1 /* 2 * PowerPC version 3 * Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org) 4 * 5 * Derived from "arch/i386/kernel/signal.c" 6 * Copyright (C) 1991, 1992 Linus Torvalds 7 * 1997-11-28 Modified for POSIX.1b signals by Richard Henderson 8 * 9 * This program is free software; you can redistribute it and/or 10 * modify it under the terms of the GNU General Public License 11 * as published by the Free Software Foundation; either version 12 * 2 of the License, or (at your option) any later version. 13 */ 14 15 #include <linux/sched.h> 16 #include <linux/mm.h> 17 #include <linux/smp.h> 18 #include <linux/smp_lock.h> 19 #include <linux/kernel.h> 20 #include <linux/signal.h> 21 #include <linux/errno.h> 22 #include <linux/wait.h> 23 #include <linux/unistd.h> 24 #include <linux/stddef.h> 25 #include <linux/elf.h> 26 #include <linux/ptrace.h> 27 #include <linux/module.h> 28 29 #include <asm/sigcontext.h> 30 #include <asm/ucontext.h> 31 #include <asm/uaccess.h> 32 #include <asm/pgtable.h> 33 #include <asm/unistd.h> 34 #include <asm/cacheflush.h> 35 #include <asm/syscalls.h> 36 #include <asm/vdso.h> 37 38 #define DEBUG_SIG 0 39 40 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP))) 41 42 #define GP_REGS_SIZE min(sizeof(elf_gregset_t), sizeof(struct pt_regs)) 43 #define FP_REGS_SIZE sizeof(elf_fpregset_t) 44 45 #define TRAMP_TRACEBACK 3 46 #define TRAMP_SIZE 6 47 48 /* 49 * When we have signals to deliver, we set up on the user stack, 50 * going down from the original stack pointer: 51 * 1) a rt_sigframe struct which contains the ucontext 52 * 2) a gap of __SIGNAL_FRAMESIZE bytes which acts as a dummy caller 53 * frame for the signal handler. 54 */ 55 56 struct rt_sigframe { 57 /* sys_rt_sigreturn requires the ucontext be the first field */ 58 struct ucontext uc; 59 unsigned long _unused[2]; 60 unsigned int tramp[TRAMP_SIZE]; 61 struct siginfo __user *pinfo; 62 void __user *puc; 63 struct siginfo info; 64 /* 64 bit ABI allows for 288 bytes below sp before decrementing it. */ 65 char abigap[288]; 66 } __attribute__ ((aligned (16))); 67 68 long sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss, unsigned long r5, 69 unsigned long r6, unsigned long r7, unsigned long r8, 70 struct pt_regs *regs) 71 { 72 return do_sigaltstack(uss, uoss, regs->gpr[1]); 73 } 74 75 76 /* 77 * Set up the sigcontext for the signal frame. 78 */ 79 80 static long setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs, 81 int signr, sigset_t *set, unsigned long handler) 82 { 83 /* When CONFIG_ALTIVEC is set, we _always_ setup v_regs even if the 84 * process never used altivec yet (MSR_VEC is zero in pt_regs of 85 * the context). This is very important because we must ensure we 86 * don't lose the VRSAVE content that may have been set prior to 87 * the process doing its first vector operation 88 * Userland shall check AT_HWCAP to know wether it can rely on the 89 * v_regs pointer or not 90 */ 91 #ifdef CONFIG_ALTIVEC 92 elf_vrreg_t __user *v_regs = (elf_vrreg_t __user *)(((unsigned long)sc->vmx_reserve + 15) & ~0xful); 93 #endif 94 long err = 0; 95 96 flush_fp_to_thread(current); 97 98 #ifdef CONFIG_ALTIVEC 99 err |= __put_user(v_regs, &sc->v_regs); 100 101 /* save altivec registers */ 102 if (current->thread.used_vr) { 103 flush_altivec_to_thread(current); 104 /* Copy 33 vec registers (vr0..31 and vscr) to the stack */ 105 err |= __copy_to_user(v_regs, current->thread.vr, 33 * sizeof(vector128)); 106 /* set MSR_VEC in the MSR value in the frame to indicate that sc->v_reg) 107 * contains valid data. 108 */ 109 regs->msr |= MSR_VEC; 110 } 111 /* We always copy to/from vrsave, it's 0 if we don't have or don't 112 * use altivec. 113 */ 114 err |= __put_user(current->thread.vrsave, (u32 __user *)&v_regs[33]); 115 #else /* CONFIG_ALTIVEC */ 116 err |= __put_user(0, &sc->v_regs); 117 #endif /* CONFIG_ALTIVEC */ 118 err |= __put_user(&sc->gp_regs, &sc->regs); 119 WARN_ON(!FULL_REGS(regs)); 120 err |= __copy_to_user(&sc->gp_regs, regs, GP_REGS_SIZE); 121 err |= __copy_to_user(&sc->fp_regs, ¤t->thread.fpr, FP_REGS_SIZE); 122 err |= __put_user(signr, &sc->signal); 123 err |= __put_user(handler, &sc->handler); 124 if (set != NULL) 125 err |= __put_user(set->sig[0], &sc->oldmask); 126 127 return err; 128 } 129 130 /* 131 * Restore the sigcontext from the signal frame. 132 */ 133 134 static long restore_sigcontext(struct pt_regs *regs, sigset_t *set, int sig, 135 struct sigcontext __user *sc) 136 { 137 #ifdef CONFIG_ALTIVEC 138 elf_vrreg_t __user *v_regs; 139 #endif 140 unsigned long err = 0; 141 unsigned long save_r13 = 0; 142 elf_greg_t *gregs = (elf_greg_t *)regs; 143 unsigned long msr; 144 int i; 145 146 /* If this is not a signal return, we preserve the TLS in r13 */ 147 if (!sig) 148 save_r13 = regs->gpr[13]; 149 150 /* copy everything before MSR */ 151 err |= __copy_from_user(regs, &sc->gp_regs, 152 PT_MSR*sizeof(unsigned long)); 153 154 /* get MSR separately, transfer the LE bit if doing signal return */ 155 err |= __get_user(msr, &sc->gp_regs[PT_MSR]); 156 if (sig) 157 regs->msr = (regs->msr & ~MSR_LE) | (msr & MSR_LE); 158 159 /* skip SOFTE */ 160 for (i = PT_MSR+1; i <= PT_RESULT; i++) { 161 if (i == PT_SOFTE) 162 continue; 163 err |= __get_user(gregs[i], &sc->gp_regs[i]); 164 } 165 166 if (!sig) 167 regs->gpr[13] = save_r13; 168 if (set != NULL) 169 err |= __get_user(set->sig[0], &sc->oldmask); 170 171 /* 172 * Do this before updating the thread state in 173 * current->thread.fpr/vr. That way, if we get preempted 174 * and another task grabs the FPU/Altivec, it won't be 175 * tempted to save the current CPU state into the thread_struct 176 * and corrupt what we are writing there. 177 */ 178 discard_lazy_cpu_state(); 179 180 err |= __copy_from_user(¤t->thread.fpr, &sc->fp_regs, FP_REGS_SIZE); 181 182 #ifdef CONFIG_ALTIVEC 183 err |= __get_user(v_regs, &sc->v_regs); 184 if (err) 185 return err; 186 if (v_regs && !access_ok(VERIFY_READ, v_regs, 34 * sizeof(vector128))) 187 return -EFAULT; 188 /* Copy 33 vec registers (vr0..31 and vscr) from the stack */ 189 if (v_regs != 0 && (msr & MSR_VEC) != 0) 190 err |= __copy_from_user(current->thread.vr, v_regs, 191 33 * sizeof(vector128)); 192 else if (current->thread.used_vr) 193 memset(current->thread.vr, 0, 33 * sizeof(vector128)); 194 /* Always get VRSAVE back */ 195 if (v_regs != 0) 196 err |= __get_user(current->thread.vrsave, (u32 __user *)&v_regs[33]); 197 else 198 current->thread.vrsave = 0; 199 #endif /* CONFIG_ALTIVEC */ 200 201 /* Force reload of FP/VEC */ 202 regs->msr &= ~(MSR_FP | MSR_FE0 | MSR_FE1 | MSR_VEC); 203 204 return err; 205 } 206 207 /* 208 * Allocate space for the signal frame 209 */ 210 static inline void __user * get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, 211 size_t frame_size) 212 { 213 unsigned long newsp; 214 215 /* Default to using normal stack */ 216 newsp = regs->gpr[1]; 217 218 if ((ka->sa.sa_flags & SA_ONSTACK) && current->sas_ss_size) { 219 if (! on_sig_stack(regs->gpr[1])) 220 newsp = (current->sas_ss_sp + current->sas_ss_size); 221 } 222 223 return (void __user *)((newsp - frame_size) & -16ul); 224 } 225 226 /* 227 * Setup the trampoline code on the stack 228 */ 229 static long setup_trampoline(unsigned int syscall, unsigned int __user *tramp) 230 { 231 int i; 232 long err = 0; 233 234 /* addi r1, r1, __SIGNAL_FRAMESIZE # Pop the dummy stackframe */ 235 err |= __put_user(0x38210000UL | (__SIGNAL_FRAMESIZE & 0xffff), &tramp[0]); 236 /* li r0, __NR_[rt_]sigreturn| */ 237 err |= __put_user(0x38000000UL | (syscall & 0xffff), &tramp[1]); 238 /* sc */ 239 err |= __put_user(0x44000002UL, &tramp[2]); 240 241 /* Minimal traceback info */ 242 for (i=TRAMP_TRACEBACK; i < TRAMP_SIZE ;i++) 243 err |= __put_user(0, &tramp[i]); 244 245 if (!err) 246 flush_icache_range((unsigned long) &tramp[0], 247 (unsigned long) &tramp[TRAMP_SIZE]); 248 249 return err; 250 } 251 252 /* 253 * Restore the user process's signal mask (also used by signal32.c) 254 */ 255 void restore_sigmask(sigset_t *set) 256 { 257 sigdelsetmask(set, ~_BLOCKABLE); 258 spin_lock_irq(¤t->sighand->siglock); 259 current->blocked = *set; 260 recalc_sigpending(); 261 spin_unlock_irq(¤t->sighand->siglock); 262 } 263 264 265 /* 266 * Handle {get,set,swap}_context operations 267 */ 268 int sys_swapcontext(struct ucontext __user *old_ctx, 269 struct ucontext __user *new_ctx, 270 long ctx_size, long r6, long r7, long r8, struct pt_regs *regs) 271 { 272 unsigned char tmp; 273 sigset_t set; 274 275 /* Context size is for future use. Right now, we only make sure 276 * we are passed something we understand 277 */ 278 if (ctx_size < sizeof(struct ucontext)) 279 return -EINVAL; 280 281 if (old_ctx != NULL) { 282 if (!access_ok(VERIFY_WRITE, old_ctx, sizeof(*old_ctx)) 283 || setup_sigcontext(&old_ctx->uc_mcontext, regs, 0, NULL, 0) 284 || __copy_to_user(&old_ctx->uc_sigmask, 285 ¤t->blocked, sizeof(sigset_t))) 286 return -EFAULT; 287 } 288 if (new_ctx == NULL) 289 return 0; 290 if (!access_ok(VERIFY_READ, new_ctx, sizeof(*new_ctx)) 291 || __get_user(tmp, (u8 __user *) new_ctx) 292 || __get_user(tmp, (u8 __user *) (new_ctx + 1) - 1)) 293 return -EFAULT; 294 295 /* 296 * If we get a fault copying the context into the kernel's 297 * image of the user's registers, we can't just return -EFAULT 298 * because the user's registers will be corrupted. For instance 299 * the NIP value may have been updated but not some of the 300 * other registers. Given that we have done the access_ok 301 * and successfully read the first and last bytes of the region 302 * above, this should only happen in an out-of-memory situation 303 * or if another thread unmaps the region containing the context. 304 * We kill the task with a SIGSEGV in this situation. 305 */ 306 307 if (__copy_from_user(&set, &new_ctx->uc_sigmask, sizeof(set))) 308 do_exit(SIGSEGV); 309 restore_sigmask(&set); 310 if (restore_sigcontext(regs, NULL, 0, &new_ctx->uc_mcontext)) 311 do_exit(SIGSEGV); 312 313 /* This returns like rt_sigreturn */ 314 set_thread_flag(TIF_RESTOREALL); 315 return 0; 316 } 317 318 319 /* 320 * Do a signal return; undo the signal stack. 321 */ 322 323 int sys_rt_sigreturn(unsigned long r3, unsigned long r4, unsigned long r5, 324 unsigned long r6, unsigned long r7, unsigned long r8, 325 struct pt_regs *regs) 326 { 327 struct ucontext __user *uc = (struct ucontext __user *)regs->gpr[1]; 328 sigset_t set; 329 330 /* Always make any pending restarted system calls return -EINTR */ 331 current_thread_info()->restart_block.fn = do_no_restart_syscall; 332 333 if (!access_ok(VERIFY_READ, uc, sizeof(*uc))) 334 goto badframe; 335 336 if (__copy_from_user(&set, &uc->uc_sigmask, sizeof(set))) 337 goto badframe; 338 restore_sigmask(&set); 339 if (restore_sigcontext(regs, NULL, 1, &uc->uc_mcontext)) 340 goto badframe; 341 342 /* do_sigaltstack expects a __user pointer and won't modify 343 * what's in there anyway 344 */ 345 do_sigaltstack(&uc->uc_stack, NULL, regs->gpr[1]); 346 347 set_thread_flag(TIF_RESTOREALL); 348 return 0; 349 350 badframe: 351 #if DEBUG_SIG 352 printk("badframe in sys_rt_sigreturn, regs=%p uc=%p &uc->uc_mcontext=%p\n", 353 regs, uc, &uc->uc_mcontext); 354 #endif 355 force_sig(SIGSEGV, current); 356 return 0; 357 } 358 359 static int setup_rt_frame(int signr, struct k_sigaction *ka, siginfo_t *info, 360 sigset_t *set, struct pt_regs *regs) 361 { 362 /* Handler is *really* a pointer to the function descriptor for 363 * the signal routine. The first entry in the function 364 * descriptor is the entry address of signal and the second 365 * entry is the TOC value we need to use. 366 */ 367 func_descr_t __user *funct_desc_ptr; 368 struct rt_sigframe __user *frame; 369 unsigned long newsp = 0; 370 long err = 0; 371 372 frame = get_sigframe(ka, regs, sizeof(*frame)); 373 374 if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame))) 375 goto badframe; 376 377 err |= __put_user(&frame->info, &frame->pinfo); 378 err |= __put_user(&frame->uc, &frame->puc); 379 err |= copy_siginfo_to_user(&frame->info, info); 380 if (err) 381 goto badframe; 382 383 /* Create the ucontext. */ 384 err |= __put_user(0, &frame->uc.uc_flags); 385 err |= __put_user(0, &frame->uc.uc_link); 386 err |= __put_user(current->sas_ss_sp, &frame->uc.uc_stack.ss_sp); 387 err |= __put_user(sas_ss_flags(regs->gpr[1]), 388 &frame->uc.uc_stack.ss_flags); 389 err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size); 390 err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, signr, NULL, 391 (unsigned long)ka->sa.sa_handler); 392 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)); 393 if (err) 394 goto badframe; 395 396 /* Make sure signal handler doesn't get spurious FP exceptions */ 397 current->thread.fpscr.val = 0; 398 399 /* Set up to return from userspace. */ 400 if (vdso64_rt_sigtramp && current->mm->context.vdso_base) { 401 regs->link = current->mm->context.vdso_base + vdso64_rt_sigtramp; 402 } else { 403 err |= setup_trampoline(__NR_rt_sigreturn, &frame->tramp[0]); 404 if (err) 405 goto badframe; 406 regs->link = (unsigned long) &frame->tramp[0]; 407 } 408 funct_desc_ptr = (func_descr_t __user *) ka->sa.sa_handler; 409 410 /* Allocate a dummy caller frame for the signal handler. */ 411 newsp = (unsigned long)frame - __SIGNAL_FRAMESIZE; 412 err |= put_user(regs->gpr[1], (unsigned long __user *)newsp); 413 414 /* Set up "regs" so we "return" to the signal handler. */ 415 err |= get_user(regs->nip, &funct_desc_ptr->entry); 416 /* enter the signal handler in big-endian mode */ 417 regs->msr &= ~MSR_LE; 418 regs->gpr[1] = newsp; 419 err |= get_user(regs->gpr[2], &funct_desc_ptr->toc); 420 regs->gpr[3] = signr; 421 regs->result = 0; 422 if (ka->sa.sa_flags & SA_SIGINFO) { 423 err |= get_user(regs->gpr[4], (unsigned long __user *)&frame->pinfo); 424 err |= get_user(regs->gpr[5], (unsigned long __user *)&frame->puc); 425 regs->gpr[6] = (unsigned long) frame; 426 } else { 427 regs->gpr[4] = (unsigned long)&frame->uc.uc_mcontext; 428 } 429 if (err) 430 goto badframe; 431 432 return 1; 433 434 badframe: 435 #if DEBUG_SIG 436 printk("badframe in setup_rt_frame, regs=%p frame=%p newsp=%lx\n", 437 regs, frame, newsp); 438 #endif 439 force_sigsegv(signr, current); 440 return 0; 441 } 442 443 444 /* 445 * OK, we're invoking a handler 446 */ 447 static int handle_signal(unsigned long sig, struct k_sigaction *ka, 448 siginfo_t *info, sigset_t *oldset, struct pt_regs *regs) 449 { 450 int ret; 451 452 /* Set up Signal Frame */ 453 ret = setup_rt_frame(sig, ka, info, oldset, regs); 454 455 if (ret) { 456 spin_lock_irq(¤t->sighand->siglock); 457 sigorsets(¤t->blocked, ¤t->blocked, &ka->sa.sa_mask); 458 if (!(ka->sa.sa_flags & SA_NODEFER)) 459 sigaddset(¤t->blocked,sig); 460 recalc_sigpending(); 461 spin_unlock_irq(¤t->sighand->siglock); 462 } 463 464 return ret; 465 } 466 467 static inline void syscall_restart(struct pt_regs *regs, struct k_sigaction *ka) 468 { 469 switch ((int)regs->result) { 470 case -ERESTART_RESTARTBLOCK: 471 case -ERESTARTNOHAND: 472 /* ERESTARTNOHAND means that the syscall should only be 473 * restarted if there was no handler for the signal, and since 474 * we only get here if there is a handler, we dont restart. 475 */ 476 regs->result = -EINTR; 477 regs->gpr[3] = EINTR; 478 regs->ccr |= 0x10000000; 479 break; 480 case -ERESTARTSYS: 481 /* ERESTARTSYS means to restart the syscall if there is no 482 * handler or the handler was registered with SA_RESTART 483 */ 484 if (!(ka->sa.sa_flags & SA_RESTART)) { 485 regs->result = -EINTR; 486 regs->gpr[3] = EINTR; 487 regs->ccr |= 0x10000000; 488 break; 489 } 490 /* fallthrough */ 491 case -ERESTARTNOINTR: 492 /* ERESTARTNOINTR means that the syscall should be 493 * called again after the signal handler returns. 494 */ 495 regs->gpr[3] = regs->orig_gpr3; 496 regs->nip -= 4; 497 regs->result = 0; 498 break; 499 } 500 } 501 502 /* 503 * Note that 'init' is a special process: it doesn't get signals it doesn't 504 * want to handle. Thus you cannot kill init even with a SIGKILL even by 505 * mistake. 506 */ 507 int do_signal(sigset_t *oldset, struct pt_regs *regs) 508 { 509 siginfo_t info; 510 int signr; 511 struct k_sigaction ka; 512 513 /* 514 * If the current thread is 32 bit - invoke the 515 * 32 bit signal handling code 516 */ 517 if (test_thread_flag(TIF_32BIT)) 518 return do_signal32(oldset, regs); 519 520 if (test_thread_flag(TIF_RESTORE_SIGMASK)) 521 oldset = ¤t->saved_sigmask; 522 else if (!oldset) 523 oldset = ¤t->blocked; 524 525 signr = get_signal_to_deliver(&info, &ka, regs, NULL); 526 if (signr > 0) { 527 int ret; 528 529 /* Whee! Actually deliver the signal. */ 530 if (TRAP(regs) == 0x0C00) 531 syscall_restart(regs, &ka); 532 533 /* 534 * Reenable the DABR before delivering the signal to 535 * user space. The DABR will have been cleared if it 536 * triggered inside the kernel. 537 */ 538 if (current->thread.dabr) 539 set_dabr(current->thread.dabr); 540 541 ret = handle_signal(signr, &ka, &info, oldset, regs); 542 543 /* If a signal was successfully delivered, the saved sigmask is in 544 its frame, and we can clear the TIF_RESTORE_SIGMASK flag */ 545 if (ret && test_thread_flag(TIF_RESTORE_SIGMASK)) 546 clear_thread_flag(TIF_RESTORE_SIGMASK); 547 548 return ret; 549 } 550 551 if (TRAP(regs) == 0x0C00) { /* System Call! */ 552 if ((int)regs->result == -ERESTARTNOHAND || 553 (int)regs->result == -ERESTARTSYS || 554 (int)regs->result == -ERESTARTNOINTR) { 555 regs->gpr[3] = regs->orig_gpr3; 556 regs->nip -= 4; /* Back up & retry system call */ 557 regs->result = 0; 558 } else if ((int)regs->result == -ERESTART_RESTARTBLOCK) { 559 regs->gpr[0] = __NR_restart_syscall; 560 regs->nip -= 4; 561 regs->result = 0; 562 } 563 } 564 /* No signal to deliver -- put the saved sigmask back */ 565 if (test_thread_flag(TIF_RESTORE_SIGMASK)) { 566 clear_thread_flag(TIF_RESTORE_SIGMASK); 567 sigprocmask(SIG_SETMASK, ¤t->saved_sigmask, NULL); 568 } 569 570 return 0; 571 } 572 EXPORT_SYMBOL(do_signal); 573