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 asmlinkage long 43 sys_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, long arg2, 44 long arg3, long arg4, long arg5, long arg6, long arg7, 45 struct pt_regs regs) 46 { 47 return do_sigaltstack(uss, uoss, regs.r12); 48 } 49 50 static long 51 restore_sigcontext (struct sigcontext __user *sc, struct sigscratch *scr) 52 { 53 unsigned long ip, flags, nat, um, cfm, rsc; 54 long err; 55 56 /* Always make any pending restarted system calls return -EINTR */ 57 current_thread_info()->restart_block.fn = do_no_restart_syscall; 58 59 /* restore scratch that always needs gets updated during signal delivery: */ 60 err = __get_user(flags, &sc->sc_flags); 61 err |= __get_user(nat, &sc->sc_nat); 62 err |= __get_user(ip, &sc->sc_ip); /* instruction pointer */ 63 err |= __get_user(cfm, &sc->sc_cfm); 64 err |= __get_user(um, &sc->sc_um); /* user mask */ 65 err |= __get_user(rsc, &sc->sc_ar_rsc); 66 err |= __get_user(scr->pt.ar_unat, &sc->sc_ar_unat); 67 err |= __get_user(scr->pt.ar_fpsr, &sc->sc_ar_fpsr); 68 err |= __get_user(scr->pt.ar_pfs, &sc->sc_ar_pfs); 69 err |= __get_user(scr->pt.pr, &sc->sc_pr); /* predicates */ 70 err |= __get_user(scr->pt.b0, &sc->sc_br[0]); /* b0 (rp) */ 71 err |= __get_user(scr->pt.b6, &sc->sc_br[6]); /* b6 */ 72 err |= __copy_from_user(&scr->pt.r1, &sc->sc_gr[1], 8); /* r1 */ 73 err |= __copy_from_user(&scr->pt.r8, &sc->sc_gr[8], 4*8); /* r8-r11 */ 74 err |= __copy_from_user(&scr->pt.r12, &sc->sc_gr[12], 2*8); /* r12-r13 */ 75 err |= __copy_from_user(&scr->pt.r15, &sc->sc_gr[15], 8); /* r15 */ 76 77 scr->pt.cr_ifs = cfm | (1UL << 63); 78 scr->pt.ar_rsc = rsc | (3 << 2); /* force PL3 */ 79 80 /* establish new instruction pointer: */ 81 scr->pt.cr_iip = ip & ~0x3UL; 82 ia64_psr(&scr->pt)->ri = ip & 0x3; 83 scr->pt.cr_ipsr = (scr->pt.cr_ipsr & ~IA64_PSR_UM) | (um & IA64_PSR_UM); 84 85 scr->scratch_unat = ia64_put_scratch_nat_bits(&scr->pt, nat); 86 87 if (!(flags & IA64_SC_FLAG_IN_SYSCALL)) { 88 /* Restore most scratch-state only when not in syscall. */ 89 err |= __get_user(scr->pt.ar_ccv, &sc->sc_ar_ccv); /* ar.ccv */ 90 err |= __get_user(scr->pt.b7, &sc->sc_br[7]); /* b7 */ 91 err |= __get_user(scr->pt.r14, &sc->sc_gr[14]); /* r14 */ 92 err |= __copy_from_user(&scr->pt.ar_csd, &sc->sc_ar25, 2*8); /* ar.csd & ar.ssd */ 93 err |= __copy_from_user(&scr->pt.r2, &sc->sc_gr[2], 2*8); /* r2-r3 */ 94 err |= __copy_from_user(&scr->pt.r16, &sc->sc_gr[16], 16*8); /* r16-r31 */ 95 } 96 97 if ((flags & IA64_SC_FLAG_FPH_VALID) != 0) { 98 struct ia64_psr *psr = ia64_psr(&scr->pt); 99 100 err |= __copy_from_user(current->thread.fph, &sc->sc_fr[32], 96*16); 101 psr->mfh = 0; /* drop signal handler's fph contents... */ 102 preempt_disable(); 103 if (psr->dfh) 104 ia64_drop_fpu(current); 105 else { 106 /* We already own the local fph, otherwise psr->dfh wouldn't be 0. */ 107 __ia64_load_fpu(current->thread.fph); 108 ia64_set_local_fpu_owner(current); 109 } 110 preempt_enable(); 111 } 112 return err; 113 } 114 115 int 116 copy_siginfo_to_user (siginfo_t __user *to, siginfo_t *from) 117 { 118 if (!access_ok(VERIFY_WRITE, to, sizeof(siginfo_t))) 119 return -EFAULT; 120 if (from->si_code < 0) { 121 if (__copy_to_user(to, from, sizeof(siginfo_t))) 122 return -EFAULT; 123 return 0; 124 } else { 125 int err; 126 127 /* 128 * If you change siginfo_t structure, please be sure this code is fixed 129 * accordingly. It should never copy any pad contained in the structure 130 * to avoid security leaks, but must copy the generic 3 ints plus the 131 * relevant union member. 132 */ 133 err = __put_user(from->si_signo, &to->si_signo); 134 err |= __put_user(from->si_errno, &to->si_errno); 135 err |= __put_user((short)from->si_code, &to->si_code); 136 switch (from->si_code >> 16) { 137 case __SI_FAULT >> 16: 138 err |= __put_user(from->si_flags, &to->si_flags); 139 err |= __put_user(from->si_isr, &to->si_isr); 140 case __SI_POLL >> 16: 141 err |= __put_user(from->si_addr, &to->si_addr); 142 err |= __put_user(from->si_imm, &to->si_imm); 143 break; 144 case __SI_TIMER >> 16: 145 err |= __put_user(from->si_tid, &to->si_tid); 146 err |= __put_user(from->si_overrun, &to->si_overrun); 147 err |= __put_user(from->si_ptr, &to->si_ptr); 148 break; 149 case __SI_RT >> 16: /* Not generated by the kernel as of now. */ 150 case __SI_MESGQ >> 16: 151 err |= __put_user(from->si_uid, &to->si_uid); 152 err |= __put_user(from->si_pid, &to->si_pid); 153 err |= __put_user(from->si_ptr, &to->si_ptr); 154 break; 155 case __SI_CHLD >> 16: 156 err |= __put_user(from->si_utime, &to->si_utime); 157 err |= __put_user(from->si_stime, &to->si_stime); 158 err |= __put_user(from->si_status, &to->si_status); 159 default: 160 err |= __put_user(from->si_uid, &to->si_uid); 161 err |= __put_user(from->si_pid, &to->si_pid); 162 break; 163 } 164 return err; 165 } 166 } 167 168 long 169 ia64_rt_sigreturn (struct sigscratch *scr) 170 { 171 extern char ia64_strace_leave_kernel, ia64_leave_kernel; 172 struct sigcontext __user *sc; 173 struct siginfo si; 174 sigset_t set; 175 long retval; 176 177 sc = &((struct sigframe __user *) (scr->pt.r12 + 16))->sc; 178 179 /* 180 * When we return to the previously executing context, r8 and r10 have already 181 * been setup the way we want them. Indeed, if the signal wasn't delivered while 182 * in a system call, we must not touch r8 or r10 as otherwise user-level state 183 * could be corrupted. 184 */ 185 retval = (long) &ia64_leave_kernel; 186 if (test_thread_flag(TIF_SYSCALL_TRACE) 187 || test_thread_flag(TIF_SYSCALL_AUDIT)) 188 /* 189 * strace expects to be notified after sigreturn returns even though the 190 * context to which we return may not be in the middle of a syscall. 191 * Thus, the return-value that strace displays for sigreturn is 192 * meaningless. 193 */ 194 retval = (long) &ia64_strace_leave_kernel; 195 196 if (!access_ok(VERIFY_READ, sc, sizeof(*sc))) 197 goto give_sigsegv; 198 199 if (GET_SIGSET(&set, &sc->sc_mask)) 200 goto give_sigsegv; 201 202 set_current_blocked(&set); 203 204 if (restore_sigcontext(sc, scr)) 205 goto give_sigsegv; 206 207 #if DEBUG_SIG 208 printk("SIG return (%s:%d): sp=%lx ip=%lx\n", 209 current->comm, current->pid, scr->pt.r12, scr->pt.cr_iip); 210 #endif 211 /* 212 * It is more difficult to avoid calling this function than to 213 * call it and ignore errors. 214 */ 215 do_sigaltstack(&sc->sc_stack, NULL, scr->pt.r12); 216 return retval; 217 218 give_sigsegv: 219 si.si_signo = SIGSEGV; 220 si.si_errno = 0; 221 si.si_code = SI_KERNEL; 222 si.si_pid = task_pid_vnr(current); 223 si.si_uid = from_kuid_munged(current_user_ns(), current_uid()); 224 si.si_addr = sc; 225 force_sig_info(SIGSEGV, &si, current); 226 return retval; 227 } 228 229 /* 230 * This does just the minimum required setup of sigcontext. 231 * Specifically, it only installs data that is either not knowable at 232 * the user-level or that gets modified before execution in the 233 * trampoline starts. Everything else is done at the user-level. 234 */ 235 static long 236 setup_sigcontext (struct sigcontext __user *sc, sigset_t *mask, struct sigscratch *scr) 237 { 238 unsigned long flags = 0, ifs, cfm, nat; 239 long err = 0; 240 241 ifs = scr->pt.cr_ifs; 242 243 if (on_sig_stack((unsigned long) sc)) 244 flags |= IA64_SC_FLAG_ONSTACK; 245 if ((ifs & (1UL << 63)) == 0) 246 /* if cr_ifs doesn't have the valid bit set, we got here through a syscall */ 247 flags |= IA64_SC_FLAG_IN_SYSCALL; 248 cfm = ifs & ((1UL << 38) - 1); 249 ia64_flush_fph(current); 250 if ((current->thread.flags & IA64_THREAD_FPH_VALID)) { 251 flags |= IA64_SC_FLAG_FPH_VALID; 252 err = __copy_to_user(&sc->sc_fr[32], current->thread.fph, 96*16); 253 } 254 255 nat = ia64_get_scratch_nat_bits(&scr->pt, scr->scratch_unat); 256 257 err |= __put_user(flags, &sc->sc_flags); 258 err |= __put_user(nat, &sc->sc_nat); 259 err |= PUT_SIGSET(mask, &sc->sc_mask); 260 err |= __put_user(cfm, &sc->sc_cfm); 261 err |= __put_user(scr->pt.cr_ipsr & IA64_PSR_UM, &sc->sc_um); 262 err |= __put_user(scr->pt.ar_rsc, &sc->sc_ar_rsc); 263 err |= __put_user(scr->pt.ar_unat, &sc->sc_ar_unat); /* ar.unat */ 264 err |= __put_user(scr->pt.ar_fpsr, &sc->sc_ar_fpsr); /* ar.fpsr */ 265 err |= __put_user(scr->pt.ar_pfs, &sc->sc_ar_pfs); 266 err |= __put_user(scr->pt.pr, &sc->sc_pr); /* predicates */ 267 err |= __put_user(scr->pt.b0, &sc->sc_br[0]); /* b0 (rp) */ 268 err |= __put_user(scr->pt.b6, &sc->sc_br[6]); /* b6 */ 269 err |= __copy_to_user(&sc->sc_gr[1], &scr->pt.r1, 8); /* r1 */ 270 err |= __copy_to_user(&sc->sc_gr[8], &scr->pt.r8, 4*8); /* r8-r11 */ 271 err |= __copy_to_user(&sc->sc_gr[12], &scr->pt.r12, 2*8); /* r12-r13 */ 272 err |= __copy_to_user(&sc->sc_gr[15], &scr->pt.r15, 8); /* r15 */ 273 err |= __put_user(scr->pt.cr_iip + ia64_psr(&scr->pt)->ri, &sc->sc_ip); 274 275 if (!(flags & IA64_SC_FLAG_IN_SYSCALL)) { 276 /* Copy scratch regs to sigcontext if the signal didn't interrupt a syscall. */ 277 err |= __put_user(scr->pt.ar_ccv, &sc->sc_ar_ccv); /* ar.ccv */ 278 err |= __put_user(scr->pt.b7, &sc->sc_br[7]); /* b7 */ 279 err |= __put_user(scr->pt.r14, &sc->sc_gr[14]); /* r14 */ 280 err |= __copy_to_user(&sc->sc_ar25, &scr->pt.ar_csd, 2*8); /* ar.csd & ar.ssd */ 281 err |= __copy_to_user(&sc->sc_gr[2], &scr->pt.r2, 2*8); /* r2-r3 */ 282 err |= __copy_to_user(&sc->sc_gr[16], &scr->pt.r16, 16*8); /* r16-r31 */ 283 } 284 return err; 285 } 286 287 /* 288 * Check whether the register-backing store is already on the signal stack. 289 */ 290 static inline int 291 rbs_on_sig_stack (unsigned long bsp) 292 { 293 return (bsp - current->sas_ss_sp < current->sas_ss_size); 294 } 295 296 static long 297 force_sigsegv_info (int sig, void __user *addr) 298 { 299 unsigned long flags; 300 struct siginfo si; 301 302 if (sig == SIGSEGV) { 303 /* 304 * Acquiring siglock around the sa_handler-update is almost 305 * certainly overkill, but this isn't a 306 * performance-critical path and I'd rather play it safe 307 * here than having to debug a nasty race if and when 308 * something changes in kernel/signal.c that would make it 309 * no longer safe to modify sa_handler without holding the 310 * lock. 311 */ 312 spin_lock_irqsave(¤t->sighand->siglock, flags); 313 current->sighand->action[sig - 1].sa.sa_handler = SIG_DFL; 314 spin_unlock_irqrestore(¤t->sighand->siglock, flags); 315 } 316 si.si_signo = SIGSEGV; 317 si.si_errno = 0; 318 si.si_code = SI_KERNEL; 319 si.si_pid = task_pid_vnr(current); 320 si.si_uid = from_kuid_munged(current_user_ns(), current_uid()); 321 si.si_addr = addr; 322 force_sig_info(SIGSEGV, &si, current); 323 return 0; 324 } 325 326 static long 327 setup_frame (int sig, struct k_sigaction *ka, siginfo_t *info, sigset_t *set, 328 struct sigscratch *scr) 329 { 330 extern char __kernel_sigtramp[]; 331 unsigned long tramp_addr, new_rbs = 0, new_sp; 332 struct sigframe __user *frame; 333 long err; 334 335 new_sp = scr->pt.r12; 336 tramp_addr = (unsigned long) __kernel_sigtramp; 337 if (ka->sa.sa_flags & SA_ONSTACK) { 338 int onstack = sas_ss_flags(new_sp); 339 340 if (onstack == 0) { 341 new_sp = current->sas_ss_sp + current->sas_ss_size; 342 /* 343 * We need to check for the register stack being on the 344 * signal stack separately, because it's switched 345 * separately (memory stack is switched in the kernel, 346 * register stack is switched in the signal trampoline). 347 */ 348 if (!rbs_on_sig_stack(scr->pt.ar_bspstore)) 349 new_rbs = ALIGN(current->sas_ss_sp, 350 sizeof(long)); 351 } else if (onstack == SS_ONSTACK) { 352 unsigned long check_sp; 353 354 /* 355 * If we are on the alternate signal stack and would 356 * overflow it, don't. Return an always-bogus address 357 * instead so we will die with SIGSEGV. 358 */ 359 check_sp = (new_sp - sizeof(*frame)) & -STACK_ALIGN; 360 if (!likely(on_sig_stack(check_sp))) 361 return force_sigsegv_info(sig, (void __user *) 362 check_sp); 363 } 364 } 365 frame = (void __user *) ((new_sp - sizeof(*frame)) & -STACK_ALIGN); 366 367 if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame))) 368 return force_sigsegv_info(sig, frame); 369 370 err = __put_user(sig, &frame->arg0); 371 err |= __put_user(&frame->info, &frame->arg1); 372 err |= __put_user(&frame->sc, &frame->arg2); 373 err |= __put_user(new_rbs, &frame->sc.sc_rbs_base); 374 err |= __put_user(0, &frame->sc.sc_loadrs); /* initialize to zero */ 375 err |= __put_user(ka->sa.sa_handler, &frame->handler); 376 377 err |= copy_siginfo_to_user(&frame->info, info); 378 379 err |= __put_user(current->sas_ss_sp, &frame->sc.sc_stack.ss_sp); 380 err |= __put_user(current->sas_ss_size, &frame->sc.sc_stack.ss_size); 381 err |= __put_user(sas_ss_flags(scr->pt.r12), &frame->sc.sc_stack.ss_flags); 382 err |= setup_sigcontext(&frame->sc, set, scr); 383 384 if (unlikely(err)) 385 return force_sigsegv_info(sig, frame); 386 387 scr->pt.r12 = (unsigned long) frame - 16; /* new stack pointer */ 388 scr->pt.ar_fpsr = FPSR_DEFAULT; /* reset fpsr for signal handler */ 389 scr->pt.cr_iip = tramp_addr; 390 ia64_psr(&scr->pt)->ri = 0; /* start executing in first slot */ 391 ia64_psr(&scr->pt)->be = 0; /* force little-endian byte-order */ 392 /* 393 * Force the interruption function mask to zero. This has no effect when a 394 * system-call got interrupted by a signal (since, in that case, scr->pt_cr_ifs is 395 * ignored), but it has the desirable effect of making it possible to deliver a 396 * signal with an incomplete register frame (which happens when a mandatory RSE 397 * load faults). Furthermore, it has no negative effect on the getting the user's 398 * dirty partition preserved, because that's governed by scr->pt.loadrs. 399 */ 400 scr->pt.cr_ifs = (1UL << 63); 401 402 /* 403 * Note: this affects only the NaT bits of the scratch regs (the ones saved in 404 * pt_regs), which is exactly what we want. 405 */ 406 scr->scratch_unat = 0; /* ensure NaT bits of r12 is clear */ 407 408 #if DEBUG_SIG 409 printk("SIG deliver (%s:%d): sig=%d sp=%lx ip=%lx handler=%p\n", 410 current->comm, current->pid, sig, scr->pt.r12, frame->sc.sc_ip, frame->handler); 411 #endif 412 return 1; 413 } 414 415 static long 416 handle_signal (unsigned long sig, struct k_sigaction *ka, siginfo_t *info, 417 struct sigscratch *scr) 418 { 419 if (!setup_frame(sig, ka, info, sigmask_to_save(), scr)) 420 return 0; 421 422 signal_delivered(sig, info, ka, &scr->pt, 423 test_thread_flag(TIF_SINGLESTEP)); 424 425 return 1; 426 } 427 428 /* 429 * Note that `init' is a special process: it doesn't get signals it doesn't want to 430 * handle. Thus you cannot kill init even with a SIGKILL even by mistake. 431 */ 432 void 433 ia64_do_signal (struct sigscratch *scr, long in_syscall) 434 { 435 struct k_sigaction ka; 436 siginfo_t info; 437 long restart = in_syscall; 438 long errno = scr->pt.r8; 439 440 /* 441 * This only loops in the rare cases of handle_signal() failing, in which case we 442 * need to push through a forced SIGSEGV. 443 */ 444 while (1) { 445 int signr = get_signal_to_deliver(&info, &ka, &scr->pt, NULL); 446 447 /* 448 * get_signal_to_deliver() may have run a debugger (via notify_parent()) 449 * and the debugger may have modified the state (e.g., to arrange for an 450 * inferior call), thus it's important to check for restarting _after_ 451 * get_signal_to_deliver(). 452 */ 453 if ((long) scr->pt.r10 != -1) 454 /* 455 * A system calls has to be restarted only if one of the error codes 456 * ERESTARTNOHAND, ERESTARTSYS, or ERESTARTNOINTR is returned. If r10 457 * isn't -1 then r8 doesn't hold an error code and we don't need to 458 * restart the syscall, so we can clear the "restart" flag here. 459 */ 460 restart = 0; 461 462 if (signr <= 0) 463 break; 464 465 if (unlikely(restart)) { 466 switch (errno) { 467 case ERESTART_RESTARTBLOCK: 468 case ERESTARTNOHAND: 469 scr->pt.r8 = EINTR; 470 /* note: scr->pt.r10 is already -1 */ 471 break; 472 473 case ERESTARTSYS: 474 if ((ka.sa.sa_flags & SA_RESTART) == 0) { 475 scr->pt.r8 = EINTR; 476 /* note: scr->pt.r10 is already -1 */ 477 break; 478 } 479 case ERESTARTNOINTR: 480 ia64_decrement_ip(&scr->pt); 481 restart = 0; /* don't restart twice if handle_signal() fails... */ 482 } 483 } 484 485 /* 486 * Whee! Actually deliver the signal. If the delivery failed, we need to 487 * continue to iterate in this loop so we can deliver the SIGSEGV... 488 */ 489 if (handle_signal(signr, &ka, &info, scr)) 490 return; 491 } 492 493 /* Did we come from a system call? */ 494 if (restart) { 495 /* Restart the system call - no handlers present */ 496 if (errno == ERESTARTNOHAND || errno == ERESTARTSYS || errno == ERESTARTNOINTR 497 || errno == ERESTART_RESTARTBLOCK) 498 { 499 /* 500 * Note: the syscall number is in r15 which is saved in 501 * pt_regs so all we need to do here is adjust ip so that 502 * the "break" instruction gets re-executed. 503 */ 504 ia64_decrement_ip(&scr->pt); 505 if (errno == ERESTART_RESTARTBLOCK) 506 scr->pt.r15 = __NR_restart_syscall; 507 } 508 } 509 510 /* if there's no signal to deliver, we just put the saved sigmask 511 * back */ 512 restore_saved_sigmask(); 513 } 514