1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * linux/arch/alpha/kernel/signal.c 4 * 5 * Copyright (C) 1995 Linus Torvalds 6 * 7 * 1997-11-02 Modified for POSIX.1b signals by Richard Henderson 8 */ 9 10 #include <linux/sched/signal.h> 11 #include <linux/sched/task_stack.h> 12 #include <linux/kernel.h> 13 #include <linux/signal.h> 14 #include <linux/errno.h> 15 #include <linux/wait.h> 16 #include <linux/ptrace.h> 17 #include <linux/unistd.h> 18 #include <linux/mm.h> 19 #include <linux/smp.h> 20 #include <linux/stddef.h> 21 #include <linux/tty.h> 22 #include <linux/binfmts.h> 23 #include <linux/bitops.h> 24 #include <linux/syscalls.h> 25 #include <linux/resume_user_mode.h> 26 27 #include <linux/uaccess.h> 28 #include <asm/sigcontext.h> 29 #include <asm/ucontext.h> 30 31 #include "proto.h" 32 33 34 #define DEBUG_SIG 0 35 36 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP))) 37 38 asmlinkage void ret_from_sys_call(void); 39 40 /* 41 * The OSF/1 sigprocmask calling sequence is different from the 42 * C sigprocmask() sequence.. 43 */ 44 45 asmlinkage void alpha_schedule_user_work(void) 46 { 47 local_irq_enable(); 48 schedule(); 49 local_irq_disable(); 50 } 51 52 SYSCALL_DEFINE2(osf_sigprocmask, int, how, unsigned long, newmask) 53 { 54 sigset_t oldmask; 55 sigset_t mask; 56 unsigned long res; 57 58 siginitset(&mask, newmask & _BLOCKABLE); 59 res = sigprocmask(how, &mask, &oldmask); 60 if (!res) { 61 force_successful_syscall_return(); 62 res = oldmask.sig[0]; 63 } 64 return res; 65 } 66 67 SYSCALL_DEFINE3(osf_sigaction, int, sig, 68 const struct osf_sigaction __user *, act, 69 struct osf_sigaction __user *, oact) 70 { 71 struct k_sigaction new_ka, old_ka; 72 int ret; 73 74 if (act) { 75 old_sigset_t mask; 76 if (!access_ok(act, sizeof(*act)) || 77 __get_user(new_ka.sa.sa_handler, &act->sa_handler) || 78 __get_user(new_ka.sa.sa_flags, &act->sa_flags) || 79 __get_user(mask, &act->sa_mask)) 80 return -EFAULT; 81 siginitset(&new_ka.sa.sa_mask, mask); 82 new_ka.ka_restorer = NULL; 83 } 84 85 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL); 86 87 if (!ret && oact) { 88 if (!access_ok(oact, sizeof(*oact)) || 89 __put_user(old_ka.sa.sa_handler, &oact->sa_handler) || 90 __put_user(old_ka.sa.sa_flags, &oact->sa_flags) || 91 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask)) 92 return -EFAULT; 93 } 94 95 return ret; 96 } 97 98 SYSCALL_DEFINE5(rt_sigaction, int, sig, const struct sigaction __user *, act, 99 struct sigaction __user *, oact, 100 size_t, sigsetsize, void __user *, restorer) 101 { 102 struct k_sigaction new_ka, old_ka; 103 int ret; 104 105 /* XXX: Don't preclude handling different sized sigset_t's. */ 106 if (sigsetsize != sizeof(sigset_t)) 107 return -EINVAL; 108 109 if (act) { 110 new_ka.ka_restorer = restorer; 111 if (copy_from_user(&new_ka.sa, act, sizeof(*act))) 112 return -EFAULT; 113 } 114 115 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL); 116 117 if (!ret && oact) { 118 if (copy_to_user(oact, &old_ka.sa, sizeof(*oact))) 119 return -EFAULT; 120 } 121 122 return ret; 123 } 124 125 /* 126 * Do a signal return; undo the signal stack. 127 */ 128 129 #if _NSIG_WORDS > 1 130 # error "Non SA_SIGINFO frame needs rearranging" 131 #endif 132 133 struct sigframe 134 { 135 struct sigcontext sc; 136 unsigned int retcode[3]; 137 }; 138 139 struct rt_sigframe 140 { 141 struct siginfo info; 142 struct ucontext uc; 143 unsigned int retcode[3]; 144 }; 145 146 /* If this changes, userland unwinders that Know Things about our signal 147 frame will break. Do not undertake lightly. It also implies an ABI 148 change wrt the size of siginfo_t, which may cause some pain. */ 149 extern char compile_time_assert 150 [offsetof(struct rt_sigframe, uc.uc_mcontext) == 176 ? 1 : -1]; 151 152 #define INSN_MOV_R30_R16 0x47fe0410 153 #define INSN_LDI_R0 0x201f0000 154 #define INSN_CALLSYS 0x00000083 155 156 static long 157 restore_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs) 158 { 159 unsigned long usp; 160 struct switch_stack *sw = (struct switch_stack *)regs - 1; 161 long err = __get_user(regs->pc, &sc->sc_pc); 162 163 current->restart_block.fn = do_no_restart_syscall; 164 current_thread_info()->status |= TS_SAVED_FP | TS_RESTORE_FP; 165 166 sw->r26 = (unsigned long) ret_from_sys_call; 167 168 err |= __get_user(regs->r0, sc->sc_regs+0); 169 err |= __get_user(regs->r1, sc->sc_regs+1); 170 err |= __get_user(regs->r2, sc->sc_regs+2); 171 err |= __get_user(regs->r3, sc->sc_regs+3); 172 err |= __get_user(regs->r4, sc->sc_regs+4); 173 err |= __get_user(regs->r5, sc->sc_regs+5); 174 err |= __get_user(regs->r6, sc->sc_regs+6); 175 err |= __get_user(regs->r7, sc->sc_regs+7); 176 err |= __get_user(regs->r8, sc->sc_regs+8); 177 err |= __get_user(sw->r9, sc->sc_regs+9); 178 err |= __get_user(sw->r10, sc->sc_regs+10); 179 err |= __get_user(sw->r11, sc->sc_regs+11); 180 err |= __get_user(sw->r12, sc->sc_regs+12); 181 err |= __get_user(sw->r13, sc->sc_regs+13); 182 err |= __get_user(sw->r14, sc->sc_regs+14); 183 err |= __get_user(sw->r15, sc->sc_regs+15); 184 err |= __get_user(regs->r16, sc->sc_regs+16); 185 err |= __get_user(regs->r17, sc->sc_regs+17); 186 err |= __get_user(regs->r18, sc->sc_regs+18); 187 err |= __get_user(regs->r19, sc->sc_regs+19); 188 err |= __get_user(regs->r20, sc->sc_regs+20); 189 err |= __get_user(regs->r21, sc->sc_regs+21); 190 err |= __get_user(regs->r22, sc->sc_regs+22); 191 err |= __get_user(regs->r23, sc->sc_regs+23); 192 err |= __get_user(regs->r24, sc->sc_regs+24); 193 err |= __get_user(regs->r25, sc->sc_regs+25); 194 err |= __get_user(regs->r26, sc->sc_regs+26); 195 err |= __get_user(regs->r27, sc->sc_regs+27); 196 err |= __get_user(regs->r28, sc->sc_regs+28); 197 err |= __get_user(regs->gp, sc->sc_regs+29); 198 err |= __get_user(usp, sc->sc_regs+30); 199 wrusp(usp); 200 201 err |= __copy_from_user(current_thread_info()->fp, 202 sc->sc_fpregs, 31 * 8); 203 err |= __get_user(current_thread_info()->fp[31], &sc->sc_fpcr); 204 205 return err; 206 } 207 208 /* Note that this syscall is also used by setcontext(3) to install 209 a given sigcontext. This because it's impossible to set *all* 210 registers and transfer control from userland. */ 211 212 asmlinkage void 213 do_sigreturn(struct sigcontext __user *sc) 214 { 215 struct pt_regs *regs = current_pt_regs(); 216 sigset_t set; 217 218 /* Verify that it's a good sigcontext before using it */ 219 if (!access_ok(sc, sizeof(*sc))) 220 goto give_sigsegv; 221 if (__get_user(set.sig[0], &sc->sc_mask)) 222 goto give_sigsegv; 223 224 set_current_blocked(&set); 225 226 if (restore_sigcontext(sc, regs)) 227 goto give_sigsegv; 228 229 /* Send SIGTRAP if we're single-stepping: */ 230 if (ptrace_cancel_bpt (current)) { 231 send_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *) regs->pc, 232 current); 233 } 234 return; 235 236 give_sigsegv: 237 force_sig(SIGSEGV); 238 } 239 240 asmlinkage void 241 do_rt_sigreturn(struct rt_sigframe __user *frame) 242 { 243 struct pt_regs *regs = current_pt_regs(); 244 sigset_t set; 245 246 /* Verify that it's a good ucontext_t before using it */ 247 if (!access_ok(&frame->uc, sizeof(frame->uc))) 248 goto give_sigsegv; 249 if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set))) 250 goto give_sigsegv; 251 252 set_current_blocked(&set); 253 254 if (restore_sigcontext(&frame->uc.uc_mcontext, regs)) 255 goto give_sigsegv; 256 257 /* Send SIGTRAP if we're single-stepping: */ 258 if (ptrace_cancel_bpt (current)) { 259 send_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *) regs->pc, 260 current); 261 } 262 return; 263 264 give_sigsegv: 265 force_sig(SIGSEGV); 266 } 267 268 269 /* 270 * Set up a signal frame. 271 */ 272 273 static inline void __user * 274 get_sigframe(struct ksignal *ksig, unsigned long sp, size_t frame_size) 275 { 276 return (void __user *)((sigsp(sp, ksig) - frame_size) & -32ul); 277 } 278 279 static long 280 setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs, 281 unsigned long mask, unsigned long sp) 282 { 283 struct switch_stack *sw = (struct switch_stack *)regs - 1; 284 long err = 0; 285 286 err |= __put_user(on_sig_stack((unsigned long)sc), &sc->sc_onstack); 287 err |= __put_user(mask, &sc->sc_mask); 288 err |= __put_user(regs->pc, &sc->sc_pc); 289 err |= __put_user(8, &sc->sc_ps); 290 291 err |= __put_user(regs->r0 , sc->sc_regs+0); 292 err |= __put_user(regs->r1 , sc->sc_regs+1); 293 err |= __put_user(regs->r2 , sc->sc_regs+2); 294 err |= __put_user(regs->r3 , sc->sc_regs+3); 295 err |= __put_user(regs->r4 , sc->sc_regs+4); 296 err |= __put_user(regs->r5 , sc->sc_regs+5); 297 err |= __put_user(regs->r6 , sc->sc_regs+6); 298 err |= __put_user(regs->r7 , sc->sc_regs+7); 299 err |= __put_user(regs->r8 , sc->sc_regs+8); 300 err |= __put_user(sw->r9 , sc->sc_regs+9); 301 err |= __put_user(sw->r10 , sc->sc_regs+10); 302 err |= __put_user(sw->r11 , sc->sc_regs+11); 303 err |= __put_user(sw->r12 , sc->sc_regs+12); 304 err |= __put_user(sw->r13 , sc->sc_regs+13); 305 err |= __put_user(sw->r14 , sc->sc_regs+14); 306 err |= __put_user(sw->r15 , sc->sc_regs+15); 307 err |= __put_user(regs->r16, sc->sc_regs+16); 308 err |= __put_user(regs->r17, sc->sc_regs+17); 309 err |= __put_user(regs->r18, sc->sc_regs+18); 310 err |= __put_user(regs->r19, sc->sc_regs+19); 311 err |= __put_user(regs->r20, sc->sc_regs+20); 312 err |= __put_user(regs->r21, sc->sc_regs+21); 313 err |= __put_user(regs->r22, sc->sc_regs+22); 314 err |= __put_user(regs->r23, sc->sc_regs+23); 315 err |= __put_user(regs->r24, sc->sc_regs+24); 316 err |= __put_user(regs->r25, sc->sc_regs+25); 317 err |= __put_user(regs->r26, sc->sc_regs+26); 318 err |= __put_user(regs->r27, sc->sc_regs+27); 319 err |= __put_user(regs->r28, sc->sc_regs+28); 320 err |= __put_user(regs->gp , sc->sc_regs+29); 321 err |= __put_user(sp, sc->sc_regs+30); 322 err |= __put_user(0, sc->sc_regs+31); 323 324 err |= __copy_to_user(sc->sc_fpregs, 325 current_thread_info()->fp, 31 * 8); 326 err |= __put_user(0, sc->sc_fpregs+31); 327 err |= __put_user(current_thread_info()->fp[31], &sc->sc_fpcr); 328 329 err |= __put_user(regs->trap_a0, &sc->sc_traparg_a0); 330 err |= __put_user(regs->trap_a1, &sc->sc_traparg_a1); 331 err |= __put_user(regs->trap_a2, &sc->sc_traparg_a2); 332 333 return err; 334 } 335 336 static int 337 setup_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs) 338 { 339 unsigned long oldsp, r26, err = 0; 340 struct sigframe __user *frame; 341 342 oldsp = rdusp(); 343 frame = get_sigframe(ksig, oldsp, sizeof(*frame)); 344 if (!access_ok(frame, sizeof(*frame))) 345 return -EFAULT; 346 347 err |= setup_sigcontext(&frame->sc, regs, set->sig[0], oldsp); 348 if (err) 349 return -EFAULT; 350 351 /* Set up to return from userspace. If provided, use a stub 352 already in userspace. */ 353 r26 = (unsigned long) ksig->ka.ka_restorer; 354 if (!r26) { 355 err |= __put_user(INSN_MOV_R30_R16, frame->retcode+0); 356 err |= __put_user(INSN_LDI_R0+__NR_sigreturn, frame->retcode+1); 357 err |= __put_user(INSN_CALLSYS, frame->retcode+2); 358 imb(); 359 r26 = (unsigned long) frame->retcode; 360 } 361 362 /* Check that everything was written properly. */ 363 if (err) 364 return err; 365 366 /* "Return" to the handler */ 367 regs->r26 = r26; 368 regs->r27 = regs->pc = (unsigned long) ksig->ka.sa.sa_handler; 369 regs->r16 = ksig->sig; /* a0: signal number */ 370 regs->r17 = 0; /* a1: exception code */ 371 regs->r18 = (unsigned long) &frame->sc; /* a2: sigcontext pointer */ 372 wrusp((unsigned long) frame); 373 374 #if DEBUG_SIG 375 printk("SIG deliver (%s:%d): sp=%p pc=%p ra=%p\n", 376 current->comm, current->pid, frame, regs->pc, regs->r26); 377 #endif 378 return 0; 379 } 380 381 static int 382 setup_rt_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs) 383 { 384 unsigned long oldsp, r26, err = 0; 385 struct rt_sigframe __user *frame; 386 387 oldsp = rdusp(); 388 frame = get_sigframe(ksig, oldsp, sizeof(*frame)); 389 if (!access_ok(frame, sizeof(*frame))) 390 return -EFAULT; 391 392 err |= copy_siginfo_to_user(&frame->info, &ksig->info); 393 394 /* Create the ucontext. */ 395 err |= __put_user(0, &frame->uc.uc_flags); 396 err |= __put_user(0, &frame->uc.uc_link); 397 err |= __put_user(set->sig[0], &frame->uc.uc_osf_sigmask); 398 err |= __save_altstack(&frame->uc.uc_stack, oldsp); 399 err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, 400 set->sig[0], oldsp); 401 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)); 402 if (err) 403 return -EFAULT; 404 405 /* Set up to return from userspace. If provided, use a stub 406 already in userspace. */ 407 r26 = (unsigned long) ksig->ka.ka_restorer; 408 if (!r26) { 409 err |= __put_user(INSN_MOV_R30_R16, frame->retcode+0); 410 err |= __put_user(INSN_LDI_R0+__NR_rt_sigreturn, 411 frame->retcode+1); 412 err |= __put_user(INSN_CALLSYS, frame->retcode+2); 413 imb(); 414 r26 = (unsigned long) frame->retcode; 415 } 416 417 if (err) 418 return -EFAULT; 419 420 /* "Return" to the handler */ 421 regs->r26 = r26; 422 regs->r27 = regs->pc = (unsigned long) ksig->ka.sa.sa_handler; 423 regs->r16 = ksig->sig; /* a0: signal number */ 424 regs->r17 = (unsigned long) &frame->info; /* a1: siginfo pointer */ 425 regs->r18 = (unsigned long) &frame->uc; /* a2: ucontext pointer */ 426 wrusp((unsigned long) frame); 427 428 #if DEBUG_SIG 429 printk("SIG deliver (%s:%d): sp=%p pc=%p ra=%p\n", 430 current->comm, current->pid, frame, regs->pc, regs->r26); 431 #endif 432 433 return 0; 434 } 435 436 437 /* 438 * OK, we're invoking a handler. 439 */ 440 static inline void 441 handle_signal(struct ksignal *ksig, struct pt_regs *regs) 442 { 443 sigset_t *oldset = sigmask_to_save(); 444 int ret; 445 446 if (ksig->ka.sa.sa_flags & SA_SIGINFO) 447 ret = setup_rt_frame(ksig, oldset, regs); 448 else 449 ret = setup_frame(ksig, oldset, regs); 450 451 signal_setup_done(ret, ksig, 0); 452 } 453 454 static inline void 455 syscall_restart(unsigned long r0, unsigned long r19, 456 struct pt_regs *regs, struct k_sigaction *ka) 457 { 458 switch (regs->r0) { 459 case ERESTARTSYS: 460 if (!(ka->sa.sa_flags & SA_RESTART)) { 461 case ERESTARTNOHAND: 462 regs->r0 = EINTR; 463 break; 464 } 465 fallthrough; 466 case ERESTARTNOINTR: 467 regs->r0 = r0; /* reset v0 and a3 and replay syscall */ 468 regs->r19 = r19; 469 regs->pc -= 4; 470 break; 471 case ERESTART_RESTARTBLOCK: 472 regs->r0 = EINTR; 473 break; 474 } 475 } 476 477 478 /* 479 * Note that 'init' is a special process: it doesn't get signals it doesn't 480 * want to handle. Thus you cannot kill init even with a SIGKILL even by 481 * mistake. 482 * 483 * Note that we go through the signals twice: once to check the signals that 484 * the kernel can handle, and then we build all the user-level signal handling 485 * stack-frames in one go after that. 486 * 487 * "r0" and "r19" are the registers we need to restore for system call 488 * restart. "r0" is also used as an indicator whether we can restart at 489 * all (if we get here from anything but a syscall return, it will be 0) 490 */ 491 static void 492 do_signal(struct pt_regs *regs, unsigned long r0, unsigned long r19) 493 { 494 unsigned long single_stepping = ptrace_cancel_bpt(current); 495 struct ksignal ksig; 496 497 /* This lets the debugger run, ... */ 498 if (get_signal(&ksig)) { 499 /* ... so re-check the single stepping. */ 500 single_stepping |= ptrace_cancel_bpt(current); 501 /* Whee! Actually deliver the signal. */ 502 if (r0) 503 syscall_restart(r0, r19, regs, &ksig.ka); 504 handle_signal(&ksig, regs); 505 } else { 506 single_stepping |= ptrace_cancel_bpt(current); 507 if (r0) { 508 switch (regs->r0) { 509 case ERESTARTNOHAND: 510 case ERESTARTSYS: 511 case ERESTARTNOINTR: 512 /* Reset v0 and a3 and replay syscall. */ 513 regs->r0 = r0; 514 regs->r19 = r19; 515 regs->pc -= 4; 516 break; 517 case ERESTART_RESTARTBLOCK: 518 /* Set v0 to the restart_syscall and replay */ 519 regs->r0 = __NR_restart_syscall; 520 regs->pc -= 4; 521 break; 522 } 523 } 524 restore_saved_sigmask(); 525 } 526 if (single_stepping) 527 ptrace_set_bpt(current); /* re-set breakpoint */ 528 } 529 530 void 531 do_work_pending(struct pt_regs *regs, unsigned long thread_flags, 532 unsigned long r0, unsigned long r19) 533 { 534 do { 535 if (thread_flags & _TIF_NEED_RESCHED) { 536 local_irq_enable(); 537 schedule(); 538 } else { 539 local_irq_enable(); 540 if (thread_flags & (_TIF_SIGPENDING|_TIF_NOTIFY_SIGNAL)) { 541 preempt_disable(); 542 save_fpu(); 543 preempt_enable(); 544 do_signal(regs, r0, r19); 545 r0 = 0; 546 } else { 547 resume_user_mode_work(regs); 548 } 549 } 550 local_irq_disable(); 551 thread_flags = read_thread_flags(); 552 } while (thread_flags & _TIF_WORK_MASK); 553 } 554