1 /* 2 * arch/xtensa/kernel/signal.c 3 * 4 * Default platform functions. 5 * 6 * This file is subject to the terms and conditions of the GNU General Public 7 * License. See the file "COPYING" in the main directory of this archive 8 * for more details. 9 * 10 * Copyright (C) 2005, 2006 Tensilica Inc. 11 * Copyright (C) 1991, 1992 Linus Torvalds 12 * 1997-11-28 Modified for POSIX.1b signals by Richard Henderson 13 * 14 * Chris Zankel <chris@zankel.net> 15 * Joe Taylor <joe@tensilica.com> 16 */ 17 18 #include <linux/signal.h> 19 #include <linux/errno.h> 20 #include <linux/ptrace.h> 21 #include <linux/personality.h> 22 #include <linux/freezer.h> 23 24 #include <asm/ucontext.h> 25 #include <asm/uaccess.h> 26 #include <asm/cacheflush.h> 27 #include <asm/coprocessor.h> 28 #include <asm/unistd.h> 29 30 #define DEBUG_SIG 0 31 32 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP))) 33 34 asmlinkage int do_signal(struct pt_regs *regs, sigset_t *oldset); 35 36 extern struct task_struct *coproc_owners[]; 37 38 extern void release_all_cp (struct task_struct *); 39 40 struct rt_sigframe 41 { 42 struct siginfo info; 43 struct ucontext uc; 44 cp_state_t cpstate; 45 unsigned char retcode[6]; 46 unsigned int window[4]; 47 }; 48 49 /* 50 * Flush register windows stored in pt_regs to stack. 51 * Returns 1 for errors. 52 * 53 * Note that windowbase, windowstart, and wmask are not updated! 54 */ 55 56 int 57 flush_window_regs_user(struct pt_regs *regs) 58 { 59 const unsigned long ws = regs->windowstart; 60 const unsigned long wb = regs->windowbase; 61 unsigned long sp = 0; 62 unsigned long wm; 63 int err = 1; 64 int base; 65 66 /* Return if no other frames. */ 67 68 if (regs->wmask == 1) 69 return 0; 70 71 /* Rotate windowmask and skip empty frames. */ 72 73 wm = (ws >> wb) | (ws << (XCHAL_NUM_AREGS / 4 - wb)); 74 base = (XCHAL_NUM_AREGS / 4) - (regs->wmask >> 4); 75 76 /* For call8 or call12 frames, we need the previous stack pointer. */ 77 78 if ((regs->wmask & 2) == 0) 79 if (__get_user(sp, (int*)(regs->areg[base * 4 + 1] - 12))) 80 goto errout; 81 82 /* Spill frames to stack. */ 83 84 while (base < XCHAL_NUM_AREGS / 4) { 85 86 int m = (wm >> base); 87 int inc = 0; 88 89 /* Save registers a4..a7 (call8) or a4...a11 (call12) */ 90 91 if (m & 2) { /* call4 */ 92 inc = 1; 93 94 } else if (m & 4) { /* call8 */ 95 if (copy_to_user((void*)(sp - 32), 96 ®s->areg[(base + 1) * 4], 16)) 97 goto errout; 98 inc = 2; 99 100 } else if (m & 8) { /* call12 */ 101 if (copy_to_user((void*)(sp - 48), 102 ®s->areg[(base + 1) * 4], 32)) 103 goto errout; 104 inc = 3; 105 } 106 107 /* Save current frame a0..a3 under next SP */ 108 109 sp = regs->areg[((base + inc) * 4 + 1) % XCHAL_NUM_AREGS]; 110 if (copy_to_user((void*)(sp - 16), ®s->areg[base * 4], 16)) 111 goto errout; 112 113 /* Get current stack pointer for next loop iteration. */ 114 115 sp = regs->areg[base * 4 + 1]; 116 base += inc; 117 } 118 119 return 0; 120 121 errout: 122 return err; 123 } 124 125 /* 126 * Note: We don't copy double exception 'regs', we have to finish double exc. 127 * first before we return to signal handler! This dbl.exc.handler might cause 128 * another double exception, but I think we are fine as the situation is the 129 * same as if we had returned to the signal handerl and got an interrupt 130 * immediately... 131 */ 132 133 static int 134 setup_sigcontext(struct sigcontext __user *sc, cp_state_t *cpstate, 135 struct pt_regs *regs, unsigned long mask) 136 { 137 int err = 0; 138 139 #define COPY(x) err |= __put_user(regs->x, &sc->sc_##x) 140 COPY(pc); 141 COPY(ps); 142 COPY(lbeg); 143 COPY(lend); 144 COPY(lcount); 145 COPY(sar); 146 #undef COPY 147 148 err |= flush_window_regs_user(regs); 149 err |= __copy_to_user (sc->sc_a, regs->areg, 16 * 4); 150 151 // err |= __copy_to_user (sc->sc_a, regs->areg, XCHAL_NUM_AREGS * 4) 152 153 #if XCHAL_HAVE_CP 154 # error Coprocessors unsupported 155 err |= save_cpextra(cpstate); 156 err |= __put_user(err ? NULL : cpstate, &sc->sc_cpstate); 157 #endif 158 /* non-iBCS2 extensions.. */ 159 err |= __put_user(mask, &sc->oldmask); 160 161 return err; 162 } 163 164 static int 165 restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc) 166 { 167 unsigned int err = 0; 168 unsigned long ps; 169 170 #define COPY(x) err |= __get_user(regs->x, &sc->sc_##x) 171 COPY(pc); 172 COPY(lbeg); 173 COPY(lend); 174 COPY(lcount); 175 COPY(sar); 176 #undef COPY 177 178 /* All registers were flushed to stack. Start with a prestine frame. */ 179 180 regs->wmask = 1; 181 regs->windowbase = 0; 182 regs->windowstart = 1; 183 184 /* For PS, restore only PS.CALLINC. 185 * Assume that all other bits are either the same as for the signal 186 * handler, or the user mode value doesn't matter (e.g. PS.OWB). 187 */ 188 err |= __get_user(ps, &sc->sc_ps); 189 regs->ps = (regs->ps & ~PS_CALLINC_MASK) | (ps & PS_CALLINC_MASK); 190 191 /* Additional corruption checks */ 192 193 if ((regs->lcount > 0) 194 && ((regs->lbeg > TASK_SIZE) || (regs->lend > TASK_SIZE)) ) 195 err = 1; 196 197 err |= __copy_from_user(regs->areg, sc->sc_a, 16 * 4); 198 199 #if XCHAL_HAVE_CP 200 # error Coprocessors unsupported 201 /* The signal handler may have used coprocessors in which 202 * case they are still enabled. We disable them to force a 203 * reloading of the original task's CP state by the lazy 204 * context-switching mechanisms of CP exception handling. 205 * Also, we essentially discard any coprocessor state that the 206 * signal handler created. */ 207 208 if (!err) { 209 struct task_struct *tsk = current; 210 release_all_cp(tsk); 211 err |= __copy_from_user(tsk->thread.cpextra, sc->sc_cpstate, 212 XTENSA_CP_EXTRA_SIZE); 213 } 214 #endif 215 216 regs->syscall = -1; /* disable syscall checks */ 217 return err; 218 } 219 220 221 222 /* 223 * Do a signal return; undo the signal stack. 224 */ 225 226 asmlinkage long xtensa_rt_sigreturn(long a0, long a1, long a2, long a3, 227 long a4, long a5, struct pt_regs *regs) 228 { 229 struct rt_sigframe __user *frame; 230 sigset_t set; 231 int ret; 232 233 if (regs->depc > 64) 234 panic("rt_sigreturn in double exception!\n"); 235 236 frame = (struct rt_sigframe __user *) regs->areg[1]; 237 238 if (!access_ok(VERIFY_READ, frame, sizeof(*frame))) 239 goto badframe; 240 241 if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set))) 242 goto badframe; 243 244 sigdelsetmask(&set, ~_BLOCKABLE); 245 spin_lock_irq(¤t->sighand->siglock); 246 current->blocked = set; 247 recalc_sigpending(); 248 spin_unlock_irq(¤t->sighand->siglock); 249 250 if (restore_sigcontext(regs, &frame->uc.uc_mcontext)) 251 goto badframe; 252 253 ret = regs->areg[2]; 254 255 if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->areg[1]) == -EFAULT) 256 goto badframe; 257 258 return ret; 259 260 badframe: 261 force_sig(SIGSEGV, current); 262 return 0; 263 } 264 265 266 267 /* 268 * Set up a signal frame. 269 */ 270 271 static int 272 gen_return_code(unsigned char *codemem) 273 { 274 int err = 0; 275 276 /* 277 * The 12-bit immediate is really split up within the 24-bit MOVI 278 * instruction. As long as the above system call numbers fit within 279 * 8-bits, the following code works fine. See the Xtensa ISA for 280 * details. 281 */ 282 283 #if __NR_rt_sigreturn > 255 284 # error Generating the MOVI instruction below breaks! 285 #endif 286 287 #ifdef __XTENSA_EB__ /* Big Endian version */ 288 /* Generate instruction: MOVI a2, __NR_rt_sigreturn */ 289 err |= __put_user(0x22, &codemem[0]); 290 err |= __put_user(0x0a, &codemem[1]); 291 err |= __put_user(__NR_rt_sigreturn, &codemem[2]); 292 /* Generate instruction: SYSCALL */ 293 err |= __put_user(0x00, &codemem[3]); 294 err |= __put_user(0x05, &codemem[4]); 295 err |= __put_user(0x00, &codemem[5]); 296 297 #elif defined __XTENSA_EL__ /* Little Endian version */ 298 /* Generate instruction: MOVI a2, __NR_rt_sigreturn */ 299 err |= __put_user(0x22, &codemem[0]); 300 err |= __put_user(0xa0, &codemem[1]); 301 err |= __put_user(__NR_rt_sigreturn, &codemem[2]); 302 /* Generate instruction: SYSCALL */ 303 err |= __put_user(0x00, &codemem[3]); 304 err |= __put_user(0x50, &codemem[4]); 305 err |= __put_user(0x00, &codemem[5]); 306 #else 307 # error Must use compiler for Xtensa processors. 308 #endif 309 310 /* Flush generated code out of the data cache */ 311 312 if (err == 0) { 313 __invalidate_icache_range((unsigned long)codemem, 6UL); 314 __flush_invalidate_dcache_range((unsigned long)codemem, 6UL); 315 } 316 317 return err; 318 } 319 320 321 static void setup_frame(int sig, struct k_sigaction *ka, siginfo_t *info, 322 sigset_t *set, struct pt_regs *regs) 323 { 324 struct rt_sigframe *frame; 325 int err = 0; 326 int signal; 327 unsigned long sp, ra; 328 329 sp = regs->areg[1]; 330 331 if ((ka->sa.sa_flags & SA_ONSTACK) != 0 && ! on_sig_stack(sp)) { 332 sp = current->sas_ss_sp + current->sas_ss_size; 333 } 334 335 frame = (void *)((sp - sizeof(*frame)) & -16ul); 336 337 if (regs->depc > 64) 338 panic ("Double exception sys_sigreturn\n"); 339 340 if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame))) { 341 goto give_sigsegv; 342 } 343 344 signal = current_thread_info()->exec_domain 345 && current_thread_info()->exec_domain->signal_invmap 346 && sig < 32 347 ? current_thread_info()->exec_domain->signal_invmap[sig] 348 : sig; 349 350 if (ka->sa.sa_flags & SA_SIGINFO) { 351 err |= copy_siginfo_to_user(&frame->info, info); 352 } 353 354 /* Create the user context. */ 355 356 err |= __put_user(0, &frame->uc.uc_flags); 357 err |= __put_user(0, &frame->uc.uc_link); 358 err |= __put_user((void *)current->sas_ss_sp, 359 &frame->uc.uc_stack.ss_sp); 360 err |= __put_user(sas_ss_flags(regs->areg[1]), 361 &frame->uc.uc_stack.ss_flags); 362 err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size); 363 err |= setup_sigcontext(&frame->uc.uc_mcontext, &frame->cpstate, 364 regs, set->sig[0]); 365 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)); 366 367 /* Create sys_rt_sigreturn syscall in stack frame */ 368 369 err |= gen_return_code(frame->retcode); 370 371 if (err) { 372 goto give_sigsegv; 373 } 374 375 376 /* 377 * Create signal handler execution context. 378 * Return context not modified until this point. 379 */ 380 381 /* Set up registers for signal handler */ 382 start_thread(regs, (unsigned long) ka->sa.sa_handler, 383 (unsigned long) frame); 384 385 /* Set up a stack frame for a call4 386 * Note: PS.CALLINC is set to one by start_thread 387 */ 388 ra = (unsigned long) frame->retcode; 389 regs->areg[4] = (((unsigned long) ra) & 0x3fffffff) | 0x40000000; 390 regs->areg[6] = (unsigned long) signal; 391 regs->areg[7] = (unsigned long) &frame->info; 392 regs->areg[8] = (unsigned long) &frame->uc; 393 394 /* Set access mode to USER_DS. Nomenclature is outdated, but 395 * functionality is used in uaccess.h 396 */ 397 set_fs(USER_DS); 398 399 #if DEBUG_SIG 400 printk("SIG rt deliver (%s:%d): signal=%d sp=%p pc=%08x\n", 401 current->comm, current->pid, signal, frame, regs->pc); 402 #endif 403 404 return; 405 406 give_sigsegv: 407 if (sig == SIGSEGV) 408 ka->sa.sa_handler = SIG_DFL; 409 force_sig(SIGSEGV, current); 410 } 411 412 /* 413 * Atomically swap in the new signal mask, and wait for a signal. 414 */ 415 416 asmlinkage long xtensa_rt_sigsuspend(sigset_t __user *unewset, 417 size_t sigsetsize, 418 long a2, long a3, long a4, long a5, 419 struct pt_regs *regs) 420 { 421 sigset_t saveset, newset; 422 423 /* XXX: Don't preclude handling different sized sigset_t's. */ 424 if (sigsetsize != sizeof(sigset_t)) 425 return -EINVAL; 426 427 if (copy_from_user(&newset, unewset, sizeof(newset))) 428 return -EFAULT; 429 430 sigdelsetmask(&newset, ~_BLOCKABLE); 431 spin_lock_irq(¤t->sighand->siglock); 432 saveset = current->blocked; 433 current->blocked = newset; 434 recalc_sigpending(); 435 spin_unlock_irq(¤t->sighand->siglock); 436 437 regs->areg[2] = -EINTR; 438 while (1) { 439 current->state = TASK_INTERRUPTIBLE; 440 schedule(); 441 if (do_signal(regs, &saveset)) 442 return -EINTR; 443 } 444 } 445 446 asmlinkage long xtensa_sigaltstack(const stack_t __user *uss, 447 stack_t __user *uoss, 448 long a2, long a3, long a4, long a5, 449 struct pt_regs *regs) 450 { 451 return do_sigaltstack(uss, uoss, regs->areg[1]); 452 } 453 454 455 456 /* 457 * Note that 'init' is a special process: it doesn't get signals it doesn't 458 * want to handle. Thus you cannot kill init even with a SIGKILL even by 459 * mistake. 460 * 461 * Note that we go through the signals twice: once to check the signals that 462 * the kernel can handle, and then we build all the user-level signal handling 463 * stack-frames in one go after that. 464 */ 465 int do_signal(struct pt_regs *regs, sigset_t *oldset) 466 { 467 siginfo_t info; 468 int signr; 469 struct k_sigaction ka; 470 471 if (!user_mode(regs)) 472 return 0; 473 474 if (try_to_freeze()) 475 goto no_signal; 476 477 if (!oldset) 478 oldset = ¤t->blocked; 479 480 task_pt_regs(current)->icountlevel = 0; 481 482 signr = get_signal_to_deliver(&info, &ka, regs, NULL); 483 484 if (signr > 0) { 485 486 /* Are we from a system call? */ 487 488 if ((signed)regs->syscall >= 0) { 489 490 /* If so, check system call restarting.. */ 491 492 switch (regs->areg[2]) { 493 case -ERESTARTNOHAND: 494 case -ERESTART_RESTARTBLOCK: 495 regs->areg[2] = -EINTR; 496 break; 497 498 case -ERESTARTSYS: 499 if (!(ka.sa.sa_flags & SA_RESTART)) { 500 regs->areg[2] = -EINTR; 501 break; 502 } 503 /* fallthrough */ 504 case -ERESTARTNOINTR: 505 regs->areg[2] = regs->syscall; 506 regs->pc -= 3; 507 break; 508 509 default: 510 /* nothing to do */ 511 if (regs->areg[2] != 0) 512 break; 513 } 514 } 515 516 /* Whee! Actually deliver the signal. */ 517 /* Set up the stack frame */ 518 setup_frame(signr, &ka, &info, oldset, regs); 519 520 if (ka.sa.sa_flags & SA_ONESHOT) 521 ka.sa.sa_handler = SIG_DFL; 522 523 spin_lock_irq(¤t->sighand->siglock); 524 sigorsets(¤t->blocked, ¤t->blocked, &ka.sa.sa_mask); 525 if (!(ka.sa.sa_flags & SA_NODEFER)) 526 sigaddset(¤t->blocked, signr); 527 recalc_sigpending(); 528 spin_unlock_irq(¤t->sighand->siglock); 529 if (current->ptrace & PT_SINGLESTEP) 530 task_pt_regs(current)->icountlevel = 1; 531 532 return 1; 533 } 534 535 no_signal: 536 /* Did we come from a system call? */ 537 if ((signed) regs->syscall >= 0) { 538 /* Restart the system call - no handlers present */ 539 switch (regs->areg[2]) { 540 case -ERESTARTNOHAND: 541 case -ERESTARTSYS: 542 case -ERESTARTNOINTR: 543 regs->areg[2] = regs->syscall; 544 regs->pc -= 3; 545 break; 546 case -ERESTART_RESTARTBLOCK: 547 regs->areg[2] = __NR_restart_syscall; 548 regs->pc -= 3; 549 break; 550 } 551 } 552 if (current->ptrace & PT_SINGLESTEP) 553 task_pt_regs(current)->icountlevel = 1; 554 return 0; 555 } 556 557