1/* 2 * Copyright (C) 2003, Axis Communications AB. 3 */ 4 5#include <linux/sched.h> 6#include <linux/mm.h> 7#include <linux/slab.h> 8#include <linux/kernel.h> 9#include <linux/signal.h> 10#include <linux/errno.h> 11#include <linux/wait.h> 12#include <linux/ptrace.h> 13#include <linux/unistd.h> 14#include <linux/stddef.h> 15#include <linux/syscalls.h> 16#include <linux/vmalloc.h> 17 18#include <asm/io.h> 19#include <asm/processor.h> 20#include <asm/ucontext.h> 21#include <asm/uaccess.h> 22#include <arch/ptrace.h> 23#include <arch/hwregs/cpu_vect.h> 24 25extern unsigned long cris_signal_return_page; 26 27/* Flag to check if a signal is blockable. */ 28#define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP))) 29 30/* 31 * A syscall in CRIS is really a "break 13" instruction, which is 2 32 * bytes. The registers is manipulated so upon return the instruction 33 * will be executed again. 34 * 35 * This relies on that PC points to the instruction after the break call. 36 */ 37#define RESTART_CRIS_SYS(regs) regs->r10 = regs->orig_r10; regs->erp -= 2; 38 39/* Signal frames. */ 40struct signal_frame { 41 struct sigcontext sc; 42 unsigned long extramask[_NSIG_WORDS - 1]; 43 unsigned char retcode[8]; /* Trampoline code. */ 44}; 45 46struct rt_signal_frame { 47 struct siginfo *pinfo; 48 void *puc; 49 struct siginfo info; 50 struct ucontext uc; 51 unsigned char retcode[8]; /* Trampoline code. */ 52}; 53 54void do_signal(int restart, struct pt_regs *regs); 55void keep_debug_flags(unsigned long oldccs, unsigned long oldspc, 56 struct pt_regs *regs); 57/* 58 * Swap in the new signal mask, and wait for a signal. Define some 59 * dummy arguments to be able to reach the regs argument. 60 */ 61int 62sys_sigsuspend(old_sigset_t mask, long r11, long r12, long r13, long mof, 63 long srp, struct pt_regs *regs) 64{ 65 mask &= _BLOCKABLE; 66 spin_lock_irq(¤t->sighand->siglock); 67 current->saved_sigmask = current->blocked; 68 siginitset(¤t->blocked, mask); 69 recalc_sigpending(); 70 spin_unlock_irq(¤t->sighand->siglock); 71 current->state = TASK_INTERRUPTIBLE; 72 schedule(); 73 set_thread_flag(TIF_RESTORE_SIGMASK); 74 return -ERESTARTNOHAND; 75} 76 77int 78sys_sigaction(int signal, const struct old_sigaction *act, 79 struct old_sigaction *oact) 80{ 81 int retval; 82 struct k_sigaction newk; 83 struct k_sigaction oldk; 84 85 if (act) { 86 old_sigset_t mask; 87 88 if (!access_ok(VERIFY_READ, act, sizeof(*act)) || 89 __get_user(newk.sa.sa_handler, &act->sa_handler) || 90 __get_user(newk.sa.sa_restorer, &act->sa_restorer)) 91 return -EFAULT; 92 93 __get_user(newk.sa.sa_flags, &act->sa_flags); 94 __get_user(mask, &act->sa_mask); 95 siginitset(&newk.sa.sa_mask, mask); 96 } 97 98 retval = do_sigaction(signal, act ? &newk : NULL, oact ? &oldk : NULL); 99 100 if (!retval && oact) { 101 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) || 102 __put_user(oldk.sa.sa_handler, &oact->sa_handler) || 103 __put_user(oldk.sa.sa_restorer, &oact->sa_restorer)) 104 return -EFAULT; 105 106 __put_user(oldk.sa.sa_flags, &oact->sa_flags); 107 __put_user(oldk.sa.sa_mask.sig[0], &oact->sa_mask); 108 } 109 110 return retval; 111} 112 113int 114sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss) 115{ 116 return do_sigaltstack(uss, uoss, rdusp()); 117} 118 119static int 120restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc) 121{ 122 unsigned int err = 0; 123 unsigned long old_usp; 124 125 /* Always make any pending restarted system calls return -EINTR */ 126 current_thread_info()->restart_block.fn = do_no_restart_syscall; 127 128 /* 129 * Restore the registers from &sc->regs. sc is already checked 130 * for VERIFY_READ since the signal_frame was previously 131 * checked in sys_sigreturn(). 132 */ 133 if (__copy_from_user(regs, sc, sizeof(struct pt_regs))) 134 goto badframe; 135 136 /* Make that the user-mode flag is set. */ 137 regs->ccs |= (1 << (U_CCS_BITNR + CCS_SHIFT)); 138 139 /* Restore the old USP. */ 140 err |= __get_user(old_usp, &sc->usp); 141 wrusp(old_usp); 142 143 return err; 144 145badframe: 146 return 1; 147} 148 149/* Define some dummy arguments to be able to reach the regs argument. */ 150asmlinkage int 151sys_sigreturn(long r10, long r11, long r12, long r13, long mof, long srp, 152 struct pt_regs *regs) 153{ 154 sigset_t set; 155 struct signal_frame __user *frame; 156 unsigned long oldspc = regs->spc; 157 unsigned long oldccs = regs->ccs; 158 159 frame = (struct signal_frame *) rdusp(); 160 161 /* 162 * Since the signal is stacked on a dword boundary, the frame 163 * should be dword aligned here as well. It it's not, then the 164 * user is trying some funny business. 165 */ 166 if (((long)frame) & 3) 167 goto badframe; 168 169 if (!access_ok(VERIFY_READ, frame, sizeof(*frame))) 170 goto badframe; 171 172 if (__get_user(set.sig[0], &frame->sc.oldmask) || 173 (_NSIG_WORDS > 1 && __copy_from_user(&set.sig[1], 174 frame->extramask, 175 sizeof(frame->extramask)))) 176 goto badframe; 177 178 sigdelsetmask(&set, ~_BLOCKABLE); 179 spin_lock_irq(¤t->sighand->siglock); 180 181 current->blocked = set; 182 183 recalc_sigpending(); 184 spin_unlock_irq(¤t->sighand->siglock); 185 186 if (restore_sigcontext(regs, &frame->sc)) 187 goto badframe; 188 189 keep_debug_flags(oldccs, oldspc, regs); 190 191 return regs->r10; 192 193badframe: 194 force_sig(SIGSEGV, current); 195 return 0; 196} 197 198/* Define some dummy variables to be able to reach the regs argument. */ 199asmlinkage int 200sys_rt_sigreturn(long r10, long r11, long r12, long r13, long mof, long srp, 201 struct pt_regs *regs) 202{ 203 sigset_t set; 204 struct rt_signal_frame __user *frame; 205 unsigned long oldspc = regs->spc; 206 unsigned long oldccs = regs->ccs; 207 208 frame = (struct rt_signal_frame *) rdusp(); 209 210 /* 211 * Since the signal is stacked on a dword boundary, the frame 212 * should be dword aligned here as well. It it's not, then the 213 * user is trying some funny business. 214 */ 215 if (((long)frame) & 3) 216 goto badframe; 217 218 if (!access_ok(VERIFY_READ, frame, sizeof(*frame))) 219 goto badframe; 220 221 if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set))) 222 goto badframe; 223 224 sigdelsetmask(&set, ~_BLOCKABLE); 225 spin_lock_irq(¤t->sighand->siglock); 226 227 current->blocked = set; 228 229 recalc_sigpending(); 230 spin_unlock_irq(¤t->sighand->siglock); 231 232 if (restore_sigcontext(regs, &frame->uc.uc_mcontext)) 233 goto badframe; 234 235 if (do_sigaltstack(&frame->uc.uc_stack, NULL, rdusp()) == -EFAULT) 236 goto badframe; 237 238 keep_debug_flags(oldccs, oldspc, regs); 239 240 return regs->r10; 241 242badframe: 243 force_sig(SIGSEGV, current); 244 return 0; 245} 246 247/* Setup a signal frame. */ 248static int 249setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs, 250 unsigned long mask) 251{ 252 int err; 253 unsigned long usp; 254 255 err = 0; 256 usp = rdusp(); 257 258 /* 259 * Copy the registers. They are located first in sc, so it's 260 * possible to use sc directly. 261 */ 262 err |= __copy_to_user(sc, regs, sizeof(struct pt_regs)); 263 264 err |= __put_user(mask, &sc->oldmask); 265 err |= __put_user(usp, &sc->usp); 266 267 return err; 268} 269 270/* Figure out where to put the new signal frame - usually on the stack. */ 271static inline void __user * 272get_sigframe(struct k_sigaction *ka, struct pt_regs * regs, size_t frame_size) 273{ 274 unsigned long sp; 275 276 sp = rdusp(); 277 278 /* This is the X/Open sanctioned signal stack switching. */ 279 if (ka->sa.sa_flags & SA_ONSTACK) { 280 if (!on_sig_stack(sp)) 281 sp = current->sas_ss_sp + current->sas_ss_size; 282 } 283 284 /* Make sure the frame is dword-aligned. */ 285 sp &= ~3; 286 287 return (void __user *)(sp - frame_size); 288} 289 290/* Grab and setup a signal frame. 291 * 292 * Basically a lot of state-info is stacked, and arranged for the 293 * user-mode program to return to the kernel using either a trampiline 294 * which performs the syscall sigreturn(), or a provided user-mode 295 * trampoline. 296 */ 297static int 298setup_frame(int sig, struct k_sigaction *ka, sigset_t *set, 299 struct pt_regs * regs) 300{ 301 int err; 302 unsigned long return_ip; 303 struct signal_frame __user *frame; 304 305 err = 0; 306 frame = get_sigframe(ka, regs, sizeof(*frame)); 307 308 if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame))) 309 goto give_sigsegv; 310 311 err |= setup_sigcontext(&frame->sc, regs, set->sig[0]); 312 313 if (err) 314 goto give_sigsegv; 315 316 if (_NSIG_WORDS > 1) { 317 err |= __copy_to_user(frame->extramask, &set->sig[1], 318 sizeof(frame->extramask)); 319 } 320 321 if (err) 322 goto give_sigsegv; 323 324 /* 325 * Set up to return from user-space. If provided, use a stub 326 * already located in user-space. 327 */ 328 if (ka->sa.sa_flags & SA_RESTORER) { 329 return_ip = (unsigned long)ka->sa.sa_restorer; 330 } else { 331 /* Trampoline - the desired return ip is in the signal return page. */ 332 return_ip = cris_signal_return_page; 333 334 /* 335 * This is movu.w __NR_sigreturn, r9; break 13; 336 * 337 * WE DO NOT USE IT ANY MORE! It's only left here for historical 338 * reasons and because gdb uses it as a signature to notice 339 * signal handler stack frames. 340 */ 341 err |= __put_user(0x9c5f, (short __user*)(frame->retcode+0)); 342 err |= __put_user(__NR_sigreturn, (short __user*)(frame->retcode+2)); 343 err |= __put_user(0xe93d, (short __user*)(frame->retcode+4)); 344 } 345 346 if (err) 347 goto give_sigsegv; 348 349 /* 350 * Set up registers for signal handler. 351 * 352 * Where the code enters now. 353 * Where the code enter later. 354 * First argument, signo. 355 */ 356 regs->erp = (unsigned long) ka->sa.sa_handler; 357 regs->srp = return_ip; 358 regs->r10 = sig; 359 360 /* Actually move the USP to reflect the stacked frame. */ 361 wrusp((unsigned long)frame); 362 363 return 0; 364 365give_sigsegv: 366 if (sig == SIGSEGV) 367 ka->sa.sa_handler = SIG_DFL; 368 369 force_sig(SIGSEGV, current); 370 return -EFAULT; 371} 372 373static int 374setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info, 375 sigset_t *set, struct pt_regs * regs) 376{ 377 int err; 378 unsigned long return_ip; 379 struct rt_signal_frame __user *frame; 380 381 err = 0; 382 frame = get_sigframe(ka, regs, sizeof(*frame)); 383 384 if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame))) 385 goto give_sigsegv; 386 387 /* TODO: what is the current->exec_domain stuff and invmap ? */ 388 389 err |= __put_user(&frame->info, &frame->pinfo); 390 err |= __put_user(&frame->uc, &frame->puc); 391 err |= copy_siginfo_to_user(&frame->info, info); 392 393 if (err) 394 goto give_sigsegv; 395 396 /* Clear all the bits of the ucontext we don't use. */ 397 err |= __clear_user(&frame->uc, offsetof(struct ucontext, uc_mcontext)); 398 err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, set->sig[0]); 399 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)); 400 401 if (err) 402 goto give_sigsegv; 403 404 /* 405 * Set up to return from user-space. If provided, use a stub 406 * already located in user-space. 407 */ 408 if (ka->sa.sa_flags & SA_RESTORER) { 409 return_ip = (unsigned long) ka->sa.sa_restorer; 410 } else { 411 /* Trampoline - the desired return ip is in the signal return page. */ 412 return_ip = cris_signal_return_page + 6; 413 414 /* 415 * This is movu.w __NR_rt_sigreturn, r9; break 13; 416 * 417 * WE DO NOT USE IT ANY MORE! It's only left here for historical 418 * reasons and because gdb uses it as a signature to notice 419 * signal handler stack frames. 420 */ 421 err |= __put_user(0x9c5f, (short __user*)(frame->retcode+0)); 422 423 err |= __put_user(__NR_rt_sigreturn, 424 (short __user*)(frame->retcode+2)); 425 426 err |= __put_user(0xe93d, (short __user*)(frame->retcode+4)); 427 } 428 429 if (err) 430 goto give_sigsegv; 431 432 /* 433 * Set up registers for signal handler. 434 * 435 * Where the code enters now. 436 * Where the code enters later. 437 * First argument is signo. 438 * Second argument is (siginfo_t *). 439 * Third argument is unused. 440 */ 441 regs->erp = (unsigned long) ka->sa.sa_handler; 442 regs->srp = return_ip; 443 regs->r10 = sig; 444 regs->r11 = (unsigned long) &frame->info; 445 regs->r12 = 0; 446 447 /* Actually move the usp to reflect the stacked frame. */ 448 wrusp((unsigned long)frame); 449 450 return 0; 451 452give_sigsegv: 453 if (sig == SIGSEGV) 454 ka->sa.sa_handler = SIG_DFL; 455 456 force_sig(SIGSEGV, current); 457 return -EFAULT; 458} 459 460/* Invoke a signal handler to, well, handle the signal. */ 461static inline int 462handle_signal(int canrestart, unsigned long sig, 463 siginfo_t *info, struct k_sigaction *ka, 464 sigset_t *oldset, struct pt_regs * regs) 465{ 466 int ret; 467 468 /* Check if this got called from a system call. */ 469 if (canrestart) { 470 /* If so, check system call restarting. */ 471 switch (regs->r10) { 472 case -ERESTART_RESTARTBLOCK: 473 case -ERESTARTNOHAND: 474 /* 475 * This means that the syscall should 476 * only be restarted if there was no 477 * handler for the signal, and since 478 * this point isn't reached unless 479 * there is a handler, there's no need 480 * to restart. 481 */ 482 regs->r10 = -EINTR; 483 break; 484 485 case -ERESTARTSYS: 486 /* 487 * This means restart the syscall if 488 * there is no handler, or the handler 489 * was registered with SA_RESTART. 490 */ 491 if (!(ka->sa.sa_flags & SA_RESTART)) { 492 regs->r10 = -EINTR; 493 break; 494 } 495 496 /* Fall through. */ 497 498 case -ERESTARTNOINTR: 499 /* 500 * This means that the syscall should 501 * be called again after the signal 502 * handler returns. 503 */ 504 RESTART_CRIS_SYS(regs); 505 break; 506 } 507 } 508 509 /* Set up the stack frame. */ 510 if (ka->sa.sa_flags & SA_SIGINFO) 511 ret = setup_rt_frame(sig, ka, info, oldset, regs); 512 else 513 ret = setup_frame(sig, ka, oldset, regs); 514 515 if (ka->sa.sa_flags & SA_ONESHOT) 516 ka->sa.sa_handler = SIG_DFL; 517 518 if (ret == 0) { 519 spin_lock_irq(¤t->sighand->siglock); 520 sigorsets(¤t->blocked, ¤t->blocked, 521 &ka->sa.sa_mask); 522 if (!(ka->sa.sa_flags & SA_NODEFER)) 523 sigaddset(¤t->blocked, sig); 524 recalc_sigpending(); 525 spin_unlock_irq(¤t->sighand->siglock); 526 } 527 528 return ret; 529} 530 531/* 532 * Note that 'init' is a special process: it doesn't get signals it doesn't 533 * want to handle. Thus you cannot kill init even with a SIGKILL even by 534 * mistake. 535 * 536 * Also note that the regs structure given here as an argument, is the latest 537 * pushed pt_regs. It may or may not be the same as the first pushed registers 538 * when the initial usermode->kernelmode transition took place. Therefore 539 * we can use user_mode(regs) to see if we came directly from kernel or user 540 * mode below. 541 */ 542void 543do_signal(int canrestart, struct pt_regs *regs) 544{ 545 int signr; 546 siginfo_t info; 547 struct k_sigaction ka; 548 sigset_t *oldset; 549 550 /* 551 * The common case should go fast, which is why this point is 552 * reached from kernel-mode. If that's the case, just return 553 * without doing anything. 554 */ 555 if (!user_mode(regs)) 556 return; 557 558 if (test_thread_flag(TIF_RESTORE_SIGMASK)) 559 oldset = ¤t->saved_sigmask; 560 else 561 oldset = ¤t->blocked; 562 563 signr = get_signal_to_deliver(&info, &ka, regs, NULL); 564 565 if (signr > 0) { 566 /* Whee! Actually deliver the signal. */ 567 if (handle_signal(canrestart, signr, &info, &ka, 568 oldset, regs)) { 569 /* a signal was successfully delivered; the saved 570 * sigmask will have been stored in the signal frame, 571 * and will be restored by sigreturn, so we can simply 572 * clear the TIF_RESTORE_SIGMASK flag */ 573 if (test_thread_flag(TIF_RESTORE_SIGMASK)) 574 clear_thread_flag(TIF_RESTORE_SIGMASK); 575 } 576 577 return; 578 } 579 580 /* Got here from a system call? */ 581 if (canrestart) { 582 /* Restart the system call - no handlers present. */ 583 if (regs->r10 == -ERESTARTNOHAND || 584 regs->r10 == -ERESTARTSYS || 585 regs->r10 == -ERESTARTNOINTR) { 586 RESTART_CRIS_SYS(regs); 587 } 588 589 if (regs->r10 == -ERESTART_RESTARTBLOCK){ 590 regs->r9 = __NR_restart_syscall; 591 regs->erp -= 2; 592 } 593 } 594 595 /* if there's no signal to deliver, we just put the saved sigmask 596 * back */ 597 if (test_thread_flag(TIF_RESTORE_SIGMASK)) { 598 clear_thread_flag(TIF_RESTORE_SIGMASK); 599 sigprocmask(SIG_SETMASK, ¤t->saved_sigmask, NULL); 600 } 601} 602 603asmlinkage void 604ugdb_trap_user(struct thread_info *ti, int sig) 605{ 606 if (((user_regs(ti)->exs & 0xff00) >> 8) != SINGLE_STEP_INTR_VECT) { 607 /* Zero single-step PC if the reason we stopped wasn't a single 608 step exception. This is to avoid relying on it when it isn't 609 reliable. */ 610 user_regs(ti)->spc = 0; 611 } 612 if (((user_regs(ti)->exs & 0xff00) >> 8) == BREAK_8_INTR_VECT) { 613 /* Break 8: subtract 2 from ERP unless in a delay slot. */ 614 if (!(user_regs(ti)->erp & 0x1)) 615 user_regs(ti)->erp -= 2; 616 } 617 sys_kill(ti->task->pid, sig); 618} 619 620void 621keep_debug_flags(unsigned long oldccs, unsigned long oldspc, 622 struct pt_regs *regs) 623{ 624 if (oldccs & (1 << Q_CCS_BITNR)) { 625 /* Pending single step due to single-stepping the break 13 626 in the signal trampoline: keep the Q flag. */ 627 regs->ccs |= (1 << Q_CCS_BITNR); 628 /* S flag should be set - complain if it's not. */ 629 if (!(oldccs & (1 << (S_CCS_BITNR + CCS_SHIFT)))) { 630 printk("Q flag but no S flag?"); 631 } 632 regs->ccs |= (1 << (S_CCS_BITNR + CCS_SHIFT)); 633 /* Assume the SPC is valid and interesting. */ 634 regs->spc = oldspc; 635 636 } else if (oldccs & (1 << (S_CCS_BITNR + CCS_SHIFT))) { 637 /* If a h/w bp was set in the signal handler we need 638 to keep the S flag. */ 639 regs->ccs |= (1 << (S_CCS_BITNR + CCS_SHIFT)); 640 /* Don't keep the old SPC though; if we got here due to 641 a single-step, the Q flag should have been set. */ 642 } else if (regs->spc) { 643 /* If we were single-stepping *before* the signal was taken, 644 we don't want to restore that state now, because GDB will 645 have forgotten all about it. */ 646 regs->spc = 0; 647 regs->ccs &= ~(1 << (S_CCS_BITNR + CCS_SHIFT)); 648 } 649} 650 651/* Set up the trampolines on the signal return page. */ 652int __init 653cris_init_signal(void) 654{ 655 u16* data = kmalloc(PAGE_SIZE, GFP_KERNEL); 656 657 /* This is movu.w __NR_sigreturn, r9; break 13; */ 658 data[0] = 0x9c5f; 659 data[1] = __NR_sigreturn; 660 data[2] = 0xe93d; 661 /* This is movu.w __NR_rt_sigreturn, r9; break 13; */ 662 data[3] = 0x9c5f; 663 data[4] = __NR_rt_sigreturn; 664 data[5] = 0xe93d; 665 666 /* Map to userspace with appropriate permissions (no write access...) */ 667 cris_signal_return_page = (unsigned long) 668 __ioremap_prot(virt_to_phys(data), PAGE_SIZE, PAGE_SIGNAL_TRAMPOLINE); 669 670 return 0; 671} 672 673__initcall(cris_init_signal); 674