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 <trace/events/power.h>
  13 #include <asm/system.h>
  14 #include <asm/apic.h>
  15 #include <asm/syscalls.h>
  16 #include <asm/idle.h>
  17 #include <asm/uaccess.h>
  18 #include <asm/i387.h>
  19 #include <asm/ds.h>
  20
  21 unsigned long idle_halt;
  22 EXPORT_SYMBOL(idle_halt);
  23 unsigned long idle_nomwait;
  24 EXPORT_SYMBOL(idle_nomwait);
  25
  26 struct kmem_cache *task_xstate_cachep;
  27
  28 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
  29 {
  30         *dst = *src;
  31         if (src->thread.xstate) {
  32                 dst->thread.xstate = kmem_cache_alloc(task_xstate_cachep,
  33                                                       GFP_KERNEL);
  34                 if (!dst->thread.xstate)
  35                         return -ENOMEM;
  36                 WARN_ON((unsigned long)dst->thread.xstate & 15);
  37                 memcpy(dst->thread.xstate, src->thread.xstate, xstate_size);
  38         }
  39         return 0;
  40 }
  41
  42 void free_thread_xstate(struct task_struct *tsk)
  43 {
  44         if (tsk->thread.xstate) {
  45                 kmem_cache_free(task_xstate_cachep, tsk->thread.xstate);
  46                 tsk->thread.xstate = NULL;
  47         }
  48
  49         WARN(tsk->thread.ds_ctx, "leaking DS context\n");
  50 }
  51
  52 void free_thread_info(struct thread_info *ti)
  53 {
  54         free_thread_xstate(ti->task);
  55         free_pages((unsigned long)ti, get_order(THREAD_SIZE));
  56 }
  57
  58 void arch_task_cache_init(void)
  59 {
  60         task_xstate_cachep =
  61                 kmem_cache_create("task_xstate", xstate_size,
  62                                   __alignof__(union thread_xstate),
  63                                   SLAB_PANIC | SLAB_NOTRACK, NULL);
  64 }
  65
  66 /*
  67  * Free current thread data structures etc..
  68  */
  69 void exit_thread(void)
  70 {
  71         struct task_struct *me = current;
  72         struct thread_struct *t = &me->thread;
  73         unsigned long *bp = t->io_bitmap_ptr;
  74
  75         if (bp) {
  76                 struct tss_struct *tss = &per_cpu(init_tss, get_cpu());
  77
  78                 t->io_bitmap_ptr = NULL;
  79                 clear_thread_flag(TIF_IO_BITMAP);
  80                 /*
  81                  * Careful, clear this in the TSS too:
  82                  */
  83                 memset(tss->io_bitmap, 0xff, t->io_bitmap_max);
  84                 t->io_bitmap_max = 0;
  85                 put_cpu();
  86                 kfree(bp);
  87         }
  88 }
  89
  90 void flush_thread(void)
  91 {
  92         struct task_struct *tsk = current;
  93
  94 #ifdef CONFIG_X86_64
  95         if (test_tsk_thread_flag(tsk, TIF_ABI_PENDING)) {
  96                 clear_tsk_thread_flag(tsk, TIF_ABI_PENDING);
  97                 if (test_tsk_thread_flag(tsk, TIF_IA32)) {
  98                         clear_tsk_thread_flag(tsk, TIF_IA32);
  99                 } else {
 100                         set_tsk_thread_flag(tsk, TIF_IA32);
 101                         current_thread_info()->status |= TS_COMPAT;
 102                 }
 103         }
 104 #endif
 105
 106         clear_tsk_thread_flag(tsk, TIF_DEBUG);
 107
 108         tsk->thread.debugreg0 = 0;
 109         tsk->thread.debugreg1 = 0;
 110         tsk->thread.debugreg2 = 0;
 111         tsk->thread.debugreg3 = 0;
 112         tsk->thread.debugreg6 = 0;
 113         tsk->thread.debugreg7 = 0;
 114         memset(tsk->thread.tls_array, 0, sizeof(tsk->thread.tls_array));
 115         /*
 116          * Forget coprocessor state..
 117          */
 118         tsk->fpu_counter = 0;
 119         clear_fpu(tsk);
 120         clear_used_math();
 121 }
 122
 123 static void hard_disable_TSC(void)
 124 {
 125         write_cr4(read_cr4() | X86_CR4_TSD);
 126 }
 127
 128 void disable_TSC(void)
 129 {
 130         preempt_disable();
 131         if (!test_and_set_thread_flag(TIF_NOTSC))
 132                 /*
 133                  * Must flip the CPU state synchronously with
 134                  * TIF_NOTSC in the current running context.
 135                  */
 136                 hard_disable_TSC();
 137         preempt_enable();
 138 }
 139
 140 static void hard_enable_TSC(void)
 141 {
 142         write_cr4(read_cr4() & ~X86_CR4_TSD);
 143 }
 144
 145 static void enable_TSC(void)
 146 {
 147         preempt_disable();
 148         if (test_and_clear_thread_flag(TIF_NOTSC))
 149                 /*
 150                  * Must flip the CPU state synchronously with
 151                  * TIF_NOTSC in the current running context.
 152                  */
 153                 hard_enable_TSC();
 154         preempt_enable();
 155 }
 156
 157 int get_tsc_mode(unsigned long adr)
 158 {
 159         unsigned int val;
 160
 161         if (test_thread_flag(TIF_NOTSC))
 162                 val = PR_TSC_SIGSEGV;
 163         else
 164                 val = PR_TSC_ENABLE;
 165
 166         return put_user(val, (unsigned int __user *)adr);
 167 }
 168
 169 int set_tsc_mode(unsigned int val)
 170 {
 171         if (val == PR_TSC_SIGSEGV)
 172                 disable_TSC();
 173         else if (val == PR_TSC_ENABLE)
 174                 enable_TSC();
 175         else
 176                 return -EINVAL;
 177
 178         return 0;
 179 }
 180
 181 void __switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p,
 182                       struct tss_struct *tss)
 183 {
 184         struct thread_struct *prev, *next;
 185
 186         prev = &prev_p->thread;
 187         next = &next_p->thread;
 188
 189         if (test_tsk_thread_flag(next_p, TIF_DS_AREA_MSR) ||
 190             test_tsk_thread_flag(prev_p, TIF_DS_AREA_MSR))
 191                 ds_switch_to(prev_p, next_p);
 192         else if (next->debugctlmsr != prev->debugctlmsr)
 193                 update_debugctlmsr(next->debugctlmsr);
 194
 195         if (test_tsk_thread_flag(next_p, TIF_DEBUG)) {
 196                 set_debugreg(next->debugreg0, 0);
 197                 set_debugreg(next->debugreg1, 1);
 198                 set_debugreg(next->debugreg2, 2);
 199                 set_debugreg(next->debugreg3, 3);
 200                 /* no 4 and 5 */
 201                 set_debugreg(next->debugreg6, 6);
 202                 set_debugreg(next->debugreg7, 7);
 203         }
 204
 205         if (test_tsk_thread_flag(prev_p, TIF_NOTSC) ^
 206             test_tsk_thread_flag(next_p, TIF_NOTSC)) {
 207                 /* prev and next are different */
 208                 if (test_tsk_thread_flag(next_p, TIF_NOTSC))
 209                         hard_disable_TSC();
 210                 else
 211                         hard_enable_TSC();
 212         }
 213
 214         if (test_tsk_thread_flag(next_p, TIF_IO_BITMAP)) {
 215                 /*
 216                  * Copy the relevant range of the IO bitmap.
 217                  * Normally this is 128 bytes or less:
 218                  */
 219                 memcpy(tss->io_bitmap, next->io_bitmap_ptr,
 220                        max(prev->io_bitmap_max, next->io_bitmap_max));
 221         } else if (test_tsk_thread_flag(prev_p, TIF_IO_BITMAP)) {
 222                 /*
 223                  * Clear any possible leftover bits:
 224                  */
 225                 memset(tss->io_bitmap, 0xff, prev->io_bitmap_max);
 226         }
 227 }
 228
 229 int sys_fork(struct pt_regs *regs)
 230 {
 231         return do_fork(SIGCHLD, regs->sp, regs, 0, NULL, NULL);
 232 }
 233
 234 /*
 235  * This is trivial, and on the face of it looks like it
 236  * could equally well be done in user mode.
 237  *
 238  * Not so, for quite unobvious reasons - register pressure.
 239  * In user mode vfork() cannot have a stack frame, and if
 240  * done by calling the "clone()" system call directly, you
 241  * do not have enough call-clobbered registers to hold all
 242  * the information you need.
 243  */
 244 int sys_vfork(struct pt_regs *regs)
 245 {
 246         return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, regs->sp, regs, 0,
 247                        NULL, NULL);
 248 }
 249
 250
 251 /*
 252  * Idle related variables and functions
 253  */
 254 unsigned long boot_option_idle_override = 0;
 255 EXPORT_SYMBOL(boot_option_idle_override);
 256
 257 /*
 258  * Powermanagement idle function, if any..
 259  */
 260 void (*pm_idle)(void);
 261 EXPORT_SYMBOL(pm_idle);
 262
 263 #ifdef CONFIG_X86_32
 264 /*
 265  * This halt magic was a workaround for ancient floppy DMA
 266  * wreckage. It should be safe to remove.
 267  */
 268 static int hlt_counter;
 269 void disable_hlt(void)
 270 {
 271         hlt_counter++;
 272 }
 273 EXPORT_SYMBOL(disable_hlt);
 274
 275 void enable_hlt(void)
 276 {
 277         hlt_counter--;
 278 }
 279 EXPORT_SYMBOL(enable_hlt);
 280
 281 static inline int hlt_use_halt(void)
 282 {
 283         return (!hlt_counter && boot_cpu_data.hlt_works_ok);
 284 }
 285 #else
 286 static inline int hlt_use_halt(void)
 287 {
 288         return 1;
 289 }
 290 #endif
 291
 292 /*
 293  * We use this if we don't have any better
 294  * idle routine..
 295  */
 296 void default_idle(void)
 297 {
 298         if (hlt_use_halt()) {
 299                 trace_power_start(POWER_CSTATE, 1);
 300                 current_thread_info()->status &= ~TS_POLLING;
 301                 /*
 302                  * TS_POLLING-cleared state must be visible before we
 303                  * test NEED_RESCHED:
 304                  */
 305                 smp_mb();
 306
 307                 if (!need_resched())
 308                         safe_halt();    /* enables interrupts racelessly */
 309                 else
 310                         local_irq_enable();
 311                 current_thread_info()->status |= TS_POLLING;
 312         } else {
 313                 local_irq_enable();
 314                 /* loop is done by the caller */
 315                 cpu_relax();
 316         }
 317 }
 318 #ifdef CONFIG_APM_MODULE
 319 EXPORT_SYMBOL(default_idle);
 320 #endif
 321
 322 void stop_this_cpu(void *dummy)
 323 {
 324         local_irq_disable();
 325         /*
 326          * Remove this CPU:
 327          */
 328         set_cpu_online(smp_processor_id(), false);
 329         disable_local_APIC();
 330
 331         for (;;) {
 332                 if (hlt_works(smp_processor_id()))
 333                         halt();
 334         }
 335 }
 336
 337 static void do_nothing(void *unused)
 338 {
 339 }
 340
 341 /*
 342  * cpu_idle_wait - Used to ensure that all the CPUs discard old value of
 343  * pm_idle and update to new pm_idle value. Required while changing pm_idle
 344  * handler on SMP systems.
 345  *
 346  * Caller must have changed pm_idle to the new value before the call. Old
 347  * pm_idle value will not be used by any CPU after the return of this function.
 348  */
 349 void cpu_idle_wait(void)
 350 {
 351         smp_mb();
 352         /* kick all the CPUs so that they exit out of pm_idle */
 353         smp_call_function(do_nothing, NULL, 1);
 354 }
 355 EXPORT_SYMBOL_GPL(cpu_idle_wait);
 356
 357 /*
 358  * This uses new MONITOR/MWAIT instructions on P4 processors with PNI,
 359  * which can obviate IPI to trigger checking of need_resched.
 360  * We execute MONITOR against need_resched and enter optimized wait state
 361  * through MWAIT. Whenever someone changes need_resched, we would be woken
 362  * up from MWAIT (without an IPI).
 363  *
 364  * New with Core Duo processors, MWAIT can take some hints based on CPU
 365  * capability.
 366  */
 367 void mwait_idle_with_hints(unsigned long ax, unsigned long cx)
 368 {
 369         trace_power_start(POWER_CSTATE, (ax>>4)+1);
 370         if (!need_resched()) {
 371                 if (cpu_has(&current_cpu_data, X86_FEATURE_CLFLUSH_MONITOR))
 372                         clflush((void *)&current_thread_info()->flags);
 373
 374                 __monitor((void *)&current_thread_info()->flags, 0, 0);
 375                 smp_mb();
 376                 if (!need_resched())
 377                         __mwait(ax, cx);
 378         }
 379 }
 380
 381 /* Default MONITOR/MWAIT with no hints, used for default C1 state */
 382 static void mwait_idle(void)
 383 {
 384         if (!need_resched()) {
 385                 trace_power_start(POWER_CSTATE, 1);
 386                 if (cpu_has(&current_cpu_data, X86_FEATURE_CLFLUSH_MONITOR))
 387                         clflush((void *)&current_thread_info()->flags);
 388
 389                 __monitor((void *)&current_thread_info()->flags, 0, 0);
 390                 smp_mb();
 391                 if (!need_resched())
 392                         __sti_mwait(0, 0);
 393                 else
 394                         local_irq_enable();
 395         } else
 396                 local_irq_enable();
 397 }
 398
 399 /*
 400  * On SMP it's slightly faster (but much more power-consuming!)
 401  * to poll the ->work.need_resched flag instead of waiting for the
 402  * cross-CPU IPI to arrive. Use this option with caution.
 403  */
 404 static void poll_idle(void)
 405 {
 406         trace_power_start(POWER_CSTATE, 0);
 407         local_irq_enable();
 408         while (!need_resched())
 409                 cpu_relax();
 410         trace_power_end(0);
 411 }
 412
 413 /*
 414  * mwait selection logic:
 415  *
 416  * It depends on the CPU. For AMD CPUs that support MWAIT this is
 417  * wrong. Family 0x10 and 0x11 CPUs will enter C1 on HLT. Powersavings
 418  * then depend on a clock divisor and current Pstate of the core. If
 419  * all cores of a processor are in halt state (C1) the processor can
 420  * enter the C1E (C1 enhanced) state. If mwait is used this will never
 421  * happen.
 422  *
 423  * idle=mwait overrides this decision and forces the usage of mwait.
 424  */
 425 static int __cpuinitdata force_mwait;
 426
 427 #define MWAIT_INFO                      0x05
 428 #define MWAIT_ECX_EXTENDED_INFO         0x01
 429 #define MWAIT_EDX_C1                    0xf0
 430
 431 static int __cpuinit mwait_usable(const struct cpuinfo_x86 *c)
 432 {
 433         u32 eax, ebx, ecx, edx;
 434
 435         if (force_mwait)
 436                 return 1;
 437
 438         if (c->cpuid_level < MWAIT_INFO)
 439                 return 0;
 440
 441         cpuid(MWAIT_INFO, &eax, &ebx, &ecx, &edx);
 442         /* Check, whether EDX has extended info about MWAIT */
 443         if (!(ecx & MWAIT_ECX_EXTENDED_INFO))
 444                 return 1;
 445
 446         /*
 447          * edx enumeratios MONITOR/MWAIT extensions. Check, whether
 448          * C1  supports MWAIT
 449          */
 450         return (edx & MWAIT_EDX_C1);
 451 }
 452
 453 /*
 454  * Check for AMD CPUs, which have potentially C1E support
 455  */
 456 static int __cpuinit check_c1e_idle(const struct cpuinfo_x86 *c)
 457 {
 458         if (c->x86_vendor != X86_VENDOR_AMD)
 459                 return 0;
 460
 461         if (c->x86 < 0x0F)
 462                 return 0;
 463
 464         /* Family 0x0f models < rev F do not have C1E */
 465         if (c->x86 == 0x0f && c->x86_model < 0x40)
 466                 return 0;
 467
 468         return 1;
 469 }
 470
 471 static cpumask_var_t c1e_mask;
 472 static int c1e_detected;
 473
 474 void c1e_remove_cpu(int cpu)
 475 {
 476         if (c1e_mask != NULL)
 477                 cpumask_clear_cpu(cpu, c1e_mask);
 478 }
 479
 480 /*
 481  * C1E aware idle routine. We check for C1E active in the interrupt
 482  * pending message MSR. If we detect C1E, then we handle it the same
 483  * way as C3 power states (local apic timer and TSC stop)
 484  */
 485 static void c1e_idle(void)
 486 {
 487         if (need_resched())
 488                 return;
 489
 490         if (!c1e_detected) {
 491                 u32 lo, hi;
 492
 493                 rdmsr(MSR_K8_INT_PENDING_MSG, lo, hi);
 494                 if (lo & K8_INTP_C1E_ACTIVE_MASK) {
 495                         c1e_detected = 1;
 496                         if (!boot_cpu_has(X86_FEATURE_NONSTOP_TSC))
 497                                 mark_tsc_unstable("TSC halt in AMD C1E");
 498                         printk(KERN_INFO "System has AMD C1E enabled\n");
 499                         set_cpu_cap(&boot_cpu_data, X86_FEATURE_AMDC1E);
 500                 }
 501         }
 502
 503         if (c1e_detected) {
 504                 int cpu = smp_processor_id();
 505
 506                 if (!cpumask_test_cpu(cpu, c1e_mask)) {
 507                         cpumask_set_cpu(cpu, c1e_mask);
 508                         /*
 509                          * Force broadcast so ACPI can not interfere.
 510                          */
 511                         clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_FORCE,
 512                                            &cpu);
 513                         printk(KERN_INFO "Switch to broadcast mode on CPU%d\n",
 514                                cpu);
 515                 }
 516                 clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &cpu);
 517
 518                 default_idle();
 519
 520                 /*
 521                  * The switch back from broadcast mode needs to be
 522                  * called with interrupts disabled.
 523                  */
 524                  local_irq_disable();
 525                  clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT, &cpu);
 526                  local_irq_enable();
 527         } else
 528                 default_idle();
 529 }
 530
 531 void __cpuinit select_idle_routine(const struct cpuinfo_x86 *c)
 532 {
 533 #ifdef CONFIG_SMP
 534         if (pm_idle == poll_idle && smp_num_siblings > 1) {
 535                 printk(KERN_WARNING "WARNING: polling idle and HT enabled,"
 536                         " performance may degrade.\n");
 537         }
 538 #endif
 539         if (pm_idle)
 540                 return;
 541
 542         if (cpu_has(c, X86_FEATURE_MWAIT) && mwait_usable(c)) {
 543                 /*
 544                  * One CPU supports mwait => All CPUs supports mwait
 545                  */
 546                 printk(KERN_INFO "using mwait in idle threads.\n");
 547                 pm_idle = mwait_idle;
 548         } else if (check_c1e_idle(c)) {
 549                 printk(KERN_INFO "using C1E aware idle routine\n");
 550                 pm_idle = c1e_idle;
 551         } else
 552                 pm_idle = default_idle;
 553 }
 554
 555 void __init init_c1e_mask(void)
 556 {
 557         /* If we're using c1e_idle, we need to allocate c1e_mask. */
 558         if (pm_idle == c1e_idle)
 559                 zalloc_cpumask_var(&c1e_mask, GFP_KERNEL);
 560 }
 561
 562 static int __init idle_setup(char *str)
 563 {
 564         if (!str)
 565                 return -EINVAL;
 566
 567         if (!strcmp(str, "poll")) {
 568                 printk("using polling idle threads.\n");
 569                 pm_idle = poll_idle;
 570         } else if (!strcmp(str, "mwait"))
 571                 force_mwait = 1;
 572         else if (!strcmp(str, "halt")) {
 573                 /*
 574                  * When the boot option of idle=halt is added, halt is
 575                  * forced to be used for CPU idle. In such case CPU C2/C3
 576                  * won't be used again.
 577                  * To continue to load the CPU idle driver, don't touch
 578                  * the boot_option_idle_override.
 579                  */
 580                 pm_idle = default_idle;
 581                 idle_halt = 1;
 582                 return 0;
 583         } else if (!strcmp(str, "nomwait")) {
 584                 /*
 585                  * If the boot option of "idle=nomwait" is added,
 586                  * it means that mwait will be disabled for CPU C2/C3
 587                  * states. In such case it won't touch the variable
 588                  * of boot_option_idle_override.
 589                  */
 590                 idle_nomwait = 1;
 591                 return 0;
 592         } else
 593                 return -1;
 594
 595         boot_option_idle_override = 1;
 596         return 0;
 597 }
 598 early_param("idle", idle_setup);
 599
 600 unsigned long arch_align_stack(unsigned long sp)
 601 {
 602         if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
 603                 sp -= get_random_int() % 8192;
 604         return sp & ~0xf;
 605 }
 606
 607 unsigned long arch_randomize_brk(struct mm_struct *mm)
 608 {
 609         unsigned long range_end = mm->brk + 0x02000000;
 610         return randomize_range(mm->brk, range_end, 0) ? : mm->brk;
 611 }
 612