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