arch/x86/kernel/process.c

   1 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
   2
   3 #include <linux/errno.h>
   4 #include <linux/kernel.h>
   5 #include <linux/mm.h>
   6 #include <linux/smp.h>
   7 #include <linux/prctl.h>
   8 #include <linux/slab.h>
   9 #include <linux/sched.h>
  10 #include <linux/module.h>
  11 #include <linux/pm.h>
  12 #include <linux/clockchips.h>
  13 #include <linux/random.h>
  14 #include <linux/user-return-notifier.h>
  15 #include <linux/dmi.h>
  16 #include <linux/utsname.h>
  17 #include <linux/stackprotector.h>
  18 #include <linux/tick.h>
  19 #include <linux/cpuidle.h>
  20 #include <trace/events/power.h>
  21 #include <linux/hw_breakpoint.h>
  22 #include <asm/cpu.h>
  23 #include <asm/apic.h>
  24 #include <asm/syscalls.h>
  25 #include <asm/idle.h>
  26 #include <asm/uaccess.h>
  27 #include <asm/i387.h>
  28 #include <asm/fpu-internal.h>
  29 #include <asm/debugreg.h>
  30 #include <asm/nmi.h>
  31
  32 /*
  33  * per-CPU TSS segments. Threads are completely 'soft' on Linux,
  34  * no more per-task TSS's. The TSS size is kept cacheline-aligned
  35  * so they are allowed to end up in the .data..cacheline_aligned
  36  * section. Since TSS's are completely CPU-local, we want them
  37  * on exact cacheline boundaries, to eliminate cacheline ping-pong.
  38  */
  39 __visible DEFINE_PER_CPU_SHARED_ALIGNED(struct tss_struct, init_tss) = INIT_TSS;
  40
  41 #ifdef CONFIG_X86_64
  42 static DEFINE_PER_CPU(unsigned char, is_idle);
  43 static ATOMIC_NOTIFIER_HEAD(idle_notifier);
  44
  45 void idle_notifier_register(struct notifier_block *n)
  46 {
  47         atomic_notifier_chain_register(&idle_notifier, n);
  48 }
  49 EXPORT_SYMBOL_GPL(idle_notifier_register);
  50
  51 void idle_notifier_unregister(struct notifier_block *n)
  52 {
  53         atomic_notifier_chain_unregister(&idle_notifier, n);
  54 }
  55 EXPORT_SYMBOL_GPL(idle_notifier_unregister);
  56 #endif
  57
  58 struct kmem_cache *task_xstate_cachep;
  59 EXPORT_SYMBOL_GPL(task_xstate_cachep);
  60
  61 /*
  62  * this gets called so that we can store lazy state into memory and copy the
  63  * current task into the new thread.
  64  */
  65 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
  66 {
  67         int ret;
  68
  69         *dst = *src;
  70         if (fpu_allocated(&src->thread.fpu)) {
  71                 memset(&dst->thread.fpu, 0, sizeof(dst->thread.fpu));
  72                 ret = fpu_alloc(&dst->thread.fpu);
  73                 if (ret)
  74                         return ret;
  75                 fpu_copy(dst, src);
  76         }
  77         return 0;
  78 }
  79
  80 void free_thread_xstate(struct task_struct *tsk)
  81 {
  82         fpu_free(&tsk->thread.fpu);
  83 }
  84
  85 void arch_release_task_struct(struct task_struct *tsk)
  86 {
  87         free_thread_xstate(tsk);
  88 }
  89
  90 void arch_task_cache_init(void)
  91 {
  92         task_xstate_cachep =
  93                 kmem_cache_create("task_xstate", xstate_size,
  94                                   __alignof__(union thread_xstate),
  95                                   SLAB_PANIC | SLAB_NOTRACK, NULL);
  96 }
  97
  98 /*
  99  * Free current thread data structures etc..
 100  */
 101 void exit_thread(void)
 102 {
 103         struct task_struct *me = current;
 104         struct thread_struct *t = &me->thread;
 105         unsigned long *bp = t->io_bitmap_ptr;
 106
 107         if (bp) {
 108                 struct tss_struct *tss = &per_cpu(init_tss, get_cpu());
 109
 110                 t->io_bitmap_ptr = NULL;
 111                 clear_thread_flag(TIF_IO_BITMAP);
 112                 /*
 113                  * Careful, clear this in the TSS too:
 114                  */
 115                 memset(tss->io_bitmap, 0xff, t->io_bitmap_max);
 116                 t->io_bitmap_max = 0;
 117                 put_cpu();
 118                 kfree(bp);
 119         }
 120
 121         drop_fpu(me);
 122 }
 123
 124 void flush_thread(void)
 125 {
 126         struct task_struct *tsk = current;
 127
 128         flush_ptrace_hw_breakpoint(tsk);
 129         memset(tsk->thread.tls_array, 0, sizeof(tsk->thread.tls_array));
 130         drop_init_fpu(tsk);
 131         /*
 132          * Free the FPU state for non xsave platforms. They get reallocated
 133          * lazily at the first use.
 134          */
 135         if (!use_eager_fpu())
 136                 free_thread_xstate(tsk);
 137 }
 138
 139 static void hard_disable_TSC(void)
 140 {
 141         write_cr4(read_cr4() | X86_CR4_TSD);
 142 }
 143
 144 void disable_TSC(void)
 145 {
 146         preempt_disable();
 147         if (!test_and_set_thread_flag(TIF_NOTSC))
 148                 /*
 149                  * Must flip the CPU state synchronously with
 150                  * TIF_NOTSC in the current running context.
 151                  */
 152                 hard_disable_TSC();
 153         preempt_enable();
 154 }
 155
 156 static void hard_enable_TSC(void)
 157 {
 158         write_cr4(read_cr4() & ~X86_CR4_TSD);
 159 }
 160
 161 static void enable_TSC(void)
 162 {
 163         preempt_disable();
 164         if (test_and_clear_thread_flag(TIF_NOTSC))
 165                 /*
 166                  * Must flip the CPU state synchronously with
 167                  * TIF_NOTSC in the current running context.
 168                  */
 169                 hard_enable_TSC();
 170         preempt_enable();
 171 }
 172
 173 int get_tsc_mode(unsigned long adr)
 174 {
 175         unsigned int val;
 176
 177         if (test_thread_flag(TIF_NOTSC))
 178                 val = PR_TSC_SIGSEGV;
 179         else
 180                 val = PR_TSC_ENABLE;
 181
 182         return put_user(val, (unsigned int __user *)adr);
 183 }
 184
 185 int set_tsc_mode(unsigned int val)
 186 {
 187         if (val == PR_TSC_SIGSEGV)
 188                 disable_TSC();
 189         else if (val == PR_TSC_ENABLE)
 190                 enable_TSC();
 191         else
 192                 return -EINVAL;
 193
 194         return 0;
 195 }
 196
 197 void __switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p,
 198                       struct tss_struct *tss)
 199 {
 200         struct thread_struct *prev, *next;
 201
 202         prev = &prev_p->thread;
 203         next = &next_p->thread;
 204
 205         if (test_tsk_thread_flag(prev_p, TIF_BLOCKSTEP) ^
 206             test_tsk_thread_flag(next_p, TIF_BLOCKSTEP)) {
 207                 unsigned long debugctl = get_debugctlmsr();
 208
 209                 debugctl &= ~DEBUGCTLMSR_BTF;
 210                 if (test_tsk_thread_flag(next_p, TIF_BLOCKSTEP))
 211                         debugctl |= DEBUGCTLMSR_BTF;
 212
 213                 update_debugctlmsr(debugctl);
 214         }
 215
 216         if (test_tsk_thread_flag(prev_p, TIF_NOTSC) ^
 217             test_tsk_thread_flag(next_p, TIF_NOTSC)) {
 218                 /* prev and next are different */
 219                 if (test_tsk_thread_flag(next_p, TIF_NOTSC))
 220                         hard_disable_TSC();
 221                 else
 222                         hard_enable_TSC();
 223         }
 224
 225         if (test_tsk_thread_flag(next_p, TIF_IO_BITMAP)) {
 226                 /*
 227                  * Copy the relevant range of the IO bitmap.
 228                  * Normally this is 128 bytes or less:
 229                  */
 230                 memcpy(tss->io_bitmap, next->io_bitmap_ptr,
 231                        max(prev->io_bitmap_max, next->io_bitmap_max));
 232         } else if (test_tsk_thread_flag(prev_p, TIF_IO_BITMAP)) {
 233                 /*
 234                  * Clear any possible leftover bits:
 235                  */
 236                 memset(tss->io_bitmap, 0xff, prev->io_bitmap_max);
 237         }
 238         propagate_user_return_notify(prev_p, next_p);
 239 }
 240
 241 /*
 242  * Idle related variables and functions
 243  */
 244 unsigned long boot_option_idle_override = IDLE_NO_OVERRIDE;
 245 EXPORT_SYMBOL(boot_option_idle_override);
 246
 247 static void (*x86_idle)(void);
 248
 249 #ifndef CONFIG_SMP
 250 static inline void play_dead(void)
 251 {
 252         BUG();
 253 }
 254 #endif
 255
 256 #ifdef CONFIG_X86_64
 257 void enter_idle(void)
 258 {
 259         this_cpu_write(is_idle, 1);
 260         atomic_notifier_call_chain(&idle_notifier, IDLE_START, NULL);
 261 }
 262
 263 static void __exit_idle(void)
 264 {
 265         if (x86_test_and_clear_bit_percpu(0, is_idle) == 0)
 266                 return;
 267         atomic_notifier_call_chain(&idle_notifier, IDLE_END, NULL);
 268 }
 269
 270 /* Called from interrupts to signify idle end */
 271 void exit_idle(void)
 272 {
 273         /* idle loop has pid 0 */
 274         if (current->pid)
 275                 return;
 276         __exit_idle();
 277 }
 278 #endif
 279
 280 void arch_cpu_idle_enter(void)
 281 {
 282         local_touch_nmi();
 283         enter_idle();
 284 }
 285
 286 void arch_cpu_idle_exit(void)
 287 {
 288         __exit_idle();
 289 }
 290
 291 void arch_cpu_idle_dead(void)
 292 {
 293         play_dead();
 294 }
 295
 296 /*
 297  * Called from the generic idle code.
 298  */
 299 void arch_cpu_idle(void)
 300 {
 301         if (cpuidle_idle_call())
 302                 x86_idle();
 303         else
 304                 local_irq_enable();
 305 }
 306
 307 /*
 308  * We use this if we don't have any better idle routine..
 309  */
 310 void default_idle(void)
 311 {
 312         trace_cpu_idle_rcuidle(1, smp_processor_id());
 313         safe_halt();
 314         trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, smp_processor_id());
 315 }
 316 #ifdef CONFIG_APM_MODULE
 317 EXPORT_SYMBOL(default_idle);
 318 #endif
 319
 320 #ifdef CONFIG_XEN
 321 bool xen_set_default_idle(void)
 322 {
 323         bool ret = !!x86_idle;
 324
 325         x86_idle = default_idle;
 326
 327         return ret;
 328 }
 329 #endif
 330 void stop_this_cpu(void *dummy)
 331 {
 332         local_irq_disable();
 333         /*
 334          * Remove this CPU:
 335          */
 336         set_cpu_online(smp_processor_id(), false);
 337         disable_local_APIC();
 338
 339         for (;;)
 340                 halt();
 341 }
 342
 343 bool amd_e400_c1e_detected;
 344 EXPORT_SYMBOL(amd_e400_c1e_detected);
 345
 346 static cpumask_var_t amd_e400_c1e_mask;
 347
 348 void amd_e400_remove_cpu(int cpu)
 349 {
 350         if (amd_e400_c1e_mask != NULL)
 351                 cpumask_clear_cpu(cpu, amd_e400_c1e_mask);
 352 }
 353
 354 /*
 355  * AMD Erratum 400 aware idle routine. We check for C1E active in the interrupt
 356  * pending message MSR. If we detect C1E, then we handle it the same
 357  * way as C3 power states (local apic timer and TSC stop)
 358  */
 359 static void amd_e400_idle(void)
 360 {
 361         if (!amd_e400_c1e_detected) {
 362                 u32 lo, hi;
 363
 364                 rdmsr(MSR_K8_INT_PENDING_MSG, lo, hi);
 365
 366                 if (lo & K8_INTP_C1E_ACTIVE_MASK) {
 367                         amd_e400_c1e_detected = true;
 368                         if (!boot_cpu_has(X86_FEATURE_NONSTOP_TSC))
 369                                 mark_tsc_unstable("TSC halt in AMD C1E");
 370                         pr_info("System has AMD C1E enabled\n");
 371                 }
 372         }
 373
 374         if (amd_e400_c1e_detected) {
 375                 int cpu = smp_processor_id();
 376
 377                 if (!cpumask_test_cpu(cpu, amd_e400_c1e_mask)) {
 378                         cpumask_set_cpu(cpu, amd_e400_c1e_mask);
 379                         /*
 380                          * Force broadcast so ACPI can not interfere.
 381                          */
 382                         clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_FORCE,
 383                                            &cpu);
 384                         pr_info("Switch to broadcast mode on CPU%d\n", cpu);
 385                 }
 386                 clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &cpu);
 387
 388                 default_idle();
 389
 390                 /*
 391                  * The switch back from broadcast mode needs to be
 392                  * called with interrupts disabled.
 393                  */
 394                  local_irq_disable();
 395                  clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT, &cpu);
 396                  local_irq_enable();
 397         } else
 398                 default_idle();
 399 }
 400
 401 void select_idle_routine(const struct cpuinfo_x86 *c)
 402 {
 403 #ifdef CONFIG_SMP
 404         if (boot_option_idle_override == IDLE_POLL && smp_num_siblings > 1)
 405                 pr_warn_once("WARNING: polling idle and HT enabled, performance may degrade\n");
 406 #endif
 407         if (x86_idle || boot_option_idle_override == IDLE_POLL)
 408                 return;
 409
 410         if (cpu_has_bug(c, X86_BUG_AMD_APIC_C1E)) {
 411                 /* E400: APIC timer interrupt does not wake up CPU from C1e */
 412                 pr_info("using AMD E400 aware idle routine\n");
 413                 x86_idle = amd_e400_idle;
 414         } else
 415                 x86_idle = default_idle;
 416 }
 417
 418 void __init init_amd_e400_c1e_mask(void)
 419 {
 420         /* If we're using amd_e400_idle, we need to allocate amd_e400_c1e_mask. */
 421         if (x86_idle == amd_e400_idle)
 422                 zalloc_cpumask_var(&amd_e400_c1e_mask, GFP_KERNEL);
 423 }
 424
 425 static int __init idle_setup(char *str)
 426 {
 427         if (!str)
 428                 return -EINVAL;
 429
 430         if (!strcmp(str, "poll")) {
 431                 pr_info("using polling idle threads\n");
 432                 boot_option_idle_override = IDLE_POLL;
 433                 cpu_idle_poll_ctrl(true);
 434         } else if (!strcmp(str, "halt")) {
 435                 /*
 436                  * When the boot option of idle=halt is added, halt is
 437                  * forced to be used for CPU idle. In such case CPU C2/C3
 438                  * won't be used again.
 439                  * To continue to load the CPU idle driver, don't touch
 440                  * the boot_option_idle_override.
 441                  */
 442                 x86_idle = default_idle;
 443                 boot_option_idle_override = IDLE_HALT;
 444         } else if (!strcmp(str, "nomwait")) {
 445                 /*
 446                  * If the boot option of "idle=nomwait" is added,
 447                  * it means that mwait will be disabled for CPU C2/C3
 448                  * states. In such case it won't touch the variable
 449                  * of boot_option_idle_override.
 450                  */
 451                 boot_option_idle_override = IDLE_NOMWAIT;
 452         } else
 453                 return -1;
 454
 455         return 0;
 456 }
 457 early_param("idle", idle_setup);
 458
 459 unsigned long arch_align_stack(unsigned long sp)
 460 {
 461         if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
 462                 sp -= get_random_int() % 8192;
 463         return sp & ~0xf;
 464 }
 465
 466 unsigned long arch_randomize_brk(struct mm_struct *mm)
 467 {
 468         unsigned long range_end = mm->brk + 0x02000000;
 469         return randomize_range(mm->brk, range_end, 0) ? : mm->brk;
 470 }
 471