arch/x86/kernel/process_64.c

   1 /*
   2  *  Copyright (C) 1995  Linus Torvalds
   3  *
   4  *  Pentium III FXSR, SSE support
   5  *      Gareth Hughes <gareth@valinux.com>, May 2000
   6  *
   7  *  X86-64 port
   8  *      Andi Kleen.
   9  *
  10  *      CPU hotplug support - ashok.raj@intel.com
  11  */
  12
  13 /*
  14  * This file handles the architecture-dependent parts of process handling..
  15  */
  16
  17 #include <stdarg.h>
  18
  19 #include <linux/cpu.h>
  20 #include <linux/errno.h>
  21 #include <linux/sched.h>
  22 #include <linux/kernel.h>
  23 #include <linux/mm.h>
  24 #include <linux/fs.h>
  25 #include <linux/elfcore.h>
  26 #include <linux/smp.h>
  27 #include <linux/slab.h>
  28 #include <linux/user.h>
  29 #include <linux/module.h>
  30 #include <linux/a.out.h>
  31 #include <linux/interrupt.h>
  32 #include <linux/delay.h>
  33 #include <linux/ptrace.h>
  34 #include <linux/utsname.h>
  35 #include <linux/random.h>
  36 #include <linux/notifier.h>
  37 #include <linux/kprobes.h>
  38 #include <linux/kdebug.h>
  39 #include <linux/tick.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/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 void enter_idle(void)
  84 {
  85         write_pda(isidle, 1);
  86         atomic_notifier_call_chain(&idle_notifier, IDLE_START, NULL);
  87 }
  88
  89 static void __exit_idle(void)
  90 {
  91         if (test_and_clear_bit_pda(0, isidle) == 0)
  92                 return;
  93         atomic_notifier_call_chain(&idle_notifier, IDLE_END, NULL);
  94 }
  95
  96 /* Called from interrupts to signify idle end */
  97 void exit_idle(void)
  98 {
  99         /* idle loop has pid 0 */
 100         if (current->pid)
 101                 return;
 102         __exit_idle();
 103 }
 104
 105 /*
 106  * We use this if we don't have any better
 107  * idle routine..
 108  */
 109 static void default_idle(void)
 110 {
 111         current_thread_info()->status &= ~TS_POLLING;
 112         /*
 113          * TS_POLLING-cleared state must be visible before we
 114          * test NEED_RESCHED:
 115          */
 116         smp_mb();
 117         local_irq_disable();
 118         if (!need_resched()) {
 119                 /* Enables interrupts one instruction before HLT.
 120                    x86 special cases this so there is no race. */
 121                 safe_halt();
 122         } else
 123                 local_irq_enable();
 124         current_thread_info()->status |= TS_POLLING;
 125 }
 126
 127 /*
 128  * On SMP it's slightly faster (but much more power-consuming!)
 129  * to poll the ->need_resched flag instead of waiting for the
 130  * cross-CPU IPI to arrive. Use this option with caution.
 131  */
 132 static void poll_idle (void)
 133 {
 134         local_irq_enable();
 135         cpu_relax();
 136 }
 137
 138 void cpu_idle_wait(void)
 139 {
 140         unsigned int cpu, this_cpu = get_cpu();
 141         cpumask_t map, tmp = current->cpus_allowed;
 142
 143         set_cpus_allowed(current, cpumask_of_cpu(this_cpu));
 144         put_cpu();
 145
 146         cpus_clear(map);
 147         for_each_online_cpu(cpu) {
 148                 per_cpu(cpu_idle_state, cpu) = 1;
 149                 cpu_set(cpu, map);
 150         }
 151
 152         __get_cpu_var(cpu_idle_state) = 0;
 153
 154         wmb();
 155         do {
 156                 ssleep(1);
 157                 for_each_online_cpu(cpu) {
 158                         if (cpu_isset(cpu, map) &&
 159                                         !per_cpu(cpu_idle_state, cpu))
 160                                 cpu_clear(cpu, map);
 161                 }
 162                 cpus_and(map, map, cpu_online_map);
 163         } while (!cpus_empty(map));
 164
 165         set_cpus_allowed(current, tmp);
 166 }
 167 EXPORT_SYMBOL_GPL(cpu_idle_wait);
 168
 169 #ifdef CONFIG_HOTPLUG_CPU
 170 DECLARE_PER_CPU(int, cpu_state);
 171
 172 #include <asm/nmi.h>
 173 /* We halt the CPU with physical CPU hotplug */
 174 static inline void play_dead(void)
 175 {
 176         idle_task_exit();
 177         wbinvd();
 178         mb();
 179         /* Ack it */
 180         __get_cpu_var(cpu_state) = CPU_DEAD;
 181
 182         local_irq_disable();
 183         while (1)
 184                 halt();
 185 }
 186 #else
 187 static inline void play_dead(void)
 188 {
 189         BUG();
 190 }
 191 #endif /* CONFIG_HOTPLUG_CPU */
 192
 193 /*
 194  * The idle thread. There's no useful work to be
 195  * done, so just try to conserve power and have a
 196  * low exit latency (ie sit in a loop waiting for
 197  * somebody to say that they'd like to reschedule)
 198  */
 199 void cpu_idle (void)
 200 {
 201         current_thread_info()->status |= TS_POLLING;
 202         /* endless idle loop with no priority at all */
 203         while (1) {
 204                 while (!need_resched()) {
 205                         void (*idle)(void);
 206
 207                         if (__get_cpu_var(cpu_idle_state))
 208                                 __get_cpu_var(cpu_idle_state) = 0;
 209
 210                         tick_nohz_stop_sched_tick();
 211
 212                         rmb();
 213                         idle = pm_idle;
 214                         if (!idle)
 215                                 idle = default_idle;
 216                         if (cpu_is_offline(smp_processor_id()))
 217                                 play_dead();
 218                         /*
 219                          * Idle routines should keep interrupts disabled
 220                          * from here on, until they go to idle.
 221                          * Otherwise, idle callbacks can misfire.
 222                          */
 223                         local_irq_disable();
 224                         enter_idle();
 225                         idle();
 226                         /* In many cases the interrupt that ended idle
 227                            has already called exit_idle. But some idle
 228                            loops can be woken up without interrupt. */
 229                         __exit_idle();
 230                 }
 231
 232                 tick_nohz_restart_sched_tick();
 233                 preempt_enable_no_resched();
 234                 schedule();
 235                 preempt_disable();
 236         }
 237 }
 238
 239 /*
 240  * This uses new MONITOR/MWAIT instructions on P4 processors with PNI,
 241  * which can obviate IPI to trigger checking of need_resched.
 242  * We execute MONITOR against need_resched and enter optimized wait state
 243  * through MWAIT. Whenever someone changes need_resched, we would be woken
 244  * up from MWAIT (without an IPI).
 245  *
 246  * New with Core Duo processors, MWAIT can take some hints based on CPU
 247  * capability.
 248  */
 249 void mwait_idle_with_hints(unsigned long eax, unsigned long ecx)
 250 {
 251         if (!need_resched()) {
 252                 __monitor((void *)&current_thread_info()->flags, 0, 0);
 253                 smp_mb();
 254                 if (!need_resched())
 255                         __mwait(eax, ecx);
 256         }
 257 }
 258
 259 /* Default MONITOR/MWAIT with no hints, used for default C1 state */
 260 static void mwait_idle(void)
 261 {
 262         if (!need_resched()) {
 263                 __monitor((void *)&current_thread_info()->flags, 0, 0);
 264                 smp_mb();
 265                 if (!need_resched())
 266                         __sti_mwait(0, 0);
 267                 else
 268                         local_irq_enable();
 269         } else {
 270                 local_irq_enable();
 271         }
 272 }
 273
 274 void __cpuinit select_idle_routine(const struct cpuinfo_x86 *c)
 275 {
 276         static int printed;
 277         if (cpu_has(c, X86_FEATURE_MWAIT)) {
 278                 /*
 279                  * Skip, if setup has overridden idle.
 280                  * One CPU supports mwait => All CPUs supports mwait
 281                  */
 282                 if (!pm_idle) {
 283                         if (!printed) {
 284                                 printk(KERN_INFO "using mwait in idle threads.\n");
 285                                 printed = 1;
 286                         }
 287                         pm_idle = mwait_idle;
 288                 }
 289         }
 290 }
 291
 292 static int __init idle_setup (char *str)
 293 {
 294         if (!strcmp(str, "poll")) {
 295                 printk("using polling idle threads.\n");
 296                 pm_idle = poll_idle;
 297         } else if (!strcmp(str, "mwait"))
 298                 force_mwait = 1;
 299         else
 300                 return -1;
 301
 302         boot_option_idle_override = 1;
 303         return 0;
 304 }
 305 early_param("idle", idle_setup);
 306
 307 /* Prints also some state that isn't saved in the pt_regs */
 308 void __show_regs(struct pt_regs * regs)
 309 {
 310         unsigned long cr0 = 0L, cr2 = 0L, cr3 = 0L, cr4 = 0L, fs, gs, shadowgs;
 311         unsigned long d0, d1, d2, d3, d6, d7;
 312         unsigned int fsindex,gsindex;
 313         unsigned int ds,cs,es;
 314
 315         printk("\n");
 316         print_modules();
 317         printk("Pid: %d, comm: %.20s %s %s %.*s\n",
 318                 current->pid, current->comm, print_tainted(),
 319                 init_utsname()->release,
 320                 (int)strcspn(init_utsname()->version, " "),
 321                 init_utsname()->version);
 322         printk("RIP: %04lx:[<%016lx>] ", regs->cs & 0xffff, regs->rip);
 323         printk_address(regs->rip);
 324         printk("RSP: %04lx:%016lx  EFLAGS: %08lx\n", regs->ss, regs->rsp,
 325                 regs->eflags);
 326         printk("RAX: %016lx RBX: %016lx RCX: %016lx\n",
 327                regs->rax, regs->rbx, regs->rcx);
 328         printk("RDX: %016lx RSI: %016lx RDI: %016lx\n",
 329                regs->rdx, regs->rsi, regs->rdi);
 330         printk("RBP: %016lx R08: %016lx R09: %016lx\n",
 331                regs->rbp, regs->r8, regs->r9);
 332         printk("R10: %016lx R11: %016lx R12: %016lx\n",
 333                regs->r10, regs->r11, regs->r12);
 334         printk("R13: %016lx R14: %016lx R15: %016lx\n",
 335                regs->r13, regs->r14, regs->r15);
 336
 337         asm("movl %%ds,%0" : "=r" (ds));
 338         asm("movl %%cs,%0" : "=r" (cs));
 339         asm("movl %%es,%0" : "=r" (es));
 340         asm("movl %%fs,%0" : "=r" (fsindex));
 341         asm("movl %%gs,%0" : "=r" (gsindex));
 342
 343         rdmsrl(MSR_FS_BASE, fs);
 344         rdmsrl(MSR_GS_BASE, gs);
 345         rdmsrl(MSR_KERNEL_GS_BASE, shadowgs);
 346
 347         cr0 = read_cr0();
 348         cr2 = read_cr2();
 349         cr3 = read_cr3();
 350         cr4 = read_cr4();
 351
 352         printk("FS:  %016lx(%04x) GS:%016lx(%04x) knlGS:%016lx\n",
 353                fs,fsindex,gs,gsindex,shadowgs);
 354         printk("CS:  %04x DS: %04x ES: %04x CR0: %016lx\n", cs, ds, es, cr0);
 355         printk("CR2: %016lx CR3: %016lx CR4: %016lx\n", cr2, cr3, cr4);
 356
 357         get_debugreg(d0, 0);
 358         get_debugreg(d1, 1);
 359         get_debugreg(d2, 2);
 360         printk("DR0: %016lx DR1: %016lx DR2: %016lx\n", d0, d1, d2);
 361         get_debugreg(d3, 3);
 362         get_debugreg(d6, 6);
 363         get_debugreg(d7, 7);
 364         printk("DR3: %016lx DR6: %016lx DR7: %016lx\n", d3, d6, d7);
 365 }
 366
 367 void show_regs(struct pt_regs *regs)
 368 {
 369         printk("CPU %d:", smp_processor_id());
 370         __show_regs(regs);
 371         show_trace(NULL, regs, (void *)(regs + 1));
 372 }
 373
 374 /*
 375  * Free current thread data structures etc..
 376  */
 377 void exit_thread(void)
 378 {
 379         struct task_struct *me = current;
 380         struct thread_struct *t = &me->thread;
 381
 382         if (me->thread.io_bitmap_ptr) {
 383                 struct tss_struct *tss = &per_cpu(init_tss, get_cpu());
 384
 385                 kfree(t->io_bitmap_ptr);
 386                 t->io_bitmap_ptr = NULL;
 387                 clear_thread_flag(TIF_IO_BITMAP);
 388                 /*
 389                  * Careful, clear this in the TSS too:
 390                  */
 391                 memset(tss->io_bitmap, 0xff, t->io_bitmap_max);
 392                 t->io_bitmap_max = 0;
 393                 put_cpu();
 394         }
 395 }
 396
 397 void flush_thread(void)
 398 {
 399         struct task_struct *tsk = current;
 400
 401         if (test_tsk_thread_flag(tsk, TIF_ABI_PENDING)) {
 402                 clear_tsk_thread_flag(tsk, TIF_ABI_PENDING);
 403                 if (test_tsk_thread_flag(tsk, TIF_IA32)) {
 404                         clear_tsk_thread_flag(tsk, TIF_IA32);
 405                 } else {
 406                         set_tsk_thread_flag(tsk, TIF_IA32);
 407                         current_thread_info()->status |= TS_COMPAT;
 408                 }
 409         }
 410         clear_tsk_thread_flag(tsk, TIF_DEBUG);
 411
 412         tsk->thread.debugreg0 = 0;
 413         tsk->thread.debugreg1 = 0;
 414         tsk->thread.debugreg2 = 0;
 415         tsk->thread.debugreg3 = 0;
 416         tsk->thread.debugreg6 = 0;
 417         tsk->thread.debugreg7 = 0;
 418         memset(tsk->thread.tls_array, 0, sizeof(tsk->thread.tls_array));
 419         /*
 420          * Forget coprocessor state..
 421          */
 422         clear_fpu(tsk);
 423         clear_used_math();
 424 }
 425
 426 void release_thread(struct task_struct *dead_task)
 427 {
 428         if (dead_task->mm) {
 429                 if (dead_task->mm->context.size) {
 430                         printk("WARNING: dead process %8s still has LDT? <%p/%d>\n",
 431                                         dead_task->comm,
 432                                         dead_task->mm->context.ldt,
 433                                         dead_task->mm->context.size);
 434                         BUG();
 435                 }
 436         }
 437 }
 438
 439 static inline void set_32bit_tls(struct task_struct *t, int tls, u32 addr)
 440 {
 441         struct user_desc ud = {
 442                 .base_addr = addr,
 443                 .limit = 0xfffff,
 444                 .seg_32bit = 1,
 445                 .limit_in_pages = 1,
 446                 .useable = 1,
 447         };
 448         struct n_desc_struct *desc = (void *)t->thread.tls_array;
 449         desc += tls;
 450         desc->a = LDT_entry_a(&ud);
 451         desc->b = LDT_entry_b(&ud);
 452 }
 453
 454 static inline u32 read_32bit_tls(struct task_struct *t, int tls)
 455 {
 456         struct desc_struct *desc = (void *)t->thread.tls_array;
 457         desc += tls;
 458         return desc->base0 |
 459                 (((u32)desc->base1) << 16) |
 460                 (((u32)desc->base2) << 24);
 461 }
 462
 463 /*
 464  * This gets called before we allocate a new thread and copy
 465  * the current task into it.
 466  */
 467 void prepare_to_copy(struct task_struct *tsk)
 468 {
 469         unlazy_fpu(tsk);
 470 }
 471
 472 int copy_thread(int nr, unsigned long clone_flags, unsigned long rsp,
 473                 unsigned long unused,
 474         struct task_struct * p, struct pt_regs * regs)
 475 {
 476         int err;
 477         struct pt_regs * childregs;
 478         struct task_struct *me = current;
 479
 480         childregs = ((struct pt_regs *)
 481                         (THREAD_SIZE + task_stack_page(p))) - 1;
 482         *childregs = *regs;
 483
 484         childregs->rax = 0;
 485         childregs->rsp = rsp;
 486         if (rsp == ~0UL)
 487                 childregs->rsp = (unsigned long)childregs;
 488
 489         p->thread.rsp = (unsigned long) childregs;
 490         p->thread.rsp0 = (unsigned long) (childregs+1);
 491         p->thread.userrsp = me->thread.userrsp;
 492
 493         set_tsk_thread_flag(p, TIF_FORK);
 494
 495         p->thread.fs = me->thread.fs;
 496         p->thread.gs = me->thread.gs;
 497
 498         asm("mov %%gs,%0" : "=m" (p->thread.gsindex));
 499         asm("mov %%fs,%0" : "=m" (p->thread.fsindex));
 500         asm("mov %%es,%0" : "=m" (p->thread.es));
 501         asm("mov %%ds,%0" : "=m" (p->thread.ds));
 502
 503         if (unlikely(test_tsk_thread_flag(me, TIF_IO_BITMAP))) {
 504                 p->thread.io_bitmap_ptr = kmalloc(IO_BITMAP_BYTES, GFP_KERNEL);
 505                 if (!p->thread.io_bitmap_ptr) {
 506                         p->thread.io_bitmap_max = 0;
 507                         return -ENOMEM;
 508                 }
 509                 memcpy(p->thread.io_bitmap_ptr, me->thread.io_bitmap_ptr,
 510                                 IO_BITMAP_BYTES);
 511                 set_tsk_thread_flag(p, TIF_IO_BITMAP);
 512         }
 513
 514         /*
 515          * Set a new TLS for the child thread?
 516          */
 517         if (clone_flags & CLONE_SETTLS) {
 518 #ifdef CONFIG_IA32_EMULATION
 519                 if (test_thread_flag(TIF_IA32))
 520                         err = ia32_child_tls(p, childregs);
 521                 else
 522 #endif
 523                         err = do_arch_prctl(p, ARCH_SET_FS, childregs->r8);
 524                 if (err)
 525                         goto out;
 526         }
 527         err = 0;
 528 out:
 529         if (err && p->thread.io_bitmap_ptr) {
 530                 kfree(p->thread.io_bitmap_ptr);
 531                 p->thread.io_bitmap_max = 0;
 532         }
 533         return err;
 534 }
 535
 536 /*
 537  * This special macro can be used to load a debugging register
 538  */
 539 #define loaddebug(thread,r) set_debugreg(thread->debugreg ## r, r)
 540
 541 static inline void __switch_to_xtra(struct task_struct *prev_p,
 542                                     struct task_struct *next_p,
 543                                     struct tss_struct *tss)
 544 {
 545         struct thread_struct *prev, *next;
 546
 547         prev = &prev_p->thread,
 548         next = &next_p->thread;
 549
 550         if (test_tsk_thread_flag(next_p, TIF_DEBUG)) {
 551                 loaddebug(next, 0);
 552                 loaddebug(next, 1);
 553                 loaddebug(next, 2);
 554                 loaddebug(next, 3);
 555                 /* no 4 and 5 */
 556                 loaddebug(next, 6);
 557                 loaddebug(next, 7);
 558         }
 559
 560         if (test_tsk_thread_flag(next_p, TIF_IO_BITMAP)) {
 561                 /*
 562                  * Copy the relevant range of the IO bitmap.
 563                  * Normally this is 128 bytes or less:
 564                  */
 565                 memcpy(tss->io_bitmap, next->io_bitmap_ptr,
 566                        max(prev->io_bitmap_max, next->io_bitmap_max));
 567         } else if (test_tsk_thread_flag(prev_p, TIF_IO_BITMAP)) {
 568                 /*
 569                  * Clear any possible leftover bits:
 570                  */
 571                 memset(tss->io_bitmap, 0xff, prev->io_bitmap_max);
 572         }
 573 }
 574
 575 /*
 576  *      switch_to(x,y) should switch tasks from x to y.
 577  *
 578  * This could still be optimized:
 579  * - fold all the options into a flag word and test it with a single test.
 580  * - could test fs/gs bitsliced
 581  *
 582  * Kprobes not supported here. Set the probe on schedule instead.
 583  */
 584 __kprobes struct task_struct *
 585 __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
 586 {
 587         struct thread_struct *prev = &prev_p->thread,
 588                                  *next = &next_p->thread;
 589         int cpu = smp_processor_id();
 590         struct tss_struct *tss = &per_cpu(init_tss, cpu);
 591
 592         /* we're going to use this soon, after a few expensive things */
 593         if (next_p->fpu_counter>5)
 594                 prefetch(&next->i387.fxsave);
 595
 596         /*
 597          * Reload esp0, LDT and the page table pointer:
 598          */
 599         tss->rsp0 = next->rsp0;
 600
 601         /*
 602          * Switch DS and ES.
 603          * This won't pick up thread selector changes, but I guess that is ok.
 604          */
 605         asm volatile("mov %%es,%0" : "=m" (prev->es));
 606         if (unlikely(next->es | prev->es))
 607                 loadsegment(es, next->es);
 608
 609         asm volatile ("mov %%ds,%0" : "=m" (prev->ds));
 610         if (unlikely(next->ds | prev->ds))
 611                 loadsegment(ds, next->ds);
 612
 613         load_TLS(next, cpu);
 614
 615         /*
 616          * Switch FS and GS.
 617          */
 618         {
 619                 unsigned fsindex;
 620                 asm volatile("movl %%fs,%0" : "=r" (fsindex));
 621                 /* segment register != 0 always requires a reload.
 622                    also reload when it has changed.
 623                    when prev process used 64bit base always reload
 624                    to avoid an information leak. */
 625                 if (unlikely(fsindex | next->fsindex | prev->fs)) {
 626                         loadsegment(fs, next->fsindex);
 627                         /* check if the user used a selector != 0
 628                          * if yes clear 64bit base, since overloaded base
 629                          * is always mapped to the Null selector
 630                          */
 631                         if (fsindex)
 632                         prev->fs = 0;
 633                 }
 634                 /* when next process has a 64bit base use it */
 635                 if (next->fs)
 636                         wrmsrl(MSR_FS_BASE, next->fs);
 637                 prev->fsindex = fsindex;
 638         }
 639         {
 640                 unsigned gsindex;
 641                 asm volatile("movl %%gs,%0" : "=r" (gsindex));
 642                 if (unlikely(gsindex | next->gsindex | prev->gs)) {
 643                         load_gs_index(next->gsindex);
 644                         if (gsindex)
 645                         prev->gs = 0;
 646                 }
 647                 if (next->gs)
 648                         wrmsrl(MSR_KERNEL_GS_BASE, next->gs);
 649                 prev->gsindex = gsindex;
 650         }
 651
 652         /* Must be after DS reload */
 653         unlazy_fpu(prev_p);
 654
 655         /*
 656          * Switch the PDA and FPU contexts.
 657          */
 658         prev->userrsp = read_pda(oldrsp);
 659         write_pda(oldrsp, next->userrsp);
 660         write_pda(pcurrent, next_p);
 661
 662         write_pda(kernelstack,
 663         (unsigned long)task_stack_page(next_p) + THREAD_SIZE - PDA_STACKOFFSET);
 664 #ifdef CONFIG_CC_STACKPROTECTOR
 665         write_pda(stack_canary, next_p->stack_canary);
 666         /*
 667          * Build time only check to make sure the stack_canary is at
 668          * offset 40 in the pda; this is a gcc ABI requirement
 669          */
 670         BUILD_BUG_ON(offsetof(struct x8664_pda, stack_canary) != 40);
 671 #endif
 672
 673         /*
 674          * Now maybe reload the debug registers and handle I/O bitmaps
 675          */
 676         if (unlikely((task_thread_info(next_p)->flags & _TIF_WORK_CTXSW))
 677             || test_tsk_thread_flag(prev_p, TIF_IO_BITMAP))
 678                 __switch_to_xtra(prev_p, next_p, tss);
 679
 680         /* If the task has used fpu the last 5 timeslices, just do a full
 681          * restore of the math state immediately to avoid the trap; the
 682          * chances of needing FPU soon are obviously high now
 683          */
 684         if (next_p->fpu_counter>5)
 685                 math_state_restore();
 686         return prev_p;
 687 }
 688
 689 /*
 690  * sys_execve() executes a new program.
 691  */
 692 asmlinkage
 693 long sys_execve(char __user *name, char __user * __user *argv,
 694                 char __user * __user *envp, struct pt_regs regs)
 695 {
 696         long error;
 697         char * filename;
 698
 699         filename = getname(name);
 700         error = PTR_ERR(filename);
 701         if (IS_ERR(filename))
 702                 return error;
 703         error = do_execve(filename, argv, envp, &regs);
 704         if (error == 0) {
 705                 task_lock(current);
 706                 current->ptrace &= ~PT_DTRACE;
 707                 task_unlock(current);
 708         }
 709         putname(filename);
 710         return error;
 711 }
 712
 713 void set_personality_64bit(void)
 714 {
 715         /* inherit personality from parent */
 716
 717         /* Make sure to be in 64bit mode */
 718         clear_thread_flag(TIF_IA32);
 719
 720         /* TBD: overwrites user setup. Should have two bits.
 721            But 64bit processes have always behaved this way,
 722            so it's not too bad. The main problem is just that
 723            32bit childs are affected again. */
 724         current->personality &= ~READ_IMPLIES_EXEC;
 725 }
 726
 727 asmlinkage long sys_fork(struct pt_regs *regs)
 728 {
 729         return do_fork(SIGCHLD, regs->rsp, regs, 0, NULL, NULL);
 730 }
 731
 732 asmlinkage long
 733 sys_clone(unsigned long clone_flags, unsigned long newsp,
 734           void __user *parent_tid, void __user *child_tid, struct pt_regs *regs)
 735 {
 736         if (!newsp)
 737                 newsp = regs->rsp;
 738         return do_fork(clone_flags, newsp, regs, 0, parent_tid, child_tid);
 739 }
 740
 741 /*
 742  * This is trivial, and on the face of it looks like it
 743  * could equally well be done in user mode.
 744  *
 745  * Not so, for quite unobvious reasons - register pressure.
 746  * In user mode vfork() cannot have a stack frame, and if
 747  * done by calling the "clone()" system call directly, you
 748  * do not have enough call-clobbered registers to hold all
 749  * the information you need.
 750  */
 751 asmlinkage long sys_vfork(struct pt_regs *regs)
 752 {
 753         return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, regs->rsp, regs, 0,
 754                     NULL, NULL);
 755 }
 756
 757 unsigned long get_wchan(struct task_struct *p)
 758 {
 759         unsigned long stack;
 760         u64 fp,rip;
 761         int count = 0;
 762
 763         if (!p || p == current || p->state==TASK_RUNNING)
 764                 return 0;
 765         stack = (unsigned long)task_stack_page(p);
 766         if (p->thread.rsp < stack || p->thread.rsp > stack+THREAD_SIZE)
 767                 return 0;
 768         fp = *(u64 *)(p->thread.rsp);
 769         do {
 770                 if (fp < (unsigned long)stack ||
 771                     fp > (unsigned long)stack+THREAD_SIZE)
 772                         return 0;
 773                 rip = *(u64 *)(fp+8);
 774                 if (!in_sched_functions(rip))
 775                         return rip;
 776                 fp = *(u64 *)fp;
 777         } while (count++ < 16);
 778         return 0;
 779 }
 780
 781 long do_arch_prctl(struct task_struct *task, int code, unsigned long addr)
 782 {
 783         int ret = 0;
 784         int doit = task == current;
 785         int cpu;
 786
 787         switch (code) {
 788         case ARCH_SET_GS:
 789                 if (addr >= TASK_SIZE_OF(task))
 790                         return -EPERM;
 791                 cpu = get_cpu();
 792                 /* handle small bases via the GDT because that's faster to
 793                    switch. */
 794                 if (addr <= 0xffffffff) {
 795                         set_32bit_tls(task, GS_TLS, addr);
 796                         if (doit) {
 797                                 load_TLS(&task->thread, cpu);
 798                                 load_gs_index(GS_TLS_SEL);
 799                         }
 800                         task->thread.gsindex = GS_TLS_SEL;
 801                         task->thread.gs = 0;
 802                 } else {
 803                         task->thread.gsindex = 0;
 804                         task->thread.gs = addr;
 805                         if (doit) {
 806                                 load_gs_index(0);
 807                                 ret = checking_wrmsrl(MSR_KERNEL_GS_BASE, addr);
 808                         }
 809                 }
 810                 put_cpu();
 811                 break;
 812         case ARCH_SET_FS:
 813                 /* Not strictly needed for fs, but do it for symmetry
 814                    with gs */
 815                 if (addr >= TASK_SIZE_OF(task))
 816                         return -EPERM;
 817                 cpu = get_cpu();
 818                 /* handle small bases via the GDT because that's faster to
 819                    switch. */
 820                 if (addr <= 0xffffffff) {
 821                         set_32bit_tls(task, FS_TLS, addr);
 822                         if (doit) {
 823                                 load_TLS(&task->thread, cpu);
 824                                 asm volatile("movl %0,%%fs" :: "r"(FS_TLS_SEL));
 825                         }
 826                         task->thread.fsindex = FS_TLS_SEL;
 827                         task->thread.fs = 0;
 828                 } else {
 829                         task->thread.fsindex = 0;
 830                         task->thread.fs = addr;
 831                         if (doit) {
 832                                 /* set the selector to 0 to not confuse
 833                                    __switch_to */
 834                                 asm volatile("movl %0,%%fs" :: "r" (0));
 835                                 ret = checking_wrmsrl(MSR_FS_BASE, addr);
 836                         }
 837                 }
 838                 put_cpu();
 839                 break;
 840         case ARCH_GET_FS: {
 841                 unsigned long base;
 842                 if (task->thread.fsindex == FS_TLS_SEL)
 843                         base = read_32bit_tls(task, FS_TLS);
 844                 else if (doit)
 845                         rdmsrl(MSR_FS_BASE, base);
 846                 else
 847                         base = task->thread.fs;
 848                 ret = put_user(base, (unsigned long __user *)addr);
 849                 break;
 850         }
 851         case ARCH_GET_GS: {
 852                 unsigned long base;
 853                 unsigned gsindex;
 854                 if (task->thread.gsindex == GS_TLS_SEL)
 855                         base = read_32bit_tls(task, GS_TLS);
 856                 else if (doit) {
 857                         asm("movl %%gs,%0" : "=r" (gsindex));
 858                         if (gsindex)
 859                                 rdmsrl(MSR_KERNEL_GS_BASE, base);
 860                         else
 861                                 base = task->thread.gs;
 862                 }
 863                 else
 864                         base = task->thread.gs;
 865                 ret = put_user(base, (unsigned long __user *)addr);
 866                 break;
 867         }
 868
 869         default:
 870                 ret = -EINVAL;
 871                 break;
 872         }
 873
 874         return ret;
 875 }
 876
 877 long sys_arch_prctl(int code, unsigned long addr)
 878 {
 879         return do_arch_prctl(current, code, addr);
 880 }
 881
 882 /*
 883  * Capture the user space registers if the task is not running (in user space)
 884  */
 885 int dump_task_regs(struct task_struct *tsk, elf_gregset_t *regs)
 886 {
 887         struct pt_regs *pp, ptregs;
 888
 889         pp = task_pt_regs(tsk);
 890
 891         ptregs = *pp;
 892         ptregs.cs &= 0xffff;
 893         ptregs.ss &= 0xffff;
 894
 895         elf_core_copy_regs(regs, &ptregs);
 896
 897         return 1;
 898 }
 899
 900 unsigned long arch_align_stack(unsigned long sp)
 901 {
 902         if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
 903                 sp -= get_random_int() % 8192;
 904         return sp & ~0xf;
 905 }