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/stackprotector.h>
  20 #include <linux/cpu.h>
  21 #include <linux/errno.h>
  22 #include <linux/sched.h>
  23 #include <linux/fs.h>
  24 #include <linux/kernel.h>
  25 #include <linux/mm.h>
  26 #include <linux/elfcore.h>
  27 #include <linux/smp.h>
  28 #include <linux/slab.h>
  29 #include <linux/user.h>
  30 #include <linux/interrupt.h>
  31 #include <linux/utsname.h>
  32 #include <linux/delay.h>
  33 #include <linux/module.h>
  34 #include <linux/ptrace.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 #include <linux/prctl.h>
  41 #include <linux/uaccess.h>
  42 #include <linux/io.h>
  43 #include <linux/ftrace.h>
  44 #include <linux/dmi.h>
  45
  46 #include <asm/pgtable.h>
  47 #include <asm/system.h>
  48 #include <asm/processor.h>
  49 #include <asm/i387.h>
  50 #include <asm/mmu_context.h>
  51 #include <asm/prctl.h>
  52 #include <asm/desc.h>
  53 #include <asm/proto.h>
  54 #include <asm/ia32.h>
  55 #include <asm/idle.h>
  56 #include <asm/syscalls.h>
  57 #include <asm/ds.h>
  58
  59 asmlinkage extern void ret_from_fork(void);
  60
  61 DEFINE_PER_CPU(struct task_struct *, current_task) = &init_task;
  62 EXPORT_PER_CPU_SYMBOL(current_task);
  63
  64 DEFINE_PER_CPU(unsigned long, old_rsp);
  65 static DEFINE_PER_CPU(unsigned char, is_idle);
  66
  67 unsigned long kernel_thread_flags = CLONE_VM | CLONE_UNTRACED;
  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_GPL(idle_notifier_unregister);
  82
  83 void enter_idle(void)
  84 {
  85         percpu_write(is_idle, 1);
  86         atomic_notifier_call_chain(&idle_notifier, IDLE_START, NULL);
  87 }
  88
  89 static void __exit_idle(void)
  90 {
  91         if (x86_test_and_clear_bit_percpu(0, is_idle) == 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 #ifndef CONFIG_SMP
 106 static inline void play_dead(void)
 107 {
 108         BUG();
 109 }
 110 #endif
 111
 112 /*
 113  * The idle thread. There's no useful work to be
 114  * done, so just try to conserve power and have a
 115  * low exit latency (ie sit in a loop waiting for
 116  * somebody to say that they'd like to reschedule)
 117  */
 118 void cpu_idle(void)
 119 {
 120         current_thread_info()->status |= TS_POLLING;
 121
 122         /*
 123          * If we're the non-boot CPU, nothing set the stack canary up
 124          * for us.  CPU0 already has it initialized but no harm in
 125          * doing it again.  This is a good place for updating it, as
 126          * we wont ever return from this function (so the invalid
 127          * canaries already on the stack wont ever trigger).
 128          */
 129         boot_init_stack_canary();
 130
 131         /* endless idle loop with no priority at all */
 132         while (1) {
 133                 tick_nohz_stop_sched_tick(1);
 134                 while (!need_resched()) {
 135
 136                         rmb();
 137
 138                         if (cpu_is_offline(smp_processor_id()))
 139                                 play_dead();
 140                         /*
 141                          * Idle routines should keep interrupts disabled
 142                          * from here on, until they go to idle.
 143                          * Otherwise, idle callbacks can misfire.
 144                          */
 145                         local_irq_disable();
 146                         enter_idle();
 147                         /* Don't trace irqs off for idle */
 148                         stop_critical_timings();
 149                         pm_idle();
 150                         start_critical_timings();
 151                         /* In many cases the interrupt that ended idle
 152                            has already called exit_idle. But some idle
 153                            loops can be woken up without interrupt. */
 154                         __exit_idle();
 155                 }
 156
 157                 tick_nohz_restart_sched_tick();
 158                 preempt_enable_no_resched();
 159                 schedule();
 160                 preempt_disable();
 161         }
 162 }
 163
 164 /* Prints also some state that isn't saved in the pt_regs */
 165 void __show_regs(struct pt_regs *regs, int all)
 166 {
 167         unsigned long cr0 = 0L, cr2 = 0L, cr3 = 0L, cr4 = 0L, fs, gs, shadowgs;
 168         unsigned long d0, d1, d2, d3, d6, d7;
 169         unsigned int fsindex, gsindex;
 170         unsigned int ds, cs, es;
 171         const char *board;
 172
 173         printk("\n");
 174         print_modules();
 175         board = dmi_get_system_info(DMI_PRODUCT_NAME);
 176         if (!board)
 177                 board = "";
 178         printk(KERN_INFO "Pid: %d, comm: %.20s %s %s %.*s %s\n",
 179                 current->pid, current->comm, print_tainted(),
 180                 init_utsname()->release,
 181                 (int)strcspn(init_utsname()->version, " "),
 182                 init_utsname()->version, board);
 183         printk(KERN_INFO "RIP: %04lx:[<%016lx>] ", regs->cs & 0xffff, regs->ip);
 184         printk_address(regs->ip, 1);
 185         printk(KERN_INFO "RSP: %04lx:%016lx  EFLAGS: %08lx\n", regs->ss,
 186                         regs->sp, regs->flags);
 187         printk(KERN_INFO "RAX: %016lx RBX: %016lx RCX: %016lx\n",
 188                regs->ax, regs->bx, regs->cx);
 189         printk(KERN_INFO "RDX: %016lx RSI: %016lx RDI: %016lx\n",
 190                regs->dx, regs->si, regs->di);
 191         printk(KERN_INFO "RBP: %016lx R08: %016lx R09: %016lx\n",
 192                regs->bp, regs->r8, regs->r9);
 193         printk(KERN_INFO "R10: %016lx R11: %016lx R12: %016lx\n",
 194                regs->r10, regs->r11, regs->r12);
 195         printk(KERN_INFO "R13: %016lx R14: %016lx R15: %016lx\n",
 196                regs->r13, regs->r14, regs->r15);
 197
 198         asm("movl %%ds,%0" : "=r" (ds));
 199         asm("movl %%cs,%0" : "=r" (cs));
 200         asm("movl %%es,%0" : "=r" (es));
 201         asm("movl %%fs,%0" : "=r" (fsindex));
 202         asm("movl %%gs,%0" : "=r" (gsindex));
 203
 204         rdmsrl(MSR_FS_BASE, fs);
 205         rdmsrl(MSR_GS_BASE, gs);
 206         rdmsrl(MSR_KERNEL_GS_BASE, shadowgs);
 207
 208         if (!all)
 209                 return;
 210
 211         cr0 = read_cr0();
 212         cr2 = read_cr2();
 213         cr3 = read_cr3();
 214         cr4 = read_cr4();
 215
 216         printk(KERN_INFO "FS:  %016lx(%04x) GS:%016lx(%04x) knlGS:%016lx\n",
 217                fs, fsindex, gs, gsindex, shadowgs);
 218         printk(KERN_INFO "CS:  %04x DS: %04x ES: %04x CR0: %016lx\n", cs, ds,
 219                         es, cr0);
 220         printk(KERN_INFO "CR2: %016lx CR3: %016lx CR4: %016lx\n", cr2, cr3,
 221                         cr4);
 222
 223         get_debugreg(d0, 0);
 224         get_debugreg(d1, 1);
 225         get_debugreg(d2, 2);
 226         printk(KERN_INFO "DR0: %016lx DR1: %016lx DR2: %016lx\n", d0, d1, d2);
 227         get_debugreg(d3, 3);
 228         get_debugreg(d6, 6);
 229         get_debugreg(d7, 7);
 230         printk(KERN_INFO "DR3: %016lx DR6: %016lx DR7: %016lx\n", d3, d6, d7);
 231 }
 232
 233 void show_regs(struct pt_regs *regs)
 234 {
 235         printk(KERN_INFO "CPU %d:", smp_processor_id());
 236         __show_regs(regs, 1);
 237         show_trace(NULL, regs, (void *)(regs + 1), regs->bp);
 238 }
 239
 240 void release_thread(struct task_struct *dead_task)
 241 {
 242         if (dead_task->mm) {
 243                 if (dead_task->mm->context.size) {
 244                         printk("WARNING: dead process %8s still has LDT? <%p/%d>\n",
 245                                         dead_task->comm,
 246                                         dead_task->mm->context.ldt,
 247                                         dead_task->mm->context.size);
 248                         BUG();
 249                 }
 250         }
 251 }
 252
 253 static inline void set_32bit_tls(struct task_struct *t, int tls, u32 addr)
 254 {
 255         struct user_desc ud = {
 256                 .base_addr = addr,
 257                 .limit = 0xfffff,
 258                 .seg_32bit = 1,
 259                 .limit_in_pages = 1,
 260                 .useable = 1,
 261         };
 262         struct desc_struct *desc = t->thread.tls_array;
 263         desc += tls;
 264         fill_ldt(desc, &ud);
 265 }
 266
 267 static inline u32 read_32bit_tls(struct task_struct *t, int tls)
 268 {
 269         return get_desc_base(&t->thread.tls_array[tls]);
 270 }
 271
 272 /*
 273  * This gets called before we allocate a new thread and copy
 274  * the current task into it.
 275  */
 276 void prepare_to_copy(struct task_struct *tsk)
 277 {
 278         unlazy_fpu(tsk);
 279 }
 280
 281 int copy_thread(unsigned long clone_flags, unsigned long sp,
 282                 unsigned long unused,
 283         struct task_struct *p, struct pt_regs *regs)
 284 {
 285         int err;
 286         struct pt_regs *childregs;
 287         struct task_struct *me = current;
 288
 289         childregs = ((struct pt_regs *)
 290                         (THREAD_SIZE + task_stack_page(p))) - 1;
 291         *childregs = *regs;
 292
 293         childregs->ax = 0;
 294         childregs->sp = sp;
 295         if (sp == ~0UL)
 296                 childregs->sp = (unsigned long)childregs;
 297
 298         p->thread.sp = (unsigned long) childregs;
 299         p->thread.sp0 = (unsigned long) (childregs+1);
 300         p->thread.usersp = me->thread.usersp;
 301
 302         set_tsk_thread_flag(p, TIF_FORK);
 303
 304         p->thread.fs = me->thread.fs;
 305         p->thread.gs = me->thread.gs;
 306
 307         savesegment(gs, p->thread.gsindex);
 308         savesegment(fs, p->thread.fsindex);
 309         savesegment(es, p->thread.es);
 310         savesegment(ds, p->thread.ds);
 311
 312         if (unlikely(test_tsk_thread_flag(me, TIF_IO_BITMAP))) {
 313                 p->thread.io_bitmap_ptr = kmalloc(IO_BITMAP_BYTES, GFP_KERNEL);
 314                 if (!p->thread.io_bitmap_ptr) {
 315                         p->thread.io_bitmap_max = 0;
 316                         return -ENOMEM;
 317                 }
 318                 memcpy(p->thread.io_bitmap_ptr, me->thread.io_bitmap_ptr,
 319                                 IO_BITMAP_BYTES);
 320                 set_tsk_thread_flag(p, TIF_IO_BITMAP);
 321         }
 322
 323         /*
 324          * Set a new TLS for the child thread?
 325          */
 326         if (clone_flags & CLONE_SETTLS) {
 327 #ifdef CONFIG_IA32_EMULATION
 328                 if (test_thread_flag(TIF_IA32))
 329                         err = do_set_thread_area(p, -1,
 330                                 (struct user_desc __user *)childregs->si, 0);
 331                 else
 332 #endif
 333                         err = do_arch_prctl(p, ARCH_SET_FS, childregs->r8);
 334                 if (err)
 335                         goto out;
 336         }
 337
 338         ds_copy_thread(p, me);
 339
 340         clear_tsk_thread_flag(p, TIF_DEBUGCTLMSR);
 341         p->thread.debugctlmsr = 0;
 342
 343         err = 0;
 344 out:
 345         if (err && p->thread.io_bitmap_ptr) {
 346                 kfree(p->thread.io_bitmap_ptr);
 347                 p->thread.io_bitmap_max = 0;
 348         }
 349         return err;
 350 }
 351
 352 void
 353 start_thread(struct pt_regs *regs, unsigned long new_ip, unsigned long new_sp)
 354 {
 355         loadsegment(fs, 0);
 356         loadsegment(es, 0);
 357         loadsegment(ds, 0);
 358         load_gs_index(0);
 359         regs->ip                = new_ip;
 360         regs->sp                = new_sp;
 361         percpu_write(old_rsp, new_sp);
 362         regs->cs                = __USER_CS;
 363         regs->ss                = __USER_DS;
 364         regs->flags             = 0x200;
 365         set_fs(USER_DS);
 366         /*
 367          * Free the old FP and other extended state
 368          */
 369         free_thread_xstate(current);
 370 }
 371 EXPORT_SYMBOL_GPL(start_thread);
 372
 373 /*
 374  *      switch_to(x,y) should switch tasks from x to y.
 375  *
 376  * This could still be optimized:
 377  * - fold all the options into a flag word and test it with a single test.
 378  * - could test fs/gs bitsliced
 379  *
 380  * Kprobes not supported here. Set the probe on schedule instead.
 381  * Function graph tracer not supported too.
 382  */
 383 __notrace_funcgraph struct task_struct *
 384 __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
 385 {
 386         struct thread_struct *prev = &prev_p->thread;
 387         struct thread_struct *next = &next_p->thread;
 388         int cpu = smp_processor_id();
 389         struct tss_struct *tss = &per_cpu(init_tss, cpu);
 390         unsigned fsindex, gsindex;
 391
 392         /* we're going to use this soon, after a few expensive things */
 393         if (next_p->fpu_counter > 5)
 394                 prefetch(next->xstate);
 395
 396         /*
 397          * Reload esp0, LDT and the page table pointer:
 398          */
 399         load_sp0(tss, next);
 400
 401         /*
 402          * Switch DS and ES.
 403          * This won't pick up thread selector changes, but I guess that is ok.
 404          */
 405         savesegment(es, prev->es);
 406         if (unlikely(next->es | prev->es))
 407                 loadsegment(es, next->es);
 408
 409         savesegment(ds, prev->ds);
 410         if (unlikely(next->ds | prev->ds))
 411                 loadsegment(ds, next->ds);
 412
 413
 414         /* We must save %fs and %gs before load_TLS() because
 415          * %fs and %gs may be cleared by load_TLS().
 416          *
 417          * (e.g. xen_load_tls())
 418          */
 419         savesegment(fs, fsindex);
 420         savesegment(gs, gsindex);
 421
 422         load_TLS(next, cpu);
 423
 424         /*
 425          * Leave lazy mode, flushing any hypercalls made here.
 426          * This must be done before restoring TLS segments so
 427          * the GDT and LDT are properly updated, and must be
 428          * done before math_state_restore, so the TS bit is up
 429          * to date.
 430          */
 431         arch_leave_lazy_cpu_mode();
 432
 433         /*
 434          * Switch FS and GS.
 435          *
 436          * Segment register != 0 always requires a reload.  Also
 437          * reload when it has changed.  When prev process used 64bit
 438          * base always reload to avoid an information leak.
 439          */
 440         if (unlikely(fsindex | next->fsindex | prev->fs)) {
 441                 loadsegment(fs, next->fsindex);
 442                 /*
 443                  * Check if the user used a selector != 0; if yes
 444                  *  clear 64bit base, since overloaded base is always
 445                  *  mapped to the Null selector
 446                  */
 447                 if (fsindex)
 448                         prev->fs = 0;
 449         }
 450         /* when next process has a 64bit base use it */
 451         if (next->fs)
 452                 wrmsrl(MSR_FS_BASE, next->fs);
 453         prev->fsindex = fsindex;
 454
 455         if (unlikely(gsindex | next->gsindex | prev->gs)) {
 456                 load_gs_index(next->gsindex);
 457                 if (gsindex)
 458                         prev->gs = 0;
 459         }
 460         if (next->gs)
 461                 wrmsrl(MSR_KERNEL_GS_BASE, next->gs);
 462         prev->gsindex = gsindex;
 463
 464         /* Must be after DS reload */
 465         unlazy_fpu(prev_p);
 466
 467         /*
 468          * Switch the PDA and FPU contexts.
 469          */
 470         prev->usersp = percpu_read(old_rsp);
 471         percpu_write(old_rsp, next->usersp);
 472         percpu_write(current_task, next_p);
 473
 474         percpu_write(kernel_stack,
 475                   (unsigned long)task_stack_page(next_p) +
 476                   THREAD_SIZE - KERNEL_STACK_OFFSET);
 477
 478         /*
 479          * Now maybe reload the debug registers and handle I/O bitmaps
 480          */
 481         if (unlikely(task_thread_info(next_p)->flags & _TIF_WORK_CTXSW_NEXT ||
 482                      task_thread_info(prev_p)->flags & _TIF_WORK_CTXSW_PREV))
 483                 __switch_to_xtra(prev_p, next_p, tss);
 484
 485         /* If the task has used fpu the last 5 timeslices, just do a full
 486          * restore of the math state immediately to avoid the trap; the
 487          * chances of needing FPU soon are obviously high now
 488          *
 489          * tsk_used_math() checks prevent calling math_state_restore(),
 490          * which can sleep in the case of !tsk_used_math()
 491          */
 492         if (tsk_used_math(next_p) && next_p->fpu_counter > 5)
 493                 math_state_restore();
 494         return prev_p;
 495 }
 496
 497 /*
 498  * sys_execve() executes a new program.
 499  */
 500 asmlinkage
 501 long sys_execve(char __user *name, char __user * __user *argv,
 502                 char __user * __user *envp, struct pt_regs *regs)
 503 {
 504         long error;
 505         char *filename;
 506
 507         filename = getname(name);
 508         error = PTR_ERR(filename);
 509         if (IS_ERR(filename))
 510                 return error;
 511         error = do_execve(filename, argv, envp, regs);
 512         putname(filename);
 513         return error;
 514 }
 515
 516 void set_personality_64bit(void)
 517 {
 518         /* inherit personality from parent */
 519
 520         /* Make sure to be in 64bit mode */
 521         clear_thread_flag(TIF_IA32);
 522
 523         /* TBD: overwrites user setup. Should have two bits.
 524            But 64bit processes have always behaved this way,
 525            so it's not too bad. The main problem is just that
 526            32bit childs are affected again. */
 527         current->personality &= ~READ_IMPLIES_EXEC;
 528 }
 529
 530 asmlinkage long
 531 sys_clone(unsigned long clone_flags, unsigned long newsp,
 532           void __user *parent_tid, void __user *child_tid, struct pt_regs *regs)
 533 {
 534         if (!newsp)
 535                 newsp = regs->sp;
 536         return do_fork(clone_flags, newsp, regs, 0, parent_tid, child_tid);
 537 }
 538
 539 unsigned long get_wchan(struct task_struct *p)
 540 {
 541         unsigned long stack;
 542         u64 fp, ip;
 543         int count = 0;
 544
 545         if (!p || p == current || p->state == TASK_RUNNING)
 546                 return 0;
 547         stack = (unsigned long)task_stack_page(p);
 548         if (p->thread.sp < stack || p->thread.sp >= stack+THREAD_SIZE)
 549                 return 0;
 550         fp = *(u64 *)(p->thread.sp);
 551         do {
 552                 if (fp < (unsigned long)stack ||
 553                     fp >= (unsigned long)stack+THREAD_SIZE)
 554                         return 0;
 555                 ip = *(u64 *)(fp+8);
 556                 if (!in_sched_functions(ip))
 557                         return ip;
 558                 fp = *(u64 *)fp;
 559         } while (count++ < 16);
 560         return 0;
 561 }
 562
 563 long do_arch_prctl(struct task_struct *task, int code, unsigned long addr)
 564 {
 565         int ret = 0;
 566         int doit = task == current;
 567         int cpu;
 568
 569         switch (code) {
 570         case ARCH_SET_GS:
 571                 if (addr >= TASK_SIZE_OF(task))
 572                         return -EPERM;
 573                 cpu = get_cpu();
 574                 /* handle small bases via the GDT because that's faster to
 575                    switch. */
 576                 if (addr <= 0xffffffff) {
 577                         set_32bit_tls(task, GS_TLS, addr);
 578                         if (doit) {
 579                                 load_TLS(&task->thread, cpu);
 580                                 load_gs_index(GS_TLS_SEL);
 581                         }
 582                         task->thread.gsindex = GS_TLS_SEL;
 583                         task->thread.gs = 0;
 584                 } else {
 585                         task->thread.gsindex = 0;
 586                         task->thread.gs = addr;
 587                         if (doit) {
 588                                 load_gs_index(0);
 589                                 ret = checking_wrmsrl(MSR_KERNEL_GS_BASE, addr);
 590                         }
 591                 }
 592                 put_cpu();
 593                 break;
 594         case ARCH_SET_FS:
 595                 /* Not strictly needed for fs, but do it for symmetry
 596                    with gs */
 597                 if (addr >= TASK_SIZE_OF(task))
 598                         return -EPERM;
 599                 cpu = get_cpu();
 600                 /* handle small bases via the GDT because that's faster to
 601                    switch. */
 602                 if (addr <= 0xffffffff) {
 603                         set_32bit_tls(task, FS_TLS, addr);
 604                         if (doit) {
 605                                 load_TLS(&task->thread, cpu);
 606                                 loadsegment(fs, FS_TLS_SEL);
 607                         }
 608                         task->thread.fsindex = FS_TLS_SEL;
 609                         task->thread.fs = 0;
 610                 } else {
 611                         task->thread.fsindex = 0;
 612                         task->thread.fs = addr;
 613                         if (doit) {
 614                                 /* set the selector to 0 to not confuse
 615                                    __switch_to */
 616                                 loadsegment(fs, 0);
 617                                 ret = checking_wrmsrl(MSR_FS_BASE, addr);
 618                         }
 619                 }
 620                 put_cpu();
 621                 break;
 622         case ARCH_GET_FS: {
 623                 unsigned long base;
 624                 if (task->thread.fsindex == FS_TLS_SEL)
 625                         base = read_32bit_tls(task, FS_TLS);
 626                 else if (doit)
 627                         rdmsrl(MSR_FS_BASE, base);
 628                 else
 629                         base = task->thread.fs;
 630                 ret = put_user(base, (unsigned long __user *)addr);
 631                 break;
 632         }
 633         case ARCH_GET_GS: {
 634                 unsigned long base;
 635                 unsigned gsindex;
 636                 if (task->thread.gsindex == GS_TLS_SEL)
 637                         base = read_32bit_tls(task, GS_TLS);
 638                 else if (doit) {
 639                         savesegment(gs, gsindex);
 640                         if (gsindex)
 641                                 rdmsrl(MSR_KERNEL_GS_BASE, base);
 642                         else
 643                                 base = task->thread.gs;
 644                 } else
 645                         base = task->thread.gs;
 646                 ret = put_user(base, (unsigned long __user *)addr);
 647                 break;
 648         }
 649
 650         default:
 651                 ret = -EINVAL;
 652                 break;
 653         }
 654
 655         return ret;
 656 }
 657
 658 long sys_arch_prctl(int code, unsigned long addr)
 659 {
 660         return do_arch_prctl(current, code, addr);
 661 }
 662
 663 unsigned long arch_align_stack(unsigned long sp)
 664 {
 665         if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
 666                 sp -= get_random_int() % 8192;
 667         return sp & ~0xf;
 668 }
 669
 670 unsigned long arch_randomize_brk(struct mm_struct *mm)
 671 {
 672         unsigned long range_end = mm->brk + 0x02000000;
 673         return randomize_range(mm->brk, range_end, 0) ? : mm->brk;
 674 }