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