1 /* 2 * linux/arch/ppc64/kernel/signal.c 3 * 4 * PowerPC version 5 * Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org) 6 * 7 * Derived from "arch/i386/kernel/signal.c" 8 * Copyright (C) 1991, 1992 Linus Torvalds 9 * 1997-11-28 Modified for POSIX.1b signals by Richard Henderson 10 * 11 * This program is free software; you can redistribute it and/or 12 * modify it under the terms of the GNU General Public License 13 * as published by the Free Software Foundation; either version 14 * 2 of the License, or (at your option) any later version. 15 */ 16 17 #include <linux/config.h> 18 #include <linux/sched.h> 19 #include <linux/mm.h> 20 #include <linux/smp.h> 21 #include <linux/smp_lock.h> 22 #include <linux/kernel.h> 23 #include <linux/signal.h> 24 #include <linux/errno.h> 25 #include <linux/wait.h> 26 #include <linux/unistd.h> 27 #include <linux/stddef.h> 28 #include <linux/elf.h> 29 #include <linux/ptrace.h> 30 #include <linux/module.h> 31 32 #include <asm/sigcontext.h> 33 #include <asm/ucontext.h> 34 #include <asm/uaccess.h> 35 #include <asm/pgtable.h> 36 #include <asm/unistd.h> 37 #include <asm/cacheflush.h> 38 #include <asm/vdso.h> 39 40 #define DEBUG_SIG 0 41 42 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP))) 43 44 #define GP_REGS_SIZE min(sizeof(elf_gregset_t), sizeof(struct pt_regs)) 45 #define FP_REGS_SIZE sizeof(elf_fpregset_t) 46 47 #define TRAMP_TRACEBACK 3 48 #define TRAMP_SIZE 6 49 50 /* 51 * When we have signals to deliver, we set up on the user stack, 52 * going down from the original stack pointer: 53 * 1) a rt_sigframe struct which contains the ucontext 54 * 2) a gap of __SIGNAL_FRAMESIZE bytes which acts as a dummy caller 55 * frame for the signal handler. 56 */ 57 58 struct rt_sigframe { 59 /* sys_rt_sigreturn requires the ucontext be the first field */ 60 struct ucontext uc; 61 unsigned long _unused[2]; 62 unsigned int tramp[TRAMP_SIZE]; 63 struct siginfo __user *pinfo; 64 void __user *puc; 65 struct siginfo info; 66 /* 64 bit ABI allows for 288 bytes below sp before decrementing it. */ 67 char abigap[288]; 68 } __attribute__ ((aligned (16))); 69 70 long sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss, unsigned long r5, 71 unsigned long r6, unsigned long r7, unsigned long r8, 72 struct pt_regs *regs) 73 { 74 return do_sigaltstack(uss, uoss, regs->gpr[1]); 75 } 76 77 78 /* 79 * Set up the sigcontext for the signal frame. 80 */ 81 82 static long setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs, 83 int signr, sigset_t *set, unsigned long handler) 84 { 85 /* When CONFIG_ALTIVEC is set, we _always_ setup v_regs even if the 86 * process never used altivec yet (MSR_VEC is zero in pt_regs of 87 * the context). This is very important because we must ensure we 88 * don't lose the VRSAVE content that may have been set prior to 89 * the process doing its first vector operation 90 * Userland shall check AT_HWCAP to know wether it can rely on the 91 * v_regs pointer or not 92 */ 93 #ifdef CONFIG_ALTIVEC 94 elf_vrreg_t __user *v_regs = (elf_vrreg_t __user *)(((unsigned long)sc->vmx_reserve + 15) & ~0xful); 95 #endif 96 long err = 0; 97 98 flush_fp_to_thread(current); 99 100 #ifdef CONFIG_ALTIVEC 101 err |= __put_user(v_regs, &sc->v_regs); 102 103 /* save altivec registers */ 104 if (current->thread.used_vr) { 105 flush_altivec_to_thread(current); 106 /* Copy 33 vec registers (vr0..31 and vscr) to the stack */ 107 err |= __copy_to_user(v_regs, current->thread.vr, 33 * sizeof(vector128)); 108 /* set MSR_VEC in the MSR value in the frame to indicate that sc->v_reg) 109 * contains valid data. 110 */ 111 regs->msr |= MSR_VEC; 112 } 113 /* We always copy to/from vrsave, it's 0 if we don't have or don't 114 * use altivec. 115 */ 116 err |= __put_user(current->thread.vrsave, (u32 __user *)&v_regs[33]); 117 #else /* CONFIG_ALTIVEC */ 118 err |= __put_user(0, &sc->v_regs); 119 #endif /* CONFIG_ALTIVEC */ 120 err |= __put_user(&sc->gp_regs, &sc->regs); 121 WARN_ON(!FULL_REGS(regs)); 122 err |= __copy_to_user(&sc->gp_regs, regs, GP_REGS_SIZE); 123 err |= __copy_to_user(&sc->fp_regs, ¤t->thread.fpr, FP_REGS_SIZE); 124 err |= __put_user(signr, &sc->signal); 125 err |= __put_user(handler, &sc->handler); 126 if (set != NULL) 127 err |= __put_user(set->sig[0], &sc->oldmask); 128 129 return err; 130 } 131 132 /* 133 * Restore the sigcontext from the signal frame. 134 */ 135 136 static long restore_sigcontext(struct pt_regs *regs, sigset_t *set, int sig, 137 struct sigcontext __user *sc) 138 { 139 #ifdef CONFIG_ALTIVEC 140 elf_vrreg_t __user *v_regs; 141 #endif 142 unsigned long err = 0; 143 unsigned long save_r13 = 0; 144 elf_greg_t *gregs = (elf_greg_t *)regs; 145 #ifdef CONFIG_ALTIVEC 146 unsigned long msr; 147 #endif 148 int i; 149 150 /* If this is not a signal return, we preserve the TLS in r13 */ 151 if (!sig) 152 save_r13 = regs->gpr[13]; 153 154 /* copy everything before MSR */ 155 err |= __copy_from_user(regs, &sc->gp_regs, 156 PT_MSR*sizeof(unsigned long)); 157 158 /* skip MSR and SOFTE */ 159 for (i = PT_MSR+1; i <= PT_RESULT; i++) { 160 if (i == PT_SOFTE) 161 continue; 162 err |= __get_user(gregs[i], &sc->gp_regs[i]); 163 } 164 165 if (!sig) 166 regs->gpr[13] = save_r13; 167 if (set != NULL) 168 err |= __get_user(set->sig[0], &sc->oldmask); 169 170 /* 171 * Do this before updating the thread state in 172 * current->thread.fpr/vr. That way, if we get preempted 173 * and another task grabs the FPU/Altivec, it won't be 174 * tempted to save the current CPU state into the thread_struct 175 * and corrupt what we are writing there. 176 */ 177 discard_lazy_cpu_state(); 178 179 err |= __copy_from_user(¤t->thread.fpr, &sc->fp_regs, FP_REGS_SIZE); 180 181 #ifdef CONFIG_ALTIVEC 182 err |= __get_user(v_regs, &sc->v_regs); 183 err |= __get_user(msr, &sc->gp_regs[PT_MSR]); 184 if (err) 185 return err; 186 /* Copy 33 vec registers (vr0..31 and vscr) from the stack */ 187 if (v_regs != 0 && (msr & MSR_VEC) != 0) 188 err |= __copy_from_user(current->thread.vr, v_regs, 189 33 * sizeof(vector128)); 190 else if (current->thread.used_vr) 191 memset(current->thread.vr, 0, 33 * sizeof(vector128)); 192 /* Always get VRSAVE back */ 193 if (v_regs != 0) 194 err |= __get_user(current->thread.vrsave, (u32 __user *)&v_regs[33]); 195 else 196 current->thread.vrsave = 0; 197 #endif /* CONFIG_ALTIVEC */ 198 199 /* Force reload of FP/VEC */ 200 regs->msr &= ~(MSR_FP | MSR_FE0 | MSR_FE1 | MSR_VEC); 201 202 return err; 203 } 204 205 /* 206 * Allocate space for the signal frame 207 */ 208 static inline void __user * get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, 209 size_t frame_size) 210 { 211 unsigned long newsp; 212 213 /* Default to using normal stack */ 214 newsp = regs->gpr[1]; 215 216 if (ka->sa.sa_flags & SA_ONSTACK) { 217 if (! on_sig_stack(regs->gpr[1])) 218 newsp = (current->sas_ss_sp + current->sas_ss_size); 219 } 220 221 return (void __user *)((newsp - frame_size) & -16ul); 222 } 223 224 /* 225 * Setup the trampoline code on the stack 226 */ 227 static long setup_trampoline(unsigned int syscall, unsigned int __user *tramp) 228 { 229 int i; 230 long err = 0; 231 232 /* addi r1, r1, __SIGNAL_FRAMESIZE # Pop the dummy stackframe */ 233 err |= __put_user(0x38210000UL | (__SIGNAL_FRAMESIZE & 0xffff), &tramp[0]); 234 /* li r0, __NR_[rt_]sigreturn| */ 235 err |= __put_user(0x38000000UL | (syscall & 0xffff), &tramp[1]); 236 /* sc */ 237 err |= __put_user(0x44000002UL, &tramp[2]); 238 239 /* Minimal traceback info */ 240 for (i=TRAMP_TRACEBACK; i < TRAMP_SIZE ;i++) 241 err |= __put_user(0, &tramp[i]); 242 243 if (!err) 244 flush_icache_range((unsigned long) &tramp[0], 245 (unsigned long) &tramp[TRAMP_SIZE]); 246 247 return err; 248 } 249 250 /* 251 * Restore the user process's signal mask (also used by signal32.c) 252 */ 253 void restore_sigmask(sigset_t *set) 254 { 255 sigdelsetmask(set, ~_BLOCKABLE); 256 spin_lock_irq(¤t->sighand->siglock); 257 current->blocked = *set; 258 recalc_sigpending(); 259 spin_unlock_irq(¤t->sighand->siglock); 260 } 261 262 263 /* 264 * Handle {get,set,swap}_context operations 265 */ 266 int sys_swapcontext(struct ucontext __user *old_ctx, 267 struct ucontext __user *new_ctx, 268 long ctx_size, long r6, long r7, long r8, struct pt_regs *regs) 269 { 270 unsigned char tmp; 271 sigset_t set; 272 273 /* Context size is for future use. Right now, we only make sure 274 * we are passed something we understand 275 */ 276 if (ctx_size < sizeof(struct ucontext)) 277 return -EINVAL; 278 279 if (old_ctx != NULL) { 280 if (!access_ok(VERIFY_WRITE, old_ctx, sizeof(*old_ctx)) 281 || setup_sigcontext(&old_ctx->uc_mcontext, regs, 0, NULL, 0) 282 || __copy_to_user(&old_ctx->uc_sigmask, 283 ¤t->blocked, sizeof(sigset_t))) 284 return -EFAULT; 285 } 286 if (new_ctx == NULL) 287 return 0; 288 if (!access_ok(VERIFY_READ, new_ctx, sizeof(*new_ctx)) 289 || __get_user(tmp, (u8 __user *) new_ctx) 290 || __get_user(tmp, (u8 __user *) (new_ctx + 1) - 1)) 291 return -EFAULT; 292 293 /* 294 * If we get a fault copying the context into the kernel's 295 * image of the user's registers, we can't just return -EFAULT 296 * because the user's registers will be corrupted. For instance 297 * the NIP value may have been updated but not some of the 298 * other registers. Given that we have done the access_ok 299 * and successfully read the first and last bytes of the region 300 * above, this should only happen in an out-of-memory situation 301 * or if another thread unmaps the region containing the context. 302 * We kill the task with a SIGSEGV in this situation. 303 */ 304 305 if (__copy_from_user(&set, &new_ctx->uc_sigmask, sizeof(set))) 306 do_exit(SIGSEGV); 307 restore_sigmask(&set); 308 if (restore_sigcontext(regs, NULL, 0, &new_ctx->uc_mcontext)) 309 do_exit(SIGSEGV); 310 311 /* This returns like rt_sigreturn */ 312 set_thread_flag(TIF_RESTOREALL); 313 return 0; 314 } 315 316 317 /* 318 * Do a signal return; undo the signal stack. 319 */ 320 321 int sys_rt_sigreturn(unsigned long r3, unsigned long r4, unsigned long r5, 322 unsigned long r6, unsigned long r7, unsigned long r8, 323 struct pt_regs *regs) 324 { 325 struct ucontext __user *uc = (struct ucontext __user *)regs->gpr[1]; 326 sigset_t set; 327 328 /* Always make any pending restarted system calls return -EINTR */ 329 current_thread_info()->restart_block.fn = do_no_restart_syscall; 330 331 if (!access_ok(VERIFY_READ, uc, sizeof(*uc))) 332 goto badframe; 333 334 if (__copy_from_user(&set, &uc->uc_sigmask, sizeof(set))) 335 goto badframe; 336 restore_sigmask(&set); 337 if (restore_sigcontext(regs, NULL, 1, &uc->uc_mcontext)) 338 goto badframe; 339 340 /* do_sigaltstack expects a __user pointer and won't modify 341 * what's in there anyway 342 */ 343 do_sigaltstack(&uc->uc_stack, NULL, regs->gpr[1]); 344 345 set_thread_flag(TIF_RESTOREALL); 346 return 0; 347 348 badframe: 349 #if DEBUG_SIG 350 printk("badframe in sys_rt_sigreturn, regs=%p uc=%p &uc->uc_mcontext=%p\n", 351 regs, uc, &uc->uc_mcontext); 352 #endif 353 force_sig(SIGSEGV, current); 354 return 0; 355 } 356 357 static int setup_rt_frame(int signr, struct k_sigaction *ka, siginfo_t *info, 358 sigset_t *set, struct pt_regs *regs) 359 { 360 /* Handler is *really* a pointer to the function descriptor for 361 * the signal routine. The first entry in the function 362 * descriptor is the entry address of signal and the second 363 * entry is the TOC value we need to use. 364 */ 365 func_descr_t __user *funct_desc_ptr; 366 struct rt_sigframe __user *frame; 367 unsigned long newsp = 0; 368 long err = 0; 369 370 frame = get_sigframe(ka, regs, sizeof(*frame)); 371 372 if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame))) 373 goto badframe; 374 375 err |= __put_user(&frame->info, &frame->pinfo); 376 err |= __put_user(&frame->uc, &frame->puc); 377 err |= copy_siginfo_to_user(&frame->info, info); 378 if (err) 379 goto badframe; 380 381 /* Create the ucontext. */ 382 err |= __put_user(0, &frame->uc.uc_flags); 383 err |= __put_user(0, &frame->uc.uc_link); 384 err |= __put_user(current->sas_ss_sp, &frame->uc.uc_stack.ss_sp); 385 err |= __put_user(sas_ss_flags(regs->gpr[1]), 386 &frame->uc.uc_stack.ss_flags); 387 err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size); 388 err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, signr, NULL, 389 (unsigned long)ka->sa.sa_handler); 390 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)); 391 if (err) 392 goto badframe; 393 394 /* Make sure signal handler doesn't get spurious FP exceptions */ 395 current->thread.fpscr.val = 0; 396 397 /* Set up to return from userspace. */ 398 if (vdso64_rt_sigtramp && current->thread.vdso_base) { 399 regs->link = current->thread.vdso_base + vdso64_rt_sigtramp; 400 } else { 401 err |= setup_trampoline(__NR_rt_sigreturn, &frame->tramp[0]); 402 if (err) 403 goto badframe; 404 regs->link = (unsigned long) &frame->tramp[0]; 405 } 406 funct_desc_ptr = (func_descr_t __user *) ka->sa.sa_handler; 407 408 /* Allocate a dummy caller frame for the signal handler. */ 409 newsp = (unsigned long)frame - __SIGNAL_FRAMESIZE; 410 err |= put_user(regs->gpr[1], (unsigned long __user *)newsp); 411 412 /* Set up "regs" so we "return" to the signal handler. */ 413 err |= get_user(regs->nip, &funct_desc_ptr->entry); 414 regs->gpr[1] = newsp; 415 err |= get_user(regs->gpr[2], &funct_desc_ptr->toc); 416 regs->gpr[3] = signr; 417 regs->result = 0; 418 if (ka->sa.sa_flags & SA_SIGINFO) { 419 err |= get_user(regs->gpr[4], (unsigned long __user *)&frame->pinfo); 420 err |= get_user(regs->gpr[5], (unsigned long __user *)&frame->puc); 421 regs->gpr[6] = (unsigned long) frame; 422 } else { 423 regs->gpr[4] = (unsigned long)&frame->uc.uc_mcontext; 424 } 425 if (err) 426 goto badframe; 427 428 return 1; 429 430 badframe: 431 #if DEBUG_SIG 432 printk("badframe in setup_rt_frame, regs=%p frame=%p newsp=%lx\n", 433 regs, frame, newsp); 434 #endif 435 force_sigsegv(signr, current); 436 return 0; 437 } 438 439 440 /* 441 * OK, we're invoking a handler 442 */ 443 static int handle_signal(unsigned long sig, struct k_sigaction *ka, 444 siginfo_t *info, sigset_t *oldset, struct pt_regs *regs) 445 { 446 int ret; 447 448 /* Set up Signal Frame */ 449 ret = setup_rt_frame(sig, ka, info, oldset, regs); 450 451 if (ret) { 452 spin_lock_irq(¤t->sighand->siglock); 453 sigorsets(¤t->blocked, ¤t->blocked, &ka->sa.sa_mask); 454 if (!(ka->sa.sa_flags & SA_NODEFER)) 455 sigaddset(¤t->blocked,sig); 456 recalc_sigpending(); 457 spin_unlock_irq(¤t->sighand->siglock); 458 } 459 460 return ret; 461 } 462 463 static inline void syscall_restart(struct pt_regs *regs, struct k_sigaction *ka) 464 { 465 switch ((int)regs->result) { 466 case -ERESTART_RESTARTBLOCK: 467 case -ERESTARTNOHAND: 468 /* ERESTARTNOHAND means that the syscall should only be 469 * restarted if there was no handler for the signal, and since 470 * we only get here if there is a handler, we dont restart. 471 */ 472 regs->result = -EINTR; 473 regs->gpr[3] = EINTR; 474 regs->ccr |= 0x10000000; 475 break; 476 case -ERESTARTSYS: 477 /* ERESTARTSYS means to restart the syscall if there is no 478 * handler or the handler was registered with SA_RESTART 479 */ 480 if (!(ka->sa.sa_flags & SA_RESTART)) { 481 regs->result = -EINTR; 482 regs->gpr[3] = EINTR; 483 regs->ccr |= 0x10000000; 484 break; 485 } 486 /* fallthrough */ 487 case -ERESTARTNOINTR: 488 /* ERESTARTNOINTR means that the syscall should be 489 * called again after the signal handler returns. 490 */ 491 regs->gpr[3] = regs->orig_gpr3; 492 regs->nip -= 4; 493 regs->result = 0; 494 break; 495 } 496 } 497 498 /* 499 * Note that 'init' is a special process: it doesn't get signals it doesn't 500 * want to handle. Thus you cannot kill init even with a SIGKILL even by 501 * mistake. 502 */ 503 int do_signal(sigset_t *oldset, struct pt_regs *regs) 504 { 505 siginfo_t info; 506 int signr; 507 struct k_sigaction ka; 508 509 /* 510 * If the current thread is 32 bit - invoke the 511 * 32 bit signal handling code 512 */ 513 if (test_thread_flag(TIF_32BIT)) 514 return do_signal32(oldset, regs); 515 516 if (test_thread_flag(TIF_RESTORE_SIGMASK)) 517 oldset = ¤t->saved_sigmask; 518 else if (!oldset) 519 oldset = ¤t->blocked; 520 521 signr = get_signal_to_deliver(&info, &ka, regs, NULL); 522 if (signr > 0) { 523 int ret; 524 525 /* Whee! Actually deliver the signal. */ 526 if (TRAP(regs) == 0x0C00) 527 syscall_restart(regs, &ka); 528 529 /* 530 * Reenable the DABR before delivering the signal to 531 * user space. The DABR will have been cleared if it 532 * triggered inside the kernel. 533 */ 534 if (current->thread.dabr) 535 set_dabr(current->thread.dabr); 536 537 ret = handle_signal(signr, &ka, &info, oldset, regs); 538 539 /* If a signal was successfully delivered, the saved sigmask is in 540 its frame, and we can clear the TIF_RESTORE_SIGMASK flag */ 541 if (ret && test_thread_flag(TIF_RESTORE_SIGMASK)) 542 clear_thread_flag(TIF_RESTORE_SIGMASK); 543 544 return ret; 545 } 546 547 if (TRAP(regs) == 0x0C00) { /* System Call! */ 548 if ((int)regs->result == -ERESTARTNOHAND || 549 (int)regs->result == -ERESTARTSYS || 550 (int)regs->result == -ERESTARTNOINTR) { 551 regs->gpr[3] = regs->orig_gpr3; 552 regs->nip -= 4; /* Back up & retry system call */ 553 regs->result = 0; 554 } else if ((int)regs->result == -ERESTART_RESTARTBLOCK) { 555 regs->gpr[0] = __NR_restart_syscall; 556 regs->nip -= 4; 557 regs->result = 0; 558 } 559 } 560 /* No signal to deliver -- put the saved sigmask back */ 561 if (test_thread_flag(TIF_RESTORE_SIGMASK)) { 562 clear_thread_flag(TIF_RESTORE_SIGMASK); 563 sigprocmask(SIG_SETMASK, ¤t->saved_sigmask, NULL); 564 } 565 566 return 0; 567 } 568 EXPORT_SYMBOL(do_signal); 569