arch/arm/kernel/process.c

   1 /*
   2  *  linux/arch/arm/kernel/process.c
   3  *
   4  *  Copyright (C) 1996-2000 Russell King - Converted to ARM.
   5  *  Original Copyright (C) 1995  Linus Torvalds
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License version 2 as
   9  * published by the Free Software Foundation.
  10  */
  11 #include <stdarg.h>
  12
  13 #include <linux/export.h>
  14 #include <linux/sched.h>
  15 #include <linux/kernel.h>
  16 #include <linux/mm.h>
  17 #include <linux/stddef.h>
  18 #include <linux/unistd.h>
  19 #include <linux/user.h>
  20 #include <linux/delay.h>
  21 #include <linux/reboot.h>
  22 #include <linux/interrupt.h>
  23 #include <linux/kallsyms.h>
  24 #include <linux/init.h>
  25 #include <linux/cpu.h>
  26 #include <linux/elfcore.h>
  27 #include <linux/pm.h>
  28 #include <linux/tick.h>
  29 #include <linux/utsname.h>
  30 #include <linux/uaccess.h>
  31 #include <linux/random.h>
  32 #include <linux/hw_breakpoint.h>
  33 #include <linux/cpuidle.h>
  34 #include <linux/leds.h>
  35 #include <linux/console.h>
  36 #include <linux/mtk_ram_console.h>
  37
  38 #include <asm/cacheflush.h>
  39 #include <asm/idmap.h>
  40 #include <asm/processor.h>
  41 #include <asm/thread_notify.h>
  42 #include <asm/stacktrace.h>
  43 #include <asm/mach/time.h>
  44 #include <mach/system.h>
  45
  46 #ifdef CONFIG_CC_STACKPROTECTOR
  47 #include <linux/stackprotector.h>
  48 unsigned long __stack_chk_guard __read_mostly;
  49 EXPORT_SYMBOL(__stack_chk_guard);
  50 #endif
  51
  52 static const char *processor_modes[] = {
  53   "USER_26", "FIQ_26" , "IRQ_26" , "SVC_26" , "UK4_26" , "UK5_26" , "UK6_26" , "UK7_26" ,
  54   "UK8_26" , "UK9_26" , "UK10_26", "UK11_26", "UK12_26", "UK13_26", "UK14_26", "UK15_26",
  55   "USER_32", "FIQ_32" , "IRQ_32" , "SVC_32" , "UK4_32" , "UK5_32" , "UK6_32" , "ABT_32" ,
  56   "UK8_32" , "UK9_32" , "UK10_32", "UND_32" , "UK12_32", "UK13_32", "UK14_32", "SYS_32"
  57 };
  58
  59 static const char *isa_modes[] = {
  60   "ARM" , "Thumb" , "Jazelle", "ThumbEE"
  61 };
  62
  63 #ifdef CONFIG_SMP
  64 void arch_trigger_all_cpu_backtrace(void)
  65 {
  66         smp_send_all_cpu_backtrace();
  67 }
  68 #else
  69 void arch_trigger_all_cpu_backtrace(void)
  70 {
  71         dump_stack();
  72 }
  73 #endif
  74
  75 extern void call_with_stack(void (*fn)(void *), void *arg, void *sp);
  76 typedef void (*phys_reset_t)(unsigned long);
  77
  78 #ifdef CONFIG_ARM_FLUSH_CONSOLE_ON_RESTART
  79 void arm_machine_flush_console(void)
  80 {
  81         printk("\n");
  82         pr_emerg("Restarting %s\n", linux_banner);
  83         if (console_trylock()) {
  84                 console_unlock();
  85                 return;
  86         }
  87
  88         mdelay(50);
  89
  90         local_irq_disable();
  91         if (!console_trylock())
  92                 pr_emerg("arm_restart: Console was locked! Busting\n");
  93         else
  94                 pr_emerg("arm_restart: Console was locked!\n");
  95         console_unlock();
  96 }
  97 #else
  98 void arm_machine_flush_console(void)
  99 {
 100 }
 101 #endif
 102
 103 /*
 104  * A temporary stack to use for CPU reset. This is static so that we
 105  * don't clobber it with the identity mapping. When running with this
 106  * stack, any references to the current task *will not work* so you
 107  * should really do as little as possible before jumping to your reset
 108  * code.
 109  */
 110 static u64 soft_restart_stack[16];
 111
 112 void arm_machine_restart(char mode, const char *cmd)
 113 {
 114         /* Flush the console to make sure all the relevant messages make it
 115          * out to the console drivers */
 116         arm_machine_flush_console();
 117
 118         /* Disable interrupts first */
 119         local_irq_disable();
 120         local_fiq_disable();
 121
 122         /*
 123          * Tell the mm system that we are going to reboot -
 124          * we may need it to insert some 1:1 mappings so that
 125          * soft boot works.
 126          */
 127         setup_mm_for_reboot();
 128
 129         /* When l1 is disabled and l2 is enabled, the spinlock cannot get the lock,
 130          * so we need to disable the l2 as well. by Chia-Hao Hsu
 131          */
 132         outer_flush_all();
 133         outer_disable();
 134         outer_flush_all();
 135
 136         /* Clean and invalidate caches */
 137         flush_cache_all();
 138 #ifdef CONFIG_RESTART_DISABLE_CACHE
 139         /* Turn off caching */
 140  //       cpu_proc_fin();               // Don't turn off cach during reboot phase. CA15 have risk if turn off cach.
 141 #endif
 142         /* Push out any further dirty data, and ensure cache is empty */
 143         flush_cache_all();
 144
 145         /*
 146          * Now call the architecture specific reboot code.
 147          */
 148         arch_reset(mode, cmd);
 149
 150         /*
 151          * Whoops - the architecture was unable to reboot.
 152          * Tell the user!
 153          */
 154         mdelay(1000);
 155         printk("Reboot failed -- System halted\n");
 156         while (1);
 157 }
 158
 159 static void __soft_restart(void *addr)
 160 {
 161         phys_reset_t phys_reset;
 162
 163         /* Take out a flat memory mapping. */
 164         setup_mm_for_reboot();
 165
 166         /* Clean and invalidate caches */
 167         flush_cache_all();
 168
 169         /* Turn off caching */
 170         cpu_proc_fin();
 171
 172         /* Push out any further dirty data, and ensure cache is empty */
 173         flush_cache_all();
 174
 175         /* Switch to the identity mapping. */
 176         phys_reset = (phys_reset_t)(unsigned long)virt_to_phys(cpu_reset);
 177         phys_reset((unsigned long)addr);
 178
 179         /* Should never get here. */
 180         BUG();
 181 }
 182
 183 void soft_restart(unsigned long addr)
 184 {
 185         u64 *stack = soft_restart_stack + ARRAY_SIZE(soft_restart_stack);
 186
 187         /* Disable interrupts first */
 188         local_irq_disable();
 189         local_fiq_disable();
 190
 191         /* Disable the L2 if we're the last man standing. */
 192         if (num_online_cpus() == 1) {
 193                 outer_flush_all();
 194                 outer_disable();
 195         }
 196
 197         /* Change to the new stack and continue with the reset. */
 198         call_with_stack(__soft_restart, (void *)addr, (void *)stack);
 199
 200         /* Should never get here. */
 201         BUG();
 202 }
 203
 204 static void null_restart(char mode, const char *cmd)
 205 {
 206 }
 207
 208 /*
 209  * Function pointers to optional machine specific functions
 210  */
 211 void (*pm_power_off)(void);
 212 EXPORT_SYMBOL(pm_power_off);
 213
 214 void (*arm_pm_restart)(char str, const char *cmd) = null_restart;
 215 EXPORT_SYMBOL_GPL(arm_pm_restart);
 216
 217 /*
 218  * This is our default idle handler.
 219  */
 220
 221 void (*arm_pm_idle)(void);
 222
 223 static void default_idle(void)
 224 {
 225         if (arm_pm_idle)
 226                 arm_pm_idle();
 227         else
 228                 cpu_do_idle();
 229         local_irq_enable();
 230 }
 231
 232 void arch_cpu_idle_prepare(void)
 233 {
 234         local_fiq_enable();
 235 }
 236
 237 void arch_cpu_idle_enter(void)
 238 {
 239         idle_notifier_call_chain(IDLE_START);
 240         ledtrig_cpu(CPU_LED_IDLE_START);
 241 #ifdef CONFIG_PL310_ERRATA_769419
 242         wmb();
 243 #endif
 244 }
 245
 246 void arch_cpu_idle_exit(void)
 247 {
 248         ledtrig_cpu(CPU_LED_IDLE_END);
 249         idle_notifier_call_chain(IDLE_END);
 250 }
 251
 252 #ifdef CONFIG_HOTPLUG_CPU
 253 void arch_cpu_idle_dead(void)
 254 {
 255         cpu_die();
 256 }
 257 #endif
 258
 259 /*
 260  * Called from the core idle loop.
 261  */
 262 void arch_cpu_idle(void)
 263 {
 264         if (cpuidle_idle_call())
 265                 default_idle();
 266 }
 267
 268 static char reboot_mode = 'h';
 269
 270 int __init reboot_setup(char *str)
 271 {
 272         reboot_mode = str[0];
 273         return 1;
 274 }
 275
 276 __setup("reboot=", reboot_setup);
 277
 278 /*
 279  * Called by kexec, immediately prior to machine_kexec().
 280  *
 281  * This must completely disable all secondary CPUs; simply causing those CPUs
 282  * to execute e.g. a RAM-based pin loop is not sufficient. This allows the
 283  * kexec'd kernel to use any and all RAM as it sees fit, without having to
 284  * avoid any code or data used by any SW CPU pin loop. The CPU hotplug
 285  * functionality embodied in disable_nonboot_cpus() to achieve this.
 286  */
 287 void machine_shutdown(void)
 288 {
 289 #ifdef CONFIG_SMP
 290         /*
 291          * Disable preemption so we're guaranteed to
 292          * run to power off or reboot and prevent
 293          * the possibility of switching to another
 294          * thread that might wind up blocking on
 295          * one of the stopped CPUs.
 296          */
 297     printk("machine_shutdown: start, Proess(%s:%d)\n", current->comm, current->pid);
 298     dump_stack();
 299         preempt_disable();
 300 #endif
 301         disable_nonboot_cpus();
 302     printk("machine_shutdown: done\n");
 303 }
 304
 305 /*
 306  * Halting simply requires that the secondary CPUs stop performing any
 307  * activity (executing tasks, handling interrupts). smp_send_stop()
 308  * achieves this.
 309  */
 310 void machine_halt(void)
 311 {
 312         smp_send_stop();
 313
 314         local_irq_disable();
 315         while (1);
 316 }
 317
 318 extern int reboot_pid;
 319 /*
 320  * Power-off simply requires that the secondary CPUs stop performing any
 321  * activity (executing tasks, handling interrupts). smp_send_stop()
 322  * achieves this. When the system power is turned off, it will take all CPUs
 323  * with it.
 324  */
 325 void machine_power_off(void)
 326 {
 327         struct task_struct *tsk;
 328
 329         /* Disable interrupts first */
 330         local_irq_disable();
 331         local_fiq_disable();
 332
 333         smp_send_stop();
 334         if(reboot_pid > 1)
 335         {
 336                 tsk = find_task_by_vpid(reboot_pid);
 337                 if(tsk == NULL)
 338                         tsk = current;
 339                 dump_stack();
 340         }
 341         else
 342         {
 343                 tsk = current;
 344         }
 345
 346         if(tsk->real_parent)
 347         {
 348          if(tsk->real_parent->real_parent)
 349          {
 350            printk("machine_shutdown: start, Proess(%s:%d). father %s:%d. grandfather %s:%d.\n",
 351                 tsk->comm, tsk->pid,tsk->real_parent->comm,tsk->real_parent->pid,
 352                 tsk->real_parent->real_parent->comm,tsk->real_parent->real_parent->pid);
 353          }
 354          else
 355          {
 356            printk("machine_shutdown: start, Proess(%s:%d). father %s:%d.\n",
 357                 tsk->comm, tsk->pid,tsk->real_parent->comm,tsk->real_parent->pid);
 358          }
 359         }
 360         else
 361         {
 362           printk("machine_shutdown: start, Proess(%s:%d)\n", tsk->comm, tsk->pid);
 363         }
 364
 365 #ifdef CONFIG_MTK_EMMC_SUPPORT
 366         last_kmsg_store_to_emmc();
 367 #endif
 368
 369         if (pm_power_off)
 370                 pm_power_off();
 371 }
 372
 373 /*
 374  * Restart requires that the secondary CPUs stop performing any activity
 375  * while the primary CPU resets the system. Systems with a single CPU can
 376  * use soft_restart() as their machine descriptor's .restart hook, since that
 377  * will cause the only available CPU to reset. Systems with multiple CPUs must
 378  * provide a HW restart implementation, to ensure that all CPUs reset at once.
 379  * This is required so that any code running after reset on the primary CPU
 380  * doesn't have to co-ordinate with other CPUs to ensure they aren't still
 381  * executing pre-reset code, and using RAM that the primary CPU's code wishes
 382  * to use. Implementing such co-ordination would be essentially impossible.
 383  */
 384 void machine_restart(char *cmd)
 385 {
 386         struct task_struct *tsk;
 387         /* Disable interrupts first */
 388         local_irq_disable();
 389         local_fiq_disable();
 390
 391         smp_send_stop();
 392
 393         if(reboot_pid > 1)
 394         {
 395                 tsk = find_task_by_vpid(reboot_pid);
 396                 if(tsk == NULL)
 397                         tsk = current;
 398                 dump_stack();
 399         }
 400         else
 401         {
 402                 tsk = current;
 403         }
 404
 405         if(tsk->real_parent)
 406         {
 407          if(tsk->real_parent->real_parent)
 408          {
 409            printk("machine_shutdown: start, Proess(%s:%d). father %s:%d. grandfather %s:%d.\n",
 410                 tsk->comm, tsk->pid,tsk->real_parent->comm,tsk->real_parent->pid,
 411                 tsk->real_parent->real_parent->comm,tsk->real_parent->real_parent->pid);
 412          }
 413          else
 414          {
 415            printk("machine_shutdown: start, Proess(%s:%d). father %s:%d.\n",
 416                 tsk->comm, tsk->pid,tsk->real_parent->comm,tsk->real_parent->pid);
 417          }
 418         }
 419         else
 420         {
 421           printk("machine_shutdown: start, Proess(%s:%d)\n", tsk->comm, tsk->pid);
 422         }
 423
 424         /* Flush the console to make sure all the relevant messages make it
 425          * out to the console drivers */
 426         arm_machine_flush_console();
 427
 428         arm_pm_restart(reboot_mode, cmd);
 429
 430         /* Give a grace period for failure to restart of 1s */
 431         mdelay(1000);
 432
 433         /* Whoops - the platform was unable to reboot. Tell the user! */
 434         printk("Reboot failed -- System halted\n");
 435         local_irq_disable();
 436         while (1);
 437 }
 438
 439 /*
 440  * dump a block of kernel memory from around the given address
 441  */
 442 static void show_data(unsigned long addr, int nbytes, const char *name)
 443 {
 444         int     i, j;
 445         int     nlines;
 446         u32     *p;
 447
 448         /*
 449          * don't attempt to dump non-kernel addresses or
 450          * values that are probably just small negative numbers
 451          */
 452         if (addr < PAGE_OFFSET || addr > -256UL)
 453                 return;
 454
 455         printk("\n%s: %#lx:\n", name, addr);
 456
 457         /*
 458          * round address down to a 32 bit boundary
 459          * and always dump a multiple of 32 bytes
 460          */
 461         p = (u32 *)(addr & ~(sizeof(u32) - 1));
 462         nbytes += (addr & (sizeof(u32) - 1));
 463         nlines = (nbytes + 31) / 32;
 464
 465
 466         for (i = 0; i < nlines; i++) {
 467                 /*
 468                  * just display low 16 bits of address to keep
 469                  * each line of the dump < 80 characters
 470                  */
 471                 printk("%04lx ", (unsigned long)p & 0xffff);
 472                 for (j = 0; j < 8; j++) {
 473                         u32     data;
 474                         if (probe_kernel_address(p, data)) {
 475                                 printk(" ********");
 476                         } else {
 477                                 printk(" %08x", data);
 478                         }
 479                         ++p;
 480                 }
 481                 printk("\n");
 482         }
 483 }
 484
 485 static void show_extra_register_data(struct pt_regs *regs, int nbytes)
 486 {
 487         mm_segment_t fs;
 488
 489         fs = get_fs();
 490         set_fs(KERNEL_DS);
 491         show_data(regs->ARM_pc - nbytes, nbytes * 2, "PC");
 492         show_data(regs->ARM_lr - nbytes, nbytes * 2, "LR");
 493         show_data(regs->ARM_sp - nbytes, nbytes * 2, "SP");
 494         show_data(regs->ARM_ip - nbytes, nbytes * 2, "IP");
 495         show_data(regs->ARM_fp - nbytes, nbytes * 2, "FP");
 496         show_data(regs->ARM_r0 - nbytes, nbytes * 2, "R0");
 497         show_data(regs->ARM_r1 - nbytes, nbytes * 2, "R1");
 498         show_data(regs->ARM_r2 - nbytes, nbytes * 2, "R2");
 499         show_data(regs->ARM_r3 - nbytes, nbytes * 2, "R3");
 500         show_data(regs->ARM_r4 - nbytes, nbytes * 2, "R4");
 501         show_data(regs->ARM_r5 - nbytes, nbytes * 2, "R5");
 502         show_data(regs->ARM_r6 - nbytes, nbytes * 2, "R6");
 503         show_data(regs->ARM_r7 - nbytes, nbytes * 2, "R7");
 504         show_data(regs->ARM_r8 - nbytes, nbytes * 2, "R8");
 505         show_data(regs->ARM_r9 - nbytes, nbytes * 2, "R9");
 506         show_data(regs->ARM_r10 - nbytes, nbytes * 2, "R10");
 507         set_fs(fs);
 508 }
 509
 510 void __show_regs(struct pt_regs *regs)
 511 {
 512         unsigned long flags;
 513         char buf[64];
 514
 515         show_regs_print_info(KERN_DEFAULT);
 516
 517         print_symbol("PC is at %s\n", instruction_pointer(regs));
 518         print_symbol("LR is at %s\n", regs->ARM_lr);
 519         printk("pc : [<%08lx>]    lr : [<%08lx>]    psr: %08lx\n"
 520                "sp : %08lx  ip : %08lx  fp : %08lx\n",
 521                 regs->ARM_pc, regs->ARM_lr, regs->ARM_cpsr,
 522                 regs->ARM_sp, regs->ARM_ip, regs->ARM_fp);
 523         printk("r10: %08lx  r9 : %08lx  r8 : %08lx\n",
 524                 regs->ARM_r10, regs->ARM_r9,
 525                 regs->ARM_r8);
 526         printk("r7 : %08lx  r6 : %08lx  r5 : %08lx  r4 : %08lx\n",
 527                 regs->ARM_r7, regs->ARM_r6,
 528                 regs->ARM_r5, regs->ARM_r4);
 529         printk("r3 : %08lx  r2 : %08lx  r1 : %08lx  r0 : %08lx\n",
 530                 regs->ARM_r3, regs->ARM_r2,
 531                 regs->ARM_r1, regs->ARM_r0);
 532
 533         flags = regs->ARM_cpsr;
 534         buf[0] = flags & PSR_N_BIT ? 'N' : 'n';
 535         buf[1] = flags & PSR_Z_BIT ? 'Z' : 'z';
 536         buf[2] = flags & PSR_C_BIT ? 'C' : 'c';
 537         buf[3] = flags & PSR_V_BIT ? 'V' : 'v';
 538         buf[4] = '\0';
 539
 540         printk("Flags: %s  IRQs o%s  FIQs o%s  Mode %s  ISA %s  Segment %s\n",
 541                 buf, interrupts_enabled(regs) ? "n" : "ff",
 542                 fast_interrupts_enabled(regs) ? "n" : "ff",
 543                 processor_modes[processor_mode(regs)],
 544                 isa_modes[isa_mode(regs)],
 545                 get_fs() == get_ds() ? "kernel" : "user");
 546 #ifdef CONFIG_CPU_CP15
 547         {
 548                 unsigned int ctrl;
 549
 550                 buf[0] = '\0';
 551 #ifdef CONFIG_CPU_CP15_MMU
 552                 {
 553                         unsigned int transbase, dac;
 554                         asm("mrc p15, 0, %0, c2, c0\n\t"
 555                             "mrc p15, 0, %1, c3, c0\n"
 556                             : "=r" (transbase), "=r" (dac));
 557                         snprintf(buf, sizeof(buf), "  Table: %08x  DAC: %08x",
 558                                 transbase, dac);
 559                 }
 560 #endif
 561                 asm("mrc p15, 0, %0, c1, c0\n" : "=r" (ctrl));
 562
 563                 printk("Control: %08x%s\n", ctrl, buf);
 564         }
 565 #endif
 566
 567         show_extra_register_data(regs, 128);
 568 }
 569
 570 void show_regs(struct pt_regs * regs)
 571 {
 572         printk("\n");
 573         __show_regs(regs);
 574         dump_stack();
 575 }
 576
 577 ATOMIC_NOTIFIER_HEAD(thread_notify_head);
 578
 579 EXPORT_SYMBOL_GPL(thread_notify_head);
 580
 581 /*
 582  * Free current thread data structures etc..
 583  */
 584 void exit_thread(void)
 585 {
 586         thread_notify(THREAD_NOTIFY_EXIT, current_thread_info());
 587 }
 588
 589 void flush_thread(void)
 590 {
 591         struct thread_info *thread = current_thread_info();
 592         struct task_struct *tsk = current;
 593
 594         flush_ptrace_hw_breakpoint(tsk);
 595
 596         memset(thread->used_cp, 0, sizeof(thread->used_cp));
 597         memset(&tsk->thread.debug, 0, sizeof(struct debug_info));
 598         memset(&thread->fpstate, 0, sizeof(union fp_state));
 599
 600         thread_notify(THREAD_NOTIFY_FLUSH, thread);
 601 }
 602
 603 void release_thread(struct task_struct *dead_task)
 604 {
 605 }
 606
 607 asmlinkage void ret_from_fork(void) __asm__("ret_from_fork");
 608
 609 int
 610 copy_thread(unsigned long clone_flags, unsigned long stack_start,
 611             unsigned long stk_sz, struct task_struct *p)
 612 {
 613         struct thread_info *thread = task_thread_info(p);
 614         struct pt_regs *childregs = task_pt_regs(p);
 615
 616         memset(&thread->cpu_context, 0, sizeof(struct cpu_context_save));
 617
 618         if (likely(!(p->flags & PF_KTHREAD))) {
 619                 *childregs = *current_pt_regs();
 620                 childregs->ARM_r0 = 0;
 621                 if (stack_start)
 622                         childregs->ARM_sp = stack_start;
 623         } else {
 624                 memset(childregs, 0, sizeof(struct pt_regs));
 625                 thread->cpu_context.r4 = stk_sz;
 626                 thread->cpu_context.r5 = stack_start;
 627                 childregs->ARM_cpsr = SVC_MODE;
 628         }
 629         thread->cpu_context.pc = (unsigned long)ret_from_fork;
 630         thread->cpu_context.sp = (unsigned long)childregs;
 631
 632         clear_ptrace_hw_breakpoint(p);
 633
 634         if (clone_flags & CLONE_SETTLS)
 635                 thread->tp_value = childregs->ARM_r3;
 636
 637         thread_notify(THREAD_NOTIFY_COPY, thread);
 638
 639         return 0;
 640 }
 641
 642 /*
 643  * Fill in the task's elfregs structure for a core dump.
 644  */
 645 int dump_task_regs(struct task_struct *t, elf_gregset_t *elfregs)
 646 {
 647         elf_core_copy_regs(elfregs, task_pt_regs(t));
 648         return 1;
 649 }
 650
 651 /*
 652  * fill in the fpe structure for a core dump...
 653  */
 654 int dump_fpu (struct pt_regs *regs, struct user_fp *fp)
 655 {
 656         struct thread_info *thread = current_thread_info();
 657         int used_math = thread->used_cp[1] | thread->used_cp[2];
 658
 659         if (used_math)
 660                 memcpy(fp, &thread->fpstate.soft, sizeof (*fp));
 661
 662         return used_math != 0;
 663 }
 664 EXPORT_SYMBOL(dump_fpu);
 665
 666 unsigned long get_wchan(struct task_struct *p)
 667 {
 668         struct stackframe frame;
 669         unsigned long stack_page;
 670         int count = 0;
 671         if (!p || p == current || p->state == TASK_RUNNING)
 672                 return 0;
 673
 674         frame.fp = thread_saved_fp(p);
 675         frame.sp = thread_saved_sp(p);
 676         frame.lr = 0;                   /* recovered from the stack */
 677         frame.pc = thread_saved_pc(p);
 678         stack_page = (unsigned long)task_stack_page(p);
 679         do {
 680                 if (frame.sp < stack_page ||
 681                     frame.sp >= stack_page + THREAD_SIZE ||
 682                     unwind_frame(&frame) < 0)
 683                         return 0;
 684                 if (!in_sched_functions(frame.pc))
 685                         return frame.pc;
 686         } while (count ++ < 16);
 687         return 0;
 688 }
 689
 690 unsigned long arch_randomize_brk(struct mm_struct *mm)
 691 {
 692         unsigned long range_end = mm->brk + 0x02000000;
 693         return randomize_range(mm->brk, range_end, 0) ? : mm->brk;
 694 }
 695
 696 #ifdef CONFIG_MMU
 697 #ifdef CONFIG_KUSER_HELPERS
 698 /*
 699  * The vectors page is always readable from user space for the
 700  * atomic helpers. Insert it into the gate_vma so that it is visible
 701  * through ptrace and /proc/<pid>/mem.
 702  */
 703 static struct vm_area_struct gate_vma = {
 704         .vm_start       = 0xffff0000,
 705         .vm_end         = 0xffff0000 + PAGE_SIZE,
 706         .vm_flags       = VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYEXEC,
 707 };
 708
 709 static int __init gate_vma_init(void)
 710 {
 711         gate_vma.vm_page_prot = PAGE_READONLY_EXEC;
 712         return 0;
 713 }
 714 arch_initcall(gate_vma_init);
 715
 716 struct vm_area_struct *get_gate_vma(struct mm_struct *mm)
 717 {
 718         return &gate_vma;
 719 }
 720
 721 int in_gate_area(struct mm_struct *mm, unsigned long addr)
 722 {
 723         return (addr >= gate_vma.vm_start) && (addr < gate_vma.vm_end);
 724 }
 725
 726 int in_gate_area_no_mm(unsigned long addr)
 727 {
 728         return in_gate_area(NULL, addr);
 729 }
 730 #define is_gate_vma(vma)        ((vma) == &gate_vma)
 731 #else
 732 #define is_gate_vma(vma)        0
 733 #endif
 734
 735 const char *arch_vma_name(struct vm_area_struct *vma)
 736 {
 737         return is_gate_vma(vma) ? "[vectors]" :
 738                 (vma->vm_mm && vma->vm_start == vma->vm_mm->context.sigpage) ?
 739                  "[sigpage]" : NULL;
 740 }
 741
 742 static struct page *signal_page;
 743 extern struct page *get_signal_page(void);
 744
 745 int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
 746 {
 747         struct mm_struct *mm = current->mm;
 748         unsigned long addr;
 749         int ret;
 750
 751         if (!signal_page)
 752                 signal_page = get_signal_page();
 753         if (!signal_page)
 754                 return -ENOMEM;
 755
 756         down_write(&mm->mmap_sem);
 757         addr = get_unmapped_area(NULL, 0, PAGE_SIZE, 0, 0);
 758         if (IS_ERR_VALUE(addr)) {
 759                 ret = addr;
 760                 goto up_fail;
 761         }
 762
 763         ret = install_special_mapping(mm, addr, PAGE_SIZE,
 764                 VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC,
 765                 &signal_page);
 766
 767         if (ret == 0)
 768                 mm->context.sigpage = addr;
 769
 770  up_fail:
 771         up_write(&mm->mmap_sem);
 772         return ret;
 773 }
 774 #endif