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/freezer.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/ucontext.h> 20 #include <asm/unistd.h> 21 22 #include "ptrace.h" 23 #include "signal.h" 24 25 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP))) 26 27 /* 28 * For ARM syscalls, we encode the syscall number into the instruction. 29 */ 30 #define SWI_SYS_SIGRETURN (0xef000000|(__NR_sigreturn)|(__NR_OABI_SYSCALL_BASE)) 31 #define SWI_SYS_RT_SIGRETURN (0xef000000|(__NR_rt_sigreturn)|(__NR_OABI_SYSCALL_BASE)) 32 #define SWI_SYS_RESTART (0xef000000|__NR_restart_syscall|__NR_OABI_SYSCALL_BASE) 33 34 /* 35 * With EABI, the syscall number has to be loaded into r7. 36 */ 37 #define MOV_R7_NR_SIGRETURN (0xe3a07000 | (__NR_sigreturn - __NR_SYSCALL_BASE)) 38 #define MOV_R7_NR_RT_SIGRETURN (0xe3a07000 | (__NR_rt_sigreturn - __NR_SYSCALL_BASE)) 39 40 /* 41 * For Thumb syscalls, we pass the syscall number via r7. We therefore 42 * need two 16-bit instructions. 43 */ 44 #define SWI_THUMB_SIGRETURN (0xdf00 << 16 | 0x2700 | (__NR_sigreturn - __NR_SYSCALL_BASE)) 45 #define SWI_THUMB_RT_SIGRETURN (0xdf00 << 16 | 0x2700 | (__NR_rt_sigreturn - __NR_SYSCALL_BASE)) 46 47 const unsigned long sigreturn_codes[7] = { 48 MOV_R7_NR_SIGRETURN, SWI_SYS_SIGRETURN, SWI_THUMB_SIGRETURN, 49 MOV_R7_NR_RT_SIGRETURN, SWI_SYS_RT_SIGRETURN, SWI_THUMB_RT_SIGRETURN, 50 }; 51 52 /* 53 * Either we support OABI only, or we have EABI with the OABI 54 * compat layer enabled. In the later case we don't know if 55 * user space is EABI or not, and if not we must not clobber r7. 56 * Always using the OABI syscall solves that issue and works for 57 * all those cases. 58 */ 59 const unsigned long syscall_restart_code[2] = { 60 SWI_SYS_RESTART, /* swi __NR_restart_syscall */ 61 0xe49df004, /* ldr pc, [sp], #4 */ 62 }; 63 64 /* 65 * atomically swap in the new signal mask, and wait for a signal. 66 */ 67 asmlinkage int sys_sigsuspend(int restart, unsigned long oldmask, old_sigset_t mask) 68 { 69 mask &= _BLOCKABLE; 70 spin_lock_irq(¤t->sighand->siglock); 71 current->saved_sigmask = current->blocked; 72 siginitset(¤t->blocked, mask); 73 recalc_sigpending(); 74 spin_unlock_irq(¤t->sighand->siglock); 75 76 current->state = TASK_INTERRUPTIBLE; 77 schedule(); 78 set_restore_sigmask(); 79 return -ERESTARTNOHAND; 80 } 81 82 asmlinkage int 83 sys_sigaction(int sig, const struct old_sigaction __user *act, 84 struct old_sigaction __user *oact) 85 { 86 struct k_sigaction new_ka, old_ka; 87 int ret; 88 89 if (act) { 90 old_sigset_t mask; 91 if (!access_ok(VERIFY_READ, act, sizeof(*act)) || 92 __get_user(new_ka.sa.sa_handler, &act->sa_handler) || 93 __get_user(new_ka.sa.sa_restorer, &act->sa_restorer)) 94 return -EFAULT; 95 __get_user(new_ka.sa.sa_flags, &act->sa_flags); 96 __get_user(mask, &act->sa_mask); 97 siginitset(&new_ka.sa.sa_mask, mask); 98 } 99 100 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL); 101 102 if (!ret && oact) { 103 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) || 104 __put_user(old_ka.sa.sa_handler, &oact->sa_handler) || 105 __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer)) 106 return -EFAULT; 107 __put_user(old_ka.sa.sa_flags, &oact->sa_flags); 108 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask); 109 } 110 111 return ret; 112 } 113 114 #ifdef CONFIG_CRUNCH 115 static int preserve_crunch_context(struct crunch_sigframe __user *frame) 116 { 117 char kbuf[sizeof(*frame) + 8]; 118 struct crunch_sigframe *kframe; 119 120 /* the crunch context must be 64 bit aligned */ 121 kframe = (struct crunch_sigframe *)((unsigned long)(kbuf + 8) & ~7); 122 kframe->magic = CRUNCH_MAGIC; 123 kframe->size = CRUNCH_STORAGE_SIZE; 124 crunch_task_copy(current_thread_info(), &kframe->storage); 125 return __copy_to_user(frame, kframe, sizeof(*frame)); 126 } 127 128 static int restore_crunch_context(struct crunch_sigframe __user *frame) 129 { 130 char kbuf[sizeof(*frame) + 8]; 131 struct crunch_sigframe *kframe; 132 133 /* the crunch context must be 64 bit aligned */ 134 kframe = (struct crunch_sigframe *)((unsigned long)(kbuf + 8) & ~7); 135 if (__copy_from_user(kframe, frame, sizeof(*frame))) 136 return -1; 137 if (kframe->magic != CRUNCH_MAGIC || 138 kframe->size != CRUNCH_STORAGE_SIZE) 139 return -1; 140 crunch_task_restore(current_thread_info(), &kframe->storage); 141 return 0; 142 } 143 #endif 144 145 #ifdef CONFIG_IWMMXT 146 147 static int preserve_iwmmxt_context(struct iwmmxt_sigframe *frame) 148 { 149 char kbuf[sizeof(*frame) + 8]; 150 struct iwmmxt_sigframe *kframe; 151 152 /* the iWMMXt context must be 64 bit aligned */ 153 kframe = (struct iwmmxt_sigframe *)((unsigned long)(kbuf + 8) & ~7); 154 kframe->magic = IWMMXT_MAGIC; 155 kframe->size = IWMMXT_STORAGE_SIZE; 156 iwmmxt_task_copy(current_thread_info(), &kframe->storage); 157 return __copy_to_user(frame, kframe, sizeof(*frame)); 158 } 159 160 static int restore_iwmmxt_context(struct iwmmxt_sigframe *frame) 161 { 162 char kbuf[sizeof(*frame) + 8]; 163 struct iwmmxt_sigframe *kframe; 164 165 /* the iWMMXt context must be 64 bit aligned */ 166 kframe = (struct iwmmxt_sigframe *)((unsigned long)(kbuf + 8) & ~7); 167 if (__copy_from_user(kframe, frame, sizeof(*frame))) 168 return -1; 169 if (kframe->magic != IWMMXT_MAGIC || 170 kframe->size != IWMMXT_STORAGE_SIZE) 171 return -1; 172 iwmmxt_task_restore(current_thread_info(), &kframe->storage); 173 return 0; 174 } 175 176 #endif 177 178 /* 179 * Do a signal return; undo the signal stack. These are aligned to 64-bit. 180 */ 181 struct sigframe { 182 struct ucontext uc; 183 unsigned long retcode[2]; 184 }; 185 186 struct rt_sigframe { 187 struct siginfo info; 188 struct sigframe sig; 189 }; 190 191 static int restore_sigframe(struct pt_regs *regs, struct sigframe __user *sf) 192 { 193 struct aux_sigframe __user *aux; 194 sigset_t set; 195 int err; 196 197 err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set)); 198 if (err == 0) { 199 sigdelsetmask(&set, ~_BLOCKABLE); 200 spin_lock_irq(¤t->sighand->siglock); 201 current->blocked = set; 202 recalc_sigpending(); 203 spin_unlock_irq(¤t->sighand->siglock); 204 } 205 206 __get_user_error(regs->ARM_r0, &sf->uc.uc_mcontext.arm_r0, err); 207 __get_user_error(regs->ARM_r1, &sf->uc.uc_mcontext.arm_r1, err); 208 __get_user_error(regs->ARM_r2, &sf->uc.uc_mcontext.arm_r2, err); 209 __get_user_error(regs->ARM_r3, &sf->uc.uc_mcontext.arm_r3, err); 210 __get_user_error(regs->ARM_r4, &sf->uc.uc_mcontext.arm_r4, err); 211 __get_user_error(regs->ARM_r5, &sf->uc.uc_mcontext.arm_r5, err); 212 __get_user_error(regs->ARM_r6, &sf->uc.uc_mcontext.arm_r6, err); 213 __get_user_error(regs->ARM_r7, &sf->uc.uc_mcontext.arm_r7, err); 214 __get_user_error(regs->ARM_r8, &sf->uc.uc_mcontext.arm_r8, err); 215 __get_user_error(regs->ARM_r9, &sf->uc.uc_mcontext.arm_r9, err); 216 __get_user_error(regs->ARM_r10, &sf->uc.uc_mcontext.arm_r10, err); 217 __get_user_error(regs->ARM_fp, &sf->uc.uc_mcontext.arm_fp, err); 218 __get_user_error(regs->ARM_ip, &sf->uc.uc_mcontext.arm_ip, err); 219 __get_user_error(regs->ARM_sp, &sf->uc.uc_mcontext.arm_sp, err); 220 __get_user_error(regs->ARM_lr, &sf->uc.uc_mcontext.arm_lr, err); 221 __get_user_error(regs->ARM_pc, &sf->uc.uc_mcontext.arm_pc, err); 222 __get_user_error(regs->ARM_cpsr, &sf->uc.uc_mcontext.arm_cpsr, err); 223 224 err |= !valid_user_regs(regs); 225 226 aux = (struct aux_sigframe __user *) sf->uc.uc_regspace; 227 #ifdef CONFIG_CRUNCH 228 if (err == 0) 229 err |= restore_crunch_context(&aux->crunch); 230 #endif 231 #ifdef CONFIG_IWMMXT 232 if (err == 0 && test_thread_flag(TIF_USING_IWMMXT)) 233 err |= restore_iwmmxt_context(&aux->iwmmxt); 234 #endif 235 #ifdef CONFIG_VFP 236 // if (err == 0) 237 // err |= vfp_restore_state(&sf->aux.vfp); 238 #endif 239 240 return err; 241 } 242 243 asmlinkage int sys_sigreturn(struct pt_regs *regs) 244 { 245 struct sigframe __user *frame; 246 247 /* Always make any pending restarted system calls return -EINTR */ 248 current_thread_info()->restart_block.fn = do_no_restart_syscall; 249 250 /* 251 * Since we stacked the signal on a 64-bit boundary, 252 * then 'sp' should be word aligned here. If it's 253 * not, then the user is trying to mess with us. 254 */ 255 if (regs->ARM_sp & 7) 256 goto badframe; 257 258 frame = (struct sigframe __user *)regs->ARM_sp; 259 260 if (!access_ok(VERIFY_READ, frame, sizeof (*frame))) 261 goto badframe; 262 263 if (restore_sigframe(regs, frame)) 264 goto badframe; 265 266 single_step_trap(current); 267 268 return regs->ARM_r0; 269 270 badframe: 271 force_sig(SIGSEGV, current); 272 return 0; 273 } 274 275 asmlinkage int sys_rt_sigreturn(struct pt_regs *regs) 276 { 277 struct rt_sigframe __user *frame; 278 279 /* Always make any pending restarted system calls return -EINTR */ 280 current_thread_info()->restart_block.fn = do_no_restart_syscall; 281 282 /* 283 * Since we stacked the signal on a 64-bit boundary, 284 * then 'sp' should be word aligned here. If it's 285 * not, then the user is trying to mess with us. 286 */ 287 if (regs->ARM_sp & 7) 288 goto badframe; 289 290 frame = (struct rt_sigframe __user *)regs->ARM_sp; 291 292 if (!access_ok(VERIFY_READ, frame, sizeof (*frame))) 293 goto badframe; 294 295 if (restore_sigframe(regs, &frame->sig)) 296 goto badframe; 297 298 if (do_sigaltstack(&frame->sig.uc.uc_stack, NULL, regs->ARM_sp) == -EFAULT) 299 goto badframe; 300 301 single_step_trap(current); 302 303 return regs->ARM_r0; 304 305 badframe: 306 force_sig(SIGSEGV, current); 307 return 0; 308 } 309 310 static int 311 setup_sigframe(struct sigframe __user *sf, struct pt_regs *regs, sigset_t *set) 312 { 313 struct aux_sigframe __user *aux; 314 int err = 0; 315 316 __put_user_error(regs->ARM_r0, &sf->uc.uc_mcontext.arm_r0, err); 317 __put_user_error(regs->ARM_r1, &sf->uc.uc_mcontext.arm_r1, err); 318 __put_user_error(regs->ARM_r2, &sf->uc.uc_mcontext.arm_r2, err); 319 __put_user_error(regs->ARM_r3, &sf->uc.uc_mcontext.arm_r3, err); 320 __put_user_error(regs->ARM_r4, &sf->uc.uc_mcontext.arm_r4, err); 321 __put_user_error(regs->ARM_r5, &sf->uc.uc_mcontext.arm_r5, err); 322 __put_user_error(regs->ARM_r6, &sf->uc.uc_mcontext.arm_r6, err); 323 __put_user_error(regs->ARM_r7, &sf->uc.uc_mcontext.arm_r7, err); 324 __put_user_error(regs->ARM_r8, &sf->uc.uc_mcontext.arm_r8, err); 325 __put_user_error(regs->ARM_r9, &sf->uc.uc_mcontext.arm_r9, err); 326 __put_user_error(regs->ARM_r10, &sf->uc.uc_mcontext.arm_r10, err); 327 __put_user_error(regs->ARM_fp, &sf->uc.uc_mcontext.arm_fp, err); 328 __put_user_error(regs->ARM_ip, &sf->uc.uc_mcontext.arm_ip, err); 329 __put_user_error(regs->ARM_sp, &sf->uc.uc_mcontext.arm_sp, err); 330 __put_user_error(regs->ARM_lr, &sf->uc.uc_mcontext.arm_lr, err); 331 __put_user_error(regs->ARM_pc, &sf->uc.uc_mcontext.arm_pc, err); 332 __put_user_error(regs->ARM_cpsr, &sf->uc.uc_mcontext.arm_cpsr, err); 333 334 __put_user_error(current->thread.trap_no, &sf->uc.uc_mcontext.trap_no, err); 335 __put_user_error(current->thread.error_code, &sf->uc.uc_mcontext.error_code, err); 336 __put_user_error(current->thread.address, &sf->uc.uc_mcontext.fault_address, err); 337 __put_user_error(set->sig[0], &sf->uc.uc_mcontext.oldmask, err); 338 339 err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(*set)); 340 341 aux = (struct aux_sigframe __user *) sf->uc.uc_regspace; 342 #ifdef CONFIG_CRUNCH 343 if (err == 0) 344 err |= preserve_crunch_context(&aux->crunch); 345 #endif 346 #ifdef CONFIG_IWMMXT 347 if (err == 0 && test_thread_flag(TIF_USING_IWMMXT)) 348 err |= preserve_iwmmxt_context(&aux->iwmmxt); 349 #endif 350 #ifdef CONFIG_VFP 351 // if (err == 0) 352 // err |= vfp_save_state(&sf->aux.vfp); 353 #endif 354 __put_user_error(0, &aux->end_magic, err); 355 356 return err; 357 } 358 359 static inline void __user * 360 get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, int framesize) 361 { 362 unsigned long sp = regs->ARM_sp; 363 void __user *frame; 364 365 /* 366 * This is the X/Open sanctioned signal stack switching. 367 */ 368 if ((ka->sa.sa_flags & SA_ONSTACK) && !sas_ss_flags(sp)) 369 sp = current->sas_ss_sp + current->sas_ss_size; 370 371 /* 372 * ATPCS B01 mandates 8-byte alignment 373 */ 374 frame = (void __user *)((sp - framesize) & ~7); 375 376 /* 377 * Check that we can actually write to the signal frame. 378 */ 379 if (!access_ok(VERIFY_WRITE, frame, framesize)) 380 frame = NULL; 381 382 return frame; 383 } 384 385 static int 386 setup_return(struct pt_regs *regs, struct k_sigaction *ka, 387 unsigned long __user *rc, void __user *frame, int usig) 388 { 389 unsigned long handler = (unsigned long)ka->sa.sa_handler; 390 unsigned long retcode; 391 int thumb = 0; 392 unsigned long cpsr = regs->ARM_cpsr & ~PSR_f; 393 394 /* 395 * Maybe we need to deliver a 32-bit signal to a 26-bit task. 396 */ 397 if (ka->sa.sa_flags & SA_THIRTYTWO) 398 cpsr = (cpsr & ~MODE_MASK) | USR_MODE; 399 400 #ifdef CONFIG_ARM_THUMB 401 if (elf_hwcap & HWCAP_THUMB) { 402 /* 403 * The LSB of the handler determines if we're going to 404 * be using THUMB or ARM mode for this signal handler. 405 */ 406 thumb = handler & 1; 407 408 if (thumb) { 409 cpsr |= PSR_T_BIT; 410 #if __LINUX_ARM_ARCH__ >= 7 411 /* clear the If-Then Thumb-2 execution state */ 412 cpsr &= ~PSR_IT_MASK; 413 #endif 414 } else 415 cpsr &= ~PSR_T_BIT; 416 } 417 #endif 418 419 if (ka->sa.sa_flags & SA_RESTORER) { 420 retcode = (unsigned long)ka->sa.sa_restorer; 421 } else { 422 unsigned int idx = thumb << 1; 423 424 if (ka->sa.sa_flags & SA_SIGINFO) 425 idx += 3; 426 427 if (__put_user(sigreturn_codes[idx], rc) || 428 __put_user(sigreturn_codes[idx+1], rc+1)) 429 return 1; 430 431 if (cpsr & MODE32_BIT) { 432 /* 433 * 32-bit code can use the new high-page 434 * signal return code support. 435 */ 436 retcode = KERN_SIGRETURN_CODE + (idx << 2) + thumb; 437 } else { 438 /* 439 * Ensure that the instruction cache sees 440 * the return code written onto the stack. 441 */ 442 flush_icache_range((unsigned long)rc, 443 (unsigned long)(rc + 2)); 444 445 retcode = ((unsigned long)rc) + thumb; 446 } 447 } 448 449 regs->ARM_r0 = usig; 450 regs->ARM_sp = (unsigned long)frame; 451 regs->ARM_lr = retcode; 452 regs->ARM_pc = handler; 453 regs->ARM_cpsr = cpsr; 454 455 return 0; 456 } 457 458 static int 459 setup_frame(int usig, struct k_sigaction *ka, sigset_t *set, struct pt_regs *regs) 460 { 461 struct sigframe __user *frame = get_sigframe(ka, regs, sizeof(*frame)); 462 int err = 0; 463 464 if (!frame) 465 return 1; 466 467 /* 468 * Set uc.uc_flags to a value which sc.trap_no would never have. 469 */ 470 __put_user_error(0x5ac3c35a, &frame->uc.uc_flags, err); 471 472 err |= setup_sigframe(frame, regs, set); 473 if (err == 0) 474 err = setup_return(regs, ka, frame->retcode, frame, usig); 475 476 return err; 477 } 478 479 static int 480 setup_rt_frame(int usig, struct k_sigaction *ka, siginfo_t *info, 481 sigset_t *set, struct pt_regs *regs) 482 { 483 struct rt_sigframe __user *frame = get_sigframe(ka, regs, sizeof(*frame)); 484 stack_t stack; 485 int err = 0; 486 487 if (!frame) 488 return 1; 489 490 err |= copy_siginfo_to_user(&frame->info, info); 491 492 __put_user_error(0, &frame->sig.uc.uc_flags, err); 493 __put_user_error(NULL, &frame->sig.uc.uc_link, err); 494 495 memset(&stack, 0, sizeof(stack)); 496 stack.ss_sp = (void __user *)current->sas_ss_sp; 497 stack.ss_flags = sas_ss_flags(regs->ARM_sp); 498 stack.ss_size = current->sas_ss_size; 499 err |= __copy_to_user(&frame->sig.uc.uc_stack, &stack, sizeof(stack)); 500 501 err |= setup_sigframe(&frame->sig, regs, set); 502 if (err == 0) 503 err = setup_return(regs, ka, frame->sig.retcode, frame, usig); 504 505 if (err == 0) { 506 /* 507 * For realtime signals we must also set the second and third 508 * arguments for the signal handler. 509 * -- Peter Maydell <pmaydell@chiark.greenend.org.uk> 2000-12-06 510 */ 511 regs->ARM_r1 = (unsigned long)&frame->info; 512 regs->ARM_r2 = (unsigned long)&frame->sig.uc; 513 } 514 515 return err; 516 } 517 518 static inline void setup_syscall_restart(struct pt_regs *regs) 519 { 520 regs->ARM_r0 = regs->ARM_ORIG_r0; 521 regs->ARM_pc -= thumb_mode(regs) ? 2 : 4; 522 } 523 524 /* 525 * OK, we're invoking a handler 526 */ 527 static int 528 handle_signal(unsigned long sig, struct k_sigaction *ka, 529 siginfo_t *info, sigset_t *oldset, 530 struct pt_regs * regs, int syscall) 531 { 532 struct thread_info *thread = current_thread_info(); 533 struct task_struct *tsk = current; 534 int usig = sig; 535 int ret; 536 537 /* 538 * If we were from a system call, check for system call restarting... 539 */ 540 if (syscall) { 541 switch (regs->ARM_r0) { 542 case -ERESTART_RESTARTBLOCK: 543 case -ERESTARTNOHAND: 544 regs->ARM_r0 = -EINTR; 545 break; 546 case -ERESTARTSYS: 547 if (!(ka->sa.sa_flags & SA_RESTART)) { 548 regs->ARM_r0 = -EINTR; 549 break; 550 } 551 /* fallthrough */ 552 case -ERESTARTNOINTR: 553 setup_syscall_restart(regs); 554 } 555 } 556 557 /* 558 * translate the signal 559 */ 560 if (usig < 32 && thread->exec_domain && thread->exec_domain->signal_invmap) 561 usig = thread->exec_domain->signal_invmap[usig]; 562 563 /* 564 * Set up the stack frame 565 */ 566 if (ka->sa.sa_flags & SA_SIGINFO) 567 ret = setup_rt_frame(usig, ka, info, oldset, regs); 568 else 569 ret = setup_frame(usig, ka, oldset, regs); 570 571 /* 572 * Check that the resulting registers are actually sane. 573 */ 574 ret |= !valid_user_regs(regs); 575 576 if (ret != 0) { 577 force_sigsegv(sig, tsk); 578 return ret; 579 } 580 581 /* 582 * Block the signal if we were successful. 583 */ 584 spin_lock_irq(&tsk->sighand->siglock); 585 sigorsets(&tsk->blocked, &tsk->blocked, 586 &ka->sa.sa_mask); 587 if (!(ka->sa.sa_flags & SA_NODEFER)) 588 sigaddset(&tsk->blocked, sig); 589 recalc_sigpending(); 590 spin_unlock_irq(&tsk->sighand->siglock); 591 592 return 0; 593 } 594 595 /* 596 * Note that 'init' is a special process: it doesn't get signals it doesn't 597 * want to handle. Thus you cannot kill init even with a SIGKILL even by 598 * mistake. 599 * 600 * Note that we go through the signals twice: once to check the signals that 601 * the kernel can handle, and then we build all the user-level signal handling 602 * stack-frames in one go after that. 603 */ 604 static void do_signal(struct pt_regs *regs, int syscall) 605 { 606 struct k_sigaction ka; 607 siginfo_t info; 608 int signr; 609 610 /* 611 * We want the common case to go fast, which 612 * is why we may in certain cases get here from 613 * kernel mode. Just return without doing anything 614 * if so. 615 */ 616 if (!user_mode(regs)) 617 return; 618 619 if (try_to_freeze()) 620 goto no_signal; 621 622 single_step_clear(current); 623 624 signr = get_signal_to_deliver(&info, &ka, regs, NULL); 625 if (signr > 0) { 626 sigset_t *oldset; 627 628 if (test_thread_flag(TIF_RESTORE_SIGMASK)) 629 oldset = ¤t->saved_sigmask; 630 else 631 oldset = ¤t->blocked; 632 if (handle_signal(signr, &ka, &info, oldset, regs, syscall) == 0) { 633 /* 634 * A signal was successfully delivered; the saved 635 * sigmask will have been stored in the signal frame, 636 * and will be restored by sigreturn, so we can simply 637 * clear the TIF_RESTORE_SIGMASK flag. 638 */ 639 if (test_thread_flag(TIF_RESTORE_SIGMASK)) 640 clear_thread_flag(TIF_RESTORE_SIGMASK); 641 } 642 single_step_set(current); 643 return; 644 } 645 646 no_signal: 647 /* 648 * No signal to deliver to the process - restart the syscall. 649 */ 650 if (syscall) { 651 if (regs->ARM_r0 == -ERESTART_RESTARTBLOCK) { 652 if (thumb_mode(regs)) { 653 regs->ARM_r7 = __NR_restart_syscall - __NR_SYSCALL_BASE; 654 regs->ARM_pc -= 2; 655 } else { 656 #if defined(CONFIG_AEABI) && !defined(CONFIG_OABI_COMPAT) 657 regs->ARM_r7 = __NR_restart_syscall; 658 regs->ARM_pc -= 4; 659 #else 660 u32 __user *usp; 661 662 regs->ARM_sp -= 4; 663 usp = (u32 __user *)regs->ARM_sp; 664 665 if (put_user(regs->ARM_pc, usp) == 0) { 666 regs->ARM_pc = KERN_RESTART_CODE; 667 } else { 668 regs->ARM_sp += 4; 669 force_sigsegv(0, current); 670 } 671 #endif 672 } 673 } 674 if (regs->ARM_r0 == -ERESTARTNOHAND || 675 regs->ARM_r0 == -ERESTARTSYS || 676 regs->ARM_r0 == -ERESTARTNOINTR) { 677 setup_syscall_restart(regs); 678 } 679 680 /* If there's no signal to deliver, we just put the saved sigmask 681 * back. 682 */ 683 if (test_thread_flag(TIF_RESTORE_SIGMASK)) { 684 clear_thread_flag(TIF_RESTORE_SIGMASK); 685 sigprocmask(SIG_SETMASK, ¤t->saved_sigmask, NULL); 686 } 687 } 688 single_step_set(current); 689 } 690 691 asmlinkage void 692 do_notify_resume(struct pt_regs *regs, unsigned int thread_flags, int syscall) 693 { 694 if (thread_flags & _TIF_SIGPENDING) 695 do_signal(regs, syscall); 696 697 if (thread_flags & _TIF_NOTIFY_RESUME) { 698 clear_thread_flag(TIF_NOTIFY_RESUME); 699 tracehook_notify_resume(regs); 700 if (current->replacement_session_keyring) 701 key_replace_session_keyring(); 702 } 703 } 704