1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Copyright IBM Corp. 1999, 2006 4 * Author(s): Denis Joseph Barrow (djbarrow@de.ibm.com,barrow_dj@yahoo.com) 5 * 6 * Based on Intel version 7 * 8 * Copyright (C) 1991, 1992 Linus Torvalds 9 * 10 * 1997-11-28 Modified for POSIX.1b signals by Richard Henderson 11 */ 12 13 #include <linux/sched.h> 14 #include <linux/sched/task_stack.h> 15 #include <linux/mm.h> 16 #include <linux/smp.h> 17 #include <linux/kernel.h> 18 #include <linux/signal.h> 19 #include <linux/errno.h> 20 #include <linux/wait.h> 21 #include <linux/ptrace.h> 22 #include <linux/unistd.h> 23 #include <linux/stddef.h> 24 #include <linux/tty.h> 25 #include <linux/personality.h> 26 #include <linux/binfmts.h> 27 #include <linux/tracehook.h> 28 #include <linux/syscalls.h> 29 #include <linux/compat.h> 30 #include <asm/ucontext.h> 31 #include <linux/uaccess.h> 32 #include <asm/lowcore.h> 33 #include <asm/switch_to.h> 34 #include "entry.h" 35 36 /* 37 * Layout of an old-style signal-frame: 38 * ----------------------------------------- 39 * | save area (_SIGNAL_FRAMESIZE) | 40 * ----------------------------------------- 41 * | struct sigcontext | 42 * | oldmask | 43 * | _sigregs * | 44 * ----------------------------------------- 45 * | _sigregs with | 46 * | _s390_regs_common | 47 * | _s390_fp_regs | 48 * ----------------------------------------- 49 * | int signo | 50 * ----------------------------------------- 51 * | _sigregs_ext with | 52 * | gprs_high 64 byte (opt) | 53 * | vxrs_low 128 byte (opt) | 54 * | vxrs_high 256 byte (opt) | 55 * | reserved 128 byte (opt) | 56 * ----------------------------------------- 57 * | __u16 svc_insn | 58 * ----------------------------------------- 59 * The svc_insn entry with the sigreturn system call opcode does not 60 * have a fixed position and moves if gprs_high or vxrs exist. 61 * Future extensions will be added to _sigregs_ext. 62 */ 63 struct sigframe 64 { 65 __u8 callee_used_stack[__SIGNAL_FRAMESIZE]; 66 struct sigcontext sc; 67 _sigregs sregs; 68 int signo; 69 _sigregs_ext sregs_ext; 70 __u16 svc_insn; /* Offset of svc_insn is NOT fixed! */ 71 }; 72 73 /* 74 * Layout of an rt signal-frame: 75 * ----------------------------------------- 76 * | save area (_SIGNAL_FRAMESIZE) | 77 * ----------------------------------------- 78 * | svc __NR_rt_sigreturn 2 byte | 79 * ----------------------------------------- 80 * | struct siginfo | 81 * ----------------------------------------- 82 * | struct ucontext_extended with | 83 * | unsigned long uc_flags | 84 * | struct ucontext *uc_link | 85 * | stack_t uc_stack | 86 * | _sigregs uc_mcontext with | 87 * | _s390_regs_common | 88 * | _s390_fp_regs | 89 * | sigset_t uc_sigmask | 90 * | _sigregs_ext uc_mcontext_ext | 91 * | gprs_high 64 byte (opt) | 92 * | vxrs_low 128 byte (opt) | 93 * | vxrs_high 256 byte (opt)| 94 * | reserved 128 byte (opt) | 95 * ----------------------------------------- 96 * Future extensions will be added to _sigregs_ext. 97 */ 98 struct rt_sigframe 99 { 100 __u8 callee_used_stack[__SIGNAL_FRAMESIZE]; 101 __u16 svc_insn; 102 struct siginfo info; 103 struct ucontext_extended uc; 104 }; 105 106 /* Store registers needed to create the signal frame */ 107 static void store_sigregs(void) 108 { 109 save_access_regs(current->thread.acrs); 110 save_fpu_regs(); 111 } 112 113 /* Load registers after signal return */ 114 static void load_sigregs(void) 115 { 116 restore_access_regs(current->thread.acrs); 117 } 118 119 /* Returns non-zero on fault. */ 120 static int save_sigregs(struct pt_regs *regs, _sigregs __user *sregs) 121 { 122 _sigregs user_sregs; 123 124 /* Copy a 'clean' PSW mask to the user to avoid leaking 125 information about whether PER is currently on. */ 126 user_sregs.regs.psw.mask = PSW_USER_BITS | 127 (regs->psw.mask & (PSW_MASK_USER | PSW_MASK_RI)); 128 user_sregs.regs.psw.addr = regs->psw.addr; 129 memcpy(&user_sregs.regs.gprs, ®s->gprs, sizeof(sregs->regs.gprs)); 130 memcpy(&user_sregs.regs.acrs, current->thread.acrs, 131 sizeof(user_sregs.regs.acrs)); 132 fpregs_store(&user_sregs.fpregs, ¤t->thread.fpu); 133 if (__copy_to_user(sregs, &user_sregs, sizeof(_sigregs))) 134 return -EFAULT; 135 return 0; 136 } 137 138 static int restore_sigregs(struct pt_regs *regs, _sigregs __user *sregs) 139 { 140 _sigregs user_sregs; 141 142 /* Alwys make any pending restarted system call return -EINTR */ 143 current->restart_block.fn = do_no_restart_syscall; 144 145 if (__copy_from_user(&user_sregs, sregs, sizeof(user_sregs))) 146 return -EFAULT; 147 148 if (!is_ri_task(current) && (user_sregs.regs.psw.mask & PSW_MASK_RI)) 149 return -EINVAL; 150 151 /* Test the floating-point-control word. */ 152 if (test_fp_ctl(user_sregs.fpregs.fpc)) 153 return -EINVAL; 154 155 /* Use regs->psw.mask instead of PSW_USER_BITS to preserve PER bit. */ 156 regs->psw.mask = (regs->psw.mask & ~(PSW_MASK_USER | PSW_MASK_RI)) | 157 (user_sregs.regs.psw.mask & (PSW_MASK_USER | PSW_MASK_RI)); 158 /* Check for invalid user address space control. */ 159 if ((regs->psw.mask & PSW_MASK_ASC) == PSW_ASC_HOME) 160 regs->psw.mask = PSW_ASC_PRIMARY | 161 (regs->psw.mask & ~PSW_MASK_ASC); 162 /* Check for invalid amode */ 163 if (regs->psw.mask & PSW_MASK_EA) 164 regs->psw.mask |= PSW_MASK_BA; 165 regs->psw.addr = user_sregs.regs.psw.addr; 166 memcpy(®s->gprs, &user_sregs.regs.gprs, sizeof(sregs->regs.gprs)); 167 memcpy(¤t->thread.acrs, &user_sregs.regs.acrs, 168 sizeof(current->thread.acrs)); 169 170 fpregs_load(&user_sregs.fpregs, ¤t->thread.fpu); 171 172 clear_pt_regs_flag(regs, PIF_SYSCALL); /* No longer in a system call */ 173 return 0; 174 } 175 176 /* Returns non-zero on fault. */ 177 static int save_sigregs_ext(struct pt_regs *regs, 178 _sigregs_ext __user *sregs_ext) 179 { 180 __u64 vxrs[__NUM_VXRS_LOW]; 181 int i; 182 183 /* Save vector registers to signal stack */ 184 if (MACHINE_HAS_VX) { 185 for (i = 0; i < __NUM_VXRS_LOW; i++) 186 vxrs[i] = *((__u64 *)(current->thread.fpu.vxrs + i) + 1); 187 if (__copy_to_user(&sregs_ext->vxrs_low, vxrs, 188 sizeof(sregs_ext->vxrs_low)) || 189 __copy_to_user(&sregs_ext->vxrs_high, 190 current->thread.fpu.vxrs + __NUM_VXRS_LOW, 191 sizeof(sregs_ext->vxrs_high))) 192 return -EFAULT; 193 } 194 return 0; 195 } 196 197 static int restore_sigregs_ext(struct pt_regs *regs, 198 _sigregs_ext __user *sregs_ext) 199 { 200 __u64 vxrs[__NUM_VXRS_LOW]; 201 int i; 202 203 /* Restore vector registers from signal stack */ 204 if (MACHINE_HAS_VX) { 205 if (__copy_from_user(vxrs, &sregs_ext->vxrs_low, 206 sizeof(sregs_ext->vxrs_low)) || 207 __copy_from_user(current->thread.fpu.vxrs + __NUM_VXRS_LOW, 208 &sregs_ext->vxrs_high, 209 sizeof(sregs_ext->vxrs_high))) 210 return -EFAULT; 211 for (i = 0; i < __NUM_VXRS_LOW; i++) 212 *((__u64 *)(current->thread.fpu.vxrs + i) + 1) = vxrs[i]; 213 } 214 return 0; 215 } 216 217 SYSCALL_DEFINE0(sigreturn) 218 { 219 struct pt_regs *regs = task_pt_regs(current); 220 struct sigframe __user *frame = 221 (struct sigframe __user *) regs->gprs[15]; 222 sigset_t set; 223 224 if (__copy_from_user(&set.sig, &frame->sc.oldmask, _SIGMASK_COPY_SIZE)) 225 goto badframe; 226 set_current_blocked(&set); 227 save_fpu_regs(); 228 if (restore_sigregs(regs, &frame->sregs)) 229 goto badframe; 230 if (restore_sigregs_ext(regs, &frame->sregs_ext)) 231 goto badframe; 232 load_sigregs(); 233 return regs->gprs[2]; 234 badframe: 235 force_sig(SIGSEGV); 236 return 0; 237 } 238 239 SYSCALL_DEFINE0(rt_sigreturn) 240 { 241 struct pt_regs *regs = task_pt_regs(current); 242 struct rt_sigframe __user *frame = 243 (struct rt_sigframe __user *)regs->gprs[15]; 244 sigset_t set; 245 246 if (__copy_from_user(&set.sig, &frame->uc.uc_sigmask, sizeof(set))) 247 goto badframe; 248 set_current_blocked(&set); 249 if (restore_altstack(&frame->uc.uc_stack)) 250 goto badframe; 251 save_fpu_regs(); 252 if (restore_sigregs(regs, &frame->uc.uc_mcontext)) 253 goto badframe; 254 if (restore_sigregs_ext(regs, &frame->uc.uc_mcontext_ext)) 255 goto badframe; 256 load_sigregs(); 257 return regs->gprs[2]; 258 badframe: 259 force_sig(SIGSEGV); 260 return 0; 261 } 262 263 /* 264 * Determine which stack to use.. 265 */ 266 static inline void __user * 267 get_sigframe(struct k_sigaction *ka, struct pt_regs * regs, size_t frame_size) 268 { 269 unsigned long sp; 270 271 /* Default to using normal stack */ 272 sp = regs->gprs[15]; 273 274 /* Overflow on alternate signal stack gives SIGSEGV. */ 275 if (on_sig_stack(sp) && !on_sig_stack((sp - frame_size) & -8UL)) 276 return (void __user *) -1UL; 277 278 /* This is the X/Open sanctioned signal stack switching. */ 279 if (ka->sa.sa_flags & SA_ONSTACK) { 280 if (! sas_ss_flags(sp)) 281 sp = current->sas_ss_sp + current->sas_ss_size; 282 } 283 284 return (void __user *)((sp - frame_size) & -8ul); 285 } 286 287 static int setup_frame(int sig, struct k_sigaction *ka, 288 sigset_t *set, struct pt_regs * regs) 289 { 290 struct sigframe __user *frame; 291 struct sigcontext sc; 292 unsigned long restorer; 293 size_t frame_size; 294 295 /* 296 * gprs_high are only present for a 31-bit task running on 297 * a 64-bit kernel (see compat_signal.c) but the space for 298 * gprs_high need to be allocated if vector registers are 299 * included in the signal frame on a 31-bit system. 300 */ 301 frame_size = sizeof(*frame) - sizeof(frame->sregs_ext); 302 if (MACHINE_HAS_VX) 303 frame_size += sizeof(frame->sregs_ext); 304 frame = get_sigframe(ka, regs, frame_size); 305 if (frame == (void __user *) -1UL) 306 return -EFAULT; 307 308 /* Set up backchain. */ 309 if (__put_user(regs->gprs[15], (addr_t __user *) frame)) 310 return -EFAULT; 311 312 /* Create struct sigcontext on the signal stack */ 313 memcpy(&sc.oldmask, &set->sig, _SIGMASK_COPY_SIZE); 314 sc.sregs = (_sigregs __user __force *) &frame->sregs; 315 if (__copy_to_user(&frame->sc, &sc, sizeof(frame->sc))) 316 return -EFAULT; 317 318 /* Store registers needed to create the signal frame */ 319 store_sigregs(); 320 321 /* Create _sigregs on the signal stack */ 322 if (save_sigregs(regs, &frame->sregs)) 323 return -EFAULT; 324 325 /* Place signal number on stack to allow backtrace from handler. */ 326 if (__put_user(regs->gprs[2], (int __user *) &frame->signo)) 327 return -EFAULT; 328 329 /* Create _sigregs_ext on the signal stack */ 330 if (save_sigregs_ext(regs, &frame->sregs_ext)) 331 return -EFAULT; 332 333 /* Set up to return from userspace. If provided, use a stub 334 already in userspace. */ 335 if (ka->sa.sa_flags & SA_RESTORER) { 336 restorer = (unsigned long) ka->sa.sa_restorer; 337 } else { 338 /* Signal frame without vector registers are short ! */ 339 __u16 __user *svc = (void __user *) frame + frame_size - 2; 340 if (__put_user(S390_SYSCALL_OPCODE | __NR_sigreturn, svc)) 341 return -EFAULT; 342 restorer = (unsigned long) svc; 343 } 344 345 /* Set up registers for signal handler */ 346 regs->gprs[14] = restorer; 347 regs->gprs[15] = (unsigned long) frame; 348 /* Force default amode and default user address space control. */ 349 regs->psw.mask = PSW_MASK_EA | PSW_MASK_BA | 350 (PSW_USER_BITS & PSW_MASK_ASC) | 351 (regs->psw.mask & ~PSW_MASK_ASC); 352 regs->psw.addr = (unsigned long) ka->sa.sa_handler; 353 354 regs->gprs[2] = sig; 355 regs->gprs[3] = (unsigned long) &frame->sc; 356 357 /* We forgot to include these in the sigcontext. 358 To avoid breaking binary compatibility, they are passed as args. */ 359 if (sig == SIGSEGV || sig == SIGBUS || sig == SIGILL || 360 sig == SIGTRAP || sig == SIGFPE) { 361 /* set extra registers only for synchronous signals */ 362 regs->gprs[4] = regs->int_code & 127; 363 regs->gprs[5] = regs->int_parm_long; 364 regs->gprs[6] = current->thread.last_break; 365 } 366 return 0; 367 } 368 369 static int setup_rt_frame(struct ksignal *ksig, sigset_t *set, 370 struct pt_regs *regs) 371 { 372 struct rt_sigframe __user *frame; 373 unsigned long uc_flags, restorer; 374 size_t frame_size; 375 376 frame_size = sizeof(struct rt_sigframe) - sizeof(_sigregs_ext); 377 /* 378 * gprs_high are only present for a 31-bit task running on 379 * a 64-bit kernel (see compat_signal.c) but the space for 380 * gprs_high need to be allocated if vector registers are 381 * included in the signal frame on a 31-bit system. 382 */ 383 uc_flags = 0; 384 if (MACHINE_HAS_VX) { 385 frame_size += sizeof(_sigregs_ext); 386 uc_flags |= UC_VXRS; 387 } 388 frame = get_sigframe(&ksig->ka, regs, frame_size); 389 if (frame == (void __user *) -1UL) 390 return -EFAULT; 391 392 /* Set up backchain. */ 393 if (__put_user(regs->gprs[15], (addr_t __user *) frame)) 394 return -EFAULT; 395 396 /* Set up to return from userspace. If provided, use a stub 397 already in userspace. */ 398 if (ksig->ka.sa.sa_flags & SA_RESTORER) { 399 restorer = (unsigned long) ksig->ka.sa.sa_restorer; 400 } else { 401 __u16 __user *svc = &frame->svc_insn; 402 if (__put_user(S390_SYSCALL_OPCODE | __NR_rt_sigreturn, svc)) 403 return -EFAULT; 404 restorer = (unsigned long) svc; 405 } 406 407 /* Create siginfo on the signal stack */ 408 if (copy_siginfo_to_user(&frame->info, &ksig->info)) 409 return -EFAULT; 410 411 /* Store registers needed to create the signal frame */ 412 store_sigregs(); 413 414 /* Create ucontext on the signal stack. */ 415 if (__put_user(uc_flags, &frame->uc.uc_flags) || 416 __put_user(NULL, &frame->uc.uc_link) || 417 __save_altstack(&frame->uc.uc_stack, regs->gprs[15]) || 418 save_sigregs(regs, &frame->uc.uc_mcontext) || 419 __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)) || 420 save_sigregs_ext(regs, &frame->uc.uc_mcontext_ext)) 421 return -EFAULT; 422 423 /* Set up registers for signal handler */ 424 regs->gprs[14] = restorer; 425 regs->gprs[15] = (unsigned long) frame; 426 /* Force default amode and default user address space control. */ 427 regs->psw.mask = PSW_MASK_EA | PSW_MASK_BA | 428 (PSW_USER_BITS & PSW_MASK_ASC) | 429 (regs->psw.mask & ~PSW_MASK_ASC); 430 regs->psw.addr = (unsigned long) ksig->ka.sa.sa_handler; 431 432 regs->gprs[2] = ksig->sig; 433 regs->gprs[3] = (unsigned long) &frame->info; 434 regs->gprs[4] = (unsigned long) &frame->uc; 435 regs->gprs[5] = current->thread.last_break; 436 return 0; 437 } 438 439 static void handle_signal(struct ksignal *ksig, sigset_t *oldset, 440 struct pt_regs *regs) 441 { 442 int ret; 443 444 /* Set up the stack frame */ 445 if (ksig->ka.sa.sa_flags & SA_SIGINFO) 446 ret = setup_rt_frame(ksig, oldset, regs); 447 else 448 ret = setup_frame(ksig->sig, &ksig->ka, oldset, regs); 449 450 signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLE_STEP)); 451 } 452 453 /* 454 * Note that 'init' is a special process: it doesn't get signals it doesn't 455 * want to handle. Thus you cannot kill init even with a SIGKILL even by 456 * mistake. 457 * 458 * Note that we go through the signals twice: once to check the signals that 459 * the kernel can handle, and then we build all the user-level signal handling 460 * stack-frames in one go after that. 461 */ 462 void do_signal(struct pt_regs *regs) 463 { 464 struct ksignal ksig; 465 sigset_t *oldset = sigmask_to_save(); 466 467 /* 468 * Get signal to deliver. When running under ptrace, at this point 469 * the debugger may change all our registers, including the system 470 * call information. 471 */ 472 current->thread.system_call = 473 test_pt_regs_flag(regs, PIF_SYSCALL) ? regs->int_code : 0; 474 475 if (get_signal(&ksig)) { 476 /* Whee! Actually deliver the signal. */ 477 if (current->thread.system_call) { 478 regs->int_code = current->thread.system_call; 479 /* Check for system call restarting. */ 480 switch (regs->gprs[2]) { 481 case -ERESTART_RESTARTBLOCK: 482 case -ERESTARTNOHAND: 483 regs->gprs[2] = -EINTR; 484 break; 485 case -ERESTARTSYS: 486 if (!(ksig.ka.sa.sa_flags & SA_RESTART)) { 487 regs->gprs[2] = -EINTR; 488 break; 489 } 490 /* fallthrough */ 491 case -ERESTARTNOINTR: 492 regs->gprs[2] = regs->orig_gpr2; 493 regs->psw.addr = 494 __rewind_psw(regs->psw, 495 regs->int_code >> 16); 496 break; 497 } 498 } 499 /* No longer in a system call */ 500 clear_pt_regs_flag(regs, PIF_SYSCALL); 501 rseq_signal_deliver(&ksig, regs); 502 if (is_compat_task()) 503 handle_signal32(&ksig, oldset, regs); 504 else 505 handle_signal(&ksig, oldset, regs); 506 return; 507 } 508 509 /* No handlers present - check for system call restart */ 510 clear_pt_regs_flag(regs, PIF_SYSCALL); 511 if (current->thread.system_call) { 512 regs->int_code = current->thread.system_call; 513 switch (regs->gprs[2]) { 514 case -ERESTART_RESTARTBLOCK: 515 /* Restart with sys_restart_syscall */ 516 regs->int_code = __NR_restart_syscall; 517 /* fallthrough */ 518 case -ERESTARTNOHAND: 519 case -ERESTARTSYS: 520 case -ERESTARTNOINTR: 521 /* Restart system call with magic TIF bit. */ 522 regs->gprs[2] = regs->orig_gpr2; 523 set_pt_regs_flag(regs, PIF_SYSCALL); 524 if (test_thread_flag(TIF_SINGLE_STEP)) 525 clear_pt_regs_flag(regs, PIF_PER_TRAP); 526 break; 527 } 528 } 529 530 /* 531 * If there's no signal to deliver, we just put the saved sigmask back. 532 */ 533 restore_saved_sigmask(); 534 } 535 536 void do_notify_resume(struct pt_regs *regs) 537 { 538 clear_thread_flag(TIF_NOTIFY_RESUME); 539 tracehook_notify_resume(regs); 540 rseq_handle_notify_resume(NULL, regs); 541 } 542