1 // SPDX-License-Identifier: GPL-2.0 2 /* linux/arch/sparc/kernel/signal.c 3 * 4 * Copyright (C) 1991, 1992 Linus Torvalds 5 * Copyright (C) 1995 David S. Miller (davem@caip.rutgers.edu) 6 * Copyright (C) 1996 Miguel de Icaza (miguel@nuclecu.unam.mx) 7 * Copyright (C) 1997 Eddie C. Dost (ecd@skynet.be) 8 */ 9 10 #include <linux/sched.h> 11 #include <linux/kernel.h> 12 #include <linux/signal.h> 13 #include <linux/errno.h> 14 #include <linux/wait.h> 15 #include <linux/ptrace.h> 16 #include <linux/unistd.h> 17 #include <linux/mm.h> 18 #include <linux/tty.h> 19 #include <linux/smp.h> 20 #include <linux/binfmts.h> /* do_coredum */ 21 #include <linux/bitops.h> 22 #include <linux/tracehook.h> 23 24 #include <linux/uaccess.h> 25 #include <asm/ptrace.h> 26 #include <asm/pgalloc.h> 27 #include <asm/cacheflush.h> /* flush_sig_insns */ 28 #include <asm/switch_to.h> 29 30 #include "sigutil.h" 31 #include "kernel.h" 32 33 extern void fpsave(unsigned long *fpregs, unsigned long *fsr, 34 void *fpqueue, unsigned long *fpqdepth); 35 extern void fpload(unsigned long *fpregs, unsigned long *fsr); 36 37 struct signal_frame { 38 struct sparc_stackf ss; 39 __siginfo32_t info; 40 __siginfo_fpu_t __user *fpu_save; 41 unsigned long insns[2] __attribute__ ((aligned (8))); 42 unsigned int extramask[_NSIG_WORDS - 1]; 43 unsigned int extra_size; /* Should be 0 */ 44 __siginfo_rwin_t __user *rwin_save; 45 } __attribute__((aligned(8))); 46 47 struct rt_signal_frame { 48 struct sparc_stackf ss; 49 siginfo_t info; 50 struct pt_regs regs; 51 sigset_t mask; 52 __siginfo_fpu_t __user *fpu_save; 53 unsigned int insns[2]; 54 stack_t stack; 55 unsigned int extra_size; /* Should be 0 */ 56 __siginfo_rwin_t __user *rwin_save; 57 } __attribute__((aligned(8))); 58 59 /* Align macros */ 60 #define SF_ALIGNEDSZ (((sizeof(struct signal_frame) + 7) & (~7))) 61 #define RT_ALIGNEDSZ (((sizeof(struct rt_signal_frame) + 7) & (~7))) 62 63 /* Checks if the fp is valid. We always build signal frames which are 64 * 16-byte aligned, therefore we can always enforce that the restore 65 * frame has that property as well. 66 */ 67 static inline bool invalid_frame_pointer(void __user *fp, int fplen) 68 { 69 if ((((unsigned long) fp) & 15) || !__access_ok((unsigned long)fp, fplen)) 70 return true; 71 72 return false; 73 } 74 75 asmlinkage void do_sigreturn(struct pt_regs *regs) 76 { 77 unsigned long up_psr, pc, npc, ufp; 78 struct signal_frame __user *sf; 79 sigset_t set; 80 __siginfo_fpu_t __user *fpu_save; 81 __siginfo_rwin_t __user *rwin_save; 82 int err; 83 84 /* Always make any pending restarted system calls return -EINTR */ 85 current->restart_block.fn = do_no_restart_syscall; 86 87 synchronize_user_stack(); 88 89 sf = (struct signal_frame __user *) regs->u_regs[UREG_FP]; 90 91 /* 1. Make sure we are not getting garbage from the user */ 92 if (invalid_frame_pointer(sf, sizeof(*sf))) 93 goto segv_and_exit; 94 95 if (get_user(ufp, &sf->info.si_regs.u_regs[UREG_FP])) 96 goto segv_and_exit; 97 98 if (ufp & 0x7) 99 goto segv_and_exit; 100 101 err = __get_user(pc, &sf->info.si_regs.pc); 102 err |= __get_user(npc, &sf->info.si_regs.npc); 103 104 if ((pc | npc) & 3) 105 goto segv_and_exit; 106 107 /* 2. Restore the state */ 108 up_psr = regs->psr; 109 err |= __copy_from_user(regs, &sf->info.si_regs, sizeof(struct pt_regs)); 110 111 /* User can only change condition codes and FPU enabling in %psr. */ 112 regs->psr = (up_psr & ~(PSR_ICC | PSR_EF)) 113 | (regs->psr & (PSR_ICC | PSR_EF)); 114 115 /* Prevent syscall restart. */ 116 pt_regs_clear_syscall(regs); 117 118 err |= __get_user(fpu_save, &sf->fpu_save); 119 if (fpu_save) 120 err |= restore_fpu_state(regs, fpu_save); 121 err |= __get_user(rwin_save, &sf->rwin_save); 122 if (rwin_save) 123 err |= restore_rwin_state(rwin_save); 124 125 /* This is pretty much atomic, no amount locking would prevent 126 * the races which exist anyways. 127 */ 128 err |= __get_user(set.sig[0], &sf->info.si_mask); 129 err |= __copy_from_user(&set.sig[1], &sf->extramask, 130 (_NSIG_WORDS-1) * sizeof(unsigned int)); 131 132 if (err) 133 goto segv_and_exit; 134 135 set_current_blocked(&set); 136 return; 137 138 segv_and_exit: 139 force_sig(SIGSEGV); 140 } 141 142 asmlinkage void do_rt_sigreturn(struct pt_regs *regs) 143 { 144 struct rt_signal_frame __user *sf; 145 unsigned int psr, pc, npc, ufp; 146 __siginfo_fpu_t __user *fpu_save; 147 __siginfo_rwin_t __user *rwin_save; 148 sigset_t set; 149 int err; 150 151 synchronize_user_stack(); 152 sf = (struct rt_signal_frame __user *) regs->u_regs[UREG_FP]; 153 if (invalid_frame_pointer(sf, sizeof(*sf))) 154 goto segv; 155 156 if (get_user(ufp, &sf->regs.u_regs[UREG_FP])) 157 goto segv; 158 159 if (ufp & 0x7) 160 goto segv; 161 162 err = __get_user(pc, &sf->regs.pc); 163 err |= __get_user(npc, &sf->regs.npc); 164 err |= ((pc | npc) & 0x03); 165 166 err |= __get_user(regs->y, &sf->regs.y); 167 err |= __get_user(psr, &sf->regs.psr); 168 169 err |= __copy_from_user(®s->u_regs[UREG_G1], 170 &sf->regs.u_regs[UREG_G1], 15 * sizeof(u32)); 171 172 regs->psr = (regs->psr & ~PSR_ICC) | (psr & PSR_ICC); 173 174 /* Prevent syscall restart. */ 175 pt_regs_clear_syscall(regs); 176 177 err |= __get_user(fpu_save, &sf->fpu_save); 178 if (!err && fpu_save) 179 err |= restore_fpu_state(regs, fpu_save); 180 err |= __copy_from_user(&set, &sf->mask, sizeof(sigset_t)); 181 err |= restore_altstack(&sf->stack); 182 183 if (err) 184 goto segv; 185 186 regs->pc = pc; 187 regs->npc = npc; 188 189 err |= __get_user(rwin_save, &sf->rwin_save); 190 if (!err && rwin_save) { 191 if (restore_rwin_state(rwin_save)) 192 goto segv; 193 } 194 195 set_current_blocked(&set); 196 return; 197 segv: 198 force_sig(SIGSEGV); 199 } 200 201 static inline void __user *get_sigframe(struct ksignal *ksig, struct pt_regs *regs, unsigned long framesize) 202 { 203 unsigned long sp = regs->u_regs[UREG_FP]; 204 205 /* 206 * If we are on the alternate signal stack and would overflow it, don't. 207 * Return an always-bogus address instead so we will die with SIGSEGV. 208 */ 209 if (on_sig_stack(sp) && !likely(on_sig_stack(sp - framesize))) 210 return (void __user *) -1L; 211 212 /* This is the X/Open sanctioned signal stack switching. */ 213 sp = sigsp(sp, ksig) - framesize; 214 215 /* Always align the stack frame. This handles two cases. First, 216 * sigaltstack need not be mindful of platform specific stack 217 * alignment. Second, if we took this signal because the stack 218 * is not aligned properly, we'd like to take the signal cleanly 219 * and report that. 220 */ 221 sp &= ~15UL; 222 223 return (void __user *) sp; 224 } 225 226 static int setup_frame(struct ksignal *ksig, struct pt_regs *regs, 227 sigset_t *oldset) 228 { 229 struct signal_frame __user *sf; 230 int sigframe_size, err, wsaved; 231 void __user *tail; 232 233 /* 1. Make sure everything is clean */ 234 synchronize_user_stack(); 235 236 wsaved = current_thread_info()->w_saved; 237 238 sigframe_size = sizeof(*sf); 239 if (used_math()) 240 sigframe_size += sizeof(__siginfo_fpu_t); 241 if (wsaved) 242 sigframe_size += sizeof(__siginfo_rwin_t); 243 244 sf = (struct signal_frame __user *) 245 get_sigframe(ksig, regs, sigframe_size); 246 247 if (invalid_frame_pointer(sf, sigframe_size)) { 248 do_exit(SIGILL); 249 return -EINVAL; 250 } 251 252 tail = sf + 1; 253 254 /* 2. Save the current process state */ 255 err = __copy_to_user(&sf->info.si_regs, regs, sizeof(struct pt_regs)); 256 257 err |= __put_user(0, &sf->extra_size); 258 259 if (used_math()) { 260 __siginfo_fpu_t __user *fp = tail; 261 tail += sizeof(*fp); 262 err |= save_fpu_state(regs, fp); 263 err |= __put_user(fp, &sf->fpu_save); 264 } else { 265 err |= __put_user(0, &sf->fpu_save); 266 } 267 if (wsaved) { 268 __siginfo_rwin_t __user *rwp = tail; 269 tail += sizeof(*rwp); 270 err |= save_rwin_state(wsaved, rwp); 271 err |= __put_user(rwp, &sf->rwin_save); 272 } else { 273 err |= __put_user(0, &sf->rwin_save); 274 } 275 276 err |= __put_user(oldset->sig[0], &sf->info.si_mask); 277 err |= __copy_to_user(sf->extramask, &oldset->sig[1], 278 (_NSIG_WORDS - 1) * sizeof(unsigned int)); 279 if (!wsaved) { 280 err |= __copy_to_user(sf, (char *) regs->u_regs[UREG_FP], 281 sizeof(struct reg_window32)); 282 } else { 283 struct reg_window32 *rp; 284 285 rp = ¤t_thread_info()->reg_window[wsaved - 1]; 286 err |= __copy_to_user(sf, rp, sizeof(struct reg_window32)); 287 } 288 if (err) 289 return err; 290 291 /* 3. signal handler back-trampoline and parameters */ 292 regs->u_regs[UREG_FP] = (unsigned long) sf; 293 regs->u_regs[UREG_I0] = ksig->sig; 294 regs->u_regs[UREG_I1] = (unsigned long) &sf->info; 295 regs->u_regs[UREG_I2] = (unsigned long) &sf->info; 296 297 /* 4. signal handler */ 298 regs->pc = (unsigned long) ksig->ka.sa.sa_handler; 299 regs->npc = (regs->pc + 4); 300 301 /* 5. return to kernel instructions */ 302 if (ksig->ka.ka_restorer) 303 regs->u_regs[UREG_I7] = (unsigned long)ksig->ka.ka_restorer; 304 else { 305 regs->u_regs[UREG_I7] = (unsigned long)(&(sf->insns[0]) - 2); 306 307 /* mov __NR_sigreturn, %g1 */ 308 err |= __put_user(0x821020d8, &sf->insns[0]); 309 310 /* t 0x10 */ 311 err |= __put_user(0x91d02010, &sf->insns[1]); 312 if (err) 313 return err; 314 315 /* Flush instruction space. */ 316 flush_sig_insns(current->mm, (unsigned long) &(sf->insns[0])); 317 } 318 return 0; 319 } 320 321 static int setup_rt_frame(struct ksignal *ksig, struct pt_regs *regs, 322 sigset_t *oldset) 323 { 324 struct rt_signal_frame __user *sf; 325 int sigframe_size, wsaved; 326 void __user *tail; 327 unsigned int psr; 328 int err; 329 330 synchronize_user_stack(); 331 wsaved = current_thread_info()->w_saved; 332 sigframe_size = sizeof(*sf); 333 if (used_math()) 334 sigframe_size += sizeof(__siginfo_fpu_t); 335 if (wsaved) 336 sigframe_size += sizeof(__siginfo_rwin_t); 337 sf = (struct rt_signal_frame __user *) 338 get_sigframe(ksig, regs, sigframe_size); 339 if (invalid_frame_pointer(sf, sigframe_size)) { 340 do_exit(SIGILL); 341 return -EINVAL; 342 } 343 344 tail = sf + 1; 345 err = __put_user(regs->pc, &sf->regs.pc); 346 err |= __put_user(regs->npc, &sf->regs.npc); 347 err |= __put_user(regs->y, &sf->regs.y); 348 psr = regs->psr; 349 if (used_math()) 350 psr |= PSR_EF; 351 err |= __put_user(psr, &sf->regs.psr); 352 err |= __copy_to_user(&sf->regs.u_regs, regs->u_regs, sizeof(regs->u_regs)); 353 err |= __put_user(0, &sf->extra_size); 354 355 if (psr & PSR_EF) { 356 __siginfo_fpu_t __user *fp = tail; 357 tail += sizeof(*fp); 358 err |= save_fpu_state(regs, fp); 359 err |= __put_user(fp, &sf->fpu_save); 360 } else { 361 err |= __put_user(0, &sf->fpu_save); 362 } 363 if (wsaved) { 364 __siginfo_rwin_t __user *rwp = tail; 365 tail += sizeof(*rwp); 366 err |= save_rwin_state(wsaved, rwp); 367 err |= __put_user(rwp, &sf->rwin_save); 368 } else { 369 err |= __put_user(0, &sf->rwin_save); 370 } 371 err |= __copy_to_user(&sf->mask, &oldset->sig[0], sizeof(sigset_t)); 372 373 /* Setup sigaltstack */ 374 err |= __save_altstack(&sf->stack, regs->u_regs[UREG_FP]); 375 376 if (!wsaved) { 377 err |= __copy_to_user(sf, (char *) regs->u_regs[UREG_FP], 378 sizeof(struct reg_window32)); 379 } else { 380 struct reg_window32 *rp; 381 382 rp = ¤t_thread_info()->reg_window[wsaved - 1]; 383 err |= __copy_to_user(sf, rp, sizeof(struct reg_window32)); 384 } 385 386 err |= copy_siginfo_to_user(&sf->info, &ksig->info); 387 388 if (err) 389 return err; 390 391 regs->u_regs[UREG_FP] = (unsigned long) sf; 392 regs->u_regs[UREG_I0] = ksig->sig; 393 regs->u_regs[UREG_I1] = (unsigned long) &sf->info; 394 regs->u_regs[UREG_I2] = (unsigned long) &sf->regs; 395 396 regs->pc = (unsigned long) ksig->ka.sa.sa_handler; 397 regs->npc = (regs->pc + 4); 398 399 if (ksig->ka.ka_restorer) 400 regs->u_regs[UREG_I7] = (unsigned long)ksig->ka.ka_restorer; 401 else { 402 regs->u_regs[UREG_I7] = (unsigned long)(&(sf->insns[0]) - 2); 403 404 /* mov __NR_sigreturn, %g1 */ 405 err |= __put_user(0x821020d8, &sf->insns[0]); 406 407 /* t 0x10 */ 408 err |= __put_user(0x91d02010, &sf->insns[1]); 409 if (err) 410 return err; 411 412 /* Flush instruction space. */ 413 flush_sig_insns(current->mm, (unsigned long) &(sf->insns[0])); 414 } 415 return 0; 416 } 417 418 static inline void 419 handle_signal(struct ksignal *ksig, struct pt_regs *regs) 420 { 421 sigset_t *oldset = sigmask_to_save(); 422 int err; 423 424 if (ksig->ka.sa.sa_flags & SA_SIGINFO) 425 err = setup_rt_frame(ksig, regs, oldset); 426 else 427 err = setup_frame(ksig, regs, oldset); 428 signal_setup_done(err, ksig, 0); 429 } 430 431 static inline void syscall_restart(unsigned long orig_i0, struct pt_regs *regs, 432 struct sigaction *sa) 433 { 434 switch(regs->u_regs[UREG_I0]) { 435 case ERESTART_RESTARTBLOCK: 436 case ERESTARTNOHAND: 437 no_system_call_restart: 438 regs->u_regs[UREG_I0] = EINTR; 439 regs->psr |= PSR_C; 440 break; 441 case ERESTARTSYS: 442 if (!(sa->sa_flags & SA_RESTART)) 443 goto no_system_call_restart; 444 /* fallthrough */ 445 case ERESTARTNOINTR: 446 regs->u_regs[UREG_I0] = orig_i0; 447 regs->pc -= 4; 448 regs->npc -= 4; 449 } 450 } 451 452 /* Note that 'init' is a special process: it doesn't get signals it doesn't 453 * want to handle. Thus you cannot kill init even with a SIGKILL even by 454 * mistake. 455 */ 456 static void do_signal(struct pt_regs *regs, unsigned long orig_i0) 457 { 458 struct ksignal ksig; 459 int restart_syscall; 460 bool has_handler; 461 462 /* It's a lot of work and synchronization to add a new ptrace 463 * register for GDB to save and restore in order to get 464 * orig_i0 correct for syscall restarts when debugging. 465 * 466 * Although it should be the case that most of the global 467 * registers are volatile across a system call, glibc already 468 * depends upon that fact that we preserve them. So we can't 469 * just use any global register to save away the orig_i0 value. 470 * 471 * In particular %g2, %g3, %g4, and %g5 are all assumed to be 472 * preserved across a system call trap by various pieces of 473 * code in glibc. 474 * 475 * %g7 is used as the "thread register". %g6 is not used in 476 * any fixed manner. %g6 is used as a scratch register and 477 * a compiler temporary, but it's value is never used across 478 * a system call. Therefore %g6 is usable for orig_i0 storage. 479 */ 480 if (pt_regs_is_syscall(regs) && (regs->psr & PSR_C)) 481 regs->u_regs[UREG_G6] = orig_i0; 482 483 has_handler = get_signal(&ksig); 484 485 /* If the debugger messes with the program counter, it clears 486 * the software "in syscall" bit, directing us to not perform 487 * a syscall restart. 488 */ 489 restart_syscall = 0; 490 if (pt_regs_is_syscall(regs) && (regs->psr & PSR_C)) { 491 restart_syscall = 1; 492 orig_i0 = regs->u_regs[UREG_G6]; 493 } 494 495 if (has_handler) { 496 if (restart_syscall) 497 syscall_restart(orig_i0, regs, &ksig.ka.sa); 498 handle_signal(&ksig, regs); 499 } else { 500 if (restart_syscall) { 501 switch (regs->u_regs[UREG_I0]) { 502 case ERESTARTNOHAND: 503 case ERESTARTSYS: 504 case ERESTARTNOINTR: 505 /* replay the system call when we are done */ 506 regs->u_regs[UREG_I0] = orig_i0; 507 regs->pc -= 4; 508 regs->npc -= 4; 509 pt_regs_clear_syscall(regs); 510 /* fall through */ 511 case ERESTART_RESTARTBLOCK: 512 regs->u_regs[UREG_G1] = __NR_restart_syscall; 513 regs->pc -= 4; 514 regs->npc -= 4; 515 pt_regs_clear_syscall(regs); 516 } 517 } 518 restore_saved_sigmask(); 519 } 520 } 521 522 void do_notify_resume(struct pt_regs *regs, unsigned long orig_i0, 523 unsigned long thread_info_flags) 524 { 525 if (thread_info_flags & _TIF_SIGPENDING) 526 do_signal(regs, orig_i0); 527 if (thread_info_flags & _TIF_NOTIFY_RESUME) { 528 clear_thread_flag(TIF_NOTIFY_RESUME); 529 tracehook_notify_resume(regs); 530 } 531 } 532 533 asmlinkage int do_sys_sigstack(struct sigstack __user *ssptr, 534 struct sigstack __user *ossptr, 535 unsigned long sp) 536 { 537 int ret = -EFAULT; 538 539 /* First see if old state is wanted. */ 540 if (ossptr) { 541 if (put_user(current->sas_ss_sp + current->sas_ss_size, 542 &ossptr->the_stack) || 543 __put_user(on_sig_stack(sp), &ossptr->cur_status)) 544 goto out; 545 } 546 547 /* Now see if we want to update the new state. */ 548 if (ssptr) { 549 char *ss_sp; 550 551 if (get_user(ss_sp, &ssptr->the_stack)) 552 goto out; 553 /* If the current stack was set with sigaltstack, don't 554 swap stacks while we are on it. */ 555 ret = -EPERM; 556 if (current->sas_ss_sp && on_sig_stack(sp)) 557 goto out; 558 559 /* Since we don't know the extent of the stack, and we don't 560 track onstack-ness, but rather calculate it, we must 561 presume a size. Ho hum this interface is lossy. */ 562 current->sas_ss_sp = (unsigned long)ss_sp - SIGSTKSZ; 563 current->sas_ss_size = SIGSTKSZ; 564 } 565 ret = 0; 566 out: 567 return ret; 568 } 569