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 #include <linux/dmi.h> 41 42 #include <asm/uaccess.h> 43 #include <asm/pgtable.h> 44 #include <asm/system.h> 45 #include <asm/io.h> 46 #include <asm/ldt.h> 47 #include <asm/processor.h> 48 #include <asm/i387.h> 49 #include <asm/desc.h> 50 #ifdef CONFIG_MATH_EMULATION 51 #include <asm/math_emu.h> 52 #endif 53 54 #include <linux/err.h> 55 56 #include <asm/tlbflush.h> 57 #include <asm/cpu.h> 58 #include <asm/kdebug.h> 59 #include <asm/idle.h> 60 #include <asm/syscalls.h> 61 #include <asm/smp.h> 62 63 asmlinkage void ret_from_fork(void) __asm__("ret_from_fork"); 64 65 DEFINE_PER_CPU(struct task_struct *, current_task) = &init_task; 66 EXPORT_PER_CPU_SYMBOL(current_task); 67 68 DEFINE_PER_CPU(int, cpu_number); 69 EXPORT_PER_CPU_SYMBOL(cpu_number); 70 71 /* 72 * Return saved PC of a blocked thread. 73 */ 74 unsigned long thread_saved_pc(struct task_struct *tsk) 75 { 76 return ((unsigned long *)tsk->thread.sp)[3]; 77 } 78 79 #ifndef CONFIG_SMP 80 static inline void play_dead(void) 81 { 82 BUG(); 83 } 84 #endif 85 86 /* 87 * The idle thread. There's no useful work to be 88 * done, so just try to conserve power and have a 89 * low exit latency (ie sit in a loop waiting for 90 * somebody to say that they'd like to reschedule) 91 */ 92 void cpu_idle(void) 93 { 94 int cpu = smp_processor_id(); 95 96 current_thread_info()->status |= TS_POLLING; 97 98 /* endless idle loop with no priority at all */ 99 while (1) { 100 tick_nohz_stop_sched_tick(1); 101 while (!need_resched()) { 102 103 check_pgt_cache(); 104 rmb(); 105 106 if (rcu_pending(cpu)) 107 rcu_check_callbacks(cpu, 0); 108 109 if (cpu_is_offline(cpu)) 110 play_dead(); 111 112 local_irq_disable(); 113 __get_cpu_var(irq_stat).idle_timestamp = jiffies; 114 /* Don't trace irqs off for idle */ 115 stop_critical_timings(); 116 pm_idle(); 117 start_critical_timings(); 118 } 119 tick_nohz_restart_sched_tick(); 120 preempt_enable_no_resched(); 121 schedule(); 122 preempt_disable(); 123 } 124 } 125 126 void __show_regs(struct pt_regs *regs, int all) 127 { 128 unsigned long cr0 = 0L, cr2 = 0L, cr3 = 0L, cr4 = 0L; 129 unsigned long d0, d1, d2, d3, d6, d7; 130 unsigned long sp; 131 unsigned short ss, gs; 132 const char *board; 133 134 if (user_mode_vm(regs)) { 135 sp = regs->sp; 136 ss = regs->ss & 0xffff; 137 savesegment(gs, gs); 138 } else { 139 sp = (unsigned long) (®s->sp); 140 savesegment(ss, ss); 141 savesegment(gs, gs); 142 } 143 144 printk("\n"); 145 146 board = dmi_get_system_info(DMI_PRODUCT_NAME); 147 if (!board) 148 board = ""; 149 printk("Pid: %d, comm: %s %s (%s %.*s) %s\n", 150 task_pid_nr(current), current->comm, 151 print_tainted(), init_utsname()->release, 152 (int)strcspn(init_utsname()->version, " "), 153 init_utsname()->version, board); 154 155 printk("EIP: %04x:[<%08lx>] EFLAGS: %08lx CPU: %d\n", 156 (u16)regs->cs, regs->ip, regs->flags, 157 smp_processor_id()); 158 print_symbol("EIP is at %s\n", regs->ip); 159 160 printk("EAX: %08lx EBX: %08lx ECX: %08lx EDX: %08lx\n", 161 regs->ax, regs->bx, regs->cx, regs->dx); 162 printk("ESI: %08lx EDI: %08lx EBP: %08lx ESP: %08lx\n", 163 regs->si, regs->di, regs->bp, sp); 164 printk(" DS: %04x ES: %04x FS: %04x GS: %04x SS: %04x\n", 165 (u16)regs->ds, (u16)regs->es, (u16)regs->fs, gs, ss); 166 167 if (!all) 168 return; 169 170 cr0 = read_cr0(); 171 cr2 = read_cr2(); 172 cr3 = read_cr3(); 173 cr4 = read_cr4_safe(); 174 printk("CR0: %08lx CR2: %08lx CR3: %08lx CR4: %08lx\n", 175 cr0, cr2, cr3, cr4); 176 177 get_debugreg(d0, 0); 178 get_debugreg(d1, 1); 179 get_debugreg(d2, 2); 180 get_debugreg(d3, 3); 181 printk("DR0: %08lx DR1: %08lx DR2: %08lx DR3: %08lx\n", 182 d0, d1, d2, d3); 183 184 get_debugreg(d6, 6); 185 get_debugreg(d7, 7); 186 printk("DR6: %08lx DR7: %08lx\n", 187 d6, d7); 188 } 189 190 void show_regs(struct pt_regs *regs) 191 { 192 __show_regs(regs, 1); 193 show_trace(NULL, regs, ®s->sp, regs->bp); 194 } 195 196 /* 197 * This gets run with %bx containing the 198 * function to call, and %dx containing 199 * the "args". 200 */ 201 extern void kernel_thread_helper(void); 202 203 /* 204 * Create a kernel thread 205 */ 206 int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags) 207 { 208 struct pt_regs regs; 209 210 memset(®s, 0, sizeof(regs)); 211 212 regs.bx = (unsigned long) fn; 213 regs.dx = (unsigned long) arg; 214 215 regs.ds = __USER_DS; 216 regs.es = __USER_DS; 217 regs.fs = __KERNEL_PERCPU; 218 regs.orig_ax = -1; 219 regs.ip = (unsigned long) kernel_thread_helper; 220 regs.cs = __KERNEL_CS | get_kernel_rpl(); 221 regs.flags = X86_EFLAGS_IF | X86_EFLAGS_SF | X86_EFLAGS_PF | 0x2; 222 223 /* Ok, create the new process.. */ 224 return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, ®s, 0, NULL, NULL); 225 } 226 EXPORT_SYMBOL(kernel_thread); 227 228 /* 229 * Free current thread data structures etc.. 230 */ 231 void exit_thread(void) 232 { 233 /* The process may have allocated an io port bitmap... nuke it. */ 234 if (unlikely(test_thread_flag(TIF_IO_BITMAP))) { 235 struct task_struct *tsk = current; 236 struct thread_struct *t = &tsk->thread; 237 int cpu = get_cpu(); 238 struct tss_struct *tss = &per_cpu(init_tss, cpu); 239 240 kfree(t->io_bitmap_ptr); 241 t->io_bitmap_ptr = NULL; 242 clear_thread_flag(TIF_IO_BITMAP); 243 /* 244 * Careful, clear this in the TSS too: 245 */ 246 memset(tss->io_bitmap, 0xff, tss->io_bitmap_max); 247 t->io_bitmap_max = 0; 248 tss->io_bitmap_owner = NULL; 249 tss->io_bitmap_max = 0; 250 tss->x86_tss.io_bitmap_base = INVALID_IO_BITMAP_OFFSET; 251 put_cpu(); 252 } 253 #ifdef CONFIG_X86_DS 254 /* Free any DS contexts that have not been properly released. */ 255 if (unlikely(current->thread.ds_ctx)) { 256 /* we clear debugctl to make sure DS is not used. */ 257 update_debugctlmsr(0); 258 ds_free(current->thread.ds_ctx); 259 } 260 #endif /* CONFIG_X86_DS */ 261 } 262 263 void flush_thread(void) 264 { 265 struct task_struct *tsk = current; 266 267 tsk->thread.debugreg0 = 0; 268 tsk->thread.debugreg1 = 0; 269 tsk->thread.debugreg2 = 0; 270 tsk->thread.debugreg3 = 0; 271 tsk->thread.debugreg6 = 0; 272 tsk->thread.debugreg7 = 0; 273 memset(tsk->thread.tls_array, 0, sizeof(tsk->thread.tls_array)); 274 clear_tsk_thread_flag(tsk, TIF_DEBUG); 275 /* 276 * Forget coprocessor state.. 277 */ 278 tsk->fpu_counter = 0; 279 clear_fpu(tsk); 280 clear_used_math(); 281 } 282 283 void release_thread(struct task_struct *dead_task) 284 { 285 BUG_ON(dead_task->mm); 286 release_vm86_irqs(dead_task); 287 } 288 289 /* 290 * This gets called before we allocate a new thread and copy 291 * the current task into it. 292 */ 293 void prepare_to_copy(struct task_struct *tsk) 294 { 295 unlazy_fpu(tsk); 296 } 297 298 int copy_thread(int nr, unsigned long clone_flags, unsigned long sp, 299 unsigned long unused, 300 struct task_struct * p, struct pt_regs * regs) 301 { 302 struct pt_regs * childregs; 303 struct task_struct *tsk; 304 int err; 305 306 childregs = task_pt_regs(p); 307 *childregs = *regs; 308 childregs->ax = 0; 309 childregs->sp = sp; 310 311 p->thread.sp = (unsigned long) childregs; 312 p->thread.sp0 = (unsigned long) (childregs+1); 313 314 p->thread.ip = (unsigned long) ret_from_fork; 315 316 savesegment(gs, p->thread.gs); 317 318 tsk = current; 319 if (unlikely(test_tsk_thread_flag(tsk, TIF_IO_BITMAP))) { 320 p->thread.io_bitmap_ptr = kmemdup(tsk->thread.io_bitmap_ptr, 321 IO_BITMAP_BYTES, GFP_KERNEL); 322 if (!p->thread.io_bitmap_ptr) { 323 p->thread.io_bitmap_max = 0; 324 return -ENOMEM; 325 } 326 set_tsk_thread_flag(p, TIF_IO_BITMAP); 327 } 328 329 err = 0; 330 331 /* 332 * Set a new TLS for the child thread? 333 */ 334 if (clone_flags & CLONE_SETTLS) 335 err = do_set_thread_area(p, -1, 336 (struct user_desc __user *)childregs->si, 0); 337 338 if (err && p->thread.io_bitmap_ptr) { 339 kfree(p->thread.io_bitmap_ptr); 340 p->thread.io_bitmap_max = 0; 341 } 342 return err; 343 } 344 345 void 346 start_thread(struct pt_regs *regs, unsigned long new_ip, unsigned long new_sp) 347 { 348 __asm__("movl %0, %%gs" :: "r"(0)); 349 regs->fs = 0; 350 set_fs(USER_DS); 351 regs->ds = __USER_DS; 352 regs->es = __USER_DS; 353 regs->ss = __USER_DS; 354 regs->cs = __USER_CS; 355 regs->ip = new_ip; 356 regs->sp = new_sp; 357 /* 358 * Free the old FP and other extended state 359 */ 360 free_thread_xstate(current); 361 } 362 EXPORT_SYMBOL_GPL(start_thread); 363 364 static void hard_disable_TSC(void) 365 { 366 write_cr4(read_cr4() | X86_CR4_TSD); 367 } 368 369 void disable_TSC(void) 370 { 371 preempt_disable(); 372 if (!test_and_set_thread_flag(TIF_NOTSC)) 373 /* 374 * Must flip the CPU state synchronously with 375 * TIF_NOTSC in the current running context. 376 */ 377 hard_disable_TSC(); 378 preempt_enable(); 379 } 380 381 static void hard_enable_TSC(void) 382 { 383 write_cr4(read_cr4() & ~X86_CR4_TSD); 384 } 385 386 static void enable_TSC(void) 387 { 388 preempt_disable(); 389 if (test_and_clear_thread_flag(TIF_NOTSC)) 390 /* 391 * Must flip the CPU state synchronously with 392 * TIF_NOTSC in the current running context. 393 */ 394 hard_enable_TSC(); 395 preempt_enable(); 396 } 397 398 int get_tsc_mode(unsigned long adr) 399 { 400 unsigned int val; 401 402 if (test_thread_flag(TIF_NOTSC)) 403 val = PR_TSC_SIGSEGV; 404 else 405 val = PR_TSC_ENABLE; 406 407 return put_user(val, (unsigned int __user *)adr); 408 } 409 410 int set_tsc_mode(unsigned int val) 411 { 412 if (val == PR_TSC_SIGSEGV) 413 disable_TSC(); 414 else if (val == PR_TSC_ENABLE) 415 enable_TSC(); 416 else 417 return -EINVAL; 418 419 return 0; 420 } 421 422 #ifdef CONFIG_X86_DS 423 static int update_debugctl(struct thread_struct *prev, 424 struct thread_struct *next, unsigned long debugctl) 425 { 426 unsigned long ds_prev = 0; 427 unsigned long ds_next = 0; 428 429 if (prev->ds_ctx) 430 ds_prev = (unsigned long)prev->ds_ctx->ds; 431 if (next->ds_ctx) 432 ds_next = (unsigned long)next->ds_ctx->ds; 433 434 if (ds_next != ds_prev) { 435 /* we clear debugctl to make sure DS 436 * is not in use when we change it */ 437 debugctl = 0; 438 update_debugctlmsr(0); 439 wrmsr(MSR_IA32_DS_AREA, ds_next, 0); 440 } 441 return debugctl; 442 } 443 #else 444 static int update_debugctl(struct thread_struct *prev, 445 struct thread_struct *next, unsigned long debugctl) 446 { 447 return debugctl; 448 } 449 #endif /* CONFIG_X86_DS */ 450 451 static noinline void 452 __switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p, 453 struct tss_struct *tss) 454 { 455 struct thread_struct *prev, *next; 456 unsigned long debugctl; 457 458 prev = &prev_p->thread; 459 next = &next_p->thread; 460 461 debugctl = update_debugctl(prev, next, prev->debugctlmsr); 462 463 if (next->debugctlmsr != debugctl) 464 update_debugctlmsr(next->debugctlmsr); 465 466 if (test_tsk_thread_flag(next_p, TIF_DEBUG)) { 467 set_debugreg(next->debugreg0, 0); 468 set_debugreg(next->debugreg1, 1); 469 set_debugreg(next->debugreg2, 2); 470 set_debugreg(next->debugreg3, 3); 471 /* no 4 and 5 */ 472 set_debugreg(next->debugreg6, 6); 473 set_debugreg(next->debugreg7, 7); 474 } 475 476 if (test_tsk_thread_flag(prev_p, TIF_NOTSC) ^ 477 test_tsk_thread_flag(next_p, TIF_NOTSC)) { 478 /* prev and next are different */ 479 if (test_tsk_thread_flag(next_p, TIF_NOTSC)) 480 hard_disable_TSC(); 481 else 482 hard_enable_TSC(); 483 } 484 485 #ifdef CONFIG_X86_PTRACE_BTS 486 if (test_tsk_thread_flag(prev_p, TIF_BTS_TRACE_TS)) 487 ptrace_bts_take_timestamp(prev_p, BTS_TASK_DEPARTS); 488 489 if (test_tsk_thread_flag(next_p, TIF_BTS_TRACE_TS)) 490 ptrace_bts_take_timestamp(next_p, BTS_TASK_ARRIVES); 491 #endif /* CONFIG_X86_PTRACE_BTS */ 492 493 494 if (!test_tsk_thread_flag(next_p, TIF_IO_BITMAP)) { 495 /* 496 * Disable the bitmap via an invalid offset. We still cache 497 * the previous bitmap owner and the IO bitmap contents: 498 */ 499 tss->x86_tss.io_bitmap_base = INVALID_IO_BITMAP_OFFSET; 500 return; 501 } 502 503 if (likely(next == tss->io_bitmap_owner)) { 504 /* 505 * Previous owner of the bitmap (hence the bitmap content) 506 * matches the next task, we dont have to do anything but 507 * to set a valid offset in the TSS: 508 */ 509 tss->x86_tss.io_bitmap_base = IO_BITMAP_OFFSET; 510 return; 511 } 512 /* 513 * Lazy TSS's I/O bitmap copy. We set an invalid offset here 514 * and we let the task to get a GPF in case an I/O instruction 515 * is performed. The handler of the GPF will verify that the 516 * faulting task has a valid I/O bitmap and, it true, does the 517 * real copy and restart the instruction. This will save us 518 * redundant copies when the currently switched task does not 519 * perform any I/O during its timeslice. 520 */ 521 tss->x86_tss.io_bitmap_base = INVALID_IO_BITMAP_OFFSET_LAZY; 522 } 523 524 /* 525 * switch_to(x,yn) should switch tasks from x to y. 526 * 527 * We fsave/fwait so that an exception goes off at the right time 528 * (as a call from the fsave or fwait in effect) rather than to 529 * the wrong process. Lazy FP saving no longer makes any sense 530 * with modern CPU's, and this simplifies a lot of things (SMP 531 * and UP become the same). 532 * 533 * NOTE! We used to use the x86 hardware context switching. The 534 * reason for not using it any more becomes apparent when you 535 * try to recover gracefully from saved state that is no longer 536 * valid (stale segment register values in particular). With the 537 * hardware task-switch, there is no way to fix up bad state in 538 * a reasonable manner. 539 * 540 * The fact that Intel documents the hardware task-switching to 541 * be slow is a fairly red herring - this code is not noticeably 542 * faster. However, there _is_ some room for improvement here, 543 * so the performance issues may eventually be a valid point. 544 * More important, however, is the fact that this allows us much 545 * more flexibility. 546 * 547 * The return value (in %ax) will be the "prev" task after 548 * the task-switch, and shows up in ret_from_fork in entry.S, 549 * for example. 550 */ 551 struct task_struct * __switch_to(struct task_struct *prev_p, struct task_struct *next_p) 552 { 553 struct thread_struct *prev = &prev_p->thread, 554 *next = &next_p->thread; 555 int cpu = smp_processor_id(); 556 struct tss_struct *tss = &per_cpu(init_tss, cpu); 557 558 /* never put a printk in __switch_to... printk() calls wake_up*() indirectly */ 559 560 __unlazy_fpu(prev_p); 561 562 563 /* we're going to use this soon, after a few expensive things */ 564 if (next_p->fpu_counter > 5) 565 prefetch(next->xstate); 566 567 /* 568 * Reload esp0. 569 */ 570 load_sp0(tss, next); 571 572 /* 573 * Save away %gs. No need to save %fs, as it was saved on the 574 * stack on entry. No need to save %es and %ds, as those are 575 * always kernel segments while inside the kernel. Doing this 576 * before setting the new TLS descriptors avoids the situation 577 * where we temporarily have non-reloadable segments in %fs 578 * and %gs. This could be an issue if the NMI handler ever 579 * used %fs or %gs (it does not today), or if the kernel is 580 * running inside of a hypervisor layer. 581 */ 582 savesegment(gs, prev->gs); 583 584 /* 585 * Load the per-thread Thread-Local Storage descriptor. 586 */ 587 load_TLS(next, cpu); 588 589 /* 590 * Restore IOPL if needed. In normal use, the flags restore 591 * in the switch assembly will handle this. But if the kernel 592 * is running virtualized at a non-zero CPL, the popf will 593 * not restore flags, so it must be done in a separate step. 594 */ 595 if (get_kernel_rpl() && unlikely(prev->iopl != next->iopl)) 596 set_iopl_mask(next->iopl); 597 598 /* 599 * Now maybe handle debug registers and/or IO bitmaps 600 */ 601 if (unlikely(task_thread_info(prev_p)->flags & _TIF_WORK_CTXSW_PREV || 602 task_thread_info(next_p)->flags & _TIF_WORK_CTXSW_NEXT)) 603 __switch_to_xtra(prev_p, next_p, tss); 604 605 /* 606 * Leave lazy mode, flushing any hypercalls made here. 607 * This must be done before restoring TLS segments so 608 * the GDT and LDT are properly updated, and must be 609 * done before math_state_restore, so the TS bit is up 610 * to date. 611 */ 612 arch_leave_lazy_cpu_mode(); 613 614 /* If the task has used fpu the last 5 timeslices, just do a full 615 * restore of the math state immediately to avoid the trap; the 616 * chances of needing FPU soon are obviously high now 617 * 618 * tsk_used_math() checks prevent calling math_state_restore(), 619 * which can sleep in the case of !tsk_used_math() 620 */ 621 if (tsk_used_math(next_p) && next_p->fpu_counter > 5) 622 math_state_restore(); 623 624 /* 625 * Restore %gs if needed (which is common) 626 */ 627 if (prev->gs | next->gs) 628 loadsegment(gs, next->gs); 629 630 x86_write_percpu(current_task, next_p); 631 632 return prev_p; 633 } 634 635 asmlinkage int sys_fork(struct pt_regs regs) 636 { 637 return do_fork(SIGCHLD, regs.sp, ®s, 0, NULL, NULL); 638 } 639 640 asmlinkage int sys_clone(struct pt_regs regs) 641 { 642 unsigned long clone_flags; 643 unsigned long newsp; 644 int __user *parent_tidptr, *child_tidptr; 645 646 clone_flags = regs.bx; 647 newsp = regs.cx; 648 parent_tidptr = (int __user *)regs.dx; 649 child_tidptr = (int __user *)regs.di; 650 if (!newsp) 651 newsp = regs.sp; 652 return do_fork(clone_flags, newsp, ®s, 0, parent_tidptr, child_tidptr); 653 } 654 655 /* 656 * This is trivial, and on the face of it looks like it 657 * could equally well be done in user mode. 658 * 659 * Not so, for quite unobvious reasons - register pressure. 660 * In user mode vfork() cannot have a stack frame, and if 661 * done by calling the "clone()" system call directly, you 662 * do not have enough call-clobbered registers to hold all 663 * the information you need. 664 */ 665 asmlinkage int sys_vfork(struct pt_regs regs) 666 { 667 return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, regs.sp, ®s, 0, NULL, NULL); 668 } 669 670 /* 671 * sys_execve() executes a new program. 672 */ 673 asmlinkage int sys_execve(struct pt_regs regs) 674 { 675 int error; 676 char * filename; 677 678 filename = getname((char __user *) regs.bx); 679 error = PTR_ERR(filename); 680 if (IS_ERR(filename)) 681 goto out; 682 error = do_execve(filename, 683 (char __user * __user *) regs.cx, 684 (char __user * __user *) regs.dx, 685 ®s); 686 if (error == 0) { 687 /* Make sure we don't return using sysenter.. */ 688 set_thread_flag(TIF_IRET); 689 } 690 putname(filename); 691 out: 692 return error; 693 } 694 695 #define top_esp (THREAD_SIZE - sizeof(unsigned long)) 696 #define top_ebp (THREAD_SIZE - 2*sizeof(unsigned long)) 697 698 unsigned long get_wchan(struct task_struct *p) 699 { 700 unsigned long bp, sp, ip; 701 unsigned long stack_page; 702 int count = 0; 703 if (!p || p == current || p->state == TASK_RUNNING) 704 return 0; 705 stack_page = (unsigned long)task_stack_page(p); 706 sp = p->thread.sp; 707 if (!stack_page || sp < stack_page || sp > top_esp+stack_page) 708 return 0; 709 /* include/asm-i386/system.h:switch_to() pushes bp last. */ 710 bp = *(unsigned long *) sp; 711 do { 712 if (bp < stack_page || bp > top_ebp+stack_page) 713 return 0; 714 ip = *(unsigned long *) (bp+4); 715 if (!in_sched_functions(ip)) 716 return ip; 717 bp = *(unsigned long *) bp; 718 } while (count++ < 16); 719 return 0; 720 } 721 722 unsigned long arch_align_stack(unsigned long sp) 723 { 724 if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space) 725 sp -= get_random_int() % 8192; 726 return sp & ~0xf; 727 } 728 729 unsigned long arch_randomize_brk(struct mm_struct *mm) 730 { 731 unsigned long range_end = mm->brk + 0x02000000; 732 return randomize_range(mm->brk, range_end, 0) ? : mm->brk; 733 } 734