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/tracehook.h> 19 #include <linux/unistd.h> 20 #include <linux/stddef.h> 21 #include <linux/personality.h> 22 #include <linux/compiler.h> 23 #include <asm/processor.h> 24 #include <asm/ucontext.h> 25 #include <asm/uaccess.h> 26 #include <asm/i387.h> 27 #include <asm/proto.h> 28 #include <asm/ia32_unistd.h> 29 #include <asm/mce.h> 30 #include <asm/syscall.h> 31 #include <asm/syscalls.h> 32 #include "sigframe.h" 33 34 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP))) 35 36 #define __FIX_EFLAGS (X86_EFLAGS_AC | X86_EFLAGS_OF | \ 37 X86_EFLAGS_DF | X86_EFLAGS_TF | X86_EFLAGS_SF | \ 38 X86_EFLAGS_ZF | X86_EFLAGS_AF | X86_EFLAGS_PF | \ 39 X86_EFLAGS_CF) 40 41 #ifdef CONFIG_X86_32 42 # define FIX_EFLAGS (__FIX_EFLAGS | X86_EFLAGS_RF) 43 #else 44 # define FIX_EFLAGS __FIX_EFLAGS 45 #endif 46 47 int ia32_setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info, 48 sigset_t *set, struct pt_regs * regs); 49 int ia32_setup_frame(int sig, struct k_sigaction *ka, 50 sigset_t *set, struct pt_regs * regs); 51 52 asmlinkage long 53 sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss, 54 struct pt_regs *regs) 55 { 56 return do_sigaltstack(uss, uoss, regs->sp); 57 } 58 59 /* 60 * Signal frame handlers. 61 */ 62 63 static inline int save_i387(struct _fpstate __user *buf) 64 { 65 struct task_struct *tsk = current; 66 int err = 0; 67 68 BUILD_BUG_ON(sizeof(struct user_i387_struct) != 69 sizeof(tsk->thread.xstate->fxsave)); 70 71 if ((unsigned long)buf % 16) 72 printk("save_i387: bad fpstate %p\n", buf); 73 74 if (!used_math()) 75 return 0; 76 clear_used_math(); /* trigger finit */ 77 if (task_thread_info(tsk)->status & TS_USEDFPU) { 78 err = save_i387_checking((struct i387_fxsave_struct __user *) 79 buf); 80 if (err) 81 return err; 82 task_thread_info(tsk)->status &= ~TS_USEDFPU; 83 stts(); 84 } else { 85 if (__copy_to_user(buf, &tsk->thread.xstate->fxsave, 86 sizeof(struct i387_fxsave_struct))) 87 return -1; 88 } 89 return 1; 90 } 91 92 /* 93 * This restores directly out of user space. Exceptions are handled. 94 */ 95 static inline int restore_i387(struct _fpstate __user *buf) 96 { 97 struct task_struct *tsk = current; 98 int err; 99 100 if (!used_math()) { 101 err = init_fpu(tsk); 102 if (err) 103 return err; 104 } 105 106 if (!(task_thread_info(current)->status & TS_USEDFPU)) { 107 clts(); 108 task_thread_info(current)->status |= TS_USEDFPU; 109 } 110 err = restore_fpu_checking((__force struct i387_fxsave_struct *)buf); 111 if (unlikely(err)) { 112 /* 113 * Encountered an error while doing the restore from the 114 * user buffer, clear the fpu state. 115 */ 116 clear_fpu(tsk); 117 clear_used_math(); 118 } 119 return err; 120 } 121 122 /* 123 * Do a signal return; undo the signal stack. 124 */ 125 static int 126 restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc, 127 unsigned long *pax) 128 { 129 unsigned int err = 0; 130 131 /* Always make any pending restarted system calls return -EINTR */ 132 current_thread_info()->restart_block.fn = do_no_restart_syscall; 133 134 #define COPY(x) err |= __get_user(regs->x, &sc->x) 135 136 COPY(di); COPY(si); COPY(bp); COPY(sp); COPY(bx); 137 COPY(dx); COPY(cx); COPY(ip); 138 COPY(r8); 139 COPY(r9); 140 COPY(r10); 141 COPY(r11); 142 COPY(r12); 143 COPY(r13); 144 COPY(r14); 145 COPY(r15); 146 147 /* Kernel saves and restores only the CS segment register on signals, 148 * which is the bare minimum needed to allow mixed 32/64-bit code. 149 * App's signal handler can save/restore other segments if needed. */ 150 { 151 unsigned cs; 152 err |= __get_user(cs, &sc->cs); 153 regs->cs = cs | 3; /* Force into user mode */ 154 } 155 156 { 157 unsigned int tmpflags; 158 err |= __get_user(tmpflags, &sc->flags); 159 regs->flags = (regs->flags & ~FIX_EFLAGS) | (tmpflags & FIX_EFLAGS); 160 regs->orig_ax = -1; /* disable syscall checks */ 161 } 162 163 { 164 struct _fpstate __user * buf; 165 err |= __get_user(buf, &sc->fpstate); 166 167 if (buf) { 168 if (!access_ok(VERIFY_READ, buf, sizeof(*buf))) 169 goto badframe; 170 err |= restore_i387(buf); 171 } else { 172 struct task_struct *me = current; 173 if (used_math()) { 174 clear_fpu(me); 175 clear_used_math(); 176 } 177 } 178 } 179 180 err |= __get_user(*pax, &sc->ax); 181 return err; 182 183 badframe: 184 return 1; 185 } 186 187 asmlinkage long sys_rt_sigreturn(struct pt_regs *regs) 188 { 189 struct rt_sigframe __user *frame; 190 sigset_t set; 191 unsigned long ax; 192 193 frame = (struct rt_sigframe __user *)(regs->sp - sizeof(long)); 194 if (!access_ok(VERIFY_READ, frame, sizeof(*frame))) 195 goto badframe; 196 if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set))) 197 goto badframe; 198 199 sigdelsetmask(&set, ~_BLOCKABLE); 200 spin_lock_irq(¤t->sighand->siglock); 201 current->blocked = set; 202 recalc_sigpending(); 203 spin_unlock_irq(¤t->sighand->siglock); 204 205 if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &ax)) 206 goto badframe; 207 208 if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->sp) == -EFAULT) 209 goto badframe; 210 211 return ax; 212 213 badframe: 214 signal_fault(regs,frame,"sigreturn"); 215 return 0; 216 } 217 218 /* 219 * Set up a signal frame. 220 */ 221 222 static inline int 223 setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs, unsigned long mask, struct task_struct *me) 224 { 225 int err = 0; 226 227 err |= __put_user(regs->cs, &sc->cs); 228 err |= __put_user(0, &sc->gs); 229 err |= __put_user(0, &sc->fs); 230 231 err |= __put_user(regs->di, &sc->di); 232 err |= __put_user(regs->si, &sc->si); 233 err |= __put_user(regs->bp, &sc->bp); 234 err |= __put_user(regs->sp, &sc->sp); 235 err |= __put_user(regs->bx, &sc->bx); 236 err |= __put_user(regs->dx, &sc->dx); 237 err |= __put_user(regs->cx, &sc->cx); 238 err |= __put_user(regs->ax, &sc->ax); 239 err |= __put_user(regs->r8, &sc->r8); 240 err |= __put_user(regs->r9, &sc->r9); 241 err |= __put_user(regs->r10, &sc->r10); 242 err |= __put_user(regs->r11, &sc->r11); 243 err |= __put_user(regs->r12, &sc->r12); 244 err |= __put_user(regs->r13, &sc->r13); 245 err |= __put_user(regs->r14, &sc->r14); 246 err |= __put_user(regs->r15, &sc->r15); 247 err |= __put_user(me->thread.trap_no, &sc->trapno); 248 err |= __put_user(me->thread.error_code, &sc->err); 249 err |= __put_user(regs->ip, &sc->ip); 250 err |= __put_user(regs->flags, &sc->flags); 251 err |= __put_user(mask, &sc->oldmask); 252 err |= __put_user(me->thread.cr2, &sc->cr2); 253 254 return err; 255 } 256 257 /* 258 * Determine which stack to use.. 259 */ 260 261 static void __user * 262 get_stack(struct k_sigaction *ka, struct pt_regs *regs, unsigned long size) 263 { 264 unsigned long sp; 265 266 /* Default to using normal stack - redzone*/ 267 sp = regs->sp - 128; 268 269 /* This is the X/Open sanctioned signal stack switching. */ 270 if (ka->sa.sa_flags & SA_ONSTACK) { 271 if (sas_ss_flags(sp) == 0) 272 sp = current->sas_ss_sp + current->sas_ss_size; 273 } 274 275 return (void __user *)round_down(sp - size, 16); 276 } 277 278 static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info, 279 sigset_t *set, struct pt_regs * regs) 280 { 281 struct rt_sigframe __user *frame; 282 struct _fpstate __user *fp = NULL; 283 int err = 0; 284 struct task_struct *me = current; 285 286 if (used_math()) { 287 fp = get_stack(ka, regs, sizeof(struct _fpstate)); 288 frame = (void __user *)round_down( 289 (unsigned long)fp - sizeof(struct rt_sigframe), 16) - 8; 290 291 if (!access_ok(VERIFY_WRITE, fp, sizeof(struct _fpstate))) 292 goto give_sigsegv; 293 294 if (save_i387(fp) < 0) 295 err |= -1; 296 } else 297 frame = get_stack(ka, regs, sizeof(struct rt_sigframe)) - 8; 298 299 if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame))) 300 goto give_sigsegv; 301 302 if (ka->sa.sa_flags & SA_SIGINFO) { 303 err |= copy_siginfo_to_user(&frame->info, info); 304 if (err) 305 goto give_sigsegv; 306 } 307 308 /* Create the ucontext. */ 309 err |= __put_user(0, &frame->uc.uc_flags); 310 err |= __put_user(0, &frame->uc.uc_link); 311 err |= __put_user(me->sas_ss_sp, &frame->uc.uc_stack.ss_sp); 312 err |= __put_user(sas_ss_flags(regs->sp), 313 &frame->uc.uc_stack.ss_flags); 314 err |= __put_user(me->sas_ss_size, &frame->uc.uc_stack.ss_size); 315 err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, set->sig[0], me); 316 err |= __put_user(fp, &frame->uc.uc_mcontext.fpstate); 317 if (sizeof(*set) == 16) { 318 __put_user(set->sig[0], &frame->uc.uc_sigmask.sig[0]); 319 __put_user(set->sig[1], &frame->uc.uc_sigmask.sig[1]); 320 } else 321 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)); 322 323 /* Set up to return from userspace. If provided, use a stub 324 already in userspace. */ 325 /* x86-64 should always use SA_RESTORER. */ 326 if (ka->sa.sa_flags & SA_RESTORER) { 327 err |= __put_user(ka->sa.sa_restorer, &frame->pretcode); 328 } else { 329 /* could use a vstub here */ 330 goto give_sigsegv; 331 } 332 333 if (err) 334 goto give_sigsegv; 335 336 /* Set up registers for signal handler */ 337 regs->di = sig; 338 /* In case the signal handler was declared without prototypes */ 339 regs->ax = 0; 340 341 /* This also works for non SA_SIGINFO handlers because they expect the 342 next argument after the signal number on the stack. */ 343 regs->si = (unsigned long)&frame->info; 344 regs->dx = (unsigned long)&frame->uc; 345 regs->ip = (unsigned long) ka->sa.sa_handler; 346 347 regs->sp = (unsigned long)frame; 348 349 /* Set up the CS register to run signal handlers in 64-bit mode, 350 even if the handler happens to be interrupting 32-bit code. */ 351 regs->cs = __USER_CS; 352 353 return 0; 354 355 give_sigsegv: 356 force_sigsegv(sig, current); 357 return -EFAULT; 358 } 359 360 /* 361 * OK, we're invoking a handler 362 */ 363 364 static int 365 handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka, 366 sigset_t *oldset, struct pt_regs *regs) 367 { 368 int ret; 369 370 /* Are we from a system call? */ 371 if (syscall_get_nr(current, regs) >= 0) { 372 /* If so, check system call restarting.. */ 373 switch (syscall_get_error(current, regs)) { 374 case -ERESTART_RESTARTBLOCK: 375 case -ERESTARTNOHAND: 376 regs->ax = -EINTR; 377 break; 378 379 case -ERESTARTSYS: 380 if (!(ka->sa.sa_flags & SA_RESTART)) { 381 regs->ax = -EINTR; 382 break; 383 } 384 /* fallthrough */ 385 case -ERESTARTNOINTR: 386 regs->ax = regs->orig_ax; 387 regs->ip -= 2; 388 break; 389 } 390 } 391 392 /* 393 * If TF is set due to a debugger (TIF_FORCED_TF), clear the TF 394 * flag so that register information in the sigcontext is correct. 395 */ 396 if (unlikely(regs->flags & X86_EFLAGS_TF) && 397 likely(test_and_clear_thread_flag(TIF_FORCED_TF))) 398 regs->flags &= ~X86_EFLAGS_TF; 399 400 #ifdef CONFIG_IA32_EMULATION 401 if (test_thread_flag(TIF_IA32)) { 402 if (ka->sa.sa_flags & SA_SIGINFO) 403 ret = ia32_setup_rt_frame(sig, ka, info, oldset, regs); 404 else 405 ret = ia32_setup_frame(sig, ka, oldset, regs); 406 } else 407 #endif 408 ret = setup_rt_frame(sig, ka, info, oldset, regs); 409 410 if (ret == 0) { 411 /* 412 * This has nothing to do with segment registers, 413 * despite the name. This magic affects uaccess.h 414 * macros' behavior. Reset it to the normal setting. 415 */ 416 set_fs(USER_DS); 417 418 /* 419 * Clear the direction flag as per the ABI for function entry. 420 */ 421 regs->flags &= ~X86_EFLAGS_DF; 422 423 /* 424 * Clear TF when entering the signal handler, but 425 * notify any tracer that was single-stepping it. 426 * The tracer may want to single-step inside the 427 * handler too. 428 */ 429 regs->flags &= ~X86_EFLAGS_TF; 430 431 spin_lock_irq(¤t->sighand->siglock); 432 sigorsets(¤t->blocked,¤t->blocked,&ka->sa.sa_mask); 433 if (!(ka->sa.sa_flags & SA_NODEFER)) 434 sigaddset(¤t->blocked,sig); 435 recalc_sigpending(); 436 spin_unlock_irq(¤t->sighand->siglock); 437 438 tracehook_signal_handler(sig, info, ka, regs, 439 test_thread_flag(TIF_SINGLESTEP)); 440 } 441 442 return ret; 443 } 444 445 /* 446 * Note that 'init' is a special process: it doesn't get signals it doesn't 447 * want to handle. Thus you cannot kill init even with a SIGKILL even by 448 * mistake. 449 */ 450 static void do_signal(struct pt_regs *regs) 451 { 452 struct k_sigaction ka; 453 siginfo_t info; 454 int signr; 455 sigset_t *oldset; 456 457 /* 458 * We want the common case to go fast, which is why we may in certain 459 * cases get here from kernel mode. Just return without doing anything 460 * if so. 461 * X86_32: vm86 regs switched out by assembly code before reaching 462 * here, so testing against kernel CS suffices. 463 */ 464 if (!user_mode(regs)) 465 return; 466 467 if (current_thread_info()->status & TS_RESTORE_SIGMASK) 468 oldset = ¤t->saved_sigmask; 469 else 470 oldset = ¤t->blocked; 471 472 signr = get_signal_to_deliver(&info, &ka, regs, NULL); 473 if (signr > 0) { 474 /* Re-enable any watchpoints before delivering the 475 * signal to user space. The processor register will 476 * have been cleared if the watchpoint triggered 477 * inside the kernel. 478 */ 479 if (current->thread.debugreg7) 480 set_debugreg(current->thread.debugreg7, 7); 481 482 /* Whee! Actually deliver the signal. */ 483 if (handle_signal(signr, &info, &ka, oldset, regs) == 0) { 484 /* 485 * A signal was successfully delivered; the saved 486 * sigmask will have been stored in the signal frame, 487 * and will be restored by sigreturn, so we can simply 488 * clear the TS_RESTORE_SIGMASK flag. 489 */ 490 current_thread_info()->status &= ~TS_RESTORE_SIGMASK; 491 } 492 return; 493 } 494 495 /* Did we come from a system call? */ 496 if (syscall_get_nr(current, regs) >= 0) { 497 /* Restart the system call - no handlers present */ 498 switch (syscall_get_error(current, regs)) { 499 case -ERESTARTNOHAND: 500 case -ERESTARTSYS: 501 case -ERESTARTNOINTR: 502 regs->ax = regs->orig_ax; 503 regs->ip -= 2; 504 break; 505 case -ERESTART_RESTARTBLOCK: 506 regs->ax = test_thread_flag(TIF_IA32) ? 507 __NR_ia32_restart_syscall : 508 __NR_restart_syscall; 509 regs->ip -= 2; 510 break; 511 } 512 } 513 514 /* 515 * If there's no signal to deliver, we just put the saved sigmask 516 * back. 517 */ 518 if (current_thread_info()->status & TS_RESTORE_SIGMASK) { 519 current_thread_info()->status &= ~TS_RESTORE_SIGMASK; 520 sigprocmask(SIG_SETMASK, ¤t->saved_sigmask, NULL); 521 } 522 } 523 524 void do_notify_resume(struct pt_regs *regs, void *unused, 525 __u32 thread_info_flags) 526 { 527 #ifdef CONFIG_X86_MCE 528 /* notify userspace of pending MCEs */ 529 if (thread_info_flags & _TIF_MCE_NOTIFY) 530 mce_notify_user(); 531 #endif /* CONFIG_X86_MCE */ 532 533 /* deal with pending signal delivery */ 534 if (thread_info_flags & _TIF_SIGPENDING) 535 do_signal(regs); 536 537 if (thread_info_flags & _TIF_NOTIFY_RESUME) { 538 clear_thread_flag(TIF_NOTIFY_RESUME); 539 tracehook_notify_resume(regs); 540 } 541 } 542 543 void signal_fault(struct pt_regs *regs, void __user *frame, char *where) 544 { 545 struct task_struct *me = current; 546 if (show_unhandled_signals && printk_ratelimit()) { 547 printk("%s[%d] bad frame in %s frame:%p ip:%lx sp:%lx orax:%lx", 548 me->comm,me->pid,where,frame,regs->ip,regs->sp,regs->orig_ax); 549 print_vma_addr(" in ", regs->ip); 550 printk("\n"); 551 } 552 553 force_sig(SIGSEGV, me); 554 } 555