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