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 #if __LINUX_ARM_ARCH__ >= 7 347 /* 348 * Clear the If-Then Thumb-2 execution state 349 * ARM spec requires this to be all 000s in ARM mode 350 * Snapdragon S4/Krait misbehaves on a Thumb=>ARM 351 * signal transition without this. 352 */ 353 cpsr &= ~PSR_IT_MASK; 354 #endif 355 356 if (thumb) { 357 cpsr |= PSR_T_BIT; 358 } else 359 cpsr &= ~PSR_T_BIT; 360 } 361 #endif 362 363 if (ksig->ka.sa.sa_flags & SA_RESTORER) { 364 retcode = (unsigned long)ksig->ka.sa.sa_restorer; 365 } else { 366 unsigned int idx = thumb << 1; 367 368 if (ksig->ka.sa.sa_flags & SA_SIGINFO) 369 idx += 3; 370 371 /* 372 * Put the sigreturn code on the stack no matter which return 373 * mechanism we use in order to remain ABI compliant 374 */ 375 if (__put_user(sigreturn_codes[idx], rc) || 376 __put_user(sigreturn_codes[idx+1], rc+1)) 377 return 1; 378 379 #ifdef CONFIG_MMU 380 if (cpsr & MODE32_BIT) { 381 struct mm_struct *mm = current->mm; 382 383 /* 384 * 32-bit code can use the signal return page 385 * except when the MPU has protected the vectors 386 * page from PL0 387 */ 388 retcode = mm->context.sigpage + signal_return_offset + 389 (idx << 2) + thumb; 390 } else 391 #endif 392 { 393 /* 394 * Ensure that the instruction cache sees 395 * the return code written onto the stack. 396 */ 397 flush_icache_range((unsigned long)rc, 398 (unsigned long)(rc + 2)); 399 400 retcode = ((unsigned long)rc) + thumb; 401 } 402 } 403 404 regs->ARM_r0 = ksig->sig; 405 regs->ARM_sp = (unsigned long)frame; 406 regs->ARM_lr = retcode; 407 regs->ARM_pc = handler; 408 regs->ARM_cpsr = cpsr; 409 410 return 0; 411 } 412 413 static int 414 setup_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs) 415 { 416 struct sigframe __user *frame = get_sigframe(ksig, regs, sizeof(*frame)); 417 int err = 0; 418 419 if (!frame) 420 return 1; 421 422 /* 423 * Set uc.uc_flags to a value which sc.trap_no would never have. 424 */ 425 __put_user_error(0x5ac3c35a, &frame->uc.uc_flags, err); 426 427 err |= setup_sigframe(frame, regs, set); 428 if (err == 0) 429 err = setup_return(regs, ksig, frame->retcode, frame); 430 431 return err; 432 } 433 434 static int 435 setup_rt_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs) 436 { 437 struct rt_sigframe __user *frame = get_sigframe(ksig, regs, sizeof(*frame)); 438 int err = 0; 439 440 if (!frame) 441 return 1; 442 443 err |= copy_siginfo_to_user(&frame->info, &ksig->info); 444 445 __put_user_error(0, &frame->sig.uc.uc_flags, err); 446 __put_user_error(NULL, &frame->sig.uc.uc_link, err); 447 448 err |= __save_altstack(&frame->sig.uc.uc_stack, regs->ARM_sp); 449 err |= setup_sigframe(&frame->sig, regs, set); 450 if (err == 0) 451 err = setup_return(regs, ksig, frame->sig.retcode, frame); 452 453 if (err == 0) { 454 /* 455 * For realtime signals we must also set the second and third 456 * arguments for the signal handler. 457 * -- Peter Maydell <pmaydell@chiark.greenend.org.uk> 2000-12-06 458 */ 459 regs->ARM_r1 = (unsigned long)&frame->info; 460 regs->ARM_r2 = (unsigned long)&frame->sig.uc; 461 } 462 463 return err; 464 } 465 466 /* 467 * OK, we're invoking a handler 468 */ 469 static void handle_signal(struct ksignal *ksig, struct pt_regs *regs) 470 { 471 sigset_t *oldset = sigmask_to_save(); 472 int ret; 473 474 /* 475 * Set up the stack frame 476 */ 477 if (ksig->ka.sa.sa_flags & SA_SIGINFO) 478 ret = setup_rt_frame(ksig, oldset, regs); 479 else 480 ret = setup_frame(ksig, oldset, regs); 481 482 /* 483 * Check that the resulting registers are actually sane. 484 */ 485 ret |= !valid_user_regs(regs); 486 487 signal_setup_done(ret, ksig, 0); 488 } 489 490 /* 491 * Note that 'init' is a special process: it doesn't get signals it doesn't 492 * want to handle. Thus you cannot kill init even with a SIGKILL even by 493 * mistake. 494 * 495 * Note that we go through the signals twice: once to check the signals that 496 * the kernel can handle, and then we build all the user-level signal handling 497 * stack-frames in one go after that. 498 */ 499 static int do_signal(struct pt_regs *regs, int syscall) 500 { 501 unsigned int retval = 0, continue_addr = 0, restart_addr = 0; 502 struct ksignal ksig; 503 int restart = 0; 504 505 /* 506 * If we were from a system call, check for system call restarting... 507 */ 508 if (syscall) { 509 continue_addr = regs->ARM_pc; 510 restart_addr = continue_addr - (thumb_mode(regs) ? 2 : 4); 511 retval = regs->ARM_r0; 512 513 /* 514 * Prepare for system call restart. We do this here so that a 515 * debugger will see the already changed PSW. 516 */ 517 switch (retval) { 518 case -ERESTART_RESTARTBLOCK: 519 restart -= 2; 520 case -ERESTARTNOHAND: 521 case -ERESTARTSYS: 522 case -ERESTARTNOINTR: 523 restart++; 524 regs->ARM_r0 = regs->ARM_ORIG_r0; 525 regs->ARM_pc = restart_addr; 526 break; 527 } 528 } 529 530 /* 531 * Get the signal to deliver. When running under ptrace, at this 532 * point the debugger may change all our registers ... 533 */ 534 /* 535 * Depending on the signal settings we may need to revert the 536 * decision to restart the system call. But skip this if a 537 * debugger has chosen to restart at a different PC. 538 */ 539 if (get_signal(&ksig)) { 540 /* handler */ 541 if (unlikely(restart) && regs->ARM_pc == restart_addr) { 542 if (retval == -ERESTARTNOHAND || 543 retval == -ERESTART_RESTARTBLOCK 544 || (retval == -ERESTARTSYS 545 && !(ksig.ka.sa.sa_flags & SA_RESTART))) { 546 regs->ARM_r0 = -EINTR; 547 regs->ARM_pc = continue_addr; 548 } 549 } 550 handle_signal(&ksig, regs); 551 } else { 552 /* no handler */ 553 restore_saved_sigmask(); 554 if (unlikely(restart) && regs->ARM_pc == restart_addr) { 555 regs->ARM_pc = continue_addr; 556 return restart; 557 } 558 } 559 return 0; 560 } 561 562 asmlinkage int 563 do_work_pending(struct pt_regs *regs, unsigned int thread_flags, int syscall) 564 { 565 do { 566 if (likely(thread_flags & _TIF_NEED_RESCHED)) { 567 schedule(); 568 } else { 569 if (unlikely(!user_mode(regs))) 570 return 0; 571 local_irq_enable(); 572 if (thread_flags & _TIF_SIGPENDING) { 573 int restart = do_signal(regs, syscall); 574 if (unlikely(restart)) { 575 /* 576 * Restart without handlers. 577 * Deal with it without leaving 578 * the kernel space. 579 */ 580 return restart; 581 } 582 syscall = 0; 583 } else if (thread_flags & _TIF_UPROBE) { 584 uprobe_notify_resume(regs); 585 } else { 586 clear_thread_flag(TIF_NOTIFY_RESUME); 587 tracehook_notify_resume(regs); 588 } 589 } 590 local_irq_disable(); 591 thread_flags = current_thread_info()->flags; 592 } while (thread_flags & _TIF_WORK_MASK); 593 return 0; 594 } 595 596 struct page *get_signal_page(void) 597 { 598 unsigned long ptr; 599 unsigned offset; 600 struct page *page; 601 void *addr; 602 603 page = alloc_pages(GFP_KERNEL, 0); 604 605 if (!page) 606 return NULL; 607 608 addr = page_address(page); 609 610 /* Give the signal return code some randomness */ 611 offset = 0x200 + (get_random_int() & 0x7fc); 612 signal_return_offset = offset; 613 614 /* 615 * Copy signal return handlers into the vector page, and 616 * set sigreturn to be a pointer to these. 617 */ 618 memcpy(addr + offset, sigreturn_codes, sizeof(sigreturn_codes)); 619 620 ptr = (unsigned long)addr + offset; 621 flush_icache_range(ptr, ptr + sizeof(sigreturn_codes)); 622 623 return page; 624 } 625