arch/x86/kernel/process.c

   1 #include <linux/errno.h>
   2 #include <linux/kernel.h>
   3 #include <linux/mm.h>
   4 #include <linux/smp.h>
   5 #include <linux/prctl.h>
   6 #include <linux/slab.h>
   7 #include <linux/sched.h>
   8 #include <linux/module.h>
   9 #include <linux/pm.h>
  10 #include <linux/clockchips.h>
  11 #include <linux/random.h>
  12 #include <linux/user-return-notifier.h>
  13 #include <linux/dmi.h>
  14 #include <linux/utsname.h>
  15 #include <trace/events/power.h>
  16 #include <linux/hw_breakpoint.h>
  17 #include <asm/system.h>
  18 #include <asm/apic.h>
  19 #include <asm/syscalls.h>
  20 #include <asm/idle.h>
  21 #include <asm/uaccess.h>
  22 #include <asm/i387.h>
  23 #include <asm/debugreg.h>
  24
  25 unsigned long idle_halt;
  26 EXPORT_SYMBOL(idle_halt);
  27 unsigned long idle_nomwait;
  28 EXPORT_SYMBOL(idle_nomwait);
  29
  30 struct kmem_cache *task_xstate_cachep;
  31 EXPORT_SYMBOL_GPL(task_xstate_cachep);
  32
  33 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
  34 {
  35         int ret;
  36
  37         *dst = *src;
  38         if (fpu_allocated(&src->thread.fpu)) {
  39                 memset(&dst->thread.fpu, 0, sizeof(dst->thread.fpu));
  40                 ret = fpu_alloc(&dst->thread.fpu);
  41                 if (ret)
  42                         return ret;
  43                 fpu_copy(&dst->thread.fpu, &src->thread.fpu);
  44         }
  45         return 0;
  46 }
  47
  48 void free_thread_xstate(struct task_struct *tsk)
  49 {
  50         fpu_free(&tsk->thread.fpu);
  51 }
  52
  53 void free_thread_info(struct thread_info *ti)
  54 {
  55         free_thread_xstate(ti->task);
  56         free_pages((unsigned long)ti, get_order(THREAD_SIZE));
  57 }
  58
  59 void arch_task_cache_init(void)
  60 {
  61         task_xstate_cachep =
  62                 kmem_cache_create("task_xstate", xstate_size,
  63                                   __alignof__(union thread_xstate),
  64                                   SLAB_PANIC | SLAB_NOTRACK, NULL);
  65 }
  66
  67 /*
  68  * Free current thread data structures etc..
  69  */
  70 void exit_thread(void)
  71 {
  72         struct task_struct *me = current;
  73         struct thread_struct *t = &me->thread;
  74         unsigned long *bp = t->io_bitmap_ptr;
  75
  76         if (bp) {
  77                 struct tss_struct *tss = &per_cpu(init_tss, get_cpu());
  78
  79                 t->io_bitmap_ptr = NULL;
  80                 clear_thread_flag(TIF_IO_BITMAP);
  81                 /*
  82                  * Careful, clear this in the TSS too:
  83                  */
  84                 memset(tss->io_bitmap, 0xff, t->io_bitmap_max);
  85                 t->io_bitmap_max = 0;
  86                 put_cpu();
  87                 kfree(bp);
  88         }
  89 }
  90
  91 void show_regs(struct pt_regs *regs)
  92 {
  93         show_registers(regs);
  94         show_trace(NULL, regs, (unsigned long *)kernel_stack_pointer(regs),
  95                    regs->bp);
  96 }
  97
  98 void show_regs_common(void)
  99 {
 100         const char *board, *product;
 101
 102         board = dmi_get_system_info(DMI_BOARD_NAME);
 103         if (!board)
 104                 board = "";
 105         product = dmi_get_system_info(DMI_PRODUCT_NAME);
 106         if (!product)
 107                 product = "";
 108
 109         printk(KERN_CONT "\n");
 110         printk(KERN_DEFAULT "Pid: %d, comm: %.20s %s %s %.*s %s/%s\n",
 111                 current->pid, current->comm, print_tainted(),
 112                 init_utsname()->release,
 113                 (int)strcspn(init_utsname()->version, " "),
 114                 init_utsname()->version, board, product);
 115 }
 116
 117 void flush_thread(void)
 118 {
 119         struct task_struct *tsk = current;
 120
 121         flush_ptrace_hw_breakpoint(tsk);
 122         memset(tsk->thread.tls_array, 0, sizeof(tsk->thread.tls_array));
 123         /*
 124          * Forget coprocessor state..
 125          */
 126         tsk->fpu_counter = 0;
 127         clear_fpu(tsk);
 128         clear_used_math();
 129 }
 130
 131 static void hard_disable_TSC(void)
 132 {
 133         write_cr4(read_cr4() | X86_CR4_TSD);
 134 }
 135
 136 void disable_TSC(void)
 137 {
 138         preempt_disable();
 139         if (!test_and_set_thread_flag(TIF_NOTSC))
 140                 /*
 141                  * Must flip the CPU state synchronously with
 142                  * TIF_NOTSC in the current running context.
 143                  */
 144                 hard_disable_TSC();
 145         preempt_enable();
 146 }
 147
 148 static void hard_enable_TSC(void)
 149 {
 150         write_cr4(read_cr4() & ~X86_CR4_TSD);
 151 }
 152
 153 static void enable_TSC(void)
 154 {
 155         preempt_disable();
 156         if (test_and_clear_thread_flag(TIF_NOTSC))
 157                 /*
 158                  * Must flip the CPU state synchronously with
 159                  * TIF_NOTSC in the current running context.
 160                  */
 161                 hard_enable_TSC();
 162         preempt_enable();
 163 }
 164
 165 int get_tsc_mode(unsigned long adr)
 166 {
 167         unsigned int val;
 168
 169         if (test_thread_flag(TIF_NOTSC))
 170                 val = PR_TSC_SIGSEGV;
 171         else
 172                 val = PR_TSC_ENABLE;
 173
 174         return put_user(val, (unsigned int __user *)adr);
 175 }
 176
 177 int set_tsc_mode(unsigned int val)
 178 {
 179         if (val == PR_TSC_SIGSEGV)
 180                 disable_TSC();
 181         else if (val == PR_TSC_ENABLE)
 182                 enable_TSC();
 183         else
 184                 return -EINVAL;
 185
 186         return 0;
 187 }
 188
 189 void __switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p,
 190                       struct tss_struct *tss)
 191 {
 192         struct thread_struct *prev, *next;
 193
 194         prev = &prev_p->thread;
 195         next = &next_p->thread;
 196
 197         if (test_tsk_thread_flag(prev_p, TIF_BLOCKSTEP) ^
 198             test_tsk_thread_flag(next_p, TIF_BLOCKSTEP)) {
 199                 unsigned long debugctl = get_debugctlmsr();
 200
 201                 debugctl &= ~DEBUGCTLMSR_BTF;
 202                 if (test_tsk_thread_flag(next_p, TIF_BLOCKSTEP))
 203                         debugctl |= DEBUGCTLMSR_BTF;
 204
 205                 update_debugctlmsr(debugctl);
 206         }
 207
 208         if (test_tsk_thread_flag(prev_p, TIF_NOTSC) ^
 209             test_tsk_thread_flag(next_p, TIF_NOTSC)) {
 210                 /* prev and next are different */
 211                 if (test_tsk_thread_flag(next_p, TIF_NOTSC))
 212                         hard_disable_TSC();
 213                 else
 214                         hard_enable_TSC();
 215         }
 216
 217         if (test_tsk_thread_flag(next_p, TIF_IO_BITMAP)) {
 218                 /*
 219                  * Copy the relevant range of the IO bitmap.
 220                  * Normally this is 128 bytes or less:
 221                  */
 222                 memcpy(tss->io_bitmap, next->io_bitmap_ptr,
 223                        max(prev->io_bitmap_max, next->io_bitmap_max));
 224         } else if (test_tsk_thread_flag(prev_p, TIF_IO_BITMAP)) {
 225                 /*
 226                  * Clear any possible leftover bits:
 227                  */
 228                 memset(tss->io_bitmap, 0xff, prev->io_bitmap_max);
 229         }
 230         propagate_user_return_notify(prev_p, next_p);
 231 }
 232
 233 int sys_fork(struct pt_regs *regs)
 234 {
 235         return do_fork(SIGCHLD, regs->sp, regs, 0, NULL, NULL);
 236 }
 237
 238 /*
 239  * This is trivial, and on the face of it looks like it
 240  * could equally well be done in user mode.
 241  *
 242  * Not so, for quite unobvious reasons - register pressure.
 243  * In user mode vfork() cannot have a stack frame, and if
 244  * done by calling the "clone()" system call directly, you
 245  * do not have enough call-clobbered registers to hold all
 246  * the information you need.
 247  */
 248 int sys_vfork(struct pt_regs *regs)
 249 {
 250         return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, regs->sp, regs, 0,
 251                        NULL, NULL);
 252 }
 253
 254 long
 255 sys_clone(unsigned long clone_flags, unsigned long newsp,
 256           void __user *parent_tid, void __user *child_tid, struct pt_regs *regs)
 257 {
 258         if (!newsp)
 259                 newsp = regs->sp;
 260         return do_fork(clone_flags, newsp, regs, 0, parent_tid, child_tid);
 261 }
 262
 263 /*
 264  * This gets run with %si containing the
 265  * function to call, and %di containing
 266  * the "args".
 267  */
 268 extern void kernel_thread_helper(void);
 269
 270 /*
 271  * Create a kernel thread
 272  */
 273 int kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
 274 {
 275         struct pt_regs regs;
 276
 277         memset(&regs, 0, sizeof(regs));
 278
 279         regs.si = (unsigned long) fn;
 280         regs.di = (unsigned long) arg;
 281
 282 #ifdef CONFIG_X86_32
 283         regs.ds = __USER_DS;
 284         regs.es = __USER_DS;
 285         regs.fs = __KERNEL_PERCPU;
 286         regs.gs = __KERNEL_STACK_CANARY;
 287 #else
 288         regs.ss = __KERNEL_DS;
 289 #endif
 290
 291         regs.orig_ax = -1;
 292         regs.ip = (unsigned long) kernel_thread_helper;
 293         regs.cs = __KERNEL_CS | get_kernel_rpl();
 294         regs.flags = X86_EFLAGS_IF | 0x2;
 295
 296         /* Ok, create the new process.. */
 297         return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, &regs, 0, NULL, NULL);
 298 }
 299 EXPORT_SYMBOL(kernel_thread);
 300
 301 /*
 302  * sys_execve() executes a new program.
 303  */
 304 long sys_execve(const char __user *name,
 305                 const char __user *const __user *argv,
 306                 const char __user *const __user *envp, struct pt_regs *regs)
 307 {
 308         long error;
 309         char *filename;
 310
 311         filename = getname(name);
 312         error = PTR_ERR(filename);
 313         if (IS_ERR(filename))
 314                 return error;
 315         error = do_execve(filename, argv, envp, regs);
 316
 317 #ifdef CONFIG_X86_32
 318         if (error == 0) {
 319                 /* Make sure we don't return using sysenter.. */
 320                 set_thread_flag(TIF_IRET);
 321         }
 322 #endif
 323
 324         putname(filename);
 325         return error;
 326 }
 327
 328 /*
 329  * Idle related variables and functions
 330  */
 331 unsigned long boot_option_idle_override = 0;
 332 EXPORT_SYMBOL(boot_option_idle_override);
 333
 334 /*
 335  * Powermanagement idle function, if any..
 336  */
 337 void (*pm_idle)(void);
 338 EXPORT_SYMBOL(pm_idle);
 339
 340 #ifdef CONFIG_X86_32
 341 /*
 342  * This halt magic was a workaround for ancient floppy DMA
 343  * wreckage. It should be safe to remove.
 344  */
 345 static int hlt_counter;
 346 void disable_hlt(void)
 347 {
 348         hlt_counter++;
 349 }
 350 EXPORT_SYMBOL(disable_hlt);
 351
 352 void enable_hlt(void)
 353 {
 354         hlt_counter--;
 355 }
 356 EXPORT_SYMBOL(enable_hlt);
 357
 358 static inline int hlt_use_halt(void)
 359 {
 360         return (!hlt_counter && boot_cpu_data.hlt_works_ok);
 361 }
 362 #else
 363 static inline int hlt_use_halt(void)
 364 {
 365         return 1;
 366 }
 367 #endif
 368
 369 /*
 370  * We use this if we don't have any better
 371  * idle routine..
 372  */
 373 void default_idle(void)
 374 {
 375         if (hlt_use_halt()) {
 376                 trace_power_start(POWER_CSTATE, 1, smp_processor_id());
 377                 current_thread_info()->status &= ~TS_POLLING;
 378                 /*
 379                  * TS_POLLING-cleared state must be visible before we
 380                  * test NEED_RESCHED:
 381                  */
 382                 smp_mb();
 383
 384                 if (!need_resched())
 385                         safe_halt();    /* enables interrupts racelessly */
 386                 else
 387                         local_irq_enable();
 388                 current_thread_info()->status |= TS_POLLING;
 389         } else {
 390                 local_irq_enable();
 391                 /* loop is done by the caller */
 392                 cpu_relax();
 393         }
 394 }
 395 #ifdef CONFIG_APM_MODULE
 396 EXPORT_SYMBOL(default_idle);
 397 #endif
 398
 399 void stop_this_cpu(void *dummy)
 400 {
 401         local_irq_disable();
 402         /*
 403          * Remove this CPU:
 404          */
 405         set_cpu_online(smp_processor_id(), false);
 406         disable_local_APIC();
 407
 408         for (;;) {
 409                 if (hlt_works(smp_processor_id()))
 410                         halt();
 411         }
 412 }
 413
 414 static void do_nothing(void *unused)
 415 {
 416 }
 417
 418 /*
 419  * cpu_idle_wait - Used to ensure that all the CPUs discard old value of
 420  * pm_idle and update to new pm_idle value. Required while changing pm_idle
 421  * handler on SMP systems.
 422  *
 423  * Caller must have changed pm_idle to the new value before the call. Old
 424  * pm_idle value will not be used by any CPU after the return of this function.
 425  */
 426 void cpu_idle_wait(void)
 427 {
 428         smp_mb();
 429         /* kick all the CPUs so that they exit out of pm_idle */
 430         smp_call_function(do_nothing, NULL, 1);
 431 }
 432 EXPORT_SYMBOL_GPL(cpu_idle_wait);
 433
 434 /*
 435  * This uses new MONITOR/MWAIT instructions on P4 processors with PNI,
 436  * which can obviate IPI to trigger checking of need_resched.
 437  * We execute MONITOR against need_resched and enter optimized wait state
 438  * through MWAIT. Whenever someone changes need_resched, we would be woken
 439  * up from MWAIT (without an IPI).
 440  *
 441  * New with Core Duo processors, MWAIT can take some hints based on CPU
 442  * capability.
 443  */
 444 void mwait_idle_with_hints(unsigned long ax, unsigned long cx)
 445 {
 446         trace_power_start(POWER_CSTATE, (ax>>4)+1, smp_processor_id());
 447         if (!need_resched()) {
 448                 if (cpu_has(__this_cpu_ptr(&cpu_info), X86_FEATURE_CLFLUSH_MONITOR))
 449                         clflush((void *)&current_thread_info()->flags);
 450
 451                 __monitor((void *)&current_thread_info()->flags, 0, 0);
 452                 smp_mb();
 453                 if (!need_resched())
 454                         __mwait(ax, cx);
 455         }
 456 }
 457
 458 /* Default MONITOR/MWAIT with no hints, used for default C1 state */
 459 static void mwait_idle(void)
 460 {
 461         if (!need_resched()) {
 462                 trace_power_start(POWER_CSTATE, 1, smp_processor_id());
 463                 if (cpu_has(__this_cpu_ptr(&cpu_info), X86_FEATURE_CLFLUSH_MONITOR))
 464                         clflush((void *)&current_thread_info()->flags);
 465
 466                 __monitor((void *)&current_thread_info()->flags, 0, 0);
 467                 smp_mb();
 468                 if (!need_resched())
 469                         __sti_mwait(0, 0);
 470                 else
 471                         local_irq_enable();
 472         } else
 473                 local_irq_enable();
 474 }
 475
 476 /*
 477  * On SMP it's slightly faster (but much more power-consuming!)
 478  * to poll the ->work.need_resched flag instead of waiting for the
 479  * cross-CPU IPI to arrive. Use this option with caution.
 480  */
 481 static void poll_idle(void)
 482 {
 483         trace_power_start(POWER_CSTATE, 0, smp_processor_id());
 484         local_irq_enable();
 485         while (!need_resched())
 486                 cpu_relax();
 487         trace_power_end(0);
 488 }
 489
 490 /*
 491  * mwait selection logic:
 492  *
 493  * It depends on the CPU. For AMD CPUs that support MWAIT this is
 494  * wrong. Family 0x10 and 0x11 CPUs will enter C1 on HLT. Powersavings
 495  * then depend on a clock divisor and current Pstate of the core. If
 496  * all cores of a processor are in halt state (C1) the processor can
 497  * enter the C1E (C1 enhanced) state. If mwait is used this will never
 498  * happen.
 499  *
 500  * idle=mwait overrides this decision and forces the usage of mwait.
 501  */
 502 static int __cpuinitdata force_mwait;
 503
 504 #define MWAIT_INFO                      0x05
 505 #define MWAIT_ECX_EXTENDED_INFO         0x01
 506 #define MWAIT_EDX_C1                    0xf0
 507
 508 static int __cpuinit mwait_usable(const struct cpuinfo_x86 *c)
 509 {
 510         u32 eax, ebx, ecx, edx;
 511
 512         if (force_mwait)
 513                 return 1;
 514
 515         if (c->cpuid_level < MWAIT_INFO)
 516                 return 0;
 517
 518         cpuid(MWAIT_INFO, &eax, &ebx, &ecx, &edx);
 519         /* Check, whether EDX has extended info about MWAIT */
 520         if (!(ecx & MWAIT_ECX_EXTENDED_INFO))
 521                 return 1;
 522
 523         /*
 524          * edx enumeratios MONITOR/MWAIT extensions. Check, whether
 525          * C1  supports MWAIT
 526          */
 527         return (edx & MWAIT_EDX_C1);
 528 }
 529
 530 bool c1e_detected;
 531 EXPORT_SYMBOL(c1e_detected);
 532
 533 static cpumask_var_t c1e_mask;
 534
 535 void c1e_remove_cpu(int cpu)
 536 {
 537         if (c1e_mask != NULL)
 538                 cpumask_clear_cpu(cpu, c1e_mask);
 539 }
 540
 541 /*
 542  * C1E aware idle routine. We check for C1E active in the interrupt
 543  * pending message MSR. If we detect C1E, then we handle it the same
 544  * way as C3 power states (local apic timer and TSC stop)
 545  */
 546 static void c1e_idle(void)
 547 {
 548         if (need_resched())
 549                 return;
 550
 551         if (!c1e_detected) {
 552                 u32 lo, hi;
 553
 554                 rdmsr(MSR_K8_INT_PENDING_MSG, lo, hi);
 555
 556                 if (lo & K8_INTP_C1E_ACTIVE_MASK) {
 557                         c1e_detected = true;
 558                         if (!boot_cpu_has(X86_FEATURE_NONSTOP_TSC))
 559                                 mark_tsc_unstable("TSC halt in AMD C1E");
 560                         printk(KERN_INFO "System has AMD C1E enabled\n");
 561                 }
 562         }
 563
 564         if (c1e_detected) {
 565                 int cpu = smp_processor_id();
 566
 567                 if (!cpumask_test_cpu(cpu, c1e_mask)) {
 568                         cpumask_set_cpu(cpu, c1e_mask);
 569                         /*
 570                          * Force broadcast so ACPI can not interfere.
 571                          */
 572                         clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_FORCE,
 573                                            &cpu);
 574                         printk(KERN_INFO "Switch to broadcast mode on CPU%d\n",
 575                                cpu);
 576                 }
 577                 clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &cpu);
 578
 579                 default_idle();
 580
 581                 /*
 582                  * The switch back from broadcast mode needs to be
 583                  * called with interrupts disabled.
 584                  */
 585                  local_irq_disable();
 586                  clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT, &cpu);
 587                  local_irq_enable();
 588         } else
 589                 default_idle();
 590 }
 591
 592 void __cpuinit select_idle_routine(const struct cpuinfo_x86 *c)
 593 {
 594 #ifdef CONFIG_SMP
 595         if (pm_idle == poll_idle && smp_num_siblings > 1) {
 596                 printk_once(KERN_WARNING "WARNING: polling idle and HT enabled,"
 597                         " performance may degrade.\n");
 598         }
 599 #endif
 600         if (pm_idle)
 601                 return;
 602
 603         if (cpu_has(c, X86_FEATURE_MWAIT) && mwait_usable(c)) {
 604                 /*
 605                  * One CPU supports mwait => All CPUs supports mwait
 606                  */
 607                 printk(KERN_INFO "using mwait in idle threads.\n");
 608                 pm_idle = mwait_idle;
 609         } else if (cpu_has_amd_erratum(amd_erratum_400)) {
 610                 /* E400: APIC timer interrupt does not wake up CPU from C1e */
 611                 printk(KERN_INFO "using C1E aware idle routine\n");
 612                 pm_idle = c1e_idle;
 613         } else
 614                 pm_idle = default_idle;
 615 }
 616
 617 void __init init_c1e_mask(void)
 618 {
 619         /* If we're using c1e_idle, we need to allocate c1e_mask. */
 620         if (pm_idle == c1e_idle)
 621                 zalloc_cpumask_var(&c1e_mask, GFP_KERNEL);
 622 }
 623
 624 static int __init idle_setup(char *str)
 625 {
 626         if (!str)
 627                 return -EINVAL;
 628
 629         if (!strcmp(str, "poll")) {
 630                 printk("using polling idle threads.\n");
 631                 pm_idle = poll_idle;
 632         } else if (!strcmp(str, "mwait"))
 633                 force_mwait = 1;
 634         else if (!strcmp(str, "halt")) {
 635                 /*
 636                  * When the boot option of idle=halt is added, halt is
 637                  * forced to be used for CPU idle. In such case CPU C2/C3
 638                  * won't be used again.
 639                  * To continue to load the CPU idle driver, don't touch
 640                  * the boot_option_idle_override.
 641                  */
 642                 pm_idle = default_idle;
 643                 idle_halt = 1;
 644                 return 0;
 645         } else if (!strcmp(str, "nomwait")) {
 646                 /*
 647                  * If the boot option of "idle=nomwait" is added,
 648                  * it means that mwait will be disabled for CPU C2/C3
 649                  * states. In such case it won't touch the variable
 650                  * of boot_option_idle_override.
 651                  */
 652                 idle_nomwait = 1;
 653                 return 0;
 654         } else
 655                 return -1;
 656
 657         boot_option_idle_override = 1;
 658         return 0;
 659 }
 660 early_param("idle", idle_setup);
 661
 662 unsigned long arch_align_stack(unsigned long sp)
 663 {
 664         if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
 665                 sp -= get_random_int() % 8192;
 666         return sp & ~0xf;
 667 }
 668
 669 unsigned long arch_randomize_brk(struct mm_struct *mm)
 670 {
 671         unsigned long range_end = mm->brk + 0x02000000;
 672         return randomize_range(mm->brk, range_end, 0) ? : mm->brk;
 673 }
 674