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/cpu.h> 18 #include <linux/errno.h> 19 #include <linux/sched.h> 20 #include <linux/fs.h> 21 #include <linux/kernel.h> 22 #include <linux/mm.h> 23 #include <linux/elfcore.h> 24 #include <linux/smp.h> 25 #include <linux/slab.h> 26 #include <linux/user.h> 27 #include <linux/interrupt.h> 28 #include <linux/delay.h> 29 #include <linux/module.h> 30 #include <linux/ptrace.h> 31 #include <linux/notifier.h> 32 #include <linux/kprobes.h> 33 #include <linux/kdebug.h> 34 #include <linux/prctl.h> 35 #include <linux/uaccess.h> 36 #include <linux/io.h> 37 #include <linux/ftrace.h> 38 39 #include <asm/pgtable.h> 40 #include <asm/processor.h> 41 #include <asm/i387.h> 42 #include <asm/fpu-internal.h> 43 #include <asm/mmu_context.h> 44 #include <asm/prctl.h> 45 #include <asm/desc.h> 46 #include <asm/proto.h> 47 #include <asm/ia32.h> 48 #include <asm/idle.h> 49 #include <asm/syscalls.h> 50 #include <asm/debugreg.h> 51 #include <asm/switch_to.h> 52 53 asmlinkage extern void ret_from_fork(void); 54 55 DEFINE_PER_CPU(unsigned long, old_rsp); 56 57 /* Prints also some state that isn't saved in the pt_regs */ 58 void __show_regs(struct pt_regs *regs, int all) 59 { 60 unsigned long cr0 = 0L, cr2 = 0L, cr3 = 0L, cr4 = 0L, fs, gs, shadowgs; 61 unsigned long d0, d1, d2, d3, d6, d7; 62 unsigned int fsindex, gsindex; 63 unsigned int ds, cs, es; 64 65 show_regs_common(); 66 printk(KERN_DEFAULT "RIP: %04lx:[<%016lx>] ", regs->cs & 0xffff, regs->ip); 67 printk_address(regs->ip, 1); 68 printk(KERN_DEFAULT "RSP: %04lx:%016lx EFLAGS: %08lx\n", regs->ss, 69 regs->sp, regs->flags); 70 printk(KERN_DEFAULT "RAX: %016lx RBX: %016lx RCX: %016lx\n", 71 regs->ax, regs->bx, regs->cx); 72 printk(KERN_DEFAULT "RDX: %016lx RSI: %016lx RDI: %016lx\n", 73 regs->dx, regs->si, regs->di); 74 printk(KERN_DEFAULT "RBP: %016lx R08: %016lx R09: %016lx\n", 75 regs->bp, regs->r8, regs->r9); 76 printk(KERN_DEFAULT "R10: %016lx R11: %016lx R12: %016lx\n", 77 regs->r10, regs->r11, regs->r12); 78 printk(KERN_DEFAULT "R13: %016lx R14: %016lx R15: %016lx\n", 79 regs->r13, regs->r14, regs->r15); 80 81 asm("movl %%ds,%0" : "=r" (ds)); 82 asm("movl %%cs,%0" : "=r" (cs)); 83 asm("movl %%es,%0" : "=r" (es)); 84 asm("movl %%fs,%0" : "=r" (fsindex)); 85 asm("movl %%gs,%0" : "=r" (gsindex)); 86 87 rdmsrl(MSR_FS_BASE, fs); 88 rdmsrl(MSR_GS_BASE, gs); 89 rdmsrl(MSR_KERNEL_GS_BASE, shadowgs); 90 91 if (!all) 92 return; 93 94 cr0 = read_cr0(); 95 cr2 = read_cr2(); 96 cr3 = read_cr3(); 97 cr4 = read_cr4(); 98 99 printk(KERN_DEFAULT "FS: %016lx(%04x) GS:%016lx(%04x) knlGS:%016lx\n", 100 fs, fsindex, gs, gsindex, shadowgs); 101 printk(KERN_DEFAULT "CS: %04x DS: %04x ES: %04x CR0: %016lx\n", cs, ds, 102 es, cr0); 103 printk(KERN_DEFAULT "CR2: %016lx CR3: %016lx CR4: %016lx\n", cr2, cr3, 104 cr4); 105 106 get_debugreg(d0, 0); 107 get_debugreg(d1, 1); 108 get_debugreg(d2, 2); 109 printk(KERN_DEFAULT "DR0: %016lx DR1: %016lx DR2: %016lx\n", d0, d1, d2); 110 get_debugreg(d3, 3); 111 get_debugreg(d6, 6); 112 get_debugreg(d7, 7); 113 printk(KERN_DEFAULT "DR3: %016lx DR6: %016lx DR7: %016lx\n", d3, d6, d7); 114 } 115 116 void release_thread(struct task_struct *dead_task) 117 { 118 if (dead_task->mm) { 119 if (dead_task->mm->context.size) { 120 printk("WARNING: dead process %8s still has LDT? <%p/%d>\n", 121 dead_task->comm, 122 dead_task->mm->context.ldt, 123 dead_task->mm->context.size); 124 BUG(); 125 } 126 } 127 } 128 129 static inline void set_32bit_tls(struct task_struct *t, int tls, u32 addr) 130 { 131 struct user_desc ud = { 132 .base_addr = addr, 133 .limit = 0xfffff, 134 .seg_32bit = 1, 135 .limit_in_pages = 1, 136 .useable = 1, 137 }; 138 struct desc_struct *desc = t->thread.tls_array; 139 desc += tls; 140 fill_ldt(desc, &ud); 141 } 142 143 static inline u32 read_32bit_tls(struct task_struct *t, int tls) 144 { 145 return get_desc_base(&t->thread.tls_array[tls]); 146 } 147 148 /* 149 * This gets called before we allocate a new thread and copy 150 * the current task into it. 151 */ 152 void prepare_to_copy(struct task_struct *tsk) 153 { 154 unlazy_fpu(tsk); 155 } 156 157 int copy_thread(unsigned long clone_flags, unsigned long sp, 158 unsigned long unused, 159 struct task_struct *p, struct pt_regs *regs) 160 { 161 int err; 162 struct pt_regs *childregs; 163 struct task_struct *me = current; 164 165 childregs = ((struct pt_regs *) 166 (THREAD_SIZE + task_stack_page(p))) - 1; 167 *childregs = *regs; 168 169 childregs->ax = 0; 170 if (user_mode(regs)) 171 childregs->sp = sp; 172 else 173 childregs->sp = (unsigned long)childregs; 174 175 p->thread.sp = (unsigned long) childregs; 176 p->thread.sp0 = (unsigned long) (childregs+1); 177 p->thread.usersp = me->thread.usersp; 178 179 set_tsk_thread_flag(p, TIF_FORK); 180 181 p->fpu_counter = 0; 182 p->thread.io_bitmap_ptr = NULL; 183 184 savesegment(gs, p->thread.gsindex); 185 p->thread.gs = p->thread.gsindex ? 0 : me->thread.gs; 186 savesegment(fs, p->thread.fsindex); 187 p->thread.fs = p->thread.fsindex ? 0 : me->thread.fs; 188 savesegment(es, p->thread.es); 189 savesegment(ds, p->thread.ds); 190 191 err = -ENOMEM; 192 memset(p->thread.ptrace_bps, 0, sizeof(p->thread.ptrace_bps)); 193 194 if (unlikely(test_tsk_thread_flag(me, TIF_IO_BITMAP))) { 195 p->thread.io_bitmap_ptr = kmemdup(me->thread.io_bitmap_ptr, 196 IO_BITMAP_BYTES, GFP_KERNEL); 197 if (!p->thread.io_bitmap_ptr) { 198 p->thread.io_bitmap_max = 0; 199 return -ENOMEM; 200 } 201 set_tsk_thread_flag(p, TIF_IO_BITMAP); 202 } 203 204 /* 205 * Set a new TLS for the child thread? 206 */ 207 if (clone_flags & CLONE_SETTLS) { 208 #ifdef CONFIG_IA32_EMULATION 209 if (test_thread_flag(TIF_IA32)) 210 err = do_set_thread_area(p, -1, 211 (struct user_desc __user *)childregs->si, 0); 212 else 213 #endif 214 err = do_arch_prctl(p, ARCH_SET_FS, childregs->r8); 215 if (err) 216 goto out; 217 } 218 err = 0; 219 out: 220 if (err && p->thread.io_bitmap_ptr) { 221 kfree(p->thread.io_bitmap_ptr); 222 p->thread.io_bitmap_max = 0; 223 } 224 225 return err; 226 } 227 228 static void 229 start_thread_common(struct pt_regs *regs, unsigned long new_ip, 230 unsigned long new_sp, 231 unsigned int _cs, unsigned int _ss, unsigned int _ds) 232 { 233 loadsegment(fs, 0); 234 loadsegment(es, _ds); 235 loadsegment(ds, _ds); 236 load_gs_index(0); 237 current->thread.usersp = new_sp; 238 regs->ip = new_ip; 239 regs->sp = new_sp; 240 percpu_write(old_rsp, new_sp); 241 regs->cs = _cs; 242 regs->ss = _ss; 243 regs->flags = X86_EFLAGS_IF; 244 /* 245 * Free the old FP and other extended state 246 */ 247 free_thread_xstate(current); 248 } 249 250 void 251 start_thread(struct pt_regs *regs, unsigned long new_ip, unsigned long new_sp) 252 { 253 start_thread_common(regs, new_ip, new_sp, 254 __USER_CS, __USER_DS, 0); 255 } 256 257 #ifdef CONFIG_IA32_EMULATION 258 void start_thread_ia32(struct pt_regs *regs, u32 new_ip, u32 new_sp) 259 { 260 start_thread_common(regs, new_ip, new_sp, 261 test_thread_flag(TIF_X32) 262 ? __USER_CS : __USER32_CS, 263 __USER_DS, __USER_DS); 264 } 265 #endif 266 267 /* 268 * switch_to(x,y) should switch tasks from x to y. 269 * 270 * This could still be optimized: 271 * - fold all the options into a flag word and test it with a single test. 272 * - could test fs/gs bitsliced 273 * 274 * Kprobes not supported here. Set the probe on schedule instead. 275 * Function graph tracer not supported too. 276 */ 277 __notrace_funcgraph struct task_struct * 278 __switch_to(struct task_struct *prev_p, struct task_struct *next_p) 279 { 280 struct thread_struct *prev = &prev_p->thread; 281 struct thread_struct *next = &next_p->thread; 282 int cpu = smp_processor_id(); 283 struct tss_struct *tss = &per_cpu(init_tss, cpu); 284 unsigned fsindex, gsindex; 285 fpu_switch_t fpu; 286 287 fpu = switch_fpu_prepare(prev_p, next_p, cpu); 288 289 /* 290 * Reload esp0, LDT and the page table pointer: 291 */ 292 load_sp0(tss, next); 293 294 /* 295 * Switch DS and ES. 296 * This won't pick up thread selector changes, but I guess that is ok. 297 */ 298 savesegment(es, prev->es); 299 if (unlikely(next->es | prev->es)) 300 loadsegment(es, next->es); 301 302 savesegment(ds, prev->ds); 303 if (unlikely(next->ds | prev->ds)) 304 loadsegment(ds, next->ds); 305 306 307 /* We must save %fs and %gs before load_TLS() because 308 * %fs and %gs may be cleared by load_TLS(). 309 * 310 * (e.g. xen_load_tls()) 311 */ 312 savesegment(fs, fsindex); 313 savesegment(gs, gsindex); 314 315 load_TLS(next, cpu); 316 317 /* 318 * Leave lazy mode, flushing any hypercalls made here. 319 * This must be done before restoring TLS segments so 320 * the GDT and LDT are properly updated, and must be 321 * done before math_state_restore, so the TS bit is up 322 * to date. 323 */ 324 arch_end_context_switch(next_p); 325 326 /* 327 * Switch FS and GS. 328 * 329 * Segment register != 0 always requires a reload. Also 330 * reload when it has changed. When prev process used 64bit 331 * base always reload to avoid an information leak. 332 */ 333 if (unlikely(fsindex | next->fsindex | prev->fs)) { 334 loadsegment(fs, next->fsindex); 335 /* 336 * Check if the user used a selector != 0; if yes 337 * clear 64bit base, since overloaded base is always 338 * mapped to the Null selector 339 */ 340 if (fsindex) 341 prev->fs = 0; 342 } 343 /* when next process has a 64bit base use it */ 344 if (next->fs) 345 wrmsrl(MSR_FS_BASE, next->fs); 346 prev->fsindex = fsindex; 347 348 if (unlikely(gsindex | next->gsindex | prev->gs)) { 349 load_gs_index(next->gsindex); 350 if (gsindex) 351 prev->gs = 0; 352 } 353 if (next->gs) 354 wrmsrl(MSR_KERNEL_GS_BASE, next->gs); 355 prev->gsindex = gsindex; 356 357 switch_fpu_finish(next_p, fpu); 358 359 /* 360 * Switch the PDA and FPU contexts. 361 */ 362 prev->usersp = percpu_read(old_rsp); 363 percpu_write(old_rsp, next->usersp); 364 percpu_write(current_task, next_p); 365 366 percpu_write(kernel_stack, 367 (unsigned long)task_stack_page(next_p) + 368 THREAD_SIZE - KERNEL_STACK_OFFSET); 369 370 /* 371 * Now maybe reload the debug registers and handle I/O bitmaps 372 */ 373 if (unlikely(task_thread_info(next_p)->flags & _TIF_WORK_CTXSW_NEXT || 374 task_thread_info(prev_p)->flags & _TIF_WORK_CTXSW_PREV)) 375 __switch_to_xtra(prev_p, next_p, tss); 376 377 return prev_p; 378 } 379 380 void set_personality_64bit(void) 381 { 382 /* inherit personality from parent */ 383 384 /* Make sure to be in 64bit mode */ 385 clear_thread_flag(TIF_IA32); 386 clear_thread_flag(TIF_ADDR32); 387 clear_thread_flag(TIF_X32); 388 389 /* Ensure the corresponding mm is not marked. */ 390 if (current->mm) 391 current->mm->context.ia32_compat = 0; 392 393 /* TBD: overwrites user setup. Should have two bits. 394 But 64bit processes have always behaved this way, 395 so it's not too bad. The main problem is just that 396 32bit childs are affected again. */ 397 current->personality &= ~READ_IMPLIES_EXEC; 398 } 399 400 void set_personality_ia32(bool x32) 401 { 402 /* inherit personality from parent */ 403 404 /* Make sure to be in 32bit mode */ 405 set_thread_flag(TIF_ADDR32); 406 407 /* Mark the associated mm as containing 32-bit tasks. */ 408 if (current->mm) 409 current->mm->context.ia32_compat = 1; 410 411 if (x32) { 412 clear_thread_flag(TIF_IA32); 413 set_thread_flag(TIF_X32); 414 current->personality &= ~READ_IMPLIES_EXEC; 415 /* is_compat_task() uses the presence of the x32 416 syscall bit flag to determine compat status */ 417 current_thread_info()->status &= ~TS_COMPAT; 418 } else { 419 set_thread_flag(TIF_IA32); 420 clear_thread_flag(TIF_X32); 421 current->personality |= force_personality32; 422 /* Prepare the first "return" to user space */ 423 current_thread_info()->status |= TS_COMPAT; 424 } 425 } 426 427 unsigned long get_wchan(struct task_struct *p) 428 { 429 unsigned long stack; 430 u64 fp, ip; 431 int count = 0; 432 433 if (!p || p == current || p->state == TASK_RUNNING) 434 return 0; 435 stack = (unsigned long)task_stack_page(p); 436 if (p->thread.sp < stack || p->thread.sp >= stack+THREAD_SIZE) 437 return 0; 438 fp = *(u64 *)(p->thread.sp); 439 do { 440 if (fp < (unsigned long)stack || 441 fp >= (unsigned long)stack+THREAD_SIZE) 442 return 0; 443 ip = *(u64 *)(fp+8); 444 if (!in_sched_functions(ip)) 445 return ip; 446 fp = *(u64 *)fp; 447 } while (count++ < 16); 448 return 0; 449 } 450 451 long do_arch_prctl(struct task_struct *task, int code, unsigned long addr) 452 { 453 int ret = 0; 454 int doit = task == current; 455 int cpu; 456 457 switch (code) { 458 case ARCH_SET_GS: 459 if (addr >= TASK_SIZE_OF(task)) 460 return -EPERM; 461 cpu = get_cpu(); 462 /* handle small bases via the GDT because that's faster to 463 switch. */ 464 if (addr <= 0xffffffff) { 465 set_32bit_tls(task, GS_TLS, addr); 466 if (doit) { 467 load_TLS(&task->thread, cpu); 468 load_gs_index(GS_TLS_SEL); 469 } 470 task->thread.gsindex = GS_TLS_SEL; 471 task->thread.gs = 0; 472 } else { 473 task->thread.gsindex = 0; 474 task->thread.gs = addr; 475 if (doit) { 476 load_gs_index(0); 477 ret = checking_wrmsrl(MSR_KERNEL_GS_BASE, addr); 478 } 479 } 480 put_cpu(); 481 break; 482 case ARCH_SET_FS: 483 /* Not strictly needed for fs, but do it for symmetry 484 with gs */ 485 if (addr >= TASK_SIZE_OF(task)) 486 return -EPERM; 487 cpu = get_cpu(); 488 /* handle small bases via the GDT because that's faster to 489 switch. */ 490 if (addr <= 0xffffffff) { 491 set_32bit_tls(task, FS_TLS, addr); 492 if (doit) { 493 load_TLS(&task->thread, cpu); 494 loadsegment(fs, FS_TLS_SEL); 495 } 496 task->thread.fsindex = FS_TLS_SEL; 497 task->thread.fs = 0; 498 } else { 499 task->thread.fsindex = 0; 500 task->thread.fs = addr; 501 if (doit) { 502 /* set the selector to 0 to not confuse 503 __switch_to */ 504 loadsegment(fs, 0); 505 ret = checking_wrmsrl(MSR_FS_BASE, addr); 506 } 507 } 508 put_cpu(); 509 break; 510 case ARCH_GET_FS: { 511 unsigned long base; 512 if (task->thread.fsindex == FS_TLS_SEL) 513 base = read_32bit_tls(task, FS_TLS); 514 else if (doit) 515 rdmsrl(MSR_FS_BASE, base); 516 else 517 base = task->thread.fs; 518 ret = put_user(base, (unsigned long __user *)addr); 519 break; 520 } 521 case ARCH_GET_GS: { 522 unsigned long base; 523 unsigned gsindex; 524 if (task->thread.gsindex == GS_TLS_SEL) 525 base = read_32bit_tls(task, GS_TLS); 526 else if (doit) { 527 savesegment(gs, gsindex); 528 if (gsindex) 529 rdmsrl(MSR_KERNEL_GS_BASE, base); 530 else 531 base = task->thread.gs; 532 } else 533 base = task->thread.gs; 534 ret = put_user(base, (unsigned long __user *)addr); 535 break; 536 } 537 538 default: 539 ret = -EINVAL; 540 break; 541 } 542 543 return ret; 544 } 545 546 long sys_arch_prctl(int code, unsigned long addr) 547 { 548 return do_arch_prctl(current, code, addr); 549 } 550 551 unsigned long KSTK_ESP(struct task_struct *task) 552 { 553 return (test_tsk_thread_flag(task, TIF_IA32)) ? 554 (task_pt_regs(task)->sp) : ((task)->thread.usersp); 555 } 556