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/signal.h> 12 #include <linux/personality.h> 13 #include <linux/uaccess.h> 14 #include <linux/tracehook.h> 15 16 #include <asm/elf.h> 17 #include <asm/cacheflush.h> 18 #include <asm/ucontext.h> 19 #include <asm/unistd.h> 20 #include <asm/vfp.h> 21 22 #include "signal.h" 23 24 /* 25 * For ARM syscalls, we encode the syscall number into the instruction. 26 */ 27 #define SWI_SYS_SIGRETURN (0xef000000|(__NR_sigreturn)|(__NR_OABI_SYSCALL_BASE)) 28 #define SWI_SYS_RT_SIGRETURN (0xef000000|(__NR_rt_sigreturn)|(__NR_OABI_SYSCALL_BASE)) 29 30 /* 31 * With EABI, the syscall number has to be loaded into r7. 32 */ 33 #define MOV_R7_NR_SIGRETURN (0xe3a07000 | (__NR_sigreturn - __NR_SYSCALL_BASE)) 34 #define MOV_R7_NR_RT_SIGRETURN (0xe3a07000 | (__NR_rt_sigreturn - __NR_SYSCALL_BASE)) 35 36 /* 37 * For Thumb syscalls, we pass the syscall number via r7. We therefore 38 * need two 16-bit instructions. 39 */ 40 #define SWI_THUMB_SIGRETURN (0xdf00 << 16 | 0x2700 | (__NR_sigreturn - __NR_SYSCALL_BASE)) 41 #define SWI_THUMB_RT_SIGRETURN (0xdf00 << 16 | 0x2700 | (__NR_rt_sigreturn - __NR_SYSCALL_BASE)) 42 43 const unsigned long sigreturn_codes[7] = { 44 MOV_R7_NR_SIGRETURN, SWI_SYS_SIGRETURN, SWI_THUMB_SIGRETURN, 45 MOV_R7_NR_RT_SIGRETURN, SWI_SYS_RT_SIGRETURN, SWI_THUMB_RT_SIGRETURN, 46 }; 47 48 #ifdef CONFIG_CRUNCH 49 static int preserve_crunch_context(struct crunch_sigframe __user *frame) 50 { 51 char kbuf[sizeof(*frame) + 8]; 52 struct crunch_sigframe *kframe; 53 54 /* the crunch context must be 64 bit aligned */ 55 kframe = (struct crunch_sigframe *)((unsigned long)(kbuf + 8) & ~7); 56 kframe->magic = CRUNCH_MAGIC; 57 kframe->size = CRUNCH_STORAGE_SIZE; 58 crunch_task_copy(current_thread_info(), &kframe->storage); 59 return __copy_to_user(frame, kframe, sizeof(*frame)); 60 } 61 62 static int restore_crunch_context(struct crunch_sigframe __user *frame) 63 { 64 char kbuf[sizeof(*frame) + 8]; 65 struct crunch_sigframe *kframe; 66 67 /* the crunch context must be 64 bit aligned */ 68 kframe = (struct crunch_sigframe *)((unsigned long)(kbuf + 8) & ~7); 69 if (__copy_from_user(kframe, frame, sizeof(*frame))) 70 return -1; 71 if (kframe->magic != CRUNCH_MAGIC || 72 kframe->size != CRUNCH_STORAGE_SIZE) 73 return -1; 74 crunch_task_restore(current_thread_info(), &kframe->storage); 75 return 0; 76 } 77 #endif 78 79 #ifdef CONFIG_IWMMXT 80 81 static int preserve_iwmmxt_context(struct iwmmxt_sigframe *frame) 82 { 83 char kbuf[sizeof(*frame) + 8]; 84 struct iwmmxt_sigframe *kframe; 85 86 /* the iWMMXt context must be 64 bit aligned */ 87 kframe = (struct iwmmxt_sigframe *)((unsigned long)(kbuf + 8) & ~7); 88 kframe->magic = IWMMXT_MAGIC; 89 kframe->size = IWMMXT_STORAGE_SIZE; 90 iwmmxt_task_copy(current_thread_info(), &kframe->storage); 91 return __copy_to_user(frame, kframe, sizeof(*frame)); 92 } 93 94 static int restore_iwmmxt_context(struct iwmmxt_sigframe *frame) 95 { 96 char kbuf[sizeof(*frame) + 8]; 97 struct iwmmxt_sigframe *kframe; 98 99 /* the iWMMXt context must be 64 bit aligned */ 100 kframe = (struct iwmmxt_sigframe *)((unsigned long)(kbuf + 8) & ~7); 101 if (__copy_from_user(kframe, frame, sizeof(*frame))) 102 return -1; 103 if (kframe->magic != IWMMXT_MAGIC || 104 kframe->size != IWMMXT_STORAGE_SIZE) 105 return -1; 106 iwmmxt_task_restore(current_thread_info(), &kframe->storage); 107 return 0; 108 } 109 110 #endif 111 112 #ifdef CONFIG_VFP 113 114 static int preserve_vfp_context(struct vfp_sigframe __user *frame) 115 { 116 const unsigned long magic = VFP_MAGIC; 117 const unsigned long size = VFP_STORAGE_SIZE; 118 int err = 0; 119 120 __put_user_error(magic, &frame->magic, err); 121 __put_user_error(size, &frame->size, err); 122 123 if (err) 124 return -EFAULT; 125 126 return vfp_preserve_user_clear_hwstate(&frame->ufp, &frame->ufp_exc); 127 } 128 129 static int restore_vfp_context(struct vfp_sigframe __user *frame) 130 { 131 unsigned long magic; 132 unsigned long size; 133 int err = 0; 134 135 __get_user_error(magic, &frame->magic, err); 136 __get_user_error(size, &frame->size, err); 137 138 if (err) 139 return -EFAULT; 140 if (magic != VFP_MAGIC || size != VFP_STORAGE_SIZE) 141 return -EINVAL; 142 143 return vfp_restore_user_hwstate(&frame->ufp, &frame->ufp_exc); 144 } 145 146 #endif 147 148 /* 149 * Do a signal return; undo the signal stack. These are aligned to 64-bit. 150 */ 151 struct sigframe { 152 struct ucontext uc; 153 unsigned long retcode[2]; 154 }; 155 156 struct rt_sigframe { 157 struct siginfo info; 158 struct sigframe sig; 159 }; 160 161 static int restore_sigframe(struct pt_regs *regs, struct sigframe __user *sf) 162 { 163 struct aux_sigframe __user *aux; 164 sigset_t set; 165 int err; 166 167 err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set)); 168 if (err == 0) 169 set_current_blocked(&set); 170 171 __get_user_error(regs->ARM_r0, &sf->uc.uc_mcontext.arm_r0, err); 172 __get_user_error(regs->ARM_r1, &sf->uc.uc_mcontext.arm_r1, err); 173 __get_user_error(regs->ARM_r2, &sf->uc.uc_mcontext.arm_r2, err); 174 __get_user_error(regs->ARM_r3, &sf->uc.uc_mcontext.arm_r3, err); 175 __get_user_error(regs->ARM_r4, &sf->uc.uc_mcontext.arm_r4, err); 176 __get_user_error(regs->ARM_r5, &sf->uc.uc_mcontext.arm_r5, err); 177 __get_user_error(regs->ARM_r6, &sf->uc.uc_mcontext.arm_r6, err); 178 __get_user_error(regs->ARM_r7, &sf->uc.uc_mcontext.arm_r7, err); 179 __get_user_error(regs->ARM_r8, &sf->uc.uc_mcontext.arm_r8, err); 180 __get_user_error(regs->ARM_r9, &sf->uc.uc_mcontext.arm_r9, err); 181 __get_user_error(regs->ARM_r10, &sf->uc.uc_mcontext.arm_r10, err); 182 __get_user_error(regs->ARM_fp, &sf->uc.uc_mcontext.arm_fp, err); 183 __get_user_error(regs->ARM_ip, &sf->uc.uc_mcontext.arm_ip, err); 184 __get_user_error(regs->ARM_sp, &sf->uc.uc_mcontext.arm_sp, err); 185 __get_user_error(regs->ARM_lr, &sf->uc.uc_mcontext.arm_lr, err); 186 __get_user_error(regs->ARM_pc, &sf->uc.uc_mcontext.arm_pc, err); 187 __get_user_error(regs->ARM_cpsr, &sf->uc.uc_mcontext.arm_cpsr, err); 188 189 err |= !valid_user_regs(regs); 190 191 aux = (struct aux_sigframe __user *) sf->uc.uc_regspace; 192 #ifdef CONFIG_CRUNCH 193 if (err == 0) 194 err |= restore_crunch_context(&aux->crunch); 195 #endif 196 #ifdef CONFIG_IWMMXT 197 if (err == 0 && test_thread_flag(TIF_USING_IWMMXT)) 198 err |= restore_iwmmxt_context(&aux->iwmmxt); 199 #endif 200 #ifdef CONFIG_VFP 201 if (err == 0) 202 err |= restore_vfp_context(&aux->vfp); 203 #endif 204 205 return err; 206 } 207 208 asmlinkage int sys_sigreturn(struct pt_regs *regs) 209 { 210 struct sigframe __user *frame; 211 212 /* Always make any pending restarted system calls return -EINTR */ 213 current_thread_info()->restart_block.fn = do_no_restart_syscall; 214 215 /* 216 * Since we stacked the signal on a 64-bit boundary, 217 * then 'sp' should be word aligned here. If it's 218 * not, then the user is trying to mess with us. 219 */ 220 if (regs->ARM_sp & 7) 221 goto badframe; 222 223 frame = (struct sigframe __user *)regs->ARM_sp; 224 225 if (!access_ok(VERIFY_READ, frame, sizeof (*frame))) 226 goto badframe; 227 228 if (restore_sigframe(regs, frame)) 229 goto badframe; 230 231 return regs->ARM_r0; 232 233 badframe: 234 force_sig(SIGSEGV, current); 235 return 0; 236 } 237 238 asmlinkage int sys_rt_sigreturn(struct pt_regs *regs) 239 { 240 struct rt_sigframe __user *frame; 241 242 /* Always make any pending restarted system calls return -EINTR */ 243 current_thread_info()->restart_block.fn = do_no_restart_syscall; 244 245 /* 246 * Since we stacked the signal on a 64-bit boundary, 247 * then 'sp' should be word aligned here. If it's 248 * not, then the user is trying to mess with us. 249 */ 250 if (regs->ARM_sp & 7) 251 goto badframe; 252 253 frame = (struct rt_sigframe __user *)regs->ARM_sp; 254 255 if (!access_ok(VERIFY_READ, frame, sizeof (*frame))) 256 goto badframe; 257 258 if (restore_sigframe(regs, &frame->sig)) 259 goto badframe; 260 261 if (restore_altstack(&frame->sig.uc.uc_stack)) 262 goto badframe; 263 264 return regs->ARM_r0; 265 266 badframe: 267 force_sig(SIGSEGV, current); 268 return 0; 269 } 270 271 static int 272 setup_sigframe(struct sigframe __user *sf, struct pt_regs *regs, sigset_t *set) 273 { 274 struct aux_sigframe __user *aux; 275 int err = 0; 276 277 __put_user_error(regs->ARM_r0, &sf->uc.uc_mcontext.arm_r0, err); 278 __put_user_error(regs->ARM_r1, &sf->uc.uc_mcontext.arm_r1, err); 279 __put_user_error(regs->ARM_r2, &sf->uc.uc_mcontext.arm_r2, err); 280 __put_user_error(regs->ARM_r3, &sf->uc.uc_mcontext.arm_r3, err); 281 __put_user_error(regs->ARM_r4, &sf->uc.uc_mcontext.arm_r4, err); 282 __put_user_error(regs->ARM_r5, &sf->uc.uc_mcontext.arm_r5, err); 283 __put_user_error(regs->ARM_r6, &sf->uc.uc_mcontext.arm_r6, err); 284 __put_user_error(regs->ARM_r7, &sf->uc.uc_mcontext.arm_r7, err); 285 __put_user_error(regs->ARM_r8, &sf->uc.uc_mcontext.arm_r8, err); 286 __put_user_error(regs->ARM_r9, &sf->uc.uc_mcontext.arm_r9, err); 287 __put_user_error(regs->ARM_r10, &sf->uc.uc_mcontext.arm_r10, err); 288 __put_user_error(regs->ARM_fp, &sf->uc.uc_mcontext.arm_fp, err); 289 __put_user_error(regs->ARM_ip, &sf->uc.uc_mcontext.arm_ip, err); 290 __put_user_error(regs->ARM_sp, &sf->uc.uc_mcontext.arm_sp, err); 291 __put_user_error(regs->ARM_lr, &sf->uc.uc_mcontext.arm_lr, err); 292 __put_user_error(regs->ARM_pc, &sf->uc.uc_mcontext.arm_pc, err); 293 __put_user_error(regs->ARM_cpsr, &sf->uc.uc_mcontext.arm_cpsr, err); 294 295 __put_user_error(current->thread.trap_no, &sf->uc.uc_mcontext.trap_no, err); 296 __put_user_error(current->thread.error_code, &sf->uc.uc_mcontext.error_code, err); 297 __put_user_error(current->thread.address, &sf->uc.uc_mcontext.fault_address, err); 298 __put_user_error(set->sig[0], &sf->uc.uc_mcontext.oldmask, err); 299 300 err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(*set)); 301 302 aux = (struct aux_sigframe __user *) sf->uc.uc_regspace; 303 #ifdef CONFIG_CRUNCH 304 if (err == 0) 305 err |= preserve_crunch_context(&aux->crunch); 306 #endif 307 #ifdef CONFIG_IWMMXT 308 if (err == 0 && test_thread_flag(TIF_USING_IWMMXT)) 309 err |= preserve_iwmmxt_context(&aux->iwmmxt); 310 #endif 311 #ifdef CONFIG_VFP 312 if (err == 0) 313 err |= preserve_vfp_context(&aux->vfp); 314 #endif 315 __put_user_error(0, &aux->end_magic, err); 316 317 return err; 318 } 319 320 static inline void __user * 321 get_sigframe(struct ksignal *ksig, struct pt_regs *regs, int framesize) 322 { 323 unsigned long sp = sigsp(regs->ARM_sp, ksig); 324 void __user *frame; 325 326 /* 327 * ATPCS B01 mandates 8-byte alignment 328 */ 329 frame = (void __user *)((sp - framesize) & ~7); 330 331 /* 332 * Check that we can actually write to the signal frame. 333 */ 334 if (!access_ok(VERIFY_WRITE, frame, framesize)) 335 frame = NULL; 336 337 return frame; 338 } 339 340 /* 341 * translate the signal 342 */ 343 static inline int map_sig(int sig) 344 { 345 struct thread_info *thread = current_thread_info(); 346 if (sig < 32 && thread->exec_domain && thread->exec_domain->signal_invmap) 347 sig = thread->exec_domain->signal_invmap[sig]; 348 return sig; 349 } 350 351 static int 352 setup_return(struct pt_regs *regs, struct ksignal *ksig, 353 unsigned long __user *rc, void __user *frame) 354 { 355 unsigned long handler = (unsigned long)ksig->ka.sa.sa_handler; 356 unsigned long retcode; 357 int thumb = 0; 358 unsigned long cpsr = regs->ARM_cpsr & ~(PSR_f | PSR_E_BIT); 359 360 cpsr |= PSR_ENDSTATE; 361 362 /* 363 * Maybe we need to deliver a 32-bit signal to a 26-bit task. 364 */ 365 if (ksig->ka.sa.sa_flags & SA_THIRTYTWO) 366 cpsr = (cpsr & ~MODE_MASK) | USR_MODE; 367 368 #ifdef CONFIG_ARM_THUMB 369 if (elf_hwcap & HWCAP_THUMB) { 370 /* 371 * The LSB of the handler determines if we're going to 372 * be using THUMB or ARM mode for this signal handler. 373 */ 374 thumb = handler & 1; 375 376 if (thumb) { 377 cpsr |= PSR_T_BIT; 378 #if __LINUX_ARM_ARCH__ >= 7 379 /* clear the If-Then Thumb-2 execution state */ 380 cpsr &= ~PSR_IT_MASK; 381 #endif 382 } else 383 cpsr &= ~PSR_T_BIT; 384 } 385 #endif 386 387 if (ksig->ka.sa.sa_flags & SA_RESTORER) { 388 retcode = (unsigned long)ksig->ka.sa.sa_restorer; 389 } else { 390 unsigned int idx = thumb << 1; 391 392 if (ksig->ka.sa.sa_flags & SA_SIGINFO) 393 idx += 3; 394 395 if (__put_user(sigreturn_codes[idx], rc) || 396 __put_user(sigreturn_codes[idx+1], rc+1)) 397 return 1; 398 399 if (cpsr & MODE32_BIT) { 400 /* 401 * 32-bit code can use the new high-page 402 * signal return code support. 403 */ 404 retcode = KERN_SIGRETURN_CODE + (idx << 2) + thumb; 405 } else { 406 /* 407 * Ensure that the instruction cache sees 408 * the return code written onto the stack. 409 */ 410 flush_icache_range((unsigned long)rc, 411 (unsigned long)(rc + 2)); 412 413 retcode = ((unsigned long)rc) + thumb; 414 } 415 } 416 417 regs->ARM_r0 = map_sig(ksig->sig); 418 regs->ARM_sp = (unsigned long)frame; 419 regs->ARM_lr = retcode; 420 regs->ARM_pc = handler; 421 regs->ARM_cpsr = cpsr; 422 423 return 0; 424 } 425 426 static int 427 setup_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs) 428 { 429 struct sigframe __user *frame = get_sigframe(ksig, regs, sizeof(*frame)); 430 int err = 0; 431 432 if (!frame) 433 return 1; 434 435 /* 436 * Set uc.uc_flags to a value which sc.trap_no would never have. 437 */ 438 __put_user_error(0x5ac3c35a, &frame->uc.uc_flags, err); 439 440 err |= setup_sigframe(frame, regs, set); 441 if (err == 0) 442 err = setup_return(regs, ksig, frame->retcode, frame); 443 444 return err; 445 } 446 447 static int 448 setup_rt_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs) 449 { 450 struct rt_sigframe __user *frame = get_sigframe(ksig, regs, sizeof(*frame)); 451 int err = 0; 452 453 if (!frame) 454 return 1; 455 456 err |= copy_siginfo_to_user(&frame->info, &ksig->info); 457 458 __put_user_error(0, &frame->sig.uc.uc_flags, err); 459 __put_user_error(NULL, &frame->sig.uc.uc_link, err); 460 461 err |= __save_altstack(&frame->sig.uc.uc_stack, regs->ARM_sp); 462 err |= setup_sigframe(&frame->sig, regs, set); 463 if (err == 0) 464 err = setup_return(regs, ksig, frame->sig.retcode, frame); 465 466 if (err == 0) { 467 /* 468 * For realtime signals we must also set the second and third 469 * arguments for the signal handler. 470 * -- Peter Maydell <pmaydell@chiark.greenend.org.uk> 2000-12-06 471 */ 472 regs->ARM_r1 = (unsigned long)&frame->info; 473 regs->ARM_r2 = (unsigned long)&frame->sig.uc; 474 } 475 476 return err; 477 } 478 479 /* 480 * OK, we're invoking a handler 481 */ 482 static void handle_signal(struct ksignal *ksig, struct pt_regs *regs) 483 { 484 sigset_t *oldset = sigmask_to_save(); 485 int ret; 486 487 /* 488 * Set up the stack frame 489 */ 490 if (ksig->ka.sa.sa_flags & SA_SIGINFO) 491 ret = setup_rt_frame(ksig, oldset, regs); 492 else 493 ret = setup_frame(ksig, oldset, regs); 494 495 /* 496 * Check that the resulting registers are actually sane. 497 */ 498 ret |= !valid_user_regs(regs); 499 500 signal_setup_done(ret, ksig, 0); 501 } 502 503 /* 504 * Note that 'init' is a special process: it doesn't get signals it doesn't 505 * want to handle. Thus you cannot kill init even with a SIGKILL even by 506 * mistake. 507 * 508 * Note that we go through the signals twice: once to check the signals that 509 * the kernel can handle, and then we build all the user-level signal handling 510 * stack-frames in one go after that. 511 */ 512 static int do_signal(struct pt_regs *regs, int syscall) 513 { 514 unsigned int retval = 0, continue_addr = 0, restart_addr = 0; 515 struct ksignal ksig; 516 int restart = 0; 517 518 /* 519 * If we were from a system call, check for system call restarting... 520 */ 521 if (syscall) { 522 continue_addr = regs->ARM_pc; 523 restart_addr = continue_addr - (thumb_mode(regs) ? 2 : 4); 524 retval = regs->ARM_r0; 525 526 /* 527 * Prepare for system call restart. We do this here so that a 528 * debugger will see the already changed PSW. 529 */ 530 switch (retval) { 531 case -ERESTART_RESTARTBLOCK: 532 restart -= 2; 533 case -ERESTARTNOHAND: 534 case -ERESTARTSYS: 535 case -ERESTARTNOINTR: 536 restart++; 537 regs->ARM_r0 = regs->ARM_ORIG_r0; 538 regs->ARM_pc = restart_addr; 539 break; 540 } 541 } 542 543 /* 544 * Get the signal to deliver. When running under ptrace, at this 545 * point the debugger may change all our registers ... 546 */ 547 /* 548 * Depending on the signal settings we may need to revert the 549 * decision to restart the system call. But skip this if a 550 * debugger has chosen to restart at a different PC. 551 */ 552 if (get_signal(&ksig)) { 553 /* handler */ 554 if (unlikely(restart) && regs->ARM_pc == restart_addr) { 555 if (retval == -ERESTARTNOHAND || 556 retval == -ERESTART_RESTARTBLOCK 557 || (retval == -ERESTARTSYS 558 && !(ksig.ka.sa.sa_flags & SA_RESTART))) { 559 regs->ARM_r0 = -EINTR; 560 regs->ARM_pc = continue_addr; 561 } 562 } 563 handle_signal(&ksig, regs); 564 } else { 565 /* no handler */ 566 restore_saved_sigmask(); 567 if (unlikely(restart) && regs->ARM_pc == restart_addr) { 568 regs->ARM_pc = continue_addr; 569 return restart; 570 } 571 } 572 return 0; 573 } 574 575 asmlinkage int 576 do_work_pending(struct pt_regs *regs, unsigned int thread_flags, int syscall) 577 { 578 do { 579 if (likely(thread_flags & _TIF_NEED_RESCHED)) { 580 schedule(); 581 } else { 582 if (unlikely(!user_mode(regs))) 583 return 0; 584 local_irq_enable(); 585 if (thread_flags & _TIF_SIGPENDING) { 586 int restart = do_signal(regs, syscall); 587 if (unlikely(restart)) { 588 /* 589 * Restart without handlers. 590 * Deal with it without leaving 591 * the kernel space. 592 */ 593 return restart; 594 } 595 syscall = 0; 596 } else { 597 clear_thread_flag(TIF_NOTIFY_RESUME); 598 tracehook_notify_resume(regs); 599 } 600 } 601 local_irq_disable(); 602 thread_flags = current_thread_info()->flags; 603 } while (thread_flags & _TIF_WORK_MASK); 604 return 0; 605 } 606