arch/x86_64/kernel/process.c

   1 /*
   2  *  linux/arch/x86-64/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  *  X86-64 port
  10  *      Andi Kleen.
  11  *
  12  *      CPU hotplug support - ashok.raj@intel.com
  13  *  $Id: process.c,v 1.38 2002/01/15 10:08:03 ak Exp $
  14  */
  15
  16 /*
  17  * This file handles the architecture-dependent parts of process handling..
  18  */
  19
  20 #include <stdarg.h>
  21
  22 #include <linux/cpu.h>
  23 #include <linux/errno.h>
  24 #include <linux/sched.h>
  25 #include <linux/kernel.h>
  26 #include <linux/mm.h>
  27 #include <linux/elfcore.h>
  28 #include <linux/smp.h>
  29 #include <linux/slab.h>
  30 #include <linux/user.h>
  31 #include <linux/module.h>
  32 #include <linux/a.out.h>
  33 #include <linux/interrupt.h>
  34 #include <linux/delay.h>
  35 #include <linux/ptrace.h>
  36 #include <linux/utsname.h>
  37 #include <linux/random.h>
  38 #include <linux/notifier.h>
  39 #include <linux/kprobes.h>
  40
  41 #include <asm/uaccess.h>
  42 #include <asm/pgtable.h>
  43 #include <asm/system.h>
  44 #include <asm/io.h>
  45 #include <asm/processor.h>
  46 #include <asm/i387.h>
  47 #include <asm/mmu_context.h>
  48 #include <asm/pda.h>
  49 #include <asm/prctl.h>
  50 #include <asm/kdebug.h>
  51 #include <asm/desc.h>
  52 #include <asm/proto.h>
  53 #include <asm/ia32.h>
  54 #include <asm/idle.h>
  55
  56 asmlinkage extern void ret_from_fork(void);
  57
  58 unsigned long kernel_thread_flags = CLONE_VM | CLONE_UNTRACED;
  59
  60 unsigned long boot_option_idle_override = 0;
  61 EXPORT_SYMBOL(boot_option_idle_override);
  62
  63 /*
  64  * Powermanagement idle function, if any..
  65  */
  66 void (*pm_idle)(void);
  67 static DEFINE_PER_CPU(unsigned int, cpu_idle_state);
  68
  69 static ATOMIC_NOTIFIER_HEAD(idle_notifier);
  70
  71 void idle_notifier_register(struct notifier_block *n)
  72 {
  73         atomic_notifier_chain_register(&idle_notifier, n);
  74 }
  75 EXPORT_SYMBOL_GPL(idle_notifier_register);
  76
  77 void idle_notifier_unregister(struct notifier_block *n)
  78 {
  79         atomic_notifier_chain_unregister(&idle_notifier, n);
  80 }
  81 EXPORT_SYMBOL(idle_notifier_unregister);
  82
  83 enum idle_state { CPU_IDLE, CPU_NOT_IDLE };
  84 static DEFINE_PER_CPU(enum idle_state, idle_state) = CPU_NOT_IDLE;
  85
  86 void enter_idle(void)
  87 {
  88         __get_cpu_var(idle_state) = CPU_IDLE;
  89         atomic_notifier_call_chain(&idle_notifier, IDLE_START, NULL);
  90 }
  91
  92 static void __exit_idle(void)
  93 {
  94         __get_cpu_var(idle_state) = CPU_NOT_IDLE;
  95         atomic_notifier_call_chain(&idle_notifier, IDLE_END, NULL);
  96 }
  97
  98 /* Called from interrupts to signify idle end */
  99 void exit_idle(void)
 100 {
 101         if (current->pid | read_pda(irqcount))
 102                 return;
 103         __exit_idle();
 104 }
 105
 106 /*
 107  * We use this if we don't have any better
 108  * idle routine..
 109  */
 110 static void default_idle(void)
 111 {
 112         local_irq_enable();
 113
 114         clear_thread_flag(TIF_POLLING_NRFLAG);
 115         smp_mb__after_clear_bit();
 116         while (!need_resched()) {
 117                 local_irq_disable();
 118                 if (!need_resched())
 119                         safe_halt();
 120                 else
 121                         local_irq_enable();
 122         }
 123         set_thread_flag(TIF_POLLING_NRFLAG);
 124 }
 125
 126 /*
 127  * On SMP it's slightly faster (but much more power-consuming!)
 128  * to poll the ->need_resched flag instead of waiting for the
 129  * cross-CPU IPI to arrive. Use this option with caution.
 130  */
 131 static void poll_idle (void)
 132 {
 133         local_irq_enable();
 134
 135         asm volatile(
 136                 "2:"
 137                 "testl %0,%1;"
 138                 "rep; nop;"
 139                 "je 2b;"
 140                 : :
 141                 "i" (_TIF_NEED_RESCHED),
 142                 "m" (current_thread_info()->flags));
 143 }
 144
 145 void cpu_idle_wait(void)
 146 {
 147         unsigned int cpu, this_cpu = get_cpu();
 148         cpumask_t map;
 149
 150         set_cpus_allowed(current, cpumask_of_cpu(this_cpu));
 151         put_cpu();
 152
 153         cpus_clear(map);
 154         for_each_online_cpu(cpu) {
 155                 per_cpu(cpu_idle_state, cpu) = 1;
 156                 cpu_set(cpu, map);
 157         }
 158
 159         __get_cpu_var(cpu_idle_state) = 0;
 160
 161         wmb();
 162         do {
 163                 ssleep(1);
 164                 for_each_online_cpu(cpu) {
 165                         if (cpu_isset(cpu, map) &&
 166                                         !per_cpu(cpu_idle_state, cpu))
 167                                 cpu_clear(cpu, map);
 168                 }
 169                 cpus_and(map, map, cpu_online_map);
 170         } while (!cpus_empty(map));
 171 }
 172 EXPORT_SYMBOL_GPL(cpu_idle_wait);
 173
 174 #ifdef CONFIG_HOTPLUG_CPU
 175 DECLARE_PER_CPU(int, cpu_state);
 176
 177 #include <asm/nmi.h>
 178 /* We halt the CPU with physical CPU hotplug */
 179 static inline void play_dead(void)
 180 {
 181         idle_task_exit();
 182         wbinvd();
 183         mb();
 184         /* Ack it */
 185         __get_cpu_var(cpu_state) = CPU_DEAD;
 186
 187         local_irq_disable();
 188         while (1)
 189                 halt();
 190 }
 191 #else
 192 static inline void play_dead(void)
 193 {
 194         BUG();
 195 }
 196 #endif /* CONFIG_HOTPLUG_CPU */
 197
 198 /*
 199  * The idle thread. There's no useful work to be
 200  * done, so just try to conserve power and have a
 201  * low exit latency (ie sit in a loop waiting for
 202  * somebody to say that they'd like to reschedule)
 203  */
 204 void cpu_idle (void)
 205 {
 206         set_thread_flag(TIF_POLLING_NRFLAG);
 207
 208         /* endless idle loop with no priority at all */
 209         while (1) {
 210                 while (!need_resched()) {
 211                         void (*idle)(void);
 212
 213                         if (__get_cpu_var(cpu_idle_state))
 214                                 __get_cpu_var(cpu_idle_state) = 0;
 215
 216                         rmb();
 217                         idle = pm_idle;
 218                         if (!idle)
 219                                 idle = default_idle;
 220                         if (cpu_is_offline(smp_processor_id()))
 221                                 play_dead();
 222                         enter_idle();
 223                         idle();
 224                         __exit_idle();
 225                 }
 226
 227                 preempt_enable_no_resched();
 228                 schedule();
 229                 preempt_disable();
 230         }
 231 }
 232
 233 /*
 234  * This uses new MONITOR/MWAIT instructions on P4 processors with PNI,
 235  * which can obviate IPI to trigger checking of need_resched.
 236  * We execute MONITOR against need_resched and enter optimized wait state
 237  * through MWAIT. Whenever someone changes need_resched, we would be woken
 238  * up from MWAIT (without an IPI).
 239  */
 240 static void mwait_idle(void)
 241 {
 242         local_irq_enable();
 243
 244         while (!need_resched()) {
 245                 __monitor((void *)&current_thread_info()->flags, 0, 0);
 246                 smp_mb();
 247                 if (need_resched())
 248                         break;
 249                 __mwait(0, 0);
 250         }
 251 }
 252
 253 void __cpuinit select_idle_routine(const struct cpuinfo_x86 *c)
 254 {
 255         static int printed;
 256         if (cpu_has(c, X86_FEATURE_MWAIT)) {
 257                 /*
 258                  * Skip, if setup has overridden idle.
 259                  * One CPU supports mwait => All CPUs supports mwait
 260                  */
 261                 if (!pm_idle) {
 262                         if (!printed) {
 263                                 printk("using mwait in idle threads.\n");
 264                                 printed = 1;
 265                         }
 266                         pm_idle = mwait_idle;
 267                 }
 268         }
 269 }
 270
 271 static int __init idle_setup (char *str)
 272 {
 273         if (!strncmp(str, "poll", 4)) {
 274                 printk("using polling idle threads.\n");
 275                 pm_idle = poll_idle;
 276         }
 277
 278         boot_option_idle_override = 1;
 279         return 1;
 280 }
 281
 282 __setup("idle=", idle_setup);
 283
 284 /* Prints also some state that isn't saved in the pt_regs */
 285 void __show_regs(struct pt_regs * regs)
 286 {
 287         unsigned long cr0 = 0L, cr2 = 0L, cr3 = 0L, cr4 = 0L, fs, gs, shadowgs;
 288         unsigned int fsindex,gsindex;
 289         unsigned int ds,cs,es;
 290
 291         printk("\n");
 292         print_modules();
 293         printk("Pid: %d, comm: %.20s %s %s %.*s\n",
 294                 current->pid, current->comm, print_tainted(),
 295                 system_utsname.release,
 296                 (int)strcspn(system_utsname.version, " "),
 297                 system_utsname.version);
 298         printk("RIP: %04lx:[<%016lx>] ", regs->cs & 0xffff, regs->rip);
 299         printk_address(regs->rip);
 300         printk("\nRSP: %04lx:%016lx  EFLAGS: %08lx\n", regs->ss, regs->rsp,
 301                 regs->eflags);
 302         printk("RAX: %016lx RBX: %016lx RCX: %016lx\n",
 303                regs->rax, regs->rbx, regs->rcx);
 304         printk("RDX: %016lx RSI: %016lx RDI: %016lx\n",
 305                regs->rdx, regs->rsi, regs->rdi);
 306         printk("RBP: %016lx R08: %016lx R09: %016lx\n",
 307                regs->rbp, regs->r8, regs->r9);
 308         printk("R10: %016lx R11: %016lx R12: %016lx\n",
 309                regs->r10, regs->r11, regs->r12);
 310         printk("R13: %016lx R14: %016lx R15: %016lx\n",
 311                regs->r13, regs->r14, regs->r15);
 312
 313         asm("movl %%ds,%0" : "=r" (ds));
 314         asm("movl %%cs,%0" : "=r" (cs));
 315         asm("movl %%es,%0" : "=r" (es));
 316         asm("movl %%fs,%0" : "=r" (fsindex));
 317         asm("movl %%gs,%0" : "=r" (gsindex));
 318
 319         rdmsrl(MSR_FS_BASE, fs);
 320         rdmsrl(MSR_GS_BASE, gs);
 321         rdmsrl(MSR_KERNEL_GS_BASE, shadowgs);
 322
 323         asm("movq %%cr0, %0": "=r" (cr0));
 324         asm("movq %%cr2, %0": "=r" (cr2));
 325         asm("movq %%cr3, %0": "=r" (cr3));
 326         asm("movq %%cr4, %0": "=r" (cr4));
 327
 328         printk("FS:  %016lx(%04x) GS:%016lx(%04x) knlGS:%016lx\n",
 329                fs,fsindex,gs,gsindex,shadowgs);
 330         printk("CS:  %04x DS: %04x ES: %04x CR0: %016lx\n", cs, ds, es, cr0);
 331         printk("CR2: %016lx CR3: %016lx CR4: %016lx\n", cr2, cr3, cr4);
 332 }
 333
 334 void show_regs(struct pt_regs *regs)
 335 {
 336         printk("CPU %d:", smp_processor_id());
 337         __show_regs(regs);
 338         show_trace(&regs->rsp);
 339 }
 340
 341 /*
 342  * Free current thread data structures etc..
 343  */
 344 void exit_thread(void)
 345 {
 346         struct task_struct *me = current;
 347         struct thread_struct *t = &me->thread;
 348
 349         if (me->thread.io_bitmap_ptr) {
 350                 struct tss_struct *tss = &per_cpu(init_tss, get_cpu());
 351
 352                 kfree(t->io_bitmap_ptr);
 353                 t->io_bitmap_ptr = NULL;
 354                 /*
 355                  * Careful, clear this in the TSS too:
 356                  */
 357                 memset(tss->io_bitmap, 0xff, t->io_bitmap_max);
 358                 t->io_bitmap_max = 0;
 359                 put_cpu();
 360         }
 361 }
 362
 363 void flush_thread(void)
 364 {
 365         struct task_struct *tsk = current;
 366         struct thread_info *t = current_thread_info();
 367
 368         if (t->flags & _TIF_ABI_PENDING)
 369                 t->flags ^= (_TIF_ABI_PENDING | _TIF_IA32);
 370
 371         tsk->thread.debugreg0 = 0;
 372         tsk->thread.debugreg1 = 0;
 373         tsk->thread.debugreg2 = 0;
 374         tsk->thread.debugreg3 = 0;
 375         tsk->thread.debugreg6 = 0;
 376         tsk->thread.debugreg7 = 0;
 377         memset(tsk->thread.tls_array, 0, sizeof(tsk->thread.tls_array));
 378         /*
 379          * Forget coprocessor state..
 380          */
 381         clear_fpu(tsk);
 382         clear_used_math();
 383 }
 384
 385 void release_thread(struct task_struct *dead_task)
 386 {
 387         if (dead_task->mm) {
 388                 if (dead_task->mm->context.size) {
 389                         printk("WARNING: dead process %8s still has LDT? <%p/%d>\n",
 390                                         dead_task->comm,
 391                                         dead_task->mm->context.ldt,
 392                                         dead_task->mm->context.size);
 393                         BUG();
 394                 }
 395         }
 396 }
 397
 398 static inline void set_32bit_tls(struct task_struct *t, int tls, u32 addr)
 399 {
 400         struct user_desc ud = {
 401                 .base_addr = addr,
 402                 .limit = 0xfffff,
 403                 .seg_32bit = 1,
 404                 .limit_in_pages = 1,
 405                 .useable = 1,
 406         };
 407         struct n_desc_struct *desc = (void *)t->thread.tls_array;
 408         desc += tls;
 409         desc->a = LDT_entry_a(&ud);
 410         desc->b = LDT_entry_b(&ud);
 411 }
 412
 413 static inline u32 read_32bit_tls(struct task_struct *t, int tls)
 414 {
 415         struct desc_struct *desc = (void *)t->thread.tls_array;
 416         desc += tls;
 417         return desc->base0 |
 418                 (((u32)desc->base1) << 16) |
 419                 (((u32)desc->base2) << 24);
 420 }
 421
 422 /*
 423  * This gets called before we allocate a new thread and copy
 424  * the current task into it.
 425  */
 426 void prepare_to_copy(struct task_struct *tsk)
 427 {
 428         unlazy_fpu(tsk);
 429 }
 430
 431 int copy_thread(int nr, unsigned long clone_flags, unsigned long rsp,
 432                 unsigned long unused,
 433         struct task_struct * p, struct pt_regs * regs)
 434 {
 435         int err;
 436         struct pt_regs * childregs;
 437         struct task_struct *me = current;
 438
 439         childregs = ((struct pt_regs *)
 440                         (THREAD_SIZE + task_stack_page(p))) - 1;
 441         *childregs = *regs;
 442
 443         childregs->rax = 0;
 444         childregs->rsp = rsp;
 445         if (rsp == ~0UL)
 446                 childregs->rsp = (unsigned long)childregs;
 447
 448         p->thread.rsp = (unsigned long) childregs;
 449         p->thread.rsp0 = (unsigned long) (childregs+1);
 450         p->thread.userrsp = me->thread.userrsp;
 451
 452         set_tsk_thread_flag(p, TIF_FORK);
 453
 454         p->thread.fs = me->thread.fs;
 455         p->thread.gs = me->thread.gs;
 456
 457         asm("mov %%gs,%0" : "=m" (p->thread.gsindex));
 458         asm("mov %%fs,%0" : "=m" (p->thread.fsindex));
 459         asm("mov %%es,%0" : "=m" (p->thread.es));
 460         asm("mov %%ds,%0" : "=m" (p->thread.ds));
 461
 462         if (unlikely(me->thread.io_bitmap_ptr != NULL)) {
 463                 p->thread.io_bitmap_ptr = kmalloc(IO_BITMAP_BYTES, GFP_KERNEL);
 464                 if (!p->thread.io_bitmap_ptr) {
 465                         p->thread.io_bitmap_max = 0;
 466                         return -ENOMEM;
 467                 }
 468                 memcpy(p->thread.io_bitmap_ptr, me->thread.io_bitmap_ptr,
 469                                 IO_BITMAP_BYTES);
 470         }
 471
 472         /*
 473          * Set a new TLS for the child thread?
 474          */
 475         if (clone_flags & CLONE_SETTLS) {
 476 #ifdef CONFIG_IA32_EMULATION
 477                 if (test_thread_flag(TIF_IA32))
 478                         err = ia32_child_tls(p, childregs);
 479                 else
 480 #endif
 481                         err = do_arch_prctl(p, ARCH_SET_FS, childregs->r8);
 482                 if (err)
 483                         goto out;
 484         }
 485         err = 0;
 486 out:
 487         if (err && p->thread.io_bitmap_ptr) {
 488                 kfree(p->thread.io_bitmap_ptr);
 489                 p->thread.io_bitmap_max = 0;
 490         }
 491         return err;
 492 }
 493
 494 /*
 495  * This special macro can be used to load a debugging register
 496  */
 497 #define loaddebug(thread,r) set_debugreg(thread->debugreg ## r, r)
 498
 499 /*
 500  *      switch_to(x,y) should switch tasks from x to y.
 501  *
 502  * This could still be optimized:
 503  * - fold all the options into a flag word and test it with a single test.
 504  * - could test fs/gs bitsliced
 505  *
 506  * Kprobes not supported here. Set the probe on schedule instead.
 507  */
 508 __kprobes struct task_struct *
 509 __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
 510 {
 511         struct thread_struct *prev = &prev_p->thread,
 512                                  *next = &next_p->thread;
 513         int cpu = smp_processor_id();
 514         struct tss_struct *tss = &per_cpu(init_tss, cpu);
 515
 516         /*
 517          * Reload esp0, LDT and the page table pointer:
 518          */
 519         tss->rsp0 = next->rsp0;
 520
 521         /*
 522          * Switch DS and ES.
 523          * This won't pick up thread selector changes, but I guess that is ok.
 524          */
 525         asm volatile("mov %%es,%0" : "=m" (prev->es));
 526         if (unlikely(next->es | prev->es))
 527                 loadsegment(es, next->es);
 528
 529         asm volatile ("mov %%ds,%0" : "=m" (prev->ds));
 530         if (unlikely(next->ds | prev->ds))
 531                 loadsegment(ds, next->ds);
 532
 533         load_TLS(next, cpu);
 534
 535         /*
 536          * Switch FS and GS.
 537          */
 538         {
 539                 unsigned fsindex;
 540                 asm volatile("movl %%fs,%0" : "=r" (fsindex));
 541                 /* segment register != 0 always requires a reload.
 542                    also reload when it has changed.
 543                    when prev process used 64bit base always reload
 544                    to avoid an information leak. */
 545                 if (unlikely(fsindex | next->fsindex | prev->fs)) {
 546                         loadsegment(fs, next->fsindex);
 547                         /* check if the user used a selector != 0
 548                          * if yes clear 64bit base, since overloaded base
 549                          * is always mapped to the Null selector
 550                          */
 551                         if (fsindex)
 552                         prev->fs = 0;
 553                 }
 554                 /* when next process has a 64bit base use it */
 555                 if (next->fs)
 556                         wrmsrl(MSR_FS_BASE, next->fs);
 557                 prev->fsindex = fsindex;
 558         }
 559         {
 560                 unsigned gsindex;
 561                 asm volatile("movl %%gs,%0" : "=r" (gsindex));
 562                 if (unlikely(gsindex | next->gsindex | prev->gs)) {
 563                         load_gs_index(next->gsindex);
 564                         if (gsindex)
 565                         prev->gs = 0;
 566                 }
 567                 if (next->gs)
 568                         wrmsrl(MSR_KERNEL_GS_BASE, next->gs);
 569                 prev->gsindex = gsindex;
 570         }
 571
 572         /*
 573          * Switch the PDA and FPU contexts.
 574          */
 575         prev->userrsp = read_pda(oldrsp);
 576         write_pda(oldrsp, next->userrsp);
 577         write_pda(pcurrent, next_p);
 578
 579         /* This must be here to ensure both math_state_restore() and
 580            kernel_fpu_begin() work consistently.
 581            And the AMD workaround requires it to be after DS reload. */
 582         unlazy_fpu(prev_p);
 583         write_pda(kernelstack,
 584                   task_stack_page(next_p) + THREAD_SIZE - PDA_STACKOFFSET);
 585
 586         /*
 587          * Now maybe reload the debug registers
 588          */
 589         if (unlikely(next->debugreg7)) {
 590                 loaddebug(next, 0);
 591                 loaddebug(next, 1);
 592                 loaddebug(next, 2);
 593                 loaddebug(next, 3);
 594                 /* no 4 and 5 */
 595                 loaddebug(next, 6);
 596                 loaddebug(next, 7);
 597         }
 598
 599
 600         /*
 601          * Handle the IO bitmap
 602          */
 603         if (unlikely(prev->io_bitmap_ptr || next->io_bitmap_ptr)) {
 604                 if (next->io_bitmap_ptr)
 605                         /*
 606                          * Copy the relevant range of the IO bitmap.
 607                          * Normally this is 128 bytes or less:
 608                          */
 609                         memcpy(tss->io_bitmap, next->io_bitmap_ptr,
 610                                 max(prev->io_bitmap_max, next->io_bitmap_max));
 611                 else {
 612                         /*
 613                          * Clear any possible leftover bits:
 614                          */
 615                         memset(tss->io_bitmap, 0xff, prev->io_bitmap_max);
 616                 }
 617         }
 618
 619         return prev_p;
 620 }
 621
 622 /*
 623  * sys_execve() executes a new program.
 624  */
 625 asmlinkage
 626 long sys_execve(char __user *name, char __user * __user *argv,
 627                 char __user * __user *envp, struct pt_regs regs)
 628 {
 629         long error;
 630         char * filename;
 631
 632         filename = getname(name);
 633         error = PTR_ERR(filename);
 634         if (IS_ERR(filename))
 635                 return error;
 636         error = do_execve(filename, argv, envp, &regs);
 637         if (error == 0) {
 638                 task_lock(current);
 639                 current->ptrace &= ~PT_DTRACE;
 640                 task_unlock(current);
 641         }
 642         putname(filename);
 643         return error;
 644 }
 645
 646 void set_personality_64bit(void)
 647 {
 648         /* inherit personality from parent */
 649
 650         /* Make sure to be in 64bit mode */
 651         clear_thread_flag(TIF_IA32);
 652 }
 653
 654 asmlinkage long sys_fork(struct pt_regs *regs)
 655 {
 656         return do_fork(SIGCHLD, regs->rsp, regs, 0, NULL, NULL);
 657 }
 658
 659 asmlinkage long
 660 sys_clone(unsigned long clone_flags, unsigned long newsp,
 661           void __user *parent_tid, void __user *child_tid, struct pt_regs *regs)
 662 {
 663         if (!newsp)
 664                 newsp = regs->rsp;
 665         return do_fork(clone_flags, newsp, regs, 0, parent_tid, child_tid);
 666 }
 667
 668 /*
 669  * This is trivial, and on the face of it looks like it
 670  * could equally well be done in user mode.
 671  *
 672  * Not so, for quite unobvious reasons - register pressure.
 673  * In user mode vfork() cannot have a stack frame, and if
 674  * done by calling the "clone()" system call directly, you
 675  * do not have enough call-clobbered registers to hold all
 676  * the information you need.
 677  */
 678 asmlinkage long sys_vfork(struct pt_regs *regs)
 679 {
 680         return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, regs->rsp, regs, 0,
 681                     NULL, NULL);
 682 }
 683
 684 unsigned long get_wchan(struct task_struct *p)
 685 {
 686         unsigned long stack;
 687         u64 fp,rip;
 688         int count = 0;
 689
 690         if (!p || p == current || p->state==TASK_RUNNING)
 691                 return 0;
 692         stack = (unsigned long)task_stack_page(p);
 693         if (p->thread.rsp < stack || p->thread.rsp > stack+THREAD_SIZE)
 694                 return 0;
 695         fp = *(u64 *)(p->thread.rsp);
 696         do {
 697                 if (fp < (unsigned long)stack ||
 698                     fp > (unsigned long)stack+THREAD_SIZE)
 699                         return 0;
 700                 rip = *(u64 *)(fp+8);
 701                 if (!in_sched_functions(rip))
 702                         return rip;
 703                 fp = *(u64 *)fp;
 704         } while (count++ < 16);
 705         return 0;
 706 }
 707
 708 long do_arch_prctl(struct task_struct *task, int code, unsigned long addr)
 709 {
 710         int ret = 0;
 711         int doit = task == current;
 712         int cpu;
 713
 714         switch (code) {
 715         case ARCH_SET_GS:
 716                 if (addr >= TASK_SIZE_OF(task))
 717                         return -EPERM;
 718                 cpu = get_cpu();
 719                 /* handle small bases via the GDT because that's faster to
 720                    switch. */
 721                 if (addr <= 0xffffffff) {
 722                         set_32bit_tls(task, GS_TLS, addr);
 723                         if (doit) {
 724                                 load_TLS(&task->thread, cpu);
 725                                 load_gs_index(GS_TLS_SEL);
 726                         }
 727                         task->thread.gsindex = GS_TLS_SEL;
 728                         task->thread.gs = 0;
 729                 } else {
 730                         task->thread.gsindex = 0;
 731                         task->thread.gs = addr;
 732                         if (doit) {
 733                                 load_gs_index(0);
 734                                 ret = checking_wrmsrl(MSR_KERNEL_GS_BASE, addr);
 735                         }
 736                 }
 737                 put_cpu();
 738                 break;
 739         case ARCH_SET_FS:
 740                 /* Not strictly needed for fs, but do it for symmetry
 741                    with gs */
 742                 if (addr >= TASK_SIZE_OF(task))
 743                         return -EPERM;
 744                 cpu = get_cpu();
 745                 /* handle small bases via the GDT because that's faster to
 746                    switch. */
 747                 if (addr <= 0xffffffff) {
 748                         set_32bit_tls(task, FS_TLS, addr);
 749                         if (doit) {
 750                                 load_TLS(&task->thread, cpu);
 751                                 asm volatile("movl %0,%%fs" :: "r"(FS_TLS_SEL));
 752                         }
 753                         task->thread.fsindex = FS_TLS_SEL;
 754                         task->thread.fs = 0;
 755                 } else {
 756                         task->thread.fsindex = 0;
 757                         task->thread.fs = addr;
 758                         if (doit) {
 759                                 /* set the selector to 0 to not confuse
 760                                    __switch_to */
 761                                 asm volatile("movl %0,%%fs" :: "r" (0));
 762                                 ret = checking_wrmsrl(MSR_FS_BASE, addr);
 763                         }
 764                 }
 765                 put_cpu();
 766                 break;
 767         case ARCH_GET_FS: {
 768                 unsigned long base;
 769                 if (task->thread.fsindex == FS_TLS_SEL)
 770                         base = read_32bit_tls(task, FS_TLS);
 771                 else if (doit)
 772                         rdmsrl(MSR_FS_BASE, base);
 773                 else
 774                         base = task->thread.fs;
 775                 ret = put_user(base, (unsigned long __user *)addr);
 776                 break;
 777         }
 778         case ARCH_GET_GS: {
 779                 unsigned long base;
 780                 unsigned gsindex;
 781                 if (task->thread.gsindex == GS_TLS_SEL)
 782                         base = read_32bit_tls(task, GS_TLS);
 783                 else if (doit) {
 784                         asm("movl %%gs,%0" : "=r" (gsindex));
 785                         if (gsindex)
 786                                 rdmsrl(MSR_KERNEL_GS_BASE, base);
 787                         else
 788                                 base = task->thread.gs;
 789                 }
 790                 else
 791                         base = task->thread.gs;
 792                 ret = put_user(base, (unsigned long __user *)addr);
 793                 break;
 794         }
 795
 796         default:
 797                 ret = -EINVAL;
 798                 break;
 799         }
 800
 801         return ret;
 802 }
 803
 804 long sys_arch_prctl(int code, unsigned long addr)
 805 {
 806         return do_arch_prctl(current, code, addr);
 807 }
 808
 809 /*
 810  * Capture the user space registers if the task is not running (in user space)
 811  */
 812 int dump_task_regs(struct task_struct *tsk, elf_gregset_t *regs)
 813 {
 814         struct pt_regs *pp, ptregs;
 815
 816         pp = task_pt_regs(tsk);
 817
 818         ptregs = *pp;
 819         ptregs.cs &= 0xffff;
 820         ptregs.ss &= 0xffff;
 821
 822         elf_core_copy_regs(regs, &ptregs);
 823
 824         return 1;
 825 }
 826
 827 unsigned long arch_align_stack(unsigned long sp)
 828 {
 829         if (randomize_va_space)
 830                 sp -= get_random_int() % 8192;
 831         return sp & ~0xf;
 832 }