1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Copyright (C) 1995 Linus Torvalds 4 * 5 * Pentium III FXSR, SSE support 6 * Gareth Hughes <gareth@valinux.com>, May 2000 7 * 8 * X86-64 port 9 * Andi Kleen. 10 * 11 * CPU hotplug support - ashok.raj@intel.com 12 */ 13 14 /* 15 * This file handles the architecture-dependent parts of process handling.. 16 */ 17 18 #include <linux/cpu.h> 19 #include <linux/errno.h> 20 #include <linux/sched.h> 21 #include <linux/sched/task.h> 22 #include <linux/sched/task_stack.h> 23 #include <linux/fs.h> 24 #include <linux/kernel.h> 25 #include <linux/mm.h> 26 #include <linux/elfcore.h> 27 #include <linux/smp.h> 28 #include <linux/slab.h> 29 #include <linux/user.h> 30 #include <linux/interrupt.h> 31 #include <linux/delay.h> 32 #include <linux/export.h> 33 #include <linux/ptrace.h> 34 #include <linux/notifier.h> 35 #include <linux/kprobes.h> 36 #include <linux/kdebug.h> 37 #include <linux/prctl.h> 38 #include <linux/uaccess.h> 39 #include <linux/io.h> 40 #include <linux/ftrace.h> 41 #include <linux/syscalls.h> 42 43 #include <asm/processor.h> 44 #include <asm/pkru.h> 45 #include <asm/fpu/internal.h> 46 #include <asm/mmu_context.h> 47 #include <asm/prctl.h> 48 #include <asm/desc.h> 49 #include <asm/proto.h> 50 #include <asm/ia32.h> 51 #include <asm/debugreg.h> 52 #include <asm/switch_to.h> 53 #include <asm/xen/hypervisor.h> 54 #include <asm/vdso.h> 55 #include <asm/resctrl.h> 56 #include <asm/unistd.h> 57 #include <asm/fsgsbase.h> 58 #ifdef CONFIG_IA32_EMULATION 59 /* Not included via unistd.h */ 60 #include <asm/unistd_32_ia32.h> 61 #endif 62 63 #include "process.h" 64 65 /* Prints also some state that isn't saved in the pt_regs */ 66 void __show_regs(struct pt_regs *regs, enum show_regs_mode mode, 67 const char *log_lvl) 68 { 69 unsigned long cr0 = 0L, cr2 = 0L, cr3 = 0L, cr4 = 0L, fs, gs, shadowgs; 70 unsigned long d0, d1, d2, d3, d6, d7; 71 unsigned int fsindex, gsindex; 72 unsigned int ds, es; 73 74 show_iret_regs(regs, log_lvl); 75 76 if (regs->orig_ax != -1) 77 pr_cont(" ORIG_RAX: %016lx\n", regs->orig_ax); 78 else 79 pr_cont("\n"); 80 81 printk("%sRAX: %016lx RBX: %016lx RCX: %016lx\n", 82 log_lvl, regs->ax, regs->bx, regs->cx); 83 printk("%sRDX: %016lx RSI: %016lx RDI: %016lx\n", 84 log_lvl, regs->dx, regs->si, regs->di); 85 printk("%sRBP: %016lx R08: %016lx R09: %016lx\n", 86 log_lvl, regs->bp, regs->r8, regs->r9); 87 printk("%sR10: %016lx R11: %016lx R12: %016lx\n", 88 log_lvl, regs->r10, regs->r11, regs->r12); 89 printk("%sR13: %016lx R14: %016lx R15: %016lx\n", 90 log_lvl, regs->r13, regs->r14, regs->r15); 91 92 if (mode == SHOW_REGS_SHORT) 93 return; 94 95 if (mode == SHOW_REGS_USER) { 96 rdmsrl(MSR_FS_BASE, fs); 97 rdmsrl(MSR_KERNEL_GS_BASE, shadowgs); 98 printk("%sFS: %016lx GS: %016lx\n", 99 log_lvl, fs, shadowgs); 100 return; 101 } 102 103 asm("movl %%ds,%0" : "=r" (ds)); 104 asm("movl %%es,%0" : "=r" (es)); 105 asm("movl %%fs,%0" : "=r" (fsindex)); 106 asm("movl %%gs,%0" : "=r" (gsindex)); 107 108 rdmsrl(MSR_FS_BASE, fs); 109 rdmsrl(MSR_GS_BASE, gs); 110 rdmsrl(MSR_KERNEL_GS_BASE, shadowgs); 111 112 cr0 = read_cr0(); 113 cr2 = read_cr2(); 114 cr3 = __read_cr3(); 115 cr4 = __read_cr4(); 116 117 printk("%sFS: %016lx(%04x) GS:%016lx(%04x) knlGS:%016lx\n", 118 log_lvl, fs, fsindex, gs, gsindex, shadowgs); 119 printk("%sCS: %04lx DS: %04x ES: %04x CR0: %016lx\n", 120 log_lvl, regs->cs, ds, es, cr0); 121 printk("%sCR2: %016lx CR3: %016lx CR4: %016lx\n", 122 log_lvl, cr2, cr3, cr4); 123 124 get_debugreg(d0, 0); 125 get_debugreg(d1, 1); 126 get_debugreg(d2, 2); 127 get_debugreg(d3, 3); 128 get_debugreg(d6, 6); 129 get_debugreg(d7, 7); 130 131 /* Only print out debug registers if they are in their non-default state. */ 132 if (!((d0 == 0) && (d1 == 0) && (d2 == 0) && (d3 == 0) && 133 (d6 == DR6_RESERVED) && (d7 == 0x400))) { 134 printk("%sDR0: %016lx DR1: %016lx DR2: %016lx\n", 135 log_lvl, d0, d1, d2); 136 printk("%sDR3: %016lx DR6: %016lx DR7: %016lx\n", 137 log_lvl, d3, d6, d7); 138 } 139 140 if (cpu_feature_enabled(X86_FEATURE_OSPKE)) 141 printk("%sPKRU: %08x\n", log_lvl, read_pkru()); 142 } 143 144 void release_thread(struct task_struct *dead_task) 145 { 146 WARN_ON(dead_task->mm); 147 } 148 149 enum which_selector { 150 FS, 151 GS 152 }; 153 154 /* 155 * Out of line to be protected from kprobes and tracing. If this would be 156 * traced or probed than any access to a per CPU variable happens with 157 * the wrong GS. 158 * 159 * It is not used on Xen paravirt. When paravirt support is needed, it 160 * needs to be renamed with native_ prefix. 161 */ 162 static noinstr unsigned long __rdgsbase_inactive(void) 163 { 164 unsigned long gsbase; 165 166 lockdep_assert_irqs_disabled(); 167 168 if (!static_cpu_has(X86_FEATURE_XENPV)) { 169 native_swapgs(); 170 gsbase = rdgsbase(); 171 native_swapgs(); 172 } else { 173 instrumentation_begin(); 174 rdmsrl(MSR_KERNEL_GS_BASE, gsbase); 175 instrumentation_end(); 176 } 177 178 return gsbase; 179 } 180 181 /* 182 * Out of line to be protected from kprobes and tracing. If this would be 183 * traced or probed than any access to a per CPU variable happens with 184 * the wrong GS. 185 * 186 * It is not used on Xen paravirt. When paravirt support is needed, it 187 * needs to be renamed with native_ prefix. 188 */ 189 static noinstr void __wrgsbase_inactive(unsigned long gsbase) 190 { 191 lockdep_assert_irqs_disabled(); 192 193 if (!static_cpu_has(X86_FEATURE_XENPV)) { 194 native_swapgs(); 195 wrgsbase(gsbase); 196 native_swapgs(); 197 } else { 198 instrumentation_begin(); 199 wrmsrl(MSR_KERNEL_GS_BASE, gsbase); 200 instrumentation_end(); 201 } 202 } 203 204 /* 205 * Saves the FS or GS base for an outgoing thread if FSGSBASE extensions are 206 * not available. The goal is to be reasonably fast on non-FSGSBASE systems. 207 * It's forcibly inlined because it'll generate better code and this function 208 * is hot. 209 */ 210 static __always_inline void save_base_legacy(struct task_struct *prev_p, 211 unsigned short selector, 212 enum which_selector which) 213 { 214 if (likely(selector == 0)) { 215 /* 216 * On Intel (without X86_BUG_NULL_SEG), the segment base could 217 * be the pre-existing saved base or it could be zero. On AMD 218 * (with X86_BUG_NULL_SEG), the segment base could be almost 219 * anything. 220 * 221 * This branch is very hot (it's hit twice on almost every 222 * context switch between 64-bit programs), and avoiding 223 * the RDMSR helps a lot, so we just assume that whatever 224 * value is already saved is correct. This matches historical 225 * Linux behavior, so it won't break existing applications. 226 * 227 * To avoid leaking state, on non-X86_BUG_NULL_SEG CPUs, if we 228 * report that the base is zero, it needs to actually be zero: 229 * see the corresponding logic in load_seg_legacy. 230 */ 231 } else { 232 /* 233 * If the selector is 1, 2, or 3, then the base is zero on 234 * !X86_BUG_NULL_SEG CPUs and could be anything on 235 * X86_BUG_NULL_SEG CPUs. In the latter case, Linux 236 * has never attempted to preserve the base across context 237 * switches. 238 * 239 * If selector > 3, then it refers to a real segment, and 240 * saving the base isn't necessary. 241 */ 242 if (which == FS) 243 prev_p->thread.fsbase = 0; 244 else 245 prev_p->thread.gsbase = 0; 246 } 247 } 248 249 static __always_inline void save_fsgs(struct task_struct *task) 250 { 251 savesegment(fs, task->thread.fsindex); 252 savesegment(gs, task->thread.gsindex); 253 if (static_cpu_has(X86_FEATURE_FSGSBASE)) { 254 /* 255 * If FSGSBASE is enabled, we can't make any useful guesses 256 * about the base, and user code expects us to save the current 257 * value. Fortunately, reading the base directly is efficient. 258 */ 259 task->thread.fsbase = rdfsbase(); 260 task->thread.gsbase = __rdgsbase_inactive(); 261 } else { 262 save_base_legacy(task, task->thread.fsindex, FS); 263 save_base_legacy(task, task->thread.gsindex, GS); 264 } 265 } 266 267 /* 268 * While a process is running,current->thread.fsbase and current->thread.gsbase 269 * may not match the corresponding CPU registers (see save_base_legacy()). 270 */ 271 void current_save_fsgs(void) 272 { 273 unsigned long flags; 274 275 /* Interrupts need to be off for FSGSBASE */ 276 local_irq_save(flags); 277 save_fsgs(current); 278 local_irq_restore(flags); 279 } 280 #if IS_ENABLED(CONFIG_KVM) 281 EXPORT_SYMBOL_GPL(current_save_fsgs); 282 #endif 283 284 static __always_inline void loadseg(enum which_selector which, 285 unsigned short sel) 286 { 287 if (which == FS) 288 loadsegment(fs, sel); 289 else 290 load_gs_index(sel); 291 } 292 293 static __always_inline void load_seg_legacy(unsigned short prev_index, 294 unsigned long prev_base, 295 unsigned short next_index, 296 unsigned long next_base, 297 enum which_selector which) 298 { 299 if (likely(next_index <= 3)) { 300 /* 301 * The next task is using 64-bit TLS, is not using this 302 * segment at all, or is having fun with arcane CPU features. 303 */ 304 if (next_base == 0) { 305 /* 306 * Nasty case: on AMD CPUs, we need to forcibly zero 307 * the base. 308 */ 309 if (static_cpu_has_bug(X86_BUG_NULL_SEG)) { 310 loadseg(which, __USER_DS); 311 loadseg(which, next_index); 312 } else { 313 /* 314 * We could try to exhaustively detect cases 315 * under which we can skip the segment load, 316 * but there's really only one case that matters 317 * for performance: if both the previous and 318 * next states are fully zeroed, we can skip 319 * the load. 320 * 321 * (This assumes that prev_base == 0 has no 322 * false positives. This is the case on 323 * Intel-style CPUs.) 324 */ 325 if (likely(prev_index | next_index | prev_base)) 326 loadseg(which, next_index); 327 } 328 } else { 329 if (prev_index != next_index) 330 loadseg(which, next_index); 331 wrmsrl(which == FS ? MSR_FS_BASE : MSR_KERNEL_GS_BASE, 332 next_base); 333 } 334 } else { 335 /* 336 * The next task is using a real segment. Loading the selector 337 * is sufficient. 338 */ 339 loadseg(which, next_index); 340 } 341 } 342 343 /* 344 * Store prev's PKRU value and load next's PKRU value if they differ. PKRU 345 * is not XSTATE managed on context switch because that would require a 346 * lookup in the task's FPU xsave buffer and require to keep that updated 347 * in various places. 348 */ 349 static __always_inline void x86_pkru_load(struct thread_struct *prev, 350 struct thread_struct *next) 351 { 352 if (!cpu_feature_enabled(X86_FEATURE_OSPKE)) 353 return; 354 355 /* Stash the prev task's value: */ 356 prev->pkru = rdpkru(); 357 358 /* 359 * PKRU writes are slightly expensive. Avoid them when not 360 * strictly necessary: 361 */ 362 if (prev->pkru != next->pkru) 363 wrpkru(next->pkru); 364 } 365 366 static __always_inline void x86_fsgsbase_load(struct thread_struct *prev, 367 struct thread_struct *next) 368 { 369 if (static_cpu_has(X86_FEATURE_FSGSBASE)) { 370 /* Update the FS and GS selectors if they could have changed. */ 371 if (unlikely(prev->fsindex || next->fsindex)) 372 loadseg(FS, next->fsindex); 373 if (unlikely(prev->gsindex || next->gsindex)) 374 loadseg(GS, next->gsindex); 375 376 /* Update the bases. */ 377 wrfsbase(next->fsbase); 378 __wrgsbase_inactive(next->gsbase); 379 } else { 380 load_seg_legacy(prev->fsindex, prev->fsbase, 381 next->fsindex, next->fsbase, FS); 382 load_seg_legacy(prev->gsindex, prev->gsbase, 383 next->gsindex, next->gsbase, GS); 384 } 385 } 386 387 unsigned long x86_fsgsbase_read_task(struct task_struct *task, 388 unsigned short selector) 389 { 390 unsigned short idx = selector >> 3; 391 unsigned long base; 392 393 if (likely((selector & SEGMENT_TI_MASK) == 0)) { 394 if (unlikely(idx >= GDT_ENTRIES)) 395 return 0; 396 397 /* 398 * There are no user segments in the GDT with nonzero bases 399 * other than the TLS segments. 400 */ 401 if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX) 402 return 0; 403 404 idx -= GDT_ENTRY_TLS_MIN; 405 base = get_desc_base(&task->thread.tls_array[idx]); 406 } else { 407 #ifdef CONFIG_MODIFY_LDT_SYSCALL 408 struct ldt_struct *ldt; 409 410 /* 411 * If performance here mattered, we could protect the LDT 412 * with RCU. This is a slow path, though, so we can just 413 * take the mutex. 414 */ 415 mutex_lock(&task->mm->context.lock); 416 ldt = task->mm->context.ldt; 417 if (unlikely(!ldt || idx >= ldt->nr_entries)) 418 base = 0; 419 else 420 base = get_desc_base(ldt->entries + idx); 421 mutex_unlock(&task->mm->context.lock); 422 #else 423 base = 0; 424 #endif 425 } 426 427 return base; 428 } 429 430 unsigned long x86_gsbase_read_cpu_inactive(void) 431 { 432 unsigned long gsbase; 433 434 if (boot_cpu_has(X86_FEATURE_FSGSBASE)) { 435 unsigned long flags; 436 437 local_irq_save(flags); 438 gsbase = __rdgsbase_inactive(); 439 local_irq_restore(flags); 440 } else { 441 rdmsrl(MSR_KERNEL_GS_BASE, gsbase); 442 } 443 444 return gsbase; 445 } 446 447 void x86_gsbase_write_cpu_inactive(unsigned long gsbase) 448 { 449 if (boot_cpu_has(X86_FEATURE_FSGSBASE)) { 450 unsigned long flags; 451 452 local_irq_save(flags); 453 __wrgsbase_inactive(gsbase); 454 local_irq_restore(flags); 455 } else { 456 wrmsrl(MSR_KERNEL_GS_BASE, gsbase); 457 } 458 } 459 460 unsigned long x86_fsbase_read_task(struct task_struct *task) 461 { 462 unsigned long fsbase; 463 464 if (task == current) 465 fsbase = x86_fsbase_read_cpu(); 466 else if (boot_cpu_has(X86_FEATURE_FSGSBASE) || 467 (task->thread.fsindex == 0)) 468 fsbase = task->thread.fsbase; 469 else 470 fsbase = x86_fsgsbase_read_task(task, task->thread.fsindex); 471 472 return fsbase; 473 } 474 475 unsigned long x86_gsbase_read_task(struct task_struct *task) 476 { 477 unsigned long gsbase; 478 479 if (task == current) 480 gsbase = x86_gsbase_read_cpu_inactive(); 481 else if (boot_cpu_has(X86_FEATURE_FSGSBASE) || 482 (task->thread.gsindex == 0)) 483 gsbase = task->thread.gsbase; 484 else 485 gsbase = x86_fsgsbase_read_task(task, task->thread.gsindex); 486 487 return gsbase; 488 } 489 490 void x86_fsbase_write_task(struct task_struct *task, unsigned long fsbase) 491 { 492 WARN_ON_ONCE(task == current); 493 494 task->thread.fsbase = fsbase; 495 } 496 497 void x86_gsbase_write_task(struct task_struct *task, unsigned long gsbase) 498 { 499 WARN_ON_ONCE(task == current); 500 501 task->thread.gsbase = gsbase; 502 } 503 504 static void 505 start_thread_common(struct pt_regs *regs, unsigned long new_ip, 506 unsigned long new_sp, 507 unsigned int _cs, unsigned int _ss, unsigned int _ds) 508 { 509 WARN_ON_ONCE(regs != current_pt_regs()); 510 511 if (static_cpu_has(X86_BUG_NULL_SEG)) { 512 /* Loading zero below won't clear the base. */ 513 loadsegment(fs, __USER_DS); 514 load_gs_index(__USER_DS); 515 } 516 517 loadsegment(fs, 0); 518 loadsegment(es, _ds); 519 loadsegment(ds, _ds); 520 load_gs_index(0); 521 522 regs->ip = new_ip; 523 regs->sp = new_sp; 524 regs->cs = _cs; 525 regs->ss = _ss; 526 regs->flags = X86_EFLAGS_IF; 527 } 528 529 void 530 start_thread(struct pt_regs *regs, unsigned long new_ip, unsigned long new_sp) 531 { 532 start_thread_common(regs, new_ip, new_sp, 533 __USER_CS, __USER_DS, 0); 534 } 535 EXPORT_SYMBOL_GPL(start_thread); 536 537 #ifdef CONFIG_COMPAT 538 void compat_start_thread(struct pt_regs *regs, u32 new_ip, u32 new_sp, bool x32) 539 { 540 start_thread_common(regs, new_ip, new_sp, 541 x32 ? __USER_CS : __USER32_CS, 542 __USER_DS, __USER_DS); 543 } 544 #endif 545 546 /* 547 * switch_to(x,y) should switch tasks from x to y. 548 * 549 * This could still be optimized: 550 * - fold all the options into a flag word and test it with a single test. 551 * - could test fs/gs bitsliced 552 * 553 * Kprobes not supported here. Set the probe on schedule instead. 554 * Function graph tracer not supported too. 555 */ 556 __visible __notrace_funcgraph struct task_struct * 557 __switch_to(struct task_struct *prev_p, struct task_struct *next_p) 558 { 559 struct thread_struct *prev = &prev_p->thread; 560 struct thread_struct *next = &next_p->thread; 561 struct fpu *prev_fpu = &prev->fpu; 562 struct fpu *next_fpu = &next->fpu; 563 int cpu = smp_processor_id(); 564 565 WARN_ON_ONCE(IS_ENABLED(CONFIG_DEBUG_ENTRY) && 566 this_cpu_read(hardirq_stack_inuse)); 567 568 if (!test_thread_flag(TIF_NEED_FPU_LOAD)) 569 switch_fpu_prepare(prev_fpu, cpu); 570 571 /* We must save %fs and %gs before load_TLS() because 572 * %fs and %gs may be cleared by load_TLS(). 573 * 574 * (e.g. xen_load_tls()) 575 */ 576 save_fsgs(prev_p); 577 578 /* 579 * Load TLS before restoring any segments so that segment loads 580 * reference the correct GDT entries. 581 */ 582 load_TLS(next, cpu); 583 584 /* 585 * Leave lazy mode, flushing any hypercalls made here. This 586 * must be done after loading TLS entries in the GDT but before 587 * loading segments that might reference them. 588 */ 589 arch_end_context_switch(next_p); 590 591 /* Switch DS and ES. 592 * 593 * Reading them only returns the selectors, but writing them (if 594 * nonzero) loads the full descriptor from the GDT or LDT. The 595 * LDT for next is loaded in switch_mm, and the GDT is loaded 596 * above. 597 * 598 * We therefore need to write new values to the segment 599 * registers on every context switch unless both the new and old 600 * values are zero. 601 * 602 * Note that we don't need to do anything for CS and SS, as 603 * those are saved and restored as part of pt_regs. 604 */ 605 savesegment(es, prev->es); 606 if (unlikely(next->es | prev->es)) 607 loadsegment(es, next->es); 608 609 savesegment(ds, prev->ds); 610 if (unlikely(next->ds | prev->ds)) 611 loadsegment(ds, next->ds); 612 613 x86_fsgsbase_load(prev, next); 614 615 x86_pkru_load(prev, next); 616 617 /* 618 * Switch the PDA and FPU contexts. 619 */ 620 this_cpu_write(current_task, next_p); 621 this_cpu_write(cpu_current_top_of_stack, task_top_of_stack(next_p)); 622 623 switch_fpu_finish(next_fpu); 624 625 /* Reload sp0. */ 626 update_task_stack(next_p); 627 628 switch_to_extra(prev_p, next_p); 629 630 if (static_cpu_has_bug(X86_BUG_SYSRET_SS_ATTRS)) { 631 /* 632 * AMD CPUs have a misfeature: SYSRET sets the SS selector but 633 * does not update the cached descriptor. As a result, if we 634 * do SYSRET while SS is NULL, we'll end up in user mode with 635 * SS apparently equal to __USER_DS but actually unusable. 636 * 637 * The straightforward workaround would be to fix it up just 638 * before SYSRET, but that would slow down the system call 639 * fast paths. Instead, we ensure that SS is never NULL in 640 * system call context. We do this by replacing NULL SS 641 * selectors at every context switch. SYSCALL sets up a valid 642 * SS, so the only way to get NULL is to re-enter the kernel 643 * from CPL 3 through an interrupt. Since that can't happen 644 * in the same task as a running syscall, we are guaranteed to 645 * context switch between every interrupt vector entry and a 646 * subsequent SYSRET. 647 * 648 * We read SS first because SS reads are much faster than 649 * writes. Out of caution, we force SS to __KERNEL_DS even if 650 * it previously had a different non-NULL value. 651 */ 652 unsigned short ss_sel; 653 savesegment(ss, ss_sel); 654 if (ss_sel != __KERNEL_DS) 655 loadsegment(ss, __KERNEL_DS); 656 } 657 658 /* Load the Intel cache allocation PQR MSR. */ 659 resctrl_sched_in(); 660 661 return prev_p; 662 } 663 664 void set_personality_64bit(void) 665 { 666 /* inherit personality from parent */ 667 668 /* Make sure to be in 64bit mode */ 669 clear_thread_flag(TIF_ADDR32); 670 /* Pretend that this comes from a 64bit execve */ 671 task_pt_regs(current)->orig_ax = __NR_execve; 672 current_thread_info()->status &= ~TS_COMPAT; 673 if (current->mm) 674 current->mm->context.flags = MM_CONTEXT_HAS_VSYSCALL; 675 676 /* TBD: overwrites user setup. Should have two bits. 677 But 64bit processes have always behaved this way, 678 so it's not too bad. The main problem is just that 679 32bit children are affected again. */ 680 current->personality &= ~READ_IMPLIES_EXEC; 681 } 682 683 static void __set_personality_x32(void) 684 { 685 #ifdef CONFIG_X86_X32 686 if (current->mm) 687 current->mm->context.flags = 0; 688 689 current->personality &= ~READ_IMPLIES_EXEC; 690 /* 691 * in_32bit_syscall() uses the presence of the x32 syscall bit 692 * flag to determine compat status. The x86 mmap() code relies on 693 * the syscall bitness so set x32 syscall bit right here to make 694 * in_32bit_syscall() work during exec(). 695 * 696 * Pretend to come from a x32 execve. 697 */ 698 task_pt_regs(current)->orig_ax = __NR_x32_execve | __X32_SYSCALL_BIT; 699 current_thread_info()->status &= ~TS_COMPAT; 700 #endif 701 } 702 703 static void __set_personality_ia32(void) 704 { 705 #ifdef CONFIG_IA32_EMULATION 706 if (current->mm) { 707 /* 708 * uprobes applied to this MM need to know this and 709 * cannot use user_64bit_mode() at that time. 710 */ 711 current->mm->context.flags = MM_CONTEXT_UPROBE_IA32; 712 } 713 714 current->personality |= force_personality32; 715 /* Prepare the first "return" to user space */ 716 task_pt_regs(current)->orig_ax = __NR_ia32_execve; 717 current_thread_info()->status |= TS_COMPAT; 718 #endif 719 } 720 721 void set_personality_ia32(bool x32) 722 { 723 /* Make sure to be in 32bit mode */ 724 set_thread_flag(TIF_ADDR32); 725 726 if (x32) 727 __set_personality_x32(); 728 else 729 __set_personality_ia32(); 730 } 731 EXPORT_SYMBOL_GPL(set_personality_ia32); 732 733 #ifdef CONFIG_CHECKPOINT_RESTORE 734 static long prctl_map_vdso(const struct vdso_image *image, unsigned long addr) 735 { 736 int ret; 737 738 ret = map_vdso_once(image, addr); 739 if (ret) 740 return ret; 741 742 return (long)image->size; 743 } 744 #endif 745 746 long do_arch_prctl_64(struct task_struct *task, int option, unsigned long arg2) 747 { 748 int ret = 0; 749 750 switch (option) { 751 case ARCH_SET_GS: { 752 if (unlikely(arg2 >= TASK_SIZE_MAX)) 753 return -EPERM; 754 755 preempt_disable(); 756 /* 757 * ARCH_SET_GS has always overwritten the index 758 * and the base. Zero is the most sensible value 759 * to put in the index, and is the only value that 760 * makes any sense if FSGSBASE is unavailable. 761 */ 762 if (task == current) { 763 loadseg(GS, 0); 764 x86_gsbase_write_cpu_inactive(arg2); 765 766 /* 767 * On non-FSGSBASE systems, save_base_legacy() expects 768 * that we also fill in thread.gsbase. 769 */ 770 task->thread.gsbase = arg2; 771 772 } else { 773 task->thread.gsindex = 0; 774 x86_gsbase_write_task(task, arg2); 775 } 776 preempt_enable(); 777 break; 778 } 779 case ARCH_SET_FS: { 780 /* 781 * Not strictly needed for %fs, but do it for symmetry 782 * with %gs 783 */ 784 if (unlikely(arg2 >= TASK_SIZE_MAX)) 785 return -EPERM; 786 787 preempt_disable(); 788 /* 789 * Set the selector to 0 for the same reason 790 * as %gs above. 791 */ 792 if (task == current) { 793 loadseg(FS, 0); 794 x86_fsbase_write_cpu(arg2); 795 796 /* 797 * On non-FSGSBASE systems, save_base_legacy() expects 798 * that we also fill in thread.fsbase. 799 */ 800 task->thread.fsbase = arg2; 801 } else { 802 task->thread.fsindex = 0; 803 x86_fsbase_write_task(task, arg2); 804 } 805 preempt_enable(); 806 break; 807 } 808 case ARCH_GET_FS: { 809 unsigned long base = x86_fsbase_read_task(task); 810 811 ret = put_user(base, (unsigned long __user *)arg2); 812 break; 813 } 814 case ARCH_GET_GS: { 815 unsigned long base = x86_gsbase_read_task(task); 816 817 ret = put_user(base, (unsigned long __user *)arg2); 818 break; 819 } 820 821 #ifdef CONFIG_CHECKPOINT_RESTORE 822 # ifdef CONFIG_X86_X32_ABI 823 case ARCH_MAP_VDSO_X32: 824 return prctl_map_vdso(&vdso_image_x32, arg2); 825 # endif 826 # if defined CONFIG_X86_32 || defined CONFIG_IA32_EMULATION 827 case ARCH_MAP_VDSO_32: 828 return prctl_map_vdso(&vdso_image_32, arg2); 829 # endif 830 case ARCH_MAP_VDSO_64: 831 return prctl_map_vdso(&vdso_image_64, arg2); 832 #endif 833 834 default: 835 ret = -EINVAL; 836 break; 837 } 838 839 return ret; 840 } 841 842 SYSCALL_DEFINE2(arch_prctl, int, option, unsigned long, arg2) 843 { 844 long ret; 845 846 ret = do_arch_prctl_64(current, option, arg2); 847 if (ret == -EINVAL) 848 ret = do_arch_prctl_common(current, option, arg2); 849 850 return ret; 851 } 852 853 #ifdef CONFIG_IA32_EMULATION 854 COMPAT_SYSCALL_DEFINE2(arch_prctl, int, option, unsigned long, arg2) 855 { 856 return do_arch_prctl_common(current, option, arg2); 857 } 858 #endif 859 860 unsigned long KSTK_ESP(struct task_struct *task) 861 { 862 return task_pt_regs(task)->sp; 863 } 864