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 typedef struct 35 { 36 __u8 callee_used_stack[__SIGNAL_FRAMESIZE]; 37 struct sigcontext sc; 38 _sigregs sregs; 39 int signo; 40 __u8 retcode[S390_SYSCALL_SIZE]; 41 } sigframe; 42 43 typedef struct 44 { 45 __u8 callee_used_stack[__SIGNAL_FRAMESIZE]; 46 __u8 retcode[S390_SYSCALL_SIZE]; 47 struct siginfo info; 48 struct ucontext uc; 49 } rt_sigframe; 50 51 /* 52 * Atomically swap in the new signal mask, and wait for a signal. 53 */ 54 SYSCALL_DEFINE3(sigsuspend, int, history0, int, history1, old_sigset_t, mask) 55 { 56 sigset_t blocked; 57 siginitset(&blocked, mask); 58 return sigsuspend(&blocked); 59 } 60 61 SYSCALL_DEFINE3(sigaction, int, sig, const struct old_sigaction __user *, act, 62 struct old_sigaction __user *, oact) 63 { 64 struct k_sigaction new_ka, old_ka; 65 int ret; 66 67 if (act) { 68 old_sigset_t mask; 69 if (!access_ok(VERIFY_READ, act, sizeof(*act)) || 70 __get_user(new_ka.sa.sa_handler, &act->sa_handler) || 71 __get_user(new_ka.sa.sa_restorer, &act->sa_restorer) || 72 __get_user(new_ka.sa.sa_flags, &act->sa_flags) || 73 __get_user(mask, &act->sa_mask)) 74 return -EFAULT; 75 siginitset(&new_ka.sa.sa_mask, mask); 76 } 77 78 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL); 79 80 if (!ret && oact) { 81 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) || 82 __put_user(old_ka.sa.sa_handler, &oact->sa_handler) || 83 __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer) || 84 __put_user(old_ka.sa.sa_flags, &oact->sa_flags) || 85 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask)) 86 return -EFAULT; 87 } 88 89 return ret; 90 } 91 92 SYSCALL_DEFINE2(sigaltstack, const stack_t __user *, uss, 93 stack_t __user *, uoss) 94 { 95 struct pt_regs *regs = task_pt_regs(current); 96 return do_sigaltstack(uss, uoss, regs->gprs[15]); 97 } 98 99 /* Returns non-zero on fault. */ 100 static int save_sigregs(struct pt_regs *regs, _sigregs __user *sregs) 101 { 102 _sigregs user_sregs; 103 104 save_access_regs(current->thread.acrs); 105 106 /* Copy a 'clean' PSW mask to the user to avoid leaking 107 information about whether PER is currently on. */ 108 user_sregs.regs.psw.mask = psw_user_bits | 109 (regs->psw.mask & PSW_MASK_USER); 110 user_sregs.regs.psw.addr = regs->psw.addr; 111 memcpy(&user_sregs.regs.gprs, ®s->gprs, sizeof(sregs->regs.gprs)); 112 memcpy(&user_sregs.regs.acrs, current->thread.acrs, 113 sizeof(sregs->regs.acrs)); 114 /* 115 * We have to store the fp registers to current->thread.fp_regs 116 * to merge them with the emulated registers. 117 */ 118 save_fp_regs(¤t->thread.fp_regs); 119 memcpy(&user_sregs.fpregs, ¤t->thread.fp_regs, 120 sizeof(s390_fp_regs)); 121 return __copy_to_user(sregs, &user_sregs, sizeof(_sigregs)); 122 } 123 124 /* Returns positive number on error */ 125 static int restore_sigregs(struct pt_regs *regs, _sigregs __user *sregs) 126 { 127 int err; 128 _sigregs user_sregs; 129 130 /* Alwys make any pending restarted system call return -EINTR */ 131 current_thread_info()->restart_block.fn = do_no_restart_syscall; 132 133 err = __copy_from_user(&user_sregs, sregs, sizeof(_sigregs)); 134 if (err) 135 return err; 136 /* Use regs->psw.mask instead of psw_user_bits to preserve PER bit. */ 137 regs->psw.mask = (regs->psw.mask & ~PSW_MASK_USER) | 138 (user_sregs.regs.psw.mask & PSW_MASK_USER); 139 /* Check for invalid amode */ 140 if (regs->psw.mask & PSW_MASK_EA) 141 regs->psw.mask |= PSW_MASK_BA; 142 regs->psw.addr = user_sregs.regs.psw.addr; 143 memcpy(®s->gprs, &user_sregs.regs.gprs, sizeof(sregs->regs.gprs)); 144 memcpy(¤t->thread.acrs, &user_sregs.regs.acrs, 145 sizeof(sregs->regs.acrs)); 146 restore_access_regs(current->thread.acrs); 147 148 memcpy(¤t->thread.fp_regs, &user_sregs.fpregs, 149 sizeof(s390_fp_regs)); 150 current->thread.fp_regs.fpc &= FPC_VALID_MASK; 151 152 restore_fp_regs(¤t->thread.fp_regs); 153 clear_thread_flag(TIF_SYSCALL); /* No longer in a system call */ 154 return 0; 155 } 156 157 SYSCALL_DEFINE0(sigreturn) 158 { 159 struct pt_regs *regs = task_pt_regs(current); 160 sigframe __user *frame = (sigframe __user *)regs->gprs[15]; 161 sigset_t set; 162 163 if (!access_ok(VERIFY_READ, frame, sizeof(*frame))) 164 goto badframe; 165 if (__copy_from_user(&set.sig, &frame->sc.oldmask, _SIGMASK_COPY_SIZE)) 166 goto badframe; 167 set_current_blocked(&set); 168 if (restore_sigregs(regs, &frame->sregs)) 169 goto badframe; 170 return regs->gprs[2]; 171 badframe: 172 force_sig(SIGSEGV, current); 173 return 0; 174 } 175 176 SYSCALL_DEFINE0(rt_sigreturn) 177 { 178 struct pt_regs *regs = task_pt_regs(current); 179 rt_sigframe __user *frame = (rt_sigframe __user *)regs->gprs[15]; 180 sigset_t set; 181 182 if (!access_ok(VERIFY_READ, frame, sizeof(*frame))) 183 goto badframe; 184 if (__copy_from_user(&set.sig, &frame->uc.uc_sigmask, sizeof(set))) 185 goto badframe; 186 set_current_blocked(&set); 187 if (restore_sigregs(regs, &frame->uc.uc_mcontext)) 188 goto badframe; 189 if (do_sigaltstack(&frame->uc.uc_stack, NULL, 190 regs->gprs[15]) == -EFAULT) 191 goto badframe; 192 return regs->gprs[2]; 193 badframe: 194 force_sig(SIGSEGV, current); 195 return 0; 196 } 197 198 /* 199 * Set up a signal frame. 200 */ 201 202 203 /* 204 * Determine which stack to use.. 205 */ 206 static inline void __user * 207 get_sigframe(struct k_sigaction *ka, struct pt_regs * regs, size_t frame_size) 208 { 209 unsigned long sp; 210 211 /* Default to using normal stack */ 212 sp = regs->gprs[15]; 213 214 /* Overflow on alternate signal stack gives SIGSEGV. */ 215 if (on_sig_stack(sp) && !on_sig_stack((sp - frame_size) & -8UL)) 216 return (void __user *) -1UL; 217 218 /* This is the X/Open sanctioned signal stack switching. */ 219 if (ka->sa.sa_flags & SA_ONSTACK) { 220 if (! sas_ss_flags(sp)) 221 sp = current->sas_ss_sp + current->sas_ss_size; 222 } 223 224 return (void __user *)((sp - frame_size) & -8ul); 225 } 226 227 static inline int map_signal(int sig) 228 { 229 if (current_thread_info()->exec_domain 230 && current_thread_info()->exec_domain->signal_invmap 231 && sig < 32) 232 return current_thread_info()->exec_domain->signal_invmap[sig]; 233 else 234 return sig; 235 } 236 237 static int setup_frame(int sig, struct k_sigaction *ka, 238 sigset_t *set, struct pt_regs * regs) 239 { 240 sigframe __user *frame; 241 242 frame = get_sigframe(ka, regs, sizeof(sigframe)); 243 if (!access_ok(VERIFY_WRITE, frame, sizeof(sigframe))) 244 goto give_sigsegv; 245 246 if (frame == (void __user *) -1UL) 247 goto give_sigsegv; 248 249 if (__copy_to_user(&frame->sc.oldmask, &set->sig, _SIGMASK_COPY_SIZE)) 250 goto give_sigsegv; 251 252 if (save_sigregs(regs, &frame->sregs)) 253 goto give_sigsegv; 254 if (__put_user(&frame->sregs, &frame->sc.sregs)) 255 goto give_sigsegv; 256 257 /* Set up to return from userspace. If provided, use a stub 258 already in userspace. */ 259 if (ka->sa.sa_flags & SA_RESTORER) { 260 regs->gprs[14] = (unsigned long) 261 ka->sa.sa_restorer | PSW_ADDR_AMODE; 262 } else { 263 regs->gprs[14] = (unsigned long) 264 frame->retcode | PSW_ADDR_AMODE; 265 if (__put_user(S390_SYSCALL_OPCODE | __NR_sigreturn, 266 (u16 __user *)(frame->retcode))) 267 goto give_sigsegv; 268 } 269 270 /* Set up backchain. */ 271 if (__put_user(regs->gprs[15], (addr_t __user *) frame)) 272 goto give_sigsegv; 273 274 /* Set up registers for signal handler */ 275 regs->gprs[15] = (unsigned long) frame; 276 regs->psw.mask |= PSW_MASK_EA | PSW_MASK_BA; /* 64 bit amode */ 277 regs->psw.addr = (unsigned long) ka->sa.sa_handler | PSW_ADDR_AMODE; 278 279 regs->gprs[2] = map_signal(sig); 280 regs->gprs[3] = (unsigned long) &frame->sc; 281 282 /* We forgot to include these in the sigcontext. 283 To avoid breaking binary compatibility, they are passed as args. */ 284 if (sig == SIGSEGV || sig == SIGBUS || sig == SIGILL || 285 sig == SIGTRAP || sig == SIGFPE) { 286 /* set extra registers only for synchronous signals */ 287 regs->gprs[4] = regs->int_code & 127; 288 regs->gprs[5] = regs->int_parm_long; 289 regs->gprs[6] = task_thread_info(current)->last_break; 290 } 291 292 /* Place signal number on stack to allow backtrace from handler. */ 293 if (__put_user(regs->gprs[2], (int __user *) &frame->signo)) 294 goto give_sigsegv; 295 return 0; 296 297 give_sigsegv: 298 force_sigsegv(sig, current); 299 return -EFAULT; 300 } 301 302 static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info, 303 sigset_t *set, struct pt_regs * regs) 304 { 305 int err = 0; 306 rt_sigframe __user *frame; 307 308 frame = get_sigframe(ka, regs, sizeof(rt_sigframe)); 309 if (!access_ok(VERIFY_WRITE, frame, sizeof(rt_sigframe))) 310 goto give_sigsegv; 311 312 if (frame == (void __user *) -1UL) 313 goto give_sigsegv; 314 315 if (copy_siginfo_to_user(&frame->info, info)) 316 goto give_sigsegv; 317 318 /* Create the ucontext. */ 319 err |= __put_user(0, &frame->uc.uc_flags); 320 err |= __put_user(NULL, &frame->uc.uc_link); 321 err |= __put_user((void __user *)current->sas_ss_sp, &frame->uc.uc_stack.ss_sp); 322 err |= __put_user(sas_ss_flags(regs->gprs[15]), 323 &frame->uc.uc_stack.ss_flags); 324 err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size); 325 err |= save_sigregs(regs, &frame->uc.uc_mcontext); 326 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)); 327 if (err) 328 goto give_sigsegv; 329 330 /* Set up to return from userspace. If provided, use a stub 331 already in userspace. */ 332 if (ka->sa.sa_flags & SA_RESTORER) { 333 regs->gprs[14] = (unsigned long) 334 ka->sa.sa_restorer | PSW_ADDR_AMODE; 335 } else { 336 regs->gprs[14] = (unsigned long) 337 frame->retcode | PSW_ADDR_AMODE; 338 if (__put_user(S390_SYSCALL_OPCODE | __NR_rt_sigreturn, 339 (u16 __user *)(frame->retcode))) 340 goto give_sigsegv; 341 } 342 343 /* Set up backchain. */ 344 if (__put_user(regs->gprs[15], (addr_t __user *) frame)) 345 goto give_sigsegv; 346 347 /* Set up registers for signal handler */ 348 regs->gprs[15] = (unsigned long) frame; 349 regs->psw.mask |= PSW_MASK_EA | PSW_MASK_BA; /* 64 bit amode */ 350 regs->psw.addr = (unsigned long) ka->sa.sa_handler | PSW_ADDR_AMODE; 351 352 regs->gprs[2] = map_signal(sig); 353 regs->gprs[3] = (unsigned long) &frame->info; 354 regs->gprs[4] = (unsigned long) &frame->uc; 355 regs->gprs[5] = task_thread_info(current)->last_break; 356 return 0; 357 358 give_sigsegv: 359 force_sigsegv(sig, current); 360 return -EFAULT; 361 } 362 363 static void handle_signal(unsigned long sig, struct k_sigaction *ka, 364 siginfo_t *info, sigset_t *oldset, 365 struct pt_regs *regs) 366 { 367 int ret; 368 369 /* Set up the stack frame */ 370 if (ka->sa.sa_flags & SA_SIGINFO) 371 ret = setup_rt_frame(sig, ka, info, oldset, regs); 372 else 373 ret = setup_frame(sig, ka, oldset, regs); 374 if (ret) 375 return; 376 signal_delivered(sig, info, ka, regs, 377 test_thread_flag(TIF_SINGLE_STEP)); 378 } 379 380 /* 381 * Note that 'init' is a special process: it doesn't get signals it doesn't 382 * want to handle. Thus you cannot kill init even with a SIGKILL even by 383 * mistake. 384 * 385 * Note that we go through the signals twice: once to check the signals that 386 * the kernel can handle, and then we build all the user-level signal handling 387 * stack-frames in one go after that. 388 */ 389 void do_signal(struct pt_regs *regs) 390 { 391 siginfo_t info; 392 int signr; 393 struct k_sigaction ka; 394 sigset_t *oldset = sigmask_to_save(); 395 396 /* 397 * Get signal to deliver. When running under ptrace, at this point 398 * the debugger may change all our registers, including the system 399 * call information. 400 */ 401 current_thread_info()->system_call = 402 test_thread_flag(TIF_SYSCALL) ? regs->int_code : 0; 403 signr = get_signal_to_deliver(&info, &ka, regs, NULL); 404 405 if (signr > 0) { 406 /* Whee! Actually deliver the signal. */ 407 if (current_thread_info()->system_call) { 408 regs->int_code = current_thread_info()->system_call; 409 /* Check for system call restarting. */ 410 switch (regs->gprs[2]) { 411 case -ERESTART_RESTARTBLOCK: 412 case -ERESTARTNOHAND: 413 regs->gprs[2] = -EINTR; 414 break; 415 case -ERESTARTSYS: 416 if (!(ka.sa.sa_flags & SA_RESTART)) { 417 regs->gprs[2] = -EINTR; 418 break; 419 } 420 /* fallthrough */ 421 case -ERESTARTNOINTR: 422 regs->gprs[2] = regs->orig_gpr2; 423 regs->psw.addr = 424 __rewind_psw(regs->psw, 425 regs->int_code >> 16); 426 break; 427 } 428 } 429 /* No longer in a system call */ 430 clear_thread_flag(TIF_SYSCALL); 431 432 if (is_compat_task()) 433 handle_signal32(signr, &ka, &info, oldset, regs); 434 else 435 handle_signal(signr, &ka, &info, oldset, regs); 436 return; 437 } 438 439 /* No handlers present - check for system call restart */ 440 clear_thread_flag(TIF_SYSCALL); 441 if (current_thread_info()->system_call) { 442 regs->int_code = current_thread_info()->system_call; 443 switch (regs->gprs[2]) { 444 case -ERESTART_RESTARTBLOCK: 445 /* Restart with sys_restart_syscall */ 446 regs->int_code = __NR_restart_syscall; 447 /* fallthrough */ 448 case -ERESTARTNOHAND: 449 case -ERESTARTSYS: 450 case -ERESTARTNOINTR: 451 /* Restart system call with magic TIF bit. */ 452 regs->gprs[2] = regs->orig_gpr2; 453 set_thread_flag(TIF_SYSCALL); 454 break; 455 } 456 } 457 458 /* 459 * If there's no signal to deliver, we just put the saved sigmask back. 460 */ 461 restore_saved_sigmask(); 462 } 463 464 void do_notify_resume(struct pt_regs *regs) 465 { 466 clear_thread_flag(TIF_NOTIFY_RESUME); 467 tracehook_notify_resume(regs); 468 } 469