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