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