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/tracehook.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 extern struct task_struct *coproc_owners[]; 33 34 struct rt_sigframe 35 { 36 struct siginfo info; 37 struct ucontext uc; 38 struct { 39 xtregs_opt_t opt; 40 xtregs_user_t user; 41 #if XTENSA_HAVE_COPROCESSORS 42 xtregs_coprocessor_t cp; 43 #endif 44 } xtregs; 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 54 int 55 flush_window_regs_user(struct pt_regs *regs) 56 { 57 const unsigned long ws = regs->windowstart; 58 const unsigned long wb = regs->windowbase; 59 unsigned long sp = 0; 60 unsigned long wm; 61 int err = 1; 62 int base; 63 64 /* Return if no other frames. */ 65 66 if (regs->wmask == 1) 67 return 0; 68 69 /* Rotate windowmask and skip empty frames. */ 70 71 wm = (ws >> wb) | (ws << (XCHAL_NUM_AREGS / 4 - wb)); 72 base = (XCHAL_NUM_AREGS / 4) - (regs->wmask >> 4); 73 74 /* For call8 or call12 frames, we need the previous stack pointer. */ 75 76 if ((regs->wmask & 2) == 0) 77 if (__get_user(sp, (int*)(regs->areg[base * 4 + 1] - 12))) 78 goto errout; 79 80 /* Spill frames to stack. */ 81 82 while (base < XCHAL_NUM_AREGS / 4) { 83 84 int m = (wm >> base); 85 int inc = 0; 86 87 /* Save registers a4..a7 (call8) or a4...a11 (call12) */ 88 89 if (m & 2) { /* call4 */ 90 inc = 1; 91 92 } else if (m & 4) { /* call8 */ 93 if (copy_to_user((void*)(sp - 32), 94 ®s->areg[(base + 1) * 4], 16)) 95 goto errout; 96 inc = 2; 97 98 } else if (m & 8) { /* call12 */ 99 if (copy_to_user((void*)(sp - 48), 100 ®s->areg[(base + 1) * 4], 32)) 101 goto errout; 102 inc = 3; 103 } 104 105 /* Save current frame a0..a3 under next SP */ 106 107 sp = regs->areg[((base + inc) * 4 + 1) % XCHAL_NUM_AREGS]; 108 if (copy_to_user((void*)(sp - 16), ®s->areg[base * 4], 16)) 109 goto errout; 110 111 /* Get current stack pointer for next loop iteration. */ 112 113 sp = regs->areg[base * 4 + 1]; 114 base += inc; 115 } 116 117 regs->wmask = 1; 118 regs->windowstart = 1 << wb; 119 120 return 0; 121 122 errout: 123 return err; 124 } 125 126 /* 127 * Note: We don't copy double exception 'regs', we have to finish double exc. 128 * first before we return to signal handler! This dbl.exc.handler might cause 129 * another double exception, but I think we are fine as the situation is the 130 * same as if we had returned to the signal handerl and got an interrupt 131 * immediately... 132 */ 133 134 static int 135 setup_sigcontext(struct rt_sigframe __user *frame, struct pt_regs *regs) 136 { 137 struct sigcontext __user *sc = &frame->uc.uc_mcontext; 138 struct thread_info *ti = current_thread_info(); 139 int err = 0; 140 141 #define COPY(x) err |= __put_user(regs->x, &sc->sc_##x) 142 COPY(pc); 143 COPY(ps); 144 COPY(lbeg); 145 COPY(lend); 146 COPY(lcount); 147 COPY(sar); 148 #undef COPY 149 150 err |= flush_window_regs_user(regs); 151 err |= __copy_to_user (sc->sc_a, regs->areg, 16 * 4); 152 err |= __put_user(0, &sc->sc_xtregs); 153 154 if (err) 155 return err; 156 157 #if XTENSA_HAVE_COPROCESSORS 158 coprocessor_flush_all(ti); 159 coprocessor_release_all(ti); 160 err |= __copy_to_user(&frame->xtregs.cp, &ti->xtregs_cp, 161 sizeof (frame->xtregs.cp)); 162 #endif 163 err |= __copy_to_user(&frame->xtregs.opt, ®s->xtregs_opt, 164 sizeof (xtregs_opt_t)); 165 err |= __copy_to_user(&frame->xtregs.user, &ti->xtregs_user, 166 sizeof (xtregs_user_t)); 167 168 err |= __put_user(err ? NULL : &frame->xtregs, &sc->sc_xtregs); 169 170 return err; 171 } 172 173 static int 174 restore_sigcontext(struct pt_regs *regs, struct rt_sigframe __user *frame) 175 { 176 struct sigcontext __user *sc = &frame->uc.uc_mcontext; 177 struct thread_info *ti = current_thread_info(); 178 unsigned int err = 0; 179 unsigned long ps; 180 181 #define COPY(x) err |= __get_user(regs->x, &sc->sc_##x) 182 COPY(pc); 183 COPY(lbeg); 184 COPY(lend); 185 COPY(lcount); 186 COPY(sar); 187 #undef COPY 188 189 /* All registers were flushed to stack. Start with a prestine frame. */ 190 191 regs->wmask = 1; 192 regs->windowbase = 0; 193 regs->windowstart = 1; 194 195 regs->syscall = -1; /* disable syscall checks */ 196 197 /* For PS, restore only PS.CALLINC. 198 * Assume that all other bits are either the same as for the signal 199 * handler, or the user mode value doesn't matter (e.g. PS.OWB). 200 */ 201 err |= __get_user(ps, &sc->sc_ps); 202 regs->ps = (regs->ps & ~PS_CALLINC_MASK) | (ps & PS_CALLINC_MASK); 203 204 /* Additional corruption checks */ 205 206 if ((regs->lcount > 0) 207 && ((regs->lbeg > TASK_SIZE) || (regs->lend > TASK_SIZE)) ) 208 err = 1; 209 210 err |= __copy_from_user(regs->areg, sc->sc_a, 16 * 4); 211 212 if (err) 213 return err; 214 215 /* The signal handler may have used coprocessors in which 216 * case they are still enabled. We disable them to force a 217 * reloading of the original task's CP state by the lazy 218 * context-switching mechanisms of CP exception handling. 219 * Also, we essentially discard any coprocessor state that the 220 * signal handler created. */ 221 222 #if XTENSA_HAVE_COPROCESSORS 223 coprocessor_release_all(ti); 224 err |= __copy_from_user(&ti->xtregs_cp, &frame->xtregs.cp, 225 sizeof (frame->xtregs.cp)); 226 #endif 227 err |= __copy_from_user(&ti->xtregs_user, &frame->xtregs.user, 228 sizeof (xtregs_user_t)); 229 err |= __copy_from_user(®s->xtregs_opt, &frame->xtregs.opt, 230 sizeof (xtregs_opt_t)); 231 232 return err; 233 } 234 235 236 /* 237 * Do a signal return; undo the signal stack. 238 */ 239 240 asmlinkage long xtensa_rt_sigreturn(long a0, long a1, long a2, long a3, 241 long a4, long a5, struct pt_regs *regs) 242 { 243 struct rt_sigframe __user *frame; 244 sigset_t set; 245 int ret; 246 247 /* Always make any pending restarted system calls return -EINTR */ 248 current->restart_block.fn = do_no_restart_syscall; 249 250 if (regs->depc > 64) 251 panic("rt_sigreturn in double exception!\n"); 252 253 frame = (struct rt_sigframe __user *) regs->areg[1]; 254 255 if (!access_ok(VERIFY_READ, frame, sizeof(*frame))) 256 goto badframe; 257 258 if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set))) 259 goto badframe; 260 261 set_current_blocked(&set); 262 263 if (restore_sigcontext(regs, frame)) 264 goto badframe; 265 266 ret = regs->areg[2]; 267 268 if (restore_altstack(&frame->uc.uc_stack)) 269 goto badframe; 270 271 return ret; 272 273 badframe: 274 force_sig(SIGSEGV, current); 275 return 0; 276 } 277 278 279 280 /* 281 * Set up a signal frame. 282 */ 283 284 static int 285 gen_return_code(unsigned char *codemem) 286 { 287 int err = 0; 288 289 /* 290 * The 12-bit immediate is really split up within the 24-bit MOVI 291 * instruction. As long as the above system call numbers fit within 292 * 8-bits, the following code works fine. See the Xtensa ISA for 293 * details. 294 */ 295 296 #if __NR_rt_sigreturn > 255 297 # error Generating the MOVI instruction below breaks! 298 #endif 299 300 #ifdef __XTENSA_EB__ /* Big Endian version */ 301 /* Generate instruction: MOVI a2, __NR_rt_sigreturn */ 302 err |= __put_user(0x22, &codemem[0]); 303 err |= __put_user(0x0a, &codemem[1]); 304 err |= __put_user(__NR_rt_sigreturn, &codemem[2]); 305 /* Generate instruction: SYSCALL */ 306 err |= __put_user(0x00, &codemem[3]); 307 err |= __put_user(0x05, &codemem[4]); 308 err |= __put_user(0x00, &codemem[5]); 309 310 #elif defined __XTENSA_EL__ /* Little Endian version */ 311 /* Generate instruction: MOVI a2, __NR_rt_sigreturn */ 312 err |= __put_user(0x22, &codemem[0]); 313 err |= __put_user(0xa0, &codemem[1]); 314 err |= __put_user(__NR_rt_sigreturn, &codemem[2]); 315 /* Generate instruction: SYSCALL */ 316 err |= __put_user(0x00, &codemem[3]); 317 err |= __put_user(0x50, &codemem[4]); 318 err |= __put_user(0x00, &codemem[5]); 319 #else 320 # error Must use compiler for Xtensa processors. 321 #endif 322 323 /* Flush generated code out of the data cache */ 324 325 if (err == 0) { 326 __invalidate_icache_range((unsigned long)codemem, 6UL); 327 __flush_invalidate_dcache_range((unsigned long)codemem, 6UL); 328 } 329 330 return err; 331 } 332 333 334 static int setup_frame(struct ksignal *ksig, sigset_t *set, 335 struct pt_regs *regs) 336 { 337 struct rt_sigframe *frame; 338 int err = 0, sig = ksig->sig; 339 unsigned long sp, ra, tp; 340 341 sp = regs->areg[1]; 342 343 if ((ksig->ka.sa.sa_flags & SA_ONSTACK) != 0 && sas_ss_flags(sp) == 0) { 344 sp = current->sas_ss_sp + current->sas_ss_size; 345 } 346 347 frame = (void *)((sp - sizeof(*frame)) & -16ul); 348 349 if (regs->depc > 64) 350 panic ("Double exception sys_sigreturn\n"); 351 352 if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame))) { 353 return -EFAULT; 354 } 355 356 if (ksig->ka.sa.sa_flags & SA_SIGINFO) { 357 err |= copy_siginfo_to_user(&frame->info, &ksig->info); 358 } 359 360 /* Create the user context. */ 361 362 err |= __put_user(0, &frame->uc.uc_flags); 363 err |= __put_user(0, &frame->uc.uc_link); 364 err |= __save_altstack(&frame->uc.uc_stack, regs->areg[1]); 365 err |= setup_sigcontext(frame, regs); 366 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)); 367 368 if (ksig->ka.sa.sa_flags & SA_RESTORER) { 369 ra = (unsigned long)ksig->ka.sa.sa_restorer; 370 } else { 371 372 /* Create sys_rt_sigreturn syscall in stack frame */ 373 374 err |= gen_return_code(frame->retcode); 375 376 if (err) { 377 return -EFAULT; 378 } 379 ra = (unsigned long) frame->retcode; 380 } 381 382 /* 383 * Create signal handler execution context. 384 * Return context not modified until this point. 385 */ 386 387 /* Set up registers for signal handler; preserve the threadptr */ 388 tp = regs->threadptr; 389 start_thread(regs, (unsigned long) ksig->ka.sa.sa_handler, 390 (unsigned long) frame); 391 392 /* Set up a stack frame for a call4 393 * Note: PS.CALLINC is set to one by start_thread 394 */ 395 regs->areg[4] = (((unsigned long) ra) & 0x3fffffff) | 0x40000000; 396 regs->areg[6] = (unsigned long) sig; 397 regs->areg[7] = (unsigned long) &frame->info; 398 regs->areg[8] = (unsigned long) &frame->uc; 399 regs->threadptr = tp; 400 401 #if DEBUG_SIG 402 printk("SIG rt deliver (%s:%d): signal=%d sp=%p pc=%08x\n", 403 current->comm, current->pid, sig, frame, regs->pc); 404 #endif 405 406 return 0; 407 } 408 409 /* 410 * Note that 'init' is a special process: it doesn't get signals it doesn't 411 * want to handle. Thus you cannot kill init even with a SIGKILL even by 412 * mistake. 413 * 414 * Note that we go through the signals twice: once to check the signals that 415 * the kernel can handle, and then we build all the user-level signal handling 416 * stack-frames in one go after that. 417 */ 418 static void do_signal(struct pt_regs *regs) 419 { 420 struct ksignal ksig; 421 422 task_pt_regs(current)->icountlevel = 0; 423 424 if (get_signal(&ksig)) { 425 int ret; 426 427 /* Are we from a system call? */ 428 429 if ((signed)regs->syscall >= 0) { 430 431 /* If so, check system call restarting.. */ 432 433 switch (regs->areg[2]) { 434 case -ERESTARTNOHAND: 435 case -ERESTART_RESTARTBLOCK: 436 regs->areg[2] = -EINTR; 437 break; 438 439 case -ERESTARTSYS: 440 if (!(ksig.ka.sa.sa_flags & SA_RESTART)) { 441 regs->areg[2] = -EINTR; 442 break; 443 } 444 /* fallthrough */ 445 case -ERESTARTNOINTR: 446 regs->areg[2] = regs->syscall; 447 regs->pc -= 3; 448 break; 449 450 default: 451 /* nothing to do */ 452 if (regs->areg[2] != 0) 453 break; 454 } 455 } 456 457 /* Whee! Actually deliver the signal. */ 458 /* Set up the stack frame */ 459 ret = setup_frame(&ksig, sigmask_to_save(), regs); 460 signal_setup_done(ret, &ksig, 0); 461 if (current->ptrace & PT_SINGLESTEP) 462 task_pt_regs(current)->icountlevel = 1; 463 464 return; 465 } 466 467 /* Did we come from a system call? */ 468 if ((signed) regs->syscall >= 0) { 469 /* Restart the system call - no handlers present */ 470 switch (regs->areg[2]) { 471 case -ERESTARTNOHAND: 472 case -ERESTARTSYS: 473 case -ERESTARTNOINTR: 474 regs->areg[2] = regs->syscall; 475 regs->pc -= 3; 476 break; 477 case -ERESTART_RESTARTBLOCK: 478 regs->areg[2] = __NR_restart_syscall; 479 regs->pc -= 3; 480 break; 481 } 482 } 483 484 /* If there's no signal to deliver, we just restore the saved mask. */ 485 restore_saved_sigmask(); 486 487 if (current->ptrace & PT_SINGLESTEP) 488 task_pt_regs(current)->icountlevel = 1; 489 return; 490 } 491 492 void do_notify_resume(struct pt_regs *regs) 493 { 494 if (test_thread_flag(TIF_SIGPENDING)) 495 do_signal(regs); 496 497 if (test_and_clear_thread_flag(TIF_NOTIFY_RESUME)) 498 tracehook_notify_resume(regs); 499 } 500