process_32.c revision fb26132b441e75d6ba9996efc29b42081aee0abd
1/* 2 * Copyright (C) 1995 Linus Torvalds 3 * 4 * Pentium III FXSR, SSE support 5 * Gareth Hughes <gareth@valinux.com>, May 2000 6 */ 7 8/* 9 * This file handles the architecture-dependent parts of process handling.. 10 */ 11 12#include <stdarg.h> 13 14#include <linux/cpu.h> 15#include <linux/errno.h> 16#include <linux/sched.h> 17#include <linux/fs.h> 18#include <linux/kernel.h> 19#include <linux/mm.h> 20#include <linux/elfcore.h> 21#include <linux/smp.h> 22#include <linux/stddef.h> 23#include <linux/slab.h> 24#include <linux/vmalloc.h> 25#include <linux/user.h> 26#include <linux/interrupt.h> 27#include <linux/utsname.h> 28#include <linux/delay.h> 29#include <linux/reboot.h> 30#include <linux/init.h> 31#include <linux/mc146818rtc.h> 32#include <linux/module.h> 33#include <linux/kallsyms.h> 34#include <linux/ptrace.h> 35#include <linux/random.h> 36#include <linux/personality.h> 37#include <linux/tick.h> 38#include <linux/percpu.h> 39#include <linux/prctl.h> 40 41#include <asm/uaccess.h> 42#include <asm/pgtable.h> 43#include <asm/system.h> 44#include <asm/io.h> 45#include <asm/ldt.h> 46#include <asm/processor.h> 47#include <asm/i387.h> 48#include <asm/desc.h> 49#ifdef CONFIG_MATH_EMULATION 50#include <asm/math_emu.h> 51#endif 52 53#include <linux/err.h> 54 55#include <asm/tlbflush.h> 56#include <asm/cpu.h> 57#include <asm/kdebug.h> 58#include <asm/syscalls.h> 59#include <asm/smp.h> 60 61asmlinkage void ret_from_fork(void) __asm__("ret_from_fork"); 62 63DEFINE_PER_CPU(struct task_struct *, current_task) = &init_task; 64EXPORT_PER_CPU_SYMBOL(current_task); 65 66DEFINE_PER_CPU(int, cpu_number); 67EXPORT_PER_CPU_SYMBOL(cpu_number); 68 69/* 70 * Return saved PC of a blocked thread. 71 */ 72unsigned long thread_saved_pc(struct task_struct *tsk) 73{ 74 return ((unsigned long *)tsk->thread.sp)[3]; 75} 76 77#ifdef CONFIG_HOTPLUG_CPU 78#include <asm/nmi.h> 79 80static void cpu_exit_clear(void) 81{ 82 int cpu = raw_smp_processor_id(); 83 84 idle_task_exit(); 85 86 cpu_uninit(); 87 irq_ctx_exit(cpu); 88 89 cpu_clear(cpu, cpu_callout_map); 90 cpu_clear(cpu, cpu_callin_map); 91 92 numa_remove_cpu(cpu); 93} 94 95/* We don't actually take CPU down, just spin without interrupts. */ 96static inline void play_dead(void) 97{ 98 /* This must be done before dead CPU ack */ 99 cpu_exit_clear(); 100 wbinvd(); 101 mb(); 102 /* Ack it */ 103 __get_cpu_var(cpu_state) = CPU_DEAD; 104 105 /* 106 * With physical CPU hotplug, we should halt the cpu 107 */ 108 local_irq_disable(); 109 while (1) 110 halt(); 111} 112#else 113static inline void play_dead(void) 114{ 115 BUG(); 116} 117#endif /* CONFIG_HOTPLUG_CPU */ 118 119/* 120 * The idle thread. There's no useful work to be 121 * done, so just try to conserve power and have a 122 * low exit latency (ie sit in a loop waiting for 123 * somebody to say that they'd like to reschedule) 124 */ 125void cpu_idle(void) 126{ 127 int cpu = smp_processor_id(); 128 129 current_thread_info()->status |= TS_POLLING; 130 131 /* endless idle loop with no priority at all */ 132 while (1) { 133 tick_nohz_stop_sched_tick(); 134 while (!need_resched()) { 135 136 check_pgt_cache(); 137 rmb(); 138 139 if (rcu_pending(cpu)) 140 rcu_check_callbacks(cpu, 0); 141 142 if (cpu_is_offline(cpu)) 143 play_dead(); 144 145 local_irq_disable(); 146 __get_cpu_var(irq_stat).idle_timestamp = jiffies; 147 /* Don't trace irqs off for idle */ 148 stop_critical_timings(); 149 pm_idle(); 150 start_critical_timings(); 151 } 152 tick_nohz_restart_sched_tick(); 153 preempt_enable_no_resched(); 154 schedule(); 155 preempt_disable(); 156 } 157} 158 159void __show_registers(struct pt_regs *regs, int all) 160{ 161 unsigned long cr0 = 0L, cr2 = 0L, cr3 = 0L, cr4 = 0L; 162 unsigned long d0, d1, d2, d3, d6, d7; 163 unsigned long sp; 164 unsigned short ss, gs; 165 166 if (user_mode_vm(regs)) { 167 sp = regs->sp; 168 ss = regs->ss & 0xffff; 169 savesegment(gs, gs); 170 } else { 171 sp = (unsigned long) (®s->sp); 172 savesegment(ss, ss); 173 savesegment(gs, gs); 174 } 175 176 printk("\n"); 177 printk("Pid: %d, comm: %s %s (%s %.*s)\n", 178 task_pid_nr(current), current->comm, 179 print_tainted(), init_utsname()->release, 180 (int)strcspn(init_utsname()->version, " "), 181 init_utsname()->version); 182 183 printk("EIP: %04x:[<%08lx>] EFLAGS: %08lx CPU: %d\n", 184 (u16)regs->cs, regs->ip, regs->flags, 185 smp_processor_id()); 186 print_symbol("EIP is at %s\n", regs->ip); 187 188 printk("EAX: %08lx EBX: %08lx ECX: %08lx EDX: %08lx\n", 189 regs->ax, regs->bx, regs->cx, regs->dx); 190 printk("ESI: %08lx EDI: %08lx EBP: %08lx ESP: %08lx\n", 191 regs->si, regs->di, regs->bp, sp); 192 printk(" DS: %04x ES: %04x FS: %04x GS: %04x SS: %04x\n", 193 (u16)regs->ds, (u16)regs->es, (u16)regs->fs, gs, ss); 194 195 if (!all) 196 return; 197 198 cr0 = read_cr0(); 199 cr2 = read_cr2(); 200 cr3 = read_cr3(); 201 cr4 = read_cr4_safe(); 202 printk("CR0: %08lx CR2: %08lx CR3: %08lx CR4: %08lx\n", 203 cr0, cr2, cr3, cr4); 204 205 get_debugreg(d0, 0); 206 get_debugreg(d1, 1); 207 get_debugreg(d2, 2); 208 get_debugreg(d3, 3); 209 printk("DR0: %08lx DR1: %08lx DR2: %08lx DR3: %08lx\n", 210 d0, d1, d2, d3); 211 212 get_debugreg(d6, 6); 213 get_debugreg(d7, 7); 214 printk("DR6: %08lx DR7: %08lx\n", 215 d6, d7); 216} 217 218void show_regs(struct pt_regs *regs) 219{ 220 __show_registers(regs, 1); 221 show_trace(NULL, regs, ®s->sp, regs->bp); 222} 223 224/* 225 * This gets run with %bx containing the 226 * function to call, and %dx containing 227 * the "args". 228 */ 229extern void kernel_thread_helper(void); 230 231/* 232 * Create a kernel thread 233 */ 234int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags) 235{ 236 struct pt_regs regs; 237 238 memset(®s, 0, sizeof(regs)); 239 240 regs.bx = (unsigned long) fn; 241 regs.dx = (unsigned long) arg; 242 243 regs.ds = __USER_DS; 244 regs.es = __USER_DS; 245 regs.fs = __KERNEL_PERCPU; 246 regs.orig_ax = -1; 247 regs.ip = (unsigned long) kernel_thread_helper; 248 regs.cs = __KERNEL_CS | get_kernel_rpl(); 249 regs.flags = X86_EFLAGS_IF | X86_EFLAGS_SF | X86_EFLAGS_PF | 0x2; 250 251 /* Ok, create the new process.. */ 252 return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, ®s, 0, NULL, NULL); 253} 254EXPORT_SYMBOL(kernel_thread); 255 256/* 257 * Free current thread data structures etc.. 258 */ 259void exit_thread(void) 260{ 261 /* The process may have allocated an io port bitmap... nuke it. */ 262 if (unlikely(test_thread_flag(TIF_IO_BITMAP))) { 263 struct task_struct *tsk = current; 264 struct thread_struct *t = &tsk->thread; 265 int cpu = get_cpu(); 266 struct tss_struct *tss = &per_cpu(init_tss, cpu); 267 268 kfree(t->io_bitmap_ptr); 269 t->io_bitmap_ptr = NULL; 270 clear_thread_flag(TIF_IO_BITMAP); 271 /* 272 * Careful, clear this in the TSS too: 273 */ 274 memset(tss->io_bitmap, 0xff, tss->io_bitmap_max); 275 t->io_bitmap_max = 0; 276 tss->io_bitmap_owner = NULL; 277 tss->io_bitmap_max = 0; 278 tss->x86_tss.io_bitmap_base = INVALID_IO_BITMAP_OFFSET; 279 put_cpu(); 280 } 281} 282 283void flush_thread(void) 284{ 285 struct task_struct *tsk = current; 286 287 tsk->thread.debugreg0 = 0; 288 tsk->thread.debugreg1 = 0; 289 tsk->thread.debugreg2 = 0; 290 tsk->thread.debugreg3 = 0; 291 tsk->thread.debugreg6 = 0; 292 tsk->thread.debugreg7 = 0; 293 memset(tsk->thread.tls_array, 0, sizeof(tsk->thread.tls_array)); 294 clear_tsk_thread_flag(tsk, TIF_DEBUG); 295 /* 296 * Forget coprocessor state.. 297 */ 298 tsk->fpu_counter = 0; 299 clear_fpu(tsk); 300 clear_used_math(); 301} 302 303void release_thread(struct task_struct *dead_task) 304{ 305 BUG_ON(dead_task->mm); 306 release_vm86_irqs(dead_task); 307} 308 309/* 310 * This gets called before we allocate a new thread and copy 311 * the current task into it. 312 */ 313void prepare_to_copy(struct task_struct *tsk) 314{ 315 unlazy_fpu(tsk); 316} 317 318int copy_thread(int nr, unsigned long clone_flags, unsigned long sp, 319 unsigned long unused, 320 struct task_struct * p, struct pt_regs * regs) 321{ 322 struct pt_regs * childregs; 323 struct task_struct *tsk; 324 int err; 325 326 childregs = task_pt_regs(p); 327 *childregs = *regs; 328 childregs->ax = 0; 329 childregs->sp = sp; 330 331 p->thread.sp = (unsigned long) childregs; 332 p->thread.sp0 = (unsigned long) (childregs+1); 333 334 p->thread.ip = (unsigned long) ret_from_fork; 335 336 savesegment(gs, p->thread.gs); 337 338 tsk = current; 339 if (unlikely(test_tsk_thread_flag(tsk, TIF_IO_BITMAP))) { 340 p->thread.io_bitmap_ptr = kmemdup(tsk->thread.io_bitmap_ptr, 341 IO_BITMAP_BYTES, GFP_KERNEL); 342 if (!p->thread.io_bitmap_ptr) { 343 p->thread.io_bitmap_max = 0; 344 return -ENOMEM; 345 } 346 set_tsk_thread_flag(p, TIF_IO_BITMAP); 347 } 348 349 err = 0; 350 351 /* 352 * Set a new TLS for the child thread? 353 */ 354 if (clone_flags & CLONE_SETTLS) 355 err = do_set_thread_area(p, -1, 356 (struct user_desc __user *)childregs->si, 0); 357 358 if (err && p->thread.io_bitmap_ptr) { 359 kfree(p->thread.io_bitmap_ptr); 360 p->thread.io_bitmap_max = 0; 361 } 362 return err; 363} 364 365void 366start_thread(struct pt_regs *regs, unsigned long new_ip, unsigned long new_sp) 367{ 368 __asm__("movl %0, %%gs" :: "r"(0)); 369 regs->fs = 0; 370 set_fs(USER_DS); 371 regs->ds = __USER_DS; 372 regs->es = __USER_DS; 373 regs->ss = __USER_DS; 374 regs->cs = __USER_CS; 375 regs->ip = new_ip; 376 regs->sp = new_sp; 377 /* 378 * Free the old FP and other extended state 379 */ 380 free_thread_xstate(current); 381} 382EXPORT_SYMBOL_GPL(start_thread); 383 384static void hard_disable_TSC(void) 385{ 386 write_cr4(read_cr4() | X86_CR4_TSD); 387} 388 389void disable_TSC(void) 390{ 391 preempt_disable(); 392 if (!test_and_set_thread_flag(TIF_NOTSC)) 393 /* 394 * Must flip the CPU state synchronously with 395 * TIF_NOTSC in the current running context. 396 */ 397 hard_disable_TSC(); 398 preempt_enable(); 399} 400 401static void hard_enable_TSC(void) 402{ 403 write_cr4(read_cr4() & ~X86_CR4_TSD); 404} 405 406static void enable_TSC(void) 407{ 408 preempt_disable(); 409 if (test_and_clear_thread_flag(TIF_NOTSC)) 410 /* 411 * Must flip the CPU state synchronously with 412 * TIF_NOTSC in the current running context. 413 */ 414 hard_enable_TSC(); 415 preempt_enable(); 416} 417 418int get_tsc_mode(unsigned long adr) 419{ 420 unsigned int val; 421 422 if (test_thread_flag(TIF_NOTSC)) 423 val = PR_TSC_SIGSEGV; 424 else 425 val = PR_TSC_ENABLE; 426 427 return put_user(val, (unsigned int __user *)adr); 428} 429 430int set_tsc_mode(unsigned int val) 431{ 432 if (val == PR_TSC_SIGSEGV) 433 disable_TSC(); 434 else if (val == PR_TSC_ENABLE) 435 enable_TSC(); 436 else 437 return -EINVAL; 438 439 return 0; 440} 441 442static noinline void 443__switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p, 444 struct tss_struct *tss) 445{ 446 struct thread_struct *prev, *next; 447 unsigned long debugctl; 448 449 prev = &prev_p->thread; 450 next = &next_p->thread; 451 452 debugctl = prev->debugctlmsr; 453 if (next->ds_area_msr != prev->ds_area_msr) { 454 /* we clear debugctl to make sure DS 455 * is not in use when we change it */ 456 debugctl = 0; 457 update_debugctlmsr(0); 458 wrmsr(MSR_IA32_DS_AREA, next->ds_area_msr, 0); 459 } 460 461 if (next->debugctlmsr != debugctl) 462 update_debugctlmsr(next->debugctlmsr); 463 464 if (test_tsk_thread_flag(next_p, TIF_DEBUG)) { 465 set_debugreg(next->debugreg0, 0); 466 set_debugreg(next->debugreg1, 1); 467 set_debugreg(next->debugreg2, 2); 468 set_debugreg(next->debugreg3, 3); 469 /* no 4 and 5 */ 470 set_debugreg(next->debugreg6, 6); 471 set_debugreg(next->debugreg7, 7); 472 } 473 474 if (test_tsk_thread_flag(prev_p, TIF_NOTSC) ^ 475 test_tsk_thread_flag(next_p, TIF_NOTSC)) { 476 /* prev and next are different */ 477 if (test_tsk_thread_flag(next_p, TIF_NOTSC)) 478 hard_disable_TSC(); 479 else 480 hard_enable_TSC(); 481 } 482 483#ifdef X86_BTS 484 if (test_tsk_thread_flag(prev_p, TIF_BTS_TRACE_TS)) 485 ptrace_bts_take_timestamp(prev_p, BTS_TASK_DEPARTS); 486 487 if (test_tsk_thread_flag(next_p, TIF_BTS_TRACE_TS)) 488 ptrace_bts_take_timestamp(next_p, BTS_TASK_ARRIVES); 489#endif 490 491 492 if (!test_tsk_thread_flag(next_p, TIF_IO_BITMAP)) { 493 /* 494 * Disable the bitmap via an invalid offset. We still cache 495 * the previous bitmap owner and the IO bitmap contents: 496 */ 497 tss->x86_tss.io_bitmap_base = INVALID_IO_BITMAP_OFFSET; 498 return; 499 } 500 501 if (likely(next == tss->io_bitmap_owner)) { 502 /* 503 * Previous owner of the bitmap (hence the bitmap content) 504 * matches the next task, we dont have to do anything but 505 * to set a valid offset in the TSS: 506 */ 507 tss->x86_tss.io_bitmap_base = IO_BITMAP_OFFSET; 508 return; 509 } 510 /* 511 * Lazy TSS's I/O bitmap copy. We set an invalid offset here 512 * and we let the task to get a GPF in case an I/O instruction 513 * is performed. The handler of the GPF will verify that the 514 * faulting task has a valid I/O bitmap and, it true, does the 515 * real copy and restart the instruction. This will save us 516 * redundant copies when the currently switched task does not 517 * perform any I/O during its timeslice. 518 */ 519 tss->x86_tss.io_bitmap_base = INVALID_IO_BITMAP_OFFSET_LAZY; 520} 521 522/* 523 * switch_to(x,yn) should switch tasks from x to y. 524 * 525 * We fsave/fwait so that an exception goes off at the right time 526 * (as a call from the fsave or fwait in effect) rather than to 527 * the wrong process. Lazy FP saving no longer makes any sense 528 * with modern CPU's, and this simplifies a lot of things (SMP 529 * and UP become the same). 530 * 531 * NOTE! We used to use the x86 hardware context switching. The 532 * reason for not using it any more becomes apparent when you 533 * try to recover gracefully from saved state that is no longer 534 * valid (stale segment register values in particular). With the 535 * hardware task-switch, there is no way to fix up bad state in 536 * a reasonable manner. 537 * 538 * The fact that Intel documents the hardware task-switching to 539 * be slow is a fairly red herring - this code is not noticeably 540 * faster. However, there _is_ some room for improvement here, 541 * so the performance issues may eventually be a valid point. 542 * More important, however, is the fact that this allows us much 543 * more flexibility. 544 * 545 * The return value (in %ax) will be the "prev" task after 546 * the task-switch, and shows up in ret_from_fork in entry.S, 547 * for example. 548 */ 549struct task_struct * __switch_to(struct task_struct *prev_p, struct task_struct *next_p) 550{ 551 struct thread_struct *prev = &prev_p->thread, 552 *next = &next_p->thread; 553 int cpu = smp_processor_id(); 554 struct tss_struct *tss = &per_cpu(init_tss, cpu); 555 556 /* never put a printk in __switch_to... printk() calls wake_up*() indirectly */ 557 558 __unlazy_fpu(prev_p); 559 560 561 /* we're going to use this soon, after a few expensive things */ 562 if (next_p->fpu_counter > 5) 563 prefetch(next->xstate); 564 565 /* 566 * Reload esp0. 567 */ 568 load_sp0(tss, next); 569 570 /* 571 * Save away %gs. No need to save %fs, as it was saved on the 572 * stack on entry. No need to save %es and %ds, as those are 573 * always kernel segments while inside the kernel. Doing this 574 * before setting the new TLS descriptors avoids the situation 575 * where we temporarily have non-reloadable segments in %fs 576 * and %gs. This could be an issue if the NMI handler ever 577 * used %fs or %gs (it does not today), or if the kernel is 578 * running inside of a hypervisor layer. 579 */ 580 savesegment(gs, prev->gs); 581 582 /* 583 * Load the per-thread Thread-Local Storage descriptor. 584 */ 585 load_TLS(next, cpu); 586 587 /* 588 * Restore IOPL if needed. In normal use, the flags restore 589 * in the switch assembly will handle this. But if the kernel 590 * is running virtualized at a non-zero CPL, the popf will 591 * not restore flags, so it must be done in a separate step. 592 */ 593 if (get_kernel_rpl() && unlikely(prev->iopl != next->iopl)) 594 set_iopl_mask(next->iopl); 595 596 /* 597 * Now maybe handle debug registers and/or IO bitmaps 598 */ 599 if (unlikely(task_thread_info(prev_p)->flags & _TIF_WORK_CTXSW_PREV || 600 task_thread_info(next_p)->flags & _TIF_WORK_CTXSW_NEXT)) 601 __switch_to_xtra(prev_p, next_p, tss); 602 603 /* 604 * Leave lazy mode, flushing any hypercalls made here. 605 * This must be done before restoring TLS segments so 606 * the GDT and LDT are properly updated, and must be 607 * done before math_state_restore, so the TS bit is up 608 * to date. 609 */ 610 arch_leave_lazy_cpu_mode(); 611 612 /* If the task has used fpu the last 5 timeslices, just do a full 613 * restore of the math state immediately to avoid the trap; the 614 * chances of needing FPU soon are obviously high now 615 * 616 * tsk_used_math() checks prevent calling math_state_restore(), 617 * which can sleep in the case of !tsk_used_math() 618 */ 619 if (tsk_used_math(next_p) && next_p->fpu_counter > 5) 620 math_state_restore(); 621 622 /* 623 * Restore %gs if needed (which is common) 624 */ 625 if (prev->gs | next->gs) 626 loadsegment(gs, next->gs); 627 628 x86_write_percpu(current_task, next_p); 629 630 return prev_p; 631} 632 633asmlinkage int sys_fork(struct pt_regs regs) 634{ 635 return do_fork(SIGCHLD, regs.sp, ®s, 0, NULL, NULL); 636} 637 638asmlinkage int sys_clone(struct pt_regs regs) 639{ 640 unsigned long clone_flags; 641 unsigned long newsp; 642 int __user *parent_tidptr, *child_tidptr; 643 644 clone_flags = regs.bx; 645 newsp = regs.cx; 646 parent_tidptr = (int __user *)regs.dx; 647 child_tidptr = (int __user *)regs.di; 648 if (!newsp) 649 newsp = regs.sp; 650 return do_fork(clone_flags, newsp, ®s, 0, parent_tidptr, child_tidptr); 651} 652 653/* 654 * This is trivial, and on the face of it looks like it 655 * could equally well be done in user mode. 656 * 657 * Not so, for quite unobvious reasons - register pressure. 658 * In user mode vfork() cannot have a stack frame, and if 659 * done by calling the "clone()" system call directly, you 660 * do not have enough call-clobbered registers to hold all 661 * the information you need. 662 */ 663asmlinkage int sys_vfork(struct pt_regs regs) 664{ 665 return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, regs.sp, ®s, 0, NULL, NULL); 666} 667 668/* 669 * sys_execve() executes a new program. 670 */ 671asmlinkage int sys_execve(struct pt_regs regs) 672{ 673 int error; 674 char * filename; 675 676 filename = getname((char __user *) regs.bx); 677 error = PTR_ERR(filename); 678 if (IS_ERR(filename)) 679 goto out; 680 error = do_execve(filename, 681 (char __user * __user *) regs.cx, 682 (char __user * __user *) regs.dx, 683 ®s); 684 if (error == 0) { 685 /* Make sure we don't return using sysenter.. */ 686 set_thread_flag(TIF_IRET); 687 } 688 putname(filename); 689out: 690 return error; 691} 692 693#define top_esp (THREAD_SIZE - sizeof(unsigned long)) 694#define top_ebp (THREAD_SIZE - 2*sizeof(unsigned long)) 695 696unsigned long get_wchan(struct task_struct *p) 697{ 698 unsigned long bp, sp, ip; 699 unsigned long stack_page; 700 int count = 0; 701 if (!p || p == current || p->state == TASK_RUNNING) 702 return 0; 703 stack_page = (unsigned long)task_stack_page(p); 704 sp = p->thread.sp; 705 if (!stack_page || sp < stack_page || sp > top_esp+stack_page) 706 return 0; 707 /* include/asm-i386/system.h:switch_to() pushes bp last. */ 708 bp = *(unsigned long *) sp; 709 do { 710 if (bp < stack_page || bp > top_ebp+stack_page) 711 return 0; 712 ip = *(unsigned long *) (bp+4); 713 if (!in_sched_functions(ip)) 714 return ip; 715 bp = *(unsigned long *) bp; 716 } while (count++ < 16); 717 return 0; 718} 719 720unsigned long arch_align_stack(unsigned long sp) 721{ 722 if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space) 723 sp -= get_random_int() % 8192; 724 return sp & ~0xf; 725} 726 727unsigned long arch_randomize_brk(struct mm_struct *mm) 728{ 729 unsigned long range_end = mm->brk + 0x02000000; 730 return randomize_range(mm->brk, range_end, 0) ? : mm->brk; 731} 732