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 38asmlinkage void ret_from_sys_call(void); 39 40/* 41 * The OSF/1 sigprocmask calling sequence is different from the 42 * C sigprocmask() sequence.. 43 */ 44SYSCALL_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 59SYSCALL_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 90SYSCALL_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 125struct sigframe 126{ 127 struct sigcontext sc; 128 unsigned int retcode[3]; 129}; 130 131struct 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. */ 141extern 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 148static long 149restore_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 err = __get_user(regs->pc, &sc->sc_pc); 154 155 current->restart_block.fn = do_no_restart_syscall; 156 current_thread_info()->status |= TS_SAVED_FP | TS_RESTORE_FP; 157 158 sw->r26 = (unsigned long) ret_from_sys_call; 159 160 err |= __get_user(regs->r0, sc->sc_regs+0); 161 err |= __get_user(regs->r1, sc->sc_regs+1); 162 err |= __get_user(regs->r2, sc->sc_regs+2); 163 err |= __get_user(regs->r3, sc->sc_regs+3); 164 err |= __get_user(regs->r4, sc->sc_regs+4); 165 err |= __get_user(regs->r5, sc->sc_regs+5); 166 err |= __get_user(regs->r6, sc->sc_regs+6); 167 err |= __get_user(regs->r7, sc->sc_regs+7); 168 err |= __get_user(regs->r8, sc->sc_regs+8); 169 err |= __get_user(sw->r9, sc->sc_regs+9); 170 err |= __get_user(sw->r10, sc->sc_regs+10); 171 err |= __get_user(sw->r11, sc->sc_regs+11); 172 err |= __get_user(sw->r12, sc->sc_regs+12); 173 err |= __get_user(sw->r13, sc->sc_regs+13); 174 err |= __get_user(sw->r14, sc->sc_regs+14); 175 err |= __get_user(sw->r15, sc->sc_regs+15); 176 err |= __get_user(regs->r16, sc->sc_regs+16); 177 err |= __get_user(regs->r17, sc->sc_regs+17); 178 err |= __get_user(regs->r18, sc->sc_regs+18); 179 err |= __get_user(regs->r19, sc->sc_regs+19); 180 err |= __get_user(regs->r20, sc->sc_regs+20); 181 err |= __get_user(regs->r21, sc->sc_regs+21); 182 err |= __get_user(regs->r22, sc->sc_regs+22); 183 err |= __get_user(regs->r23, sc->sc_regs+23); 184 err |= __get_user(regs->r24, sc->sc_regs+24); 185 err |= __get_user(regs->r25, sc->sc_regs+25); 186 err |= __get_user(regs->r26, sc->sc_regs+26); 187 err |= __get_user(regs->r27, sc->sc_regs+27); 188 err |= __get_user(regs->r28, sc->sc_regs+28); 189 err |= __get_user(regs->gp, sc->sc_regs+29); 190 err |= __get_user(usp, sc->sc_regs+30); 191 wrusp(usp); 192 193 err |= __copy_from_user(current_thread_info()->fp, 194 sc->sc_fpregs, 31 * 8); 195 err |= __get_user(current_thread_info()->fp[31], &sc->sc_fpcr); 196 197 return err; 198} 199 200/* Note that this syscall is also used by setcontext(3) to install 201 a given sigcontext. This because it's impossible to set *all* 202 registers and transfer control from userland. */ 203 204asmlinkage void 205do_sigreturn(struct sigcontext __user *sc) 206{ 207 struct pt_regs *regs = current_pt_regs(); 208 sigset_t set; 209 210 /* Verify that it's a good sigcontext before using it */ 211 if (!access_ok(sc, sizeof(*sc))) 212 goto give_sigsegv; 213 if (__get_user(set.sig[0], &sc->sc_mask)) 214 goto give_sigsegv; 215 216 set_current_blocked(&set); 217 218 if (restore_sigcontext(sc, regs)) 219 goto give_sigsegv; 220 221 /* Send SIGTRAP if we're single-stepping: */ 222 if (ptrace_cancel_bpt (current)) { 223 send_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *) regs->pc, 224 current); 225 } 226 return; 227 228give_sigsegv: 229 force_sig(SIGSEGV); 230} 231 232asmlinkage void 233do_rt_sigreturn(struct rt_sigframe __user *frame) 234{ 235 struct pt_regs *regs = current_pt_regs(); 236 sigset_t set; 237 238 /* Verify that it's a good ucontext_t before using it */ 239 if (!access_ok(&frame->uc, sizeof(frame->uc))) 240 goto give_sigsegv; 241 if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set))) 242 goto give_sigsegv; 243 244 set_current_blocked(&set); 245 246 if (restore_sigcontext(&frame->uc.uc_mcontext, regs)) 247 goto give_sigsegv; 248 249 /* Send SIGTRAP if we're single-stepping: */ 250 if (ptrace_cancel_bpt (current)) { 251 send_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *) regs->pc, 252 current); 253 } 254 return; 255 256give_sigsegv: 257 force_sig(SIGSEGV); 258} 259 260 261/* 262 * Set up a signal frame. 263 */ 264 265static inline void __user * 266get_sigframe(struct ksignal *ksig, unsigned long sp, size_t frame_size) 267{ 268 return (void __user *)((sigsp(sp, ksig) - frame_size) & -32ul); 269} 270 271static long 272setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs, 273 unsigned long mask, unsigned long sp) 274{ 275 struct switch_stack *sw = (struct switch_stack *)regs - 1; 276 long err = 0; 277 278 err |= __put_user(on_sig_stack((unsigned long)sc), &sc->sc_onstack); 279 err |= __put_user(mask, &sc->sc_mask); 280 err |= __put_user(regs->pc, &sc->sc_pc); 281 err |= __put_user(8, &sc->sc_ps); 282 283 err |= __put_user(regs->r0 , sc->sc_regs+0); 284 err |= __put_user(regs->r1 , sc->sc_regs+1); 285 err |= __put_user(regs->r2 , sc->sc_regs+2); 286 err |= __put_user(regs->r3 , sc->sc_regs+3); 287 err |= __put_user(regs->r4 , sc->sc_regs+4); 288 err |= __put_user(regs->r5 , sc->sc_regs+5); 289 err |= __put_user(regs->r6 , sc->sc_regs+6); 290 err |= __put_user(regs->r7 , sc->sc_regs+7); 291 err |= __put_user(regs->r8 , sc->sc_regs+8); 292 err |= __put_user(sw->r9 , sc->sc_regs+9); 293 err |= __put_user(sw->r10 , sc->sc_regs+10); 294 err |= __put_user(sw->r11 , sc->sc_regs+11); 295 err |= __put_user(sw->r12 , sc->sc_regs+12); 296 err |= __put_user(sw->r13 , sc->sc_regs+13); 297 err |= __put_user(sw->r14 , sc->sc_regs+14); 298 err |= __put_user(sw->r15 , sc->sc_regs+15); 299 err |= __put_user(regs->r16, sc->sc_regs+16); 300 err |= __put_user(regs->r17, sc->sc_regs+17); 301 err |= __put_user(regs->r18, sc->sc_regs+18); 302 err |= __put_user(regs->r19, sc->sc_regs+19); 303 err |= __put_user(regs->r20, sc->sc_regs+20); 304 err |= __put_user(regs->r21, sc->sc_regs+21); 305 err |= __put_user(regs->r22, sc->sc_regs+22); 306 err |= __put_user(regs->r23, sc->sc_regs+23); 307 err |= __put_user(regs->r24, sc->sc_regs+24); 308 err |= __put_user(regs->r25, sc->sc_regs+25); 309 err |= __put_user(regs->r26, sc->sc_regs+26); 310 err |= __put_user(regs->r27, sc->sc_regs+27); 311 err |= __put_user(regs->r28, sc->sc_regs+28); 312 err |= __put_user(regs->gp , sc->sc_regs+29); 313 err |= __put_user(sp, sc->sc_regs+30); 314 err |= __put_user(0, sc->sc_regs+31); 315 316 err |= __copy_to_user(sc->sc_fpregs, 317 current_thread_info()->fp, 31 * 8); 318 err |= __put_user(0, sc->sc_fpregs+31); 319 err |= __put_user(current_thread_info()->fp[31], &sc->sc_fpcr); 320 321 err |= __put_user(regs->trap_a0, &sc->sc_traparg_a0); 322 err |= __put_user(regs->trap_a1, &sc->sc_traparg_a1); 323 err |= __put_user(regs->trap_a2, &sc->sc_traparg_a2); 324 325 return err; 326} 327 328static int 329setup_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs) 330{ 331 unsigned long oldsp, r26, err = 0; 332 struct sigframe __user *frame; 333 334 oldsp = rdusp(); 335 frame = get_sigframe(ksig, oldsp, sizeof(*frame)); 336 if (!access_ok(frame, sizeof(*frame))) 337 return -EFAULT; 338 339 err |= setup_sigcontext(&frame->sc, regs, set->sig[0], oldsp); 340 if (err) 341 return -EFAULT; 342 343 /* Set up to return from userspace. If provided, use a stub 344 already in userspace. */ 345 r26 = (unsigned long) ksig->ka.ka_restorer; 346 if (!r26) { 347 err |= __put_user(INSN_MOV_R30_R16, frame->retcode+0); 348 err |= __put_user(INSN_LDI_R0+__NR_sigreturn, frame->retcode+1); 349 err |= __put_user(INSN_CALLSYS, frame->retcode+2); 350 imb(); 351 r26 = (unsigned long) frame->retcode; 352 } 353 354 /* Check that everything was written properly. */ 355 if (err) 356 return err; 357 358 /* "Return" to the handler */ 359 regs->r26 = r26; 360 regs->r27 = regs->pc = (unsigned long) ksig->ka.sa.sa_handler; 361 regs->r16 = ksig->sig; /* a0: signal number */ 362 regs->r17 = 0; /* a1: exception code */ 363 regs->r18 = (unsigned long) &frame->sc; /* a2: sigcontext pointer */ 364 wrusp((unsigned long) frame); 365 366#if DEBUG_SIG 367 printk("SIG deliver (%s:%d): sp=%p pc=%p ra=%p\n", 368 current->comm, current->pid, frame, regs->pc, regs->r26); 369#endif 370 return 0; 371} 372 373static int 374setup_rt_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs) 375{ 376 unsigned long oldsp, r26, err = 0; 377 struct rt_sigframe __user *frame; 378 379 oldsp = rdusp(); 380 frame = get_sigframe(ksig, oldsp, sizeof(*frame)); 381 if (!access_ok(frame, sizeof(*frame))) 382 return -EFAULT; 383 384 err |= copy_siginfo_to_user(&frame->info, &ksig->info); 385 386 /* Create the ucontext. */ 387 err |= __put_user(0, &frame->uc.uc_flags); 388 err |= __put_user(0, &frame->uc.uc_link); 389 err |= __put_user(set->sig[0], &frame->uc.uc_osf_sigmask); 390 err |= __save_altstack(&frame->uc.uc_stack, oldsp); 391 err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, 392 set->sig[0], oldsp); 393 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)); 394 if (err) 395 return -EFAULT; 396 397 /* Set up to return from userspace. If provided, use a stub 398 already in userspace. */ 399 r26 = (unsigned long) ksig->ka.ka_restorer; 400 if (!r26) { 401 err |= __put_user(INSN_MOV_R30_R16, frame->retcode+0); 402 err |= __put_user(INSN_LDI_R0+__NR_rt_sigreturn, 403 frame->retcode+1); 404 err |= __put_user(INSN_CALLSYS, frame->retcode+2); 405 imb(); 406 r26 = (unsigned long) frame->retcode; 407 } 408 409 if (err) 410 return -EFAULT; 411 412 /* "Return" to the handler */ 413 regs->r26 = r26; 414 regs->r27 = regs->pc = (unsigned long) ksig->ka.sa.sa_handler; 415 regs->r16 = ksig->sig; /* a0: signal number */ 416 regs->r17 = (unsigned long) &frame->info; /* a1: siginfo pointer */ 417 regs->r18 = (unsigned long) &frame->uc; /* a2: ucontext pointer */ 418 wrusp((unsigned long) frame); 419 420#if DEBUG_SIG 421 printk("SIG deliver (%s:%d): sp=%p pc=%p ra=%p\n", 422 current->comm, current->pid, frame, regs->pc, regs->r26); 423#endif 424 425 return 0; 426} 427 428 429/* 430 * OK, we're invoking a handler. 431 */ 432static inline void 433handle_signal(struct ksignal *ksig, struct pt_regs *regs) 434{ 435 sigset_t *oldset = sigmask_to_save(); 436 int ret; 437 438 if (ksig->ka.sa.sa_flags & SA_SIGINFO) 439 ret = setup_rt_frame(ksig, oldset, regs); 440 else 441 ret = setup_frame(ksig, oldset, regs); 442 443 signal_setup_done(ret, ksig, 0); 444} 445 446static inline void 447syscall_restart(unsigned long r0, unsigned long r19, 448 struct pt_regs *regs, struct k_sigaction *ka) 449{ 450 switch (regs->r0) { 451 case ERESTARTSYS: 452 if (!(ka->sa.sa_flags & SA_RESTART)) { 453 case ERESTARTNOHAND: 454 regs->r0 = EINTR; 455 break; 456 } 457 fallthrough; 458 case ERESTARTNOINTR: 459 regs->r0 = r0; /* reset v0 and a3 and replay syscall */ 460 regs->r19 = r19; 461 regs->pc -= 4; 462 break; 463 case ERESTART_RESTARTBLOCK: 464 regs->r0 = EINTR; 465 break; 466 } 467} 468 469 470/* 471 * Note that 'init' is a special process: it doesn't get signals it doesn't 472 * want to handle. Thus you cannot kill init even with a SIGKILL even by 473 * mistake. 474 * 475 * Note that we go through the signals twice: once to check the signals that 476 * the kernel can handle, and then we build all the user-level signal handling 477 * stack-frames in one go after that. 478 * 479 * "r0" and "r19" are the registers we need to restore for system call 480 * restart. "r0" is also used as an indicator whether we can restart at 481 * all (if we get here from anything but a syscall return, it will be 0) 482 */ 483static void 484do_signal(struct pt_regs *regs, unsigned long r0, unsigned long r19) 485{ 486 unsigned long single_stepping = ptrace_cancel_bpt(current); 487 struct ksignal ksig; 488 489 /* This lets the debugger run, ... */ 490 if (get_signal(&ksig)) { 491 /* ... so re-check the single stepping. */ 492 single_stepping |= ptrace_cancel_bpt(current); 493 /* Whee! Actually deliver the signal. */ 494 if (r0) 495 syscall_restart(r0, r19, regs, &ksig.ka); 496 handle_signal(&ksig, regs); 497 } else { 498 single_stepping |= ptrace_cancel_bpt(current); 499 if (r0) { 500 switch (regs->r0) { 501 case ERESTARTNOHAND: 502 case ERESTARTSYS: 503 case ERESTARTNOINTR: 504 /* Reset v0 and a3 and replay syscall. */ 505 regs->r0 = r0; 506 regs->r19 = r19; 507 regs->pc -= 4; 508 break; 509 case ERESTART_RESTARTBLOCK: 510 /* Set v0 to the restart_syscall and replay */ 511 regs->r0 = __NR_restart_syscall; 512 regs->pc -= 4; 513 break; 514 } 515 } 516 restore_saved_sigmask(); 517 } 518 if (single_stepping) 519 ptrace_set_bpt(current); /* re-set breakpoint */ 520} 521 522void 523do_work_pending(struct pt_regs *regs, unsigned long thread_flags, 524 unsigned long r0, unsigned long r19) 525{ 526 do { 527 if (thread_flags & _TIF_NEED_RESCHED) { 528 schedule(); 529 } else { 530 local_irq_enable(); 531 if (thread_flags & (_TIF_SIGPENDING|_TIF_NOTIFY_SIGNAL)) { 532 preempt_disable(); 533 save_fpu(); 534 preempt_enable(); 535 do_signal(regs, r0, r19); 536 r0 = 0; 537 } else { 538 resume_user_mode_work(regs); 539 } 540 } 541 local_irq_disable(); 542 thread_flags = read_thread_flags(); 543 } while (thread_flags & _TIF_WORK_MASK); 544} 545