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