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