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/a.out.h> 27 #include <linux/interrupt.h> 28 #include <linux/utsname.h> 29 #include <linux/delay.h> 30 #include <linux/reboot.h> 31 #include <linux/init.h> 32 #include <linux/mc146818rtc.h> 33 #include <linux/module.h> 34 #include <linux/kallsyms.h> 35 #include <linux/ptrace.h> 36 #include <linux/random.h> 37 #include <linux/personality.h> 38 #include <linux/tick.h> 39 #include <linux/percpu.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 #include <asm/vm86.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 59 asmlinkage void ret_from_fork(void) __asm__("ret_from_fork"); 60 61 static int hlt_counter; 62 63 unsigned long boot_option_idle_override = 0; 64 EXPORT_SYMBOL(boot_option_idle_override); 65 66 DEFINE_PER_CPU(struct task_struct *, current_task) = &init_task; 67 EXPORT_PER_CPU_SYMBOL(current_task); 68 69 DEFINE_PER_CPU(int, cpu_number); 70 EXPORT_PER_CPU_SYMBOL(cpu_number); 71 72 /* 73 * Return saved PC of a blocked thread. 74 */ 75 unsigned long thread_saved_pc(struct task_struct *tsk) 76 { 77 return ((unsigned long *)tsk->thread.esp)[3]; 78 } 79 80 /* 81 * Powermanagement idle function, if any.. 82 */ 83 void (*pm_idle)(void); 84 EXPORT_SYMBOL(pm_idle); 85 static DEFINE_PER_CPU(unsigned int, cpu_idle_state); 86 87 void disable_hlt(void) 88 { 89 hlt_counter++; 90 } 91 92 EXPORT_SYMBOL(disable_hlt); 93 94 void enable_hlt(void) 95 { 96 hlt_counter--; 97 } 98 99 EXPORT_SYMBOL(enable_hlt); 100 101 /* 102 * We use this if we don't have any better 103 * idle routine.. 104 */ 105 void default_idle(void) 106 { 107 if (!hlt_counter && boot_cpu_data.hlt_works_ok) { 108 current_thread_info()->status &= ~TS_POLLING; 109 /* 110 * TS_POLLING-cleared state must be visible before we 111 * test NEED_RESCHED: 112 */ 113 smp_mb(); 114 115 local_irq_disable(); 116 if (!need_resched()) 117 safe_halt(); /* enables interrupts racelessly */ 118 else 119 local_irq_enable(); 120 current_thread_info()->status |= TS_POLLING; 121 } else { 122 /* loop is done by the caller */ 123 cpu_relax(); 124 } 125 } 126 #ifdef CONFIG_APM_MODULE 127 EXPORT_SYMBOL(default_idle); 128 #endif 129 130 /* 131 * On SMP it's slightly faster (but much more power-consuming!) 132 * to poll the ->work.need_resched flag instead of waiting for the 133 * cross-CPU IPI to arrive. Use this option with caution. 134 */ 135 static void poll_idle (void) 136 { 137 cpu_relax(); 138 } 139 140 #ifdef CONFIG_HOTPLUG_CPU 141 #include <asm/nmi.h> 142 /* We don't actually take CPU down, just spin without interrupts. */ 143 static inline void play_dead(void) 144 { 145 /* This must be done before dead CPU ack */ 146 cpu_exit_clear(); 147 wbinvd(); 148 mb(); 149 /* Ack it */ 150 __get_cpu_var(cpu_state) = CPU_DEAD; 151 152 /* 153 * With physical CPU hotplug, we should halt the cpu 154 */ 155 local_irq_disable(); 156 while (1) 157 halt(); 158 } 159 #else 160 static inline void play_dead(void) 161 { 162 BUG(); 163 } 164 #endif /* CONFIG_HOTPLUG_CPU */ 165 166 /* 167 * The idle thread. There's no useful work to be 168 * done, so just try to conserve power and have a 169 * low exit latency (ie sit in a loop waiting for 170 * somebody to say that they'd like to reschedule) 171 */ 172 void cpu_idle(void) 173 { 174 int cpu = smp_processor_id(); 175 176 current_thread_info()->status |= TS_POLLING; 177 178 /* endless idle loop with no priority at all */ 179 while (1) { 180 tick_nohz_stop_sched_tick(); 181 while (!need_resched()) { 182 void (*idle)(void); 183 184 if (__get_cpu_var(cpu_idle_state)) 185 __get_cpu_var(cpu_idle_state) = 0; 186 187 check_pgt_cache(); 188 rmb(); 189 idle = pm_idle; 190 191 if (!idle) 192 idle = default_idle; 193 194 if (cpu_is_offline(cpu)) 195 play_dead(); 196 197 __get_cpu_var(irq_stat).idle_timestamp = jiffies; 198 idle(); 199 } 200 tick_nohz_restart_sched_tick(); 201 preempt_enable_no_resched(); 202 schedule(); 203 preempt_disable(); 204 } 205 } 206 207 static void do_nothing(void *unused) 208 { 209 } 210 211 void cpu_idle_wait(void) 212 { 213 unsigned int cpu, this_cpu = get_cpu(); 214 cpumask_t map, tmp = current->cpus_allowed; 215 216 set_cpus_allowed(current, cpumask_of_cpu(this_cpu)); 217 put_cpu(); 218 219 cpus_clear(map); 220 for_each_online_cpu(cpu) { 221 per_cpu(cpu_idle_state, cpu) = 1; 222 cpu_set(cpu, map); 223 } 224 225 __get_cpu_var(cpu_idle_state) = 0; 226 227 wmb(); 228 do { 229 ssleep(1); 230 for_each_online_cpu(cpu) { 231 if (cpu_isset(cpu, map) && !per_cpu(cpu_idle_state, cpu)) 232 cpu_clear(cpu, map); 233 } 234 cpus_and(map, map, cpu_online_map); 235 /* 236 * We waited 1 sec, if a CPU still did not call idle 237 * it may be because it is in idle and not waking up 238 * because it has nothing to do. 239 * Give all the remaining CPUS a kick. 240 */ 241 smp_call_function_mask(map, do_nothing, 0, 0); 242 } while (!cpus_empty(map)); 243 244 set_cpus_allowed(current, tmp); 245 } 246 EXPORT_SYMBOL_GPL(cpu_idle_wait); 247 248 /* 249 * This uses new MONITOR/MWAIT instructions on P4 processors with PNI, 250 * which can obviate IPI to trigger checking of need_resched. 251 * We execute MONITOR against need_resched and enter optimized wait state 252 * through MWAIT. Whenever someone changes need_resched, we would be woken 253 * up from MWAIT (without an IPI). 254 * 255 * New with Core Duo processors, MWAIT can take some hints based on CPU 256 * capability. 257 */ 258 void mwait_idle_with_hints(unsigned long eax, unsigned long ecx) 259 { 260 if (!need_resched()) { 261 __monitor((void *)¤t_thread_info()->flags, 0, 0); 262 smp_mb(); 263 if (!need_resched()) 264 __mwait(eax, ecx); 265 } 266 } 267 268 /* Default MONITOR/MWAIT with no hints, used for default C1 state */ 269 static void mwait_idle(void) 270 { 271 local_irq_enable(); 272 mwait_idle_with_hints(0, 0); 273 } 274 275 void __cpuinit select_idle_routine(const struct cpuinfo_x86 *c) 276 { 277 if (cpu_has(c, X86_FEATURE_MWAIT)) { 278 printk("monitor/mwait feature present.\n"); 279 /* 280 * Skip, if setup has overridden idle. 281 * One CPU supports mwait => All CPUs supports mwait 282 */ 283 if (!pm_idle) { 284 printk("using mwait in idle threads.\n"); 285 pm_idle = mwait_idle; 286 } 287 } 288 } 289 290 static int __init idle_setup(char *str) 291 { 292 if (!strcmp(str, "poll")) { 293 printk("using polling idle threads.\n"); 294 pm_idle = poll_idle; 295 #ifdef CONFIG_X86_SMP 296 if (smp_num_siblings > 1) 297 printk("WARNING: polling idle and HT enabled, performance may degrade.\n"); 298 #endif 299 } else if (!strcmp(str, "mwait")) 300 force_mwait = 1; 301 else 302 return -1; 303 304 boot_option_idle_override = 1; 305 return 0; 306 } 307 early_param("idle", idle_setup); 308 309 void __show_registers(struct pt_regs *regs, int all) 310 { 311 unsigned long cr0 = 0L, cr2 = 0L, cr3 = 0L, cr4 = 0L; 312 unsigned long d0, d1, d2, d3, d6, d7; 313 unsigned long esp; 314 unsigned short ss, gs; 315 316 if (user_mode_vm(regs)) { 317 esp = regs->esp; 318 ss = regs->xss & 0xffff; 319 savesegment(gs, gs); 320 } else { 321 esp = (unsigned long) (®s->esp); 322 savesegment(ss, ss); 323 savesegment(gs, gs); 324 } 325 326 printk("\n"); 327 printk("Pid: %d, comm: %s %s (%s %.*s)\n", 328 task_pid_nr(current), current->comm, 329 print_tainted(), init_utsname()->release, 330 (int)strcspn(init_utsname()->version, " "), 331 init_utsname()->version); 332 333 printk("EIP: %04x:[<%08lx>] EFLAGS: %08lx CPU: %d\n", 334 0xffff & regs->xcs, regs->eip, regs->eflags, 335 smp_processor_id()); 336 print_symbol("EIP is at %s\n", regs->eip); 337 338 printk("EAX: %08lx EBX: %08lx ECX: %08lx EDX: %08lx\n", 339 regs->eax, regs->ebx, regs->ecx, regs->edx); 340 printk("ESI: %08lx EDI: %08lx EBP: %08lx ESP: %08lx\n", 341 regs->esi, regs->edi, regs->ebp, esp); 342 printk(" DS: %04x ES: %04x FS: %04x GS: %04x SS: %04x\n", 343 regs->xds & 0xffff, regs->xes & 0xffff, 344 regs->xfs & 0xffff, gs, ss); 345 346 if (!all) 347 return; 348 349 cr0 = read_cr0(); 350 cr2 = read_cr2(); 351 cr3 = read_cr3(); 352 cr4 = read_cr4_safe(); 353 printk("CR0: %08lx CR2: %08lx CR3: %08lx CR4: %08lx\n", 354 cr0, cr2, cr3, cr4); 355 356 get_debugreg(d0, 0); 357 get_debugreg(d1, 1); 358 get_debugreg(d2, 2); 359 get_debugreg(d3, 3); 360 printk("DR0: %08lx DR1: %08lx DR2: %08lx DR3: %08lx\n", 361 d0, d1, d2, d3); 362 363 get_debugreg(d6, 6); 364 get_debugreg(d7, 7); 365 printk("DR6: %08lx DR7: %08lx\n", 366 d6, d7); 367 } 368 369 void show_regs(struct pt_regs *regs) 370 { 371 __show_registers(regs, 1); 372 show_trace(NULL, regs, ®s->esp); 373 } 374 375 /* 376 * This gets run with %ebx containing the 377 * function to call, and %edx containing 378 * the "args". 379 */ 380 extern void kernel_thread_helper(void); 381 382 /* 383 * Create a kernel thread 384 */ 385 int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags) 386 { 387 struct pt_regs regs; 388 389 memset(®s, 0, sizeof(regs)); 390 391 regs.ebx = (unsigned long) fn; 392 regs.edx = (unsigned long) arg; 393 394 regs.xds = __USER_DS; 395 regs.xes = __USER_DS; 396 regs.xfs = __KERNEL_PERCPU; 397 regs.orig_eax = -1; 398 regs.eip = (unsigned long) kernel_thread_helper; 399 regs.xcs = __KERNEL_CS | get_kernel_rpl(); 400 regs.eflags = X86_EFLAGS_IF | X86_EFLAGS_SF | X86_EFLAGS_PF | 0x2; 401 402 /* Ok, create the new process.. */ 403 return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, ®s, 0, NULL, NULL); 404 } 405 EXPORT_SYMBOL(kernel_thread); 406 407 /* 408 * Free current thread data structures etc.. 409 */ 410 void exit_thread(void) 411 { 412 /* The process may have allocated an io port bitmap... nuke it. */ 413 if (unlikely(test_thread_flag(TIF_IO_BITMAP))) { 414 struct task_struct *tsk = current; 415 struct thread_struct *t = &tsk->thread; 416 int cpu = get_cpu(); 417 struct tss_struct *tss = &per_cpu(init_tss, cpu); 418 419 kfree(t->io_bitmap_ptr); 420 t->io_bitmap_ptr = NULL; 421 clear_thread_flag(TIF_IO_BITMAP); 422 /* 423 * Careful, clear this in the TSS too: 424 */ 425 memset(tss->io_bitmap, 0xff, tss->io_bitmap_max); 426 t->io_bitmap_max = 0; 427 tss->io_bitmap_owner = NULL; 428 tss->io_bitmap_max = 0; 429 tss->x86_tss.io_bitmap_base = INVALID_IO_BITMAP_OFFSET; 430 put_cpu(); 431 } 432 } 433 434 void flush_thread(void) 435 { 436 struct task_struct *tsk = current; 437 438 memset(tsk->thread.debugreg, 0, sizeof(unsigned long)*8); 439 memset(tsk->thread.tls_array, 0, sizeof(tsk->thread.tls_array)); 440 clear_tsk_thread_flag(tsk, TIF_DEBUG); 441 /* 442 * Forget coprocessor state.. 443 */ 444 clear_fpu(tsk); 445 clear_used_math(); 446 } 447 448 void release_thread(struct task_struct *dead_task) 449 { 450 BUG_ON(dead_task->mm); 451 release_vm86_irqs(dead_task); 452 } 453 454 /* 455 * This gets called before we allocate a new thread and copy 456 * the current task into it. 457 */ 458 void prepare_to_copy(struct task_struct *tsk) 459 { 460 unlazy_fpu(tsk); 461 } 462 463 int copy_thread(int nr, unsigned long clone_flags, unsigned long esp, 464 unsigned long unused, 465 struct task_struct * p, struct pt_regs * regs) 466 { 467 struct pt_regs * childregs; 468 struct task_struct *tsk; 469 int err; 470 471 childregs = task_pt_regs(p); 472 *childregs = *regs; 473 childregs->eax = 0; 474 childregs->esp = esp; 475 476 p->thread.esp = (unsigned long) childregs; 477 p->thread.esp0 = (unsigned long) (childregs+1); 478 479 p->thread.eip = (unsigned long) ret_from_fork; 480 481 savesegment(gs,p->thread.gs); 482 483 tsk = current; 484 if (unlikely(test_tsk_thread_flag(tsk, TIF_IO_BITMAP))) { 485 p->thread.io_bitmap_ptr = kmemdup(tsk->thread.io_bitmap_ptr, 486 IO_BITMAP_BYTES, GFP_KERNEL); 487 if (!p->thread.io_bitmap_ptr) { 488 p->thread.io_bitmap_max = 0; 489 return -ENOMEM; 490 } 491 set_tsk_thread_flag(p, TIF_IO_BITMAP); 492 } 493 494 /* 495 * Set a new TLS for the child thread? 496 */ 497 if (clone_flags & CLONE_SETTLS) { 498 struct desc_struct *desc; 499 struct user_desc info; 500 int idx; 501 502 err = -EFAULT; 503 if (copy_from_user(&info, (void __user *)childregs->esi, sizeof(info))) 504 goto out; 505 err = -EINVAL; 506 if (LDT_empty(&info)) 507 goto out; 508 509 idx = info.entry_number; 510 if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX) 511 goto out; 512 513 desc = p->thread.tls_array + idx - GDT_ENTRY_TLS_MIN; 514 desc->a = LDT_entry_a(&info); 515 desc->b = LDT_entry_b(&info); 516 } 517 518 err = 0; 519 out: 520 if (err && p->thread.io_bitmap_ptr) { 521 kfree(p->thread.io_bitmap_ptr); 522 p->thread.io_bitmap_max = 0; 523 } 524 return err; 525 } 526 527 /* 528 * fill in the user structure for a core dump.. 529 */ 530 void dump_thread(struct pt_regs * regs, struct user * dump) 531 { 532 int i; 533 534 /* changed the size calculations - should hopefully work better. lbt */ 535 dump->magic = CMAGIC; 536 dump->start_code = 0; 537 dump->start_stack = regs->esp & ~(PAGE_SIZE - 1); 538 dump->u_tsize = ((unsigned long) current->mm->end_code) >> PAGE_SHIFT; 539 dump->u_dsize = ((unsigned long) (current->mm->brk + (PAGE_SIZE-1))) >> PAGE_SHIFT; 540 dump->u_dsize -= dump->u_tsize; 541 dump->u_ssize = 0; 542 for (i = 0; i < 8; i++) 543 dump->u_debugreg[i] = current->thread.debugreg[i]; 544 545 if (dump->start_stack < TASK_SIZE) 546 dump->u_ssize = ((unsigned long) (TASK_SIZE - dump->start_stack)) >> PAGE_SHIFT; 547 548 dump->regs.ebx = regs->ebx; 549 dump->regs.ecx = regs->ecx; 550 dump->regs.edx = regs->edx; 551 dump->regs.esi = regs->esi; 552 dump->regs.edi = regs->edi; 553 dump->regs.ebp = regs->ebp; 554 dump->regs.eax = regs->eax; 555 dump->regs.ds = regs->xds; 556 dump->regs.es = regs->xes; 557 dump->regs.fs = regs->xfs; 558 savesegment(gs,dump->regs.gs); 559 dump->regs.orig_eax = regs->orig_eax; 560 dump->regs.eip = regs->eip; 561 dump->regs.cs = regs->xcs; 562 dump->regs.eflags = regs->eflags; 563 dump->regs.esp = regs->esp; 564 dump->regs.ss = regs->xss; 565 566 dump->u_fpvalid = dump_fpu (regs, &dump->i387); 567 } 568 EXPORT_SYMBOL(dump_thread); 569 570 /* 571 * Capture the user space registers if the task is not running (in user space) 572 */ 573 int dump_task_regs(struct task_struct *tsk, elf_gregset_t *regs) 574 { 575 struct pt_regs ptregs = *task_pt_regs(tsk); 576 ptregs.xcs &= 0xffff; 577 ptregs.xds &= 0xffff; 578 ptregs.xes &= 0xffff; 579 ptregs.xss &= 0xffff; 580 581 elf_core_copy_regs(regs, &ptregs); 582 583 return 1; 584 } 585 586 #ifdef CONFIG_SECCOMP 587 void hard_disable_TSC(void) 588 { 589 write_cr4(read_cr4() | X86_CR4_TSD); 590 } 591 void disable_TSC(void) 592 { 593 preempt_disable(); 594 if (!test_and_set_thread_flag(TIF_NOTSC)) 595 /* 596 * Must flip the CPU state synchronously with 597 * TIF_NOTSC in the current running context. 598 */ 599 hard_disable_TSC(); 600 preempt_enable(); 601 } 602 void hard_enable_TSC(void) 603 { 604 write_cr4(read_cr4() & ~X86_CR4_TSD); 605 } 606 #endif /* CONFIG_SECCOMP */ 607 608 static noinline void 609 __switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p, 610 struct tss_struct *tss) 611 { 612 struct thread_struct *next; 613 614 next = &next_p->thread; 615 616 if (test_tsk_thread_flag(next_p, TIF_DEBUG)) { 617 set_debugreg(next->debugreg[0], 0); 618 set_debugreg(next->debugreg[1], 1); 619 set_debugreg(next->debugreg[2], 2); 620 set_debugreg(next->debugreg[3], 3); 621 /* no 4 and 5 */ 622 set_debugreg(next->debugreg[6], 6); 623 set_debugreg(next->debugreg[7], 7); 624 } 625 626 #ifdef CONFIG_SECCOMP 627 if (test_tsk_thread_flag(prev_p, TIF_NOTSC) ^ 628 test_tsk_thread_flag(next_p, TIF_NOTSC)) { 629 /* prev and next are different */ 630 if (test_tsk_thread_flag(next_p, TIF_NOTSC)) 631 hard_disable_TSC(); 632 else 633 hard_enable_TSC(); 634 } 635 #endif 636 637 if (!test_tsk_thread_flag(next_p, TIF_IO_BITMAP)) { 638 /* 639 * Disable the bitmap via an invalid offset. We still cache 640 * the previous bitmap owner and the IO bitmap contents: 641 */ 642 tss->x86_tss.io_bitmap_base = INVALID_IO_BITMAP_OFFSET; 643 return; 644 } 645 646 if (likely(next == tss->io_bitmap_owner)) { 647 /* 648 * Previous owner of the bitmap (hence the bitmap content) 649 * matches the next task, we dont have to do anything but 650 * to set a valid offset in the TSS: 651 */ 652 tss->x86_tss.io_bitmap_base = IO_BITMAP_OFFSET; 653 return; 654 } 655 /* 656 * Lazy TSS's I/O bitmap copy. We set an invalid offset here 657 * and we let the task to get a GPF in case an I/O instruction 658 * is performed. The handler of the GPF will verify that the 659 * faulting task has a valid I/O bitmap and, it true, does the 660 * real copy and restart the instruction. This will save us 661 * redundant copies when the currently switched task does not 662 * perform any I/O during its timeslice. 663 */ 664 tss->x86_tss.io_bitmap_base = INVALID_IO_BITMAP_OFFSET_LAZY; 665 } 666 667 /* 668 * switch_to(x,yn) should switch tasks from x to y. 669 * 670 * We fsave/fwait so that an exception goes off at the right time 671 * (as a call from the fsave or fwait in effect) rather than to 672 * the wrong process. Lazy FP saving no longer makes any sense 673 * with modern CPU's, and this simplifies a lot of things (SMP 674 * and UP become the same). 675 * 676 * NOTE! We used to use the x86 hardware context switching. The 677 * reason for not using it any more becomes apparent when you 678 * try to recover gracefully from saved state that is no longer 679 * valid (stale segment register values in particular). With the 680 * hardware task-switch, there is no way to fix up bad state in 681 * a reasonable manner. 682 * 683 * The fact that Intel documents the hardware task-switching to 684 * be slow is a fairly red herring - this code is not noticeably 685 * faster. However, there _is_ some room for improvement here, 686 * so the performance issues may eventually be a valid point. 687 * More important, however, is the fact that this allows us much 688 * more flexibility. 689 * 690 * The return value (in %eax) will be the "prev" task after 691 * the task-switch, and shows up in ret_from_fork in entry.S, 692 * for example. 693 */ 694 struct task_struct fastcall * __switch_to(struct task_struct *prev_p, struct task_struct *next_p) 695 { 696 struct thread_struct *prev = &prev_p->thread, 697 *next = &next_p->thread; 698 int cpu = smp_processor_id(); 699 struct tss_struct *tss = &per_cpu(init_tss, cpu); 700 701 /* never put a printk in __switch_to... printk() calls wake_up*() indirectly */ 702 703 __unlazy_fpu(prev_p); 704 705 706 /* we're going to use this soon, after a few expensive things */ 707 if (next_p->fpu_counter > 5) 708 prefetch(&next->i387.fxsave); 709 710 /* 711 * Reload esp0. 712 */ 713 load_esp0(tss, next); 714 715 /* 716 * Save away %gs. No need to save %fs, as it was saved on the 717 * stack on entry. No need to save %es and %ds, as those are 718 * always kernel segments while inside the kernel. Doing this 719 * before setting the new TLS descriptors avoids the situation 720 * where we temporarily have non-reloadable segments in %fs 721 * and %gs. This could be an issue if the NMI handler ever 722 * used %fs or %gs (it does not today), or if the kernel is 723 * running inside of a hypervisor layer. 724 */ 725 savesegment(gs, prev->gs); 726 727 /* 728 * Load the per-thread Thread-Local Storage descriptor. 729 */ 730 load_TLS(next, cpu); 731 732 /* 733 * Restore IOPL if needed. In normal use, the flags restore 734 * in the switch assembly will handle this. But if the kernel 735 * is running virtualized at a non-zero CPL, the popf will 736 * not restore flags, so it must be done in a separate step. 737 */ 738 if (get_kernel_rpl() && unlikely(prev->iopl != next->iopl)) 739 set_iopl_mask(next->iopl); 740 741 /* 742 * Now maybe handle debug registers and/or IO bitmaps 743 */ 744 if (unlikely(task_thread_info(prev_p)->flags & _TIF_WORK_CTXSW_PREV || 745 task_thread_info(next_p)->flags & _TIF_WORK_CTXSW_NEXT)) 746 __switch_to_xtra(prev_p, next_p, tss); 747 748 /* 749 * Leave lazy mode, flushing any hypercalls made here. 750 * This must be done before restoring TLS segments so 751 * the GDT and LDT are properly updated, and must be 752 * done before math_state_restore, so the TS bit is up 753 * to date. 754 */ 755 arch_leave_lazy_cpu_mode(); 756 757 /* If the task has used fpu the last 5 timeslices, just do a full 758 * restore of the math state immediately to avoid the trap; the 759 * chances of needing FPU soon are obviously high now 760 */ 761 if (next_p->fpu_counter > 5) 762 math_state_restore(); 763 764 /* 765 * Restore %gs if needed (which is common) 766 */ 767 if (prev->gs | next->gs) 768 loadsegment(gs, next->gs); 769 770 x86_write_percpu(current_task, next_p); 771 772 return prev_p; 773 } 774 775 asmlinkage int sys_fork(struct pt_regs regs) 776 { 777 return do_fork(SIGCHLD, regs.esp, ®s, 0, NULL, NULL); 778 } 779 780 asmlinkage int sys_clone(struct pt_regs regs) 781 { 782 unsigned long clone_flags; 783 unsigned long newsp; 784 int __user *parent_tidptr, *child_tidptr; 785 786 clone_flags = regs.ebx; 787 newsp = regs.ecx; 788 parent_tidptr = (int __user *)regs.edx; 789 child_tidptr = (int __user *)regs.edi; 790 if (!newsp) 791 newsp = regs.esp; 792 return do_fork(clone_flags, newsp, ®s, 0, parent_tidptr, child_tidptr); 793 } 794 795 /* 796 * This is trivial, and on the face of it looks like it 797 * could equally well be done in user mode. 798 * 799 * Not so, for quite unobvious reasons - register pressure. 800 * In user mode vfork() cannot have a stack frame, and if 801 * done by calling the "clone()" system call directly, you 802 * do not have enough call-clobbered registers to hold all 803 * the information you need. 804 */ 805 asmlinkage int sys_vfork(struct pt_regs regs) 806 { 807 return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, regs.esp, ®s, 0, NULL, NULL); 808 } 809 810 /* 811 * sys_execve() executes a new program. 812 */ 813 asmlinkage int sys_execve(struct pt_regs regs) 814 { 815 int error; 816 char * filename; 817 818 filename = getname((char __user *) regs.ebx); 819 error = PTR_ERR(filename); 820 if (IS_ERR(filename)) 821 goto out; 822 error = do_execve(filename, 823 (char __user * __user *) regs.ecx, 824 (char __user * __user *) regs.edx, 825 ®s); 826 if (error == 0) { 827 task_lock(current); 828 current->ptrace &= ~PT_DTRACE; 829 task_unlock(current); 830 /* Make sure we don't return using sysenter.. */ 831 set_thread_flag(TIF_IRET); 832 } 833 putname(filename); 834 out: 835 return error; 836 } 837 838 #define top_esp (THREAD_SIZE - sizeof(unsigned long)) 839 #define top_ebp (THREAD_SIZE - 2*sizeof(unsigned long)) 840 841 unsigned long get_wchan(struct task_struct *p) 842 { 843 unsigned long ebp, esp, eip; 844 unsigned long stack_page; 845 int count = 0; 846 if (!p || p == current || p->state == TASK_RUNNING) 847 return 0; 848 stack_page = (unsigned long)task_stack_page(p); 849 esp = p->thread.esp; 850 if (!stack_page || esp < stack_page || esp > top_esp+stack_page) 851 return 0; 852 /* include/asm-i386/system.h:switch_to() pushes ebp last. */ 853 ebp = *(unsigned long *) esp; 854 do { 855 if (ebp < stack_page || ebp > top_ebp+stack_page) 856 return 0; 857 eip = *(unsigned long *) (ebp+4); 858 if (!in_sched_functions(eip)) 859 return eip; 860 ebp = *(unsigned long *) ebp; 861 } while (count++ < 16); 862 return 0; 863 } 864 865 /* 866 * sys_alloc_thread_area: get a yet unused TLS descriptor index. 867 */ 868 static int get_free_idx(void) 869 { 870 struct thread_struct *t = ¤t->thread; 871 int idx; 872 873 for (idx = 0; idx < GDT_ENTRY_TLS_ENTRIES; idx++) 874 if (desc_empty(t->tls_array + idx)) 875 return idx + GDT_ENTRY_TLS_MIN; 876 return -ESRCH; 877 } 878 879 /* 880 * Set a given TLS descriptor: 881 */ 882 asmlinkage int sys_set_thread_area(struct user_desc __user *u_info) 883 { 884 struct thread_struct *t = ¤t->thread; 885 struct user_desc info; 886 struct desc_struct *desc; 887 int cpu, idx; 888 889 if (copy_from_user(&info, u_info, sizeof(info))) 890 return -EFAULT; 891 idx = info.entry_number; 892 893 /* 894 * index -1 means the kernel should try to find and 895 * allocate an empty descriptor: 896 */ 897 if (idx == -1) { 898 idx = get_free_idx(); 899 if (idx < 0) 900 return idx; 901 if (put_user(idx, &u_info->entry_number)) 902 return -EFAULT; 903 } 904 905 if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX) 906 return -EINVAL; 907 908 desc = t->tls_array + idx - GDT_ENTRY_TLS_MIN; 909 910 /* 911 * We must not get preempted while modifying the TLS. 912 */ 913 cpu = get_cpu(); 914 915 if (LDT_empty(&info)) { 916 desc->a = 0; 917 desc->b = 0; 918 } else { 919 desc->a = LDT_entry_a(&info); 920 desc->b = LDT_entry_b(&info); 921 } 922 load_TLS(t, cpu); 923 924 put_cpu(); 925 926 return 0; 927 } 928 929 /* 930 * Get the current Thread-Local Storage area: 931 */ 932 933 #define GET_BASE(desc) ( \ 934 (((desc)->a >> 16) & 0x0000ffff) | \ 935 (((desc)->b << 16) & 0x00ff0000) | \ 936 ( (desc)->b & 0xff000000) ) 937 938 #define GET_LIMIT(desc) ( \ 939 ((desc)->a & 0x0ffff) | \ 940 ((desc)->b & 0xf0000) ) 941 942 #define GET_32BIT(desc) (((desc)->b >> 22) & 1) 943 #define GET_CONTENTS(desc) (((desc)->b >> 10) & 3) 944 #define GET_WRITABLE(desc) (((desc)->b >> 9) & 1) 945 #define GET_LIMIT_PAGES(desc) (((desc)->b >> 23) & 1) 946 #define GET_PRESENT(desc) (((desc)->b >> 15) & 1) 947 #define GET_USEABLE(desc) (((desc)->b >> 20) & 1) 948 949 asmlinkage int sys_get_thread_area(struct user_desc __user *u_info) 950 { 951 struct user_desc info; 952 struct desc_struct *desc; 953 int idx; 954 955 if (get_user(idx, &u_info->entry_number)) 956 return -EFAULT; 957 if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX) 958 return -EINVAL; 959 960 memset(&info, 0, sizeof(info)); 961 962 desc = current->thread.tls_array + idx - GDT_ENTRY_TLS_MIN; 963 964 info.entry_number = idx; 965 info.base_addr = GET_BASE(desc); 966 info.limit = GET_LIMIT(desc); 967 info.seg_32bit = GET_32BIT(desc); 968 info.contents = GET_CONTENTS(desc); 969 info.read_exec_only = !GET_WRITABLE(desc); 970 info.limit_in_pages = GET_LIMIT_PAGES(desc); 971 info.seg_not_present = !GET_PRESENT(desc); 972 info.useable = GET_USEABLE(desc); 973 974 if (copy_to_user(u_info, &info, sizeof(info))) 975 return -EFAULT; 976 return 0; 977 } 978 979 unsigned long arch_align_stack(unsigned long sp) 980 { 981 if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space) 982 sp -= get_random_int() % 8192; 983 return sp & ~0xf; 984 } 985