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/config.h> 16 #include <linux/sched.h> 17 #include <linux/mm.h> 18 #include <linux/smp.h> 19 #include <linux/smp_lock.h> 20 #include <linux/kernel.h> 21 #include <linux/signal.h> 22 #include <linux/errno.h> 23 #include <linux/wait.h> 24 #include <linux/unistd.h> 25 #include <linux/stddef.h> 26 #include <linux/elf.h> 27 #include <linux/ptrace.h> 28 #include <linux/module.h> 29 30 #include <asm/sigcontext.h> 31 #include <asm/ucontext.h> 32 #include <asm/uaccess.h> 33 #include <asm/pgtable.h> 34 #include <asm/unistd.h> 35 #include <asm/cacheflush.h> 36 #include <asm/syscalls.h> 37 #include <asm/vdso.h> 38 39 #define DEBUG_SIG 0 40 41 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP))) 42 43 #define GP_REGS_SIZE min(sizeof(elf_gregset_t), sizeof(struct pt_regs)) 44 #define FP_REGS_SIZE sizeof(elf_fpregset_t) 45 46 #define TRAMP_TRACEBACK 3 47 #define TRAMP_SIZE 6 48 49 /* 50 * When we have signals to deliver, we set up on the user stack, 51 * going down from the original stack pointer: 52 * 1) a rt_sigframe struct which contains the ucontext 53 * 2) a gap of __SIGNAL_FRAMESIZE bytes which acts as a dummy caller 54 * frame for the signal handler. 55 */ 56 57 struct rt_sigframe { 58 /* sys_rt_sigreturn requires the ucontext be the first field */ 59 struct ucontext uc; 60 unsigned long _unused[2]; 61 unsigned int tramp[TRAMP_SIZE]; 62 struct siginfo __user *pinfo; 63 void __user *puc; 64 struct siginfo info; 65 /* 64 bit ABI allows for 288 bytes below sp before decrementing it. */ 66 char abigap[288]; 67 } __attribute__ ((aligned (16))); 68 69 long sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss, unsigned long r5, 70 unsigned long r6, unsigned long r7, unsigned long r8, 71 struct pt_regs *regs) 72 { 73 return do_sigaltstack(uss, uoss, regs->gpr[1]); 74 } 75 76 77 /* 78 * Set up the sigcontext for the signal frame. 79 */ 80 81 static long setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs, 82 int signr, sigset_t *set, unsigned long handler) 83 { 84 /* When CONFIG_ALTIVEC is set, we _always_ setup v_regs even if the 85 * process never used altivec yet (MSR_VEC is zero in pt_regs of 86 * the context). This is very important because we must ensure we 87 * don't lose the VRSAVE content that may have been set prior to 88 * the process doing its first vector operation 89 * Userland shall check AT_HWCAP to know wether it can rely on the 90 * v_regs pointer or not 91 */ 92 #ifdef CONFIG_ALTIVEC 93 elf_vrreg_t __user *v_regs = (elf_vrreg_t __user *)(((unsigned long)sc->vmx_reserve + 15) & ~0xful); 94 #endif 95 long err = 0; 96 97 flush_fp_to_thread(current); 98 99 #ifdef CONFIG_ALTIVEC 100 err |= __put_user(v_regs, &sc->v_regs); 101 102 /* save altivec registers */ 103 if (current->thread.used_vr) { 104 flush_altivec_to_thread(current); 105 /* Copy 33 vec registers (vr0..31 and vscr) to the stack */ 106 err |= __copy_to_user(v_regs, current->thread.vr, 33 * sizeof(vector128)); 107 /* set MSR_VEC in the MSR value in the frame to indicate that sc->v_reg) 108 * contains valid data. 109 */ 110 regs->msr |= MSR_VEC; 111 } 112 /* We always copy to/from vrsave, it's 0 if we don't have or don't 113 * use altivec. 114 */ 115 err |= __put_user(current->thread.vrsave, (u32 __user *)&v_regs[33]); 116 #else /* CONFIG_ALTIVEC */ 117 err |= __put_user(0, &sc->v_regs); 118 #endif /* CONFIG_ALTIVEC */ 119 err |= __put_user(&sc->gp_regs, &sc->regs); 120 WARN_ON(!FULL_REGS(regs)); 121 err |= __copy_to_user(&sc->gp_regs, regs, GP_REGS_SIZE); 122 err |= __copy_to_user(&sc->fp_regs, ¤t->thread.fpr, FP_REGS_SIZE); 123 err |= __put_user(signr, &sc->signal); 124 err |= __put_user(handler, &sc->handler); 125 if (set != NULL) 126 err |= __put_user(set->sig[0], &sc->oldmask); 127 128 return err; 129 } 130 131 /* 132 * Restore the sigcontext from the signal frame. 133 */ 134 135 static long restore_sigcontext(struct pt_regs *regs, sigset_t *set, int sig, 136 struct sigcontext __user *sc) 137 { 138 #ifdef CONFIG_ALTIVEC 139 elf_vrreg_t __user *v_regs; 140 #endif 141 unsigned long err = 0; 142 unsigned long save_r13 = 0; 143 elf_greg_t *gregs = (elf_greg_t *)regs; 144 unsigned long msr; 145 int i; 146 147 /* If this is not a signal return, we preserve the TLS in r13 */ 148 if (!sig) 149 save_r13 = regs->gpr[13]; 150 151 /* copy everything before MSR */ 152 err |= __copy_from_user(regs, &sc->gp_regs, 153 PT_MSR*sizeof(unsigned long)); 154 155 /* get MSR separately, transfer the LE bit if doing signal return */ 156 err |= __get_user(msr, &sc->gp_regs[PT_MSR]); 157 if (sig) 158 regs->msr = (regs->msr & ~MSR_LE) | (msr & MSR_LE); 159 160 /* skip SOFTE */ 161 for (i = PT_MSR+1; i <= PT_RESULT; i++) { 162 if (i == PT_SOFTE) 163 continue; 164 err |= __get_user(gregs[i], &sc->gp_regs[i]); 165 } 166 167 if (!sig) 168 regs->gpr[13] = save_r13; 169 if (set != NULL) 170 err |= __get_user(set->sig[0], &sc->oldmask); 171 172 /* 173 * Do this before updating the thread state in 174 * current->thread.fpr/vr. That way, if we get preempted 175 * and another task grabs the FPU/Altivec, it won't be 176 * tempted to save the current CPU state into the thread_struct 177 * and corrupt what we are writing there. 178 */ 179 discard_lazy_cpu_state(); 180 181 err |= __copy_from_user(¤t->thread.fpr, &sc->fp_regs, FP_REGS_SIZE); 182 183 #ifdef CONFIG_ALTIVEC 184 err |= __get_user(v_regs, &sc->v_regs); 185 if (err) 186 return err; 187 if (v_regs && !access_ok(VERIFY_READ, v_regs, 34 * sizeof(vector128))) 188 return -EFAULT; 189 /* Copy 33 vec registers (vr0..31 and vscr) from the stack */ 190 if (v_regs != 0 && (msr & MSR_VEC) != 0) 191 err |= __copy_from_user(current->thread.vr, v_regs, 192 33 * sizeof(vector128)); 193 else if (current->thread.used_vr) 194 memset(current->thread.vr, 0, 33 * sizeof(vector128)); 195 /* Always get VRSAVE back */ 196 if (v_regs != 0) 197 err |= __get_user(current->thread.vrsave, (u32 __user *)&v_regs[33]); 198 else 199 current->thread.vrsave = 0; 200 #endif /* CONFIG_ALTIVEC */ 201 202 /* Force reload of FP/VEC */ 203 regs->msr &= ~(MSR_FP | MSR_FE0 | MSR_FE1 | MSR_VEC); 204 205 return err; 206 } 207 208 /* 209 * Allocate space for the signal frame 210 */ 211 static inline void __user * get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, 212 size_t frame_size) 213 { 214 unsigned long newsp; 215 216 /* Default to using normal stack */ 217 newsp = regs->gpr[1]; 218 219 if ((ka->sa.sa_flags & SA_ONSTACK) && current->sas_ss_size) { 220 if (! on_sig_stack(regs->gpr[1])) 221 newsp = (current->sas_ss_sp + current->sas_ss_size); 222 } 223 224 return (void __user *)((newsp - frame_size) & -16ul); 225 } 226 227 /* 228 * Setup the trampoline code on the stack 229 */ 230 static long setup_trampoline(unsigned int syscall, unsigned int __user *tramp) 231 { 232 int i; 233 long err = 0; 234 235 /* addi r1, r1, __SIGNAL_FRAMESIZE # Pop the dummy stackframe */ 236 err |= __put_user(0x38210000UL | (__SIGNAL_FRAMESIZE & 0xffff), &tramp[0]); 237 /* li r0, __NR_[rt_]sigreturn| */ 238 err |= __put_user(0x38000000UL | (syscall & 0xffff), &tramp[1]); 239 /* sc */ 240 err |= __put_user(0x44000002UL, &tramp[2]); 241 242 /* Minimal traceback info */ 243 for (i=TRAMP_TRACEBACK; i < TRAMP_SIZE ;i++) 244 err |= __put_user(0, &tramp[i]); 245 246 if (!err) 247 flush_icache_range((unsigned long) &tramp[0], 248 (unsigned long) &tramp[TRAMP_SIZE]); 249 250 return err; 251 } 252 253 /* 254 * Restore the user process's signal mask (also used by signal32.c) 255 */ 256 void restore_sigmask(sigset_t *set) 257 { 258 sigdelsetmask(set, ~_BLOCKABLE); 259 spin_lock_irq(¤t->sighand->siglock); 260 current->blocked = *set; 261 recalc_sigpending(); 262 spin_unlock_irq(¤t->sighand->siglock); 263 } 264 265 266 /* 267 * Handle {get,set,swap}_context operations 268 */ 269 int sys_swapcontext(struct ucontext __user *old_ctx, 270 struct ucontext __user *new_ctx, 271 long ctx_size, long r6, long r7, long r8, struct pt_regs *regs) 272 { 273 unsigned char tmp; 274 sigset_t set; 275 276 /* Context size is for future use. Right now, we only make sure 277 * we are passed something we understand 278 */ 279 if (ctx_size < sizeof(struct ucontext)) 280 return -EINVAL; 281 282 if (old_ctx != NULL) { 283 if (!access_ok(VERIFY_WRITE, old_ctx, sizeof(*old_ctx)) 284 || setup_sigcontext(&old_ctx->uc_mcontext, regs, 0, NULL, 0) 285 || __copy_to_user(&old_ctx->uc_sigmask, 286 ¤t->blocked, sizeof(sigset_t))) 287 return -EFAULT; 288 } 289 if (new_ctx == NULL) 290 return 0; 291 if (!access_ok(VERIFY_READ, new_ctx, sizeof(*new_ctx)) 292 || __get_user(tmp, (u8 __user *) new_ctx) 293 || __get_user(tmp, (u8 __user *) (new_ctx + 1) - 1)) 294 return -EFAULT; 295 296 /* 297 * If we get a fault copying the context into the kernel's 298 * image of the user's registers, we can't just return -EFAULT 299 * because the user's registers will be corrupted. For instance 300 * the NIP value may have been updated but not some of the 301 * other registers. Given that we have done the access_ok 302 * and successfully read the first and last bytes of the region 303 * above, this should only happen in an out-of-memory situation 304 * or if another thread unmaps the region containing the context. 305 * We kill the task with a SIGSEGV in this situation. 306 */ 307 308 if (__copy_from_user(&set, &new_ctx->uc_sigmask, sizeof(set))) 309 do_exit(SIGSEGV); 310 restore_sigmask(&set); 311 if (restore_sigcontext(regs, NULL, 0, &new_ctx->uc_mcontext)) 312 do_exit(SIGSEGV); 313 314 /* This returns like rt_sigreturn */ 315 set_thread_flag(TIF_RESTOREALL); 316 return 0; 317 } 318 319 320 /* 321 * Do a signal return; undo the signal stack. 322 */ 323 324 int sys_rt_sigreturn(unsigned long r3, unsigned long r4, unsigned long r5, 325 unsigned long r6, unsigned long r7, unsigned long r8, 326 struct pt_regs *regs) 327 { 328 struct ucontext __user *uc = (struct ucontext __user *)regs->gpr[1]; 329 sigset_t set; 330 331 /* Always make any pending restarted system calls return -EINTR */ 332 current_thread_info()->restart_block.fn = do_no_restart_syscall; 333 334 if (!access_ok(VERIFY_READ, uc, sizeof(*uc))) 335 goto badframe; 336 337 if (__copy_from_user(&set, &uc->uc_sigmask, sizeof(set))) 338 goto badframe; 339 restore_sigmask(&set); 340 if (restore_sigcontext(regs, NULL, 1, &uc->uc_mcontext)) 341 goto badframe; 342 343 /* do_sigaltstack expects a __user pointer and won't modify 344 * what's in there anyway 345 */ 346 do_sigaltstack(&uc->uc_stack, NULL, regs->gpr[1]); 347 348 set_thread_flag(TIF_RESTOREALL); 349 return 0; 350 351 badframe: 352 #if DEBUG_SIG 353 printk("badframe in sys_rt_sigreturn, regs=%p uc=%p &uc->uc_mcontext=%p\n", 354 regs, uc, &uc->uc_mcontext); 355 #endif 356 force_sig(SIGSEGV, current); 357 return 0; 358 } 359 360 static int setup_rt_frame(int signr, struct k_sigaction *ka, siginfo_t *info, 361 sigset_t *set, struct pt_regs *regs) 362 { 363 /* Handler is *really* a pointer to the function descriptor for 364 * the signal routine. The first entry in the function 365 * descriptor is the entry address of signal and the second 366 * entry is the TOC value we need to use. 367 */ 368 func_descr_t __user *funct_desc_ptr; 369 struct rt_sigframe __user *frame; 370 unsigned long newsp = 0; 371 long err = 0; 372 373 frame = get_sigframe(ka, regs, sizeof(*frame)); 374 375 if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame))) 376 goto badframe; 377 378 err |= __put_user(&frame->info, &frame->pinfo); 379 err |= __put_user(&frame->uc, &frame->puc); 380 err |= copy_siginfo_to_user(&frame->info, info); 381 if (err) 382 goto badframe; 383 384 /* Create the ucontext. */ 385 err |= __put_user(0, &frame->uc.uc_flags); 386 err |= __put_user(0, &frame->uc.uc_link); 387 err |= __put_user(current->sas_ss_sp, &frame->uc.uc_stack.ss_sp); 388 err |= __put_user(sas_ss_flags(regs->gpr[1]), 389 &frame->uc.uc_stack.ss_flags); 390 err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size); 391 err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, signr, NULL, 392 (unsigned long)ka->sa.sa_handler); 393 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)); 394 if (err) 395 goto badframe; 396 397 /* Make sure signal handler doesn't get spurious FP exceptions */ 398 current->thread.fpscr.val = 0; 399 400 /* Set up to return from userspace. */ 401 if (vdso64_rt_sigtramp && current->mm->context.vdso_base) { 402 regs->link = current->mm->context.vdso_base + vdso64_rt_sigtramp; 403 } else { 404 err |= setup_trampoline(__NR_rt_sigreturn, &frame->tramp[0]); 405 if (err) 406 goto badframe; 407 regs->link = (unsigned long) &frame->tramp[0]; 408 } 409 funct_desc_ptr = (func_descr_t __user *) ka->sa.sa_handler; 410 411 /* Allocate a dummy caller frame for the signal handler. */ 412 newsp = (unsigned long)frame - __SIGNAL_FRAMESIZE; 413 err |= put_user(regs->gpr[1], (unsigned long __user *)newsp); 414 415 /* Set up "regs" so we "return" to the signal handler. */ 416 err |= get_user(regs->nip, &funct_desc_ptr->entry); 417 /* enter the signal handler in big-endian mode */ 418 regs->msr &= ~MSR_LE; 419 regs->gpr[1] = newsp; 420 err |= get_user(regs->gpr[2], &funct_desc_ptr->toc); 421 regs->gpr[3] = signr; 422 regs->result = 0; 423 if (ka->sa.sa_flags & SA_SIGINFO) { 424 err |= get_user(regs->gpr[4], (unsigned long __user *)&frame->pinfo); 425 err |= get_user(regs->gpr[5], (unsigned long __user *)&frame->puc); 426 regs->gpr[6] = (unsigned long) frame; 427 } else { 428 regs->gpr[4] = (unsigned long)&frame->uc.uc_mcontext; 429 } 430 if (err) 431 goto badframe; 432 433 return 1; 434 435 badframe: 436 #if DEBUG_SIG 437 printk("badframe in setup_rt_frame, regs=%p frame=%p newsp=%lx\n", 438 regs, frame, newsp); 439 #endif 440 force_sigsegv(signr, current); 441 return 0; 442 } 443 444 445 /* 446 * OK, we're invoking a handler 447 */ 448 static int handle_signal(unsigned long sig, struct k_sigaction *ka, 449 siginfo_t *info, sigset_t *oldset, struct pt_regs *regs) 450 { 451 int ret; 452 453 /* Set up Signal Frame */ 454 ret = setup_rt_frame(sig, ka, info, oldset, regs); 455 456 if (ret) { 457 spin_lock_irq(¤t->sighand->siglock); 458 sigorsets(¤t->blocked, ¤t->blocked, &ka->sa.sa_mask); 459 if (!(ka->sa.sa_flags & SA_NODEFER)) 460 sigaddset(¤t->blocked,sig); 461 recalc_sigpending(); 462 spin_unlock_irq(¤t->sighand->siglock); 463 } 464 465 return ret; 466 } 467 468 static inline void syscall_restart(struct pt_regs *regs, struct k_sigaction *ka) 469 { 470 switch ((int)regs->result) { 471 case -ERESTART_RESTARTBLOCK: 472 case -ERESTARTNOHAND: 473 /* ERESTARTNOHAND means that the syscall should only be 474 * restarted if there was no handler for the signal, and since 475 * we only get here if there is a handler, we dont restart. 476 */ 477 regs->result = -EINTR; 478 regs->gpr[3] = EINTR; 479 regs->ccr |= 0x10000000; 480 break; 481 case -ERESTARTSYS: 482 /* ERESTARTSYS means to restart the syscall if there is no 483 * handler or the handler was registered with SA_RESTART 484 */ 485 if (!(ka->sa.sa_flags & SA_RESTART)) { 486 regs->result = -EINTR; 487 regs->gpr[3] = EINTR; 488 regs->ccr |= 0x10000000; 489 break; 490 } 491 /* fallthrough */ 492 case -ERESTARTNOINTR: 493 /* ERESTARTNOINTR means that the syscall should be 494 * called again after the signal handler returns. 495 */ 496 regs->gpr[3] = regs->orig_gpr3; 497 regs->nip -= 4; 498 regs->result = 0; 499 break; 500 } 501 } 502 503 /* 504 * Note that 'init' is a special process: it doesn't get signals it doesn't 505 * want to handle. Thus you cannot kill init even with a SIGKILL even by 506 * mistake. 507 */ 508 int do_signal(sigset_t *oldset, struct pt_regs *regs) 509 { 510 siginfo_t info; 511 int signr; 512 struct k_sigaction ka; 513 514 /* 515 * If the current thread is 32 bit - invoke the 516 * 32 bit signal handling code 517 */ 518 if (test_thread_flag(TIF_32BIT)) 519 return do_signal32(oldset, regs); 520 521 if (test_thread_flag(TIF_RESTORE_SIGMASK)) 522 oldset = ¤t->saved_sigmask; 523 else if (!oldset) 524 oldset = ¤t->blocked; 525 526 signr = get_signal_to_deliver(&info, &ka, regs, NULL); 527 if (signr > 0) { 528 int ret; 529 530 /* Whee! Actually deliver the signal. */ 531 if (TRAP(regs) == 0x0C00) 532 syscall_restart(regs, &ka); 533 534 /* 535 * Reenable the DABR before delivering the signal to 536 * user space. The DABR will have been cleared if it 537 * triggered inside the kernel. 538 */ 539 if (current->thread.dabr) 540 set_dabr(current->thread.dabr); 541 542 ret = handle_signal(signr, &ka, &info, oldset, regs); 543 544 /* If a signal was successfully delivered, the saved sigmask is in 545 its frame, and we can clear the TIF_RESTORE_SIGMASK flag */ 546 if (ret && test_thread_flag(TIF_RESTORE_SIGMASK)) 547 clear_thread_flag(TIF_RESTORE_SIGMASK); 548 549 return ret; 550 } 551 552 if (TRAP(regs) == 0x0C00) { /* System Call! */ 553 if ((int)regs->result == -ERESTARTNOHAND || 554 (int)regs->result == -ERESTARTSYS || 555 (int)regs->result == -ERESTARTNOINTR) { 556 regs->gpr[3] = regs->orig_gpr3; 557 regs->nip -= 4; /* Back up & retry system call */ 558 regs->result = 0; 559 } else if ((int)regs->result == -ERESTART_RESTARTBLOCK) { 560 regs->gpr[0] = __NR_restart_syscall; 561 regs->nip -= 4; 562 regs->result = 0; 563 } 564 } 565 /* No signal to deliver -- put the saved sigmask back */ 566 if (test_thread_flag(TIF_RESTORE_SIGMASK)) { 567 clear_thread_flag(TIF_RESTORE_SIGMASK); 568 sigprocmask(SIG_SETMASK, ¤t->saved_sigmask, NULL); 569 } 570 571 return 0; 572 } 573 EXPORT_SYMBOL(do_signal); 574