arch/x86_64/kernel/process-xen.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  *  Jun Nakajima <jun.nakajima@intel.com>
  16  *     Modified for Xen
  17  */
  18
  19 /*
  20  * This file handles the architecture-dependent parts of process handling..
  21  */
  22
  23 #include <stdarg.h>
  24
  25 #include <linux/cpu.h>
  26 #include <linux/errno.h>
  27 #include <linux/sched.h>
  28 #include <linux/kernel.h>
  29 #include <linux/mm.h>
  30 #include <linux/elfcore.h>
  31 #include <linux/smp.h>
  32 #include <linux/slab.h>
  33 #include <linux/user.h>
  34 #include <linux/module.h>
  35 #include <linux/a.out.h>
  36 #include <linux/interrupt.h>
  37 #include <linux/delay.h>
  38 #include <linux/ptrace.h>
  39 #include <linux/utsname.h>
  40 #include <linux/random.h>
  41 #include <linux/notifier.h>
  42 #include <linux/kprobes.h>
  43
  44 #include <asm/uaccess.h>
  45 #include <asm/pgtable.h>
  46 #include <asm/system.h>
  47 #include <asm/io.h>
  48 #include <asm/processor.h>
  49 #include <asm/i387.h>
  50 #include <asm/mmu_context.h>
  51 #include <asm/pda.h>
  52 #include <asm/prctl.h>
  53 #include <asm/kdebug.h>
  54 #include <xen/interface/dom0_ops.h>
  55 #include <xen/interface/physdev.h>
  56 #include <xen/interface/vcpu.h>
  57 #include <asm/desc.h>
  58 #include <asm/proto.h>
  59 #include <asm/hardirq.h>
  60 #include <asm/ia32.h>
  61 #include <asm/idle.h>
  62
  63 #include <xen/cpu_hotplug.h>
  64
  65 asmlinkage extern void ret_from_fork(void);
  66
  67 unsigned long kernel_thread_flags = CLONE_VM | CLONE_UNTRACED;
  68
  69 unsigned long boot_option_idle_override = 0;
  70 EXPORT_SYMBOL(boot_option_idle_override);
  71
  72 /*
  73  * Powermanagement idle function, if any..
  74  */
  75 void (*pm_idle)(void);
  76 static DEFINE_PER_CPU(unsigned int, cpu_idle_state);
  77
  78 static ATOMIC_NOTIFIER_HEAD(idle_notifier);
  79
  80 void idle_notifier_register(struct notifier_block *n)
  81 {
  82         atomic_notifier_chain_register(&idle_notifier, n);
  83 }
  84 EXPORT_SYMBOL_GPL(idle_notifier_register);
  85
  86 void idle_notifier_unregister(struct notifier_block *n)
  87 {
  88         atomic_notifier_chain_unregister(&idle_notifier, n);
  89 }
  90 EXPORT_SYMBOL(idle_notifier_unregister);
  91
  92 enum idle_state { CPU_IDLE, CPU_NOT_IDLE };
  93 static DEFINE_PER_CPU(enum idle_state, idle_state) = CPU_NOT_IDLE;
  94
  95 void enter_idle(void)
  96 {
  97         __get_cpu_var(idle_state) = CPU_IDLE;
  98         atomic_notifier_call_chain(&idle_notifier, IDLE_START, NULL);
  99 }
 100
 101 static void __exit_idle(void)
 102 {
 103         __get_cpu_var(idle_state) = CPU_NOT_IDLE;
 104         atomic_notifier_call_chain(&idle_notifier, IDLE_END, NULL);
 105 }
 106
 107 /* Called from interrupts to signify idle end */
 108 void exit_idle(void)
 109 {
 110         if (current->pid | read_pda(irqcount))
 111                 return;
 112         __exit_idle();
 113 }
 114
 115 /* XXX XEN doesn't use default_idle(), poll_idle(). Use xen_idle() instead. */
 116 void xen_idle(void)
 117 {
 118         local_irq_disable();
 119
 120         if (need_resched())
 121                 local_irq_enable();
 122         else {
 123                 clear_thread_flag(TIF_POLLING_NRFLAG);
 124                 smp_mb__after_clear_bit();
 125                 safe_halt();
 126                 set_thread_flag(TIF_POLLING_NRFLAG);
 127         }
 128 }
 129
 130 #ifdef CONFIG_HOTPLUG_CPU
 131 static inline void play_dead(void)
 132 {
 133         idle_task_exit();
 134         local_irq_disable();
 135         cpu_clear(smp_processor_id(), cpu_initialized);
 136         preempt_enable_no_resched();
 137         HYPERVISOR_vcpu_op(VCPUOP_down, smp_processor_id(), NULL);
 138         cpu_bringup();
 139 }
 140 #else
 141 static inline void play_dead(void)
 142 {
 143         BUG();
 144 }
 145 #endif /* CONFIG_HOTPLUG_CPU */
 146
 147 /*
 148  * The idle thread. There's no useful work to be
 149  * done, so just try to conserve power and have a
 150  * low exit latency (ie sit in a loop waiting for
 151  * somebody to say that they'd like to reschedule)
 152  */
 153 void cpu_idle (void)
 154 {
 155         set_thread_flag(TIF_POLLING_NRFLAG);
 156
 157         /* endless idle loop with no priority at all */
 158         while (1) {
 159                 while (!need_resched()) {
 160                         if (__get_cpu_var(cpu_idle_state))
 161                                 __get_cpu_var(cpu_idle_state) = 0;
 162                         rmb();
 163
 164                         if (cpu_is_offline(smp_processor_id()))
 165                                 play_dead();
 166                         enter_idle();
 167                         xen_idle();
 168                         __exit_idle();
 169                 }
 170
 171                 preempt_enable_no_resched();
 172                 schedule();
 173                 preempt_disable();
 174         }
 175 }
 176
 177 void cpu_idle_wait(void)
 178 {
 179         unsigned int cpu, this_cpu = get_cpu();
 180         cpumask_t map;
 181
 182         set_cpus_allowed(current, cpumask_of_cpu(this_cpu));
 183         put_cpu();
 184
 185         cpus_clear(map);
 186         for_each_online_cpu(cpu) {
 187                 per_cpu(cpu_idle_state, cpu) = 1;
 188                 cpu_set(cpu, map);
 189         }
 190
 191         __get_cpu_var(cpu_idle_state) = 0;
 192
 193         wmb();
 194         do {
 195                 ssleep(1);
 196                 for_each_online_cpu(cpu) {
 197                         if (cpu_isset(cpu, map) &&
 198                                         !per_cpu(cpu_idle_state, cpu))
 199                                 cpu_clear(cpu, map);
 200                 }
 201                 cpus_and(map, map, cpu_online_map);
 202         } while (!cpus_empty(map));
 203 }
 204 EXPORT_SYMBOL_GPL(cpu_idle_wait);
 205
 206 /* XXX XEN doesn't use mwait_idle(), select_idle_routine(), idle_setup(). */
 207 /* Always use xen_idle() instead. */
 208 void __cpuinit select_idle_routine(const struct cpuinfo_x86 *c) {}
 209
 210 /* Prints also some state that isn't saved in the pt_regs */
 211 void __show_regs(struct pt_regs * regs)
 212 {
 213         unsigned long fs, gs, shadowgs;
 214         unsigned int fsindex,gsindex;
 215         unsigned int ds,cs,es;
 216
 217         printk("\n");
 218         print_modules();
 219         printk("Pid: %d, comm: %.20s %s %s %.*s\n",
 220                 current->pid, current->comm, print_tainted(),
 221                 system_utsname.release,
 222                 (int)strcspn(system_utsname.version, " "),
 223                 system_utsname.version);
 224         printk("RIP: %04lx:[<%016lx>] ", regs->cs & 0xffff, regs->rip);
 225         printk_address(regs->rip);
 226         printk("\nRSP: %04lx:%016lx  EFLAGS: %08lx\n", regs->ss, regs->rsp,
 227                 regs->eflags);
 228         printk("RAX: %016lx RBX: %016lx RCX: %016lx\n",
 229                regs->rax, regs->rbx, regs->rcx);
 230         printk("RDX: %016lx RSI: %016lx RDI: %016lx\n",
 231                regs->rdx, regs->rsi, regs->rdi);
 232         printk("RBP: %016lx R08: %016lx R09: %016lx\n",
 233                regs->rbp, regs->r8, regs->r9);
 234         printk("R10: %016lx R11: %016lx R12: %016lx\n",
 235                regs->r10, regs->r11, regs->r12);
 236         printk("R13: %016lx R14: %016lx R15: %016lx\n",
 237                regs->r13, regs->r14, regs->r15);
 238
 239         asm("mov %%ds,%0" : "=r" (ds));
 240         asm("mov %%cs,%0" : "=r" (cs));
 241         asm("mov %%es,%0" : "=r" (es));
 242         asm("mov %%fs,%0" : "=r" (fsindex));
 243         asm("mov %%gs,%0" : "=r" (gsindex));
 244
 245         rdmsrl(MSR_FS_BASE, fs);
 246         rdmsrl(MSR_GS_BASE, gs);
 247         rdmsrl(MSR_KERNEL_GS_BASE, shadowgs);
 248
 249         printk("FS:  %016lx(%04x) GS:%016lx(%04x) knlGS:%016lx\n",
 250                fs,fsindex,gs,gsindex,shadowgs);
 251         printk("CS:  %04x DS: %04x ES: %04x\n", cs, ds, es);
 252
 253 }
 254
 255 void show_regs(struct pt_regs *regs)
 256 {
 257         printk("CPU %d:", smp_processor_id());
 258         __show_regs(regs);
 259         show_trace(&regs->rsp);
 260 }
 261
 262 /*
 263  * Free current thread data structures etc..
 264  */
 265 void exit_thread(void)
 266 {
 267         struct task_struct *me = current;
 268         struct thread_struct *t = &me->thread;
 269
 270         if (me->thread.io_bitmap_ptr) {
 271 #ifndef CONFIG_X86_NO_TSS
 272                 struct tss_struct *tss = &per_cpu(init_tss, get_cpu());
 273 #endif
 274 #ifdef CONFIG_XEN
 275                 struct physdev_set_iobitmap iobmp_op = { 0 };
 276 #endif
 277
 278                 kfree(t->io_bitmap_ptr);
 279                 t->io_bitmap_ptr = NULL;
 280                 /*
 281                  * Careful, clear this in the TSS too:
 282                  */
 283 #ifndef CONFIG_X86_NO_TSS
 284                 memset(tss->io_bitmap, 0xff, t->io_bitmap_max);
 285                 put_cpu();
 286 #endif
 287 #ifdef CONFIG_XEN
 288                 HYPERVISOR_physdev_op(PHYSDEVOP_set_iobitmap, &iobmp_op);
 289 #endif
 290                 t->io_bitmap_max = 0;
 291         }
 292 }
 293
 294 void load_gs_index(unsigned gs)
 295 {
 296         HYPERVISOR_set_segment_base(SEGBASE_GS_USER_SEL, gs);
 297 }
 298
 299 void flush_thread(void)
 300 {
 301         struct task_struct *tsk = current;
 302         struct thread_info *t = current_thread_info();
 303
 304         if (t->flags & _TIF_ABI_PENDING)
 305                 t->flags ^= (_TIF_ABI_PENDING | _TIF_IA32);
 306
 307         tsk->thread.debugreg0 = 0;
 308         tsk->thread.debugreg1 = 0;
 309         tsk->thread.debugreg2 = 0;
 310         tsk->thread.debugreg3 = 0;
 311         tsk->thread.debugreg6 = 0;
 312         tsk->thread.debugreg7 = 0;
 313         memset(tsk->thread.tls_array, 0, sizeof(tsk->thread.tls_array));
 314         /*
 315          * Forget coprocessor state..
 316          */
 317         clear_fpu(tsk);
 318         clear_used_math();
 319 }
 320
 321 void release_thread(struct task_struct *dead_task)
 322 {
 323         if (dead_task->mm) {
 324                 if (dead_task->mm->context.size) {
 325                         printk("WARNING: dead process %8s still has LDT? <%p/%d>\n",
 326                                         dead_task->comm,
 327                                         dead_task->mm->context.ldt,
 328                                         dead_task->mm->context.size);
 329                         BUG();
 330                 }
 331         }
 332 }
 333
 334 static inline void set_32bit_tls(struct task_struct *t, int tls, u32 addr)
 335 {
 336         struct user_desc ud = {
 337                 .base_addr = addr,
 338                 .limit = 0xfffff,
 339                 .contents = (3 << 3), /* user */
 340                 .seg_32bit = 1,
 341                 .limit_in_pages = 1,
 342                 .useable = 1,
 343         };
 344         struct n_desc_struct *desc = (void *)t->thread.tls_array;
 345         desc += tls;
 346         desc->a = LDT_entry_a(&ud);
 347         desc->b = LDT_entry_b(&ud);
 348 }
 349
 350 static inline u32 read_32bit_tls(struct task_struct *t, int tls)
 351 {
 352         struct desc_struct *desc = (void *)t->thread.tls_array;
 353         desc += tls;
 354         return desc->base0 |
 355                 (((u32)desc->base1) << 16) |
 356                 (((u32)desc->base2) << 24);
 357 }
 358
 359 /*
 360  * This gets called before we allocate a new thread and copy
 361  * the current task into it.
 362  */
 363 void prepare_to_copy(struct task_struct *tsk)
 364 {
 365         unlazy_fpu(tsk);
 366 }
 367
 368 int copy_thread(int nr, unsigned long clone_flags, unsigned long rsp,
 369                 unsigned long unused,
 370         struct task_struct * p, struct pt_regs * regs)
 371 {
 372         int err;
 373         struct pt_regs * childregs;
 374         struct task_struct *me = current;
 375
 376         childregs = ((struct pt_regs *)
 377                         (THREAD_SIZE + task_stack_page(p))) - 1;
 378         *childregs = *regs;
 379
 380         childregs->rax = 0;
 381         childregs->rsp = rsp;
 382         if (rsp == ~0UL)
 383                 childregs->rsp = (unsigned long)childregs;
 384
 385         p->thread.rsp = (unsigned long) childregs;
 386         p->thread.rsp0 = (unsigned long) (childregs+1);
 387         p->thread.userrsp = me->thread.userrsp;
 388
 389         set_tsk_thread_flag(p, TIF_FORK);
 390
 391         p->thread.fs = me->thread.fs;
 392         p->thread.gs = me->thread.gs;
 393
 394         asm("mov %%gs,%0" : "=m" (p->thread.gsindex));
 395         asm("mov %%fs,%0" : "=m" (p->thread.fsindex));
 396         asm("mov %%es,%0" : "=m" (p->thread.es));
 397         asm("mov %%ds,%0" : "=m" (p->thread.ds));
 398
 399         if (unlikely(me->thread.io_bitmap_ptr != NULL)) {
 400                 p->thread.io_bitmap_ptr = kmalloc(IO_BITMAP_BYTES, GFP_KERNEL);
 401                 if (!p->thread.io_bitmap_ptr) {
 402                         p->thread.io_bitmap_max = 0;
 403                         return -ENOMEM;
 404                 }
 405                 memcpy(p->thread.io_bitmap_ptr, me->thread.io_bitmap_ptr,
 406                                 IO_BITMAP_BYTES);
 407         }
 408
 409         /*
 410          * Set a new TLS for the child thread?
 411          */
 412         if (clone_flags & CLONE_SETTLS) {
 413 #ifdef CONFIG_IA32_EMULATION
 414                 if (test_thread_flag(TIF_IA32))
 415                         err = ia32_child_tls(p, childregs);
 416                 else
 417 #endif
 418                         err = do_arch_prctl(p, ARCH_SET_FS, childregs->r8);
 419                 if (err)
 420                         goto out;
 421         }
 422         p->thread.iopl = current->thread.iopl;
 423
 424         err = 0;
 425 out:
 426         if (err && p->thread.io_bitmap_ptr) {
 427                 kfree(p->thread.io_bitmap_ptr);
 428                 p->thread.io_bitmap_max = 0;
 429         }
 430         return err;
 431 }
 432
 433 static inline void __save_init_fpu( struct task_struct *tsk )
 434 {
 435         asm volatile( "rex64 ; fxsave %0 ; fnclex"
 436                       : "=m" (tsk->thread.i387.fxsave));
 437         tsk->thread_info->status &= ~TS_USEDFPU;
 438 }
 439
 440 /*
 441  *      switch_to(x,y) should switch tasks from x to y.
 442  *
 443  * This could still be optimized:
 444  * - fold all the options into a flag word and test it with a single test.
 445  * - could test fs/gs bitsliced
 446  *
 447  * Kprobes not supported here. Set the probe on schedule instead.
 448  */
 449 __kprobes struct task_struct *
 450 __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
 451 {
 452         struct thread_struct *prev = &prev_p->thread,
 453                                  *next = &next_p->thread;
 454         int cpu = smp_processor_id();
 455 #ifndef CONFIG_X86_NO_TSS
 456         struct tss_struct *tss = &per_cpu(init_tss, cpu);
 457 #endif
 458         struct physdev_set_iopl iopl_op;
 459         struct physdev_set_iobitmap iobmp_op;
 460         multicall_entry_t _mcl[8], *mcl = _mcl;
 461
 462         /*
 463          * This is basically '__unlazy_fpu', except that we queue a
 464          * multicall to indicate FPU task switch, rather than
 465          * synchronously trapping to Xen.
 466          */
 467         if (prev_p->thread_info->status & TS_USEDFPU) {
 468                 __save_init_fpu(prev_p); /* _not_ save_init_fpu() */
 469                 mcl->op      = __HYPERVISOR_fpu_taskswitch;
 470                 mcl->args[0] = 1;
 471                 mcl++;
 472         }
 473
 474         /*
 475          * Reload esp0, LDT and the page table pointer:
 476          */
 477         mcl->op      = __HYPERVISOR_stack_switch;
 478         mcl->args[0] = __KERNEL_DS;
 479         mcl->args[1] = next->rsp0;
 480         mcl++;
 481
 482         /*
 483          * Load the per-thread Thread-Local Storage descriptor.
 484          * This is load_TLS(next, cpu) with multicalls.
 485          */
 486 #define C(i) do {                                                       \
 487         if (unlikely(next->tls_array[i] != prev->tls_array[i])) {       \
 488                 mcl->op      = __HYPERVISOR_update_descriptor;          \
 489                 mcl->args[0] = virt_to_machine(                         \
 490                         &cpu_gdt(cpu)[GDT_ENTRY_TLS_MIN + i]);          \
 491                 mcl->args[1] = next->tls_array[i];                      \
 492                 mcl++;                                                  \
 493         }                                                               \
 494 } while (0)
 495         C(0); C(1); C(2);
 496 #undef C
 497
 498         if (unlikely(prev->iopl != next->iopl)) {
 499                 iopl_op.iopl = (next->iopl == 0) ? 1 : next->iopl;
 500                 mcl->op      = __HYPERVISOR_physdev_op;
 501                 mcl->args[0] = PHYSDEVOP_set_iopl;
 502                 mcl->args[1] = (unsigned long)&iopl_op;
 503                 mcl++;
 504         }
 505
 506         if (unlikely(prev->io_bitmap_ptr || next->io_bitmap_ptr)) {
 507                 iobmp_op.bitmap   = (char *)next->io_bitmap_ptr;
 508                 iobmp_op.nr_ports = next->io_bitmap_ptr ? IO_BITMAP_BITS : 0;
 509                 mcl->op      = __HYPERVISOR_physdev_op;
 510                 mcl->args[0] = PHYSDEVOP_set_iobitmap;
 511                 mcl->args[1] = (unsigned long)&iobmp_op;
 512                 mcl++;
 513         }
 514
 515         (void)HYPERVISOR_multicall(_mcl, mcl - _mcl);
 516         /*
 517          * Switch DS and ES.
 518          * This won't pick up thread selector changes, but I guess that is ok.
 519          */
 520         if (unlikely(next->es))
 521                 loadsegment(es, next->es);
 522
 523         if (unlikely(next->ds))
 524                 loadsegment(ds, next->ds);
 525
 526         /*
 527          * Switch FS and GS.
 528          */
 529         if (unlikely(next->fsindex))
 530                 loadsegment(fs, next->fsindex);
 531
 532         if (next->fs)
 533                 HYPERVISOR_set_segment_base(SEGBASE_FS, next->fs);
 534
 535         if (unlikely(next->gsindex))
 536                 load_gs_index(next->gsindex);
 537
 538         if (next->gs)
 539                 HYPERVISOR_set_segment_base(SEGBASE_GS_USER, next->gs);
 540
 541         /*
 542          * Switch the PDA.
 543          */
 544         prev->userrsp = read_pda(oldrsp);
 545         write_pda(oldrsp, next->userrsp);
 546         write_pda(pcurrent, next_p);
 547         write_pda(kernelstack,
 548                   task_stack_page(next_p) + THREAD_SIZE - PDA_STACKOFFSET);
 549
 550         /*
 551          * Now maybe reload the debug registers
 552          */
 553         if (unlikely(next->debugreg7)) {
 554                 set_debugreg(next->debugreg0, 0);
 555                 set_debugreg(next->debugreg1, 1);
 556                 set_debugreg(next->debugreg2, 2);
 557                 set_debugreg(next->debugreg3, 3);
 558                 /* no 4 and 5 */
 559                 set_debugreg(next->debugreg6, 6);
 560                 set_debugreg(next->debugreg7, 7);
 561         }
 562
 563         return prev_p;
 564 }
 565
 566 /*
 567  * sys_execve() executes a new program.
 568  */
 569 asmlinkage
 570 long sys_execve(char __user *name, char __user * __user *argv,
 571                 char __user * __user *envp, struct pt_regs regs)
 572 {
 573         long error;
 574         char * filename;
 575
 576         filename = getname(name);
 577         error = PTR_ERR(filename);
 578         if (IS_ERR(filename))
 579                 return error;
 580         error = do_execve(filename, argv, envp, &regs);
 581         if (error == 0) {
 582                 task_lock(current);
 583                 current->ptrace &= ~PT_DTRACE;
 584                 task_unlock(current);
 585         }
 586         putname(filename);
 587         return error;
 588 }
 589
 590 void set_personality_64bit(void)
 591 {
 592         /* inherit personality from parent */
 593
 594         /* Make sure to be in 64bit mode */
 595         clear_thread_flag(TIF_IA32);
 596 }
 597
 598 asmlinkage long sys_fork(struct pt_regs *regs)
 599 {
 600         return do_fork(SIGCHLD, regs->rsp, regs, 0, NULL, NULL);
 601 }
 602
 603 asmlinkage long
 604 sys_clone(unsigned long clone_flags, unsigned long newsp,
 605           void __user *parent_tid, void __user *child_tid, struct pt_regs *regs)
 606 {
 607         if (!newsp)
 608                 newsp = regs->rsp;
 609         return do_fork(clone_flags, newsp, regs, 0, parent_tid, child_tid);
 610 }
 611
 612 /*
 613  * This is trivial, and on the face of it looks like it
 614  * could equally well be done in user mode.
 615  *
 616  * Not so, for quite unobvious reasons - register pressure.
 617  * In user mode vfork() cannot have a stack frame, and if
 618  * done by calling the "clone()" system call directly, you
 619  * do not have enough call-clobbered registers to hold all
 620  * the information you need.
 621  */
 622 asmlinkage long sys_vfork(struct pt_regs *regs)
 623 {
 624         return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, regs->rsp, regs, 0,
 625                     NULL, NULL);
 626 }
 627
 628 unsigned long get_wchan(struct task_struct *p)
 629 {
 630         unsigned long stack;
 631         u64 fp,rip;
 632         int count = 0;
 633
 634         if (!p || p == current || p->state==TASK_RUNNING)
 635                 return 0;
 636         stack = (unsigned long)task_stack_page(p);
 637         if (p->thread.rsp < stack || p->thread.rsp > stack+THREAD_SIZE)
 638                 return 0;
 639         fp = *(u64 *)(p->thread.rsp);
 640         do {
 641                 if (fp < (unsigned long)stack ||
 642                     fp > (unsigned long)stack+THREAD_SIZE)
 643                         return 0;
 644                 rip = *(u64 *)(fp+8);
 645                 if (!in_sched_functions(rip))
 646                         return rip;
 647                 fp = *(u64 *)fp;
 648         } while (count++ < 16);
 649         return 0;
 650 }
 651
 652 long do_arch_prctl(struct task_struct *task, int code, unsigned long addr)
 653 {
 654         int ret = 0;
 655         int doit = task == current;
 656         int cpu;
 657
 658         switch (code) {
 659         case ARCH_SET_GS:
 660                 if (addr >= TASK_SIZE_OF(task))
 661                         return -EPERM;
 662                 cpu = get_cpu();
 663                 /* handle small bases via the GDT because that's faster to
 664                    switch. */
 665                 if (addr <= 0xffffffff) {
 666                         set_32bit_tls(task, GS_TLS, addr);
 667                         if (doit) {
 668                                 load_TLS(&task->thread, cpu);
 669                                 load_gs_index(GS_TLS_SEL);
 670                         }
 671                         task->thread.gsindex = GS_TLS_SEL;
 672                         task->thread.gs = 0;
 673                 } else {
 674                         task->thread.gsindex = 0;
 675                         task->thread.gs = addr;
 676                         if (doit) {
 677                                 load_gs_index(0);
 678                                 ret = HYPERVISOR_set_segment_base(
 679                                         SEGBASE_GS_USER, addr);
 680                         }
 681                 }
 682                 put_cpu();
 683                 break;
 684         case ARCH_SET_FS:
 685                 /* Not strictly needed for fs, but do it for symmetry
 686                    with gs */
 687                 if (addr >= TASK_SIZE_OF(task))
 688                         return -EPERM;
 689                 cpu = get_cpu();
 690                 /* handle small bases via the GDT because that's faster to
 691                    switch. */
 692                 if (addr <= 0xffffffff) {
 693                         set_32bit_tls(task, FS_TLS, addr);
 694                         if (doit) {
 695                                 load_TLS(&task->thread, cpu);
 696                                 asm volatile("movl %0,%%fs" :: "r"(FS_TLS_SEL));
 697                         }
 698                         task->thread.fsindex = FS_TLS_SEL;
 699                         task->thread.fs = 0;
 700                 } else {
 701                         task->thread.fsindex = 0;
 702                         task->thread.fs = addr;
 703                         if (doit) {
 704                                 /* set the selector to 0 to not confuse
 705                                    __switch_to */
 706                                 asm volatile("movl %0,%%fs" :: "r" (0));
 707                                 ret = HYPERVISOR_set_segment_base(SEGBASE_FS,
 708                                                                   addr);
 709                         }
 710                 }
 711                 put_cpu();
 712                 break;
 713         case ARCH_GET_FS: {
 714                 unsigned long base;
 715                 if (task->thread.fsindex == FS_TLS_SEL)
 716                         base = read_32bit_tls(task, FS_TLS);
 717                 else if (doit)
 718                         rdmsrl(MSR_FS_BASE, base);
 719                 else
 720                         base = task->thread.fs;
 721                 ret = put_user(base, (unsigned long __user *)addr);
 722                 break;
 723         }
 724         case ARCH_GET_GS: {
 725                 unsigned long base;
 726                 unsigned gsindex;
 727                 if (task->thread.gsindex == GS_TLS_SEL)
 728                         base = read_32bit_tls(task, GS_TLS);
 729                 else if (doit) {
 730                         asm("movl %%gs,%0" : "=r" (gsindex));
 731                         if (gsindex)
 732                                 rdmsrl(MSR_KERNEL_GS_BASE, base);
 733                         else
 734                                 base = task->thread.gs;
 735                 }
 736                 else
 737                         base = task->thread.gs;
 738                 ret = put_user(base, (unsigned long __user *)addr);
 739                 break;
 740         }
 741
 742         default:
 743                 ret = -EINVAL;
 744                 break;
 745         }
 746
 747         return ret;
 748 }
 749
 750 long sys_arch_prctl(int code, unsigned long addr)
 751 {
 752         return do_arch_prctl(current, code, addr);
 753 }
 754
 755 /*
 756  * Capture the user space registers if the task is not running (in user space)
 757  */
 758 int dump_task_regs(struct task_struct *tsk, elf_gregset_t *regs)
 759 {
 760         struct pt_regs *pp, ptregs;
 761
 762         pp = task_pt_regs(tsk);
 763
 764         ptregs = *pp;
 765         ptregs.cs &= 0xffff;
 766         ptregs.ss &= 0xffff;
 767
 768         elf_core_copy_regs(regs, &ptregs);
 769
 770         boot_option_idle_override = 1;
 771         return 1;
 772 }
 773
 774 unsigned long arch_align_stack(unsigned long sp)
 775 {
 776         if (randomize_va_space)
 777                 sp -= get_random_int() % 8192;
 778         return sp & ~0xf;
 779 }
 780
 781 #ifndef CONFIG_SMP
 782 void _restore_vcpu(void)
 783 {
 784 }
 785 #endif