1 /* 2 * linux/arch/arm/kernel/signal.c 3 * 4 * Copyright (C) 1995-2009 Russell King 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License version 2 as 8 * published by the Free Software Foundation. 9 */ 10 #include <linux/errno.h> 11 #include <linux/random.h> 12 #include <linux/signal.h> 13 #include <linux/personality.h> 14 #include <linux/uaccess.h> 15 #include <linux/tracehook.h> 16 #include <linux/uprobes.h> 17 18 #include <asm/elf.h> 19 #include <asm/cacheflush.h> 20 #include <asm/traps.h> 21 #include <asm/ucontext.h> 22 #include <asm/unistd.h> 23 #include <asm/vfp.h> 24 25 extern const unsigned long sigreturn_codes[7]; 26 27 static unsigned long signal_return_offset; 28 29 #ifdef CONFIG_CRUNCH 30 static int preserve_crunch_context(struct crunch_sigframe __user *frame) 31 { 32 char kbuf[sizeof(*frame) + 8]; 33 struct crunch_sigframe *kframe; 34 35 /* the crunch context must be 64 bit aligned */ 36 kframe = (struct crunch_sigframe *)((unsigned long)(kbuf + 8) & ~7); 37 kframe->magic = CRUNCH_MAGIC; 38 kframe->size = CRUNCH_STORAGE_SIZE; 39 crunch_task_copy(current_thread_info(), &kframe->storage); 40 return __copy_to_user(frame, kframe, sizeof(*frame)); 41 } 42 43 static int restore_crunch_context(struct crunch_sigframe __user *frame) 44 { 45 char kbuf[sizeof(*frame) + 8]; 46 struct crunch_sigframe *kframe; 47 48 /* the crunch context must be 64 bit aligned */ 49 kframe = (struct crunch_sigframe *)((unsigned long)(kbuf + 8) & ~7); 50 if (__copy_from_user(kframe, frame, sizeof(*frame))) 51 return -1; 52 if (kframe->magic != CRUNCH_MAGIC || 53 kframe->size != CRUNCH_STORAGE_SIZE) 54 return -1; 55 crunch_task_restore(current_thread_info(), &kframe->storage); 56 return 0; 57 } 58 #endif 59 60 #ifdef CONFIG_IWMMXT 61 62 static int preserve_iwmmxt_context(struct iwmmxt_sigframe *frame) 63 { 64 char kbuf[sizeof(*frame) + 8]; 65 struct iwmmxt_sigframe *kframe; 66 67 /* the iWMMXt context must be 64 bit aligned */ 68 kframe = (struct iwmmxt_sigframe *)((unsigned long)(kbuf + 8) & ~7); 69 kframe->magic = IWMMXT_MAGIC; 70 kframe->size = IWMMXT_STORAGE_SIZE; 71 iwmmxt_task_copy(current_thread_info(), &kframe->storage); 72 return __copy_to_user(frame, kframe, sizeof(*frame)); 73 } 74 75 static int restore_iwmmxt_context(struct iwmmxt_sigframe *frame) 76 { 77 char kbuf[sizeof(*frame) + 8]; 78 struct iwmmxt_sigframe *kframe; 79 80 /* the iWMMXt context must be 64 bit aligned */ 81 kframe = (struct iwmmxt_sigframe *)((unsigned long)(kbuf + 8) & ~7); 82 if (__copy_from_user(kframe, frame, sizeof(*frame))) 83 return -1; 84 if (kframe->magic != IWMMXT_MAGIC || 85 kframe->size != IWMMXT_STORAGE_SIZE) 86 return -1; 87 iwmmxt_task_restore(current_thread_info(), &kframe->storage); 88 return 0; 89 } 90 91 #endif 92 93 #ifdef CONFIG_VFP 94 95 static int preserve_vfp_context(struct vfp_sigframe __user *frame) 96 { 97 const unsigned long magic = VFP_MAGIC; 98 const unsigned long size = VFP_STORAGE_SIZE; 99 int err = 0; 100 101 __put_user_error(magic, &frame->magic, err); 102 __put_user_error(size, &frame->size, err); 103 104 if (err) 105 return -EFAULT; 106 107 return vfp_preserve_user_clear_hwstate(&frame->ufp, &frame->ufp_exc); 108 } 109 110 static int restore_vfp_context(struct vfp_sigframe __user *frame) 111 { 112 unsigned long magic; 113 unsigned long size; 114 int err = 0; 115 116 __get_user_error(magic, &frame->magic, err); 117 __get_user_error(size, &frame->size, err); 118 119 if (err) 120 return -EFAULT; 121 if (magic != VFP_MAGIC || size != VFP_STORAGE_SIZE) 122 return -EINVAL; 123 124 return vfp_restore_user_hwstate(&frame->ufp, &frame->ufp_exc); 125 } 126 127 #endif 128 129 /* 130 * Do a signal return; undo the signal stack. These are aligned to 64-bit. 131 */ 132 struct sigframe { 133 struct ucontext uc; 134 unsigned long retcode[2]; 135 }; 136 137 struct rt_sigframe { 138 struct siginfo info; 139 struct sigframe sig; 140 }; 141 142 static int restore_sigframe(struct pt_regs *regs, struct sigframe __user *sf) 143 { 144 struct aux_sigframe __user *aux; 145 sigset_t set; 146 int err; 147 148 err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set)); 149 if (err == 0) 150 set_current_blocked(&set); 151 152 __get_user_error(regs->ARM_r0, &sf->uc.uc_mcontext.arm_r0, err); 153 __get_user_error(regs->ARM_r1, &sf->uc.uc_mcontext.arm_r1, err); 154 __get_user_error(regs->ARM_r2, &sf->uc.uc_mcontext.arm_r2, err); 155 __get_user_error(regs->ARM_r3, &sf->uc.uc_mcontext.arm_r3, err); 156 __get_user_error(regs->ARM_r4, &sf->uc.uc_mcontext.arm_r4, err); 157 __get_user_error(regs->ARM_r5, &sf->uc.uc_mcontext.arm_r5, err); 158 __get_user_error(regs->ARM_r6, &sf->uc.uc_mcontext.arm_r6, err); 159 __get_user_error(regs->ARM_r7, &sf->uc.uc_mcontext.arm_r7, err); 160 __get_user_error(regs->ARM_r8, &sf->uc.uc_mcontext.arm_r8, err); 161 __get_user_error(regs->ARM_r9, &sf->uc.uc_mcontext.arm_r9, err); 162 __get_user_error(regs->ARM_r10, &sf->uc.uc_mcontext.arm_r10, err); 163 __get_user_error(regs->ARM_fp, &sf->uc.uc_mcontext.arm_fp, err); 164 __get_user_error(regs->ARM_ip, &sf->uc.uc_mcontext.arm_ip, err); 165 __get_user_error(regs->ARM_sp, &sf->uc.uc_mcontext.arm_sp, err); 166 __get_user_error(regs->ARM_lr, &sf->uc.uc_mcontext.arm_lr, err); 167 __get_user_error(regs->ARM_pc, &sf->uc.uc_mcontext.arm_pc, err); 168 __get_user_error(regs->ARM_cpsr, &sf->uc.uc_mcontext.arm_cpsr, err); 169 170 err |= !valid_user_regs(regs); 171 172 aux = (struct aux_sigframe __user *) sf->uc.uc_regspace; 173 #ifdef CONFIG_CRUNCH 174 if (err == 0) 175 err |= restore_crunch_context(&aux->crunch); 176 #endif 177 #ifdef CONFIG_IWMMXT 178 if (err == 0 && test_thread_flag(TIF_USING_IWMMXT)) 179 err |= restore_iwmmxt_context(&aux->iwmmxt); 180 #endif 181 #ifdef CONFIG_VFP 182 if (err == 0) 183 err |= restore_vfp_context(&aux->vfp); 184 #endif 185 186 return err; 187 } 188 189 asmlinkage int sys_sigreturn(struct pt_regs *regs) 190 { 191 struct sigframe __user *frame; 192 193 /* Always make any pending restarted system calls return -EINTR */ 194 current->restart_block.fn = do_no_restart_syscall; 195 196 /* 197 * Since we stacked the signal on a 64-bit boundary, 198 * then 'sp' should be word aligned here. If it's 199 * not, then the user is trying to mess with us. 200 */ 201 if (regs->ARM_sp & 7) 202 goto badframe; 203 204 frame = (struct sigframe __user *)regs->ARM_sp; 205 206 if (!access_ok(VERIFY_READ, frame, sizeof (*frame))) 207 goto badframe; 208 209 if (restore_sigframe(regs, frame)) 210 goto badframe; 211 212 return regs->ARM_r0; 213 214 badframe: 215 force_sig(SIGSEGV, current); 216 return 0; 217 } 218 219 asmlinkage int sys_rt_sigreturn(struct pt_regs *regs) 220 { 221 struct rt_sigframe __user *frame; 222 223 /* Always make any pending restarted system calls return -EINTR */ 224 current->restart_block.fn = do_no_restart_syscall; 225 226 /* 227 * Since we stacked the signal on a 64-bit boundary, 228 * then 'sp' should be word aligned here. If it's 229 * not, then the user is trying to mess with us. 230 */ 231 if (regs->ARM_sp & 7) 232 goto badframe; 233 234 frame = (struct rt_sigframe __user *)regs->ARM_sp; 235 236 if (!access_ok(VERIFY_READ, frame, sizeof (*frame))) 237 goto badframe; 238 239 if (restore_sigframe(regs, &frame->sig)) 240 goto badframe; 241 242 if (restore_altstack(&frame->sig.uc.uc_stack)) 243 goto badframe; 244 245 return regs->ARM_r0; 246 247 badframe: 248 force_sig(SIGSEGV, current); 249 return 0; 250 } 251 252 static int 253 setup_sigframe(struct sigframe __user *sf, struct pt_regs *regs, sigset_t *set) 254 { 255 struct aux_sigframe __user *aux; 256 int err = 0; 257 258 __put_user_error(regs->ARM_r0, &sf->uc.uc_mcontext.arm_r0, err); 259 __put_user_error(regs->ARM_r1, &sf->uc.uc_mcontext.arm_r1, err); 260 __put_user_error(regs->ARM_r2, &sf->uc.uc_mcontext.arm_r2, err); 261 __put_user_error(regs->ARM_r3, &sf->uc.uc_mcontext.arm_r3, err); 262 __put_user_error(regs->ARM_r4, &sf->uc.uc_mcontext.arm_r4, err); 263 __put_user_error(regs->ARM_r5, &sf->uc.uc_mcontext.arm_r5, err); 264 __put_user_error(regs->ARM_r6, &sf->uc.uc_mcontext.arm_r6, err); 265 __put_user_error(regs->ARM_r7, &sf->uc.uc_mcontext.arm_r7, err); 266 __put_user_error(regs->ARM_r8, &sf->uc.uc_mcontext.arm_r8, err); 267 __put_user_error(regs->ARM_r9, &sf->uc.uc_mcontext.arm_r9, err); 268 __put_user_error(regs->ARM_r10, &sf->uc.uc_mcontext.arm_r10, err); 269 __put_user_error(regs->ARM_fp, &sf->uc.uc_mcontext.arm_fp, err); 270 __put_user_error(regs->ARM_ip, &sf->uc.uc_mcontext.arm_ip, err); 271 __put_user_error(regs->ARM_sp, &sf->uc.uc_mcontext.arm_sp, err); 272 __put_user_error(regs->ARM_lr, &sf->uc.uc_mcontext.arm_lr, err); 273 __put_user_error(regs->ARM_pc, &sf->uc.uc_mcontext.arm_pc, err); 274 __put_user_error(regs->ARM_cpsr, &sf->uc.uc_mcontext.arm_cpsr, err); 275 276 __put_user_error(current->thread.trap_no, &sf->uc.uc_mcontext.trap_no, err); 277 __put_user_error(current->thread.error_code, &sf->uc.uc_mcontext.error_code, err); 278 __put_user_error(current->thread.address, &sf->uc.uc_mcontext.fault_address, err); 279 __put_user_error(set->sig[0], &sf->uc.uc_mcontext.oldmask, err); 280 281 err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(*set)); 282 283 aux = (struct aux_sigframe __user *) sf->uc.uc_regspace; 284 #ifdef CONFIG_CRUNCH 285 if (err == 0) 286 err |= preserve_crunch_context(&aux->crunch); 287 #endif 288 #ifdef CONFIG_IWMMXT 289 if (err == 0 && test_thread_flag(TIF_USING_IWMMXT)) 290 err |= preserve_iwmmxt_context(&aux->iwmmxt); 291 #endif 292 #ifdef CONFIG_VFP 293 if (err == 0) 294 err |= preserve_vfp_context(&aux->vfp); 295 #endif 296 __put_user_error(0, &aux->end_magic, err); 297 298 return err; 299 } 300 301 static inline void __user * 302 get_sigframe(struct ksignal *ksig, struct pt_regs *regs, int framesize) 303 { 304 unsigned long sp = sigsp(regs->ARM_sp, ksig); 305 void __user *frame; 306 307 /* 308 * ATPCS B01 mandates 8-byte alignment 309 */ 310 frame = (void __user *)((sp - framesize) & ~7); 311 312 /* 313 * Check that we can actually write to the signal frame. 314 */ 315 if (!access_ok(VERIFY_WRITE, frame, framesize)) 316 frame = NULL; 317 318 return frame; 319 } 320 321 static int 322 setup_return(struct pt_regs *regs, struct ksignal *ksig, 323 unsigned long __user *rc, void __user *frame) 324 { 325 unsigned long handler = (unsigned long)ksig->ka.sa.sa_handler; 326 unsigned long retcode; 327 int thumb = 0; 328 unsigned long cpsr = regs->ARM_cpsr & ~(PSR_f | PSR_E_BIT); 329 330 cpsr |= PSR_ENDSTATE; 331 332 /* 333 * Maybe we need to deliver a 32-bit signal to a 26-bit task. 334 */ 335 if (ksig->ka.sa.sa_flags & SA_THIRTYTWO) 336 cpsr = (cpsr & ~MODE_MASK) | USR_MODE; 337 338 #ifdef CONFIG_ARM_THUMB 339 if (elf_hwcap & HWCAP_THUMB) { 340 /* 341 * The LSB of the handler determines if we're going to 342 * be using THUMB or ARM mode for this signal handler. 343 */ 344 thumb = handler & 1; 345 346 /* 347 * Clear the If-Then Thumb-2 execution state. ARM spec 348 * requires this to be all 000s in ARM mode. Snapdragon 349 * S4/Krait misbehaves on a Thumb=>ARM signal transition 350 * without this. 351 * 352 * We must do this whenever we are running on a Thumb-2 353 * capable CPU, which includes ARMv6T2. However, we elect 354 * to always do this to simplify the code; this field is 355 * marked UNK/SBZP for older architectures. 356 */ 357 cpsr &= ~PSR_IT_MASK; 358 359 if (thumb) { 360 cpsr |= PSR_T_BIT; 361 } else 362 cpsr &= ~PSR_T_BIT; 363 } 364 #endif 365 366 if (ksig->ka.sa.sa_flags & SA_RESTORER) { 367 retcode = (unsigned long)ksig->ka.sa.sa_restorer; 368 } else { 369 unsigned int idx = thumb << 1; 370 371 if (ksig->ka.sa.sa_flags & SA_SIGINFO) 372 idx += 3; 373 374 /* 375 * Put the sigreturn code on the stack no matter which return 376 * mechanism we use in order to remain ABI compliant 377 */ 378 if (__put_user(sigreturn_codes[idx], rc) || 379 __put_user(sigreturn_codes[idx+1], rc+1)) 380 return 1; 381 382 #ifdef CONFIG_MMU 383 if (cpsr & MODE32_BIT) { 384 struct mm_struct *mm = current->mm; 385 386 /* 387 * 32-bit code can use the signal return page 388 * except when the MPU has protected the vectors 389 * page from PL0 390 */ 391 retcode = mm->context.sigpage + signal_return_offset + 392 (idx << 2) + thumb; 393 } else 394 #endif 395 { 396 /* 397 * Ensure that the instruction cache sees 398 * the return code written onto the stack. 399 */ 400 flush_icache_range((unsigned long)rc, 401 (unsigned long)(rc + 2)); 402 403 retcode = ((unsigned long)rc) + thumb; 404 } 405 } 406 407 regs->ARM_r0 = ksig->sig; 408 regs->ARM_sp = (unsigned long)frame; 409 regs->ARM_lr = retcode; 410 regs->ARM_pc = handler; 411 regs->ARM_cpsr = cpsr; 412 413 return 0; 414 } 415 416 static int 417 setup_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs) 418 { 419 struct sigframe __user *frame = get_sigframe(ksig, regs, sizeof(*frame)); 420 int err = 0; 421 422 if (!frame) 423 return 1; 424 425 /* 426 * Set uc.uc_flags to a value which sc.trap_no would never have. 427 */ 428 __put_user_error(0x5ac3c35a, &frame->uc.uc_flags, err); 429 430 err |= setup_sigframe(frame, regs, set); 431 if (err == 0) 432 err = setup_return(regs, ksig, frame->retcode, frame); 433 434 return err; 435 } 436 437 static int 438 setup_rt_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs) 439 { 440 struct rt_sigframe __user *frame = get_sigframe(ksig, regs, sizeof(*frame)); 441 int err = 0; 442 443 if (!frame) 444 return 1; 445 446 err |= copy_siginfo_to_user(&frame->info, &ksig->info); 447 448 __put_user_error(0, &frame->sig.uc.uc_flags, err); 449 __put_user_error(NULL, &frame->sig.uc.uc_link, err); 450 451 err |= __save_altstack(&frame->sig.uc.uc_stack, regs->ARM_sp); 452 err |= setup_sigframe(&frame->sig, regs, set); 453 if (err == 0) 454 err = setup_return(regs, ksig, frame->sig.retcode, frame); 455 456 if (err == 0) { 457 /* 458 * For realtime signals we must also set the second and third 459 * arguments for the signal handler. 460 * -- Peter Maydell <pmaydell@chiark.greenend.org.uk> 2000-12-06 461 */ 462 regs->ARM_r1 = (unsigned long)&frame->info; 463 regs->ARM_r2 = (unsigned long)&frame->sig.uc; 464 } 465 466 return err; 467 } 468 469 /* 470 * OK, we're invoking a handler 471 */ 472 static void handle_signal(struct ksignal *ksig, struct pt_regs *regs) 473 { 474 sigset_t *oldset = sigmask_to_save(); 475 int ret; 476 477 /* 478 * Set up the stack frame 479 */ 480 if (ksig->ka.sa.sa_flags & SA_SIGINFO) 481 ret = setup_rt_frame(ksig, oldset, regs); 482 else 483 ret = setup_frame(ksig, oldset, regs); 484 485 /* 486 * Check that the resulting registers are actually sane. 487 */ 488 ret |= !valid_user_regs(regs); 489 490 signal_setup_done(ret, ksig, 0); 491 } 492 493 /* 494 * Note that 'init' is a special process: it doesn't get signals it doesn't 495 * want to handle. Thus you cannot kill init even with a SIGKILL even by 496 * mistake. 497 * 498 * Note that we go through the signals twice: once to check the signals that 499 * the kernel can handle, and then we build all the user-level signal handling 500 * stack-frames in one go after that. 501 */ 502 static int do_signal(struct pt_regs *regs, int syscall) 503 { 504 unsigned int retval = 0, continue_addr = 0, restart_addr = 0; 505 struct ksignal ksig; 506 int restart = 0; 507 508 /* 509 * If we were from a system call, check for system call restarting... 510 */ 511 if (syscall) { 512 continue_addr = regs->ARM_pc; 513 restart_addr = continue_addr - (thumb_mode(regs) ? 2 : 4); 514 retval = regs->ARM_r0; 515 516 /* 517 * Prepare for system call restart. We do this here so that a 518 * debugger will see the already changed PSW. 519 */ 520 switch (retval) { 521 case -ERESTART_RESTARTBLOCK: 522 restart -= 2; 523 case -ERESTARTNOHAND: 524 case -ERESTARTSYS: 525 case -ERESTARTNOINTR: 526 restart++; 527 regs->ARM_r0 = regs->ARM_ORIG_r0; 528 regs->ARM_pc = restart_addr; 529 break; 530 } 531 } 532 533 /* 534 * Get the signal to deliver. When running under ptrace, at this 535 * point the debugger may change all our registers ... 536 */ 537 /* 538 * Depending on the signal settings we may need to revert the 539 * decision to restart the system call. But skip this if a 540 * debugger has chosen to restart at a different PC. 541 */ 542 if (get_signal(&ksig)) { 543 /* handler */ 544 if (unlikely(restart) && regs->ARM_pc == restart_addr) { 545 if (retval == -ERESTARTNOHAND || 546 retval == -ERESTART_RESTARTBLOCK 547 || (retval == -ERESTARTSYS 548 && !(ksig.ka.sa.sa_flags & SA_RESTART))) { 549 regs->ARM_r0 = -EINTR; 550 regs->ARM_pc = continue_addr; 551 } 552 } 553 handle_signal(&ksig, regs); 554 } else { 555 /* no handler */ 556 restore_saved_sigmask(); 557 if (unlikely(restart) && regs->ARM_pc == restart_addr) { 558 regs->ARM_pc = continue_addr; 559 return restart; 560 } 561 } 562 return 0; 563 } 564 565 asmlinkage int 566 do_work_pending(struct pt_regs *regs, unsigned int thread_flags, int syscall) 567 { 568 /* 569 * The assembly code enters us with IRQs off, but it hasn't 570 * informed the tracing code of that for efficiency reasons. 571 * Update the trace code with the current status. 572 */ 573 trace_hardirqs_off(); 574 do { 575 if (likely(thread_flags & _TIF_NEED_RESCHED)) { 576 schedule(); 577 } else { 578 if (unlikely(!user_mode(regs))) 579 return 0; 580 local_irq_enable(); 581 if (thread_flags & _TIF_SIGPENDING) { 582 int restart = do_signal(regs, syscall); 583 if (unlikely(restart)) { 584 /* 585 * Restart without handlers. 586 * Deal with it without leaving 587 * the kernel space. 588 */ 589 return restart; 590 } 591 syscall = 0; 592 } else if (thread_flags & _TIF_UPROBE) { 593 uprobe_notify_resume(regs); 594 } else { 595 clear_thread_flag(TIF_NOTIFY_RESUME); 596 tracehook_notify_resume(regs); 597 } 598 } 599 local_irq_disable(); 600 thread_flags = current_thread_info()->flags; 601 } while (thread_flags & _TIF_WORK_MASK); 602 return 0; 603 } 604 605 struct page *get_signal_page(void) 606 { 607 unsigned long ptr; 608 unsigned offset; 609 struct page *page; 610 void *addr; 611 612 page = alloc_pages(GFP_KERNEL, 0); 613 614 if (!page) 615 return NULL; 616 617 addr = page_address(page); 618 619 /* Give the signal return code some randomness */ 620 offset = 0x200 + (get_random_int() & 0x7fc); 621 signal_return_offset = offset; 622 623 /* 624 * Copy signal return handlers into the vector page, and 625 * set sigreturn to be a pointer to these. 626 */ 627 memcpy(addr + offset, sigreturn_codes, sizeof(sigreturn_codes)); 628 629 ptr = (unsigned long)addr + offset; 630 flush_icache_range(ptr, ptr + sizeof(sigreturn_codes)); 631 632 return page; 633 } 634