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 #include <linux/sched/task_stack.h> 24 25 #include <asm/ucontext.h> 26 #include <linux/uaccess.h> 27 #include <asm/cacheflush.h> 28 #include <asm/coprocessor.h> 29 #include <asm/unistd.h> 30 31 extern struct task_struct *coproc_owners[]; 32 33 struct rt_sigframe 34 { 35 struct siginfo info; 36 struct ucontext uc; 37 struct { 38 xtregs_opt_t opt; 39 xtregs_user_t user; 40 #if XTENSA_HAVE_COPROCESSORS 41 xtregs_coprocessor_t cp; 42 #endif 43 } xtregs; 44 unsigned char retcode[6]; 45 unsigned int window[4]; 46 }; 47 48 #if defined(USER_SUPPORT_WINDOWED) 49 /* 50 * Flush register windows stored in pt_regs to stack. 51 * Returns 1 for errors. 52 */ 53 54 static 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(&SPILL_SLOT_CALL8(sp, 4), 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(&SPILL_SLOT_CALL12(sp, 4), 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(&SPILL_SLOT(sp, 0), ®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 #else 126 static int 127 flush_window_regs_user(struct pt_regs *regs) 128 { 129 return 0; 130 } 131 #endif 132 133 /* 134 * Note: We don't copy double exception 'regs', we have to finish double exc. 135 * first before we return to signal handler! This dbl.exc.handler might cause 136 * another double exception, but I think we are fine as the situation is the 137 * same as if we had returned to the signal handerl and got an interrupt 138 * immediately... 139 */ 140 141 static int 142 setup_sigcontext(struct rt_sigframe __user *frame, struct pt_regs *regs) 143 { 144 struct sigcontext __user *sc = &frame->uc.uc_mcontext; 145 struct thread_info *ti = current_thread_info(); 146 int err = 0; 147 148 #define COPY(x) err |= __put_user(regs->x, &sc->sc_##x) 149 COPY(pc); 150 COPY(ps); 151 COPY(lbeg); 152 COPY(lend); 153 COPY(lcount); 154 COPY(sar); 155 #undef COPY 156 157 err |= flush_window_regs_user(regs); 158 err |= __copy_to_user (sc->sc_a, regs->areg, 16 * 4); 159 err |= __put_user(0, &sc->sc_xtregs); 160 161 if (err) 162 return err; 163 164 #if XTENSA_HAVE_COPROCESSORS 165 coprocessor_flush_all(ti); 166 coprocessor_release_all(ti); 167 err |= __copy_to_user(&frame->xtregs.cp, &ti->xtregs_cp, 168 sizeof (frame->xtregs.cp)); 169 #endif 170 err |= __copy_to_user(&frame->xtregs.opt, ®s->xtregs_opt, 171 sizeof (xtregs_opt_t)); 172 err |= __copy_to_user(&frame->xtregs.user, &ti->xtregs_user, 173 sizeof (xtregs_user_t)); 174 175 err |= __put_user(err ? NULL : &frame->xtregs, &sc->sc_xtregs); 176 177 return err; 178 } 179 180 static int 181 restore_sigcontext(struct pt_regs *regs, struct rt_sigframe __user *frame) 182 { 183 struct sigcontext __user *sc = &frame->uc.uc_mcontext; 184 struct thread_info *ti = current_thread_info(); 185 unsigned int err = 0; 186 unsigned long ps; 187 188 #define COPY(x) err |= __get_user(regs->x, &sc->sc_##x) 189 COPY(pc); 190 COPY(lbeg); 191 COPY(lend); 192 COPY(lcount); 193 COPY(sar); 194 #undef COPY 195 196 /* All registers were flushed to stack. Start with a pristine frame. */ 197 198 regs->wmask = 1; 199 regs->windowbase = 0; 200 regs->windowstart = 1; 201 202 regs->syscall = NO_SYSCALL; /* disable syscall checks */ 203 204 /* For PS, restore only PS.CALLINC. 205 * Assume that all other bits are either the same as for the signal 206 * handler, or the user mode value doesn't matter (e.g. PS.OWB). 207 */ 208 err |= __get_user(ps, &sc->sc_ps); 209 regs->ps = (regs->ps & ~PS_CALLINC_MASK) | (ps & PS_CALLINC_MASK); 210 211 /* Additional corruption checks */ 212 213 if ((regs->lcount > 0) 214 && ((regs->lbeg > TASK_SIZE) || (regs->lend > TASK_SIZE)) ) 215 err = 1; 216 217 err |= __copy_from_user(regs->areg, sc->sc_a, 16 * 4); 218 219 if (err) 220 return err; 221 222 /* The signal handler may have used coprocessors in which 223 * case they are still enabled. We disable them to force a 224 * reloading of the original task's CP state by the lazy 225 * context-switching mechanisms of CP exception handling. 226 * Also, we essentially discard any coprocessor state that the 227 * signal handler created. */ 228 229 #if XTENSA_HAVE_COPROCESSORS 230 coprocessor_release_all(ti); 231 err |= __copy_from_user(&ti->xtregs_cp, &frame->xtregs.cp, 232 sizeof (frame->xtregs.cp)); 233 #endif 234 err |= __copy_from_user(&ti->xtregs_user, &frame->xtregs.user, 235 sizeof (xtregs_user_t)); 236 err |= __copy_from_user(®s->xtregs_opt, &frame->xtregs.opt, 237 sizeof (xtregs_opt_t)); 238 239 return err; 240 } 241 242 243 /* 244 * Do a signal return; undo the signal stack. 245 */ 246 247 asmlinkage long xtensa_rt_sigreturn(void) 248 { 249 struct pt_regs *regs = current_pt_regs(); 250 struct rt_sigframe __user *frame; 251 sigset_t set; 252 int ret; 253 254 /* Always make any pending restarted system calls return -EINTR */ 255 current->restart_block.fn = do_no_restart_syscall; 256 257 if (regs->depc > 64) 258 panic("rt_sigreturn in double exception!\n"); 259 260 frame = (struct rt_sigframe __user *) regs->areg[1]; 261 262 if (!access_ok(frame, sizeof(*frame))) 263 goto badframe; 264 265 if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set))) 266 goto badframe; 267 268 set_current_blocked(&set); 269 270 if (restore_sigcontext(regs, frame)) 271 goto badframe; 272 273 ret = regs->areg[2]; 274 275 if (restore_altstack(&frame->uc.uc_stack)) 276 goto badframe; 277 278 return ret; 279 280 badframe: 281 force_sig(SIGSEGV); 282 return 0; 283 } 284 285 286 287 /* 288 * Set up a signal frame. 289 */ 290 291 static int 292 gen_return_code(unsigned char *codemem) 293 { 294 int err = 0; 295 296 /* 297 * The 12-bit immediate is really split up within the 24-bit MOVI 298 * instruction. As long as the above system call numbers fit within 299 * 8-bits, the following code works fine. See the Xtensa ISA for 300 * details. 301 */ 302 303 #if __NR_rt_sigreturn > 255 304 # error Generating the MOVI instruction below breaks! 305 #endif 306 307 #ifdef __XTENSA_EB__ /* Big Endian version */ 308 /* Generate instruction: MOVI a2, __NR_rt_sigreturn */ 309 err |= __put_user(0x22, &codemem[0]); 310 err |= __put_user(0x0a, &codemem[1]); 311 err |= __put_user(__NR_rt_sigreturn, &codemem[2]); 312 /* Generate instruction: SYSCALL */ 313 err |= __put_user(0x00, &codemem[3]); 314 err |= __put_user(0x05, &codemem[4]); 315 err |= __put_user(0x00, &codemem[5]); 316 317 #elif defined __XTENSA_EL__ /* Little Endian version */ 318 /* Generate instruction: MOVI a2, __NR_rt_sigreturn */ 319 err |= __put_user(0x22, &codemem[0]); 320 err |= __put_user(0xa0, &codemem[1]); 321 err |= __put_user(__NR_rt_sigreturn, &codemem[2]); 322 /* Generate instruction: SYSCALL */ 323 err |= __put_user(0x00, &codemem[3]); 324 err |= __put_user(0x50, &codemem[4]); 325 err |= __put_user(0x00, &codemem[5]); 326 #else 327 # error Must use compiler for Xtensa processors. 328 #endif 329 330 /* Flush generated code out of the data cache */ 331 332 if (err == 0) { 333 __invalidate_icache_range((unsigned long)codemem, 6UL); 334 __flush_invalidate_dcache_range((unsigned long)codemem, 6UL); 335 } 336 337 return err; 338 } 339 340 341 static int setup_frame(struct ksignal *ksig, sigset_t *set, 342 struct pt_regs *regs) 343 { 344 struct rt_sigframe *frame; 345 int err = 0, sig = ksig->sig; 346 unsigned long sp, ra, tp, ps; 347 unsigned int base; 348 349 sp = regs->areg[1]; 350 351 if ((ksig->ka.sa.sa_flags & SA_ONSTACK) != 0 && sas_ss_flags(sp) == 0) { 352 sp = current->sas_ss_sp + current->sas_ss_size; 353 } 354 355 frame = (void *)((sp - sizeof(*frame)) & -16ul); 356 357 if (regs->depc > 64) 358 panic ("Double exception sys_sigreturn\n"); 359 360 if (!access_ok(frame, sizeof(*frame))) { 361 return -EFAULT; 362 } 363 364 if (ksig->ka.sa.sa_flags & SA_SIGINFO) { 365 err |= copy_siginfo_to_user(&frame->info, &ksig->info); 366 } 367 368 /* Create the user context. */ 369 370 err |= __put_user(0, &frame->uc.uc_flags); 371 err |= __put_user(0, &frame->uc.uc_link); 372 err |= __save_altstack(&frame->uc.uc_stack, regs->areg[1]); 373 err |= setup_sigcontext(frame, regs); 374 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)); 375 376 if (ksig->ka.sa.sa_flags & SA_RESTORER) { 377 ra = (unsigned long)ksig->ka.sa.sa_restorer; 378 } else { 379 380 /* Create sys_rt_sigreturn syscall in stack frame */ 381 382 err |= gen_return_code(frame->retcode); 383 384 if (err) { 385 return -EFAULT; 386 } 387 ra = (unsigned long) frame->retcode; 388 } 389 390 /* 391 * Create signal handler execution context. 392 * Return context not modified until this point. 393 */ 394 395 /* Set up registers for signal handler; preserve the threadptr */ 396 tp = regs->threadptr; 397 ps = regs->ps; 398 start_thread(regs, (unsigned long) ksig->ka.sa.sa_handler, 399 (unsigned long) frame); 400 401 /* Set up a stack frame for a call4 if userspace uses windowed ABI */ 402 if (ps & PS_WOE_MASK) { 403 base = 4; 404 regs->areg[base] = 405 (((unsigned long) ra) & 0x3fffffff) | 0x40000000; 406 ps = (ps & ~(PS_CALLINC_MASK | PS_OWB_MASK)) | 407 (1 << PS_CALLINC_SHIFT); 408 } else { 409 base = 0; 410 regs->areg[base] = (unsigned long) ra; 411 } 412 regs->areg[base + 2] = (unsigned long) sig; 413 regs->areg[base + 3] = (unsigned long) &frame->info; 414 regs->areg[base + 4] = (unsigned long) &frame->uc; 415 regs->threadptr = tp; 416 regs->ps = ps; 417 418 pr_debug("SIG rt deliver (%s:%d): signal=%d sp=%p pc=%08lx\n", 419 current->comm, current->pid, sig, frame, regs->pc); 420 421 return 0; 422 } 423 424 /* 425 * Note that 'init' is a special process: it doesn't get signals it doesn't 426 * want to handle. Thus you cannot kill init even with a SIGKILL even by 427 * mistake. 428 * 429 * Note that we go through the signals twice: once to check the signals that 430 * the kernel can handle, and then we build all the user-level signal handling 431 * stack-frames in one go after that. 432 */ 433 static void do_signal(struct pt_regs *regs) 434 { 435 struct ksignal ksig; 436 437 task_pt_regs(current)->icountlevel = 0; 438 439 if (get_signal(&ksig)) { 440 int ret; 441 442 /* Are we from a system call? */ 443 444 if (regs->syscall != NO_SYSCALL) { 445 446 /* If so, check system call restarting.. */ 447 448 switch (regs->areg[2]) { 449 case -ERESTARTNOHAND: 450 case -ERESTART_RESTARTBLOCK: 451 regs->areg[2] = -EINTR; 452 break; 453 454 case -ERESTARTSYS: 455 if (!(ksig.ka.sa.sa_flags & SA_RESTART)) { 456 regs->areg[2] = -EINTR; 457 break; 458 } 459 fallthrough; 460 case -ERESTARTNOINTR: 461 regs->areg[2] = regs->syscall; 462 regs->pc -= 3; 463 break; 464 465 default: 466 /* nothing to do */ 467 if (regs->areg[2] != 0) 468 break; 469 } 470 } 471 472 /* Whee! Actually deliver the signal. */ 473 /* Set up the stack frame */ 474 ret = setup_frame(&ksig, sigmask_to_save(), regs); 475 signal_setup_done(ret, &ksig, 0); 476 if (current->ptrace & PT_SINGLESTEP) 477 task_pt_regs(current)->icountlevel = 1; 478 479 return; 480 } 481 482 /* Did we come from a system call? */ 483 if (regs->syscall != NO_SYSCALL) { 484 /* Restart the system call - no handlers present */ 485 switch (regs->areg[2]) { 486 case -ERESTARTNOHAND: 487 case -ERESTARTSYS: 488 case -ERESTARTNOINTR: 489 regs->areg[2] = regs->syscall; 490 regs->pc -= 3; 491 break; 492 case -ERESTART_RESTARTBLOCK: 493 regs->areg[2] = __NR_restart_syscall; 494 regs->pc -= 3; 495 break; 496 } 497 } 498 499 /* If there's no signal to deliver, we just restore the saved mask. */ 500 restore_saved_sigmask(); 501 502 if (current->ptrace & PT_SINGLESTEP) 503 task_pt_regs(current)->icountlevel = 1; 504 return; 505 } 506 507 void do_notify_resume(struct pt_regs *regs) 508 { 509 if (test_thread_flag(TIF_SIGPENDING) || 510 test_thread_flag(TIF_NOTIFY_SIGNAL)) 511 do_signal(regs); 512 513 if (test_thread_flag(TIF_NOTIFY_RESUME)) 514 tracehook_notify_resume(regs); 515 } 516