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 <linux/stackprotector.h>
  18 #include <linux/cpu.h>
  19 #include <linux/errno.h>
  20 #include <linux/sched.h>
  21 #include <linux/fs.h>
  22 #include <linux/kernel.h>
  23 #include <linux/mm.h>
  24 #include <linux/elfcore.h>
  25 #include <linux/smp.h>
  26 #include <linux/slab.h>
  27 #include <linux/user.h>
  28 #include <linux/interrupt.h>
  29 #include <linux/delay.h>
  30 #include <linux/module.h>
  31 #include <linux/ptrace.h>
  32 #include <linux/notifier.h>
  33 #include <linux/kprobes.h>
  34 #include <linux/kdebug.h>
  35 #include <linux/tick.h>
  36 #include <linux/prctl.h>
  37 #include <linux/uaccess.h>
  38 #include <linux/io.h>
  39 #include <linux/ftrace.h>
  40 #include <linux/cpuidle.h>
  41
  42 #include <asm/pgtable.h>
  43 #include <asm/system.h>
  44 #include <asm/processor.h>
  45 #include <asm/i387.h>
  46 #include <asm/mmu_context.h>
  47 #include <asm/prctl.h>
  48 #include <asm/desc.h>
  49 #include <asm/proto.h>
  50 #include <asm/ia32.h>
  51 #include <asm/idle.h>
  52 #include <asm/syscalls.h>
  53 #include <asm/debugreg.h>
  54 #include <asm/nmi.h>
  55
  56 asmlinkage extern void ret_from_fork(void);
  57
  58 DEFINE_PER_CPU(unsigned long, old_rsp);
  59 static DEFINE_PER_CPU(unsigned char, is_idle);
  60
  61 static ATOMIC_NOTIFIER_HEAD(idle_notifier);
  62
  63 void idle_notifier_register(struct notifier_block *n)
  64 {
  65         atomic_notifier_chain_register(&idle_notifier, n);
  66 }
  67 EXPORT_SYMBOL_GPL(idle_notifier_register);
  68
  69 void idle_notifier_unregister(struct notifier_block *n)
  70 {
  71         atomic_notifier_chain_unregister(&idle_notifier, n);
  72 }
  73 EXPORT_SYMBOL_GPL(idle_notifier_unregister);
  74
  75 void enter_idle(void)
  76 {
  77         percpu_write(is_idle, 1);
  78         atomic_notifier_call_chain(&idle_notifier, IDLE_START, NULL);
  79 }
  80
  81 static void __exit_idle(void)
  82 {
  83         if (x86_test_and_clear_bit_percpu(0, is_idle) == 0)
  84                 return;
  85         atomic_notifier_call_chain(&idle_notifier, IDLE_END, NULL);
  86 }
  87
  88 /* Called from interrupts to signify idle end */
  89 void exit_idle(void)
  90 {
  91         /* idle loop has pid 0 */
  92         if (current->pid)
  93                 return;
  94         __exit_idle();
  95 }
  96
  97 #ifndef CONFIG_SMP
  98 static inline void play_dead(void)
  99 {
 100         BUG();
 101 }
 102 #endif
 103
 104 /*
 105  * The idle thread. There's no useful work to be
 106  * done, so just try to conserve power and have a
 107  * low exit latency (ie sit in a loop waiting for
 108  * somebody to say that they'd like to reschedule)
 109  */
 110 void cpu_idle(void)
 111 {
 112         current_thread_info()->status |= TS_POLLING;
 113
 114         /*
 115          * If we're the non-boot CPU, nothing set the stack canary up
 116          * for us.  CPU0 already has it initialized but no harm in
 117          * doing it again.  This is a good place for updating it, as
 118          * we wont ever return from this function (so the invalid
 119          * canaries already on the stack wont ever trigger).
 120          */
 121         boot_init_stack_canary();
 122
 123         /* endless idle loop with no priority at all */
 124         while (1) {
 125                 tick_nohz_idle_enter();
 126                 while (!need_resched()) {
 127
 128                         rmb();
 129
 130                         if (cpu_is_offline(smp_processor_id()))
 131                                 play_dead();
 132                         /*
 133                          * Idle routines should keep interrupts disabled
 134                          * from here on, until they go to idle.
 135                          * Otherwise, idle callbacks can misfire.
 136                          */
 137                         local_touch_nmi();
 138                         local_irq_disable();
 139                         enter_idle();
 140                         /* Don't trace irqs off for idle */
 141                         stop_critical_timings();
 142
 143                         /* enter_idle() needs rcu for notifiers */
 144                         rcu_idle_enter();
 145
 146                         if (cpuidle_idle_call())
 147                                 pm_idle();
 148
 149                         rcu_idle_exit();
 150                         start_critical_timings();
 151
 152                         /* In many cases the interrupt that ended idle
 153                            has already called exit_idle. But some idle
 154                            loops can be woken up without interrupt. */
 155                         __exit_idle();
 156                 }
 157
 158                 tick_nohz_idle_exit();
 159                 preempt_enable_no_resched();
 160                 schedule();
 161                 preempt_disable();
 162         }
 163 }
 164
 165 /* Prints also some state that isn't saved in the pt_regs */
 166 void __show_regs(struct pt_regs *regs, int all)
 167 {
 168         unsigned long cr0 = 0L, cr2 = 0L, cr3 = 0L, cr4 = 0L, fs, gs, shadowgs;
 169         unsigned long d0, d1, d2, d3, d6, d7;
 170         unsigned int fsindex, gsindex;
 171         unsigned int ds, cs, es;
 172
 173         show_regs_common();
 174         printk(KERN_DEFAULT "RIP: %04lx:[<%016lx>] ", regs->cs & 0xffff, regs->ip);
 175         printk_address(regs->ip, 1);
 176         printk(KERN_DEFAULT "RSP: %04lx:%016lx  EFLAGS: %08lx\n", regs->ss,
 177                         regs->sp, regs->flags);
 178         printk(KERN_DEFAULT "RAX: %016lx RBX: %016lx RCX: %016lx\n",
 179                regs->ax, regs->bx, regs->cx);
 180         printk(KERN_DEFAULT "RDX: %016lx RSI: %016lx RDI: %016lx\n",
 181                regs->dx, regs->si, regs->di);
 182         printk(KERN_DEFAULT "RBP: %016lx R08: %016lx R09: %016lx\n",
 183                regs->bp, regs->r8, regs->r9);
 184         printk(KERN_DEFAULT "R10: %016lx R11: %016lx R12: %016lx\n",
 185                regs->r10, regs->r11, regs->r12);
 186         printk(KERN_DEFAULT "R13: %016lx R14: %016lx R15: %016lx\n",
 187                regs->r13, regs->r14, regs->r15);
 188
 189         asm("movl %%ds,%0" : "=r" (ds));
 190         asm("movl %%cs,%0" : "=r" (cs));
 191         asm("movl %%es,%0" : "=r" (es));
 192         asm("movl %%fs,%0" : "=r" (fsindex));
 193         asm("movl %%gs,%0" : "=r" (gsindex));
 194
 195         rdmsrl(MSR_FS_BASE, fs);
 196         rdmsrl(MSR_GS_BASE, gs);
 197         rdmsrl(MSR_KERNEL_GS_BASE, shadowgs);
 198
 199         if (!all)
 200                 return;
 201
 202         cr0 = read_cr0();
 203         cr2 = read_cr2();
 204         cr3 = read_cr3();
 205         cr4 = read_cr4();
 206
 207         printk(KERN_DEFAULT "FS:  %016lx(%04x) GS:%016lx(%04x) knlGS:%016lx\n",
 208                fs, fsindex, gs, gsindex, shadowgs);
 209         printk(KERN_DEFAULT "CS:  %04x DS: %04x ES: %04x CR0: %016lx\n", cs, ds,
 210                         es, cr0);
 211         printk(KERN_DEFAULT "CR2: %016lx CR3: %016lx CR4: %016lx\n", cr2, cr3,
 212                         cr4);
 213
 214         get_debugreg(d0, 0);
 215         get_debugreg(d1, 1);
 216         get_debugreg(d2, 2);
 217         printk(KERN_DEFAULT "DR0: %016lx DR1: %016lx DR2: %016lx\n", d0, d1, d2);
 218         get_debugreg(d3, 3);
 219         get_debugreg(d6, 6);
 220         get_debugreg(d7, 7);
 221         printk(KERN_DEFAULT "DR3: %016lx DR6: %016lx DR7: %016lx\n", d3, d6, d7);
 222 }
 223
 224 void release_thread(struct task_struct *dead_task)
 225 {
 226         if (dead_task->mm) {
 227                 if (dead_task->mm->context.size) {
 228                         printk("WARNING: dead process %8s still has LDT? <%p/%d>\n",
 229                                         dead_task->comm,
 230                                         dead_task->mm->context.ldt,
 231                                         dead_task->mm->context.size);
 232                         BUG();
 233                 }
 234         }
 235 }
 236
 237 static inline void set_32bit_tls(struct task_struct *t, int tls, u32 addr)
 238 {
 239         struct user_desc ud = {
 240                 .base_addr = addr,
 241                 .limit = 0xfffff,
 242                 .seg_32bit = 1,
 243                 .limit_in_pages = 1,
 244                 .useable = 1,
 245         };
 246         struct desc_struct *desc = t->thread.tls_array;
 247         desc += tls;
 248         fill_ldt(desc, &ud);
 249 }
 250
 251 static inline u32 read_32bit_tls(struct task_struct *t, int tls)
 252 {
 253         return get_desc_base(&t->thread.tls_array[tls]);
 254 }
 255
 256 /*
 257  * This gets called before we allocate a new thread and copy
 258  * the current task into it.
 259  */
 260 void prepare_to_copy(struct task_struct *tsk)
 261 {
 262         unlazy_fpu(tsk);
 263 }
 264
 265 int copy_thread(unsigned long clone_flags, unsigned long sp,
 266                 unsigned long unused,
 267         struct task_struct *p, struct pt_regs *regs)
 268 {
 269         int err;
 270         struct pt_regs *childregs;
 271         struct task_struct *me = current;
 272
 273         childregs = ((struct pt_regs *)
 274                         (THREAD_SIZE + task_stack_page(p))) - 1;
 275         *childregs = *regs;
 276
 277         childregs->ax = 0;
 278         if (user_mode(regs))
 279                 childregs->sp = sp;
 280         else
 281                 childregs->sp = (unsigned long)childregs;
 282
 283         p->thread.sp = (unsigned long) childregs;
 284         p->thread.sp0 = (unsigned long) (childregs+1);
 285         p->thread.usersp = me->thread.usersp;
 286
 287         set_tsk_thread_flag(p, TIF_FORK);
 288
 289         p->fpu_counter = 0;
 290         p->thread.io_bitmap_ptr = NULL;
 291
 292         savesegment(gs, p->thread.gsindex);
 293         p->thread.gs = p->thread.gsindex ? 0 : me->thread.gs;
 294         savesegment(fs, p->thread.fsindex);
 295         p->thread.fs = p->thread.fsindex ? 0 : me->thread.fs;
 296         savesegment(es, p->thread.es);
 297         savesegment(ds, p->thread.ds);
 298
 299         err = -ENOMEM;
 300         memset(p->thread.ptrace_bps, 0, sizeof(p->thread.ptrace_bps));
 301
 302         if (unlikely(test_tsk_thread_flag(me, TIF_IO_BITMAP))) {
 303                 p->thread.io_bitmap_ptr = kmemdup(me->thread.io_bitmap_ptr,
 304                                                   IO_BITMAP_BYTES, GFP_KERNEL);
 305                 if (!p->thread.io_bitmap_ptr) {
 306                         p->thread.io_bitmap_max = 0;
 307                         return -ENOMEM;
 308                 }
 309                 set_tsk_thread_flag(p, TIF_IO_BITMAP);
 310         }
 311
 312         /*
 313          * Set a new TLS for the child thread?
 314          */
 315         if (clone_flags & CLONE_SETTLS) {
 316 #ifdef CONFIG_IA32_EMULATION
 317                 if (test_thread_flag(TIF_IA32))
 318                         err = do_set_thread_area(p, -1,
 319                                 (struct user_desc __user *)childregs->si, 0);
 320                 else
 321 #endif
 322                         err = do_arch_prctl(p, ARCH_SET_FS, childregs->r8);
 323                 if (err)
 324                         goto out;
 325         }
 326         err = 0;
 327 out:
 328         if (err && p->thread.io_bitmap_ptr) {
 329                 kfree(p->thread.io_bitmap_ptr);
 330                 p->thread.io_bitmap_max = 0;
 331         }
 332
 333         return err;
 334 }
 335
 336 static void
 337 start_thread_common(struct pt_regs *regs, unsigned long new_ip,
 338                     unsigned long new_sp,
 339                     unsigned int _cs, unsigned int _ss, unsigned int _ds)
 340 {
 341         loadsegment(fs, 0);
 342         loadsegment(es, _ds);
 343         loadsegment(ds, _ds);
 344         load_gs_index(0);
 345         regs->ip                = new_ip;
 346         regs->sp                = new_sp;
 347         percpu_write(old_rsp, new_sp);
 348         regs->cs                = _cs;
 349         regs->ss                = _ss;
 350         regs->flags             = X86_EFLAGS_IF;
 351         /*
 352          * Free the old FP and other extended state
 353          */
 354         free_thread_xstate(current);
 355 }
 356
 357 void
 358 start_thread(struct pt_regs *regs, unsigned long new_ip, unsigned long new_sp)
 359 {
 360         start_thread_common(regs, new_ip, new_sp,
 361                             __USER_CS, __USER_DS, 0);
 362 }
 363
 364 #ifdef CONFIG_IA32_EMULATION
 365 void start_thread_ia32(struct pt_regs *regs, u32 new_ip, u32 new_sp)
 366 {
 367         start_thread_common(regs, new_ip, new_sp,
 368                             __USER32_CS, __USER32_DS, __USER32_DS);
 369 }
 370 #endif
 371
 372 /*
 373  *      switch_to(x,y) should switch tasks from x to y.
 374  *
 375  * This could still be optimized:
 376  * - fold all the options into a flag word and test it with a single test.
 377  * - could test fs/gs bitsliced
 378  *
 379  * Kprobes not supported here. Set the probe on schedule instead.
 380  * Function graph tracer not supported too.
 381  */
 382 __notrace_funcgraph struct task_struct *
 383 __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
 384 {
 385         struct thread_struct *prev = &prev_p->thread;
 386         struct thread_struct *next = &next_p->thread;
 387         int cpu = smp_processor_id();
 388         struct tss_struct *tss = &per_cpu(init_tss, cpu);
 389         unsigned fsindex, gsindex;
 390         fpu_switch_t fpu;
 391
 392         fpu = switch_fpu_prepare(prev_p, next_p, cpu);
 393
 394         /*
 395          * Reload esp0, LDT and the page table pointer:
 396          */
 397         load_sp0(tss, next);
 398
 399         /*
 400          * Switch DS and ES.
 401          * This won't pick up thread selector changes, but I guess that is ok.
 402          */
 403         savesegment(es, prev->es);
 404         if (unlikely(next->es | prev->es))
 405                 loadsegment(es, next->es);
 406
 407         savesegment(ds, prev->ds);
 408         if (unlikely(next->ds | prev->ds))
 409                 loadsegment(ds, next->ds);
 410
 411
 412         /* We must save %fs and %gs before load_TLS() because
 413          * %fs and %gs may be cleared by load_TLS().
 414          *
 415          * (e.g. xen_load_tls())
 416          */
 417         savesegment(fs, fsindex);
 418         savesegment(gs, gsindex);
 419
 420         load_TLS(next, cpu);
 421
 422         /*
 423          * Leave lazy mode, flushing any hypercalls made here.
 424          * This must be done before restoring TLS segments so
 425          * the GDT and LDT are properly updated, and must be
 426          * done before math_state_restore, so the TS bit is up
 427          * to date.
 428          */
 429         arch_end_context_switch(next_p);
 430
 431         /*
 432          * Switch FS and GS.
 433          *
 434          * Segment register != 0 always requires a reload.  Also
 435          * reload when it has changed.  When prev process used 64bit
 436          * base always reload to avoid an information leak.
 437          */
 438         if (unlikely(fsindex | next->fsindex | prev->fs)) {
 439                 loadsegment(fs, next->fsindex);
 440                 /*
 441                  * Check if the user used a selector != 0; if yes
 442                  *  clear 64bit base, since overloaded base is always
 443                  *  mapped to the Null selector
 444                  */
 445                 if (fsindex)
 446                         prev->fs = 0;
 447         }
 448         /* when next process has a 64bit base use it */
 449         if (next->fs)
 450                 wrmsrl(MSR_FS_BASE, next->fs);
 451         prev->fsindex = fsindex;
 452
 453         if (unlikely(gsindex | next->gsindex | prev->gs)) {
 454                 load_gs_index(next->gsindex);
 455                 if (gsindex)
 456                         prev->gs = 0;
 457         }
 458         if (next->gs)
 459                 wrmsrl(MSR_KERNEL_GS_BASE, next->gs);
 460         prev->gsindex = gsindex;
 461
 462         switch_fpu_finish(next_p, fpu);
 463
 464         /*
 465          * Switch the PDA and FPU contexts.
 466          */
 467         prev->usersp = percpu_read(old_rsp);
 468         percpu_write(old_rsp, next->usersp);
 469         percpu_write(current_task, next_p);
 470
 471         percpu_write(kernel_stack,
 472                   (unsigned long)task_stack_page(next_p) +
 473                   THREAD_SIZE - KERNEL_STACK_OFFSET);
 474
 475         /*
 476          * Now maybe reload the debug registers and handle I/O bitmaps
 477          */
 478         if (unlikely(task_thread_info(next_p)->flags & _TIF_WORK_CTXSW_NEXT ||
 479                      task_thread_info(prev_p)->flags & _TIF_WORK_CTXSW_PREV))
 480                 __switch_to_xtra(prev_p, next_p, tss);
 481
 482         return prev_p;
 483 }
 484
 485 void set_personality_64bit(void)
 486 {
 487         /* inherit personality from parent */
 488
 489         /* Make sure to be in 64bit mode */
 490         clear_thread_flag(TIF_IA32);
 491
 492         /* Ensure the corresponding mm is not marked. */
 493         if (current->mm)
 494                 current->mm->context.ia32_compat = 0;
 495
 496         /* TBD: overwrites user setup. Should have two bits.
 497            But 64bit processes have always behaved this way,
 498            so it's not too bad. The main problem is just that
 499            32bit childs are affected again. */
 500         current->personality &= ~READ_IMPLIES_EXEC;
 501 }
 502
 503 void set_personality_ia32(void)
 504 {
 505         /* inherit personality from parent */
 506
 507         /* Make sure to be in 32bit mode */
 508         set_thread_flag(TIF_IA32);
 509         current->personality |= force_personality32;
 510
 511         /* Mark the associated mm as containing 32-bit tasks. */
 512         if (current->mm)
 513                 current->mm->context.ia32_compat = 1;
 514
 515         /* Prepare the first "return" to user space */
 516         current_thread_info()->status |= TS_COMPAT;
 517 }
 518
 519 unsigned long get_wchan(struct task_struct *p)
 520 {
 521         unsigned long stack;
 522         u64 fp, ip;
 523         int count = 0;
 524
 525         if (!p || p == current || p->state == TASK_RUNNING)
 526                 return 0;
 527         stack = (unsigned long)task_stack_page(p);
 528         if (p->thread.sp < stack || p->thread.sp >= stack+THREAD_SIZE)
 529                 return 0;
 530         fp = *(u64 *)(p->thread.sp);
 531         do {
 532                 if (fp < (unsigned long)stack ||
 533                     fp >= (unsigned long)stack+THREAD_SIZE)
 534                         return 0;
 535                 ip = *(u64 *)(fp+8);
 536                 if (!in_sched_functions(ip))
 537                         return ip;
 538                 fp = *(u64 *)fp;
 539         } while (count++ < 16);
 540         return 0;
 541 }
 542
 543 long do_arch_prctl(struct task_struct *task, int code, unsigned long addr)
 544 {
 545         int ret = 0;
 546         int doit = task == current;
 547         int cpu;
 548
 549         switch (code) {
 550         case ARCH_SET_GS:
 551                 if (addr >= TASK_SIZE_OF(task))
 552                         return -EPERM;
 553                 cpu = get_cpu();
 554                 /* handle small bases via the GDT because that's faster to
 555                    switch. */
 556                 if (addr <= 0xffffffff) {
 557                         set_32bit_tls(task, GS_TLS, addr);
 558                         if (doit) {
 559                                 load_TLS(&task->thread, cpu);
 560                                 load_gs_index(GS_TLS_SEL);
 561                         }
 562                         task->thread.gsindex = GS_TLS_SEL;
 563                         task->thread.gs = 0;
 564                 } else {
 565                         task->thread.gsindex = 0;
 566                         task->thread.gs = addr;
 567                         if (doit) {
 568                                 load_gs_index(0);
 569                                 ret = checking_wrmsrl(MSR_KERNEL_GS_BASE, addr);
 570                         }
 571                 }
 572                 put_cpu();
 573                 break;
 574         case ARCH_SET_FS:
 575                 /* Not strictly needed for fs, but do it for symmetry
 576                    with gs */
 577                 if (addr >= TASK_SIZE_OF(task))
 578                         return -EPERM;
 579                 cpu = get_cpu();
 580                 /* handle small bases via the GDT because that's faster to
 581                    switch. */
 582                 if (addr <= 0xffffffff) {
 583                         set_32bit_tls(task, FS_TLS, addr);
 584                         if (doit) {
 585                                 load_TLS(&task->thread, cpu);
 586                                 loadsegment(fs, FS_TLS_SEL);
 587                         }
 588                         task->thread.fsindex = FS_TLS_SEL;
 589                         task->thread.fs = 0;
 590                 } else {
 591                         task->thread.fsindex = 0;
 592                         task->thread.fs = addr;
 593                         if (doit) {
 594                                 /* set the selector to 0 to not confuse
 595                                    __switch_to */
 596                                 loadsegment(fs, 0);
 597                                 ret = checking_wrmsrl(MSR_FS_BASE, addr);
 598                         }
 599                 }
 600                 put_cpu();
 601                 break;
 602         case ARCH_GET_FS: {
 603                 unsigned long base;
 604                 if (task->thread.fsindex == FS_TLS_SEL)
 605                         base = read_32bit_tls(task, FS_TLS);
 606                 else if (doit)
 607                         rdmsrl(MSR_FS_BASE, base);
 608                 else
 609                         base = task->thread.fs;
 610                 ret = put_user(base, (unsigned long __user *)addr);
 611                 break;
 612         }
 613         case ARCH_GET_GS: {
 614                 unsigned long base;
 615                 unsigned gsindex;
 616                 if (task->thread.gsindex == GS_TLS_SEL)
 617                         base = read_32bit_tls(task, GS_TLS);
 618                 else if (doit) {
 619                         savesegment(gs, gsindex);
 620                         if (gsindex)
 621                                 rdmsrl(MSR_KERNEL_GS_BASE, base);
 622                         else
 623                                 base = task->thread.gs;
 624                 } else
 625                         base = task->thread.gs;
 626                 ret = put_user(base, (unsigned long __user *)addr);
 627                 break;
 628         }
 629
 630         default:
 631                 ret = -EINVAL;
 632                 break;
 633         }
 634
 635         return ret;
 636 }
 637
 638 long sys_arch_prctl(int code, unsigned long addr)
 639 {
 640         return do_arch_prctl(current, code, addr);
 641 }
 642
 643 unsigned long KSTK_ESP(struct task_struct *task)
 644 {
 645         return (test_tsk_thread_flag(task, TIF_IA32)) ?
 646                         (task_pt_regs(task)->sp) : ((task)->thread.usersp);
 647 }