2 * linux/arch/i386/kernel/process.c
4 * Copyright (C) 1995 Linus Torvalds
6 * Pentium III FXSR, SSE support
7 * Gareth Hughes <gareth@valinux.com>, May 2000
11 * This file handles the architecture-dependent parts of process handling..
16 #include <linux/cpu.h>
17 #include <linux/errno.h>
18 #include <linux/sched.h>
20 #include <linux/kernel.h>
22 #include <linux/elfcore.h>
23 #include <linux/smp.h>
24 #include <linux/smp_lock.h>
25 #include <linux/stddef.h>
26 #include <linux/slab.h>
27 #include <linux/vmalloc.h>
28 #include <linux/user.h>
29 #include <linux/a.out.h>
30 #include <linux/interrupt.h>
31 #include <linux/config.h>
32 #include <linux/utsname.h>
33 #include <linux/delay.h>
34 #include <linux/reboot.h>
35 #include <linux/init.h>
36 #include <linux/mc146818rtc.h>
37 #include <linux/module.h>
38 #include <linux/kallsyms.h>
39 #include <linux/ptrace.h>
40 #include <linux/random.h>
41 #include <linux/kprobes.h>
43 #include <asm/uaccess.h>
44 #include <asm/pgtable.h>
45 #include <asm/system.h>
48 #include <asm/processor.h>
52 #ifdef CONFIG_MATH_EMULATION
53 #include <asm/math_emu.h>
56 #include <linux/err.h>
58 #include <asm/tlbflush.h>
61 asmlinkage
void ret_from_fork(void) __asm__("ret_from_fork");
63 static int hlt_counter
;
65 unsigned long boot_option_idle_override
= 0;
66 EXPORT_SYMBOL(boot_option_idle_override
);
69 * Return saved PC of a blocked thread.
71 unsigned long thread_saved_pc(struct task_struct
*tsk
)
73 return ((unsigned long *)tsk
->thread
.esp
)[3];
77 * Powermanagement idle function, if any..
79 void (*pm_idle
)(void);
80 EXPORT_SYMBOL(pm_idle
);
81 static DEFINE_PER_CPU(unsigned int, cpu_idle_state
);
83 void disable_hlt(void)
88 EXPORT_SYMBOL(disable_hlt
);
95 EXPORT_SYMBOL(enable_hlt
);
98 * We use this if we don't have any better
101 void default_idle(void)
105 if (!hlt_counter
&& boot_cpu_data
.hlt_works_ok
) {
106 clear_thread_flag(TIF_POLLING_NRFLAG
);
107 smp_mb__after_clear_bit();
108 while (!need_resched()) {
115 set_thread_flag(TIF_POLLING_NRFLAG
);
117 while (!need_resched())
121 #ifdef CONFIG_APM_MODULE
122 EXPORT_SYMBOL(default_idle
);
126 * On SMP it's slightly faster (but much more power-consuming!)
127 * to poll the ->work.need_resched flag instead of waiting for the
128 * cross-CPU IPI to arrive. Use this option with caution.
130 static void poll_idle (void)
139 : : "i"(_TIF_NEED_RESCHED
), "m" (current_thread_info()->flags
));
142 #ifdef CONFIG_HOTPLUG_CPU
144 /* We don't actually take CPU down, just spin without interrupts. */
145 static inline void play_dead(void)
147 /* This must be done before dead CPU ack */
152 __get_cpu_var(cpu_state
) = CPU_DEAD
;
155 * With physical CPU hotplug, we should halt the cpu
162 static inline void play_dead(void)
166 #endif /* CONFIG_HOTPLUG_CPU */
169 * The idle thread. There's no useful work to be
170 * done, so just try to conserve power and have a
171 * low exit latency (ie sit in a loop waiting for
172 * somebody to say that they'd like to reschedule)
176 int cpu
= smp_processor_id();
178 set_thread_flag(TIF_POLLING_NRFLAG
);
180 /* endless idle loop with no priority at all */
182 while (!need_resched()) {
185 if (__get_cpu_var(cpu_idle_state
))
186 __get_cpu_var(cpu_idle_state
) = 0;
194 if (cpu_is_offline(cpu
))
197 __get_cpu_var(irq_stat
).idle_timestamp
= jiffies
;
200 preempt_enable_no_resched();
206 void cpu_idle_wait(void)
208 unsigned int cpu
, this_cpu
= get_cpu();
211 set_cpus_allowed(current
, cpumask_of_cpu(this_cpu
));
215 for_each_online_cpu(cpu
) {
216 per_cpu(cpu_idle_state
, cpu
) = 1;
220 __get_cpu_var(cpu_idle_state
) = 0;
225 for_each_online_cpu(cpu
) {
226 if (cpu_isset(cpu
, map
) && !per_cpu(cpu_idle_state
, cpu
))
229 cpus_and(map
, map
, cpu_online_map
);
230 } while (!cpus_empty(map
));
232 EXPORT_SYMBOL_GPL(cpu_idle_wait
);
235 * This uses new MONITOR/MWAIT instructions on P4 processors with PNI,
236 * which can obviate IPI to trigger checking of need_resched.
237 * We execute MONITOR against need_resched and enter optimized wait state
238 * through MWAIT. Whenever someone changes need_resched, we would be woken
239 * up from MWAIT (without an IPI).
241 static void mwait_idle(void)
245 while (!need_resched()) {
246 __monitor((void *)¤t_thread_info()->flags
, 0, 0);
254 void __devinit
select_idle_routine(const struct cpuinfo_x86
*c
)
256 if (cpu_has(c
, X86_FEATURE_MWAIT
)) {
257 printk("monitor/mwait feature present.\n");
259 * Skip, if setup has overridden idle.
260 * One CPU supports mwait => All CPUs supports mwait
263 printk("using mwait in idle threads.\n");
264 pm_idle
= mwait_idle
;
269 static int __init
idle_setup (char *str
)
271 if (!strncmp(str
, "poll", 4)) {
272 printk("using polling idle threads.\n");
274 #ifdef CONFIG_X86_SMP
275 if (smp_num_siblings
> 1)
276 printk("WARNING: polling idle and HT enabled, performance may degrade.\n");
278 } else if (!strncmp(str
, "halt", 4)) {
279 printk("using halt in idle threads.\n");
280 pm_idle
= default_idle
;
283 boot_option_idle_override
= 1;
287 __setup("idle=", idle_setup
);
289 void show_regs(struct pt_regs
* regs
)
291 unsigned long cr0
= 0L, cr2
= 0L, cr3
= 0L, cr4
= 0L;
294 printk("Pid: %d, comm: %20s\n", current
->pid
, current
->comm
);
295 printk("EIP: %04x:[<%08lx>] CPU: %d\n",0xffff & regs
->xcs
,regs
->eip
, smp_processor_id());
296 print_symbol("EIP is at %s\n", regs
->eip
);
299 printk(" ESP: %04x:%08lx",0xffff & regs
->xss
,regs
->esp
);
300 printk(" EFLAGS: %08lx %s (%s)\n",
301 regs
->eflags
, print_tainted(), system_utsname
.release
);
302 printk("EAX: %08lx EBX: %08lx ECX: %08lx EDX: %08lx\n",
303 regs
->eax
,regs
->ebx
,regs
->ecx
,regs
->edx
);
304 printk("ESI: %08lx EDI: %08lx EBP: %08lx",
305 regs
->esi
, regs
->edi
, regs
->ebp
);
306 printk(" DS: %04x ES: %04x\n",
307 0xffff & regs
->xds
,0xffff & regs
->xes
);
312 cr4
= read_cr4_safe();
313 printk("CR0: %08lx CR2: %08lx CR3: %08lx CR4: %08lx\n", cr0
, cr2
, cr3
, cr4
);
314 show_trace(NULL
, ®s
->esp
);
318 * This gets run with %ebx containing the
319 * function to call, and %edx containing
322 extern void kernel_thread_helper(void);
323 __asm__(".section .text\n"
325 "kernel_thread_helper:\n\t"
334 * Create a kernel thread
336 int kernel_thread(int (*fn
)(void *), void * arg
, unsigned long flags
)
340 memset(®s
, 0, sizeof(regs
));
342 regs
.ebx
= (unsigned long) fn
;
343 regs
.edx
= (unsigned long) arg
;
345 regs
.xds
= __USER_DS
;
346 regs
.xes
= __USER_DS
;
348 regs
.eip
= (unsigned long) kernel_thread_helper
;
349 regs
.xcs
= __KERNEL_CS
;
350 regs
.eflags
= X86_EFLAGS_IF
| X86_EFLAGS_SF
| X86_EFLAGS_PF
| 0x2;
352 /* Ok, create the new process.. */
353 return do_fork(flags
| CLONE_VM
| CLONE_UNTRACED
, 0, ®s
, 0, NULL
, NULL
);
355 EXPORT_SYMBOL(kernel_thread
);
358 * Free current thread data structures etc..
360 void exit_thread(void)
362 struct task_struct
*tsk
= current
;
363 struct thread_struct
*t
= &tsk
->thread
;
366 * Remove function-return probe instances associated with this task
367 * and put them back on the free list. Do not insert an exit probe for
368 * this function, it will be disabled by kprobe_flush_task if you do.
370 kprobe_flush_task(tsk
);
372 /* The process may have allocated an io port bitmap... nuke it. */
373 if (unlikely(NULL
!= t
->io_bitmap_ptr
)) {
375 struct tss_struct
*tss
= &per_cpu(init_tss
, cpu
);
377 kfree(t
->io_bitmap_ptr
);
378 t
->io_bitmap_ptr
= NULL
;
380 * Careful, clear this in the TSS too:
382 memset(tss
->io_bitmap
, 0xff, tss
->io_bitmap_max
);
383 t
->io_bitmap_max
= 0;
384 tss
->io_bitmap_owner
= NULL
;
385 tss
->io_bitmap_max
= 0;
386 tss
->io_bitmap_base
= INVALID_IO_BITMAP_OFFSET
;
391 void flush_thread(void)
393 struct task_struct
*tsk
= current
;
395 memset(tsk
->thread
.debugreg
, 0, sizeof(unsigned long)*8);
396 memset(tsk
->thread
.tls_array
, 0, sizeof(tsk
->thread
.tls_array
));
398 * Forget coprocessor state..
404 void release_thread(struct task_struct
*dead_task
)
406 BUG_ON(dead_task
->mm
);
407 release_vm86_irqs(dead_task
);
411 * This gets called before we allocate a new thread and copy
412 * the current task into it.
414 void prepare_to_copy(struct task_struct
*tsk
)
419 int copy_thread(int nr
, unsigned long clone_flags
, unsigned long esp
,
420 unsigned long unused
,
421 struct task_struct
* p
, struct pt_regs
* regs
)
423 struct pt_regs
* childregs
;
424 struct task_struct
*tsk
;
427 childregs
= ((struct pt_regs
*) (THREAD_SIZE
+ (unsigned long) p
->thread_info
)) - 1;
429 * The below -8 is to reserve 8 bytes on top of the ring0 stack.
430 * This is necessary to guarantee that the entire "struct pt_regs"
431 * is accessable even if the CPU haven't stored the SS/ESP registers
432 * on the stack (interrupt gate does not save these registers
433 * when switching to the same priv ring).
434 * Therefore beware: accessing the xss/esp fields of the
435 * "struct pt_regs" is possible, but they may contain the
436 * completely wrong values.
438 childregs
= (struct pt_regs
*) ((unsigned long) childregs
- 8);
441 childregs
->esp
= esp
;
443 p
->thread
.esp
= (unsigned long) childregs
;
444 p
->thread
.esp0
= (unsigned long) (childregs
+1);
446 p
->thread
.eip
= (unsigned long) ret_from_fork
;
448 savesegment(fs
,p
->thread
.fs
);
449 savesegment(gs
,p
->thread
.gs
);
452 if (unlikely(NULL
!= tsk
->thread
.io_bitmap_ptr
)) {
453 p
->thread
.io_bitmap_ptr
= kmalloc(IO_BITMAP_BYTES
, GFP_KERNEL
);
454 if (!p
->thread
.io_bitmap_ptr
) {
455 p
->thread
.io_bitmap_max
= 0;
458 memcpy(p
->thread
.io_bitmap_ptr
, tsk
->thread
.io_bitmap_ptr
,
463 * Set a new TLS for the child thread?
465 if (clone_flags
& CLONE_SETTLS
) {
466 struct desc_struct
*desc
;
467 struct user_desc info
;
471 if (copy_from_user(&info
, (void __user
*)childregs
->esi
, sizeof(info
)))
474 if (LDT_empty(&info
))
477 idx
= info
.entry_number
;
478 if (idx
< GDT_ENTRY_TLS_MIN
|| idx
> GDT_ENTRY_TLS_MAX
)
481 desc
= p
->thread
.tls_array
+ idx
- GDT_ENTRY_TLS_MIN
;
482 desc
->a
= LDT_entry_a(&info
);
483 desc
->b
= LDT_entry_b(&info
);
488 if (err
&& p
->thread
.io_bitmap_ptr
) {
489 kfree(p
->thread
.io_bitmap_ptr
);
490 p
->thread
.io_bitmap_max
= 0;
496 * fill in the user structure for a core dump..
498 void dump_thread(struct pt_regs
* regs
, struct user
* dump
)
502 /* changed the size calculations - should hopefully work better. lbt */
503 dump
->magic
= CMAGIC
;
504 dump
->start_code
= 0;
505 dump
->start_stack
= regs
->esp
& ~(PAGE_SIZE
- 1);
506 dump
->u_tsize
= ((unsigned long) current
->mm
->end_code
) >> PAGE_SHIFT
;
507 dump
->u_dsize
= ((unsigned long) (current
->mm
->brk
+ (PAGE_SIZE
-1))) >> PAGE_SHIFT
;
508 dump
->u_dsize
-= dump
->u_tsize
;
510 for (i
= 0; i
< 8; i
++)
511 dump
->u_debugreg
[i
] = current
->thread
.debugreg
[i
];
513 if (dump
->start_stack
< TASK_SIZE
)
514 dump
->u_ssize
= ((unsigned long) (TASK_SIZE
- dump
->start_stack
)) >> PAGE_SHIFT
;
516 dump
->regs
.ebx
= regs
->ebx
;
517 dump
->regs
.ecx
= regs
->ecx
;
518 dump
->regs
.edx
= regs
->edx
;
519 dump
->regs
.esi
= regs
->esi
;
520 dump
->regs
.edi
= regs
->edi
;
521 dump
->regs
.ebp
= regs
->ebp
;
522 dump
->regs
.eax
= regs
->eax
;
523 dump
->regs
.ds
= regs
->xds
;
524 dump
->regs
.es
= regs
->xes
;
525 savesegment(fs
,dump
->regs
.fs
);
526 savesegment(gs
,dump
->regs
.gs
);
527 dump
->regs
.orig_eax
= regs
->orig_eax
;
528 dump
->regs
.eip
= regs
->eip
;
529 dump
->regs
.cs
= regs
->xcs
;
530 dump
->regs
.eflags
= regs
->eflags
;
531 dump
->regs
.esp
= regs
->esp
;
532 dump
->regs
.ss
= regs
->xss
;
534 dump
->u_fpvalid
= dump_fpu (regs
, &dump
->i387
);
536 EXPORT_SYMBOL(dump_thread
);
539 * Capture the user space registers if the task is not running (in user space)
541 int dump_task_regs(struct task_struct
*tsk
, elf_gregset_t
*regs
)
543 struct pt_regs ptregs
;
545 ptregs
= *(struct pt_regs
*)
546 ((unsigned long)tsk
->thread_info
+
547 /* see comments in copy_thread() about -8 */
548 THREAD_SIZE
- sizeof(ptregs
) - 8);
549 ptregs
.xcs
&= 0xffff;
550 ptregs
.xds
&= 0xffff;
551 ptregs
.xes
&= 0xffff;
552 ptregs
.xss
&= 0xffff;
554 elf_core_copy_regs(regs
, &ptregs
);
560 handle_io_bitmap(struct thread_struct
*next
, struct tss_struct
*tss
)
562 if (!next
->io_bitmap_ptr
) {
564 * Disable the bitmap via an invalid offset. We still cache
565 * the previous bitmap owner and the IO bitmap contents:
567 tss
->io_bitmap_base
= INVALID_IO_BITMAP_OFFSET
;
570 if (likely(next
== tss
->io_bitmap_owner
)) {
572 * Previous owner of the bitmap (hence the bitmap content)
573 * matches the next task, we dont have to do anything but
574 * to set a valid offset in the TSS:
576 tss
->io_bitmap_base
= IO_BITMAP_OFFSET
;
580 * Lazy TSS's I/O bitmap copy. We set an invalid offset here
581 * and we let the task to get a GPF in case an I/O instruction
582 * is performed. The handler of the GPF will verify that the
583 * faulting task has a valid I/O bitmap and, it true, does the
584 * real copy and restart the instruction. This will save us
585 * redundant copies when the currently switched task does not
586 * perform any I/O during its timeslice.
588 tss
->io_bitmap_base
= INVALID_IO_BITMAP_OFFSET_LAZY
;
592 * This function selects if the context switch from prev to next
593 * has to tweak the TSC disable bit in the cr4.
595 static inline void disable_tsc(struct task_struct
*prev_p
,
596 struct task_struct
*next_p
)
598 struct thread_info
*prev
, *next
;
601 * gcc should eliminate the ->thread_info dereference if
602 * has_secure_computing returns 0 at compile time (SECCOMP=n).
604 prev
= prev_p
->thread_info
;
605 next
= next_p
->thread_info
;
607 if (has_secure_computing(prev
) || has_secure_computing(next
)) {
609 if (has_secure_computing(prev
) &&
610 !has_secure_computing(next
)) {
611 write_cr4(read_cr4() & ~X86_CR4_TSD
);
612 } else if (!has_secure_computing(prev
) &&
613 has_secure_computing(next
))
614 write_cr4(read_cr4() | X86_CR4_TSD
);
619 * switch_to(x,yn) should switch tasks from x to y.
621 * We fsave/fwait so that an exception goes off at the right time
622 * (as a call from the fsave or fwait in effect) rather than to
623 * the wrong process. Lazy FP saving no longer makes any sense
624 * with modern CPU's, and this simplifies a lot of things (SMP
625 * and UP become the same).
627 * NOTE! We used to use the x86 hardware context switching. The
628 * reason for not using it any more becomes apparent when you
629 * try to recover gracefully from saved state that is no longer
630 * valid (stale segment register values in particular). With the
631 * hardware task-switch, there is no way to fix up bad state in
632 * a reasonable manner.
634 * The fact that Intel documents the hardware task-switching to
635 * be slow is a fairly red herring - this code is not noticeably
636 * faster. However, there _is_ some room for improvement here,
637 * so the performance issues may eventually be a valid point.
638 * More important, however, is the fact that this allows us much
641 * The return value (in %eax) will be the "prev" task after
642 * the task-switch, and shows up in ret_from_fork in entry.S,
645 struct task_struct fastcall
* __switch_to(struct task_struct
*prev_p
, struct task_struct
*next_p
)
647 struct thread_struct
*prev
= &prev_p
->thread
,
648 *next
= &next_p
->thread
;
649 int cpu
= smp_processor_id();
650 struct tss_struct
*tss
= &per_cpu(init_tss
, cpu
);
652 /* never put a printk in __switch_to... printk() calls wake_up*() indirectly */
654 __unlazy_fpu(prev_p
);
659 load_esp0(tss
, next
);
662 * Save away %fs and %gs. No need to save %es and %ds, as
663 * those are always kernel segments while inside the kernel.
664 * Doing this before setting the new TLS descriptors avoids
665 * the situation where we temporarily have non-reloadable
666 * segments in %fs and %gs. This could be an issue if the
667 * NMI handler ever used %fs or %gs (it does not today), or
668 * if the kernel is running inside of a hypervisor layer.
670 savesegment(fs
, prev
->fs
);
671 savesegment(gs
, prev
->gs
);
674 * Load the per-thread Thread-Local Storage descriptor.
679 * Restore %fs and %gs if needed.
681 * Glibc normally makes %fs be zero, and %gs is one of
684 if (unlikely(prev
->fs
| next
->fs
))
685 loadsegment(fs
, next
->fs
);
687 if (prev
->gs
| next
->gs
)
688 loadsegment(gs
, next
->gs
);
691 * Restore IOPL if needed.
693 if (unlikely(prev
->iopl
!= next
->iopl
))
694 set_iopl_mask(next
->iopl
);
697 * Now maybe reload the debug registers
699 if (unlikely(next
->debugreg
[7])) {
700 set_debugreg(next
->debugreg
[0], 0);
701 set_debugreg(next
->debugreg
[1], 1);
702 set_debugreg(next
->debugreg
[2], 2);
703 set_debugreg(next
->debugreg
[3], 3);
705 set_debugreg(next
->debugreg
[6], 6);
706 set_debugreg(next
->debugreg
[7], 7);
709 if (unlikely(prev
->io_bitmap_ptr
|| next
->io_bitmap_ptr
))
710 handle_io_bitmap(next
, tss
);
712 disable_tsc(prev_p
, next_p
);
717 asmlinkage
int sys_fork(struct pt_regs regs
)
719 return do_fork(SIGCHLD
, regs
.esp
, ®s
, 0, NULL
, NULL
);
722 asmlinkage
int sys_clone(struct pt_regs regs
)
724 unsigned long clone_flags
;
726 int __user
*parent_tidptr
, *child_tidptr
;
728 clone_flags
= regs
.ebx
;
730 parent_tidptr
= (int __user
*)regs
.edx
;
731 child_tidptr
= (int __user
*)regs
.edi
;
734 return do_fork(clone_flags
, newsp
, ®s
, 0, parent_tidptr
, child_tidptr
);
738 * This is trivial, and on the face of it looks like it
739 * could equally well be done in user mode.
741 * Not so, for quite unobvious reasons - register pressure.
742 * In user mode vfork() cannot have a stack frame, and if
743 * done by calling the "clone()" system call directly, you
744 * do not have enough call-clobbered registers to hold all
745 * the information you need.
747 asmlinkage
int sys_vfork(struct pt_regs regs
)
749 return do_fork(CLONE_VFORK
| CLONE_VM
| SIGCHLD
, regs
.esp
, ®s
, 0, NULL
, NULL
);
753 * sys_execve() executes a new program.
755 asmlinkage
int sys_execve(struct pt_regs regs
)
760 filename
= getname((char __user
*) regs
.ebx
);
761 error
= PTR_ERR(filename
);
762 if (IS_ERR(filename
))
764 error
= do_execve(filename
,
765 (char __user
* __user
*) regs
.ecx
,
766 (char __user
* __user
*) regs
.edx
,
770 current
->ptrace
&= ~PT_DTRACE
;
771 task_unlock(current
);
772 /* Make sure we don't return using sysenter.. */
773 set_thread_flag(TIF_IRET
);
780 #define top_esp (THREAD_SIZE - sizeof(unsigned long))
781 #define top_ebp (THREAD_SIZE - 2*sizeof(unsigned long))
783 unsigned long get_wchan(struct task_struct
*p
)
785 unsigned long ebp
, esp
, eip
;
786 unsigned long stack_page
;
788 if (!p
|| p
== current
|| p
->state
== TASK_RUNNING
)
790 stack_page
= (unsigned long)p
->thread_info
;
792 if (!stack_page
|| esp
< stack_page
|| esp
> top_esp
+stack_page
)
794 /* include/asm-i386/system.h:switch_to() pushes ebp last. */
795 ebp
= *(unsigned long *) esp
;
797 if (ebp
< stack_page
|| ebp
> top_ebp
+stack_page
)
799 eip
= *(unsigned long *) (ebp
+4);
800 if (!in_sched_functions(eip
))
802 ebp
= *(unsigned long *) ebp
;
803 } while (count
++ < 16);
806 EXPORT_SYMBOL(get_wchan
);
809 * sys_alloc_thread_area: get a yet unused TLS descriptor index.
811 static int get_free_idx(void)
813 struct thread_struct
*t
= ¤t
->thread
;
816 for (idx
= 0; idx
< GDT_ENTRY_TLS_ENTRIES
; idx
++)
817 if (desc_empty(t
->tls_array
+ idx
))
818 return idx
+ GDT_ENTRY_TLS_MIN
;
823 * Set a given TLS descriptor:
825 asmlinkage
int sys_set_thread_area(struct user_desc __user
*u_info
)
827 struct thread_struct
*t
= ¤t
->thread
;
828 struct user_desc info
;
829 struct desc_struct
*desc
;
832 if (copy_from_user(&info
, u_info
, sizeof(info
)))
834 idx
= info
.entry_number
;
837 * index -1 means the kernel should try to find and
838 * allocate an empty descriptor:
841 idx
= get_free_idx();
844 if (put_user(idx
, &u_info
->entry_number
))
848 if (idx
< GDT_ENTRY_TLS_MIN
|| idx
> GDT_ENTRY_TLS_MAX
)
851 desc
= t
->tls_array
+ idx
- GDT_ENTRY_TLS_MIN
;
854 * We must not get preempted while modifying the TLS.
858 if (LDT_empty(&info
)) {
862 desc
->a
= LDT_entry_a(&info
);
863 desc
->b
= LDT_entry_b(&info
);
873 * Get the current Thread-Local Storage area:
876 #define GET_BASE(desc) ( \
877 (((desc)->a >> 16) & 0x0000ffff) | \
878 (((desc)->b << 16) & 0x00ff0000) | \
879 ( (desc)->b & 0xff000000) )
881 #define GET_LIMIT(desc) ( \
882 ((desc)->a & 0x0ffff) | \
883 ((desc)->b & 0xf0000) )
885 #define GET_32BIT(desc) (((desc)->b >> 22) & 1)
886 #define GET_CONTENTS(desc) (((desc)->b >> 10) & 3)
887 #define GET_WRITABLE(desc) (((desc)->b >> 9) & 1)
888 #define GET_LIMIT_PAGES(desc) (((desc)->b >> 23) & 1)
889 #define GET_PRESENT(desc) (((desc)->b >> 15) & 1)
890 #define GET_USEABLE(desc) (((desc)->b >> 20) & 1)
892 asmlinkage
int sys_get_thread_area(struct user_desc __user
*u_info
)
894 struct user_desc info
;
895 struct desc_struct
*desc
;
898 if (get_user(idx
, &u_info
->entry_number
))
900 if (idx
< GDT_ENTRY_TLS_MIN
|| idx
> GDT_ENTRY_TLS_MAX
)
903 memset(&info
, 0, sizeof(info
));
905 desc
= current
->thread
.tls_array
+ idx
- GDT_ENTRY_TLS_MIN
;
907 info
.entry_number
= idx
;
908 info
.base_addr
= GET_BASE(desc
);
909 info
.limit
= GET_LIMIT(desc
);
910 info
.seg_32bit
= GET_32BIT(desc
);
911 info
.contents
= GET_CONTENTS(desc
);
912 info
.read_exec_only
= !GET_WRITABLE(desc
);
913 info
.limit_in_pages
= GET_LIMIT_PAGES(desc
);
914 info
.seg_not_present
= !GET_PRESENT(desc
);
915 info
.useable
= GET_USEABLE(desc
);
917 if (copy_to_user(u_info
, &info
, sizeof(info
)))
922 unsigned long arch_align_stack(unsigned long sp
)
924 if (randomize_va_space
)
925 sp
-= get_random_int() % 8192;