1 /* 2 * Copyright IBM Corp. 1999, 2006 3 * Author(s): Denis Joseph Barrow (djbarrow@de.ibm.com,barrow_dj@yahoo.com) 4 * 5 * Based on Intel version 6 * 7 * Copyright (C) 1991, 1992 Linus Torvalds 8 * 9 * 1997-11-28 Modified for POSIX.1b signals by Richard Henderson 10 */ 11 12 #include <linux/sched.h> 13 #include <linux/mm.h> 14 #include <linux/smp.h> 15 #include <linux/kernel.h> 16 #include <linux/signal.h> 17 #include <linux/errno.h> 18 #include <linux/wait.h> 19 #include <linux/ptrace.h> 20 #include <linux/unistd.h> 21 #include <linux/stddef.h> 22 #include <linux/tty.h> 23 #include <linux/personality.h> 24 #include <linux/binfmts.h> 25 #include <linux/tracehook.h> 26 #include <linux/syscalls.h> 27 #include <linux/compat.h> 28 #include <asm/ucontext.h> 29 #include <asm/uaccess.h> 30 #include <asm/lowcore.h> 31 #include <asm/switch_to.h> 32 #include "entry.h" 33 34 /* 35 * Layout of an old-style signal-frame: 36 * ----------------------------------------- 37 * | save area (_SIGNAL_FRAMESIZE) | 38 * ----------------------------------------- 39 * | struct sigcontext | 40 * | oldmask | 41 * | _sigregs * | 42 * ----------------------------------------- 43 * | _sigregs with | 44 * | _s390_regs_common | 45 * | _s390_fp_regs | 46 * ----------------------------------------- 47 * | int signo | 48 * ----------------------------------------- 49 * | _sigregs_ext with | 50 * | gprs_high 64 byte (opt) | 51 * | vxrs_low 128 byte (opt) | 52 * | vxrs_high 256 byte (opt) | 53 * | reserved 128 byte (opt) | 54 * ----------------------------------------- 55 * | __u16 svc_insn | 56 * ----------------------------------------- 57 * The svc_insn entry with the sigreturn system call opcode does not 58 * have a fixed position and moves if gprs_high or vxrs exist. 59 * Future extensions will be added to _sigregs_ext. 60 */ 61 struct sigframe 62 { 63 __u8 callee_used_stack[__SIGNAL_FRAMESIZE]; 64 struct sigcontext sc; 65 _sigregs sregs; 66 int signo; 67 _sigregs_ext sregs_ext; 68 __u16 svc_insn; /* Offset of svc_insn is NOT fixed! */ 69 }; 70 71 /* 72 * Layout of an rt signal-frame: 73 * ----------------------------------------- 74 * | save area (_SIGNAL_FRAMESIZE) | 75 * ----------------------------------------- 76 * | svc __NR_rt_sigreturn 2 byte | 77 * ----------------------------------------- 78 * | struct siginfo | 79 * ----------------------------------------- 80 * | struct ucontext_extended with | 81 * | unsigned long uc_flags | 82 * | struct ucontext *uc_link | 83 * | stack_t uc_stack | 84 * | _sigregs uc_mcontext with | 85 * | _s390_regs_common | 86 * | _s390_fp_regs | 87 * | sigset_t uc_sigmask | 88 * | _sigregs_ext uc_mcontext_ext | 89 * | gprs_high 64 byte (opt) | 90 * | vxrs_low 128 byte (opt) | 91 * | vxrs_high 256 byte (opt)| 92 * | reserved 128 byte (opt) | 93 * ----------------------------------------- 94 * Future extensions will be added to _sigregs_ext. 95 */ 96 struct rt_sigframe 97 { 98 __u8 callee_used_stack[__SIGNAL_FRAMESIZE]; 99 __u16 svc_insn; 100 struct siginfo info; 101 struct ucontext_extended uc; 102 }; 103 104 /* Store registers needed to create the signal frame */ 105 static void store_sigregs(void) 106 { 107 save_access_regs(current->thread.acrs); 108 save_fp_ctl(¤t->thread.fp_regs.fpc); 109 #ifdef CONFIG_64BIT 110 if (current->thread.vxrs) { 111 int i; 112 113 save_vx_regs(current->thread.vxrs); 114 for (i = 0; i < __NUM_FPRS; i++) 115 current->thread.fp_regs.fprs[i] = 116 *(freg_t *)(current->thread.vxrs + i); 117 } else 118 #endif 119 save_fp_regs(current->thread.fp_regs.fprs); 120 } 121 122 /* Load registers after signal return */ 123 static void load_sigregs(void) 124 { 125 restore_access_regs(current->thread.acrs); 126 /* restore_fp_ctl is done in restore_sigregs */ 127 #ifdef CONFIG_64BIT 128 if (current->thread.vxrs) { 129 int i; 130 131 for (i = 0; i < __NUM_FPRS; i++) 132 *(freg_t *)(current->thread.vxrs + i) = 133 current->thread.fp_regs.fprs[i]; 134 restore_vx_regs(current->thread.vxrs); 135 } else 136 #endif 137 restore_fp_regs(current->thread.fp_regs.fprs); 138 } 139 140 /* Returns non-zero on fault. */ 141 static int save_sigregs(struct pt_regs *regs, _sigregs __user *sregs) 142 { 143 _sigregs user_sregs; 144 145 /* Copy a 'clean' PSW mask to the user to avoid leaking 146 information about whether PER is currently on. */ 147 user_sregs.regs.psw.mask = PSW_USER_BITS | 148 (regs->psw.mask & (PSW_MASK_USER | PSW_MASK_RI)); 149 user_sregs.regs.psw.addr = regs->psw.addr; 150 memcpy(&user_sregs.regs.gprs, ®s->gprs, sizeof(sregs->regs.gprs)); 151 memcpy(&user_sregs.regs.acrs, current->thread.acrs, 152 sizeof(user_sregs.regs.acrs)); 153 memcpy(&user_sregs.fpregs, ¤t->thread.fp_regs, 154 sizeof(user_sregs.fpregs)); 155 if (__copy_to_user(sregs, &user_sregs, sizeof(_sigregs))) 156 return -EFAULT; 157 return 0; 158 } 159 160 static int restore_sigregs(struct pt_regs *regs, _sigregs __user *sregs) 161 { 162 _sigregs user_sregs; 163 164 /* Alwys make any pending restarted system call return -EINTR */ 165 current_thread_info()->restart_block.fn = do_no_restart_syscall; 166 167 if (__copy_from_user(&user_sregs, sregs, sizeof(user_sregs))) 168 return -EFAULT; 169 170 if (!is_ri_task(current) && (user_sregs.regs.psw.mask & PSW_MASK_RI)) 171 return -EINVAL; 172 173 /* Loading the floating-point-control word can fail. Do that first. */ 174 if (restore_fp_ctl(&user_sregs.fpregs.fpc)) 175 return -EINVAL; 176 177 /* Use regs->psw.mask instead of PSW_USER_BITS to preserve PER bit. */ 178 regs->psw.mask = (regs->psw.mask & ~(PSW_MASK_USER | PSW_MASK_RI)) | 179 (user_sregs.regs.psw.mask & (PSW_MASK_USER | PSW_MASK_RI)); 180 /* Check for invalid user address space control. */ 181 if ((regs->psw.mask & PSW_MASK_ASC) == PSW_ASC_HOME) 182 regs->psw.mask = PSW_ASC_PRIMARY | 183 (regs->psw.mask & ~PSW_MASK_ASC); 184 /* Check for invalid amode */ 185 if (regs->psw.mask & PSW_MASK_EA) 186 regs->psw.mask |= PSW_MASK_BA; 187 regs->psw.addr = user_sregs.regs.psw.addr; 188 memcpy(®s->gprs, &user_sregs.regs.gprs, sizeof(sregs->regs.gprs)); 189 memcpy(¤t->thread.acrs, &user_sregs.regs.acrs, 190 sizeof(current->thread.acrs)); 191 192 memcpy(¤t->thread.fp_regs, &user_sregs.fpregs, 193 sizeof(current->thread.fp_regs)); 194 195 clear_pt_regs_flag(regs, PIF_SYSCALL); /* No longer in a system call */ 196 return 0; 197 } 198 199 /* Returns non-zero on fault. */ 200 static int save_sigregs_ext(struct pt_regs *regs, 201 _sigregs_ext __user *sregs_ext) 202 { 203 #ifdef CONFIG_64BIT 204 __u64 vxrs[__NUM_VXRS_LOW]; 205 int i; 206 207 /* Save vector registers to signal stack */ 208 if (current->thread.vxrs) { 209 for (i = 0; i < __NUM_VXRS_LOW; i++) 210 vxrs[i] = *((__u64 *)(current->thread.vxrs + i) + 1); 211 if (__copy_to_user(&sregs_ext->vxrs_low, vxrs, 212 sizeof(sregs_ext->vxrs_low)) || 213 __copy_to_user(&sregs_ext->vxrs_high, 214 current->thread.vxrs + __NUM_VXRS_LOW, 215 sizeof(sregs_ext->vxrs_high))) 216 return -EFAULT; 217 } 218 #endif 219 return 0; 220 } 221 222 static int restore_sigregs_ext(struct pt_regs *regs, 223 _sigregs_ext __user *sregs_ext) 224 { 225 #ifdef CONFIG_64BIT 226 __u64 vxrs[__NUM_VXRS_LOW]; 227 int i; 228 229 /* Restore vector registers from signal stack */ 230 if (current->thread.vxrs) { 231 if (__copy_from_user(vxrs, &sregs_ext->vxrs_low, 232 sizeof(sregs_ext->vxrs_low)) || 233 __copy_from_user(current->thread.vxrs + __NUM_VXRS_LOW, 234 &sregs_ext->vxrs_high, 235 sizeof(sregs_ext->vxrs_high))) 236 return -EFAULT; 237 for (i = 0; i < __NUM_VXRS_LOW; i++) 238 *((__u64 *)(current->thread.vxrs + i) + 1) = vxrs[i]; 239 } 240 #endif 241 return 0; 242 } 243 244 SYSCALL_DEFINE0(sigreturn) 245 { 246 struct pt_regs *regs = task_pt_regs(current); 247 struct sigframe __user *frame = 248 (struct sigframe __user *) regs->gprs[15]; 249 sigset_t set; 250 251 if (__copy_from_user(&set.sig, &frame->sc.oldmask, _SIGMASK_COPY_SIZE)) 252 goto badframe; 253 set_current_blocked(&set); 254 if (restore_sigregs(regs, &frame->sregs)) 255 goto badframe; 256 if (restore_sigregs_ext(regs, &frame->sregs_ext)) 257 goto badframe; 258 load_sigregs(); 259 return regs->gprs[2]; 260 badframe: 261 force_sig(SIGSEGV, current); 262 return 0; 263 } 264 265 SYSCALL_DEFINE0(rt_sigreturn) 266 { 267 struct pt_regs *regs = task_pt_regs(current); 268 struct rt_sigframe __user *frame = 269 (struct rt_sigframe __user *)regs->gprs[15]; 270 sigset_t set; 271 272 if (__copy_from_user(&set.sig, &frame->uc.uc_sigmask, sizeof(set))) 273 goto badframe; 274 set_current_blocked(&set); 275 if (restore_altstack(&frame->uc.uc_stack)) 276 goto badframe; 277 if (restore_sigregs(regs, &frame->uc.uc_mcontext)) 278 goto badframe; 279 if (restore_sigregs_ext(regs, &frame->uc.uc_mcontext_ext)) 280 goto badframe; 281 load_sigregs(); 282 return regs->gprs[2]; 283 badframe: 284 force_sig(SIGSEGV, current); 285 return 0; 286 } 287 288 /* 289 * Determine which stack to use.. 290 */ 291 static inline void __user * 292 get_sigframe(struct k_sigaction *ka, struct pt_regs * regs, size_t frame_size) 293 { 294 unsigned long sp; 295 296 /* Default to using normal stack */ 297 sp = regs->gprs[15]; 298 299 /* Overflow on alternate signal stack gives SIGSEGV. */ 300 if (on_sig_stack(sp) && !on_sig_stack((sp - frame_size) & -8UL)) 301 return (void __user *) -1UL; 302 303 /* This is the X/Open sanctioned signal stack switching. */ 304 if (ka->sa.sa_flags & SA_ONSTACK) { 305 if (! sas_ss_flags(sp)) 306 sp = current->sas_ss_sp + current->sas_ss_size; 307 } 308 309 return (void __user *)((sp - frame_size) & -8ul); 310 } 311 312 static inline int map_signal(int sig) 313 { 314 if (current_thread_info()->exec_domain 315 && current_thread_info()->exec_domain->signal_invmap 316 && sig < 32) 317 return current_thread_info()->exec_domain->signal_invmap[sig]; 318 else 319 return sig; 320 } 321 322 static int setup_frame(int sig, struct k_sigaction *ka, 323 sigset_t *set, struct pt_regs * regs) 324 { 325 struct sigframe __user *frame; 326 struct sigcontext sc; 327 unsigned long restorer; 328 size_t frame_size; 329 330 /* 331 * gprs_high are only present for a 31-bit task running on 332 * a 64-bit kernel (see compat_signal.c) but the space for 333 * gprs_high need to be allocated if vector registers are 334 * included in the signal frame on a 31-bit system. 335 */ 336 frame_size = sizeof(*frame) - sizeof(frame->sregs_ext); 337 if (MACHINE_HAS_VX) 338 frame_size += sizeof(frame->sregs_ext); 339 frame = get_sigframe(ka, regs, frame_size); 340 if (frame == (void __user *) -1UL) 341 return -EFAULT; 342 343 /* Set up backchain. */ 344 if (__put_user(regs->gprs[15], (addr_t __user *) frame)) 345 return -EFAULT; 346 347 /* Create struct sigcontext on the signal stack */ 348 memcpy(&sc.oldmask, &set->sig, _SIGMASK_COPY_SIZE); 349 sc.sregs = (_sigregs __user __force *) &frame->sregs; 350 if (__copy_to_user(&frame->sc, &sc, sizeof(frame->sc))) 351 return -EFAULT; 352 353 /* Store registers needed to create the signal frame */ 354 store_sigregs(); 355 356 /* Create _sigregs on the signal stack */ 357 if (save_sigregs(regs, &frame->sregs)) 358 return -EFAULT; 359 360 /* Place signal number on stack to allow backtrace from handler. */ 361 if (__put_user(regs->gprs[2], (int __user *) &frame->signo)) 362 return -EFAULT; 363 364 /* Create _sigregs_ext on the signal stack */ 365 if (save_sigregs_ext(regs, &frame->sregs_ext)) 366 return -EFAULT; 367 368 /* Set up to return from userspace. If provided, use a stub 369 already in userspace. */ 370 if (ka->sa.sa_flags & SA_RESTORER) { 371 restorer = (unsigned long) ka->sa.sa_restorer | PSW_ADDR_AMODE; 372 } else { 373 /* Signal frame without vector registers are short ! */ 374 __u16 __user *svc = (void *) frame + frame_size - 2; 375 if (__put_user(S390_SYSCALL_OPCODE | __NR_sigreturn, svc)) 376 return -EFAULT; 377 restorer = (unsigned long) svc | PSW_ADDR_AMODE; 378 } 379 380 /* Set up registers for signal handler */ 381 regs->gprs[14] = restorer; 382 regs->gprs[15] = (unsigned long) frame; 383 /* Force default amode and default user address space control. */ 384 regs->psw.mask = PSW_MASK_EA | PSW_MASK_BA | 385 (PSW_USER_BITS & PSW_MASK_ASC) | 386 (regs->psw.mask & ~PSW_MASK_ASC); 387 regs->psw.addr = (unsigned long) ka->sa.sa_handler | PSW_ADDR_AMODE; 388 389 regs->gprs[2] = map_signal(sig); 390 regs->gprs[3] = (unsigned long) &frame->sc; 391 392 /* We forgot to include these in the sigcontext. 393 To avoid breaking binary compatibility, they are passed as args. */ 394 if (sig == SIGSEGV || sig == SIGBUS || sig == SIGILL || 395 sig == SIGTRAP || sig == SIGFPE) { 396 /* set extra registers only for synchronous signals */ 397 regs->gprs[4] = regs->int_code & 127; 398 regs->gprs[5] = regs->int_parm_long; 399 regs->gprs[6] = task_thread_info(current)->last_break; 400 } 401 return 0; 402 } 403 404 static int setup_rt_frame(struct ksignal *ksig, sigset_t *set, 405 struct pt_regs *regs) 406 { 407 struct rt_sigframe __user *frame; 408 unsigned long uc_flags, restorer; 409 size_t frame_size; 410 411 frame_size = sizeof(struct rt_sigframe) - sizeof(_sigregs_ext); 412 /* 413 * gprs_high are only present for a 31-bit task running on 414 * a 64-bit kernel (see compat_signal.c) but the space for 415 * gprs_high need to be allocated if vector registers are 416 * included in the signal frame on a 31-bit system. 417 */ 418 uc_flags = 0; 419 #ifdef CONFIG_64BIT 420 if (MACHINE_HAS_VX) { 421 frame_size += sizeof(_sigregs_ext); 422 if (current->thread.vxrs) 423 uc_flags |= UC_VXRS; 424 } 425 #endif 426 frame = get_sigframe(&ksig->ka, regs, frame_size); 427 if (frame == (void __user *) -1UL) 428 return -EFAULT; 429 430 /* Set up backchain. */ 431 if (__put_user(regs->gprs[15], (addr_t __user *) frame)) 432 return -EFAULT; 433 434 /* Set up to return from userspace. If provided, use a stub 435 already in userspace. */ 436 if (ksig->ka.sa.sa_flags & SA_RESTORER) { 437 restorer = (unsigned long) 438 ksig->ka.sa.sa_restorer | PSW_ADDR_AMODE; 439 } else { 440 __u16 __user *svc = &frame->svc_insn; 441 if (__put_user(S390_SYSCALL_OPCODE | __NR_rt_sigreturn, svc)) 442 return -EFAULT; 443 restorer = (unsigned long) svc | PSW_ADDR_AMODE; 444 } 445 446 /* Create siginfo on the signal stack */ 447 if (copy_siginfo_to_user(&frame->info, &ksig->info)) 448 return -EFAULT; 449 450 /* Store registers needed to create the signal frame */ 451 store_sigregs(); 452 453 /* Create ucontext on the signal stack. */ 454 if (__put_user(uc_flags, &frame->uc.uc_flags) || 455 __put_user(NULL, &frame->uc.uc_link) || 456 __save_altstack(&frame->uc.uc_stack, regs->gprs[15]) || 457 save_sigregs(regs, &frame->uc.uc_mcontext) || 458 __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)) || 459 save_sigregs_ext(regs, &frame->uc.uc_mcontext_ext)) 460 return -EFAULT; 461 462 /* Set up registers for signal handler */ 463 regs->gprs[14] = restorer; 464 regs->gprs[15] = (unsigned long) frame; 465 /* Force default amode and default user address space control. */ 466 regs->psw.mask = PSW_MASK_EA | PSW_MASK_BA | 467 (PSW_USER_BITS & PSW_MASK_ASC) | 468 (regs->psw.mask & ~PSW_MASK_ASC); 469 regs->psw.addr = (unsigned long) ksig->ka.sa.sa_handler | PSW_ADDR_AMODE; 470 471 regs->gprs[2] = map_signal(ksig->sig); 472 regs->gprs[3] = (unsigned long) &frame->info; 473 regs->gprs[4] = (unsigned long) &frame->uc; 474 regs->gprs[5] = task_thread_info(current)->last_break; 475 return 0; 476 } 477 478 static void handle_signal(struct ksignal *ksig, sigset_t *oldset, 479 struct pt_regs *regs) 480 { 481 int ret; 482 483 /* Set up the stack frame */ 484 if (ksig->ka.sa.sa_flags & SA_SIGINFO) 485 ret = setup_rt_frame(ksig, oldset, regs); 486 else 487 ret = setup_frame(ksig->sig, &ksig->ka, oldset, regs); 488 489 signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLE_STEP)); 490 } 491 492 /* 493 * Note that 'init' is a special process: it doesn't get signals it doesn't 494 * want to handle. Thus you cannot kill init even with a SIGKILL even by 495 * mistake. 496 * 497 * Note that we go through the signals twice: once to check the signals that 498 * the kernel can handle, and then we build all the user-level signal handling 499 * stack-frames in one go after that. 500 */ 501 void do_signal(struct pt_regs *regs) 502 { 503 struct ksignal ksig; 504 sigset_t *oldset = sigmask_to_save(); 505 506 /* 507 * Get signal to deliver. When running under ptrace, at this point 508 * the debugger may change all our registers, including the system 509 * call information. 510 */ 511 current_thread_info()->system_call = 512 test_pt_regs_flag(regs, PIF_SYSCALL) ? regs->int_code : 0; 513 514 if (get_signal(&ksig)) { 515 /* Whee! Actually deliver the signal. */ 516 if (current_thread_info()->system_call) { 517 regs->int_code = current_thread_info()->system_call; 518 /* Check for system call restarting. */ 519 switch (regs->gprs[2]) { 520 case -ERESTART_RESTARTBLOCK: 521 case -ERESTARTNOHAND: 522 regs->gprs[2] = -EINTR; 523 break; 524 case -ERESTARTSYS: 525 if (!(ksig.ka.sa.sa_flags & SA_RESTART)) { 526 regs->gprs[2] = -EINTR; 527 break; 528 } 529 /* fallthrough */ 530 case -ERESTARTNOINTR: 531 regs->gprs[2] = regs->orig_gpr2; 532 regs->psw.addr = 533 __rewind_psw(regs->psw, 534 regs->int_code >> 16); 535 break; 536 } 537 } 538 /* No longer in a system call */ 539 clear_pt_regs_flag(regs, PIF_SYSCALL); 540 541 if (is_compat_task()) 542 handle_signal32(&ksig, oldset, regs); 543 else 544 handle_signal(&ksig, oldset, regs); 545 return; 546 } 547 548 /* No handlers present - check for system call restart */ 549 clear_pt_regs_flag(regs, PIF_SYSCALL); 550 if (current_thread_info()->system_call) { 551 regs->int_code = current_thread_info()->system_call; 552 switch (regs->gprs[2]) { 553 case -ERESTART_RESTARTBLOCK: 554 /* Restart with sys_restart_syscall */ 555 regs->int_code = __NR_restart_syscall; 556 /* fallthrough */ 557 case -ERESTARTNOHAND: 558 case -ERESTARTSYS: 559 case -ERESTARTNOINTR: 560 /* Restart system call with magic TIF bit. */ 561 regs->gprs[2] = regs->orig_gpr2; 562 set_pt_regs_flag(regs, PIF_SYSCALL); 563 if (test_thread_flag(TIF_SINGLE_STEP)) 564 clear_pt_regs_flag(regs, PIF_PER_TRAP); 565 break; 566 } 567 } 568 569 /* 570 * If there's no signal to deliver, we just put the saved sigmask back. 571 */ 572 restore_saved_sigmask(); 573 } 574 575 void do_notify_resume(struct pt_regs *regs) 576 { 577 clear_thread_flag(TIF_NOTIFY_RESUME); 578 tracehook_notify_resume(regs); 579 } 580