arch/powerpc/kernel/process.c

   1 /*
   2  *  Derived from "arch/i386/kernel/process.c"
   3  *    Copyright (C) 1995  Linus Torvalds
   4  *
   5  *  Updated and modified by Cort Dougan (cort@cs.nmt.edu) and
   6  *  Paul Mackerras (paulus@cs.anu.edu.au)
   7  *
   8  *  PowerPC version
   9  *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
  10  *
  11  *  This program is free software; you can redistribute it and/or
  12  *  modify it under the terms of the GNU General Public License
  13  *  as published by the Free Software Foundation; either version
  14  *  2 of the License, or (at your option) any later version.
  15  */
  16
  17 #include <linux/errno.h>
  18 #include <linux/sched.h>
  19 #include <linux/kernel.h>
  20 #include <linux/mm.h>
  21 #include <linux/smp.h>
  22 #include <linux/stddef.h>
  23 #include <linux/unistd.h>
  24 #include <linux/ptrace.h>
  25 #include <linux/slab.h>
  26 #include <linux/user.h>
  27 #include <linux/elf.h>
  28 #include <linux/init.h>
  29 #include <linux/prctl.h>
  30 #include <linux/init_task.h>
  31 #include <linux/module.h>
  32 #include <linux/kallsyms.h>
  33 #include <linux/mqueue.h>
  34 #include <linux/hardirq.h>
  35 #include <linux/utsname.h>
  36 #include <linux/ftrace.h>
  37 #include <linux/kernel_stat.h>
  38 #include <linux/personality.h>
  39 #include <linux/random.h>
  40 #include <linux/hw_breakpoint.h>
  41
  42 #include <asm/pgtable.h>
  43 #include <asm/uaccess.h>
  44 #include <asm/system.h>
  45 #include <asm/io.h>
  46 #include <asm/processor.h>
  47 #include <asm/mmu.h>
  48 #include <asm/prom.h>
  49 #include <asm/machdep.h>
  50 #include <asm/time.h>
  51 #include <asm/syscalls.h>
  52 #ifdef CONFIG_PPC64
  53 #include <asm/firmware.h>
  54 #endif
  55 #include <linux/kprobes.h>
  56 #include <linux/kdebug.h>
  57
  58 extern unsigned long _get_SP(void);
  59
  60 #ifndef CONFIG_SMP
  61 struct task_struct *last_task_used_math = NULL;
  62 struct task_struct *last_task_used_altivec = NULL;
  63 struct task_struct *last_task_used_vsx = NULL;
  64 struct task_struct *last_task_used_spe = NULL;
  65 #endif
  66
  67 /*
  68  * Make sure the floating-point register state in the
  69  * the thread_struct is up to date for task tsk.
  70  */
  71 void flush_fp_to_thread(struct task_struct *tsk)
  72 {
  73         if (tsk->thread.regs) {
  74                 /*
  75                  * We need to disable preemption here because if we didn't,
  76                  * another process could get scheduled after the regs->msr
  77                  * test but before we have finished saving the FP registers
  78                  * to the thread_struct.  That process could take over the
  79                  * FPU, and then when we get scheduled again we would store
  80                  * bogus values for the remaining FP registers.
  81                  */
  82                 preempt_disable();
  83                 if (tsk->thread.regs->msr & MSR_FP) {
  84 #ifdef CONFIG_SMP
  85                         /*
  86                          * This should only ever be called for current or
  87                          * for a stopped child process.  Since we save away
  88                          * the FP register state on context switch on SMP,
  89                          * there is something wrong if a stopped child appears
  90                          * to still have its FP state in the CPU registers.
  91                          */
  92                         BUG_ON(tsk != current);
  93 #endif
  94                         giveup_fpu(tsk);
  95                 }
  96                 preempt_enable();
  97         }
  98 }
  99
 100 void enable_kernel_fp(void)
 101 {
 102         WARN_ON(preemptible());
 103
 104 #ifdef CONFIG_SMP
 105         if (current->thread.regs && (current->thread.regs->msr & MSR_FP))
 106                 giveup_fpu(current);
 107         else
 108                 giveup_fpu(NULL);       /* just enables FP for kernel */
 109 #else
 110         giveup_fpu(last_task_used_math);
 111 #endif /* CONFIG_SMP */
 112 }
 113 EXPORT_SYMBOL(enable_kernel_fp);
 114
 115 #ifdef CONFIG_ALTIVEC
 116 void enable_kernel_altivec(void)
 117 {
 118         WARN_ON(preemptible());
 119
 120 #ifdef CONFIG_SMP
 121         if (current->thread.regs && (current->thread.regs->msr & MSR_VEC))
 122                 giveup_altivec(current);
 123         else
 124                 giveup_altivec(NULL);   /* just enable AltiVec for kernel - force */
 125 #else
 126         giveup_altivec(last_task_used_altivec);
 127 #endif /* CONFIG_SMP */
 128 }
 129 EXPORT_SYMBOL(enable_kernel_altivec);
 130
 131 /*
 132  * Make sure the VMX/Altivec register state in the
 133  * the thread_struct is up to date for task tsk.
 134  */
 135 void flush_altivec_to_thread(struct task_struct *tsk)
 136 {
 137         if (tsk->thread.regs) {
 138                 preempt_disable();
 139                 if (tsk->thread.regs->msr & MSR_VEC) {
 140 #ifdef CONFIG_SMP
 141                         BUG_ON(tsk != current);
 142 #endif
 143                         giveup_altivec(tsk);
 144                 }
 145                 preempt_enable();
 146         }
 147 }
 148 #endif /* CONFIG_ALTIVEC */
 149
 150 #ifdef CONFIG_VSX
 151 #if 0
 152 /* not currently used, but some crazy RAID module might want to later */
 153 void enable_kernel_vsx(void)
 154 {
 155         WARN_ON(preemptible());
 156
 157 #ifdef CONFIG_SMP
 158         if (current->thread.regs && (current->thread.regs->msr & MSR_VSX))
 159                 giveup_vsx(current);
 160         else
 161                 giveup_vsx(NULL);       /* just enable vsx for kernel - force */
 162 #else
 163         giveup_vsx(last_task_used_vsx);
 164 #endif /* CONFIG_SMP */
 165 }
 166 EXPORT_SYMBOL(enable_kernel_vsx);
 167 #endif
 168
 169 void giveup_vsx(struct task_struct *tsk)
 170 {
 171         giveup_fpu(tsk);
 172         giveup_altivec(tsk);
 173         __giveup_vsx(tsk);
 174 }
 175
 176 void flush_vsx_to_thread(struct task_struct *tsk)
 177 {
 178         if (tsk->thread.regs) {
 179                 preempt_disable();
 180                 if (tsk->thread.regs->msr & MSR_VSX) {
 181 #ifdef CONFIG_SMP
 182                         BUG_ON(tsk != current);
 183 #endif
 184                         giveup_vsx(tsk);
 185                 }
 186                 preempt_enable();
 187         }
 188 }
 189 #endif /* CONFIG_VSX */
 190
 191 #ifdef CONFIG_SPE
 192
 193 void enable_kernel_spe(void)
 194 {
 195         WARN_ON(preemptible());
 196
 197 #ifdef CONFIG_SMP
 198         if (current->thread.regs && (current->thread.regs->msr & MSR_SPE))
 199                 giveup_spe(current);
 200         else
 201                 giveup_spe(NULL);       /* just enable SPE for kernel - force */
 202 #else
 203         giveup_spe(last_task_used_spe);
 204 #endif /* __SMP __ */
 205 }
 206 EXPORT_SYMBOL(enable_kernel_spe);
 207
 208 void flush_spe_to_thread(struct task_struct *tsk)
 209 {
 210         if (tsk->thread.regs) {
 211                 preempt_disable();
 212                 if (tsk->thread.regs->msr & MSR_SPE) {
 213 #ifdef CONFIG_SMP
 214                         BUG_ON(tsk != current);
 215 #endif
 216                         giveup_spe(tsk);
 217                 }
 218                 preempt_enable();
 219         }
 220 }
 221 #endif /* CONFIG_SPE */
 222
 223 #ifndef CONFIG_SMP
 224 /*
 225  * If we are doing lazy switching of CPU state (FP, altivec or SPE),
 226  * and the current task has some state, discard it.
 227  */
 228 void discard_lazy_cpu_state(void)
 229 {
 230         preempt_disable();
 231         if (last_task_used_math == current)
 232                 last_task_used_math = NULL;
 233 #ifdef CONFIG_ALTIVEC
 234         if (last_task_used_altivec == current)
 235                 last_task_used_altivec = NULL;
 236 #endif /* CONFIG_ALTIVEC */
 237 #ifdef CONFIG_VSX
 238         if (last_task_used_vsx == current)
 239                 last_task_used_vsx = NULL;
 240 #endif /* CONFIG_VSX */
 241 #ifdef CONFIG_SPE
 242         if (last_task_used_spe == current)
 243                 last_task_used_spe = NULL;
 244 #endif
 245         preempt_enable();
 246 }
 247 #endif /* CONFIG_SMP */
 248
 249 #ifdef CONFIG_PPC_ADV_DEBUG_REGS
 250 void do_send_trap(struct pt_regs *regs, unsigned long address,
 251                   unsigned long error_code, int signal_code, int breakpt)
 252 {
 253         siginfo_t info;
 254
 255         if (notify_die(DIE_DABR_MATCH, "dabr_match", regs, error_code,
 256                         11, SIGSEGV) == NOTIFY_STOP)
 257                 return;
 258
 259         /* Deliver the signal to userspace */
 260         info.si_signo = SIGTRAP;
 261         info.si_errno = breakpt;        /* breakpoint or watchpoint id */
 262         info.si_code = signal_code;
 263         info.si_addr = (void __user *)address;
 264         force_sig_info(SIGTRAP, &info, current);
 265 }
 266 #else   /* !CONFIG_PPC_ADV_DEBUG_REGS */
 267 void do_dabr(struct pt_regs *regs, unsigned long address,
 268                     unsigned long error_code)
 269 {
 270         siginfo_t info;
 271
 272         if (notify_die(DIE_DABR_MATCH, "dabr_match", regs, error_code,
 273                         11, SIGSEGV) == NOTIFY_STOP)
 274                 return;
 275
 276         if (debugger_dabr_match(regs))
 277                 return;
 278
 279         /* Clear the DABR */
 280         set_dabr(0);
 281
 282         /* Deliver the signal to userspace */
 283         info.si_signo = SIGTRAP;
 284         info.si_errno = 0;
 285         info.si_code = TRAP_HWBKPT;
 286         info.si_addr = (void __user *)address;
 287         force_sig_info(SIGTRAP, &info, current);
 288 }
 289 #endif  /* CONFIG_PPC_ADV_DEBUG_REGS */
 290
 291 static DEFINE_PER_CPU(unsigned long, current_dabr);
 292
 293 #ifdef CONFIG_PPC_ADV_DEBUG_REGS
 294 /*
 295  * Set the debug registers back to their default "safe" values.
 296  */
 297 static void set_debug_reg_defaults(struct thread_struct *thread)
 298 {
 299         thread->iac1 = thread->iac2 = 0;
 300 #if CONFIG_PPC_ADV_DEBUG_IACS > 2
 301         thread->iac3 = thread->iac4 = 0;
 302 #endif
 303         thread->dac1 = thread->dac2 = 0;
 304 #if CONFIG_PPC_ADV_DEBUG_DVCS > 0
 305         thread->dvc1 = thread->dvc2 = 0;
 306 #endif
 307         thread->dbcr0 = 0;
 308 #ifdef CONFIG_BOOKE
 309         /*
 310          * Force User/Supervisor bits to b11 (user-only MSR[PR]=1)
 311          */
 312         thread->dbcr1 = DBCR1_IAC1US | DBCR1_IAC2US |   \
 313                         DBCR1_IAC3US | DBCR1_IAC4US;
 314         /*
 315          * Force Data Address Compare User/Supervisor bits to be User-only
 316          * (0b11 MSR[PR]=1) and set all other bits in DBCR2 register to be 0.
 317          */
 318         thread->dbcr2 = DBCR2_DAC1US | DBCR2_DAC2US;
 319 #else
 320         thread->dbcr1 = 0;
 321 #endif
 322 }
 323
 324 static void prime_debug_regs(struct thread_struct *thread)
 325 {
 326         mtspr(SPRN_IAC1, thread->iac1);
 327         mtspr(SPRN_IAC2, thread->iac2);
 328 #if CONFIG_PPC_ADV_DEBUG_IACS > 2
 329         mtspr(SPRN_IAC3, thread->iac3);
 330         mtspr(SPRN_IAC4, thread->iac4);
 331 #endif
 332         mtspr(SPRN_DAC1, thread->dac1);
 333         mtspr(SPRN_DAC2, thread->dac2);
 334 #if CONFIG_PPC_ADV_DEBUG_DVCS > 0
 335         mtspr(SPRN_DVC1, thread->dvc1);
 336         mtspr(SPRN_DVC2, thread->dvc2);
 337 #endif
 338         mtspr(SPRN_DBCR0, thread->dbcr0);
 339         mtspr(SPRN_DBCR1, thread->dbcr1);
 340 #ifdef CONFIG_BOOKE
 341         mtspr(SPRN_DBCR2, thread->dbcr2);
 342 #endif
 343 }
 344 /*
 345  * Unless neither the old or new thread are making use of the
 346  * debug registers, set the debug registers from the values
 347  * stored in the new thread.
 348  */
 349 static void switch_booke_debug_regs(struct thread_struct *new_thread)
 350 {
 351         if ((current->thread.dbcr0 & DBCR0_IDM)
 352                 || (new_thread->dbcr0 & DBCR0_IDM))
 353                         prime_debug_regs(new_thread);
 354 }
 355 #else   /* !CONFIG_PPC_ADV_DEBUG_REGS */
 356 static void set_debug_reg_defaults(struct thread_struct *thread)
 357 {
 358         if (thread->dabr) {
 359                 thread->dabr = 0;
 360                 set_dabr(0);
 361         }
 362 }
 363 #endif  /* CONFIG_PPC_ADV_DEBUG_REGS */
 364
 365 int set_dabr(unsigned long dabr)
 366 {
 367         __get_cpu_var(current_dabr) = dabr;
 368
 369         if (ppc_md.set_dabr)
 370                 return ppc_md.set_dabr(dabr);
 371
 372         /* XXX should we have a CPU_FTR_HAS_DABR ? */
 373 #ifdef CONFIG_PPC_ADV_DEBUG_REGS
 374         mtspr(SPRN_DAC1, dabr);
 375 #ifdef CONFIG_PPC_47x
 376         isync();
 377 #endif
 378 #elif defined(CONFIG_PPC_BOOK3S)
 379         mtspr(SPRN_DABR, dabr);
 380 #endif
 381
 382
 383         return 0;
 384 }
 385
 386 #ifdef CONFIG_PPC64
 387 DEFINE_PER_CPU(struct cpu_usage, cpu_usage_array);
 388 #endif
 389
 390 struct task_struct *__switch_to(struct task_struct *prev,
 391         struct task_struct *new)
 392 {
 393         struct thread_struct *new_thread, *old_thread;
 394         unsigned long flags;
 395         struct task_struct *last;
 396
 397 #ifdef CONFIG_SMP
 398         /* avoid complexity of lazy save/restore of fpu
 399          * by just saving it every time we switch out if
 400          * this task used the fpu during the last quantum.
 401          *
 402          * If it tries to use the fpu again, it'll trap and
 403          * reload its fp regs.  So we don't have to do a restore
 404          * every switch, just a save.
 405          *  -- Cort
 406          */
 407         if (prev->thread.regs && (prev->thread.regs->msr & MSR_FP))
 408                 giveup_fpu(prev);
 409 #ifdef CONFIG_ALTIVEC
 410         /*
 411          * If the previous thread used altivec in the last quantum
 412          * (thus changing altivec regs) then save them.
 413          * We used to check the VRSAVE register but not all apps
 414          * set it, so we don't rely on it now (and in fact we need
 415          * to save & restore VSCR even if VRSAVE == 0).  -- paulus
 416          *
 417          * On SMP we always save/restore altivec regs just to avoid the
 418          * complexity of changing processors.
 419          *  -- Cort
 420          */
 421         if (prev->thread.regs && (prev->thread.regs->msr & MSR_VEC))
 422                 giveup_altivec(prev);
 423 #endif /* CONFIG_ALTIVEC */
 424 #ifdef CONFIG_VSX
 425         if (prev->thread.regs && (prev->thread.regs->msr & MSR_VSX))
 426                 /* VMX and FPU registers are already save here */
 427                 __giveup_vsx(prev);
 428 #endif /* CONFIG_VSX */
 429 #ifdef CONFIG_SPE
 430         /*
 431          * If the previous thread used spe in the last quantum
 432          * (thus changing spe regs) then save them.
 433          *
 434          * On SMP we always save/restore spe regs just to avoid the
 435          * complexity of changing processors.
 436          */
 437         if ((prev->thread.regs && (prev->thread.regs->msr & MSR_SPE)))
 438                 giveup_spe(prev);
 439 #endif /* CONFIG_SPE */
 440
 441 #else  /* CONFIG_SMP */
 442 #ifdef CONFIG_ALTIVEC
 443         /* Avoid the trap.  On smp this this never happens since
 444          * we don't set last_task_used_altivec -- Cort
 445          */
 446         if (new->thread.regs && last_task_used_altivec == new)
 447                 new->thread.regs->msr |= MSR_VEC;
 448 #endif /* CONFIG_ALTIVEC */
 449 #ifdef CONFIG_VSX
 450         if (new->thread.regs && last_task_used_vsx == new)
 451                 new->thread.regs->msr |= MSR_VSX;
 452 #endif /* CONFIG_VSX */
 453 #ifdef CONFIG_SPE
 454         /* Avoid the trap.  On smp this this never happens since
 455          * we don't set last_task_used_spe
 456          */
 457         if (new->thread.regs && last_task_used_spe == new)
 458                 new->thread.regs->msr |= MSR_SPE;
 459 #endif /* CONFIG_SPE */
 460
 461 #endif /* CONFIG_SMP */
 462
 463 #ifdef CONFIG_PPC_ADV_DEBUG_REGS
 464         switch_booke_debug_regs(&new->thread);
 465 #else
 466 /*
 467  * For PPC_BOOK3S_64, we use the hw-breakpoint interfaces that would
 468  * schedule DABR
 469  */
 470 #ifndef CONFIG_HAVE_HW_BREAKPOINT
 471         if (unlikely(__get_cpu_var(current_dabr) != new->thread.dabr))
 472                 set_dabr(new->thread.dabr);
 473 #endif /* CONFIG_HAVE_HW_BREAKPOINT */
 474 #endif
 475
 476
 477         new_thread = &new->thread;
 478         old_thread = &current->thread;
 479
 480 #if defined(CONFIG_PPC_BOOK3E_64)
 481         /* XXX Current Book3E code doesn't deal with kernel side DBCR0,
 482          * we always hold the user values, so we set it now.
 483          *
 484          * However, we ensure the kernel MSR:DE is appropriately cleared too
 485          * to avoid spurrious single step exceptions in the kernel.
 486          *
 487          * This will have to change to merge with the ppc32 code at some point,
 488          * but I don't like much what ppc32 is doing today so there's some
 489          * thinking needed there
 490          */
 491         if ((new_thread->dbcr0 | old_thread->dbcr0) & DBCR0_IDM) {
 492                 u32 dbcr0;
 493
 494                 mtmsr(mfmsr() & ~MSR_DE);
 495                 isync();
 496                 dbcr0 = mfspr(SPRN_DBCR0);
 497                 dbcr0 = (dbcr0 & DBCR0_EDM) | new_thread->dbcr0;
 498                 mtspr(SPRN_DBCR0, dbcr0);
 499         }
 500 #endif /* CONFIG_PPC64_BOOK3E */
 501
 502 #ifdef CONFIG_PPC64
 503         /*
 504          * Collect processor utilization data per process
 505          */
 506         if (firmware_has_feature(FW_FEATURE_SPLPAR)) {
 507                 struct cpu_usage *cu = &__get_cpu_var(cpu_usage_array);
 508                 long unsigned start_tb, current_tb;
 509                 start_tb = old_thread->start_tb;
 510                 cu->current_tb = current_tb = mfspr(SPRN_PURR);
 511                 old_thread->accum_tb += (current_tb - start_tb);
 512                 new_thread->start_tb = current_tb;
 513         }
 514 #endif
 515
 516         local_irq_save(flags);
 517
 518         account_system_vtime(current);
 519         account_process_vtime(current);
 520         calculate_steal_time();
 521
 522         /*
 523          * We can't take a PMU exception inside _switch() since there is a
 524          * window where the kernel stack SLB and the kernel stack are out
 525          * of sync. Hard disable here.
 526          */
 527         hard_irq_disable();
 528         last = _switch(old_thread, new_thread);
 529
 530         local_irq_restore(flags);
 531
 532         return last;
 533 }
 534
 535 static int instructions_to_print = 16;
 536
 537 static void show_instructions(struct pt_regs *regs)
 538 {
 539         int i;
 540         unsigned long pc = regs->nip - (instructions_to_print * 3 / 4 *
 541                         sizeof(int));
 542
 543         printk("Instruction dump:");
 544
 545         for (i = 0; i < instructions_to_print; i++) {
 546                 int instr;
 547
 548                 if (!(i % 8))
 549                         printk("\n");
 550
 551 #if !defined(CONFIG_BOOKE)
 552                 /* If executing with the IMMU off, adjust pc rather
 553                  * than print XXXXXXXX.
 554                  */
 555                 if (!(regs->msr & MSR_IR))
 556                         pc = (unsigned long)phys_to_virt(pc);
 557 #endif
 558
 559                 /* We use __get_user here *only* to avoid an OOPS on a
 560                  * bad address because the pc *should* only be a
 561                  * kernel address.
 562                  */
 563                 if (!__kernel_text_address(pc) ||
 564                      __get_user(instr, (unsigned int __user *)pc)) {
 565                         printk("XXXXXXXX ");
 566                 } else {
 567                         if (regs->nip == pc)
 568                                 printk("<%08x> ", instr);
 569                         else
 570                                 printk("%08x ", instr);
 571                 }
 572
 573                 pc += sizeof(int);
 574         }
 575
 576         printk("\n");
 577 }
 578
 579 static struct regbit {
 580         unsigned long bit;
 581         const char *name;
 582 } msr_bits[] = {
 583         {MSR_EE,        "EE"},
 584         {MSR_PR,        "PR"},
 585         {MSR_FP,        "FP"},
 586         {MSR_VEC,       "VEC"},
 587         {MSR_VSX,       "VSX"},
 588         {MSR_ME,        "ME"},
 589         {MSR_CE,        "CE"},
 590         {MSR_DE,        "DE"},
 591         {MSR_IR,        "IR"},
 592         {MSR_DR,        "DR"},
 593         {0,             NULL}
 594 };
 595
 596 static void printbits(unsigned long val, struct regbit *bits)
 597 {
 598         const char *sep = "";
 599
 600         printk("<");
 601         for (; bits->bit; ++bits)
 602                 if (val & bits->bit) {
 603                         printk("%s%s", sep, bits->name);
 604                         sep = ",";
 605                 }
 606         printk(">");
 607 }
 608
 609 #ifdef CONFIG_PPC64
 610 #define REG             "%016lx"
 611 #define REGS_PER_LINE   4
 612 #define LAST_VOLATILE   13
 613 #else
 614 #define REG             "%08lx"
 615 #define REGS_PER_LINE   8
 616 #define LAST_VOLATILE   12
 617 #endif
 618
 619 void show_regs(struct pt_regs * regs)
 620 {
 621         int i, trap;
 622
 623         printk("NIP: "REG" LR: "REG" CTR: "REG"\n",
 624                regs->nip, regs->link, regs->ctr);
 625         printk("REGS: %p TRAP: %04lx   %s  (%s)\n",
 626                regs, regs->trap, print_tainted(), init_utsname()->release);
 627         printk("MSR: "REG" ", regs->msr);
 628         printbits(regs->msr, msr_bits);
 629         printk("  CR: %08lx  XER: %08lx\n", regs->ccr, regs->xer);
 630         trap = TRAP(regs);
 631         if (trap == 0x300 || trap == 0x600)
 632 #ifdef CONFIG_PPC_ADV_DEBUG_REGS
 633                 printk("DEAR: "REG", ESR: "REG"\n", regs->dar, regs->dsisr);
 634 #else
 635                 printk("DAR: "REG", DSISR: "REG"\n", regs->dar, regs->dsisr);
 636 #endif
 637         printk("TASK = %p[%d] '%s' THREAD: %p",
 638                current, task_pid_nr(current), current->comm, task_thread_info(current));
 639
 640 #ifdef CONFIG_SMP
 641         printk(" CPU: %d", raw_smp_processor_id());
 642 #endif /* CONFIG_SMP */
 643
 644         for (i = 0;  i < 32;  i++) {
 645                 if ((i % REGS_PER_LINE) == 0)
 646                         printk("\nGPR%02d: ", i);
 647                 printk(REG " ", regs->gpr[i]);
 648                 if (i == LAST_VOLATILE && !FULL_REGS(regs))
 649                         break;
 650         }
 651         printk("\n");
 652 #ifdef CONFIG_KALLSYMS
 653         /*
 654          * Lookup NIP late so we have the best change of getting the
 655          * above info out without failing
 656          */
 657         printk("NIP ["REG"] %pS\n", regs->nip, (void *)regs->nip);
 658         printk("LR ["REG"] %pS\n", regs->link, (void *)regs->link);
 659 #endif
 660         show_stack(current, (unsigned long *) regs->gpr[1]);
 661         if (!user_mode(regs))
 662                 show_instructions(regs);
 663 }
 664
 665 void exit_thread(void)
 666 {
 667         discard_lazy_cpu_state();
 668 }
 669
 670 void flush_thread(void)
 671 {
 672         discard_lazy_cpu_state();
 673
 674 #ifdef CONFIG_HAVE_HW_BREAKPOINTS
 675         flush_ptrace_hw_breakpoint(current);
 676 #else /* CONFIG_HAVE_HW_BREAKPOINTS */
 677         set_debug_reg_defaults(&current->thread);
 678 #endif /* CONFIG_HAVE_HW_BREAKPOINTS */
 679 }
 680
 681 void
 682 release_thread(struct task_struct *t)
 683 {
 684 }
 685
 686 /*
 687  * This gets called before we allocate a new thread and copy
 688  * the current task into it.
 689  */
 690 void prepare_to_copy(struct task_struct *tsk)
 691 {
 692         flush_fp_to_thread(current);
 693         flush_altivec_to_thread(current);
 694         flush_vsx_to_thread(current);
 695         flush_spe_to_thread(current);
 696 #ifdef CONFIG_HAVE_HW_BREAKPOINT
 697         flush_ptrace_hw_breakpoint(tsk);
 698 #endif /* CONFIG_HAVE_HW_BREAKPOINT */
 699 }
 700
 701 /*
 702  * Copy a thread..
 703  */
 704 int copy_thread(unsigned long clone_flags, unsigned long usp,
 705                 unsigned long unused, struct task_struct *p,
 706                 struct pt_regs *regs)
 707 {
 708         struct pt_regs *childregs, *kregs;
 709         extern void ret_from_fork(void);
 710         unsigned long sp = (unsigned long)task_stack_page(p) + THREAD_SIZE;
 711
 712         CHECK_FULL_REGS(regs);
 713         /* Copy registers */
 714         sp -= sizeof(struct pt_regs);
 715         childregs = (struct pt_regs *) sp;
 716         *childregs = *regs;
 717         if ((childregs->msr & MSR_PR) == 0) {
 718                 /* for kernel thread, set `current' and stackptr in new task */
 719                 childregs->gpr[1] = sp + sizeof(struct pt_regs);
 720 #ifdef CONFIG_PPC32
 721                 childregs->gpr[2] = (unsigned long) p;
 722 #else
 723                 clear_tsk_thread_flag(p, TIF_32BIT);
 724 #endif
 725                 p->thread.regs = NULL;  /* no user register state */
 726         } else {
 727                 childregs->gpr[1] = usp;
 728                 p->thread.regs = childregs;
 729                 if (clone_flags & CLONE_SETTLS) {
 730 #ifdef CONFIG_PPC64
 731                         if (!test_thread_flag(TIF_32BIT))
 732                                 childregs->gpr[13] = childregs->gpr[6];
 733                         else
 734 #endif
 735                                 childregs->gpr[2] = childregs->gpr[6];
 736                 }
 737         }
 738         childregs->gpr[3] = 0;  /* Result from fork() */
 739         sp -= STACK_FRAME_OVERHEAD;
 740
 741         /*
 742          * The way this works is that at some point in the future
 743          * some task will call _switch to switch to the new task.
 744          * That will pop off the stack frame created below and start
 745          * the new task running at ret_from_fork.  The new task will
 746          * do some house keeping and then return from the fork or clone
 747          * system call, using the stack frame created above.
 748          */
 749         sp -= sizeof(struct pt_regs);
 750         kregs = (struct pt_regs *) sp;
 751         sp -= STACK_FRAME_OVERHEAD;
 752         p->thread.ksp = sp;
 753         p->thread.ksp_limit = (unsigned long)task_stack_page(p) +
 754                                 _ALIGN_UP(sizeof(struct thread_info), 16);
 755
 756 #ifdef CONFIG_PPC_STD_MMU_64
 757         if (cpu_has_feature(CPU_FTR_SLB)) {
 758                 unsigned long sp_vsid;
 759                 unsigned long llp = mmu_psize_defs[mmu_linear_psize].sllp;
 760
 761                 if (cpu_has_feature(CPU_FTR_1T_SEGMENT))
 762                         sp_vsid = get_kernel_vsid(sp, MMU_SEGSIZE_1T)
 763                                 << SLB_VSID_SHIFT_1T;
 764                 else
 765                         sp_vsid = get_kernel_vsid(sp, MMU_SEGSIZE_256M)
 766                                 << SLB_VSID_SHIFT;
 767                 sp_vsid |= SLB_VSID_KERNEL | llp;
 768                 p->thread.ksp_vsid = sp_vsid;
 769         }
 770 #endif /* CONFIG_PPC_STD_MMU_64 */
 771
 772         /*
 773          * The PPC64 ABI makes use of a TOC to contain function
 774          * pointers.  The function (ret_from_except) is actually a pointer
 775          * to the TOC entry.  The first entry is a pointer to the actual
 776          * function.
 777          */
 778 #ifdef CONFIG_PPC64
 779         kregs->nip = *((unsigned long *)ret_from_fork);
 780 #else
 781         kregs->nip = (unsigned long)ret_from_fork;
 782 #endif
 783
 784         return 0;
 785 }
 786
 787 /*
 788  * Set up a thread for executing a new program
 789  */
 790 void start_thread(struct pt_regs *regs, unsigned long start, unsigned long sp)
 791 {
 792 #ifdef CONFIG_PPC64
 793         unsigned long load_addr = regs->gpr[2]; /* saved by ELF_PLAT_INIT */
 794 #endif
 795
 796         set_fs(USER_DS);
 797
 798         /*
 799          * If we exec out of a kernel thread then thread.regs will not be
 800          * set.  Do it now.
 801          */
 802         if (!current->thread.regs) {
 803                 struct pt_regs *regs = task_stack_page(current) + THREAD_SIZE;
 804                 current->thread.regs = regs - 1;
 805         }
 806
 807         memset(regs->gpr, 0, sizeof(regs->gpr));
 808         regs->ctr = 0;
 809         regs->link = 0;
 810         regs->xer = 0;
 811         regs->ccr = 0;
 812         regs->gpr[1] = sp;
 813
 814         /*
 815          * We have just cleared all the nonvolatile GPRs, so make
 816          * FULL_REGS(regs) return true.  This is necessary to allow
 817          * ptrace to examine the thread immediately after exec.
 818          */
 819         regs->trap &= ~1UL;
 820
 821 #ifdef CONFIG_PPC32
 822         regs->mq = 0;
 823         regs->nip = start;
 824         regs->msr = MSR_USER;
 825 #else
 826         if (!test_thread_flag(TIF_32BIT)) {
 827                 unsigned long entry, toc;
 828
 829                 /* start is a relocated pointer to the function descriptor for
 830                  * the elf _start routine.  The first entry in the function
 831                  * descriptor is the entry address of _start and the second
 832                  * entry is the TOC value we need to use.
 833                  */
 834                 __get_user(entry, (unsigned long __user *)start);
 835                 __get_user(toc, (unsigned long __user *)start+1);
 836
 837                 /* Check whether the e_entry function descriptor entries
 838                  * need to be relocated before we can use them.
 839                  */
 840                 if (load_addr != 0) {
 841                         entry += load_addr;
 842                         toc   += load_addr;
 843                 }
 844                 regs->nip = entry;
 845                 regs->gpr[2] = toc;
 846                 regs->msr = MSR_USER64;
 847         } else {
 848                 regs->nip = start;
 849                 regs->gpr[2] = 0;
 850                 regs->msr = MSR_USER32;
 851         }
 852 #endif
 853
 854         discard_lazy_cpu_state();
 855 #ifdef CONFIG_VSX
 856         current->thread.used_vsr = 0;
 857 #endif
 858         memset(current->thread.fpr, 0, sizeof(current->thread.fpr));
 859         current->thread.fpscr.val = 0;
 860 #ifdef CONFIG_ALTIVEC
 861         memset(current->thread.vr, 0, sizeof(current->thread.vr));
 862         memset(&current->thread.vscr, 0, sizeof(current->thread.vscr));
 863         current->thread.vscr.u[3] = 0x00010000; /* Java mode disabled */
 864         current->thread.vrsave = 0;
 865         current->thread.used_vr = 0;
 866 #endif /* CONFIG_ALTIVEC */
 867 #ifdef CONFIG_SPE
 868         memset(current->thread.evr, 0, sizeof(current->thread.evr));
 869         current->thread.acc = 0;
 870         current->thread.spefscr = 0;
 871         current->thread.used_spe = 0;
 872 #endif /* CONFIG_SPE */
 873 }
 874
 875 #define PR_FP_ALL_EXCEPT (PR_FP_EXC_DIV | PR_FP_EXC_OVF | PR_FP_EXC_UND \
 876                 | PR_FP_EXC_RES | PR_FP_EXC_INV)
 877
 878 int set_fpexc_mode(struct task_struct *tsk, unsigned int val)
 879 {
 880         struct pt_regs *regs = tsk->thread.regs;
 881
 882         /* This is a bit hairy.  If we are an SPE enabled  processor
 883          * (have embedded fp) we store the IEEE exception enable flags in
 884          * fpexc_mode.  fpexc_mode is also used for setting FP exception
 885          * mode (asyn, precise, disabled) for 'Classic' FP. */
 886         if (val & PR_FP_EXC_SW_ENABLE) {
 887 #ifdef CONFIG_SPE
 888                 if (cpu_has_feature(CPU_FTR_SPE)) {
 889                         tsk->thread.fpexc_mode = val &
 890                                 (PR_FP_EXC_SW_ENABLE | PR_FP_ALL_EXCEPT);
 891                         return 0;
 892                 } else {
 893                         return -EINVAL;
 894                 }
 895 #else
 896                 return -EINVAL;
 897 #endif
 898         }
 899
 900         /* on a CONFIG_SPE this does not hurt us.  The bits that
 901          * __pack_fe01 use do not overlap with bits used for
 902          * PR_FP_EXC_SW_ENABLE.  Additionally, the MSR[FE0,FE1] bits
 903          * on CONFIG_SPE implementations are reserved so writing to
 904          * them does not change anything */
 905         if (val > PR_FP_EXC_PRECISE)
 906                 return -EINVAL;
 907         tsk->thread.fpexc_mode = __pack_fe01(val);
 908         if (regs != NULL && (regs->msr & MSR_FP) != 0)
 909                 regs->msr = (regs->msr & ~(MSR_FE0|MSR_FE1))
 910                         | tsk->thread.fpexc_mode;
 911         return 0;
 912 }
 913
 914 int get_fpexc_mode(struct task_struct *tsk, unsigned long adr)
 915 {
 916         unsigned int val;
 917
 918         if (tsk->thread.fpexc_mode & PR_FP_EXC_SW_ENABLE)
 919 #ifdef CONFIG_SPE
 920                 if (cpu_has_feature(CPU_FTR_SPE))
 921                         val = tsk->thread.fpexc_mode;
 922                 else
 923                         return -EINVAL;
 924 #else
 925                 return -EINVAL;
 926 #endif
 927         else
 928                 val = __unpack_fe01(tsk->thread.fpexc_mode);
 929         return put_user(val, (unsigned int __user *) adr);
 930 }
 931
 932 int set_endian(struct task_struct *tsk, unsigned int val)
 933 {
 934         struct pt_regs *regs = tsk->thread.regs;
 935
 936         if ((val == PR_ENDIAN_LITTLE && !cpu_has_feature(CPU_FTR_REAL_LE)) ||
 937             (val == PR_ENDIAN_PPC_LITTLE && !cpu_has_feature(CPU_FTR_PPC_LE)))
 938                 return -EINVAL;
 939
 940         if (regs == NULL)
 941                 return -EINVAL;
 942
 943         if (val == PR_ENDIAN_BIG)
 944                 regs->msr &= ~MSR_LE;
 945         else if (val == PR_ENDIAN_LITTLE || val == PR_ENDIAN_PPC_LITTLE)
 946                 regs->msr |= MSR_LE;
 947         else
 948                 return -EINVAL;
 949
 950         return 0;
 951 }
 952
 953 int get_endian(struct task_struct *tsk, unsigned long adr)
 954 {
 955         struct pt_regs *regs = tsk->thread.regs;
 956         unsigned int val;
 957
 958         if (!cpu_has_feature(CPU_FTR_PPC_LE) &&
 959             !cpu_has_feature(CPU_FTR_REAL_LE))
 960                 return -EINVAL;
 961
 962         if (regs == NULL)
 963                 return -EINVAL;
 964
 965         if (regs->msr & MSR_LE) {
 966                 if (cpu_has_feature(CPU_FTR_REAL_LE))
 967                         val = PR_ENDIAN_LITTLE;
 968                 else
 969                         val = PR_ENDIAN_PPC_LITTLE;
 970         } else
 971                 val = PR_ENDIAN_BIG;
 972
 973         return put_user(val, (unsigned int __user *)adr);
 974 }
 975
 976 int set_unalign_ctl(struct task_struct *tsk, unsigned int val)
 977 {
 978         tsk->thread.align_ctl = val;
 979         return 0;
 980 }
 981
 982 int get_unalign_ctl(struct task_struct *tsk, unsigned long adr)
 983 {
 984         return put_user(tsk->thread.align_ctl, (unsigned int __user *)adr);
 985 }
 986
 987 #define TRUNC_PTR(x)    ((typeof(x))(((unsigned long)(x)) & 0xffffffff))
 988
 989 int sys_clone(unsigned long clone_flags, unsigned long usp,
 990               int __user *parent_tidp, void __user *child_threadptr,
 991               int __user *child_tidp, int p6,
 992               struct pt_regs *regs)
 993 {
 994         CHECK_FULL_REGS(regs);
 995         if (usp == 0)
 996                 usp = regs->gpr[1];     /* stack pointer for child */
 997 #ifdef CONFIG_PPC64
 998         if (test_thread_flag(TIF_32BIT)) {
 999                 parent_tidp = TRUNC_PTR(parent_tidp);
1000                 child_tidp = TRUNC_PTR(child_tidp);
1001         }
1002 #endif
1003         return do_fork(clone_flags, usp, regs, 0, parent_tidp, child_tidp);
1004 }
1005
1006 int sys_fork(unsigned long p1, unsigned long p2, unsigned long p3,
1007              unsigned long p4, unsigned long p5, unsigned long p6,
1008              struct pt_regs *regs)
1009 {
1010         CHECK_FULL_REGS(regs);
1011         return do_fork(SIGCHLD, regs->gpr[1], regs, 0, NULL, NULL);
1012 }
1013
1014 int sys_vfork(unsigned long p1, unsigned long p2, unsigned long p3,
1015               unsigned long p4, unsigned long p5, unsigned long p6,
1016               struct pt_regs *regs)
1017 {
1018         CHECK_FULL_REGS(regs);
1019         return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, regs->gpr[1],
1020                         regs, 0, NULL, NULL);
1021 }
1022
1023 int sys_execve(unsigned long a0, unsigned long a1, unsigned long a2,
1024                unsigned long a3, unsigned long a4, unsigned long a5,
1025                struct pt_regs *regs)
1026 {
1027         int error;
1028         char *filename;
1029
1030         filename = getname((char __user *) a0);
1031         error = PTR_ERR(filename);
1032         if (IS_ERR(filename))
1033                 goto out;
1034         flush_fp_to_thread(current);
1035         flush_altivec_to_thread(current);
1036         flush_spe_to_thread(current);
1037         error = do_execve(filename, (char __user * __user *) a1,
1038                           (char __user * __user *) a2, regs);
1039         putname(filename);
1040 out:
1041         return error;
1042 }
1043
1044 static inline int valid_irq_stack(unsigned long sp, struct task_struct *p,
1045                                   unsigned long nbytes)
1046 {
1047         unsigned long stack_page;
1048         unsigned long cpu = task_cpu(p);
1049
1050         /*
1051          * Avoid crashing if the stack has overflowed and corrupted
1052          * task_cpu(p), which is in the thread_info struct.
1053          */
1054         if (cpu < NR_CPUS && cpu_possible(cpu)) {
1055                 stack_page = (unsigned long) hardirq_ctx[cpu];
1056                 if (sp >= stack_page + sizeof(struct thread_struct)
1057                     && sp <= stack_page + THREAD_SIZE - nbytes)
1058                         return 1;
1059
1060                 stack_page = (unsigned long) softirq_ctx[cpu];
1061                 if (sp >= stack_page + sizeof(struct thread_struct)
1062                     && sp <= stack_page + THREAD_SIZE - nbytes)
1063                         return 1;
1064         }
1065         return 0;
1066 }
1067
1068 int validate_sp(unsigned long sp, struct task_struct *p,
1069                        unsigned long nbytes)
1070 {
1071         unsigned long stack_page = (unsigned long)task_stack_page(p);
1072
1073         if (sp >= stack_page + sizeof(struct thread_struct)
1074             && sp <= stack_page + THREAD_SIZE - nbytes)
1075                 return 1;
1076
1077         return valid_irq_stack(sp, p, nbytes);
1078 }
1079
1080 EXPORT_SYMBOL(validate_sp);
1081
1082 unsigned long get_wchan(struct task_struct *p)
1083 {
1084         unsigned long ip, sp;
1085         int count = 0;
1086
1087         if (!p || p == current || p->state == TASK_RUNNING)
1088                 return 0;
1089
1090         sp = p->thread.ksp;
1091         if (!validate_sp(sp, p, STACK_FRAME_OVERHEAD))
1092                 return 0;
1093
1094         do {
1095                 sp = *(unsigned long *)sp;
1096                 if (!validate_sp(sp, p, STACK_FRAME_OVERHEAD))
1097                         return 0;
1098                 if (count > 0) {
1099                         ip = ((unsigned long *)sp)[STACK_FRAME_LR_SAVE];
1100                         if (!in_sched_functions(ip))
1101                                 return ip;
1102                 }
1103         } while (count++ < 16);
1104         return 0;
1105 }
1106
1107 static int kstack_depth_to_print = CONFIG_PRINT_STACK_DEPTH;
1108
1109 void show_stack(struct task_struct *tsk, unsigned long *stack)
1110 {
1111         unsigned long sp, ip, lr, newsp;
1112         int count = 0;
1113         int firstframe = 1;
1114 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
1115         int curr_frame = current->curr_ret_stack;
1116         extern void return_to_handler(void);
1117         unsigned long rth = (unsigned long)return_to_handler;
1118         unsigned long mrth = -1;
1119 #ifdef CONFIG_PPC64
1120         extern void mod_return_to_handler(void);
1121         rth = *(unsigned long *)rth;
1122         mrth = (unsigned long)mod_return_to_handler;
1123         mrth = *(unsigned long *)mrth;
1124 #endif
1125 #endif
1126
1127         sp = (unsigned long) stack;
1128         if (tsk == NULL)
1129                 tsk = current;
1130         if (sp == 0) {
1131                 if (tsk == current)
1132                         asm("mr %0,1" : "=r" (sp));
1133                 else
1134                         sp = tsk->thread.ksp;
1135         }
1136
1137         lr = 0;
1138         printk("Call Trace:\n");
1139         do {
1140                 if (!validate_sp(sp, tsk, STACK_FRAME_OVERHEAD))
1141                         return;
1142
1143                 stack = (unsigned long *) sp;
1144                 newsp = stack[0];
1145                 ip = stack[STACK_FRAME_LR_SAVE];
1146                 if (!firstframe || ip != lr) {
1147                         printk("["REG"] ["REG"] %pS", sp, ip, (void *)ip);
1148 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
1149                         if ((ip == rth || ip == mrth) && curr_frame >= 0) {
1150                                 printk(" (%pS)",
1151                                        (void *)current->ret_stack[curr_frame].ret);
1152                                 curr_frame--;
1153                         }
1154 #endif
1155                         if (firstframe)
1156                                 printk(" (unreliable)");
1157                         printk("\n");
1158                 }
1159                 firstframe = 0;
1160
1161                 /*
1162                  * See if this is an exception frame.
1163                  * We look for the "regshere" marker in the current frame.
1164                  */
1165                 if (validate_sp(sp, tsk, STACK_INT_FRAME_SIZE)
1166                     && stack[STACK_FRAME_MARKER] == STACK_FRAME_REGS_MARKER) {
1167                         struct pt_regs *regs = (struct pt_regs *)
1168                                 (sp + STACK_FRAME_OVERHEAD);
1169                         lr = regs->link;
1170                         printk("--- Exception: %lx at %pS\n    LR = %pS\n",
1171                                regs->trap, (void *)regs->nip, (void *)lr);
1172                         firstframe = 1;
1173                 }
1174
1175                 sp = newsp;
1176         } while (count++ < kstack_depth_to_print);
1177 }
1178
1179 void dump_stack(void)
1180 {
1181         show_stack(current, NULL);
1182 }
1183 EXPORT_SYMBOL(dump_stack);
1184
1185 #ifdef CONFIG_PPC64
1186 void ppc64_runlatch_on(void)
1187 {
1188         unsigned long ctrl;
1189
1190         if (cpu_has_feature(CPU_FTR_CTRL) && !test_thread_flag(TIF_RUNLATCH)) {
1191                 HMT_medium();
1192
1193                 ctrl = mfspr(SPRN_CTRLF);
1194                 ctrl |= CTRL_RUNLATCH;
1195                 mtspr(SPRN_CTRLT, ctrl);
1196
1197                 set_thread_flag(TIF_RUNLATCH);
1198         }
1199 }
1200
1201 void ppc64_runlatch_off(void)
1202 {
1203         unsigned long ctrl;
1204
1205         if (cpu_has_feature(CPU_FTR_CTRL) && test_thread_flag(TIF_RUNLATCH)) {
1206                 HMT_medium();
1207
1208                 clear_thread_flag(TIF_RUNLATCH);
1209
1210                 ctrl = mfspr(SPRN_CTRLF);
1211                 ctrl &= ~CTRL_RUNLATCH;
1212                 mtspr(SPRN_CTRLT, ctrl);
1213         }
1214 }
1215 #endif
1216
1217 #if THREAD_SHIFT < PAGE_SHIFT
1218
1219 static struct kmem_cache *thread_info_cache;
1220
1221 struct thread_info *alloc_thread_info(struct task_struct *tsk)
1222 {
1223         struct thread_info *ti;
1224
1225         ti = kmem_cache_alloc(thread_info_cache, GFP_KERNEL);
1226         if (unlikely(ti == NULL))
1227                 return NULL;
1228 #ifdef CONFIG_DEBUG_STACK_USAGE
1229         memset(ti, 0, THREAD_SIZE);
1230 #endif
1231         return ti;
1232 }
1233
1234 void free_thread_info(struct thread_info *ti)
1235 {
1236         kmem_cache_free(thread_info_cache, ti);
1237 }
1238
1239 void thread_info_cache_init(void)
1240 {
1241         thread_info_cache = kmem_cache_create("thread_info", THREAD_SIZE,
1242                                               THREAD_SIZE, 0, NULL);
1243         BUG_ON(thread_info_cache == NULL);
1244 }
1245
1246 #endif /* THREAD_SHIFT < PAGE_SHIFT */
1247
1248 unsigned long arch_align_stack(unsigned long sp)
1249 {
1250         if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
1251                 sp -= get_random_int() & ~PAGE_MASK;
1252         return sp & ~0xf;
1253 }
1254
1255 static inline unsigned long brk_rnd(void)
1256 {
1257         unsigned long rnd = 0;
1258
1259         /* 8MB for 32bit, 1GB for 64bit */
1260         if (is_32bit_task())
1261                 rnd = (long)(get_random_int() % (1<<(23-PAGE_SHIFT)));
1262         else
1263                 rnd = (long)(get_random_int() % (1<<(30-PAGE_SHIFT)));
1264
1265         return rnd << PAGE_SHIFT;
1266 }
1267
1268 unsigned long arch_randomize_brk(struct mm_struct *mm)
1269 {
1270         unsigned long base = mm->brk;
1271         unsigned long ret;
1272
1273 #ifdef CONFIG_PPC_STD_MMU_64
1274         /*
1275          * If we are using 1TB segments and we are allowed to randomise
1276          * the heap, we can put it above 1TB so it is backed by a 1TB
1277          * segment. Otherwise the heap will be in the bottom 1TB
1278          * which always uses 256MB segments and this may result in a
1279          * performance penalty.
1280          */
1281         if (!is_32bit_task() && (mmu_highuser_ssize == MMU_SEGSIZE_1T))
1282                 base = max_t(unsigned long, mm->brk, 1UL << SID_SHIFT_1T);
1283 #endif
1284
1285         ret = PAGE_ALIGN(base + brk_rnd());
1286
1287         if (ret < mm->brk)
1288                 return mm->brk;
1289
1290         return ret;
1291 }
1292
1293 unsigned long randomize_et_dyn(unsigned long base)
1294 {
1295         unsigned long ret = PAGE_ALIGN(base + brk_rnd());
1296
1297         if (ret < base)
1298                 return base;
1299
1300         return ret;
1301 }