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 static void do_nothing(void *unused)
211 void cpu_idle_wait(void)
213 unsigned int cpu, this_cpu = get_cpu();
214 cpumask_t map, tmp = current->cpus_allowed;
216 set_cpus_allowed(current, cpumask_of_cpu(this_cpu));
220 for_each_online_cpu(cpu) {
221 per_cpu(cpu_idle_state, cpu) = 1;
225 __get_cpu_var(cpu_idle_state) = 0;
230 for_each_online_cpu(cpu) {
231 if (cpu_isset(cpu, map) && !per_cpu(cpu_idle_state, cpu))
234 cpus_and(map, map, cpu_online_map);
236 * We waited 1 sec, if a CPU still did not call idle
237 * it may be because it is in idle and not waking up
238 * because it has nothing to do.
239 * Give all the remaining CPUS a kick.
241 smp_call_function_mask(map, do_nothing, 0, 0);
242 } while (!cpus_empty(map));
244 set_cpus_allowed(current, tmp);
246 EXPORT_SYMBOL_GPL(cpu_idle_wait);
249 * This uses new MONITOR/MWAIT instructions on P4 processors with PNI,
250 * which can obviate IPI to trigger checking of need_resched.
251 * We execute MONITOR against need_resched and enter optimized wait state
252 * through MWAIT. Whenever someone changes need_resched, we would be woken
253 * up from MWAIT (without an IPI).
255 * New with Core Duo processors, MWAIT can take some hints based on CPU
258 void mwait_idle_with_hints(unsigned long eax, unsigned long ecx)
260 if (!need_resched()) {
261 __monitor((void *)¤t_thread_info()->flags, 0, 0);
268 /* Default MONITOR/MWAIT with no hints, used for default C1 state */
269 static void mwait_idle(void)
272 mwait_idle_with_hints(0, 0);
275 void __cpuinit select_idle_routine(const struct cpuinfo_x86 *c)
277 if (cpu_has(c, X86_FEATURE_MWAIT)) {
278 printk("monitor/mwait feature present.\n");
280 * Skip, if setup has overridden idle.
281 * One CPU supports mwait => All CPUs supports mwait
284 printk("using mwait in idle threads.\n");
285 pm_idle = mwait_idle;
290 static int __init idle_setup(char *str)
292 if (!strcmp(str, "poll")) {
293 printk("using polling idle threads.\n");
295 #ifdef CONFIG_X86_SMP
296 if (smp_num_siblings > 1)
297 printk("WARNING: polling idle and HT enabled, performance may degrade.\n");
299 } else if (!strcmp(str, "mwait"))
304 boot_option_idle_override = 1;
307 early_param("idle", idle_setup);
309 void __show_registers(struct pt_regs *regs, int all)
311 unsigned long cr0 = 0L, cr2 = 0L, cr3 = 0L, cr4 = 0L;
312 unsigned long d0, d1, d2, d3, d6, d7;
314 unsigned short ss, gs;
316 if (user_mode_vm(regs)) {
318 ss = regs->xss & 0xffff;
321 esp = (unsigned long) (®s->esp);
327 printk("Pid: %d, comm: %s %s (%s %.*s)\n",
328 task_pid_nr(current), current->comm,
329 print_tainted(), init_utsname()->release,
330 (int)strcspn(init_utsname()->version, " "),
331 init_utsname()->version);
333 printk("EIP: %04x:[<%08lx>] EFLAGS: %08lx CPU: %d\n",
334 0xffff & regs->xcs, regs->eip, regs->eflags,
336 print_symbol("EIP is at %s\n", regs->eip);
338 printk("EAX: %08lx EBX: %08lx ECX: %08lx EDX: %08lx\n",
339 regs->eax, regs->ebx, regs->ecx, regs->edx);
340 printk("ESI: %08lx EDI: %08lx EBP: %08lx ESP: %08lx\n",
341 regs->esi, regs->edi, regs->ebp, esp);
342 printk(" DS: %04x ES: %04x FS: %04x GS: %04x SS: %04x\n",
343 regs->xds & 0xffff, regs->xes & 0xffff,
344 regs->xfs & 0xffff, gs, ss);
352 cr4 = read_cr4_safe();
353 printk("CR0: %08lx CR2: %08lx CR3: %08lx CR4: %08lx\n",
360 printk("DR0: %08lx DR1: %08lx DR2: %08lx DR3: %08lx\n",
365 printk("DR6: %08lx DR7: %08lx\n",
369 void show_regs(struct pt_regs *regs)
371 __show_registers(regs, 1);
372 show_trace(NULL, regs, ®s->esp);
376 * This gets run with %ebx containing the
377 * function to call, and %edx containing
380 extern void kernel_thread_helper(void);
383 * Create a kernel thread
385 int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
389 memset(®s, 0, sizeof(regs));
391 regs.ebx = (unsigned long) fn;
392 regs.edx = (unsigned long) arg;
394 regs.xds = __USER_DS;
395 regs.xes = __USER_DS;
396 regs.xfs = __KERNEL_PERCPU;
398 regs.eip = (unsigned long) kernel_thread_helper;
399 regs.xcs = __KERNEL_CS | get_kernel_rpl();
400 regs.eflags = X86_EFLAGS_IF | X86_EFLAGS_SF | X86_EFLAGS_PF | 0x2;
402 /* Ok, create the new process.. */
403 return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, ®s, 0, NULL, NULL);
405 EXPORT_SYMBOL(kernel_thread);
408 * Free current thread data structures etc..
410 void exit_thread(void)
412 /* The process may have allocated an io port bitmap... nuke it. */
413 if (unlikely(test_thread_flag(TIF_IO_BITMAP))) {
414 struct task_struct *tsk = current;
415 struct thread_struct *t = &tsk->thread;
417 struct tss_struct *tss = &per_cpu(init_tss, cpu);
419 kfree(t->io_bitmap_ptr);
420 t->io_bitmap_ptr = NULL;
421 clear_thread_flag(TIF_IO_BITMAP);
423 * Careful, clear this in the TSS too:
425 memset(tss->io_bitmap, 0xff, tss->io_bitmap_max);
426 t->io_bitmap_max = 0;
427 tss->io_bitmap_owner = NULL;
428 tss->io_bitmap_max = 0;
429 tss->x86_tss.io_bitmap_base = INVALID_IO_BITMAP_OFFSET;
434 void flush_thread(void)
436 struct task_struct *tsk = current;
438 memset(tsk->thread.debugreg, 0, sizeof(unsigned long)*8);
439 memset(tsk->thread.tls_array, 0, sizeof(tsk->thread.tls_array));
440 clear_tsk_thread_flag(tsk, TIF_DEBUG);
442 * Forget coprocessor state..
448 void release_thread(struct task_struct *dead_task)
450 BUG_ON(dead_task->mm);
451 release_vm86_irqs(dead_task);
455 * This gets called before we allocate a new thread and copy
456 * the current task into it.
458 void prepare_to_copy(struct task_struct *tsk)
463 int copy_thread(int nr, unsigned long clone_flags, unsigned long esp,
464 unsigned long unused,
465 struct task_struct * p, struct pt_regs * regs)
467 struct pt_regs * childregs;
468 struct task_struct *tsk;
471 childregs = task_pt_regs(p);
474 childregs->esp = esp;
476 p->thread.esp = (unsigned long) childregs;
477 p->thread.esp0 = (unsigned long) (childregs+1);
479 p->thread.eip = (unsigned long) ret_from_fork;
481 savesegment(gs,p->thread.gs);
484 if (unlikely(test_tsk_thread_flag(tsk, TIF_IO_BITMAP))) {
485 p->thread.io_bitmap_ptr = kmemdup(tsk->thread.io_bitmap_ptr,
486 IO_BITMAP_BYTES, GFP_KERNEL);
487 if (!p->thread.io_bitmap_ptr) {
488 p->thread.io_bitmap_max = 0;
491 set_tsk_thread_flag(p, TIF_IO_BITMAP);
495 * Set a new TLS for the child thread?
497 if (clone_flags & CLONE_SETTLS) {
498 struct desc_struct *desc;
499 struct user_desc info;
503 if (copy_from_user(&info, (void __user *)childregs->esi, sizeof(info)))
506 if (LDT_empty(&info))
509 idx = info.entry_number;
510 if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX)
513 desc = p->thread.tls_array + idx - GDT_ENTRY_TLS_MIN;
514 desc->a = LDT_entry_a(&info);
515 desc->b = LDT_entry_b(&info);
520 if (err && p->thread.io_bitmap_ptr) {
521 kfree(p->thread.io_bitmap_ptr);
522 p->thread.io_bitmap_max = 0;
528 * fill in the user structure for a core dump..
530 void dump_thread(struct pt_regs * regs, struct user * dump)
534 /* changed the size calculations - should hopefully work better. lbt */
535 dump->magic = CMAGIC;
536 dump->start_code = 0;
537 dump->start_stack = regs->esp & ~(PAGE_SIZE - 1);
538 dump->u_tsize = ((unsigned long) current->mm->end_code) >> PAGE_SHIFT;
539 dump->u_dsize = ((unsigned long) (current->mm->brk + (PAGE_SIZE-1))) >> PAGE_SHIFT;
540 dump->u_dsize -= dump->u_tsize;
542 for (i = 0; i < 8; i++)
543 dump->u_debugreg[i] = current->thread.debugreg[i];
545 if (dump->start_stack < TASK_SIZE)
546 dump->u_ssize = ((unsigned long) (TASK_SIZE - dump->start_stack)) >> PAGE_SHIFT;
548 dump->regs.ebx = regs->ebx;
549 dump->regs.ecx = regs->ecx;
550 dump->regs.edx = regs->edx;
551 dump->regs.esi = regs->esi;
552 dump->regs.edi = regs->edi;
553 dump->regs.ebp = regs->ebp;
554 dump->regs.eax = regs->eax;
555 dump->regs.ds = regs->xds;
556 dump->regs.es = regs->xes;
557 dump->regs.fs = regs->xfs;
558 savesegment(gs,dump->regs.gs);
559 dump->regs.orig_eax = regs->orig_eax;
560 dump->regs.eip = regs->eip;
561 dump->regs.cs = regs->xcs;
562 dump->regs.eflags = regs->eflags;
563 dump->regs.esp = regs->esp;
564 dump->regs.ss = regs->xss;
566 dump->u_fpvalid = dump_fpu (regs, &dump->i387);
568 EXPORT_SYMBOL(dump_thread);
571 * Capture the user space registers if the task is not running (in user space)
573 int dump_task_regs(struct task_struct *tsk, elf_gregset_t *regs)
575 struct pt_regs ptregs = *task_pt_regs(tsk);
576 ptregs.xcs &= 0xffff;
577 ptregs.xds &= 0xffff;
578 ptregs.xes &= 0xffff;
579 ptregs.xss &= 0xffff;
581 elf_core_copy_regs(regs, &ptregs);
586 #ifdef CONFIG_SECCOMP
587 void hard_disable_TSC(void)
589 write_cr4(read_cr4() | X86_CR4_TSD);
591 void disable_TSC(void)
594 if (!test_and_set_thread_flag(TIF_NOTSC))
596 * Must flip the CPU state synchronously with
597 * TIF_NOTSC in the current running context.
602 void hard_enable_TSC(void)
604 write_cr4(read_cr4() & ~X86_CR4_TSD);
606 #endif /* CONFIG_SECCOMP */
609 __switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p,
610 struct tss_struct *tss)
612 struct thread_struct *next;
614 next = &next_p->thread;
616 if (test_tsk_thread_flag(next_p, TIF_DEBUG)) {
617 set_debugreg(next->debugreg[0], 0);
618 set_debugreg(next->debugreg[1], 1);
619 set_debugreg(next->debugreg[2], 2);
620 set_debugreg(next->debugreg[3], 3);
622 set_debugreg(next->debugreg[6], 6);
623 set_debugreg(next->debugreg[7], 7);
626 #ifdef CONFIG_SECCOMP
627 if (test_tsk_thread_flag(prev_p, TIF_NOTSC) ^
628 test_tsk_thread_flag(next_p, TIF_NOTSC)) {
629 /* prev and next are different */
630 if (test_tsk_thread_flag(next_p, TIF_NOTSC))
637 if (!test_tsk_thread_flag(next_p, TIF_IO_BITMAP)) {
639 * Disable the bitmap via an invalid offset. We still cache
640 * the previous bitmap owner and the IO bitmap contents:
642 tss->x86_tss.io_bitmap_base = INVALID_IO_BITMAP_OFFSET;
646 if (likely(next == tss->io_bitmap_owner)) {
648 * Previous owner of the bitmap (hence the bitmap content)
649 * matches the next task, we dont have to do anything but
650 * to set a valid offset in the TSS:
652 tss->x86_tss.io_bitmap_base = IO_BITMAP_OFFSET;
656 * Lazy TSS's I/O bitmap copy. We set an invalid offset here
657 * and we let the task to get a GPF in case an I/O instruction
658 * is performed. The handler of the GPF will verify that the
659 * faulting task has a valid I/O bitmap and, it true, does the
660 * real copy and restart the instruction. This will save us
661 * redundant copies when the currently switched task does not
662 * perform any I/O during its timeslice.
664 tss->x86_tss.io_bitmap_base = INVALID_IO_BITMAP_OFFSET_LAZY;
668 * switch_to(x,yn) should switch tasks from x to y.
670 * We fsave/fwait so that an exception goes off at the right time
671 * (as a call from the fsave or fwait in effect) rather than to
672 * the wrong process. Lazy FP saving no longer makes any sense
673 * with modern CPU's, and this simplifies a lot of things (SMP
674 * and UP become the same).
676 * NOTE! We used to use the x86 hardware context switching. The
677 * reason for not using it any more becomes apparent when you
678 * try to recover gracefully from saved state that is no longer
679 * valid (stale segment register values in particular). With the
680 * hardware task-switch, there is no way to fix up bad state in
681 * a reasonable manner.
683 * The fact that Intel documents the hardware task-switching to
684 * be slow is a fairly red herring - this code is not noticeably
685 * faster. However, there _is_ some room for improvement here,
686 * so the performance issues may eventually be a valid point.
687 * More important, however, is the fact that this allows us much
690 * The return value (in %eax) will be the "prev" task after
691 * the task-switch, and shows up in ret_from_fork in entry.S,
694 struct task_struct fastcall * __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
696 struct thread_struct *prev = &prev_p->thread,
697 *next = &next_p->thread;
698 int cpu = smp_processor_id();
699 struct tss_struct *tss = &per_cpu(init_tss, cpu);
701 /* never put a printk in __switch_to... printk() calls wake_up*() indirectly */
703 __unlazy_fpu(prev_p);
706 /* we're going to use this soon, after a few expensive things */
707 if (next_p->fpu_counter > 5)
708 prefetch(&next->i387.fxsave);
713 load_esp0(tss, next);
716 * Save away %gs. No need to save %fs, as it was saved on the
717 * stack on entry. No need to save %es and %ds, as those are
718 * always kernel segments while inside the kernel. Doing this
719 * before setting the new TLS descriptors avoids the situation
720 * where we temporarily have non-reloadable segments in %fs
721 * and %gs. This could be an issue if the NMI handler ever
722 * used %fs or %gs (it does not today), or if the kernel is
723 * running inside of a hypervisor layer.
725 savesegment(gs, prev->gs);
728 * Load the per-thread Thread-Local Storage descriptor.
733 * Restore IOPL if needed. In normal use, the flags restore
734 * in the switch assembly will handle this. But if the kernel
735 * is running virtualized at a non-zero CPL, the popf will
736 * not restore flags, so it must be done in a separate step.
738 if (get_kernel_rpl() && unlikely(prev->iopl != next->iopl))
739 set_iopl_mask(next->iopl);
742 * Now maybe handle debug registers and/or IO bitmaps
744 if (unlikely(task_thread_info(prev_p)->flags & _TIF_WORK_CTXSW_PREV ||
745 task_thread_info(next_p)->flags & _TIF_WORK_CTXSW_NEXT))
746 __switch_to_xtra(prev_p, next_p, tss);
749 * Leave lazy mode, flushing any hypercalls made here.
750 * This must be done before restoring TLS segments so
751 * the GDT and LDT are properly updated, and must be
752 * done before math_state_restore, so the TS bit is up
755 arch_leave_lazy_cpu_mode();
757 /* If the task has used fpu the last 5 timeslices, just do a full
758 * restore of the math state immediately to avoid the trap; the
759 * chances of needing FPU soon are obviously high now
761 if (next_p->fpu_counter > 5)
762 math_state_restore();
765 * Restore %gs if needed (which is common)
767 if (prev->gs | next->gs)
768 loadsegment(gs, next->gs);
770 x86_write_percpu(current_task, next_p);
775 asmlinkage int sys_fork(struct pt_regs regs)
777 return do_fork(SIGCHLD, regs.esp, ®s, 0, NULL, NULL);
780 asmlinkage int sys_clone(struct pt_regs regs)
782 unsigned long clone_flags;
784 int __user *parent_tidptr, *child_tidptr;
786 clone_flags = regs.ebx;
788 parent_tidptr = (int __user *)regs.edx;
789 child_tidptr = (int __user *)regs.edi;
792 return do_fork(clone_flags, newsp, ®s, 0, parent_tidptr, child_tidptr);
796 * This is trivial, and on the face of it looks like it
797 * could equally well be done in user mode.
799 * Not so, for quite unobvious reasons - register pressure.
800 * In user mode vfork() cannot have a stack frame, and if
801 * done by calling the "clone()" system call directly, you
802 * do not have enough call-clobbered registers to hold all
803 * the information you need.
805 asmlinkage int sys_vfork(struct pt_regs regs)
807 return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, regs.esp, ®s, 0, NULL, NULL);
811 * sys_execve() executes a new program.
813 asmlinkage int sys_execve(struct pt_regs regs)
818 filename = getname((char __user *) regs.ebx);
819 error = PTR_ERR(filename);
820 if (IS_ERR(filename))
822 error = do_execve(filename,
823 (char __user * __user *) regs.ecx,
824 (char __user * __user *) regs.edx,
828 current->ptrace &= ~PT_DTRACE;
829 task_unlock(current);
830 /* Make sure we don't return using sysenter.. */
831 set_thread_flag(TIF_IRET);
838 #define top_esp (THREAD_SIZE - sizeof(unsigned long))
839 #define top_ebp (THREAD_SIZE - 2*sizeof(unsigned long))
841 unsigned long get_wchan(struct task_struct *p)
843 unsigned long ebp, esp, eip;
844 unsigned long stack_page;
846 if (!p || p == current || p->state == TASK_RUNNING)
848 stack_page = (unsigned long)task_stack_page(p);
850 if (!stack_page || esp < stack_page || esp > top_esp+stack_page)
852 /* include/asm-i386/system.h:switch_to() pushes ebp last. */
853 ebp = *(unsigned long *) esp;
855 if (ebp < stack_page || ebp > top_ebp+stack_page)
857 eip = *(unsigned long *) (ebp+4);
858 if (!in_sched_functions(eip))
860 ebp = *(unsigned long *) ebp;
861 } while (count++ < 16);
866 * sys_alloc_thread_area: get a yet unused TLS descriptor index.
868 static int get_free_idx(void)
870 struct thread_struct *t = ¤t->thread;
873 for (idx = 0; idx < GDT_ENTRY_TLS_ENTRIES; idx++)
874 if (desc_empty(t->tls_array + idx))
875 return idx + GDT_ENTRY_TLS_MIN;
880 * Set a given TLS descriptor:
882 asmlinkage int sys_set_thread_area(struct user_desc __user *u_info)
884 struct thread_struct *t = ¤t->thread;
885 struct user_desc info;
886 struct desc_struct *desc;
889 if (copy_from_user(&info, u_info, sizeof(info)))
891 idx = info.entry_number;
894 * index -1 means the kernel should try to find and
895 * allocate an empty descriptor:
898 idx = get_free_idx();
901 if (put_user(idx, &u_info->entry_number))
905 if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX)
908 desc = t->tls_array + idx - GDT_ENTRY_TLS_MIN;
911 * We must not get preempted while modifying the TLS.
915 if (LDT_empty(&info)) {
919 desc->a = LDT_entry_a(&info);
920 desc->b = LDT_entry_b(&info);
930 * Get the current Thread-Local Storage area:
933 #define GET_BASE(desc) ( \
934 (((desc)->a >> 16) & 0x0000ffff) | \
935 (((desc)->b << 16) & 0x00ff0000) | \
936 ( (desc)->b & 0xff000000) )
938 #define GET_LIMIT(desc) ( \
939 ((desc)->a & 0x0ffff) | \
940 ((desc)->b & 0xf0000) )
942 #define GET_32BIT(desc) (((desc)->b >> 22) & 1)
943 #define GET_CONTENTS(desc) (((desc)->b >> 10) & 3)
944 #define GET_WRITABLE(desc) (((desc)->b >> 9) & 1)
945 #define GET_LIMIT_PAGES(desc) (((desc)->b >> 23) & 1)
946 #define GET_PRESENT(desc) (((desc)->b >> 15) & 1)
947 #define GET_USEABLE(desc) (((desc)->b >> 20) & 1)
949 asmlinkage int sys_get_thread_area(struct user_desc __user *u_info)
951 struct user_desc info;
952 struct desc_struct *desc;
955 if (get_user(idx, &u_info->entry_number))
957 if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX)
960 memset(&info, 0, sizeof(info));
962 desc = current->thread.tls_array + idx - GDT_ENTRY_TLS_MIN;
964 info.entry_number = idx;
965 info.base_addr = GET_BASE(desc);
966 info.limit = GET_LIMIT(desc);
967 info.seg_32bit = GET_32BIT(desc);
968 info.contents = GET_CONTENTS(desc);
969 info.read_exec_only = !GET_WRITABLE(desc);
970 info.limit_in_pages = GET_LIMIT_PAGES(desc);
971 info.seg_not_present = !GET_PRESENT(desc);
972 info.useable = GET_USEABLE(desc);
974 if (copy_to_user(u_info, &info, sizeof(info)))
979 unsigned long arch_align_stack(unsigned long sp)
981 if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
982 sp -= get_random_int() % 8192;