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