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_fpu_regs(); 109 } 110 111 /* Load registers after signal return */ 112 static void load_sigregs(void) 113 { 114 restore_access_regs(current->thread.acrs); 115 } 116 117 /* Returns non-zero on fault. */ 118 static int save_sigregs(struct pt_regs *regs, _sigregs __user *sregs) 119 { 120 _sigregs user_sregs; 121 122 /* Copy a 'clean' PSW mask to the user to avoid leaking 123 information about whether PER is currently on. */ 124 user_sregs.regs.psw.mask = PSW_USER_BITS | 125 (regs->psw.mask & (PSW_MASK_USER | PSW_MASK_RI)); 126 user_sregs.regs.psw.addr = regs->psw.addr; 127 memcpy(&user_sregs.regs.gprs, ®s->gprs, sizeof(sregs->regs.gprs)); 128 memcpy(&user_sregs.regs.acrs, current->thread.acrs, 129 sizeof(user_sregs.regs.acrs)); 130 fpregs_store(&user_sregs.fpregs, ¤t->thread.fpu); 131 if (__copy_to_user(sregs, &user_sregs, sizeof(_sigregs))) 132 return -EFAULT; 133 return 0; 134 } 135 136 static int restore_sigregs(struct pt_regs *regs, _sigregs __user *sregs) 137 { 138 _sigregs user_sregs; 139 140 /* Alwys make any pending restarted system call return -EINTR */ 141 current->restart_block.fn = do_no_restart_syscall; 142 143 if (__copy_from_user(&user_sregs, sregs, sizeof(user_sregs))) 144 return -EFAULT; 145 146 if (!is_ri_task(current) && (user_sregs.regs.psw.mask & PSW_MASK_RI)) 147 return -EINVAL; 148 149 /* Test the floating-point-control word. */ 150 if (test_fp_ctl(user_sregs.fpregs.fpc)) 151 return -EINVAL; 152 153 /* Use regs->psw.mask instead of PSW_USER_BITS to preserve PER bit. */ 154 regs->psw.mask = (regs->psw.mask & ~(PSW_MASK_USER | PSW_MASK_RI)) | 155 (user_sregs.regs.psw.mask & (PSW_MASK_USER | PSW_MASK_RI)); 156 /* Check for invalid user address space control. */ 157 if ((regs->psw.mask & PSW_MASK_ASC) == PSW_ASC_HOME) 158 regs->psw.mask = PSW_ASC_PRIMARY | 159 (regs->psw.mask & ~PSW_MASK_ASC); 160 /* Check for invalid amode */ 161 if (regs->psw.mask & PSW_MASK_EA) 162 regs->psw.mask |= PSW_MASK_BA; 163 regs->psw.addr = user_sregs.regs.psw.addr; 164 memcpy(®s->gprs, &user_sregs.regs.gprs, sizeof(sregs->regs.gprs)); 165 memcpy(¤t->thread.acrs, &user_sregs.regs.acrs, 166 sizeof(current->thread.acrs)); 167 168 fpregs_load(&user_sregs.fpregs, ¤t->thread.fpu); 169 170 clear_pt_regs_flag(regs, PIF_SYSCALL); /* No longer in a system call */ 171 return 0; 172 } 173 174 /* Returns non-zero on fault. */ 175 static int save_sigregs_ext(struct pt_regs *regs, 176 _sigregs_ext __user *sregs_ext) 177 { 178 __u64 vxrs[__NUM_VXRS_LOW]; 179 int i; 180 181 /* Save vector registers to signal stack */ 182 if (is_vx_task(current)) { 183 for (i = 0; i < __NUM_VXRS_LOW; i++) 184 vxrs[i] = *((__u64 *)(current->thread.fpu.vxrs + i) + 1); 185 if (__copy_to_user(&sregs_ext->vxrs_low, vxrs, 186 sizeof(sregs_ext->vxrs_low)) || 187 __copy_to_user(&sregs_ext->vxrs_high, 188 current->thread.fpu.vxrs + __NUM_VXRS_LOW, 189 sizeof(sregs_ext->vxrs_high))) 190 return -EFAULT; 191 } 192 return 0; 193 } 194 195 static int restore_sigregs_ext(struct pt_regs *regs, 196 _sigregs_ext __user *sregs_ext) 197 { 198 __u64 vxrs[__NUM_VXRS_LOW]; 199 int i; 200 201 /* Restore vector registers from signal stack */ 202 if (is_vx_task(current)) { 203 if (__copy_from_user(vxrs, &sregs_ext->vxrs_low, 204 sizeof(sregs_ext->vxrs_low)) || 205 __copy_from_user(current->thread.fpu.vxrs + __NUM_VXRS_LOW, 206 &sregs_ext->vxrs_high, 207 sizeof(sregs_ext->vxrs_high))) 208 return -EFAULT; 209 for (i = 0; i < __NUM_VXRS_LOW; i++) 210 *((__u64 *)(current->thread.fpu.vxrs + i) + 1) = vxrs[i]; 211 } 212 return 0; 213 } 214 215 SYSCALL_DEFINE0(sigreturn) 216 { 217 struct pt_regs *regs = task_pt_regs(current); 218 struct sigframe __user *frame = 219 (struct sigframe __user *) regs->gprs[15]; 220 sigset_t set; 221 222 if (__copy_from_user(&set.sig, &frame->sc.oldmask, _SIGMASK_COPY_SIZE)) 223 goto badframe; 224 set_current_blocked(&set); 225 save_fpu_regs(); 226 if (restore_sigregs(regs, &frame->sregs)) 227 goto badframe; 228 if (restore_sigregs_ext(regs, &frame->sregs_ext)) 229 goto badframe; 230 load_sigregs(); 231 return regs->gprs[2]; 232 badframe: 233 force_sig(SIGSEGV, current); 234 return 0; 235 } 236 237 SYSCALL_DEFINE0(rt_sigreturn) 238 { 239 struct pt_regs *regs = task_pt_regs(current); 240 struct rt_sigframe __user *frame = 241 (struct rt_sigframe __user *)regs->gprs[15]; 242 sigset_t set; 243 244 if (__copy_from_user(&set.sig, &frame->uc.uc_sigmask, sizeof(set))) 245 goto badframe; 246 set_current_blocked(&set); 247 if (restore_altstack(&frame->uc.uc_stack)) 248 goto badframe; 249 save_fpu_regs(); 250 if (restore_sigregs(regs, &frame->uc.uc_mcontext)) 251 goto badframe; 252 if (restore_sigregs_ext(regs, &frame->uc.uc_mcontext_ext)) 253 goto badframe; 254 load_sigregs(); 255 return regs->gprs[2]; 256 badframe: 257 force_sig(SIGSEGV, current); 258 return 0; 259 } 260 261 /* 262 * Determine which stack to use.. 263 */ 264 static inline void __user * 265 get_sigframe(struct k_sigaction *ka, struct pt_regs * regs, size_t frame_size) 266 { 267 unsigned long sp; 268 269 /* Default to using normal stack */ 270 sp = regs->gprs[15]; 271 272 /* Overflow on alternate signal stack gives SIGSEGV. */ 273 if (on_sig_stack(sp) && !on_sig_stack((sp - frame_size) & -8UL)) 274 return (void __user *) -1UL; 275 276 /* This is the X/Open sanctioned signal stack switching. */ 277 if (ka->sa.sa_flags & SA_ONSTACK) { 278 if (! sas_ss_flags(sp)) 279 sp = current->sas_ss_sp + current->sas_ss_size; 280 } 281 282 return (void __user *)((sp - frame_size) & -8ul); 283 } 284 285 static int setup_frame(int sig, struct k_sigaction *ka, 286 sigset_t *set, struct pt_regs * regs) 287 { 288 struct sigframe __user *frame; 289 struct sigcontext sc; 290 unsigned long restorer; 291 size_t frame_size; 292 293 /* 294 * gprs_high are only present for a 31-bit task running on 295 * a 64-bit kernel (see compat_signal.c) but the space for 296 * gprs_high need to be allocated if vector registers are 297 * included in the signal frame on a 31-bit system. 298 */ 299 frame_size = sizeof(*frame) - sizeof(frame->sregs_ext); 300 if (MACHINE_HAS_VX) 301 frame_size += sizeof(frame->sregs_ext); 302 frame = get_sigframe(ka, regs, frame_size); 303 if (frame == (void __user *) -1UL) 304 return -EFAULT; 305 306 /* Set up backchain. */ 307 if (__put_user(regs->gprs[15], (addr_t __user *) frame)) 308 return -EFAULT; 309 310 /* Create struct sigcontext on the signal stack */ 311 memcpy(&sc.oldmask, &set->sig, _SIGMASK_COPY_SIZE); 312 sc.sregs = (_sigregs __user __force *) &frame->sregs; 313 if (__copy_to_user(&frame->sc, &sc, sizeof(frame->sc))) 314 return -EFAULT; 315 316 /* Store registers needed to create the signal frame */ 317 store_sigregs(); 318 319 /* Create _sigregs on the signal stack */ 320 if (save_sigregs(regs, &frame->sregs)) 321 return -EFAULT; 322 323 /* Place signal number on stack to allow backtrace from handler. */ 324 if (__put_user(regs->gprs[2], (int __user *) &frame->signo)) 325 return -EFAULT; 326 327 /* Create _sigregs_ext on the signal stack */ 328 if (save_sigregs_ext(regs, &frame->sregs_ext)) 329 return -EFAULT; 330 331 /* Set up to return from userspace. If provided, use a stub 332 already in userspace. */ 333 if (ka->sa.sa_flags & SA_RESTORER) { 334 restorer = (unsigned long) ka->sa.sa_restorer | PSW_ADDR_AMODE; 335 } else { 336 /* Signal frame without vector registers are short ! */ 337 __u16 __user *svc = (void __user *) frame + frame_size - 2; 338 if (__put_user(S390_SYSCALL_OPCODE | __NR_sigreturn, svc)) 339 return -EFAULT; 340 restorer = (unsigned long) svc | PSW_ADDR_AMODE; 341 } 342 343 /* Set up registers for signal handler */ 344 regs->gprs[14] = restorer; 345 regs->gprs[15] = (unsigned long) frame; 346 /* Force default amode and default user address space control. */ 347 regs->psw.mask = PSW_MASK_EA | PSW_MASK_BA | 348 (PSW_USER_BITS & PSW_MASK_ASC) | 349 (regs->psw.mask & ~PSW_MASK_ASC); 350 regs->psw.addr = (unsigned long) ka->sa.sa_handler | PSW_ADDR_AMODE; 351 352 regs->gprs[2] = sig; 353 regs->gprs[3] = (unsigned long) &frame->sc; 354 355 /* We forgot to include these in the sigcontext. 356 To avoid breaking binary compatibility, they are passed as args. */ 357 if (sig == SIGSEGV || sig == SIGBUS || sig == SIGILL || 358 sig == SIGTRAP || sig == SIGFPE) { 359 /* set extra registers only for synchronous signals */ 360 regs->gprs[4] = regs->int_code & 127; 361 regs->gprs[5] = regs->int_parm_long; 362 regs->gprs[6] = task_thread_info(current)->last_break; 363 } 364 return 0; 365 } 366 367 static int setup_rt_frame(struct ksignal *ksig, sigset_t *set, 368 struct pt_regs *regs) 369 { 370 struct rt_sigframe __user *frame; 371 unsigned long uc_flags, restorer; 372 size_t frame_size; 373 374 frame_size = sizeof(struct rt_sigframe) - sizeof(_sigregs_ext); 375 /* 376 * gprs_high are only present for a 31-bit task running on 377 * a 64-bit kernel (see compat_signal.c) but the space for 378 * gprs_high need to be allocated if vector registers are 379 * included in the signal frame on a 31-bit system. 380 */ 381 uc_flags = 0; 382 if (MACHINE_HAS_VX) { 383 frame_size += sizeof(_sigregs_ext); 384 if (is_vx_task(current)) 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) 399 ksig->ka.sa.sa_restorer | PSW_ADDR_AMODE; 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 | PSW_ADDR_AMODE; 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 | PSW_ADDR_AMODE; 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] = task_thread_info(current)->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_info()->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_info()->system_call) { 478 regs->int_code = current_thread_info()->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); 501 502 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_info()->system_call) { 512 regs->int_code = current_thread_info()->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 } 541