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/stddef.h>
25 #include <linux/slab.h>
26 #include <linux/vmalloc.h>
27 #include <linux/user.h>
28 #include <linux/a.out.h>
29 #include <linux/interrupt.h>
30 #include <linux/utsname.h>
31 #include <linux/delay.h>
32 #include <linux/reboot.h>
33 #include <linux/init.h>
34 #include <linux/mc146818rtc.h>
35 #include <linux/module.h>
36 #include <linux/kallsyms.h>
37 #include <linux/ptrace.h>
38 #include <linux/random.h>
39 #include <linux/personality.h>
40 #include <linux/tick.h>
41 #include <linux/percpu.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
);
68 DEFINE_PER_CPU(struct task_struct
*, current_task
) = &init_task
;
69 EXPORT_PER_CPU_SYMBOL(current_task
);
71 DEFINE_PER_CPU(int, cpu_number
);
72 EXPORT_PER_CPU_SYMBOL(cpu_number
);
75 * Return saved PC of a blocked thread.
77 unsigned long thread_saved_pc(struct task_struct
*tsk
)
79 return ((unsigned long *)tsk
->thread
.esp
)[3];
83 * Powermanagement idle function, if any..
85 void (*pm_idle
)(void);
86 EXPORT_SYMBOL(pm_idle
);
87 static DEFINE_PER_CPU(unsigned int, cpu_idle_state
);
89 void disable_hlt(void)
94 EXPORT_SYMBOL(disable_hlt
);
101 EXPORT_SYMBOL(enable_hlt
);
104 * We use this if we don't have any better
107 void default_idle(void)
109 if (!hlt_counter
&& boot_cpu_data
.hlt_works_ok
) {
110 current_thread_info()->status
&= ~TS_POLLING
;
112 * TS_POLLING-cleared state must be visible before we
119 safe_halt(); /* enables interrupts racelessly */
122 current_thread_info()->status
|= TS_POLLING
;
124 /* loop is done by the caller */
128 #ifdef CONFIG_APM_MODULE
129 EXPORT_SYMBOL(default_idle
);
133 * On SMP it's slightly faster (but much more power-consuming!)
134 * to poll the ->work.need_resched flag instead of waiting for the
135 * cross-CPU IPI to arrive. Use this option with caution.
137 static void poll_idle (void)
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 current_thread_info()->status
|= TS_POLLING
;
180 /* endless idle loop with no priority at all */
182 tick_nohz_stop_sched_tick();
183 while (!need_resched()) {
186 if (__get_cpu_var(cpu_idle_state
))
187 __get_cpu_var(cpu_idle_state
) = 0;
195 if (cpu_is_offline(cpu
))
198 __get_cpu_var(irq_stat
).idle_timestamp
= jiffies
;
201 tick_nohz_restart_sched_tick();
202 preempt_enable_no_resched();
208 void cpu_idle_wait(void)
210 unsigned int cpu
, this_cpu
= get_cpu();
211 cpumask_t map
, tmp
= current
->cpus_allowed
;
213 set_cpus_allowed(current
, cpumask_of_cpu(this_cpu
));
217 for_each_online_cpu(cpu
) {
218 per_cpu(cpu_idle_state
, cpu
) = 1;
222 __get_cpu_var(cpu_idle_state
) = 0;
227 for_each_online_cpu(cpu
) {
228 if (cpu_isset(cpu
, map
) && !per_cpu(cpu_idle_state
, cpu
))
231 cpus_and(map
, map
, cpu_online_map
);
232 } while (!cpus_empty(map
));
234 set_cpus_allowed(current
, tmp
);
236 EXPORT_SYMBOL_GPL(cpu_idle_wait
);
239 * This uses new MONITOR/MWAIT instructions on P4 processors with PNI,
240 * which can obviate IPI to trigger checking of need_resched.
241 * We execute MONITOR against need_resched and enter optimized wait state
242 * through MWAIT. Whenever someone changes need_resched, we would be woken
243 * up from MWAIT (without an IPI).
245 * New with Core Duo processors, MWAIT can take some hints based on CPU
248 void mwait_idle_with_hints(unsigned long eax
, unsigned long ecx
)
250 if (!need_resched()) {
251 __monitor((void *)¤t_thread_info()->flags
, 0, 0);
258 /* Default MONITOR/MWAIT with no hints, used for default C1 state */
259 static void mwait_idle(void)
262 mwait_idle_with_hints(0, 0);
265 void __devinit
select_idle_routine(const struct cpuinfo_x86
*c
)
267 if (cpu_has(c
, X86_FEATURE_MWAIT
)) {
268 printk("monitor/mwait feature present.\n");
270 * Skip, if setup has overridden idle.
271 * One CPU supports mwait => All CPUs supports mwait
274 printk("using mwait in idle threads.\n");
275 pm_idle
= mwait_idle
;
280 static int __init
idle_setup(char *str
)
282 if (!strcmp(str
, "poll")) {
283 printk("using polling idle threads.\n");
285 #ifdef CONFIG_X86_SMP
286 if (smp_num_siblings
> 1)
287 printk("WARNING: polling idle and HT enabled, performance may degrade.\n");
289 } else if (!strcmp(str
, "mwait"))
294 boot_option_idle_override
= 1;
297 early_param("idle", idle_setup
);
299 void show_regs(struct pt_regs
* regs
)
301 unsigned long cr0
= 0L, cr2
= 0L, cr3
= 0L, cr4
= 0L;
304 printk("Pid: %d, comm: %20s\n", current
->pid
, current
->comm
);
305 printk("EIP: %04x:[<%08lx>] CPU: %d\n",0xffff & regs
->xcs
,regs
->eip
, smp_processor_id());
306 print_symbol("EIP is at %s\n", regs
->eip
);
308 if (user_mode_vm(regs
))
309 printk(" ESP: %04x:%08lx",0xffff & regs
->xss
,regs
->esp
);
310 printk(" EFLAGS: %08lx %s (%s %.*s)\n",
311 regs
->eflags
, print_tainted(), init_utsname()->release
,
312 (int)strcspn(init_utsname()->version
, " "),
313 init_utsname()->version
);
314 printk("EAX: %08lx EBX: %08lx ECX: %08lx EDX: %08lx\n",
315 regs
->eax
,regs
->ebx
,regs
->ecx
,regs
->edx
);
316 printk("ESI: %08lx EDI: %08lx EBP: %08lx",
317 regs
->esi
, regs
->edi
, regs
->ebp
);
318 printk(" DS: %04x ES: %04x FS: %04x\n",
319 0xffff & regs
->xds
,0xffff & regs
->xes
, 0xffff & regs
->xfs
);
324 cr4
= read_cr4_safe();
325 printk("CR0: %08lx CR2: %08lx CR3: %08lx CR4: %08lx\n", cr0
, cr2
, cr3
, cr4
);
326 show_trace(NULL
, regs
, ®s
->esp
);
330 * This gets run with %ebx containing the
331 * function to call, and %edx containing
334 extern void kernel_thread_helper(void);
337 * Create a kernel thread
339 int kernel_thread(int (*fn
)(void *), void * arg
, unsigned long flags
)
343 memset(®s
, 0, sizeof(regs
));
345 regs
.ebx
= (unsigned long) fn
;
346 regs
.edx
= (unsigned long) arg
;
348 regs
.xds
= __USER_DS
;
349 regs
.xes
= __USER_DS
;
350 regs
.xfs
= __KERNEL_PERCPU
;
352 regs
.eip
= (unsigned long) kernel_thread_helper
;
353 regs
.xcs
= __KERNEL_CS
| get_kernel_rpl();
354 regs
.eflags
= X86_EFLAGS_IF
| X86_EFLAGS_SF
| X86_EFLAGS_PF
| 0x2;
356 /* Ok, create the new process.. */
357 return do_fork(flags
| CLONE_VM
| CLONE_UNTRACED
, 0, ®s
, 0, NULL
, NULL
);
359 EXPORT_SYMBOL(kernel_thread
);
362 * Free current thread data structures etc..
364 void exit_thread(void)
366 /* The process may have allocated an io port bitmap... nuke it. */
367 if (unlikely(test_thread_flag(TIF_IO_BITMAP
))) {
368 struct task_struct
*tsk
= current
;
369 struct thread_struct
*t
= &tsk
->thread
;
371 struct tss_struct
*tss
= &per_cpu(init_tss
, cpu
);
373 kfree(t
->io_bitmap_ptr
);
374 t
->io_bitmap_ptr
= NULL
;
375 clear_thread_flag(TIF_IO_BITMAP
);
377 * Careful, clear this in the TSS too:
379 memset(tss
->io_bitmap
, 0xff, tss
->io_bitmap_max
);
380 t
->io_bitmap_max
= 0;
381 tss
->io_bitmap_owner
= NULL
;
382 tss
->io_bitmap_max
= 0;
383 tss
->x86_tss
.io_bitmap_base
= INVALID_IO_BITMAP_OFFSET
;
388 void flush_thread(void)
390 struct task_struct
*tsk
= current
;
392 memset(tsk
->thread
.debugreg
, 0, sizeof(unsigned long)*8);
393 memset(tsk
->thread
.tls_array
, 0, sizeof(tsk
->thread
.tls_array
));
394 clear_tsk_thread_flag(tsk
, TIF_DEBUG
);
396 * Forget coprocessor state..
402 void release_thread(struct task_struct
*dead_task
)
404 BUG_ON(dead_task
->mm
);
405 release_vm86_irqs(dead_task
);
409 * This gets called before we allocate a new thread and copy
410 * the current task into it.
412 void prepare_to_copy(struct task_struct
*tsk
)
417 int copy_thread(int nr
, unsigned long clone_flags
, unsigned long esp
,
418 unsigned long unused
,
419 struct task_struct
* p
, struct pt_regs
* regs
)
421 struct pt_regs
* childregs
;
422 struct task_struct
*tsk
;
425 childregs
= task_pt_regs(p
);
428 childregs
->esp
= esp
;
430 p
->thread
.esp
= (unsigned long) childregs
;
431 p
->thread
.esp0
= (unsigned long) (childregs
+1);
433 p
->thread
.eip
= (unsigned long) ret_from_fork
;
435 savesegment(gs
,p
->thread
.gs
);
438 if (unlikely(test_tsk_thread_flag(tsk
, TIF_IO_BITMAP
))) {
439 p
->thread
.io_bitmap_ptr
= kmemdup(tsk
->thread
.io_bitmap_ptr
,
440 IO_BITMAP_BYTES
, GFP_KERNEL
);
441 if (!p
->thread
.io_bitmap_ptr
) {
442 p
->thread
.io_bitmap_max
= 0;
445 set_tsk_thread_flag(p
, TIF_IO_BITMAP
);
449 * Set a new TLS for the child thread?
451 if (clone_flags
& CLONE_SETTLS
) {
452 struct desc_struct
*desc
;
453 struct user_desc info
;
457 if (copy_from_user(&info
, (void __user
*)childregs
->esi
, sizeof(info
)))
460 if (LDT_empty(&info
))
463 idx
= info
.entry_number
;
464 if (idx
< GDT_ENTRY_TLS_MIN
|| idx
> GDT_ENTRY_TLS_MAX
)
467 desc
= p
->thread
.tls_array
+ idx
- GDT_ENTRY_TLS_MIN
;
468 desc
->a
= LDT_entry_a(&info
);
469 desc
->b
= LDT_entry_b(&info
);
474 if (err
&& p
->thread
.io_bitmap_ptr
) {
475 kfree(p
->thread
.io_bitmap_ptr
);
476 p
->thread
.io_bitmap_max
= 0;
482 * fill in the user structure for a core dump..
484 void dump_thread(struct pt_regs
* regs
, struct user
* dump
)
488 /* changed the size calculations - should hopefully work better. lbt */
489 dump
->magic
= CMAGIC
;
490 dump
->start_code
= 0;
491 dump
->start_stack
= regs
->esp
& ~(PAGE_SIZE
- 1);
492 dump
->u_tsize
= ((unsigned long) current
->mm
->end_code
) >> PAGE_SHIFT
;
493 dump
->u_dsize
= ((unsigned long) (current
->mm
->brk
+ (PAGE_SIZE
-1))) >> PAGE_SHIFT
;
494 dump
->u_dsize
-= dump
->u_tsize
;
496 for (i
= 0; i
< 8; i
++)
497 dump
->u_debugreg
[i
] = current
->thread
.debugreg
[i
];
499 if (dump
->start_stack
< TASK_SIZE
)
500 dump
->u_ssize
= ((unsigned long) (TASK_SIZE
- dump
->start_stack
)) >> PAGE_SHIFT
;
502 dump
->regs
.ebx
= regs
->ebx
;
503 dump
->regs
.ecx
= regs
->ecx
;
504 dump
->regs
.edx
= regs
->edx
;
505 dump
->regs
.esi
= regs
->esi
;
506 dump
->regs
.edi
= regs
->edi
;
507 dump
->regs
.ebp
= regs
->ebp
;
508 dump
->regs
.eax
= regs
->eax
;
509 dump
->regs
.ds
= regs
->xds
;
510 dump
->regs
.es
= regs
->xes
;
511 dump
->regs
.fs
= regs
->xfs
;
512 savesegment(gs
,dump
->regs
.gs
);
513 dump
->regs
.orig_eax
= regs
->orig_eax
;
514 dump
->regs
.eip
= regs
->eip
;
515 dump
->regs
.cs
= regs
->xcs
;
516 dump
->regs
.eflags
= regs
->eflags
;
517 dump
->regs
.esp
= regs
->esp
;
518 dump
->regs
.ss
= regs
->xss
;
520 dump
->u_fpvalid
= dump_fpu (regs
, &dump
->i387
);
522 EXPORT_SYMBOL(dump_thread
);
525 * Capture the user space registers if the task is not running (in user space)
527 int dump_task_regs(struct task_struct
*tsk
, elf_gregset_t
*regs
)
529 struct pt_regs ptregs
= *task_pt_regs(tsk
);
530 ptregs
.xcs
&= 0xffff;
531 ptregs
.xds
&= 0xffff;
532 ptregs
.xes
&= 0xffff;
533 ptregs
.xss
&= 0xffff;
535 elf_core_copy_regs(regs
, &ptregs
);
540 static noinline
void __switch_to_xtra(struct task_struct
*next_p
,
541 struct tss_struct
*tss
)
543 struct thread_struct
*next
;
545 next
= &next_p
->thread
;
547 if (test_tsk_thread_flag(next_p
, TIF_DEBUG
)) {
548 set_debugreg(next
->debugreg
[0], 0);
549 set_debugreg(next
->debugreg
[1], 1);
550 set_debugreg(next
->debugreg
[2], 2);
551 set_debugreg(next
->debugreg
[3], 3);
553 set_debugreg(next
->debugreg
[6], 6);
554 set_debugreg(next
->debugreg
[7], 7);
557 if (!test_tsk_thread_flag(next_p
, TIF_IO_BITMAP
)) {
559 * Disable the bitmap via an invalid offset. We still cache
560 * the previous bitmap owner and the IO bitmap contents:
562 tss
->x86_tss
.io_bitmap_base
= INVALID_IO_BITMAP_OFFSET
;
566 if (likely(next
== tss
->io_bitmap_owner
)) {
568 * Previous owner of the bitmap (hence the bitmap content)
569 * matches the next task, we dont have to do anything but
570 * to set a valid offset in the TSS:
572 tss
->x86_tss
.io_bitmap_base
= IO_BITMAP_OFFSET
;
576 * Lazy TSS's I/O bitmap copy. We set an invalid offset here
577 * and we let the task to get a GPF in case an I/O instruction
578 * is performed. The handler of the GPF will verify that the
579 * faulting task has a valid I/O bitmap and, it true, does the
580 * real copy and restart the instruction. This will save us
581 * redundant copies when the currently switched task does not
582 * perform any I/O during its timeslice.
584 tss
->x86_tss
.io_bitmap_base
= INVALID_IO_BITMAP_OFFSET_LAZY
;
588 * This function selects if the context switch from prev to next
589 * has to tweak the TSC disable bit in the cr4.
591 static inline void disable_tsc(struct task_struct
*prev_p
,
592 struct task_struct
*next_p
)
594 struct thread_info
*prev
, *next
;
597 * gcc should eliminate the ->thread_info dereference if
598 * has_secure_computing returns 0 at compile time (SECCOMP=n).
600 prev
= task_thread_info(prev_p
);
601 next
= task_thread_info(next_p
);
603 if (has_secure_computing(prev
) || has_secure_computing(next
)) {
605 if (has_secure_computing(prev
) &&
606 !has_secure_computing(next
)) {
607 write_cr4(read_cr4() & ~X86_CR4_TSD
);
608 } else if (!has_secure_computing(prev
) &&
609 has_secure_computing(next
))
610 write_cr4(read_cr4() | X86_CR4_TSD
);
615 * switch_to(x,yn) should switch tasks from x to y.
617 * We fsave/fwait so that an exception goes off at the right time
618 * (as a call from the fsave or fwait in effect) rather than to
619 * the wrong process. Lazy FP saving no longer makes any sense
620 * with modern CPU's, and this simplifies a lot of things (SMP
621 * and UP become the same).
623 * NOTE! We used to use the x86 hardware context switching. The
624 * reason for not using it any more becomes apparent when you
625 * try to recover gracefully from saved state that is no longer
626 * valid (stale segment register values in particular). With the
627 * hardware task-switch, there is no way to fix up bad state in
628 * a reasonable manner.
630 * The fact that Intel documents the hardware task-switching to
631 * be slow is a fairly red herring - this code is not noticeably
632 * faster. However, there _is_ some room for improvement here,
633 * so the performance issues may eventually be a valid point.
634 * More important, however, is the fact that this allows us much
637 * The return value (in %eax) will be the "prev" task after
638 * the task-switch, and shows up in ret_from_fork in entry.S,
641 struct task_struct fastcall
* __switch_to(struct task_struct
*prev_p
, struct task_struct
*next_p
)
643 struct thread_struct
*prev
= &prev_p
->thread
,
644 *next
= &next_p
->thread
;
645 int cpu
= smp_processor_id();
646 struct tss_struct
*tss
= &per_cpu(init_tss
, cpu
);
648 /* never put a printk in __switch_to... printk() calls wake_up*() indirectly */
650 __unlazy_fpu(prev_p
);
653 /* we're going to use this soon, after a few expensive things */
654 if (next_p
->fpu_counter
> 5)
655 prefetch(&next
->i387
.fxsave
);
660 load_esp0(tss
, next
);
663 * Save away %gs. No need to save %fs, as it was saved on the
664 * stack on entry. No need to save %es and %ds, as those are
665 * always kernel segments while inside the kernel. Doing this
666 * before setting the new TLS descriptors avoids the situation
667 * where we temporarily have non-reloadable segments in %fs
668 * and %gs. This could be an issue if the NMI handler ever
669 * used %fs or %gs (it does not today), or if the kernel is
670 * running inside of a hypervisor layer.
672 savesegment(gs
, prev
->gs
);
675 * Load the per-thread Thread-Local Storage descriptor.
680 * Restore IOPL if needed. In normal use, the flags restore
681 * in the switch assembly will handle this. But if the kernel
682 * is running virtualized at a non-zero CPL, the popf will
683 * not restore flags, so it must be done in a separate step.
685 if (get_kernel_rpl() && unlikely(prev
->iopl
!= next
->iopl
))
686 set_iopl_mask(next
->iopl
);
689 * Now maybe handle debug registers and/or IO bitmaps
691 if (unlikely((task_thread_info(next_p
)->flags
& _TIF_WORK_CTXSW
)
692 || test_tsk_thread_flag(prev_p
, TIF_IO_BITMAP
)))
693 __switch_to_xtra(next_p
, tss
);
695 disable_tsc(prev_p
, next_p
);
698 * Leave lazy mode, flushing any hypercalls made here.
699 * This must be done before restoring TLS segments so
700 * the GDT and LDT are properly updated, and must be
701 * done before math_state_restore, so the TS bit is up
704 arch_leave_lazy_cpu_mode();
706 /* If the task has used fpu the last 5 timeslices, just do a full
707 * restore of the math state immediately to avoid the trap; the
708 * chances of needing FPU soon are obviously high now
710 if (next_p
->fpu_counter
> 5)
711 math_state_restore();
714 * Restore %gs if needed (which is common)
716 if (prev
->gs
| next
->gs
)
717 loadsegment(gs
, next
->gs
);
719 x86_write_percpu(current_task
, next_p
);
724 asmlinkage
int sys_fork(struct pt_regs regs
)
726 return do_fork(SIGCHLD
, regs
.esp
, ®s
, 0, NULL
, NULL
);
729 asmlinkage
int sys_clone(struct pt_regs regs
)
731 unsigned long clone_flags
;
733 int __user
*parent_tidptr
, *child_tidptr
;
735 clone_flags
= regs
.ebx
;
737 parent_tidptr
= (int __user
*)regs
.edx
;
738 child_tidptr
= (int __user
*)regs
.edi
;
741 return do_fork(clone_flags
, newsp
, ®s
, 0, parent_tidptr
, child_tidptr
);
745 * This is trivial, and on the face of it looks like it
746 * could equally well be done in user mode.
748 * Not so, for quite unobvious reasons - register pressure.
749 * In user mode vfork() cannot have a stack frame, and if
750 * done by calling the "clone()" system call directly, you
751 * do not have enough call-clobbered registers to hold all
752 * the information you need.
754 asmlinkage
int sys_vfork(struct pt_regs regs
)
756 return do_fork(CLONE_VFORK
| CLONE_VM
| SIGCHLD
, regs
.esp
, ®s
, 0, NULL
, NULL
);
760 * sys_execve() executes a new program.
762 asmlinkage
int sys_execve(struct pt_regs regs
)
767 filename
= getname((char __user
*) regs
.ebx
);
768 error
= PTR_ERR(filename
);
769 if (IS_ERR(filename
))
771 error
= do_execve(filename
,
772 (char __user
* __user
*) regs
.ecx
,
773 (char __user
* __user
*) regs
.edx
,
777 current
->ptrace
&= ~PT_DTRACE
;
778 task_unlock(current
);
779 /* Make sure we don't return using sysenter.. */
780 set_thread_flag(TIF_IRET
);
787 #define top_esp (THREAD_SIZE - sizeof(unsigned long))
788 #define top_ebp (THREAD_SIZE - 2*sizeof(unsigned long))
790 unsigned long get_wchan(struct task_struct
*p
)
792 unsigned long ebp
, esp
, eip
;
793 unsigned long stack_page
;
795 if (!p
|| p
== current
|| p
->state
== TASK_RUNNING
)
797 stack_page
= (unsigned long)task_stack_page(p
);
799 if (!stack_page
|| esp
< stack_page
|| esp
> top_esp
+stack_page
)
801 /* include/asm-i386/system.h:switch_to() pushes ebp last. */
802 ebp
= *(unsigned long *) esp
;
804 if (ebp
< stack_page
|| ebp
> top_ebp
+stack_page
)
806 eip
= *(unsigned long *) (ebp
+4);
807 if (!in_sched_functions(eip
))
809 ebp
= *(unsigned long *) ebp
;
810 } while (count
++ < 16);
815 * sys_alloc_thread_area: get a yet unused TLS descriptor index.
817 static int get_free_idx(void)
819 struct thread_struct
*t
= ¤t
->thread
;
822 for (idx
= 0; idx
< GDT_ENTRY_TLS_ENTRIES
; idx
++)
823 if (desc_empty(t
->tls_array
+ idx
))
824 return idx
+ GDT_ENTRY_TLS_MIN
;
829 * Set a given TLS descriptor:
831 asmlinkage
int sys_set_thread_area(struct user_desc __user
*u_info
)
833 struct thread_struct
*t
= ¤t
->thread
;
834 struct user_desc info
;
835 struct desc_struct
*desc
;
838 if (copy_from_user(&info
, u_info
, sizeof(info
)))
840 idx
= info
.entry_number
;
843 * index -1 means the kernel should try to find and
844 * allocate an empty descriptor:
847 idx
= get_free_idx();
850 if (put_user(idx
, &u_info
->entry_number
))
854 if (idx
< GDT_ENTRY_TLS_MIN
|| idx
> GDT_ENTRY_TLS_MAX
)
857 desc
= t
->tls_array
+ idx
- GDT_ENTRY_TLS_MIN
;
860 * We must not get preempted while modifying the TLS.
864 if (LDT_empty(&info
)) {
868 desc
->a
= LDT_entry_a(&info
);
869 desc
->b
= LDT_entry_b(&info
);
879 * Get the current Thread-Local Storage area:
882 #define GET_BASE(desc) ( \
883 (((desc)->a >> 16) & 0x0000ffff) | \
884 (((desc)->b << 16) & 0x00ff0000) | \
885 ( (desc)->b & 0xff000000) )
887 #define GET_LIMIT(desc) ( \
888 ((desc)->a & 0x0ffff) | \
889 ((desc)->b & 0xf0000) )
891 #define GET_32BIT(desc) (((desc)->b >> 22) & 1)
892 #define GET_CONTENTS(desc) (((desc)->b >> 10) & 3)
893 #define GET_WRITABLE(desc) (((desc)->b >> 9) & 1)
894 #define GET_LIMIT_PAGES(desc) (((desc)->b >> 23) & 1)
895 #define GET_PRESENT(desc) (((desc)->b >> 15) & 1)
896 #define GET_USEABLE(desc) (((desc)->b >> 20) & 1)
898 asmlinkage
int sys_get_thread_area(struct user_desc __user
*u_info
)
900 struct user_desc info
;
901 struct desc_struct
*desc
;
904 if (get_user(idx
, &u_info
->entry_number
))
906 if (idx
< GDT_ENTRY_TLS_MIN
|| idx
> GDT_ENTRY_TLS_MAX
)
909 memset(&info
, 0, sizeof(info
));
911 desc
= current
->thread
.tls_array
+ idx
- GDT_ENTRY_TLS_MIN
;
913 info
.entry_number
= idx
;
914 info
.base_addr
= GET_BASE(desc
);
915 info
.limit
= GET_LIMIT(desc
);
916 info
.seg_32bit
= GET_32BIT(desc
);
917 info
.contents
= GET_CONTENTS(desc
);
918 info
.read_exec_only
= !GET_WRITABLE(desc
);
919 info
.limit_in_pages
= GET_LIMIT_PAGES(desc
);
920 info
.seg_not_present
= !GET_PRESENT(desc
);
921 info
.useable
= GET_USEABLE(desc
);
923 if (copy_to_user(u_info
, &info
, sizeof(info
)))
928 unsigned long arch_align_stack(unsigned long sp
)
930 if (!(current
->personality
& ADDR_NO_RANDOMIZE
) && randomize_va_space
)
931 sp
-= get_random_int() % 8192;