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