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/kernel.h> 19#include <linux/signal.h> 20#include <linux/errno.h> 21#include <linux/wait.h> 22#include <linux/unistd.h> 23#include <linux/stddef.h> 24#include <linux/elf.h> 25#include <linux/ptrace.h> 26#include <linux/module.h> 27 28#include <asm/sigcontext.h> 29#include <asm/ucontext.h> 30#include <asm/uaccess.h> 31#include <asm/pgtable.h> 32#include <asm/unistd.h> 33#include <asm/cacheflush.h> 34#include <asm/syscalls.h> 35#include <asm/vdso.h> 36 37#define DEBUG_SIG 0 38 39#define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP))) 40 41#define GP_REGS_SIZE min(sizeof(elf_gregset_t), sizeof(struct pt_regs)) 42#define FP_REGS_SIZE sizeof(elf_fpregset_t) 43 44#define TRAMP_TRACEBACK 3 45#define TRAMP_SIZE 6 46 47/* 48 * When we have signals to deliver, we set up on the user stack, 49 * going down from the original stack pointer: 50 * 1) a rt_sigframe struct which contains the ucontext 51 * 2) a gap of __SIGNAL_FRAMESIZE bytes which acts as a dummy caller 52 * frame for the signal handler. 53 */ 54 55struct rt_sigframe { 56 /* sys_rt_sigreturn requires the ucontext be the first field */ 57 struct ucontext uc; 58 unsigned long _unused[2]; 59 unsigned int tramp[TRAMP_SIZE]; 60 struct siginfo __user *pinfo; 61 void __user *puc; 62 struct siginfo info; 63 /* 64 bit ABI allows for 288 bytes below sp before decrementing it. */ 64 char abigap[288]; 65} __attribute__ ((aligned (16))); 66 67long sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss, unsigned long r5, 68 unsigned long r6, unsigned long r7, unsigned long r8, 69 struct pt_regs *regs) 70{ 71 return do_sigaltstack(uss, uoss, regs->gpr[1]); 72} 73 74 75/* 76 * Set up the sigcontext for the signal frame. 77 */ 78 79static long setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs, 80 int signr, sigset_t *set, unsigned long handler) 81{ 82 /* When CONFIG_ALTIVEC is set, we _always_ setup v_regs even if the 83 * process never used altivec yet (MSR_VEC is zero in pt_regs of 84 * the context). This is very important because we must ensure we 85 * don't lose the VRSAVE content that may have been set prior to 86 * the process doing its first vector operation 87 * Userland shall check AT_HWCAP to know wether it can rely on the 88 * v_regs pointer or not 89 */ 90#ifdef CONFIG_ALTIVEC 91 elf_vrreg_t __user *v_regs = (elf_vrreg_t __user *)(((unsigned long)sc->vmx_reserve + 15) & ~0xful); 92#endif 93 long err = 0; 94 95 flush_fp_to_thread(current); 96 97#ifdef CONFIG_ALTIVEC 98 err |= __put_user(v_regs, &sc->v_regs); 99 100 /* save altivec registers */ 101 if (current->thread.used_vr) { 102 flush_altivec_to_thread(current); 103 /* Copy 33 vec registers (vr0..31 and vscr) to the stack */ 104 err |= __copy_to_user(v_regs, current->thread.vr, 33 * sizeof(vector128)); 105 /* set MSR_VEC in the MSR value in the frame to indicate that sc->v_reg) 106 * contains valid data. 107 */ 108 regs->msr |= MSR_VEC; 109 } 110 /* We always copy to/from vrsave, it's 0 if we don't have or don't 111 * use altivec. 112 */ 113 err |= __put_user(current->thread.vrsave, (u32 __user *)&v_regs[33]); 114#else /* CONFIG_ALTIVEC */ 115 err |= __put_user(0, &sc->v_regs); 116#endif /* CONFIG_ALTIVEC */ 117 err |= __put_user(&sc->gp_regs, &sc->regs); 118 WARN_ON(!FULL_REGS(regs)); 119 err |= __copy_to_user(&sc->gp_regs, regs, GP_REGS_SIZE); 120 err |= __copy_to_user(&sc->fp_regs, ¤t->thread.fpr, FP_REGS_SIZE); 121 err |= __put_user(signr, &sc->signal); 122 err |= __put_user(handler, &sc->handler); 123 if (set != NULL) 124 err |= __put_user(set->sig[0], &sc->oldmask); 125 126 return err; 127} 128 129/* 130 * Restore the sigcontext from the signal frame. 131 */ 132 133static long restore_sigcontext(struct pt_regs *regs, sigset_t *set, int sig, 134 struct sigcontext __user *sc) 135{ 136#ifdef CONFIG_ALTIVEC 137 elf_vrreg_t __user *v_regs; 138#endif 139 unsigned long err = 0; 140 unsigned long save_r13 = 0; 141 elf_greg_t *gregs = (elf_greg_t *)regs; 142 unsigned long msr; 143 int i; 144 145 /* If this is not a signal return, we preserve the TLS in r13 */ 146 if (!sig) 147 save_r13 = regs->gpr[13]; 148 149 /* copy everything before MSR */ 150 err |= __copy_from_user(regs, &sc->gp_regs, 151 PT_MSR*sizeof(unsigned long)); 152 153 /* get MSR separately, transfer the LE bit if doing signal return */ 154 err |= __get_user(msr, &sc->gp_regs[PT_MSR]); 155 if (sig) 156 regs->msr = (regs->msr & ~MSR_LE) | (msr & MSR_LE); 157 158 /* skip 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 /* 180 * Force reload of FP/VEC. 181 * This has to be done before copying stuff into current->thread.fpr/vr 182 * for the reasons explained in the previous comment. 183 */ 184 regs->msr &= ~(MSR_FP | MSR_FE0 | MSR_FE1 | MSR_VEC); 185 186 err |= __copy_from_user(¤t->thread.fpr, &sc->fp_regs, FP_REGS_SIZE); 187 188#ifdef CONFIG_ALTIVEC 189 err |= __get_user(v_regs, &sc->v_regs); 190 if (err) 191 return err; 192 if (v_regs && !access_ok(VERIFY_READ, v_regs, 34 * sizeof(vector128))) 193 return -EFAULT; 194 /* Copy 33 vec registers (vr0..31 and vscr) from the stack */ 195 if (v_regs != 0 && (msr & MSR_VEC) != 0) 196 err |= __copy_from_user(current->thread.vr, v_regs, 197 33 * sizeof(vector128)); 198 else if (current->thread.used_vr) 199 memset(current->thread.vr, 0, 33 * sizeof(vector128)); 200 /* Always get VRSAVE back */ 201 if (v_regs != 0) 202 err |= __get_user(current->thread.vrsave, (u32 __user *)&v_regs[33]); 203 else 204 current->thread.vrsave = 0; 205#endif /* CONFIG_ALTIVEC */ 206 207 return err; 208} 209 210/* 211 * Allocate space for the signal frame 212 */ 213static inline void __user * get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, 214 size_t frame_size) 215{ 216 unsigned long newsp; 217 218 /* Default to using normal stack */ 219 newsp = regs->gpr[1]; 220 221 if ((ka->sa.sa_flags & SA_ONSTACK) && current->sas_ss_size) { 222 if (! on_sig_stack(regs->gpr[1])) 223 newsp = (current->sas_ss_sp + current->sas_ss_size); 224 } 225 226 return (void __user *)((newsp - frame_size) & -16ul); 227} 228 229/* 230 * Setup the trampoline code on the stack 231 */ 232static long setup_trampoline(unsigned int syscall, unsigned int __user *tramp) 233{ 234 int i; 235 long err = 0; 236 237 /* addi r1, r1, __SIGNAL_FRAMESIZE # Pop the dummy stackframe */ 238 err |= __put_user(0x38210000UL | (__SIGNAL_FRAMESIZE & 0xffff), &tramp[0]); 239 /* li r0, __NR_[rt_]sigreturn| */ 240 err |= __put_user(0x38000000UL | (syscall & 0xffff), &tramp[1]); 241 /* sc */ 242 err |= __put_user(0x44000002UL, &tramp[2]); 243 244 /* Minimal traceback info */ 245 for (i=TRAMP_TRACEBACK; i < TRAMP_SIZE ;i++) 246 err |= __put_user(0, &tramp[i]); 247 248 if (!err) 249 flush_icache_range((unsigned long) &tramp[0], 250 (unsigned long) &tramp[TRAMP_SIZE]); 251 252 return err; 253} 254 255/* 256 * Restore the user process's signal mask (also used by signal32.c) 257 */ 258void restore_sigmask(sigset_t *set) 259{ 260 sigdelsetmask(set, ~_BLOCKABLE); 261 spin_lock_irq(¤t->sighand->siglock); 262 current->blocked = *set; 263 recalc_sigpending(); 264 spin_unlock_irq(¤t->sighand->siglock); 265} 266 267 268/* 269 * Handle {get,set,swap}_context operations 270 */ 271int sys_swapcontext(struct ucontext __user *old_ctx, 272 struct ucontext __user *new_ctx, 273 long ctx_size, long r6, long r7, long r8, struct pt_regs *regs) 274{ 275 unsigned char tmp; 276 sigset_t set; 277 278 /* Context size is for future use. Right now, we only make sure 279 * we are passed something we understand 280 */ 281 if (ctx_size < sizeof(struct ucontext)) 282 return -EINVAL; 283 284 if (old_ctx != NULL) { 285 if (!access_ok(VERIFY_WRITE, old_ctx, sizeof(*old_ctx)) 286 || setup_sigcontext(&old_ctx->uc_mcontext, regs, 0, NULL, 0) 287 || __copy_to_user(&old_ctx->uc_sigmask, 288 ¤t->blocked, sizeof(sigset_t))) 289 return -EFAULT; 290 } 291 if (new_ctx == NULL) 292 return 0; 293 if (!access_ok(VERIFY_READ, new_ctx, sizeof(*new_ctx)) 294 || __get_user(tmp, (u8 __user *) new_ctx) 295 || __get_user(tmp, (u8 __user *) (new_ctx + 1) - 1)) 296 return -EFAULT; 297 298 /* 299 * If we get a fault copying the context into the kernel's 300 * image of the user's registers, we can't just return -EFAULT 301 * because the user's registers will be corrupted. For instance 302 * the NIP value may have been updated but not some of the 303 * other registers. Given that we have done the access_ok 304 * and successfully read the first and last bytes of the region 305 * above, this should only happen in an out-of-memory situation 306 * or if another thread unmaps the region containing the context. 307 * We kill the task with a SIGSEGV in this situation. 308 */ 309 310 if (__copy_from_user(&set, &new_ctx->uc_sigmask, sizeof(set))) 311 do_exit(SIGSEGV); 312 restore_sigmask(&set); 313 if (restore_sigcontext(regs, NULL, 0, &new_ctx->uc_mcontext)) 314 do_exit(SIGSEGV); 315 316 /* This returns like rt_sigreturn */ 317 set_thread_flag(TIF_RESTOREALL); 318 return 0; 319} 320 321 322/* 323 * Do a signal return; undo the signal stack. 324 */ 325 326int sys_rt_sigreturn(unsigned long r3, unsigned long r4, unsigned long r5, 327 unsigned long r6, unsigned long r7, unsigned long r8, 328 struct pt_regs *regs) 329{ 330 struct ucontext __user *uc = (struct ucontext __user *)regs->gpr[1]; 331 sigset_t set; 332 333 /* Always make any pending restarted system calls return -EINTR */ 334 current_thread_info()->restart_block.fn = do_no_restart_syscall; 335 336 if (!access_ok(VERIFY_READ, uc, sizeof(*uc))) 337 goto badframe; 338 339 if (__copy_from_user(&set, &uc->uc_sigmask, sizeof(set))) 340 goto badframe; 341 restore_sigmask(&set); 342 if (restore_sigcontext(regs, NULL, 1, &uc->uc_mcontext)) 343 goto badframe; 344 345 /* do_sigaltstack expects a __user pointer and won't modify 346 * what's in there anyway 347 */ 348 do_sigaltstack(&uc->uc_stack, NULL, regs->gpr[1]); 349 350 set_thread_flag(TIF_RESTOREALL); 351 return 0; 352 353badframe: 354#if DEBUG_SIG 355 printk("badframe in sys_rt_sigreturn, regs=%p uc=%p &uc->uc_mcontext=%p\n", 356 regs, uc, &uc->uc_mcontext); 357#endif 358 force_sig(SIGSEGV, current); 359 return 0; 360} 361 362static int setup_rt_frame(int signr, struct k_sigaction *ka, siginfo_t *info, 363 sigset_t *set, struct pt_regs *regs) 364{ 365 /* Handler is *really* a pointer to the function descriptor for 366 * the signal routine. The first entry in the function 367 * descriptor is the entry address of signal and the second 368 * entry is the TOC value we need to use. 369 */ 370 func_descr_t __user *funct_desc_ptr; 371 struct rt_sigframe __user *frame; 372 unsigned long newsp = 0; 373 long err = 0; 374 375 frame = get_sigframe(ka, regs, sizeof(*frame)); 376 377 if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame))) 378 goto badframe; 379 380 err |= __put_user(&frame->info, &frame->pinfo); 381 err |= __put_user(&frame->uc, &frame->puc); 382 err |= copy_siginfo_to_user(&frame->info, info); 383 if (err) 384 goto badframe; 385 386 /* Create the ucontext. */ 387 err |= __put_user(0, &frame->uc.uc_flags); 388 err |= __put_user(0, &frame->uc.uc_link); 389 err |= __put_user(current->sas_ss_sp, &frame->uc.uc_stack.ss_sp); 390 err |= __put_user(sas_ss_flags(regs->gpr[1]), 391 &frame->uc.uc_stack.ss_flags); 392 err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size); 393 err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, signr, NULL, 394 (unsigned long)ka->sa.sa_handler); 395 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)); 396 if (err) 397 goto badframe; 398 399 /* Make sure signal handler doesn't get spurious FP exceptions */ 400 current->thread.fpscr.val = 0; 401 402 /* Set up to return from userspace. */ 403 if (vdso64_rt_sigtramp && current->mm->context.vdso_base) { 404 regs->link = current->mm->context.vdso_base + vdso64_rt_sigtramp; 405 } else { 406 err |= setup_trampoline(__NR_rt_sigreturn, &frame->tramp[0]); 407 if (err) 408 goto badframe; 409 regs->link = (unsigned long) &frame->tramp[0]; 410 } 411 funct_desc_ptr = (func_descr_t __user *) ka->sa.sa_handler; 412 413 /* Allocate a dummy caller frame for the signal handler. */ 414 newsp = (unsigned long)frame - __SIGNAL_FRAMESIZE; 415 err |= put_user(regs->gpr[1], (unsigned long __user *)newsp); 416 417 /* Set up "regs" so we "return" to the signal handler. */ 418 err |= get_user(regs->nip, &funct_desc_ptr->entry); 419 /* enter the signal handler in big-endian mode */ 420 regs->msr &= ~MSR_LE; 421 regs->gpr[1] = newsp; 422 err |= get_user(regs->gpr[2], &funct_desc_ptr->toc); 423 regs->gpr[3] = signr; 424 regs->result = 0; 425 if (ka->sa.sa_flags & SA_SIGINFO) { 426 err |= get_user(regs->gpr[4], (unsigned long __user *)&frame->pinfo); 427 err |= get_user(regs->gpr[5], (unsigned long __user *)&frame->puc); 428 regs->gpr[6] = (unsigned long) frame; 429 } else { 430 regs->gpr[4] = (unsigned long)&frame->uc.uc_mcontext; 431 } 432 if (err) 433 goto badframe; 434 435 return 1; 436 437badframe: 438#if DEBUG_SIG 439 printk("badframe in setup_rt_frame, regs=%p frame=%p newsp=%lx\n", 440 regs, frame, newsp); 441#endif 442 force_sigsegv(signr, current); 443 return 0; 444} 445 446 447/* 448 * OK, we're invoking a handler 449 */ 450static int handle_signal(unsigned long sig, struct k_sigaction *ka, 451 siginfo_t *info, sigset_t *oldset, struct pt_regs *regs) 452{ 453 int ret; 454 455 /* Set up Signal Frame */ 456 ret = setup_rt_frame(sig, ka, info, oldset, regs); 457 458 if (ret) { 459 spin_lock_irq(¤t->sighand->siglock); 460 sigorsets(¤t->blocked, ¤t->blocked, &ka->sa.sa_mask); 461 if (!(ka->sa.sa_flags & SA_NODEFER)) 462 sigaddset(¤t->blocked,sig); 463 recalc_sigpending(); 464 spin_unlock_irq(¤t->sighand->siglock); 465 } 466 467 return ret; 468} 469 470static inline void syscall_restart(struct pt_regs *regs, struct k_sigaction *ka) 471{ 472 switch ((int)regs->result) { 473 case -ERESTART_RESTARTBLOCK: 474 case -ERESTARTNOHAND: 475 /* ERESTARTNOHAND means that the syscall should only be 476 * restarted if there was no handler for the signal, and since 477 * we only get here if there is a handler, we dont restart. 478 */ 479 regs->result = -EINTR; 480 regs->gpr[3] = EINTR; 481 regs->ccr |= 0x10000000; 482 break; 483 case -ERESTARTSYS: 484 /* ERESTARTSYS means to restart the syscall if there is no 485 * handler or the handler was registered with SA_RESTART 486 */ 487 if (!(ka->sa.sa_flags & SA_RESTART)) { 488 regs->result = -EINTR; 489 regs->gpr[3] = EINTR; 490 regs->ccr |= 0x10000000; 491 break; 492 } 493 /* fallthrough */ 494 case -ERESTARTNOINTR: 495 /* ERESTARTNOINTR means that the syscall should be 496 * called again after the signal handler returns. 497 */ 498 regs->gpr[3] = regs->orig_gpr3; 499 regs->nip -= 4; 500 regs->result = 0; 501 break; 502 } 503} 504 505/* 506 * Note that 'init' is a special process: it doesn't get signals it doesn't 507 * want to handle. Thus you cannot kill init even with a SIGKILL even by 508 * mistake. 509 */ 510int do_signal(sigset_t *oldset, struct pt_regs *regs) 511{ 512 siginfo_t info; 513 int signr; 514 struct k_sigaction ka; 515 516 /* 517 * If the current thread is 32 bit - invoke the 518 * 32 bit signal handling code 519 */ 520 if (test_thread_flag(TIF_32BIT)) 521 return do_signal32(oldset, regs); 522 523 if (test_thread_flag(TIF_RESTORE_SIGMASK)) 524 oldset = ¤t->saved_sigmask; 525 else if (!oldset) 526 oldset = ¤t->blocked; 527 528 signr = get_signal_to_deliver(&info, &ka, regs, NULL); 529 if (signr > 0) { 530 int ret; 531 532 /* Whee! Actually deliver the signal. */ 533 if (TRAP(regs) == 0x0C00) 534 syscall_restart(regs, &ka); 535 536 /* 537 * Reenable the DABR before delivering the signal to 538 * user space. The DABR will have been cleared if it 539 * triggered inside the kernel. 540 */ 541 if (current->thread.dabr) 542 set_dabr(current->thread.dabr); 543 544 ret = handle_signal(signr, &ka, &info, oldset, regs); 545 546 /* If a signal was successfully delivered, the saved sigmask is in 547 its frame, and we can clear the TIF_RESTORE_SIGMASK flag */ 548 if (ret && test_thread_flag(TIF_RESTORE_SIGMASK)) 549 clear_thread_flag(TIF_RESTORE_SIGMASK); 550 551 return ret; 552 } 553 554 if (TRAP(regs) == 0x0C00) { /* System Call! */ 555 if ((int)regs->result == -ERESTARTNOHAND || 556 (int)regs->result == -ERESTARTSYS || 557 (int)regs->result == -ERESTARTNOINTR) { 558 regs->gpr[3] = regs->orig_gpr3; 559 regs->nip -= 4; /* Back up & retry system call */ 560 regs->result = 0; 561 } else if ((int)regs->result == -ERESTART_RESTARTBLOCK) { 562 regs->gpr[0] = __NR_restart_syscall; 563 regs->nip -= 4; 564 regs->result = 0; 565 } 566 } 567 /* No signal to deliver -- put the saved sigmask back */ 568 if (test_thread_flag(TIF_RESTORE_SIGMASK)) { 569 clear_thread_flag(TIF_RESTORE_SIGMASK); 570 sigprocmask(SIG_SETMASK, ¤t->saved_sigmask, NULL); 571 } 572 573 return 0; 574} 575EXPORT_SYMBOL(do_signal); 576