1 /* 2 * Copyright (C) 1995 Linus Torvalds 3 * 4 * Pentium III FXSR, SSE support 5 * Gareth Hughes <gareth@valinux.com>, May 2000 6 * 7 * X86-64 port 8 * Andi Kleen. 9 * 10 * CPU hotplug support - ashok.raj@intel.com 11 */ 12 13 /* 14 * This file handles the architecture-dependent parts of process handling.. 15 */ 16 17 #include <linux/stackprotector.h> 18 #include <linux/cpu.h> 19 #include <linux/errno.h> 20 #include <linux/sched.h> 21 #include <linux/fs.h> 22 #include <linux/kernel.h> 23 #include <linux/mm.h> 24 #include <linux/elfcore.h> 25 #include <linux/smp.h> 26 #include <linux/slab.h> 27 #include <linux/user.h> 28 #include <linux/interrupt.h> 29 #include <linux/delay.h> 30 #include <linux/module.h> 31 #include <linux/ptrace.h> 32 #include <linux/notifier.h> 33 #include <linux/kprobes.h> 34 #include <linux/kdebug.h> 35 #include <linux/tick.h> 36 #include <linux/prctl.h> 37 #include <linux/uaccess.h> 38 #include <linux/io.h> 39 #include <linux/ftrace.h> 40 41 #include <asm/pgtable.h> 42 #include <asm/system.h> 43 #include <asm/processor.h> 44 #include <asm/i387.h> 45 #include <asm/mmu_context.h> 46 #include <asm/prctl.h> 47 #include <asm/desc.h> 48 #include <asm/proto.h> 49 #include <asm/ia32.h> 50 #include <asm/idle.h> 51 #include <asm/syscalls.h> 52 #include <asm/debugreg.h> 53 54 #include <trace/events/power.h> 55 56 asmlinkage extern void ret_from_fork(void); 57 58 DEFINE_PER_CPU(unsigned long, old_rsp); 59 static DEFINE_PER_CPU(unsigned char, is_idle); 60 61 static ATOMIC_NOTIFIER_HEAD(idle_notifier); 62 63 void idle_notifier_register(struct notifier_block *n) 64 { 65 atomic_notifier_chain_register(&idle_notifier, n); 66 } 67 EXPORT_SYMBOL_GPL(idle_notifier_register); 68 69 void idle_notifier_unregister(struct notifier_block *n) 70 { 71 atomic_notifier_chain_unregister(&idle_notifier, n); 72 } 73 EXPORT_SYMBOL_GPL(idle_notifier_unregister); 74 75 void enter_idle(void) 76 { 77 percpu_write(is_idle, 1); 78 atomic_notifier_call_chain(&idle_notifier, IDLE_START, NULL); 79 } 80 81 static void __exit_idle(void) 82 { 83 if (x86_test_and_clear_bit_percpu(0, is_idle) == 0) 84 return; 85 atomic_notifier_call_chain(&idle_notifier, IDLE_END, NULL); 86 } 87 88 /* Called from interrupts to signify idle end */ 89 void exit_idle(void) 90 { 91 /* idle loop has pid 0 */ 92 if (current->pid) 93 return; 94 __exit_idle(); 95 } 96 97 #ifndef CONFIG_SMP 98 static inline void play_dead(void) 99 { 100 BUG(); 101 } 102 #endif 103 104 /* 105 * The idle thread. There's no useful work to be 106 * done, so just try to conserve power and have a 107 * low exit latency (ie sit in a loop waiting for 108 * somebody to say that they'd like to reschedule) 109 */ 110 void cpu_idle(void) 111 { 112 current_thread_info()->status |= TS_POLLING; 113 114 /* 115 * If we're the non-boot CPU, nothing set the stack canary up 116 * for us. CPU0 already has it initialized but no harm in 117 * doing it again. This is a good place for updating it, as 118 * we wont ever return from this function (so the invalid 119 * canaries already on the stack wont ever trigger). 120 */ 121 boot_init_stack_canary(); 122 123 /* endless idle loop with no priority at all */ 124 while (1) { 125 tick_nohz_stop_sched_tick(1); 126 while (!need_resched()) { 127 128 rmb(); 129 130 if (cpu_is_offline(smp_processor_id())) 131 play_dead(); 132 /* 133 * Idle routines should keep interrupts disabled 134 * from here on, until they go to idle. 135 * Otherwise, idle callbacks can misfire. 136 */ 137 local_irq_disable(); 138 enter_idle(); 139 /* Don't trace irqs off for idle */ 140 stop_critical_timings(); 141 pm_idle(); 142 start_critical_timings(); 143 144 trace_power_end(smp_processor_id()); 145 146 /* In many cases the interrupt that ended idle 147 has already called exit_idle. But some idle 148 loops can be woken up without interrupt. */ 149 __exit_idle(); 150 } 151 152 tick_nohz_restart_sched_tick(); 153 preempt_enable_no_resched(); 154 schedule(); 155 preempt_disable(); 156 } 157 } 158 159 /* Prints also some state that isn't saved in the pt_regs */ 160 void __show_regs(struct pt_regs *regs, int all) 161 { 162 unsigned long cr0 = 0L, cr2 = 0L, cr3 = 0L, cr4 = 0L, fs, gs, shadowgs; 163 unsigned long d0, d1, d2, d3, d6, d7; 164 unsigned int fsindex, gsindex; 165 unsigned int ds, cs, es; 166 167 show_regs_common(); 168 printk(KERN_DEFAULT "RIP: %04lx:[<%016lx>] ", regs->cs & 0xffff, regs->ip); 169 printk_address(regs->ip, 1); 170 printk(KERN_DEFAULT "RSP: %04lx:%016lx EFLAGS: %08lx\n", regs->ss, 171 regs->sp, regs->flags); 172 printk(KERN_DEFAULT "RAX: %016lx RBX: %016lx RCX: %016lx\n", 173 regs->ax, regs->bx, regs->cx); 174 printk(KERN_DEFAULT "RDX: %016lx RSI: %016lx RDI: %016lx\n", 175 regs->dx, regs->si, regs->di); 176 printk(KERN_DEFAULT "RBP: %016lx R08: %016lx R09: %016lx\n", 177 regs->bp, regs->r8, regs->r9); 178 printk(KERN_DEFAULT "R10: %016lx R11: %016lx R12: %016lx\n", 179 regs->r10, regs->r11, regs->r12); 180 printk(KERN_DEFAULT "R13: %016lx R14: %016lx R15: %016lx\n", 181 regs->r13, regs->r14, regs->r15); 182 183 asm("movl %%ds,%0" : "=r" (ds)); 184 asm("movl %%cs,%0" : "=r" (cs)); 185 asm("movl %%es,%0" : "=r" (es)); 186 asm("movl %%fs,%0" : "=r" (fsindex)); 187 asm("movl %%gs,%0" : "=r" (gsindex)); 188 189 rdmsrl(MSR_FS_BASE, fs); 190 rdmsrl(MSR_GS_BASE, gs); 191 rdmsrl(MSR_KERNEL_GS_BASE, shadowgs); 192 193 if (!all) 194 return; 195 196 cr0 = read_cr0(); 197 cr2 = read_cr2(); 198 cr3 = read_cr3(); 199 cr4 = read_cr4(); 200 201 printk(KERN_DEFAULT "FS: %016lx(%04x) GS:%016lx(%04x) knlGS:%016lx\n", 202 fs, fsindex, gs, gsindex, shadowgs); 203 printk(KERN_DEFAULT "CS: %04x DS: %04x ES: %04x CR0: %016lx\n", cs, ds, 204 es, cr0); 205 printk(KERN_DEFAULT "CR2: %016lx CR3: %016lx CR4: %016lx\n", cr2, cr3, 206 cr4); 207 208 get_debugreg(d0, 0); 209 get_debugreg(d1, 1); 210 get_debugreg(d2, 2); 211 printk(KERN_DEFAULT "DR0: %016lx DR1: %016lx DR2: %016lx\n", d0, d1, d2); 212 get_debugreg(d3, 3); 213 get_debugreg(d6, 6); 214 get_debugreg(d7, 7); 215 printk(KERN_DEFAULT "DR3: %016lx DR6: %016lx DR7: %016lx\n", d3, d6, d7); 216 } 217 218 void release_thread(struct task_struct *dead_task) 219 { 220 if (dead_task->mm) { 221 if (dead_task->mm->context.size) { 222 printk("WARNING: dead process %8s still has LDT? <%p/%d>\n", 223 dead_task->comm, 224 dead_task->mm->context.ldt, 225 dead_task->mm->context.size); 226 BUG(); 227 } 228 } 229 } 230 231 static inline void set_32bit_tls(struct task_struct *t, int tls, u32 addr) 232 { 233 struct user_desc ud = { 234 .base_addr = addr, 235 .limit = 0xfffff, 236 .seg_32bit = 1, 237 .limit_in_pages = 1, 238 .useable = 1, 239 }; 240 struct desc_struct *desc = t->thread.tls_array; 241 desc += tls; 242 fill_ldt(desc, &ud); 243 } 244 245 static inline u32 read_32bit_tls(struct task_struct *t, int tls) 246 { 247 return get_desc_base(&t->thread.tls_array[tls]); 248 } 249 250 /* 251 * This gets called before we allocate a new thread and copy 252 * the current task into it. 253 */ 254 void prepare_to_copy(struct task_struct *tsk) 255 { 256 unlazy_fpu(tsk); 257 } 258 259 int copy_thread(unsigned long clone_flags, unsigned long sp, 260 unsigned long unused, 261 struct task_struct *p, struct pt_regs *regs) 262 { 263 int err; 264 struct pt_regs *childregs; 265 struct task_struct *me = current; 266 267 childregs = ((struct pt_regs *) 268 (THREAD_SIZE + task_stack_page(p))) - 1; 269 *childregs = *regs; 270 271 childregs->ax = 0; 272 if (user_mode(regs)) 273 childregs->sp = sp; 274 else 275 childregs->sp = (unsigned long)childregs; 276 277 p->thread.sp = (unsigned long) childregs; 278 p->thread.sp0 = (unsigned long) (childregs+1); 279 p->thread.usersp = me->thread.usersp; 280 281 set_tsk_thread_flag(p, TIF_FORK); 282 283 p->thread.io_bitmap_ptr = NULL; 284 285 savesegment(gs, p->thread.gsindex); 286 p->thread.gs = p->thread.gsindex ? 0 : me->thread.gs; 287 savesegment(fs, p->thread.fsindex); 288 p->thread.fs = p->thread.fsindex ? 0 : me->thread.fs; 289 savesegment(es, p->thread.es); 290 savesegment(ds, p->thread.ds); 291 292 err = -ENOMEM; 293 memset(p->thread.ptrace_bps, 0, sizeof(p->thread.ptrace_bps)); 294 295 if (unlikely(test_tsk_thread_flag(me, TIF_IO_BITMAP))) { 296 p->thread.io_bitmap_ptr = kmalloc(IO_BITMAP_BYTES, GFP_KERNEL); 297 if (!p->thread.io_bitmap_ptr) { 298 p->thread.io_bitmap_max = 0; 299 return -ENOMEM; 300 } 301 memcpy(p->thread.io_bitmap_ptr, me->thread.io_bitmap_ptr, 302 IO_BITMAP_BYTES); 303 set_tsk_thread_flag(p, TIF_IO_BITMAP); 304 } 305 306 /* 307 * Set a new TLS for the child thread? 308 */ 309 if (clone_flags & CLONE_SETTLS) { 310 #ifdef CONFIG_IA32_EMULATION 311 if (test_thread_flag(TIF_IA32)) 312 err = do_set_thread_area(p, -1, 313 (struct user_desc __user *)childregs->si, 0); 314 else 315 #endif 316 err = do_arch_prctl(p, ARCH_SET_FS, childregs->r8); 317 if (err) 318 goto out; 319 } 320 err = 0; 321 out: 322 if (err && p->thread.io_bitmap_ptr) { 323 kfree(p->thread.io_bitmap_ptr); 324 p->thread.io_bitmap_max = 0; 325 } 326 327 return err; 328 } 329 330 static void 331 start_thread_common(struct pt_regs *regs, unsigned long new_ip, 332 unsigned long new_sp, 333 unsigned int _cs, unsigned int _ss, unsigned int _ds) 334 { 335 loadsegment(fs, 0); 336 loadsegment(es, _ds); 337 loadsegment(ds, _ds); 338 load_gs_index(0); 339 regs->ip = new_ip; 340 regs->sp = new_sp; 341 percpu_write(old_rsp, new_sp); 342 regs->cs = _cs; 343 regs->ss = _ss; 344 regs->flags = X86_EFLAGS_IF; 345 set_fs(USER_DS); 346 /* 347 * Free the old FP and other extended state 348 */ 349 free_thread_xstate(current); 350 } 351 352 void 353 start_thread(struct pt_regs *regs, unsigned long new_ip, unsigned long new_sp) 354 { 355 start_thread_common(regs, new_ip, new_sp, 356 __USER_CS, __USER_DS, 0); 357 } 358 359 #ifdef CONFIG_IA32_EMULATION 360 void start_thread_ia32(struct pt_regs *regs, u32 new_ip, u32 new_sp) 361 { 362 start_thread_common(regs, new_ip, new_sp, 363 __USER32_CS, __USER32_DS, __USER32_DS); 364 } 365 #endif 366 367 /* 368 * switch_to(x,y) should switch tasks from x to y. 369 * 370 * This could still be optimized: 371 * - fold all the options into a flag word and test it with a single test. 372 * - could test fs/gs bitsliced 373 * 374 * Kprobes not supported here. Set the probe on schedule instead. 375 * Function graph tracer not supported too. 376 */ 377 __notrace_funcgraph struct task_struct * 378 __switch_to(struct task_struct *prev_p, struct task_struct *next_p) 379 { 380 struct thread_struct *prev = &prev_p->thread; 381 struct thread_struct *next = &next_p->thread; 382 int cpu = smp_processor_id(); 383 struct tss_struct *tss = &per_cpu(init_tss, cpu); 384 unsigned fsindex, gsindex; 385 bool preload_fpu; 386 387 /* 388 * If the task has used fpu the last 5 timeslices, just do a full 389 * restore of the math state immediately to avoid the trap; the 390 * chances of needing FPU soon are obviously high now 391 */ 392 preload_fpu = tsk_used_math(next_p) && next_p->fpu_counter > 5; 393 394 /* we're going to use this soon, after a few expensive things */ 395 if (preload_fpu) 396 prefetch(next->fpu.state); 397 398 /* 399 * Reload esp0, LDT and the page table pointer: 400 */ 401 load_sp0(tss, next); 402 403 /* 404 * Switch DS and ES. 405 * This won't pick up thread selector changes, but I guess that is ok. 406 */ 407 savesegment(es, prev->es); 408 if (unlikely(next->es | prev->es)) 409 loadsegment(es, next->es); 410 411 savesegment(ds, prev->ds); 412 if (unlikely(next->ds | prev->ds)) 413 loadsegment(ds, next->ds); 414 415 416 /* We must save %fs and %gs before load_TLS() because 417 * %fs and %gs may be cleared by load_TLS(). 418 * 419 * (e.g. xen_load_tls()) 420 */ 421 savesegment(fs, fsindex); 422 savesegment(gs, gsindex); 423 424 load_TLS(next, cpu); 425 426 /* Must be after DS reload */ 427 __unlazy_fpu(prev_p); 428 429 /* Make sure cpu is ready for new context */ 430 if (preload_fpu) 431 clts(); 432 433 /* 434 * Leave lazy mode, flushing any hypercalls made here. 435 * This must be done before restoring TLS segments so 436 * the GDT and LDT are properly updated, and must be 437 * done before math_state_restore, so the TS bit is up 438 * to date. 439 */ 440 arch_end_context_switch(next_p); 441 442 /* 443 * Switch FS and GS. 444 * 445 * Segment register != 0 always requires a reload. Also 446 * reload when it has changed. When prev process used 64bit 447 * base always reload to avoid an information leak. 448 */ 449 if (unlikely(fsindex | next->fsindex | prev->fs)) { 450 loadsegment(fs, next->fsindex); 451 /* 452 * Check if the user used a selector != 0; if yes 453 * clear 64bit base, since overloaded base is always 454 * mapped to the Null selector 455 */ 456 if (fsindex) 457 prev->fs = 0; 458 } 459 /* when next process has a 64bit base use it */ 460 if (next->fs) 461 wrmsrl(MSR_FS_BASE, next->fs); 462 prev->fsindex = fsindex; 463 464 if (unlikely(gsindex | next->gsindex | prev->gs)) { 465 load_gs_index(next->gsindex); 466 if (gsindex) 467 prev->gs = 0; 468 } 469 if (next->gs) 470 wrmsrl(MSR_KERNEL_GS_BASE, next->gs); 471 prev->gsindex = gsindex; 472 473 /* 474 * Switch the PDA and FPU contexts. 475 */ 476 prev->usersp = percpu_read(old_rsp); 477 percpu_write(old_rsp, next->usersp); 478 percpu_write(current_task, next_p); 479 480 percpu_write(kernel_stack, 481 (unsigned long)task_stack_page(next_p) + 482 THREAD_SIZE - KERNEL_STACK_OFFSET); 483 484 /* 485 * Now maybe reload the debug registers and handle I/O bitmaps 486 */ 487 if (unlikely(task_thread_info(next_p)->flags & _TIF_WORK_CTXSW_NEXT || 488 task_thread_info(prev_p)->flags & _TIF_WORK_CTXSW_PREV)) 489 __switch_to_xtra(prev_p, next_p, tss); 490 491 /* 492 * Preload the FPU context, now that we've determined that the 493 * task is likely to be using it. 494 */ 495 if (preload_fpu) 496 __math_state_restore(); 497 498 return prev_p; 499 } 500 501 void set_personality_64bit(void) 502 { 503 /* inherit personality from parent */ 504 505 /* Make sure to be in 64bit mode */ 506 clear_thread_flag(TIF_IA32); 507 508 /* TBD: overwrites user setup. Should have two bits. 509 But 64bit processes have always behaved this way, 510 so it's not too bad. The main problem is just that 511 32bit childs are affected again. */ 512 current->personality &= ~READ_IMPLIES_EXEC; 513 } 514 515 void set_personality_ia32(void) 516 { 517 /* inherit personality from parent */ 518 519 /* Make sure to be in 32bit mode */ 520 set_thread_flag(TIF_IA32); 521 current->personality |= force_personality32; 522 523 /* Prepare the first "return" to user space */ 524 current_thread_info()->status |= TS_COMPAT; 525 } 526 527 unsigned long get_wchan(struct task_struct *p) 528 { 529 unsigned long stack; 530 u64 fp, ip; 531 int count = 0; 532 533 if (!p || p == current || p->state == TASK_RUNNING) 534 return 0; 535 stack = (unsigned long)task_stack_page(p); 536 if (p->thread.sp < stack || p->thread.sp >= stack+THREAD_SIZE) 537 return 0; 538 fp = *(u64 *)(p->thread.sp); 539 do { 540 if (fp < (unsigned long)stack || 541 fp >= (unsigned long)stack+THREAD_SIZE) 542 return 0; 543 ip = *(u64 *)(fp+8); 544 if (!in_sched_functions(ip)) 545 return ip; 546 fp = *(u64 *)fp; 547 } while (count++ < 16); 548 return 0; 549 } 550 551 long do_arch_prctl(struct task_struct *task, int code, unsigned long addr) 552 { 553 int ret = 0; 554 int doit = task == current; 555 int cpu; 556 557 switch (code) { 558 case ARCH_SET_GS: 559 if (addr >= TASK_SIZE_OF(task)) 560 return -EPERM; 561 cpu = get_cpu(); 562 /* handle small bases via the GDT because that's faster to 563 switch. */ 564 if (addr <= 0xffffffff) { 565 set_32bit_tls(task, GS_TLS, addr); 566 if (doit) { 567 load_TLS(&task->thread, cpu); 568 load_gs_index(GS_TLS_SEL); 569 } 570 task->thread.gsindex = GS_TLS_SEL; 571 task->thread.gs = 0; 572 } else { 573 task->thread.gsindex = 0; 574 task->thread.gs = addr; 575 if (doit) { 576 load_gs_index(0); 577 ret = checking_wrmsrl(MSR_KERNEL_GS_BASE, addr); 578 } 579 } 580 put_cpu(); 581 break; 582 case ARCH_SET_FS: 583 /* Not strictly needed for fs, but do it for symmetry 584 with gs */ 585 if (addr >= TASK_SIZE_OF(task)) 586 return -EPERM; 587 cpu = get_cpu(); 588 /* handle small bases via the GDT because that's faster to 589 switch. */ 590 if (addr <= 0xffffffff) { 591 set_32bit_tls(task, FS_TLS, addr); 592 if (doit) { 593 load_TLS(&task->thread, cpu); 594 loadsegment(fs, FS_TLS_SEL); 595 } 596 task->thread.fsindex = FS_TLS_SEL; 597 task->thread.fs = 0; 598 } else { 599 task->thread.fsindex = 0; 600 task->thread.fs = addr; 601 if (doit) { 602 /* set the selector to 0 to not confuse 603 __switch_to */ 604 loadsegment(fs, 0); 605 ret = checking_wrmsrl(MSR_FS_BASE, addr); 606 } 607 } 608 put_cpu(); 609 break; 610 case ARCH_GET_FS: { 611 unsigned long base; 612 if (task->thread.fsindex == FS_TLS_SEL) 613 base = read_32bit_tls(task, FS_TLS); 614 else if (doit) 615 rdmsrl(MSR_FS_BASE, base); 616 else 617 base = task->thread.fs; 618 ret = put_user(base, (unsigned long __user *)addr); 619 break; 620 } 621 case ARCH_GET_GS: { 622 unsigned long base; 623 unsigned gsindex; 624 if (task->thread.gsindex == GS_TLS_SEL) 625 base = read_32bit_tls(task, GS_TLS); 626 else if (doit) { 627 savesegment(gs, gsindex); 628 if (gsindex) 629 rdmsrl(MSR_KERNEL_GS_BASE, base); 630 else 631 base = task->thread.gs; 632 } else 633 base = task->thread.gs; 634 ret = put_user(base, (unsigned long __user *)addr); 635 break; 636 } 637 638 default: 639 ret = -EINVAL; 640 break; 641 } 642 643 return ret; 644 } 645 646 long sys_arch_prctl(int code, unsigned long addr) 647 { 648 return do_arch_prctl(current, code, addr); 649 } 650 651 unsigned long KSTK_ESP(struct task_struct *task) 652 { 653 return (test_tsk_thread_flag(task, TIF_IA32)) ? 654 (task_pt_regs(task)->sp) : ((task)->thread.usersp); 655 } 656