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 struct rt_sigframe 39 { 40 struct siginfo info; 41 struct ucontext uc; 42 struct { 43 xtregs_opt_t opt; 44 xtregs_user_t user; 45 #if XTENSA_HAVE_COPROCESSORS 46 xtregs_coprocessor_t cp; 47 #endif 48 } xtregs; 49 unsigned char retcode[6]; 50 unsigned int window[4]; 51 }; 52 53 /* 54 * Flush register windows stored in pt_regs to stack. 55 * Returns 1 for errors. 56 */ 57 58 int 59 flush_window_regs_user(struct pt_regs *regs) 60 { 61 const unsigned long ws = regs->windowstart; 62 const unsigned long wb = regs->windowbase; 63 unsigned long sp = 0; 64 unsigned long wm; 65 int err = 1; 66 int base; 67 68 /* Return if no other frames. */ 69 70 if (regs->wmask == 1) 71 return 0; 72 73 /* Rotate windowmask and skip empty frames. */ 74 75 wm = (ws >> wb) | (ws << (XCHAL_NUM_AREGS / 4 - wb)); 76 base = (XCHAL_NUM_AREGS / 4) - (regs->wmask >> 4); 77 78 /* For call8 or call12 frames, we need the previous stack pointer. */ 79 80 if ((regs->wmask & 2) == 0) 81 if (__get_user(sp, (int*)(regs->areg[base * 4 + 1] - 12))) 82 goto errout; 83 84 /* Spill frames to stack. */ 85 86 while (base < XCHAL_NUM_AREGS / 4) { 87 88 int m = (wm >> base); 89 int inc = 0; 90 91 /* Save registers a4..a7 (call8) or a4...a11 (call12) */ 92 93 if (m & 2) { /* call4 */ 94 inc = 1; 95 96 } else if (m & 4) { /* call8 */ 97 if (copy_to_user((void*)(sp - 32), 98 ®s->areg[(base + 1) * 4], 16)) 99 goto errout; 100 inc = 2; 101 102 } else if (m & 8) { /* call12 */ 103 if (copy_to_user((void*)(sp - 48), 104 ®s->areg[(base + 1) * 4], 32)) 105 goto errout; 106 inc = 3; 107 } 108 109 /* Save current frame a0..a3 under next SP */ 110 111 sp = regs->areg[((base + inc) * 4 + 1) % XCHAL_NUM_AREGS]; 112 if (copy_to_user((void*)(sp - 16), ®s->areg[base * 4], 16)) 113 goto errout; 114 115 /* Get current stack pointer for next loop iteration. */ 116 117 sp = regs->areg[base * 4 + 1]; 118 base += inc; 119 } 120 121 regs->wmask = 1; 122 regs->windowstart = 1 << wb; 123 124 return 0; 125 126 errout: 127 return err; 128 } 129 130 /* 131 * Note: We don't copy double exception 'regs', we have to finish double exc. 132 * first before we return to signal handler! This dbl.exc.handler might cause 133 * another double exception, but I think we are fine as the situation is the 134 * same as if we had returned to the signal handerl and got an interrupt 135 * immediately... 136 */ 137 138 static int 139 setup_sigcontext(struct rt_sigframe __user *frame, struct pt_regs *regs) 140 { 141 struct sigcontext __user *sc = &frame->uc.uc_mcontext; 142 struct thread_info *ti = current_thread_info(); 143 int err = 0; 144 145 #define COPY(x) err |= __put_user(regs->x, &sc->sc_##x) 146 COPY(pc); 147 COPY(ps); 148 COPY(lbeg); 149 COPY(lend); 150 COPY(lcount); 151 COPY(sar); 152 #undef COPY 153 154 err |= flush_window_regs_user(regs); 155 err |= __copy_to_user (sc->sc_a, regs->areg, 16 * 4); 156 err |= __put_user(0, &sc->sc_xtregs); 157 158 if (err) 159 return err; 160 161 #if XTENSA_HAVE_COPROCESSORS 162 coprocessor_flush_all(ti); 163 coprocessor_release_all(ti); 164 err |= __copy_to_user(&frame->xtregs.cp, &ti->xtregs_cp, 165 sizeof (frame->xtregs.cp)); 166 #endif 167 err |= __copy_to_user(&frame->xtregs.opt, ®s->xtregs_opt, 168 sizeof (xtregs_opt_t)); 169 err |= __copy_to_user(&frame->xtregs.user, &ti->xtregs_user, 170 sizeof (xtregs_user_t)); 171 172 err |= __put_user(err ? NULL : &frame->xtregs, &sc->sc_xtregs); 173 174 return err; 175 } 176 177 static int 178 restore_sigcontext(struct pt_regs *regs, struct rt_sigframe __user *frame) 179 { 180 struct sigcontext __user *sc = &frame->uc.uc_mcontext; 181 struct thread_info *ti = current_thread_info(); 182 unsigned int err = 0; 183 unsigned long ps; 184 185 #define COPY(x) err |= __get_user(regs->x, &sc->sc_##x) 186 COPY(pc); 187 COPY(lbeg); 188 COPY(lend); 189 COPY(lcount); 190 COPY(sar); 191 #undef COPY 192 193 /* All registers were flushed to stack. Start with a prestine frame. */ 194 195 regs->wmask = 1; 196 regs->windowbase = 0; 197 regs->windowstart = 1; 198 199 regs->syscall = -1; /* disable syscall checks */ 200 201 /* For PS, restore only PS.CALLINC. 202 * Assume that all other bits are either the same as for the signal 203 * handler, or the user mode value doesn't matter (e.g. PS.OWB). 204 */ 205 err |= __get_user(ps, &sc->sc_ps); 206 regs->ps = (regs->ps & ~PS_CALLINC_MASK) | (ps & PS_CALLINC_MASK); 207 208 /* Additional corruption checks */ 209 210 if ((regs->lcount > 0) 211 && ((regs->lbeg > TASK_SIZE) || (regs->lend > TASK_SIZE)) ) 212 err = 1; 213 214 err |= __copy_from_user(regs->areg, sc->sc_a, 16 * 4); 215 216 if (err) 217 return err; 218 219 /* The signal handler may have used coprocessors in which 220 * case they are still enabled. We disable them to force a 221 * reloading of the original task's CP state by the lazy 222 * context-switching mechanisms of CP exception handling. 223 * Also, we essentially discard any coprocessor state that the 224 * signal handler created. */ 225 226 #if XTENSA_HAVE_COPROCESSORS 227 coprocessor_release_all(ti); 228 err |= __copy_from_user(&ti->xtregs_cp, &frame->xtregs.cp, 229 sizeof (frame->xtregs.cp)); 230 #endif 231 err |= __copy_from_user(&ti->xtregs_user, &frame->xtregs.user, 232 sizeof (xtregs_user_t)); 233 err |= __copy_from_user(®s->xtregs_opt, &frame->xtregs.opt, 234 sizeof (xtregs_opt_t)); 235 236 return err; 237 } 238 239 240 /* 241 * Do a signal return; undo the signal stack. 242 */ 243 244 asmlinkage long xtensa_rt_sigreturn(long a0, long a1, long a2, long a3, 245 long a4, long a5, struct pt_regs *regs) 246 { 247 struct rt_sigframe __user *frame; 248 sigset_t set; 249 int ret; 250 251 if (regs->depc > 64) 252 panic("rt_sigreturn in double exception!\n"); 253 254 frame = (struct rt_sigframe __user *) regs->areg[1]; 255 256 if (!access_ok(VERIFY_READ, frame, sizeof(*frame))) 257 goto badframe; 258 259 if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set))) 260 goto badframe; 261 262 sigdelsetmask(&set, ~_BLOCKABLE); 263 set_current_blocked(&set); 264 265 if (restore_sigcontext(regs, frame)) 266 goto badframe; 267 268 ret = regs->areg[2]; 269 270 if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->areg[1]) == -EFAULT) 271 goto badframe; 272 273 return ret; 274 275 badframe: 276 force_sig(SIGSEGV, current); 277 return 0; 278 } 279 280 281 282 /* 283 * Set up a signal frame. 284 */ 285 286 static int 287 gen_return_code(unsigned char *codemem) 288 { 289 int err = 0; 290 291 /* 292 * The 12-bit immediate is really split up within the 24-bit MOVI 293 * instruction. As long as the above system call numbers fit within 294 * 8-bits, the following code works fine. See the Xtensa ISA for 295 * details. 296 */ 297 298 #if __NR_rt_sigreturn > 255 299 # error Generating the MOVI instruction below breaks! 300 #endif 301 302 #ifdef __XTENSA_EB__ /* Big Endian version */ 303 /* Generate instruction: MOVI a2, __NR_rt_sigreturn */ 304 err |= __put_user(0x22, &codemem[0]); 305 err |= __put_user(0x0a, &codemem[1]); 306 err |= __put_user(__NR_rt_sigreturn, &codemem[2]); 307 /* Generate instruction: SYSCALL */ 308 err |= __put_user(0x00, &codemem[3]); 309 err |= __put_user(0x05, &codemem[4]); 310 err |= __put_user(0x00, &codemem[5]); 311 312 #elif defined __XTENSA_EL__ /* Little Endian version */ 313 /* Generate instruction: MOVI a2, __NR_rt_sigreturn */ 314 err |= __put_user(0x22, &codemem[0]); 315 err |= __put_user(0xa0, &codemem[1]); 316 err |= __put_user(__NR_rt_sigreturn, &codemem[2]); 317 /* Generate instruction: SYSCALL */ 318 err |= __put_user(0x00, &codemem[3]); 319 err |= __put_user(0x50, &codemem[4]); 320 err |= __put_user(0x00, &codemem[5]); 321 #else 322 # error Must use compiler for Xtensa processors. 323 #endif 324 325 /* Flush generated code out of the data cache */ 326 327 if (err == 0) { 328 __invalidate_icache_range((unsigned long)codemem, 6UL); 329 __flush_invalidate_dcache_range((unsigned long)codemem, 6UL); 330 } 331 332 return err; 333 } 334 335 336 static int setup_frame(int sig, struct k_sigaction *ka, siginfo_t *info, 337 sigset_t *set, struct pt_regs *regs) 338 { 339 struct rt_sigframe *frame; 340 int err = 0; 341 int signal; 342 unsigned long sp, ra; 343 344 sp = regs->areg[1]; 345 346 if ((ka->sa.sa_flags & SA_ONSTACK) != 0 && ! on_sig_stack(sp)) { 347 sp = current->sas_ss_sp + current->sas_ss_size; 348 } 349 350 frame = (void *)((sp - sizeof(*frame)) & -16ul); 351 352 if (regs->depc > 64) 353 panic ("Double exception sys_sigreturn\n"); 354 355 if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame))) { 356 goto give_sigsegv; 357 } 358 359 signal = current_thread_info()->exec_domain 360 && current_thread_info()->exec_domain->signal_invmap 361 && sig < 32 362 ? current_thread_info()->exec_domain->signal_invmap[sig] 363 : sig; 364 365 if (ka->sa.sa_flags & SA_SIGINFO) { 366 err |= copy_siginfo_to_user(&frame->info, info); 367 } 368 369 /* Create the user context. */ 370 371 err |= __put_user(0, &frame->uc.uc_flags); 372 err |= __put_user(0, &frame->uc.uc_link); 373 err |= __put_user((void *)current->sas_ss_sp, 374 &frame->uc.uc_stack.ss_sp); 375 err |= __put_user(sas_ss_flags(regs->areg[1]), 376 &frame->uc.uc_stack.ss_flags); 377 err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size); 378 err |= setup_sigcontext(frame, regs); 379 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)); 380 381 if (ka->sa.sa_flags & SA_RESTORER) { 382 ra = (unsigned long)ka->sa.sa_restorer; 383 } else { 384 385 /* Create sys_rt_sigreturn syscall in stack frame */ 386 387 err |= gen_return_code(frame->retcode); 388 389 if (err) { 390 goto give_sigsegv; 391 } 392 ra = (unsigned long) frame->retcode; 393 } 394 395 /* 396 * Create signal handler execution context. 397 * Return context not modified until this point. 398 */ 399 400 /* Set up registers for signal handler */ 401 start_thread(regs, (unsigned long) ka->sa.sa_handler, 402 (unsigned long) frame); 403 404 /* Set up a stack frame for a call4 405 * Note: PS.CALLINC is set to one by start_thread 406 */ 407 regs->areg[4] = (((unsigned long) ra) & 0x3fffffff) | 0x40000000; 408 regs->areg[6] = (unsigned long) signal; 409 regs->areg[7] = (unsigned long) &frame->info; 410 regs->areg[8] = (unsigned long) &frame->uc; 411 412 /* Set access mode to USER_DS. Nomenclature is outdated, but 413 * functionality is used in uaccess.h 414 */ 415 set_fs(USER_DS); 416 417 #if DEBUG_SIG 418 printk("SIG rt deliver (%s:%d): signal=%d sp=%p pc=%08x\n", 419 current->comm, current->pid, signal, frame, regs->pc); 420 #endif 421 422 return 0; 423 424 give_sigsegv: 425 force_sigsegv(sig, current); 426 return -EFAULT; 427 } 428 429 /* 430 * Atomically swap in the new signal mask, and wait for a signal. 431 */ 432 433 asmlinkage long xtensa_rt_sigsuspend(sigset_t __user *unewset, 434 size_t sigsetsize, 435 long a2, long a3, long a4, long a5, 436 struct pt_regs *regs) 437 { 438 sigset_t saveset, newset; 439 440 /* XXX: Don't preclude handling different sized sigset_t's. */ 441 if (sigsetsize != sizeof(sigset_t)) 442 return -EINVAL; 443 444 if (copy_from_user(&newset, unewset, sizeof(newset))) 445 return -EFAULT; 446 447 sigdelsetmask(&newset, ~_BLOCKABLE); 448 saveset = current->blocked; 449 set_current_blocked(&newset); 450 451 regs->areg[2] = -EINTR; 452 while (1) { 453 current->state = TASK_INTERRUPTIBLE; 454 schedule(); 455 if (do_signal(regs, &saveset)) 456 return -EINTR; 457 } 458 } 459 460 asmlinkage long xtensa_sigaltstack(const stack_t __user *uss, 461 stack_t __user *uoss, 462 long a2, long a3, long a4, long a5, 463 struct pt_regs *regs) 464 { 465 return do_sigaltstack(uss, uoss, regs->areg[1]); 466 } 467 468 469 470 /* 471 * Note that 'init' is a special process: it doesn't get signals it doesn't 472 * want to handle. Thus you cannot kill init even with a SIGKILL even by 473 * mistake. 474 * 475 * Note that we go through the signals twice: once to check the signals that 476 * the kernel can handle, and then we build all the user-level signal handling 477 * stack-frames in one go after that. 478 */ 479 int do_signal(struct pt_regs *regs, sigset_t *oldset) 480 { 481 siginfo_t info; 482 int signr; 483 struct k_sigaction ka; 484 485 if (!user_mode(regs)) 486 return 0; 487 488 if (try_to_freeze()) 489 goto no_signal; 490 491 if (!oldset) 492 oldset = ¤t->blocked; 493 494 task_pt_regs(current)->icountlevel = 0; 495 496 signr = get_signal_to_deliver(&info, &ka, regs, NULL); 497 498 if (signr > 0) { 499 int ret; 500 501 /* Are we from a system call? */ 502 503 if ((signed)regs->syscall >= 0) { 504 505 /* If so, check system call restarting.. */ 506 507 switch (regs->areg[2]) { 508 case -ERESTARTNOHAND: 509 case -ERESTART_RESTARTBLOCK: 510 regs->areg[2] = -EINTR; 511 break; 512 513 case -ERESTARTSYS: 514 if (!(ka.sa.sa_flags & SA_RESTART)) { 515 regs->areg[2] = -EINTR; 516 break; 517 } 518 /* fallthrough */ 519 case -ERESTARTNOINTR: 520 regs->areg[2] = regs->syscall; 521 regs->pc -= 3; 522 break; 523 524 default: 525 /* nothing to do */ 526 if (regs->areg[2] != 0) 527 break; 528 } 529 } 530 531 /* Whee! Actually deliver the signal. */ 532 /* Set up the stack frame */ 533 ret = setup_frame(signr, &ka, &info, oldset, regs); 534 if (ret) 535 return ret; 536 537 block_sigmask(&ka, signr); 538 if (current->ptrace & PT_SINGLESTEP) 539 task_pt_regs(current)->icountlevel = 1; 540 541 return 1; 542 } 543 544 no_signal: 545 /* Did we come from a system call? */ 546 if ((signed) regs->syscall >= 0) { 547 /* Restart the system call - no handlers present */ 548 switch (regs->areg[2]) { 549 case -ERESTARTNOHAND: 550 case -ERESTARTSYS: 551 case -ERESTARTNOINTR: 552 regs->areg[2] = regs->syscall; 553 regs->pc -= 3; 554 break; 555 case -ERESTART_RESTARTBLOCK: 556 regs->areg[2] = __NR_restart_syscall; 557 regs->pc -= 3; 558 break; 559 } 560 } 561 if (current->ptrace & PT_SINGLESTEP) 562 task_pt_regs(current)->icountlevel = 1; 563 return 0; 564 } 565 566