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 <linux/uaccess.h> 24 25 #include <asm/processor.h> 26 #include <asm/ucontext.h> 27 #include <asm/i387.h> 28 #include <asm/proto.h> 29 #include <asm/ia32_unistd.h> 30 #include <asm/mce.h> 31 #include <asm/syscall.h> 32 #include <asm/syscalls.h> 33 #include "sigframe.h" 34 35 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP))) 36 37 #define __FIX_EFLAGS (X86_EFLAGS_AC | X86_EFLAGS_OF | \ 38 X86_EFLAGS_DF | X86_EFLAGS_TF | X86_EFLAGS_SF | \ 39 X86_EFLAGS_ZF | X86_EFLAGS_AF | X86_EFLAGS_PF | \ 40 X86_EFLAGS_CF) 41 42 #ifdef CONFIG_X86_32 43 # define FIX_EFLAGS (__FIX_EFLAGS | X86_EFLAGS_RF) 44 #else 45 # define FIX_EFLAGS __FIX_EFLAGS 46 #endif 47 48 asmlinkage long 49 sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss, 50 struct pt_regs *regs) 51 { 52 return do_sigaltstack(uss, uoss, regs->sp); 53 } 54 55 #define COPY(x) { \ 56 err |= __get_user(regs->x, &sc->x); \ 57 } 58 59 #define COPY_SEG_STRICT(seg) { \ 60 unsigned short tmp; \ 61 err |= __get_user(tmp, &sc->seg); \ 62 regs->seg = tmp | 3; \ 63 } 64 65 /* 66 * Do a signal return; undo the signal stack. 67 */ 68 static int 69 restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc, 70 unsigned long *pax) 71 { 72 unsigned int err = 0; 73 74 /* Always make any pending restarted system calls return -EINTR */ 75 current_thread_info()->restart_block.fn = do_no_restart_syscall; 76 77 COPY(di); COPY(si); COPY(bp); COPY(sp); COPY(bx); 78 COPY(dx); COPY(cx); COPY(ip); 79 COPY(r8); 80 COPY(r9); 81 COPY(r10); 82 COPY(r11); 83 COPY(r12); 84 COPY(r13); 85 COPY(r14); 86 COPY(r15); 87 88 /* Kernel saves and restores only the CS segment register on signals, 89 * which is the bare minimum needed to allow mixed 32/64-bit code. 90 * App's signal handler can save/restore other segments if needed. */ 91 COPY_SEG_STRICT(cs); 92 93 { 94 unsigned int tmpflags; 95 err |= __get_user(tmpflags, &sc->flags); 96 regs->flags = (regs->flags & ~FIX_EFLAGS) | (tmpflags & FIX_EFLAGS); 97 regs->orig_ax = -1; /* disable syscall checks */ 98 } 99 100 { 101 void __user *buf; 102 103 err |= __get_user(buf, &sc->fpstate); 104 err |= restore_i387_xstate(buf); 105 } 106 107 err |= __get_user(*pax, &sc->ax); 108 return err; 109 } 110 111 static long do_rt_sigreturn(struct pt_regs *regs) 112 { 113 struct rt_sigframe __user *frame; 114 unsigned long ax; 115 sigset_t set; 116 117 frame = (struct rt_sigframe __user *)(regs->sp - sizeof(long)); 118 if (!access_ok(VERIFY_READ, frame, sizeof(*frame))) 119 goto badframe; 120 if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set))) 121 goto badframe; 122 123 sigdelsetmask(&set, ~_BLOCKABLE); 124 spin_lock_irq(¤t->sighand->siglock); 125 current->blocked = set; 126 recalc_sigpending(); 127 spin_unlock_irq(¤t->sighand->siglock); 128 129 if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &ax)) 130 goto badframe; 131 132 if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->sp) == -EFAULT) 133 goto badframe; 134 135 return ax; 136 137 badframe: 138 signal_fault(regs, frame, "rt_sigreturn"); 139 return 0; 140 } 141 142 asmlinkage long sys_rt_sigreturn(struct pt_regs *regs) 143 { 144 return do_rt_sigreturn(regs); 145 } 146 147 /* 148 * Set up a signal frame. 149 */ 150 151 static inline int 152 setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs, 153 unsigned long mask, struct task_struct *me) 154 { 155 int err = 0; 156 157 err |= __put_user(regs->cs, &sc->cs); 158 err |= __put_user(0, &sc->gs); 159 err |= __put_user(0, &sc->fs); 160 161 err |= __put_user(regs->di, &sc->di); 162 err |= __put_user(regs->si, &sc->si); 163 err |= __put_user(regs->bp, &sc->bp); 164 err |= __put_user(regs->sp, &sc->sp); 165 err |= __put_user(regs->bx, &sc->bx); 166 err |= __put_user(regs->dx, &sc->dx); 167 err |= __put_user(regs->cx, &sc->cx); 168 err |= __put_user(regs->ax, &sc->ax); 169 err |= __put_user(regs->r8, &sc->r8); 170 err |= __put_user(regs->r9, &sc->r9); 171 err |= __put_user(regs->r10, &sc->r10); 172 err |= __put_user(regs->r11, &sc->r11); 173 err |= __put_user(regs->r12, &sc->r12); 174 err |= __put_user(regs->r13, &sc->r13); 175 err |= __put_user(regs->r14, &sc->r14); 176 err |= __put_user(regs->r15, &sc->r15); 177 err |= __put_user(me->thread.trap_no, &sc->trapno); 178 err |= __put_user(me->thread.error_code, &sc->err); 179 err |= __put_user(regs->ip, &sc->ip); 180 err |= __put_user(regs->flags, &sc->flags); 181 err |= __put_user(mask, &sc->oldmask); 182 err |= __put_user(me->thread.cr2, &sc->cr2); 183 184 return err; 185 } 186 187 /* 188 * Determine which stack to use.. 189 */ 190 191 static void __user * 192 get_stack(struct k_sigaction *ka, struct pt_regs *regs, unsigned long size) 193 { 194 unsigned long sp; 195 196 /* Default to using normal stack - redzone*/ 197 sp = regs->sp - 128; 198 199 /* This is the X/Open sanctioned signal stack switching. */ 200 if (ka->sa.sa_flags & SA_ONSTACK) { 201 if (sas_ss_flags(sp) == 0) 202 sp = current->sas_ss_sp + current->sas_ss_size; 203 } 204 205 return (void __user *)round_down(sp - size, 64); 206 } 207 208 static int __setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info, 209 sigset_t *set, struct pt_regs *regs) 210 { 211 struct rt_sigframe __user *frame; 212 void __user *fp = NULL; 213 int err = 0; 214 struct task_struct *me = current; 215 216 if (used_math()) { 217 fp = get_stack(ka, regs, sig_xstate_size); 218 frame = (void __user *)round_down( 219 (unsigned long)fp - sizeof(struct rt_sigframe), 16) - 8; 220 221 if (save_i387_xstate(fp) < 0) 222 return -EFAULT; 223 } else 224 frame = get_stack(ka, regs, sizeof(struct rt_sigframe)) - 8; 225 226 if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame))) 227 return -EFAULT; 228 229 if (ka->sa.sa_flags & SA_SIGINFO) { 230 if (copy_siginfo_to_user(&frame->info, info)) 231 return -EFAULT; 232 } 233 234 /* Create the ucontext. */ 235 if (cpu_has_xsave) 236 err |= __put_user(UC_FP_XSTATE, &frame->uc.uc_flags); 237 else 238 err |= __put_user(0, &frame->uc.uc_flags); 239 err |= __put_user(0, &frame->uc.uc_link); 240 err |= __put_user(me->sas_ss_sp, &frame->uc.uc_stack.ss_sp); 241 err |= __put_user(sas_ss_flags(regs->sp), 242 &frame->uc.uc_stack.ss_flags); 243 err |= __put_user(me->sas_ss_size, &frame->uc.uc_stack.ss_size); 244 err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, set->sig[0], me); 245 err |= __put_user(fp, &frame->uc.uc_mcontext.fpstate); 246 if (sizeof(*set) == 16) { 247 __put_user(set->sig[0], &frame->uc.uc_sigmask.sig[0]); 248 __put_user(set->sig[1], &frame->uc.uc_sigmask.sig[1]); 249 } else 250 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)); 251 252 /* Set up to return from userspace. If provided, use a stub 253 already in userspace. */ 254 /* x86-64 should always use SA_RESTORER. */ 255 if (ka->sa.sa_flags & SA_RESTORER) { 256 err |= __put_user(ka->sa.sa_restorer, &frame->pretcode); 257 } else { 258 /* could use a vstub here */ 259 return -EFAULT; 260 } 261 262 if (err) 263 return -EFAULT; 264 265 /* Set up registers for signal handler */ 266 regs->di = sig; 267 /* In case the signal handler was declared without prototypes */ 268 regs->ax = 0; 269 270 /* This also works for non SA_SIGINFO handlers because they expect the 271 next argument after the signal number on the stack. */ 272 regs->si = (unsigned long)&frame->info; 273 regs->dx = (unsigned long)&frame->uc; 274 regs->ip = (unsigned long) ka->sa.sa_handler; 275 276 regs->sp = (unsigned long)frame; 277 278 /* Set up the CS register to run signal handlers in 64-bit mode, 279 even if the handler happens to be interrupting 32-bit code. */ 280 regs->cs = __USER_CS; 281 282 return 0; 283 } 284 285 /* 286 * OK, we're invoking a handler 287 */ 288 static int signr_convert(int sig) 289 { 290 return sig; 291 } 292 293 #ifdef CONFIG_IA32_EMULATION 294 #define is_ia32 test_thread_flag(TIF_IA32) 295 #else 296 #define is_ia32 0 297 #endif 298 299 static int 300 setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info, 301 sigset_t *set, struct pt_regs *regs) 302 { 303 int usig = signr_convert(sig); 304 int ret; 305 306 /* Set up the stack frame */ 307 if (is_ia32) { 308 if (ka->sa.sa_flags & SA_SIGINFO) 309 ret = ia32_setup_rt_frame(usig, ka, info, set, regs); 310 else 311 ret = ia32_setup_frame(usig, ka, set, regs); 312 } else 313 ret = __setup_rt_frame(sig, ka, info, set, regs); 314 315 if (ret) { 316 force_sigsegv(sig, current); 317 return -EFAULT; 318 } 319 320 return ret; 321 } 322 323 static int 324 handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka, 325 sigset_t *oldset, struct pt_regs *regs) 326 { 327 int ret; 328 329 /* Are we from a system call? */ 330 if (syscall_get_nr(current, regs) >= 0) { 331 /* If so, check system call restarting.. */ 332 switch (syscall_get_error(current, regs)) { 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 ret = setup_rt_frame(sig, ka, info, oldset, regs); 360 361 if (ret) 362 return ret; 363 364 #ifdef CONFIG_X86_64 365 /* 366 * This has nothing to do with segment registers, 367 * despite the name. This magic affects uaccess.h 368 * macros' behavior. Reset it to the normal setting. 369 */ 370 set_fs(USER_DS); 371 #endif 372 373 /* 374 * Clear the direction flag as per the ABI for function entry. 375 */ 376 regs->flags &= ~X86_EFLAGS_DF; 377 378 /* 379 * Clear TF when entering the signal handler, but 380 * notify any tracer that was single-stepping it. 381 * The tracer may want to single-step inside the 382 * handler too. 383 */ 384 regs->flags &= ~X86_EFLAGS_TF; 385 386 spin_lock_irq(¤t->sighand->siglock); 387 sigorsets(¤t->blocked, ¤t->blocked, &ka->sa.sa_mask); 388 if (!(ka->sa.sa_flags & SA_NODEFER)) 389 sigaddset(¤t->blocked, sig); 390 recalc_sigpending(); 391 spin_unlock_irq(¤t->sighand->siglock); 392 393 tracehook_signal_handler(sig, info, ka, regs, 394 test_thread_flag(TIF_SINGLESTEP)); 395 396 return 0; 397 } 398 399 #define NR_restart_syscall \ 400 test_thread_flag(TIF_IA32) ? __NR_ia32_restart_syscall : __NR_restart_syscall 401 /* 402 * Note that 'init' is a special process: it doesn't get signals it doesn't 403 * want to handle. Thus you cannot kill init even with a SIGKILL even by 404 * mistake. 405 */ 406 static void do_signal(struct pt_regs *regs) 407 { 408 struct k_sigaction ka; 409 siginfo_t info; 410 int signr; 411 sigset_t *oldset; 412 413 /* 414 * We want the common case to go fast, which is why we may in certain 415 * cases get here from kernel mode. Just return without doing anything 416 * if so. 417 * X86_32: vm86 regs switched out by assembly code before reaching 418 * here, so testing against kernel CS suffices. 419 */ 420 if (!user_mode(regs)) 421 return; 422 423 if (current_thread_info()->status & TS_RESTORE_SIGMASK) 424 oldset = ¤t->saved_sigmask; 425 else 426 oldset = ¤t->blocked; 427 428 signr = get_signal_to_deliver(&info, &ka, regs, NULL); 429 if (signr > 0) { 430 /* 431 * Re-enable any watchpoints before delivering the 432 * signal to user space. The processor register will 433 * have been cleared if the watchpoint triggered 434 * inside the kernel. 435 */ 436 if (current->thread.debugreg7) 437 set_debugreg(current->thread.debugreg7, 7); 438 439 /* Whee! Actually deliver the signal. */ 440 if (handle_signal(signr, &info, &ka, oldset, regs) == 0) { 441 /* 442 * A signal was successfully delivered; the saved 443 * sigmask will have been stored in the signal frame, 444 * and will be restored by sigreturn, so we can simply 445 * clear the TS_RESTORE_SIGMASK flag. 446 */ 447 current_thread_info()->status &= ~TS_RESTORE_SIGMASK; 448 } 449 return; 450 } 451 452 /* Did we come from a system call? */ 453 if (syscall_get_nr(current, regs) >= 0) { 454 /* Restart the system call - no handlers present */ 455 switch (syscall_get_error(current, regs)) { 456 case -ERESTARTNOHAND: 457 case -ERESTARTSYS: 458 case -ERESTARTNOINTR: 459 regs->ax = regs->orig_ax; 460 regs->ip -= 2; 461 break; 462 463 case -ERESTART_RESTARTBLOCK: 464 regs->ax = NR_restart_syscall; 465 regs->ip -= 2; 466 break; 467 } 468 } 469 470 /* 471 * If there's no signal to deliver, we just put the saved sigmask 472 * back. 473 */ 474 if (current_thread_info()->status & TS_RESTORE_SIGMASK) { 475 current_thread_info()->status &= ~TS_RESTORE_SIGMASK; 476 sigprocmask(SIG_SETMASK, ¤t->saved_sigmask, NULL); 477 } 478 } 479 480 /* 481 * notification of userspace execution resumption 482 * - triggered by the TIF_WORK_MASK flags 483 */ 484 void 485 do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags) 486 { 487 #if defined(CONFIG_X86_64) && defined(CONFIG_X86_MCE) 488 /* notify userspace of pending MCEs */ 489 if (thread_info_flags & _TIF_MCE_NOTIFY) 490 mce_notify_user(); 491 #endif /* CONFIG_X86_64 && CONFIG_X86_MCE */ 492 493 /* deal with pending signal delivery */ 494 if (thread_info_flags & _TIF_SIGPENDING) 495 do_signal(regs); 496 497 if (thread_info_flags & _TIF_NOTIFY_RESUME) { 498 clear_thread_flag(TIF_NOTIFY_RESUME); 499 tracehook_notify_resume(regs); 500 } 501 502 #ifdef CONFIG_X86_32 503 clear_thread_flag(TIF_IRET); 504 #endif /* CONFIG_X86_32 */ 505 } 506 507 void signal_fault(struct pt_regs *regs, void __user *frame, char *where) 508 { 509 struct task_struct *me = current; 510 511 if (show_unhandled_signals && printk_ratelimit()) { 512 printk(KERN_INFO 513 "%s[%d] bad frame in %s frame:%p ip:%lx sp:%lx orax:%lx", 514 me->comm, me->pid, where, frame, 515 regs->ip, regs->sp, regs->orig_ax); 516 print_vma_addr(" in ", regs->ip); 517 printk(KERN_CONT "\n"); 518 } 519 520 force_sig(SIGSEGV, me); 521 } 522