1 /*
2 * linux/arch/i386/kernel/process.c
3 *
4 * Copyright (C) 1995 Linus Torvalds
5 *
6 * Pentium III FXSR, SSE support
7 * Gareth Hughes <gareth@valinux.com>, May 2000
8 */
9
10 /*
11 * This file handles the architecture-dependent parts of process handling..
12 */
13
14 #include <stdarg.h>
15
16 #include <linux/errno.h>
17 #include <linux/sched.h>
18 #include <linux/fs.h>
19 #include <linux/kernel.h>
20 #include <linux/mm.h>
21 #include <linux/elfcore.h>
22 #include <linux/smp.h>
23 #include <linux/smp_lock.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/config.h>
31 #include <linux/utsname.h>
32 #include <linux/delay.h>
33 #include <linux/reboot.h>
34 #include <linux/init.h>
35 #include <linux/mc146818rtc.h>
36 #include <linux/module.h>
37 #include <linux/kallsyms.h>
38 #include <linux/ptrace.h>
39
40 #include <asm/uaccess.h>
41 #include <asm/pgtable.h>
42 #include <asm/system.h>
43 #include <asm/io.h>
44 #include <asm/ldt.h>
45 #include <asm/processor.h>
46 #include <asm/i387.h>
47 #include <asm/irq.h>
48 #include <asm/desc.h>
49 #ifdef CONFIG_MATH_EMULATION
50 #include <asm/math_emu.h>
51 #endif
52
53 #include <linux/irq.h>
54 #include <linux/err.h>
55
56 asmlinkage void ret_from_fork(void) __asm__("ret_from_fork");
57
58 int hlt_counter;
59
60 unsigned long boot_option_idle_override = 0;
61 EXPORT_SYMBOL(boot_option_idle_override);
62
63 /*
64 * Return saved PC of a blocked thread.
65 */
66 unsigned long thread_saved_pc(struct task_struct *tsk)
67 {
68 return ((unsigned long *)tsk->thread.esp)[3];
69 }
70
71 /*
72 * Powermanagement idle function, if any..
73 */
74 void (*pm_idle)(void);
75 static cpumask_t cpu_idle_map;
76
77 void disable_hlt(void)
78 {
79 hlt_counter++;
80 }
81
82 EXPORT_SYMBOL(disable_hlt);
83
84 void enable_hlt(void)
85 {
86 hlt_counter--;
87 }
88
89 EXPORT_SYMBOL(enable_hlt);
90
91 /*
92 * We use this if we don't have any better
93 * idle routine..
94 */
95 void default_idle(void)
96 {
97 if (!hlt_counter && boot_cpu_data.hlt_works_ok) {
98 local_irq_disable();
99 if (!need_resched())
100 safe_halt();
101 else
102 local_irq_enable();
103 } else {
104 cpu_relax();
105 }
106 }
107
108 /*
109 * On SMP it's slightly faster (but much more power-consuming!)
110 * to poll the ->work.need_resched flag instead of waiting for the
111 * cross-CPU IPI to arrive. Use this option with caution.
112 */
113 static void poll_idle (void)
114 {
115 int oldval;
116
117 local_irq_enable();
118
119 /*
120 * Deal with another CPU just having chosen a thread to
121 * run here:
122 */
123 oldval = test_and_clear_thread_flag(TIF_NEED_RESCHED);
124
125 if (!oldval) {
126 set_thread_flag(TIF_POLLING_NRFLAG);
127 asm volatile(
128 "2:"
129 "testl %0, %1;"
130 "rep; nop;"
131 "je 2b;"
132 : : "i"(_TIF_NEED_RESCHED), "m" (current_thread_info()->flags));
133
134 clear_thread_flag(TIF_POLLING_NRFLAG);
135 } else {
136 set_need_resched();
137 }
138 }
139
140 /*
141 * The idle thread. There's no useful work to be
142 * done, so just try to conserve power and have a
143 * low exit latency (ie sit in a loop waiting for
144 * somebody to say that they'd like to reschedule)
145 */
146 void cpu_idle (void)
147 {
148 int cpu = _smp_processor_id();
149
150 /* endless idle loop with no priority at all */
151 while (1) {
152 while (!need_resched()) {
153 void (*idle)(void);
154
155 if (cpu_isset(cpu, cpu_idle_map))
156 cpu_clear(cpu, cpu_idle_map);
157 rmb();
158 idle = pm_idle;
159
160 if (!idle)
161 idle = default_idle;
162
163 irq_stat[cpu].idle_timestamp = jiffies;
164 idle();
165 }
166 schedule();
167 }
168 }
169
170 void cpu_idle_wait(void)
171 {
172 int cpu;
173 cpumask_t map;
174
175 for_each_online_cpu(cpu)
176 cpu_set(cpu, cpu_idle_map);
177
178 wmb();
179 do {
180 ssleep(1);
181 cpus_and(map, cpu_idle_map, cpu_online_map);
182 } while (!cpus_empty(map));
183 }
184 EXPORT_SYMBOL_GPL(cpu_idle_wait);
185
186 /*
187 * This uses new MONITOR/MWAIT instructions on P4 processors with PNI,
188 * which can obviate IPI to trigger checking of need_resched.
189 * We execute MONITOR against need_resched and enter optimized wait state
190 * through MWAIT. Whenever someone changes need_resched, we would be woken
191 * up from MWAIT (without an IPI).
192 */
193 static void mwait_idle(void)
194 {
195 local_irq_enable();
196
197 if (!need_resched()) {
198 set_thread_flag(TIF_POLLING_NRFLAG);
199 do {
200 __monitor((void *)¤t_thread_info()->flags, 0, 0);
201 if (need_resched())
202 break;
203 __mwait(0, 0);
204 } while (!need_resched());
205 clear_thread_flag(TIF_POLLING_NRFLAG);
206 }
207 }
208
209 void __init select_idle_routine(const struct cpuinfo_x86 *c)
210 {
211 if (cpu_has(c, X86_FEATURE_MWAIT)) {
212 printk("monitor/mwait feature present.\n");
213 /*
214 * Skip, if setup has overridden idle.
215 * One CPU supports mwait => All CPUs supports mwait
216 */
217 if (!pm_idle) {
218 printk("using mwait in idle threads.\n");
219 pm_idle = mwait_idle;
220 }
221 }
222 }
223
224 static int __init idle_setup (char *str)
225 {
226 if (!strncmp(str, "poll", 4)) {
227 printk("using polling idle threads.\n");
228 pm_idle = poll_idle;
229 #ifdef CONFIG_X86_SMP
230 if (smp_num_siblings > 1)
231 printk("WARNING: polling idle and HT enabled, performance may degrade.\n");
232 #endif
233 } else if (!strncmp(str, "halt", 4)) {
234 printk("using halt in idle threads.\n");
235 pm_idle = default_idle;
236 }
237
238 boot_option_idle_override = 1;
239 return 1;
240 }
241
242 __setup("idle=", idle_setup);
243
244 void show_regs(struct pt_regs * regs)
245 {
246 unsigned long cr0 = 0L, cr2 = 0L, cr3 = 0L, cr4 = 0L;
247
248 printk("\n");
249 printk("Pid: %d, comm: %20s\n", current->pid, current->comm);
250 printk("EIP: %04x:[<%08lx>] CPU: %d\n",0xffff & regs->xcs,regs->eip, smp_processor_id());
251 print_symbol("EIP is at %s\n", regs->eip);
252
253 if (regs->xcs & 3)
254 printk(" ESP: %04x:%08lx",0xffff & regs->xss,regs->esp);
255 printk(" EFLAGS: %08lx %s (%s)\n",
256 regs->eflags, print_tainted(), system_utsname.release);
257 printk("EAX: %08lx EBX: %08lx ECX: %08lx EDX: %08lx\n",
258 regs->eax,regs->ebx,regs->ecx,regs->edx);
259 printk("ESI: %08lx EDI: %08lx EBP: %08lx",
260 regs->esi, regs->edi, regs->ebp);
261 printk(" DS: %04x ES: %04x\n",
262 0xffff & regs->xds,0xffff & regs->xes);
263
264 __asm__("movl %%cr0, %0": "=r" (cr0));
265 __asm__("movl %%cr2, %0": "=r" (cr2));
266 __asm__("movl %%cr3, %0": "=r" (cr3));
267 /* This could fault if %cr4 does not exist */
268 __asm__("1: movl %%cr4, %0 \n"
269 "2: \n"
270 ".section __ex_table,\"a\" \n"
271 ".long 1b,2b \n"
272 ".previous \n"
273 : "=r" (cr4): "" (0));
274 printk("CR0: %08lx CR2: %08lx CR3: %08lx CR4: %08lx\n", cr0, cr2, cr3, cr4);
275 show_trace(NULL, ®s->esp);
276 }
277
278 /*
279 * This gets run with %ebx containing the
280 * function to call, and %edx containing
281 * the "args".
282 */
283 extern void kernel_thread_helper(void);
284 __asm__(".section .text\n"
285 ".align 4\n"
286 "kernel_thread_helper:\n\t"
287 "movl %edx,%eax\n\t"
288 "pushl %edx\n\t"
289 "call *%ebx\n\t"
290 "pushl %eax\n\t"
291 "call do_exit\n"
292 ".previous");
293
294 /*
295 * Create a kernel thread
296 */
297 int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
298 {
299 struct pt_regs regs;
300
301 memset(®s, 0, sizeof(regs));
302
303 regs.ebx = (unsigned long) fn;
304 regs.edx = (unsigned long) arg;
305
306 regs.xds = __USER_DS;
307 regs.xes = __USER_DS;
308 regs.orig_eax = -1;
309 regs.eip = (unsigned long) kernel_thread_helper;
310 regs.xcs = __KERNEL_CS;
311 regs.eflags = X86_EFLAGS_IF | X86_EFLAGS_SF | X86_EFLAGS_PF | 0x2;
312
313 /* Ok, create the new process.. */
314 return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, ®s, 0, NULL, NULL);
315 }
316
317 /*
318 * Free current thread data structures etc..
319 */
320 void exit_thread(void)
321 {
322 struct task_struct *tsk = current;
323 struct thread_struct *t = &tsk->thread;
324
325 /* The process may have allocated an io port bitmap... nuke it. */
326 if (unlikely(NULL != t->io_bitmap_ptr)) {
327 int cpu = get_cpu();
328 struct tss_struct *tss = &per_cpu(init_tss, cpu);
329
330 kfree(t->io_bitmap_ptr);
331 t->io_bitmap_ptr = NULL;
332 /*
333 * Careful, clear this in the TSS too:
334 */
335 memset(tss->io_bitmap, 0xff, tss->io_bitmap_max);
336 t->io_bitmap_max = 0;
337 tss->io_bitmap_owner = NULL;
338 tss->io_bitmap_max = 0;
339 tss->io_bitmap_base = INVALID_IO_BITMAP_OFFSET;
340 put_cpu();
341 }
342 }
343
344 void flush_thread(void)
345 {
346 struct task_struct *tsk = current;
347
348 memset(tsk->thread.debugreg, 0, sizeof(unsigned long)*8);
349 memset(tsk->thread.tls_array, 0, sizeof(tsk->thread.tls_array));
350 /*
351 * Forget coprocessor state..
352 */
353 clear_fpu(tsk);
354 clear_used_math();
355 }
356
357 void release_thread(struct task_struct *dead_task)
358 {
359 if (dead_task->mm) {
360 // temporary debugging check
361 if (dead_task->mm->context.size) {
362 printk("WARNING: dead process %8s still has LDT? <%p/%d>\n",
363 dead_task->comm,
364 dead_task->mm->context.ldt,
365 dead_task->mm->context.size);
366 BUG();
367 }
368 }
369
370 release_vm86_irqs(dead_task);
371 }
372
373 /*
374 * This gets called before we allocate a new thread and copy
375 * the current task into it.
376 */
377 void prepare_to_copy(struct task_struct *tsk)
378 {
379 unlazy_fpu(tsk);
380 }
381
382 int copy_thread(int nr, unsigned long clone_flags, unsigned long esp,
383 unsigned long unused,
384 struct task_struct * p, struct pt_regs * regs)
385 {
386 struct pt_regs * childregs;
387 struct task_struct *tsk;
388 int err;
389
390 childregs = ((struct pt_regs *) (THREAD_SIZE + (unsigned long) p->thread_info)) - 1;
391 *childregs = *regs;
392 childregs->eax = 0;
393 childregs->esp = esp;
394
395 p->thread.esp = (unsigned long) childregs;
396 p->thread.esp0 = (unsigned long) (childregs+1);
397
398 p->thread.eip = (unsigned long) ret_from_fork;
399
400 savesegment(fs,p->thread.fs);
401 savesegment(gs,p->thread.gs);
402
403 tsk = current;
404 if (unlikely(NULL != tsk->thread.io_bitmap_ptr)) {
405 p->thread.io_bitmap_ptr = kmalloc(IO_BITMAP_BYTES, GFP_KERNEL);
406 if (!p->thread.io_bitmap_ptr) {
407 p->thread.io_bitmap_max = 0;
408 return -ENOMEM;
409 }
410 memcpy(p->thread.io_bitmap_ptr, tsk->thread.io_bitmap_ptr,
411 IO_BITMAP_BYTES);
412 }
413
414 /*
415 * Set a new TLS for the child thread?
416 */
417 if (clone_flags & CLONE_SETTLS) {
418 struct desc_struct *desc;
419 struct user_desc info;
420 int idx;
421
422 err = -EFAULT;
423 if (copy_from_user(&info, (void __user *)childregs->esi, sizeof(info)))
424 goto out;
425 err = -EINVAL;
426 if (LDT_empty(&info))
427 goto out;
428
429 idx = info.entry_number;
430 if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX)
431 goto out;
432
433 desc = p->thread.tls_array + idx - GDT_ENTRY_TLS_MIN;
434 desc->a = LDT_entry_a(&info);
435 desc->b = LDT_entry_b(&info);
436 }
437
438 err = 0;
439 out:
440 if (err && p->thread.io_bitmap_ptr) {
441 kfree(p->thread.io_bitmap_ptr);
442 p->thread.io_bitmap_max = 0;
443 }
444 return err;
445 }
446
447 /*
448 * fill in the user structure for a core dump..
449 */
450 void dump_thread(struct pt_regs * regs, struct user * dump)
451 {
452 int i;
453
454 /* changed the size calculations - should hopefully work better. lbt */
455 dump->magic = CMAGIC;
456 dump->start_code = 0;
457 dump->start_stack = regs->esp & ~(PAGE_SIZE - 1);
458 dump->u_tsize = ((unsigned long) current->mm->end_code) >> PAGE_SHIFT;
459 dump->u_dsize = ((unsigned long) (current->mm->brk + (PAGE_SIZE-1))) >> PAGE_SHIFT;
460 dump->u_dsize -= dump->u_tsize;
461 dump->u_ssize = 0;
462 for (i = 0; i < 8; i++)
463 dump->u_debugreg[i] = current->thread.debugreg[i];
464
465 if (dump->start_stack < TASK_SIZE)
466 dump->u_ssize = ((unsigned long) (TASK_SIZE - dump->start_stack)) >> PAGE_SHIFT;
467
468 dump->regs.ebx = regs->ebx;
469 dump->regs.ecx = regs->ecx;
470 dump->regs.edx = regs->edx;
471 dump->regs.esi = regs->esi;
472 dump->regs.edi = regs->edi;
473 dump->regs.ebp = regs->ebp;
474 dump->regs.eax = regs->eax;
475 dump->regs.ds = regs->xds;
476 dump->regs.es = regs->xes;
477 savesegment(fs,dump->regs.fs);
478 savesegment(gs,dump->regs.gs);
479 dump->regs.orig_eax = regs->orig_eax;
480 dump->regs.eip = regs->eip;
481 dump->regs.cs = regs->xcs;
482 dump->regs.eflags = regs->eflags;
483 dump->regs.esp = regs->esp;
484 dump->regs.ss = regs->xss;
485
486 dump->u_fpvalid = dump_fpu (regs, &dump->i387);
487 }
488
489 /*
490 * Capture the user space registers if the task is not running (in user space)
491 */
492 int dump_task_regs(struct task_struct *tsk, elf_gregset_t *regs)
493 {
494 struct pt_regs ptregs;
495
496 ptregs = *(struct pt_regs *)
497 ((unsigned long)tsk->thread_info+THREAD_SIZE - sizeof(ptregs));
498 ptregs.xcs &= 0xffff;
499 ptregs.xds &= 0xffff;
500 ptregs.xes &= 0xffff;
501 ptregs.xss &= 0xffff;
502
503 elf_core_copy_regs(regs, &ptregs);
504
505 return 1;
506 }
507
508 static inline void
509 handle_io_bitmap(struct thread_struct *next, struct tss_struct *tss)
510 {
511 if (!next->io_bitmap_ptr) {
512 /*
513 * Disable the bitmap via an invalid offset. We still cache
514 * the previous bitmap owner and the IO bitmap contents:
515 */
516 tss->io_bitmap_base = INVALID_IO_BITMAP_OFFSET;
517 return;
518 }
519 if (likely(next == tss->io_bitmap_owner)) {
520 /*
521 * Previous owner of the bitmap (hence the bitmap content)
522 * matches the next task, we dont have to do anything but
523 * to set a valid offset in the TSS:
524 */
525 tss->io_bitmap_base = IO_BITMAP_OFFSET;
526 return;
527 }
528 /*
529 * Lazy TSS's I/O bitmap copy. We set an invalid offset here
530 * and we let the task to get a GPF in case an I/O instruction
531 * is performed. The handler of the GPF will verify that the
532 * faulting task has a valid I/O bitmap and, it true, does the
533 * real copy and restart the instruction. This will save us
534 * redundant copies when the currently switched task does not
535 * perform any I/O during its timeslice.
536 */
537 tss->io_bitmap_base = INVALID_IO_BITMAP_OFFSET_LAZY;
538 }
539 /*
540 * This special macro can be used to load a debugging register
541 */
542 #define loaddebug(thread,register) \
543 __asm__("movl %0,%%db" #register \
544 : /* no output */ \
545 :"r" (thread->debugreg[register]))
546
547 /*
548 * switch_to(x,yn) should switch tasks from x to y.
549 *
550 * We fsave/fwait so that an exception goes off at the right time
551 * (as a call from the fsave or fwait in effect) rather than to
552 * the wrong process. Lazy FP saving no longer makes any sense
553 * with modern CPU's, and this simplifies a lot of things (SMP
554 * and UP become the same).
555 *
556 * NOTE! We used to use the x86 hardware context switching. The
557 * reason for not using it any more becomes apparent when you
558 * try to recover gracefully from saved state that is no longer
559 * valid (stale segment register values in particular). With the
560 * hardware task-switch, there is no way to fix up bad state in
561 * a reasonable manner.
562 *
563 * The fact that Intel documents the hardware task-switching to
564 * be slow is a fairly red herring - this code is not noticeably
565 * faster. However, there _is_ some room for improvement here,
566 * so the performance issues may eventually be a valid point.
567 * More important, however, is the fact that this allows us much
568 * more flexibility.
569 *
570 * The return value (in %eax) will be the "prev" task after
571 * the task-switch, and shows up in ret_from_fork in entry.S,
572 * for example.
573 */
574 struct task_struct fastcall * __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
575 {
576 struct thread_struct *prev = &prev_p->thread,
577 *next = &next_p->thread;
578 int cpu = smp_processor_id();
579 struct tss_struct *tss = &per_cpu(init_tss, cpu);
580
581 /* never put a printk in __switch_to... printk() calls wake_up*() indirectly */
582
583 __unlazy_fpu(prev_p);
584
585 /*
586 * Reload esp0, LDT and the page table pointer:
587 */
588 load_esp0(tss, next);
589
590 /*
591 * Load the per-thread Thread-Local Storage descriptor.
592 */
593 load_TLS(next, cpu);
594
595 /*
596 * Save away %fs and %gs. No need to save %es and %ds, as
597 * those are always kernel segments while inside the kernel.
598 */
599 asm volatile("movl %%fs,%0":"=m" (*(int *)&prev->fs));
600 asm volatile("movl %%gs,%0":"=m" (*(int *)&prev->gs));
601
602 /*
603 * Restore %fs and %gs if needed.
604 */
605 if (unlikely(prev->fs | prev->gs | next->fs | next->gs)) {
606 loadsegment(fs, next->fs);
607 loadsegment(gs, next->gs);
608 }
609
610 /*
611 * Now maybe reload the debug registers
612 */
613 if (unlikely(next->debugreg[7])) {
614 loaddebug(next, 0);
615 loaddebug(next, 1);
616 loaddebug(next, 2);
617 loaddebug(next, 3);
618 /* no 4 and 5 */
619 loaddebug(next, 6);
620 loaddebug(next, 7);
621 }
622
623 if (unlikely(prev->io_bitmap_ptr || next->io_bitmap_ptr))
624 handle_io_bitmap(next, tss);
625
626 return prev_p;
627 }
628
629 asmlinkage int sys_fork(struct pt_regs regs)
630 {
631 return do_fork(SIGCHLD, regs.esp, ®s, 0, NULL, NULL);
632 }
633
634 asmlinkage int sys_clone(struct pt_regs regs)
635 {
636 unsigned long clone_flags;
637 unsigned long newsp;
638 int __user *parent_tidptr, *child_tidptr;
639
640 clone_flags = regs.ebx;
641 newsp = regs.ecx;
642 parent_tidptr = (int __user *)regs.edx;
643 child_tidptr = (int __user *)regs.edi;
644 if (!newsp)
645 newsp = regs.esp;
646 return do_fork(clone_flags, newsp, ®s, 0, parent_tidptr, child_tidptr);
647 }
648
649 /*
650 * This is trivial, and on the face of it looks like it
651 * could equally well be done in user mode.
652 *
653 * Not so, for quite unobvious reasons - register pressure.
654 * In user mode vfork() cannot have a stack frame, and if
655 * done by calling the "clone()" system call directly, you
656 * do not have enough call-clobbered registers to hold all
657 * the information you need.
658 */
659 asmlinkage int sys_vfork(struct pt_regs regs)
660 {
661 return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, regs.esp, ®s, 0, NULL, NULL);
662 }
663
664 /*
665 * sys_execve() executes a new program.
666 */
667 asmlinkage int sys_execve(struct pt_regs regs)
668 {
669 int error;
670 char * filename;
671
672 filename = getname((char __user *) regs.ebx);
673 error = PTR_ERR(filename);
674 if (IS_ERR(filename))
675 goto out;
676 error = do_execve(filename,
677 (char __user * __user *) regs.ecx,
678 (char __user * __user *) regs.edx,
679 ®s);
680 if (error == 0) {
681 task_lock(current);
682 current->ptrace &= ~PT_DTRACE;
683 task_unlock(current);
684 /* Make sure we don't return using sysenter.. */
685 set_thread_flag(TIF_IRET);
686 }
687 putname(filename);
688 out:
689 return error;
690 }
691
692 #define top_esp (THREAD_SIZE - sizeof(unsigned long))
693 #define top_ebp (THREAD_SIZE - 2*sizeof(unsigned long))
694
695 unsigned long get_wchan(struct task_struct *p)
696 {
697 unsigned long ebp, esp, eip;
698 unsigned long stack_page;
699 int count = 0;
700 if (!p || p == current || p->state == TASK_RUNNING)
701 return 0;
702 stack_page = (unsigned long)p->thread_info;
703 esp = p->thread.esp;
704 if (!stack_page || esp < stack_page || esp > top_esp+stack_page)
705 return 0;
706 /* include/asm-i386/system.h:switch_to() pushes ebp last. */
707 ebp = *(unsigned long *) esp;
708 do {
709 if (ebp < stack_page || ebp > top_ebp+stack_page)
710 return 0;
711 eip = *(unsigned long *) (ebp+4);
712 if (!in_sched_functions(eip))
713 return eip;
714 ebp = *(unsigned long *) ebp;
715 } while (count++ < 16);
716 return 0;
717 }
718
719 /*
720 * sys_alloc_thread_area: get a yet unused TLS descriptor index.
721 */
722 static int get_free_idx(void)
723 {
724 struct thread_struct *t = ¤t->thread;
725 int idx;
726
727 for (idx = 0; idx < GDT_ENTRY_TLS_ENTRIES; idx++)
728 if (desc_empty(t->tls_array + idx))
729 return idx + GDT_ENTRY_TLS_MIN;
730 return -ESRCH;
731 }
732
733 /*
734 * Set a given TLS descriptor:
735 */
736 asmlinkage int sys_set_thread_area(struct user_desc __user *u_info)
737 {
738 struct thread_struct *t = ¤t->thread;
739 struct user_desc info;
740 struct desc_struct *desc;
741 int cpu, idx;
742
743 if (copy_from_user(&info, u_info, sizeof(info)))
744 return -EFAULT;
745 idx = info.entry_number;
746
747 /*
748 * index -1 means the kernel should try to find and
749 * allocate an empty descriptor:
750 */
751 if (idx == -1) {
752 idx = get_free_idx();
753 if (idx < 0)
754 return idx;
755 if (put_user(idx, &u_info->entry_number))
756 return -EFAULT;
757 }
758
759 if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX)
760 return -EINVAL;
761
762 desc = t->tls_array + idx - GDT_ENTRY_TLS_MIN;
763
764 /*
765 * We must not get preempted while modifying the TLS.
766 */
767 cpu = get_cpu();
768
769 if (LDT_empty(&info)) {
770 desc->a = 0;
771 desc->b = 0;
772 } else {
773 desc->a = LDT_entry_a(&info);
774 desc->b = LDT_entry_b(&info);
775 }
776 load_TLS(t, cpu);
777
778 put_cpu();
779
780 return 0;
781 }
782
783 /*
784 * Get the current Thread-Local Storage area:
785 */
786
787 #define GET_BASE(desc) ( \
788 (((desc)->a >> 16) & 0x0000ffff) | \
789 (((desc)->b << 16) & 0x00ff0000) | \
790 ( (desc)->b & 0xff000000) )
791
792 #define GET_LIMIT(desc) ( \
793 ((desc)->a & 0x0ffff) | \
794 ((desc)->b & 0xf0000) )
795
796 #define GET_32BIT(desc) (((desc)->b >> 22) & 1)
797 #define GET_CONTENTS(desc) (((desc)->b >> 10) & 3)
798 #define GET_WRITABLE(desc) (((desc)->b >> 9) & 1)
799 #define GET_LIMIT_PAGES(desc) (((desc)->b >> 23) & 1)
800 #define GET_PRESENT(desc) (((desc)->b >> 15) & 1)
801 #define GET_USEABLE(desc) (((desc)->b >> 20) & 1)
802
803 asmlinkage int sys_get_thread_area(struct user_desc __user *u_info)
804 {
805 struct user_desc info;
806 struct desc_struct *desc;
807 int idx;
808
809 if (get_user(idx, &u_info->entry_number))
810 return -EFAULT;
811 if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX)
812 return -EINVAL;
813
814 desc = current->thread.tls_array + idx - GDT_ENTRY_TLS_MIN;
815
816 info.entry_number = idx;
817 info.base_addr = GET_BASE(desc);
818 info.limit = GET_LIMIT(desc);
819 info.seg_32bit = GET_32BIT(desc);
820 info.contents = GET_CONTENTS(desc);
821 info.read_exec_only = !GET_WRITABLE(desc);
822 info.limit_in_pages = GET_LIMIT_PAGES(desc);
823 info.seg_not_present = !GET_PRESENT(desc);
824 info.useable = GET_USEABLE(desc);
825
826 if (copy_to_user(u_info, &info, sizeof(info)))
827 return -EFAULT;
828 return 0;
829 }
830
831
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