1 /* 2 * Architecture-specific signal handling support. 3 * 4 * Copyright (C) 1999-2004 Hewlett-Packard Co 5 * David Mosberger-Tang <davidm@hpl.hp.com> 6 * 7 * Derived from i386 and Alpha versions. 8 */ 9 10 #include <linux/errno.h> 11 #include <linux/kernel.h> 12 #include <linux/mm.h> 13 #include <linux/ptrace.h> 14 #include <linux/tracehook.h> 15 #include <linux/sched.h> 16 #include <linux/signal.h> 17 #include <linux/smp.h> 18 #include <linux/stddef.h> 19 #include <linux/tty.h> 20 #include <linux/binfmts.h> 21 #include <linux/unistd.h> 22 #include <linux/wait.h> 23 24 #include <asm/intrinsics.h> 25 #include <asm/uaccess.h> 26 #include <asm/rse.h> 27 #include <asm/sigcontext.h> 28 29 #include "sigframe.h" 30 31 #define DEBUG_SIG 0 32 #define STACK_ALIGN 16 /* minimal alignment for stack pointer */ 33 34 #if _NSIG_WORDS > 1 35 # define PUT_SIGSET(k,u) __copy_to_user((u)->sig, (k)->sig, sizeof(sigset_t)) 36 # define GET_SIGSET(k,u) __copy_from_user((k)->sig, (u)->sig, sizeof(sigset_t)) 37 #else 38 # define PUT_SIGSET(k,u) __put_user((k)->sig[0], &(u)->sig[0]) 39 # define GET_SIGSET(k,u) __get_user((k)->sig[0], &(u)->sig[0]) 40 #endif 41 42 static long 43 restore_sigcontext (struct sigcontext __user *sc, struct sigscratch *scr) 44 { 45 unsigned long ip, flags, nat, um, cfm, rsc; 46 long err; 47 48 /* Always make any pending restarted system calls return -EINTR */ 49 current_thread_info()->restart_block.fn = do_no_restart_syscall; 50 51 /* restore scratch that always needs gets updated during signal delivery: */ 52 err = __get_user(flags, &sc->sc_flags); 53 err |= __get_user(nat, &sc->sc_nat); 54 err |= __get_user(ip, &sc->sc_ip); /* instruction pointer */ 55 err |= __get_user(cfm, &sc->sc_cfm); 56 err |= __get_user(um, &sc->sc_um); /* user mask */ 57 err |= __get_user(rsc, &sc->sc_ar_rsc); 58 err |= __get_user(scr->pt.ar_unat, &sc->sc_ar_unat); 59 err |= __get_user(scr->pt.ar_fpsr, &sc->sc_ar_fpsr); 60 err |= __get_user(scr->pt.ar_pfs, &sc->sc_ar_pfs); 61 err |= __get_user(scr->pt.pr, &sc->sc_pr); /* predicates */ 62 err |= __get_user(scr->pt.b0, &sc->sc_br[0]); /* b0 (rp) */ 63 err |= __get_user(scr->pt.b6, &sc->sc_br[6]); /* b6 */ 64 err |= __copy_from_user(&scr->pt.r1, &sc->sc_gr[1], 8); /* r1 */ 65 err |= __copy_from_user(&scr->pt.r8, &sc->sc_gr[8], 4*8); /* r8-r11 */ 66 err |= __copy_from_user(&scr->pt.r12, &sc->sc_gr[12], 2*8); /* r12-r13 */ 67 err |= __copy_from_user(&scr->pt.r15, &sc->sc_gr[15], 8); /* r15 */ 68 69 scr->pt.cr_ifs = cfm | (1UL << 63); 70 scr->pt.ar_rsc = rsc | (3 << 2); /* force PL3 */ 71 72 /* establish new instruction pointer: */ 73 scr->pt.cr_iip = ip & ~0x3UL; 74 ia64_psr(&scr->pt)->ri = ip & 0x3; 75 scr->pt.cr_ipsr = (scr->pt.cr_ipsr & ~IA64_PSR_UM) | (um & IA64_PSR_UM); 76 77 scr->scratch_unat = ia64_put_scratch_nat_bits(&scr->pt, nat); 78 79 if (!(flags & IA64_SC_FLAG_IN_SYSCALL)) { 80 /* Restore most scratch-state only when not in syscall. */ 81 err |= __get_user(scr->pt.ar_ccv, &sc->sc_ar_ccv); /* ar.ccv */ 82 err |= __get_user(scr->pt.b7, &sc->sc_br[7]); /* b7 */ 83 err |= __get_user(scr->pt.r14, &sc->sc_gr[14]); /* r14 */ 84 err |= __copy_from_user(&scr->pt.ar_csd, &sc->sc_ar25, 2*8); /* ar.csd & ar.ssd */ 85 err |= __copy_from_user(&scr->pt.r2, &sc->sc_gr[2], 2*8); /* r2-r3 */ 86 err |= __copy_from_user(&scr->pt.r16, &sc->sc_gr[16], 16*8); /* r16-r31 */ 87 } 88 89 if ((flags & IA64_SC_FLAG_FPH_VALID) != 0) { 90 struct ia64_psr *psr = ia64_psr(&scr->pt); 91 92 err |= __copy_from_user(current->thread.fph, &sc->sc_fr[32], 96*16); 93 psr->mfh = 0; /* drop signal handler's fph contents... */ 94 preempt_disable(); 95 if (psr->dfh) 96 ia64_drop_fpu(current); 97 else { 98 /* We already own the local fph, otherwise psr->dfh wouldn't be 0. */ 99 __ia64_load_fpu(current->thread.fph); 100 ia64_set_local_fpu_owner(current); 101 } 102 preempt_enable(); 103 } 104 return err; 105 } 106 107 int 108 copy_siginfo_to_user (siginfo_t __user *to, const siginfo_t *from) 109 { 110 if (!access_ok(VERIFY_WRITE, to, sizeof(siginfo_t))) 111 return -EFAULT; 112 if (from->si_code < 0) { 113 if (__copy_to_user(to, from, sizeof(siginfo_t))) 114 return -EFAULT; 115 return 0; 116 } else { 117 int err; 118 119 /* 120 * If you change siginfo_t structure, please be sure this code is fixed 121 * accordingly. It should never copy any pad contained in the structure 122 * to avoid security leaks, but must copy the generic 3 ints plus the 123 * relevant union member. 124 */ 125 err = __put_user(from->si_signo, &to->si_signo); 126 err |= __put_user(from->si_errno, &to->si_errno); 127 err |= __put_user((short)from->si_code, &to->si_code); 128 switch (from->si_code >> 16) { 129 case __SI_FAULT >> 16: 130 err |= __put_user(from->si_flags, &to->si_flags); 131 err |= __put_user(from->si_isr, &to->si_isr); 132 case __SI_POLL >> 16: 133 err |= __put_user(from->si_addr, &to->si_addr); 134 err |= __put_user(from->si_imm, &to->si_imm); 135 break; 136 case __SI_TIMER >> 16: 137 err |= __put_user(from->si_tid, &to->si_tid); 138 err |= __put_user(from->si_overrun, &to->si_overrun); 139 err |= __put_user(from->si_ptr, &to->si_ptr); 140 break; 141 case __SI_RT >> 16: /* Not generated by the kernel as of now. */ 142 case __SI_MESGQ >> 16: 143 err |= __put_user(from->si_uid, &to->si_uid); 144 err |= __put_user(from->si_pid, &to->si_pid); 145 err |= __put_user(from->si_ptr, &to->si_ptr); 146 break; 147 case __SI_CHLD >> 16: 148 err |= __put_user(from->si_utime, &to->si_utime); 149 err |= __put_user(from->si_stime, &to->si_stime); 150 err |= __put_user(from->si_status, &to->si_status); 151 default: 152 err |= __put_user(from->si_uid, &to->si_uid); 153 err |= __put_user(from->si_pid, &to->si_pid); 154 break; 155 } 156 return err; 157 } 158 } 159 160 long 161 ia64_rt_sigreturn (struct sigscratch *scr) 162 { 163 extern char ia64_strace_leave_kernel, ia64_leave_kernel; 164 struct sigcontext __user *sc; 165 struct siginfo si; 166 sigset_t set; 167 long retval; 168 169 sc = &((struct sigframe __user *) (scr->pt.r12 + 16))->sc; 170 171 /* 172 * When we return to the previously executing context, r8 and r10 have already 173 * been setup the way we want them. Indeed, if the signal wasn't delivered while 174 * in a system call, we must not touch r8 or r10 as otherwise user-level state 175 * could be corrupted. 176 */ 177 retval = (long) &ia64_leave_kernel; 178 if (test_thread_flag(TIF_SYSCALL_TRACE) 179 || test_thread_flag(TIF_SYSCALL_AUDIT)) 180 /* 181 * strace expects to be notified after sigreturn returns even though the 182 * context to which we return may not be in the middle of a syscall. 183 * Thus, the return-value that strace displays for sigreturn is 184 * meaningless. 185 */ 186 retval = (long) &ia64_strace_leave_kernel; 187 188 if (!access_ok(VERIFY_READ, sc, sizeof(*sc))) 189 goto give_sigsegv; 190 191 if (GET_SIGSET(&set, &sc->sc_mask)) 192 goto give_sigsegv; 193 194 set_current_blocked(&set); 195 196 if (restore_sigcontext(sc, scr)) 197 goto give_sigsegv; 198 199 #if DEBUG_SIG 200 printk("SIG return (%s:%d): sp=%lx ip=%lx\n", 201 current->comm, current->pid, scr->pt.r12, scr->pt.cr_iip); 202 #endif 203 if (restore_altstack(&sc->sc_stack)) 204 goto give_sigsegv; 205 return retval; 206 207 give_sigsegv: 208 si.si_signo = SIGSEGV; 209 si.si_errno = 0; 210 si.si_code = SI_KERNEL; 211 si.si_pid = task_pid_vnr(current); 212 si.si_uid = from_kuid_munged(current_user_ns(), current_uid()); 213 si.si_addr = sc; 214 force_sig_info(SIGSEGV, &si, current); 215 return retval; 216 } 217 218 /* 219 * This does just the minimum required setup of sigcontext. 220 * Specifically, it only installs data that is either not knowable at 221 * the user-level or that gets modified before execution in the 222 * trampoline starts. Everything else is done at the user-level. 223 */ 224 static long 225 setup_sigcontext (struct sigcontext __user *sc, sigset_t *mask, struct sigscratch *scr) 226 { 227 unsigned long flags = 0, ifs, cfm, nat; 228 long err = 0; 229 230 ifs = scr->pt.cr_ifs; 231 232 if (on_sig_stack((unsigned long) sc)) 233 flags |= IA64_SC_FLAG_ONSTACK; 234 if ((ifs & (1UL << 63)) == 0) 235 /* if cr_ifs doesn't have the valid bit set, we got here through a syscall */ 236 flags |= IA64_SC_FLAG_IN_SYSCALL; 237 cfm = ifs & ((1UL << 38) - 1); 238 ia64_flush_fph(current); 239 if ((current->thread.flags & IA64_THREAD_FPH_VALID)) { 240 flags |= IA64_SC_FLAG_FPH_VALID; 241 err = __copy_to_user(&sc->sc_fr[32], current->thread.fph, 96*16); 242 } 243 244 nat = ia64_get_scratch_nat_bits(&scr->pt, scr->scratch_unat); 245 246 err |= __put_user(flags, &sc->sc_flags); 247 err |= __put_user(nat, &sc->sc_nat); 248 err |= PUT_SIGSET(mask, &sc->sc_mask); 249 err |= __put_user(cfm, &sc->sc_cfm); 250 err |= __put_user(scr->pt.cr_ipsr & IA64_PSR_UM, &sc->sc_um); 251 err |= __put_user(scr->pt.ar_rsc, &sc->sc_ar_rsc); 252 err |= __put_user(scr->pt.ar_unat, &sc->sc_ar_unat); /* ar.unat */ 253 err |= __put_user(scr->pt.ar_fpsr, &sc->sc_ar_fpsr); /* ar.fpsr */ 254 err |= __put_user(scr->pt.ar_pfs, &sc->sc_ar_pfs); 255 err |= __put_user(scr->pt.pr, &sc->sc_pr); /* predicates */ 256 err |= __put_user(scr->pt.b0, &sc->sc_br[0]); /* b0 (rp) */ 257 err |= __put_user(scr->pt.b6, &sc->sc_br[6]); /* b6 */ 258 err |= __copy_to_user(&sc->sc_gr[1], &scr->pt.r1, 8); /* r1 */ 259 err |= __copy_to_user(&sc->sc_gr[8], &scr->pt.r8, 4*8); /* r8-r11 */ 260 err |= __copy_to_user(&sc->sc_gr[12], &scr->pt.r12, 2*8); /* r12-r13 */ 261 err |= __copy_to_user(&sc->sc_gr[15], &scr->pt.r15, 8); /* r15 */ 262 err |= __put_user(scr->pt.cr_iip + ia64_psr(&scr->pt)->ri, &sc->sc_ip); 263 264 if (!(flags & IA64_SC_FLAG_IN_SYSCALL)) { 265 /* Copy scratch regs to sigcontext if the signal didn't interrupt a syscall. */ 266 err |= __put_user(scr->pt.ar_ccv, &sc->sc_ar_ccv); /* ar.ccv */ 267 err |= __put_user(scr->pt.b7, &sc->sc_br[7]); /* b7 */ 268 err |= __put_user(scr->pt.r14, &sc->sc_gr[14]); /* r14 */ 269 err |= __copy_to_user(&sc->sc_ar25, &scr->pt.ar_csd, 2*8); /* ar.csd & ar.ssd */ 270 err |= __copy_to_user(&sc->sc_gr[2], &scr->pt.r2, 2*8); /* r2-r3 */ 271 err |= __copy_to_user(&sc->sc_gr[16], &scr->pt.r16, 16*8); /* r16-r31 */ 272 } 273 return err; 274 } 275 276 /* 277 * Check whether the register-backing store is already on the signal stack. 278 */ 279 static inline int 280 rbs_on_sig_stack (unsigned long bsp) 281 { 282 return (bsp - current->sas_ss_sp < current->sas_ss_size); 283 } 284 285 static long 286 force_sigsegv_info (int sig, void __user *addr) 287 { 288 unsigned long flags; 289 struct siginfo si; 290 291 if (sig == SIGSEGV) { 292 /* 293 * Acquiring siglock around the sa_handler-update is almost 294 * certainly overkill, but this isn't a 295 * performance-critical path and I'd rather play it safe 296 * here than having to debug a nasty race if and when 297 * something changes in kernel/signal.c that would make it 298 * no longer safe to modify sa_handler without holding the 299 * lock. 300 */ 301 spin_lock_irqsave(¤t->sighand->siglock, flags); 302 current->sighand->action[sig - 1].sa.sa_handler = SIG_DFL; 303 spin_unlock_irqrestore(¤t->sighand->siglock, flags); 304 } 305 si.si_signo = SIGSEGV; 306 si.si_errno = 0; 307 si.si_code = SI_KERNEL; 308 si.si_pid = task_pid_vnr(current); 309 si.si_uid = from_kuid_munged(current_user_ns(), current_uid()); 310 si.si_addr = addr; 311 force_sig_info(SIGSEGV, &si, current); 312 return 0; 313 } 314 315 static long 316 setup_frame (int sig, struct k_sigaction *ka, siginfo_t *info, sigset_t *set, 317 struct sigscratch *scr) 318 { 319 extern char __kernel_sigtramp[]; 320 unsigned long tramp_addr, new_rbs = 0, new_sp; 321 struct sigframe __user *frame; 322 long err; 323 324 new_sp = scr->pt.r12; 325 tramp_addr = (unsigned long) __kernel_sigtramp; 326 if (ka->sa.sa_flags & SA_ONSTACK) { 327 int onstack = sas_ss_flags(new_sp); 328 329 if (onstack == 0) { 330 new_sp = current->sas_ss_sp + current->sas_ss_size; 331 /* 332 * We need to check for the register stack being on the 333 * signal stack separately, because it's switched 334 * separately (memory stack is switched in the kernel, 335 * register stack is switched in the signal trampoline). 336 */ 337 if (!rbs_on_sig_stack(scr->pt.ar_bspstore)) 338 new_rbs = ALIGN(current->sas_ss_sp, 339 sizeof(long)); 340 } else if (onstack == SS_ONSTACK) { 341 unsigned long check_sp; 342 343 /* 344 * If we are on the alternate signal stack and would 345 * overflow it, don't. Return an always-bogus address 346 * instead so we will die with SIGSEGV. 347 */ 348 check_sp = (new_sp - sizeof(*frame)) & -STACK_ALIGN; 349 if (!likely(on_sig_stack(check_sp))) 350 return force_sigsegv_info(sig, (void __user *) 351 check_sp); 352 } 353 } 354 frame = (void __user *) ((new_sp - sizeof(*frame)) & -STACK_ALIGN); 355 356 if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame))) 357 return force_sigsegv_info(sig, frame); 358 359 err = __put_user(sig, &frame->arg0); 360 err |= __put_user(&frame->info, &frame->arg1); 361 err |= __put_user(&frame->sc, &frame->arg2); 362 err |= __put_user(new_rbs, &frame->sc.sc_rbs_base); 363 err |= __put_user(0, &frame->sc.sc_loadrs); /* initialize to zero */ 364 err |= __put_user(ka->sa.sa_handler, &frame->handler); 365 366 err |= copy_siginfo_to_user(&frame->info, info); 367 368 err |= __save_altstack(&frame->sc.sc_stack, scr->pt.r12); 369 err |= setup_sigcontext(&frame->sc, set, scr); 370 371 if (unlikely(err)) 372 return force_sigsegv_info(sig, frame); 373 374 scr->pt.r12 = (unsigned long) frame - 16; /* new stack pointer */ 375 scr->pt.ar_fpsr = FPSR_DEFAULT; /* reset fpsr for signal handler */ 376 scr->pt.cr_iip = tramp_addr; 377 ia64_psr(&scr->pt)->ri = 0; /* start executing in first slot */ 378 ia64_psr(&scr->pt)->be = 0; /* force little-endian byte-order */ 379 /* 380 * Force the interruption function mask to zero. This has no effect when a 381 * system-call got interrupted by a signal (since, in that case, scr->pt_cr_ifs is 382 * ignored), but it has the desirable effect of making it possible to deliver a 383 * signal with an incomplete register frame (which happens when a mandatory RSE 384 * load faults). Furthermore, it has no negative effect on the getting the user's 385 * dirty partition preserved, because that's governed by scr->pt.loadrs. 386 */ 387 scr->pt.cr_ifs = (1UL << 63); 388 389 /* 390 * Note: this affects only the NaT bits of the scratch regs (the ones saved in 391 * pt_regs), which is exactly what we want. 392 */ 393 scr->scratch_unat = 0; /* ensure NaT bits of r12 is clear */ 394 395 #if DEBUG_SIG 396 printk("SIG deliver (%s:%d): sig=%d sp=%lx ip=%lx handler=%p\n", 397 current->comm, current->pid, sig, scr->pt.r12, frame->sc.sc_ip, frame->handler); 398 #endif 399 return 1; 400 } 401 402 static long 403 handle_signal (unsigned long sig, struct k_sigaction *ka, siginfo_t *info, 404 struct sigscratch *scr) 405 { 406 if (!setup_frame(sig, ka, info, sigmask_to_save(), scr)) 407 return 0; 408 409 signal_delivered(sig, info, ka, &scr->pt, 410 test_thread_flag(TIF_SINGLESTEP)); 411 412 return 1; 413 } 414 415 /* 416 * Note that `init' is a special process: it doesn't get signals it doesn't want to 417 * handle. Thus you cannot kill init even with a SIGKILL even by mistake. 418 */ 419 void 420 ia64_do_signal (struct sigscratch *scr, long in_syscall) 421 { 422 struct k_sigaction ka; 423 siginfo_t info; 424 long restart = in_syscall; 425 long errno = scr->pt.r8; 426 427 /* 428 * This only loops in the rare cases of handle_signal() failing, in which case we 429 * need to push through a forced SIGSEGV. 430 */ 431 while (1) { 432 int signr = get_signal_to_deliver(&info, &ka, &scr->pt, NULL); 433 434 /* 435 * get_signal_to_deliver() may have run a debugger (via notify_parent()) 436 * and the debugger may have modified the state (e.g., to arrange for an 437 * inferior call), thus it's important to check for restarting _after_ 438 * get_signal_to_deliver(). 439 */ 440 if ((long) scr->pt.r10 != -1) 441 /* 442 * A system calls has to be restarted only if one of the error codes 443 * ERESTARTNOHAND, ERESTARTSYS, or ERESTARTNOINTR is returned. If r10 444 * isn't -1 then r8 doesn't hold an error code and we don't need to 445 * restart the syscall, so we can clear the "restart" flag here. 446 */ 447 restart = 0; 448 449 if (signr <= 0) 450 break; 451 452 if (unlikely(restart)) { 453 switch (errno) { 454 case ERESTART_RESTARTBLOCK: 455 case ERESTARTNOHAND: 456 scr->pt.r8 = EINTR; 457 /* note: scr->pt.r10 is already -1 */ 458 break; 459 460 case ERESTARTSYS: 461 if ((ka.sa.sa_flags & SA_RESTART) == 0) { 462 scr->pt.r8 = EINTR; 463 /* note: scr->pt.r10 is already -1 */ 464 break; 465 } 466 case ERESTARTNOINTR: 467 ia64_decrement_ip(&scr->pt); 468 restart = 0; /* don't restart twice if handle_signal() fails... */ 469 } 470 } 471 472 /* 473 * Whee! Actually deliver the signal. If the delivery failed, we need to 474 * continue to iterate in this loop so we can deliver the SIGSEGV... 475 */ 476 if (handle_signal(signr, &ka, &info, scr)) 477 return; 478 } 479 480 /* Did we come from a system call? */ 481 if (restart) { 482 /* Restart the system call - no handlers present */ 483 if (errno == ERESTARTNOHAND || errno == ERESTARTSYS || errno == ERESTARTNOINTR 484 || errno == ERESTART_RESTARTBLOCK) 485 { 486 /* 487 * Note: the syscall number is in r15 which is saved in 488 * pt_regs so all we need to do here is adjust ip so that 489 * the "break" instruction gets re-executed. 490 */ 491 ia64_decrement_ip(&scr->pt); 492 if (errno == ERESTART_RESTARTBLOCK) 493 scr->pt.r15 = __NR_restart_syscall; 494 } 495 } 496 497 /* if there's no signal to deliver, we just put the saved sigmask 498 * back */ 499 restore_saved_sigmask(); 500 } 501