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