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