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