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 /* 49 * Flush register windows stored in pt_regs to stack. 50 * Returns 1 for errors. 51 */ 52 53 int 54 flush_window_regs_user(struct pt_regs *regs) 55 { 56 const unsigned long ws = regs->windowstart; 57 const unsigned long wb = regs->windowbase; 58 unsigned long sp = 0; 59 unsigned long wm; 60 int err = 1; 61 int base; 62 63 /* Return if no other frames. */ 64 65 if (regs->wmask == 1) 66 return 0; 67 68 /* Rotate windowmask and skip empty frames. */ 69 70 wm = (ws >> wb) | (ws << (XCHAL_NUM_AREGS / 4 - wb)); 71 base = (XCHAL_NUM_AREGS / 4) - (regs->wmask >> 4); 72 73 /* For call8 or call12 frames, we need the previous stack pointer. */ 74 75 if ((regs->wmask & 2) == 0) 76 if (__get_user(sp, (int*)(regs->areg[base * 4 + 1] - 12))) 77 goto errout; 78 79 /* Spill frames to stack. */ 80 81 while (base < XCHAL_NUM_AREGS / 4) { 82 83 int m = (wm >> base); 84 int inc = 0; 85 86 /* Save registers a4..a7 (call8) or a4...a11 (call12) */ 87 88 if (m & 2) { /* call4 */ 89 inc = 1; 90 91 } else if (m & 4) { /* call8 */ 92 if (copy_to_user(&SPILL_SLOT_CALL8(sp, 4), 93 ®s->areg[(base + 1) * 4], 16)) 94 goto errout; 95 inc = 2; 96 97 } else if (m & 8) { /* call12 */ 98 if (copy_to_user(&SPILL_SLOT_CALL12(sp, 4), 99 ®s->areg[(base + 1) * 4], 32)) 100 goto errout; 101 inc = 3; 102 } 103 104 /* Save current frame a0..a3 under next SP */ 105 106 sp = regs->areg[((base + inc) * 4 + 1) % XCHAL_NUM_AREGS]; 107 if (copy_to_user(&SPILL_SLOT(sp, 0), ®s->areg[base * 4], 16)) 108 goto errout; 109 110 /* Get current stack pointer for next loop iteration. */ 111 112 sp = regs->areg[base * 4 + 1]; 113 base += inc; 114 } 115 116 regs->wmask = 1; 117 regs->windowstart = 1 << wb; 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 rt_sigframe __user *frame, struct pt_regs *regs) 135 { 136 struct sigcontext __user *sc = &frame->uc.uc_mcontext; 137 struct thread_info *ti = current_thread_info(); 138 int err = 0; 139 140 #define COPY(x) err |= __put_user(regs->x, &sc->sc_##x) 141 COPY(pc); 142 COPY(ps); 143 COPY(lbeg); 144 COPY(lend); 145 COPY(lcount); 146 COPY(sar); 147 #undef COPY 148 149 err |= flush_window_regs_user(regs); 150 err |= __copy_to_user (sc->sc_a, regs->areg, 16 * 4); 151 err |= __put_user(0, &sc->sc_xtregs); 152 153 if (err) 154 return err; 155 156 #if XTENSA_HAVE_COPROCESSORS 157 coprocessor_flush_all(ti); 158 coprocessor_release_all(ti); 159 err |= __copy_to_user(&frame->xtregs.cp, &ti->xtregs_cp, 160 sizeof (frame->xtregs.cp)); 161 #endif 162 err |= __copy_to_user(&frame->xtregs.opt, ®s->xtregs_opt, 163 sizeof (xtregs_opt_t)); 164 err |= __copy_to_user(&frame->xtregs.user, &ti->xtregs_user, 165 sizeof (xtregs_user_t)); 166 167 err |= __put_user(err ? NULL : &frame->xtregs, &sc->sc_xtregs); 168 169 return err; 170 } 171 172 static int 173 restore_sigcontext(struct pt_regs *regs, struct rt_sigframe __user *frame) 174 { 175 struct sigcontext __user *sc = &frame->uc.uc_mcontext; 176 struct thread_info *ti = current_thread_info(); 177 unsigned int err = 0; 178 unsigned long ps; 179 180 #define COPY(x) err |= __get_user(regs->x, &sc->sc_##x) 181 COPY(pc); 182 COPY(lbeg); 183 COPY(lend); 184 COPY(lcount); 185 COPY(sar); 186 #undef COPY 187 188 /* All registers were flushed to stack. Start with a pristine frame. */ 189 190 regs->wmask = 1; 191 regs->windowbase = 0; 192 regs->windowstart = 1; 193 194 regs->syscall = NO_SYSCALL; /* disable syscall checks */ 195 196 /* For PS, restore only PS.CALLINC. 197 * Assume that all other bits are either the same as for the signal 198 * handler, or the user mode value doesn't matter (e.g. PS.OWB). 199 */ 200 err |= __get_user(ps, &sc->sc_ps); 201 regs->ps = (regs->ps & ~PS_CALLINC_MASK) | (ps & PS_CALLINC_MASK); 202 203 /* Additional corruption checks */ 204 205 if ((regs->lcount > 0) 206 && ((regs->lbeg > TASK_SIZE) || (regs->lend > TASK_SIZE)) ) 207 err = 1; 208 209 err |= __copy_from_user(regs->areg, sc->sc_a, 16 * 4); 210 211 if (err) 212 return err; 213 214 /* The signal handler may have used coprocessors in which 215 * case they are still enabled. We disable them to force a 216 * reloading of the original task's CP state by the lazy 217 * context-switching mechanisms of CP exception handling. 218 * Also, we essentially discard any coprocessor state that the 219 * signal handler created. */ 220 221 #if XTENSA_HAVE_COPROCESSORS 222 coprocessor_release_all(ti); 223 err |= __copy_from_user(&ti->xtregs_cp, &frame->xtregs.cp, 224 sizeof (frame->xtregs.cp)); 225 #endif 226 err |= __copy_from_user(&ti->xtregs_user, &frame->xtregs.user, 227 sizeof (xtregs_user_t)); 228 err |= __copy_from_user(®s->xtregs_opt, &frame->xtregs.opt, 229 sizeof (xtregs_opt_t)); 230 231 return err; 232 } 233 234 235 /* 236 * Do a signal return; undo the signal stack. 237 */ 238 239 asmlinkage long xtensa_rt_sigreturn(void) 240 { 241 struct pt_regs *regs = current_pt_regs(); 242 struct rt_sigframe __user *frame; 243 sigset_t set; 244 int ret; 245 246 /* Always make any pending restarted system calls return -EINTR */ 247 current->restart_block.fn = do_no_restart_syscall; 248 249 if (regs->depc > 64) 250 panic("rt_sigreturn in double exception!\n"); 251 252 frame = (struct rt_sigframe __user *) regs->areg[1]; 253 254 if (!access_ok(frame, sizeof(*frame))) 255 goto badframe; 256 257 if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set))) 258 goto badframe; 259 260 set_current_blocked(&set); 261 262 if (restore_sigcontext(regs, frame)) 263 goto badframe; 264 265 ret = regs->areg[2]; 266 267 if (restore_altstack(&frame->uc.uc_stack)) 268 goto badframe; 269 270 return ret; 271 272 badframe: 273 force_sig(SIGSEGV); 274 return 0; 275 } 276 277 278 279 /* 280 * Set up a signal frame. 281 */ 282 283 static int 284 gen_return_code(unsigned char *codemem) 285 { 286 int err = 0; 287 288 /* 289 * The 12-bit immediate is really split up within the 24-bit MOVI 290 * instruction. As long as the above system call numbers fit within 291 * 8-bits, the following code works fine. See the Xtensa ISA for 292 * details. 293 */ 294 295 #if __NR_rt_sigreturn > 255 296 # error Generating the MOVI instruction below breaks! 297 #endif 298 299 #ifdef __XTENSA_EB__ /* Big Endian version */ 300 /* Generate instruction: MOVI a2, __NR_rt_sigreturn */ 301 err |= __put_user(0x22, &codemem[0]); 302 err |= __put_user(0x0a, &codemem[1]); 303 err |= __put_user(__NR_rt_sigreturn, &codemem[2]); 304 /* Generate instruction: SYSCALL */ 305 err |= __put_user(0x00, &codemem[3]); 306 err |= __put_user(0x05, &codemem[4]); 307 err |= __put_user(0x00, &codemem[5]); 308 309 #elif defined __XTENSA_EL__ /* Little Endian version */ 310 /* Generate instruction: MOVI a2, __NR_rt_sigreturn */ 311 err |= __put_user(0x22, &codemem[0]); 312 err |= __put_user(0xa0, &codemem[1]); 313 err |= __put_user(__NR_rt_sigreturn, &codemem[2]); 314 /* Generate instruction: SYSCALL */ 315 err |= __put_user(0x00, &codemem[3]); 316 err |= __put_user(0x50, &codemem[4]); 317 err |= __put_user(0x00, &codemem[5]); 318 #else 319 # error Must use compiler for Xtensa processors. 320 #endif 321 322 /* Flush generated code out of the data cache */ 323 324 if (err == 0) { 325 __invalidate_icache_range((unsigned long)codemem, 6UL); 326 __flush_invalidate_dcache_range((unsigned long)codemem, 6UL); 327 } 328 329 return err; 330 } 331 332 333 static int setup_frame(struct ksignal *ksig, sigset_t *set, 334 struct pt_regs *regs) 335 { 336 struct rt_sigframe *frame; 337 int err = 0, sig = ksig->sig; 338 unsigned long sp, ra, tp, ps; 339 unsigned int base; 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(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 ps = regs->ps; 390 start_thread(regs, (unsigned long) ksig->ka.sa.sa_handler, 391 (unsigned long) frame); 392 393 /* Set up a stack frame for a call4 if userspace uses windowed ABI */ 394 if (ps & PS_WOE_MASK) { 395 base = 4; 396 regs->areg[base] = 397 (((unsigned long) ra) & 0x3fffffff) | 0x40000000; 398 ps = (ps & ~(PS_CALLINC_MASK | PS_OWB_MASK)) | 399 (1 << PS_CALLINC_SHIFT); 400 } else { 401 base = 0; 402 regs->areg[base] = (unsigned long) ra; 403 } 404 regs->areg[base + 2] = (unsigned long) sig; 405 regs->areg[base + 3] = (unsigned long) &frame->info; 406 regs->areg[base + 4] = (unsigned long) &frame->uc; 407 regs->threadptr = tp; 408 regs->ps = ps; 409 410 pr_debug("SIG rt deliver (%s:%d): signal=%d sp=%p pc=%08lx\n", 411 current->comm, current->pid, sig, frame, regs->pc); 412 413 return 0; 414 } 415 416 /* 417 * Note that 'init' is a special process: it doesn't get signals it doesn't 418 * want to handle. Thus you cannot kill init even with a SIGKILL even by 419 * mistake. 420 * 421 * Note that we go through the signals twice: once to check the signals that 422 * the kernel can handle, and then we build all the user-level signal handling 423 * stack-frames in one go after that. 424 */ 425 static void do_signal(struct pt_regs *regs) 426 { 427 struct ksignal ksig; 428 429 task_pt_regs(current)->icountlevel = 0; 430 431 if (get_signal(&ksig)) { 432 int ret; 433 434 /* Are we from a system call? */ 435 436 if (regs->syscall != NO_SYSCALL) { 437 438 /* If so, check system call restarting.. */ 439 440 switch (regs->areg[2]) { 441 case -ERESTARTNOHAND: 442 case -ERESTART_RESTARTBLOCK: 443 regs->areg[2] = -EINTR; 444 break; 445 446 case -ERESTARTSYS: 447 if (!(ksig.ka.sa.sa_flags & SA_RESTART)) { 448 regs->areg[2] = -EINTR; 449 break; 450 } 451 fallthrough; 452 case -ERESTARTNOINTR: 453 regs->areg[2] = regs->syscall; 454 regs->pc -= 3; 455 break; 456 457 default: 458 /* nothing to do */ 459 if (regs->areg[2] != 0) 460 break; 461 } 462 } 463 464 /* Whee! Actually deliver the signal. */ 465 /* Set up the stack frame */ 466 ret = setup_frame(&ksig, sigmask_to_save(), regs); 467 signal_setup_done(ret, &ksig, 0); 468 if (current->ptrace & PT_SINGLESTEP) 469 task_pt_regs(current)->icountlevel = 1; 470 471 return; 472 } 473 474 /* Did we come from a system call? */ 475 if (regs->syscall != NO_SYSCALL) { 476 /* Restart the system call - no handlers present */ 477 switch (regs->areg[2]) { 478 case -ERESTARTNOHAND: 479 case -ERESTARTSYS: 480 case -ERESTARTNOINTR: 481 regs->areg[2] = regs->syscall; 482 regs->pc -= 3; 483 break; 484 case -ERESTART_RESTARTBLOCK: 485 regs->areg[2] = __NR_restart_syscall; 486 regs->pc -= 3; 487 break; 488 } 489 } 490 491 /* If there's no signal to deliver, we just restore the saved mask. */ 492 restore_saved_sigmask(); 493 494 if (current->ptrace & PT_SINGLESTEP) 495 task_pt_regs(current)->icountlevel = 1; 496 return; 497 } 498 499 void do_notify_resume(struct pt_regs *regs) 500 { 501 if (test_thread_flag(TIF_SIGPENDING)) 502 do_signal(regs); 503 504 if (test_thread_flag(TIF_NOTIFY_RESUME)) 505 tracehook_notify_resume(regs); 506 } 507