/O during its timeslice.
653 tss->x86_tss.io_bitmap_base = INVALID_IO_BITMAP_OFFSET_LAZY;
657 * switch_to(x,yn) should switch tasks from x to y.
659 * We fsave/fwait so that an exception goes off at the right time
660 * (as a call from the fsave or fwait in effect) rather than to
661 * the wrong process. Lazy FP saving no longer makes any sense
662 * with modern CPU's, and this simplifies a lot of things (SMP
663 * and UP become the same).
665 * NOTE! We used to use the x86 hardware context switching. The
666 * reason for not using it any more becomes apparent when you
667 * try to recover gracefully from saved state that is no longer
668 * valid (stale segment register values in particular). With the
669 * hardware task-switch, there is no way to fix up bad state in
670 * a reasonable manner.
672 * The fact that Intel documents the hardware task-switching to
673 * be slow is a fairly red herring - this code is not noticeably
674 * faster. However, there _is_ some room for improvement here,
675 * so the performance issues may eventually be a valid point.
676 * More important, however, is the fact that this allows us much
679 * The return value (in %eax) will be the "prev" task after
680 * the task-switch, and shows up in ret_from_fork in entry.S,
683 struct task_struct fastcall * __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
685 struct thread_struct *prev = &prev_p->thread,
686 *next = &next_p->thread;
687 int cpu = smp_processor_id();
688 struct tss_struct *tss = &per_cpu(init_tss, cpu);
690 /* never put a printk in __switch_to... printk() calls wake_up*() indirectly */
692 __unlazy_fpu(prev_p);
695 /* we're going to use this soon, after a few expensive things */
696 if (next_p->fpu_counter > 5)
697 prefetch(&next->i387.fxsave);
702 load_esp0(tss, next);
705 * Save away %gs. No need to save %fs, as it was saved on the
706 * stack on entry. No need to save %es and %ds, as those are
707 * always kernel segments while inside the kernel. Doing this
708 * before setting the new TLS descriptors avoids the situation
709 * where we temporarily have non-reloadable segments in %fs
710 * and %gs. This could be an issue if the NMI handler ever
711 * used %fs or %gs (it does not today), or if the kernel is
712 * running inside of a hypervisor layer.
714 savesegment(gs, prev->gs);
717 * Load the per-thread Thread-Local Storage descriptor.
722 * Restore IOPL if needed. In normal use, the flags restore
723 * in the switch assembly will handle this. But if the kernel
724 * is running virtualized at a non-zero CPL, the popf will
725 * not restore flags, so it must be done in a separate step.
727 if (get_kernel_rpl() && unlikely(prev->iopl != next->iopl))
728 set_iopl_mask(next->iopl);
731 * Now maybe handle debug registers and/or IO bitmaps
733 if (unlikely(task_thread_info(prev_p)->flags & _TIF_WORK_CTXSW_PREV ||
734 task_thread_info(next_p)->flags & _TIF_WORK_CTXSW_NEXT))
735 __switch_to_xtra(prev_p, next_p, tss);
738 * Leave lazy mode, flushing any hypercalls made here.
739 * This must be done before restoring TLS segments so
740 * the GDT and LDT are properly updated, and must be
741 * done before math_state_restore, so the TS bit is up
744 arch_leave_lazy_cpu_mode();
746 /* If the task has used fpu the last 5 timeslices, just do a full
747 * restore of the math state immediately to avoid the trap; the
748 * chances of needing FPU soon are obviously high now
750 if (next_p->fpu_counter > 5)
751 math_state_restore();
754 * Restore %gs if needed (which is common)
756 if (prev->gs | next->gs)
757 loadsegment(gs, next->gs);
759 x86_write_percpu(current_task, next_p);
764 asmlinkage int sys_fork(struct pt_regs regs)
766 return do_fork(SIGCHLD, regs.esp, ®s, 0, NULL, NULL);
769 asmlinkage int sys_clone(struct pt_regs regs)
771 unsigned long clone_flags;
773 int __user *parent_tidptr, *child_tidptr;
775 clone_flags = regs.ebx;
777 parent_tidptr = (int __user *)regs.edx;
778 child_tidptr = (int __user *)regs.edi;
781 return do_fork(clone_flags, newsp, ®s, 0, parent_tidptr, child_tidptr);
785 * This is trivial, and on the face of it looks like it
786 * could equally well be done in user mode.
788 * Not so, for quite unobvious reasons - register pressure.
789 * In user mode vfork() cannot have a stack frame, and if
790 * done by calling the "clone()" system call directly, you
791 * do not have enough call-clobbered registers to hold all
792 * the information you need.
794 asmlinkage int sys_vfork(struct pt_regs regs)
796 return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, regs.esp, ®s, 0, NULL, NULL);
800 * sys_execve() executes a new program.
802 asmlinkage int sys_execve(struct pt_regs regs)
807 filename = getname((char __user *) regs.ebx);
808 error = PTR_ERR(filename);
809 if (IS_ERR(filename))
811 error = do_execve(filename,
812 (char __user * __user *) regs.ecx,
813 (char __user * __user *) regs.edx,
817 current->ptrace &= ~PT_DTRACE;
818 task_unlock(current);
819 /* Make sure we don't return using sysenter.. */
820 set_thread_flag(TIF_IRET);
827 #define top_esp (THREAD_SIZE - sizeof(unsigned long))
828 #define top_ebp (THREAD_SIZE - 2*sizeof(unsigned long))
830 unsigned long get_wchan(struct task_struct *p)
832 unsigned long ebp, esp, eip;
833 unsigned long stack_page;
835 if (!p || p == current || p->state == TASK_RUNNING)
837 stack_page = (unsigned long)task_stack_page(p);
839 if (!stack_page || esp < stack_page || esp > top_esp+stack_page)
841 /* include/asm-i386/system.h:switch_to() pushes ebp last. */
842 ebp = *(unsigned long *) esp;
844 if (ebp < stack_page || ebp > top_ebp+stack_page)
846 eip = *(unsigned long *) (ebp+4);
847 if (!in_sched_functions(eip))
849 ebp = *(unsigned long *) ebp;
850 } while (count++ < 16);
855 * sys_alloc_thread_area: get a yet unused TLS descriptor index.
857 static int get_free_idx(void)
859 struct thread_struct *t = ¤t->thread;
862 for (idx = 0; idx < GDT_ENTRY_TLS_ENTRIES; idx++)
863 if (desc_empty(t->tls_array + idx))
864 return idx + GDT_ENTRY_TLS_MIN;
869 * Set a given TLS descriptor:
871 asmlinkage int sys_set_thread_area(struct user_desc __user *u_info)
873 struct thread_struct *t = ¤t->thread;
874 struct user_desc info;
875 struct desc_struct *desc;
878 if (copy_from_user(&info, u_info, sizeof(info)))
880 idx = info.entry_number;
883 * index -1 means the kernel should try to find and
884 * allocate an empty descriptor:
887 idx = get_free_idx();
890 if (put_user(idx, &u_info->entry_number))
894 if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX)
897 desc = t->tls_array + idx - GDT_ENTRY_TLS_MIN;
900 * We must not get preempted while modifying the TLS.
904 if (LDT_empty(&info)) {
908 desc->a = LDT_entry_a(&info);
909 desc->b = LDT_entry_b(&info);
919 * Get the current Thread-Local Storage area:
922 #define GET_BASE(desc) ( \
923 (((desc)->a >> 16) & 0x0000ffff) | \
924 (((desc)->b << 16) & 0x00ff0000) | \
925 ( (desc)->b & 0xff000000) )
927 #define GET_LIMIT(desc) ( \
928 ((desc)->a & 0x0ffff) | \
929 ((desc)->b & 0xf0000) )
931 #define GET_32BIT(desc) (((desc)->b >> 22) & 1)
932 #define GET_CONTENTS(desc) (((desc)->b >> 10) & 3)
933 #define GET_WRITABLE(desc) (((desc)->b >> 9) & 1)
934 #define GET_LIMIT_PAGES(desc) (((desc)->b >> 23) & 1)
935 #define GET_PRESENT(desc) (((desc)->b >> 15) & 1)
936 #define GET_USEABLE(desc) (((desc)->b >> 20) & 1)
938 asmlinkage int sys_get_thread_area(struct user_desc __user *u_info)
940 struct user_desc info;
941 struct desc_struct *desc;
944 if (get_user(idx, &u_info->entry_number))
946 if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX)
949 memset(&info, 0, sizeof(info));
951 desc = current->thread.tls_array + idx - GDT_ENTRY_TLS_MIN;
953 info.entry_number = idx;
954 info.base_addr = GET_BASE(desc);
955 info.limit = GET_LIMIT(desc);
956 info.seg_32bit = GET_32BIT(desc);
957 info.contents = GET_CONTENTS(desc);
958 info.read_exec_only = !GET_WRITABLE(desc);
959 info.limit_in_pages = GET_LIMIT_PAGES(desc);
960 info.seg_not_present = !GET_PRESENT(desc);
961 info.useable = GET_USEABLE(desc);
963 if (copy_to_user(u_info, &info, sizeof(info)))
968 unsigned long arch_align_stack(unsigned long sp)
970 if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
971 sp -= get_random_int() % 8192;