1 /* 2 * Copyright (C) 1991, 1992 Linus Torvalds 3 * Copyright (C) 2000, 2001, 2002 Andi Kleen SuSE Labs 4 * 5 * 1997-11-28 Modified for POSIX.1b signals by Richard Henderson 6 * 2000-06-20 Pentium III FXSR, SSE support by Gareth Hughes 7 * 2000-2002 x86-64 support by Andi Kleen 8 */ 9 10 #include <linux/sched.h> 11 #include <linux/mm.h> 12 #include <linux/smp.h> 13 #include <linux/kernel.h> 14 #include <linux/signal.h> 15 #include <linux/errno.h> 16 #include <linux/wait.h> 17 #include <linux/ptrace.h> 18 #include <linux/unistd.h> 19 #include <linux/stddef.h> 20 #include <linux/personality.h> 21 #include <linux/compiler.h> 22 #include <asm/ucontext.h> 23 #include <asm/uaccess.h> 24 #include <asm/i387.h> 25 #include <asm/proto.h> 26 #include <asm/ia32_unistd.h> 27 #include <asm/mce.h> 28 29 /* #define DEBUG_SIG 1 */ 30 31 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP))) 32 33 int ia32_setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info, 34 sigset_t *set, struct pt_regs * regs); 35 int ia32_setup_frame(int sig, struct k_sigaction *ka, 36 sigset_t *set, struct pt_regs * regs); 37 38 asmlinkage long 39 sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss, 40 struct pt_regs *regs) 41 { 42 return do_sigaltstack(uss, uoss, regs->sp); 43 } 44 45 46 /* 47 * Do a signal return; undo the signal stack. 48 */ 49 50 struct rt_sigframe 51 { 52 char __user *pretcode; 53 struct ucontext uc; 54 struct siginfo info; 55 }; 56 57 static int 58 restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc, unsigned long *prax) 59 { 60 unsigned int err = 0; 61 62 /* Always make any pending restarted system calls return -EINTR */ 63 current_thread_info()->restart_block.fn = do_no_restart_syscall; 64 65 #define COPY(x) err |= __get_user(regs->x, &sc->x) 66 67 COPY(di); COPY(si); COPY(bp); COPY(sp); COPY(bx); 68 COPY(dx); COPY(cx); COPY(ip); 69 COPY(r8); 70 COPY(r9); 71 COPY(r10); 72 COPY(r11); 73 COPY(r12); 74 COPY(r13); 75 COPY(r14); 76 COPY(r15); 77 78 /* Kernel saves and restores only the CS segment register on signals, 79 * which is the bare minimum needed to allow mixed 32/64-bit code. 80 * App's signal handler can save/restore other segments if needed. */ 81 { 82 unsigned cs; 83 err |= __get_user(cs, &sc->cs); 84 regs->cs = cs | 3; /* Force into user mode */ 85 } 86 87 { 88 unsigned int tmpflags; 89 err |= __get_user(tmpflags, &sc->flags); 90 regs->flags = (regs->flags & ~0x40DD5) | (tmpflags & 0x40DD5); 91 regs->orig_ax = -1; /* disable syscall checks */ 92 } 93 94 { 95 struct _fpstate __user * buf; 96 err |= __get_user(buf, &sc->fpstate); 97 98 if (buf) { 99 if (!access_ok(VERIFY_READ, buf, sizeof(*buf))) 100 goto badframe; 101 err |= restore_i387(buf); 102 } else { 103 struct task_struct *me = current; 104 if (used_math()) { 105 clear_fpu(me); 106 clear_used_math(); 107 } 108 } 109 } 110 111 err |= __get_user(*prax, &sc->ax); 112 return err; 113 114 badframe: 115 return 1; 116 } 117 118 asmlinkage long sys_rt_sigreturn(struct pt_regs *regs) 119 { 120 struct rt_sigframe __user *frame; 121 sigset_t set; 122 unsigned long ax; 123 124 frame = (struct rt_sigframe __user *)(regs->sp - 8); 125 if (!access_ok(VERIFY_READ, frame, sizeof(*frame))) { 126 goto badframe; 127 } 128 if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set))) { 129 goto badframe; 130 } 131 132 sigdelsetmask(&set, ~_BLOCKABLE); 133 spin_lock_irq(¤t->sighand->siglock); 134 current->blocked = set; 135 recalc_sigpending(); 136 spin_unlock_irq(¤t->sighand->siglock); 137 138 if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &ax)) 139 goto badframe; 140 141 #ifdef DEBUG_SIG 142 printk("%d sigreturn ip:%lx sp:%lx frame:%p ax:%lx\n",current->pid,regs->ip,regs->sp,frame,ax); 143 #endif 144 145 if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->sp) == -EFAULT) 146 goto badframe; 147 148 return ax; 149 150 badframe: 151 signal_fault(regs,frame,"sigreturn"); 152 return 0; 153 } 154 155 /* 156 * Set up a signal frame. 157 */ 158 159 static inline int 160 setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs, unsigned long mask, struct task_struct *me) 161 { 162 int err = 0; 163 164 err |= __put_user(regs->cs, &sc->cs); 165 err |= __put_user(0, &sc->gs); 166 err |= __put_user(0, &sc->fs); 167 168 err |= __put_user(regs->di, &sc->di); 169 err |= __put_user(regs->si, &sc->si); 170 err |= __put_user(regs->bp, &sc->bp); 171 err |= __put_user(regs->sp, &sc->sp); 172 err |= __put_user(regs->bx, &sc->bx); 173 err |= __put_user(regs->dx, &sc->dx); 174 err |= __put_user(regs->cx, &sc->cx); 175 err |= __put_user(regs->ax, &sc->ax); 176 err |= __put_user(regs->r8, &sc->r8); 177 err |= __put_user(regs->r9, &sc->r9); 178 err |= __put_user(regs->r10, &sc->r10); 179 err |= __put_user(regs->r11, &sc->r11); 180 err |= __put_user(regs->r12, &sc->r12); 181 err |= __put_user(regs->r13, &sc->r13); 182 err |= __put_user(regs->r14, &sc->r14); 183 err |= __put_user(regs->r15, &sc->r15); 184 err |= __put_user(me->thread.trap_no, &sc->trapno); 185 err |= __put_user(me->thread.error_code, &sc->err); 186 err |= __put_user(regs->ip, &sc->ip); 187 err |= __put_user(regs->flags, &sc->flags); 188 err |= __put_user(mask, &sc->oldmask); 189 err |= __put_user(me->thread.cr2, &sc->cr2); 190 191 return err; 192 } 193 194 /* 195 * Determine which stack to use.. 196 */ 197 198 static void __user * 199 get_stack(struct k_sigaction *ka, struct pt_regs *regs, unsigned long size) 200 { 201 unsigned long sp; 202 203 /* Default to using normal stack - redzone*/ 204 sp = regs->sp - 128; 205 206 /* This is the X/Open sanctioned signal stack switching. */ 207 if (ka->sa.sa_flags & SA_ONSTACK) { 208 if (sas_ss_flags(sp) == 0) 209 sp = current->sas_ss_sp + current->sas_ss_size; 210 } 211 212 return (void __user *)round_down(sp - size, 16); 213 } 214 215 static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info, 216 sigset_t *set, struct pt_regs * regs) 217 { 218 struct rt_sigframe __user *frame; 219 struct _fpstate __user *fp = NULL; 220 int err = 0; 221 struct task_struct *me = current; 222 223 if (used_math()) { 224 fp = get_stack(ka, regs, sizeof(struct _fpstate)); 225 frame = (void __user *)round_down( 226 (unsigned long)fp - sizeof(struct rt_sigframe), 16) - 8; 227 228 if (!access_ok(VERIFY_WRITE, fp, sizeof(struct _fpstate))) 229 goto give_sigsegv; 230 231 if (save_i387(fp) < 0) 232 err |= -1; 233 } else 234 frame = get_stack(ka, regs, sizeof(struct rt_sigframe)) - 8; 235 236 if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame))) 237 goto give_sigsegv; 238 239 if (ka->sa.sa_flags & SA_SIGINFO) { 240 err |= copy_siginfo_to_user(&frame->info, info); 241 if (err) 242 goto give_sigsegv; 243 } 244 245 /* Create the ucontext. */ 246 err |= __put_user(0, &frame->uc.uc_flags); 247 err |= __put_user(0, &frame->uc.uc_link); 248 err |= __put_user(me->sas_ss_sp, &frame->uc.uc_stack.ss_sp); 249 err |= __put_user(sas_ss_flags(regs->sp), 250 &frame->uc.uc_stack.ss_flags); 251 err |= __put_user(me->sas_ss_size, &frame->uc.uc_stack.ss_size); 252 err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, set->sig[0], me); 253 err |= __put_user(fp, &frame->uc.uc_mcontext.fpstate); 254 if (sizeof(*set) == 16) { 255 __put_user(set->sig[0], &frame->uc.uc_sigmask.sig[0]); 256 __put_user(set->sig[1], &frame->uc.uc_sigmask.sig[1]); 257 } else 258 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)); 259 260 /* Set up to return from userspace. If provided, use a stub 261 already in userspace. */ 262 /* x86-64 should always use SA_RESTORER. */ 263 if (ka->sa.sa_flags & SA_RESTORER) { 264 err |= __put_user(ka->sa.sa_restorer, &frame->pretcode); 265 } else { 266 /* could use a vstub here */ 267 goto give_sigsegv; 268 } 269 270 if (err) 271 goto give_sigsegv; 272 273 #ifdef DEBUG_SIG 274 printk("%d old ip %lx old sp %lx old ax %lx\n", current->pid,regs->ip,regs->sp,regs->ax); 275 #endif 276 277 /* Set up registers for signal handler */ 278 regs->di = sig; 279 /* In case the signal handler was declared without prototypes */ 280 regs->ax = 0; 281 282 /* This also works for non SA_SIGINFO handlers because they expect the 283 next argument after the signal number on the stack. */ 284 regs->si = (unsigned long)&frame->info; 285 regs->dx = (unsigned long)&frame->uc; 286 regs->ip = (unsigned long) ka->sa.sa_handler; 287 288 regs->sp = (unsigned long)frame; 289 290 /* Set up the CS register to run signal handlers in 64-bit mode, 291 even if the handler happens to be interrupting 32-bit code. */ 292 regs->cs = __USER_CS; 293 294 /* This, by contrast, has nothing to do with segment registers - 295 see include/asm-x86_64/uaccess.h for details. */ 296 set_fs(USER_DS); 297 298 regs->flags &= ~X86_EFLAGS_TF; 299 if (test_thread_flag(TIF_SINGLESTEP)) 300 ptrace_notify(SIGTRAP); 301 #ifdef DEBUG_SIG 302 printk("SIG deliver (%s:%d): sp=%p pc=%lx ra=%p\n", 303 current->comm, current->pid, frame, regs->ip, frame->pretcode); 304 #endif 305 306 return 0; 307 308 give_sigsegv: 309 force_sigsegv(sig, current); 310 return -EFAULT; 311 } 312 313 /* 314 * OK, we're invoking a handler 315 */ 316 317 static int 318 handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka, 319 sigset_t *oldset, struct pt_regs *regs) 320 { 321 int ret; 322 323 #ifdef DEBUG_SIG 324 printk("handle_signal pid:%d sig:%lu ip:%lx sp:%lx regs=%p\n", 325 current->pid, sig, 326 regs->ip, regs->sp, regs); 327 #endif 328 329 /* Are we from a system call? */ 330 if ((long)regs->orig_ax >= 0) { 331 /* If so, check system call restarting.. */ 332 switch (regs->ax) { 333 case -ERESTART_RESTARTBLOCK: 334 case -ERESTARTNOHAND: 335 regs->ax = -EINTR; 336 break; 337 338 case -ERESTARTSYS: 339 if (!(ka->sa.sa_flags & SA_RESTART)) { 340 regs->ax = -EINTR; 341 break; 342 } 343 /* fallthrough */ 344 case -ERESTARTNOINTR: 345 regs->ax = regs->orig_ax; 346 regs->ip -= 2; 347 break; 348 } 349 } 350 351 /* 352 * If TF is set due to a debugger (TIF_FORCED_TF), clear the TF 353 * flag so that register information in the sigcontext is correct. 354 */ 355 if (unlikely(regs->flags & X86_EFLAGS_TF) && 356 likely(test_and_clear_thread_flag(TIF_FORCED_TF))) 357 regs->flags &= ~X86_EFLAGS_TF; 358 359 #ifdef CONFIG_IA32_EMULATION 360 if (test_thread_flag(TIF_IA32)) { 361 if (ka->sa.sa_flags & SA_SIGINFO) 362 ret = ia32_setup_rt_frame(sig, ka, info, oldset, regs); 363 else 364 ret = ia32_setup_frame(sig, ka, oldset, regs); 365 } else 366 #endif 367 ret = setup_rt_frame(sig, ka, info, oldset, regs); 368 369 if (ret == 0) { 370 spin_lock_irq(¤t->sighand->siglock); 371 sigorsets(¤t->blocked,¤t->blocked,&ka->sa.sa_mask); 372 if (!(ka->sa.sa_flags & SA_NODEFER)) 373 sigaddset(¤t->blocked,sig); 374 recalc_sigpending(); 375 spin_unlock_irq(¤t->sighand->siglock); 376 } 377 378 return ret; 379 } 380 381 /* 382 * Note that 'init' is a special process: it doesn't get signals it doesn't 383 * want to handle. Thus you cannot kill init even with a SIGKILL even by 384 * mistake. 385 */ 386 static void do_signal(struct pt_regs *regs) 387 { 388 struct k_sigaction ka; 389 siginfo_t info; 390 int signr; 391 sigset_t *oldset; 392 393 /* 394 * We want the common case to go fast, which 395 * is why we may in certain cases get here from 396 * kernel mode. Just return without doing anything 397 * if so. 398 */ 399 if (!user_mode(regs)) 400 return; 401 402 if (test_thread_flag(TIF_RESTORE_SIGMASK)) 403 oldset = ¤t->saved_sigmask; 404 else 405 oldset = ¤t->blocked; 406 407 signr = get_signal_to_deliver(&info, &ka, regs, NULL); 408 if (signr > 0) { 409 /* Re-enable any watchpoints before delivering the 410 * signal to user space. The processor register will 411 * have been cleared if the watchpoint triggered 412 * inside the kernel. 413 */ 414 if (current->thread.debugreg7) 415 set_debugreg(current->thread.debugreg7, 7); 416 417 /* Whee! Actually deliver the signal. */ 418 if (handle_signal(signr, &info, &ka, oldset, regs) == 0) { 419 /* a signal was successfully delivered; the saved 420 * sigmask will have been stored in the signal frame, 421 * and will be restored by sigreturn, so we can simply 422 * clear the TIF_RESTORE_SIGMASK flag */ 423 clear_thread_flag(TIF_RESTORE_SIGMASK); 424 } 425 return; 426 } 427 428 /* Did we come from a system call? */ 429 if ((long)regs->orig_ax >= 0) { 430 /* Restart the system call - no handlers present */ 431 long res = regs->ax; 432 switch (res) { 433 case -ERESTARTNOHAND: 434 case -ERESTARTSYS: 435 case -ERESTARTNOINTR: 436 regs->ax = regs->orig_ax; 437 regs->ip -= 2; 438 break; 439 case -ERESTART_RESTARTBLOCK: 440 regs->ax = test_thread_flag(TIF_IA32) ? 441 __NR_ia32_restart_syscall : 442 __NR_restart_syscall; 443 regs->ip -= 2; 444 break; 445 } 446 } 447 448 /* if there's no signal to deliver, we just put the saved sigmask 449 back. */ 450 if (test_thread_flag(TIF_RESTORE_SIGMASK)) { 451 clear_thread_flag(TIF_RESTORE_SIGMASK); 452 sigprocmask(SIG_SETMASK, ¤t->saved_sigmask, NULL); 453 } 454 } 455 456 void 457 do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags) 458 { 459 #ifdef DEBUG_SIG 460 printk("do_notify_resume flags:%x ip:%lx sp:%lx caller:%p pending:%x\n", 461 thread_info_flags, regs->ip, regs->sp, __builtin_return_address(0),signal_pending(current)); 462 #endif 463 464 /* Pending single-step? */ 465 if (thread_info_flags & _TIF_SINGLESTEP) { 466 regs->flags |= X86_EFLAGS_TF; 467 clear_thread_flag(TIF_SINGLESTEP); 468 } 469 470 #ifdef CONFIG_X86_MCE 471 /* notify userspace of pending MCEs */ 472 if (thread_info_flags & _TIF_MCE_NOTIFY) 473 mce_notify_user(); 474 #endif /* CONFIG_X86_MCE */ 475 476 /* deal with pending signal delivery */ 477 if (thread_info_flags & (_TIF_SIGPENDING|_TIF_RESTORE_SIGMASK)) 478 do_signal(regs); 479 480 if (thread_info_flags & _TIF_HRTICK_RESCHED) 481 hrtick_resched(); 482 } 483 484 void signal_fault(struct pt_regs *regs, void __user *frame, char *where) 485 { 486 struct task_struct *me = current; 487 if (show_unhandled_signals && printk_ratelimit()) { 488 printk("%s[%d] bad frame in %s frame:%p ip:%lx sp:%lx orax:%lx", 489 me->comm,me->pid,where,frame,regs->ip,regs->sp,regs->orig_ax); 490 print_vma_addr(" in ", regs->ip); 491 printk("\n"); 492 } 493 494 force_sig(SIGSEGV, me); 495 } 496