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 /* 56 * Do a signal return; undo the signal stack. 57 */ 58 static int 59 restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc, 60 unsigned long *pax) 61 { 62 unsigned int err = 0; 63 64 /* Always make any pending restarted system calls return -EINTR */ 65 current_thread_info()->restart_block.fn = do_no_restart_syscall; 66 67 #define COPY(x) (err |= __get_user(regs->x, &sc->x)) 68 69 COPY(di); COPY(si); COPY(bp); COPY(sp); COPY(bx); 70 COPY(dx); COPY(cx); COPY(ip); 71 COPY(r8); 72 COPY(r9); 73 COPY(r10); 74 COPY(r11); 75 COPY(r12); 76 COPY(r13); 77 COPY(r14); 78 COPY(r15); 79 80 /* Kernel saves and restores only the CS segment register on signals, 81 * which is the bare minimum needed to allow mixed 32/64-bit code. 82 * App's signal handler can save/restore other segments if needed. */ 83 { 84 unsigned cs; 85 err |= __get_user(cs, &sc->cs); 86 regs->cs = cs | 3; /* Force into user mode */ 87 } 88 89 { 90 unsigned int tmpflags; 91 err |= __get_user(tmpflags, &sc->flags); 92 regs->flags = (regs->flags & ~FIX_EFLAGS) | (tmpflags & FIX_EFLAGS); 93 regs->orig_ax = -1; /* disable syscall checks */ 94 } 95 96 { 97 void __user *buf; 98 99 err |= __get_user(buf, &sc->fpstate); 100 err |= restore_i387_xstate(buf); 101 } 102 103 err |= __get_user(*pax, &sc->ax); 104 return err; 105 } 106 107 static long do_rt_sigreturn(struct pt_regs *regs) 108 { 109 struct rt_sigframe __user *frame; 110 unsigned long ax; 111 sigset_t set; 112 113 frame = (struct rt_sigframe __user *)(regs->sp - sizeof(long)); 114 if (!access_ok(VERIFY_READ, frame, sizeof(*frame))) 115 goto badframe; 116 if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set))) 117 goto badframe; 118 119 sigdelsetmask(&set, ~_BLOCKABLE); 120 spin_lock_irq(¤t->sighand->siglock); 121 current->blocked = set; 122 recalc_sigpending(); 123 spin_unlock_irq(¤t->sighand->siglock); 124 125 if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &ax)) 126 goto badframe; 127 128 if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->sp) == -EFAULT) 129 goto badframe; 130 131 return ax; 132 133 badframe: 134 signal_fault(regs, frame, "rt_sigreturn"); 135 return 0; 136 } 137 138 asmlinkage long sys_rt_sigreturn(struct pt_regs *regs) 139 { 140 return do_rt_sigreturn(regs); 141 } 142 143 /* 144 * Set up a signal frame. 145 */ 146 147 static inline int 148 setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs, 149 unsigned long mask, struct task_struct *me) 150 { 151 int err = 0; 152 153 err |= __put_user(regs->cs, &sc->cs); 154 err |= __put_user(0, &sc->gs); 155 err |= __put_user(0, &sc->fs); 156 157 err |= __put_user(regs->di, &sc->di); 158 err |= __put_user(regs->si, &sc->si); 159 err |= __put_user(regs->bp, &sc->bp); 160 err |= __put_user(regs->sp, &sc->sp); 161 err |= __put_user(regs->bx, &sc->bx); 162 err |= __put_user(regs->dx, &sc->dx); 163 err |= __put_user(regs->cx, &sc->cx); 164 err |= __put_user(regs->ax, &sc->ax); 165 err |= __put_user(regs->r8, &sc->r8); 166 err |= __put_user(regs->r9, &sc->r9); 167 err |= __put_user(regs->r10, &sc->r10); 168 err |= __put_user(regs->r11, &sc->r11); 169 err |= __put_user(regs->r12, &sc->r12); 170 err |= __put_user(regs->r13, &sc->r13); 171 err |= __put_user(regs->r14, &sc->r14); 172 err |= __put_user(regs->r15, &sc->r15); 173 err |= __put_user(me->thread.trap_no, &sc->trapno); 174 err |= __put_user(me->thread.error_code, &sc->err); 175 err |= __put_user(regs->ip, &sc->ip); 176 err |= __put_user(regs->flags, &sc->flags); 177 err |= __put_user(mask, &sc->oldmask); 178 err |= __put_user(me->thread.cr2, &sc->cr2); 179 180 return err; 181 } 182 183 /* 184 * Determine which stack to use.. 185 */ 186 187 static void __user * 188 get_stack(struct k_sigaction *ka, struct pt_regs *regs, unsigned long size) 189 { 190 unsigned long sp; 191 192 /* Default to using normal stack - redzone*/ 193 sp = regs->sp - 128; 194 195 /* This is the X/Open sanctioned signal stack switching. */ 196 if (ka->sa.sa_flags & SA_ONSTACK) { 197 if (sas_ss_flags(sp) == 0) 198 sp = current->sas_ss_sp + current->sas_ss_size; 199 } 200 201 return (void __user *)round_down(sp - size, 64); 202 } 203 204 static int __setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info, 205 sigset_t *set, struct pt_regs *regs) 206 { 207 struct rt_sigframe __user *frame; 208 void __user *fp = NULL; 209 int err = 0; 210 struct task_struct *me = current; 211 212 if (used_math()) { 213 fp = get_stack(ka, regs, sig_xstate_size); 214 frame = (void __user *)round_down( 215 (unsigned long)fp - sizeof(struct rt_sigframe), 16) - 8; 216 217 if (save_i387_xstate(fp) < 0) 218 return -EFAULT; 219 } else 220 frame = get_stack(ka, regs, sizeof(struct rt_sigframe)) - 8; 221 222 if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame))) 223 return -EFAULT; 224 225 if (ka->sa.sa_flags & SA_SIGINFO) { 226 if (copy_siginfo_to_user(&frame->info, info)) 227 return -EFAULT; 228 } 229 230 /* Create the ucontext. */ 231 if (cpu_has_xsave) 232 err |= __put_user(UC_FP_XSTATE, &frame->uc.uc_flags); 233 else 234 err |= __put_user(0, &frame->uc.uc_flags); 235 err |= __put_user(0, &frame->uc.uc_link); 236 err |= __put_user(me->sas_ss_sp, &frame->uc.uc_stack.ss_sp); 237 err |= __put_user(sas_ss_flags(regs->sp), 238 &frame->uc.uc_stack.ss_flags); 239 err |= __put_user(me->sas_ss_size, &frame->uc.uc_stack.ss_size); 240 err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, set->sig[0], me); 241 err |= __put_user(fp, &frame->uc.uc_mcontext.fpstate); 242 if (sizeof(*set) == 16) { 243 __put_user(set->sig[0], &frame->uc.uc_sigmask.sig[0]); 244 __put_user(set->sig[1], &frame->uc.uc_sigmask.sig[1]); 245 } else 246 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)); 247 248 /* Set up to return from userspace. If provided, use a stub 249 already in userspace. */ 250 /* x86-64 should always use SA_RESTORER. */ 251 if (ka->sa.sa_flags & SA_RESTORER) { 252 err |= __put_user(ka->sa.sa_restorer, &frame->pretcode); 253 } else { 254 /* could use a vstub here */ 255 return -EFAULT; 256 } 257 258 if (err) 259 return -EFAULT; 260 261 /* Set up registers for signal handler */ 262 regs->di = sig; 263 /* In case the signal handler was declared without prototypes */ 264 regs->ax = 0; 265 266 /* This also works for non SA_SIGINFO handlers because they expect the 267 next argument after the signal number on the stack. */ 268 regs->si = (unsigned long)&frame->info; 269 regs->dx = (unsigned long)&frame->uc; 270 regs->ip = (unsigned long) ka->sa.sa_handler; 271 272 regs->sp = (unsigned long)frame; 273 274 /* Set up the CS register to run signal handlers in 64-bit mode, 275 even if the handler happens to be interrupting 32-bit code. */ 276 regs->cs = __USER_CS; 277 278 return 0; 279 } 280 281 /* 282 * OK, we're invoking a handler 283 */ 284 static int 285 setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info, 286 sigset_t *set, struct pt_regs *regs) 287 { 288 int ret; 289 290 #ifdef CONFIG_IA32_EMULATION 291 if (test_thread_flag(TIF_IA32)) { 292 if (ka->sa.sa_flags & SA_SIGINFO) 293 ret = ia32_setup_rt_frame(sig, ka, info, set, regs); 294 else 295 ret = ia32_setup_frame(sig, ka, set, regs); 296 } else 297 #endif 298 ret = __setup_rt_frame(sig, ka, info, set, regs); 299 300 if (ret) { 301 force_sigsegv(sig, current); 302 return -EFAULT; 303 } 304 305 return ret; 306 } 307 308 static int 309 handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka, 310 sigset_t *oldset, struct pt_regs *regs) 311 { 312 int ret; 313 314 /* Are we from a system call? */ 315 if (syscall_get_nr(current, regs) >= 0) { 316 /* If so, check system call restarting.. */ 317 switch (syscall_get_error(current, regs)) { 318 case -ERESTART_RESTARTBLOCK: 319 case -ERESTARTNOHAND: 320 regs->ax = -EINTR; 321 break; 322 323 case -ERESTARTSYS: 324 if (!(ka->sa.sa_flags & SA_RESTART)) { 325 regs->ax = -EINTR; 326 break; 327 } 328 /* fallthrough */ 329 case -ERESTARTNOINTR: 330 regs->ax = regs->orig_ax; 331 regs->ip -= 2; 332 break; 333 } 334 } 335 336 /* 337 * If TF is set due to a debugger (TIF_FORCED_TF), clear the TF 338 * flag so that register information in the sigcontext is correct. 339 */ 340 if (unlikely(regs->flags & X86_EFLAGS_TF) && 341 likely(test_and_clear_thread_flag(TIF_FORCED_TF))) 342 regs->flags &= ~X86_EFLAGS_TF; 343 344 ret = setup_rt_frame(sig, ka, info, oldset, regs); 345 346 if (ret) 347 return ret; 348 349 #ifdef CONFIG_X86_64 350 /* 351 * This has nothing to do with segment registers, 352 * despite the name. This magic affects uaccess.h 353 * macros' behavior. Reset it to the normal setting. 354 */ 355 set_fs(USER_DS); 356 #endif 357 358 /* 359 * Clear the direction flag as per the ABI for function entry. 360 */ 361 regs->flags &= ~X86_EFLAGS_DF; 362 363 /* 364 * Clear TF when entering the signal handler, but 365 * notify any tracer that was single-stepping it. 366 * The tracer may want to single-step inside the 367 * handler too. 368 */ 369 regs->flags &= ~X86_EFLAGS_TF; 370 371 spin_lock_irq(¤t->sighand->siglock); 372 sigorsets(¤t->blocked, ¤t->blocked, &ka->sa.sa_mask); 373 if (!(ka->sa.sa_flags & SA_NODEFER)) 374 sigaddset(¤t->blocked, sig); 375 recalc_sigpending(); 376 spin_unlock_irq(¤t->sighand->siglock); 377 378 tracehook_signal_handler(sig, info, ka, regs, 379 test_thread_flag(TIF_SINGLESTEP)); 380 381 return 0; 382 } 383 384 #define NR_restart_syscall \ 385 test_thread_flag(TIF_IA32) ? __NR_ia32_restart_syscall : __NR_restart_syscall 386 /* 387 * Note that 'init' is a special process: it doesn't get signals it doesn't 388 * want to handle. Thus you cannot kill init even with a SIGKILL even by 389 * mistake. 390 */ 391 static void do_signal(struct pt_regs *regs) 392 { 393 struct k_sigaction ka; 394 siginfo_t info; 395 int signr; 396 sigset_t *oldset; 397 398 /* 399 * We want the common case to go fast, which is why we may in certain 400 * cases get here from kernel mode. Just return without doing anything 401 * if so. 402 * X86_32: vm86 regs switched out by assembly code before reaching 403 * here, so testing against kernel CS suffices. 404 */ 405 if (!user_mode(regs)) 406 return; 407 408 if (current_thread_info()->status & TS_RESTORE_SIGMASK) 409 oldset = ¤t->saved_sigmask; 410 else 411 oldset = ¤t->blocked; 412 413 signr = get_signal_to_deliver(&info, &ka, regs, NULL); 414 if (signr > 0) { 415 /* 416 * Re-enable any watchpoints before delivering the 417 * signal to user space. The processor register will 418 * have been cleared if the watchpoint triggered 419 * inside the kernel. 420 */ 421 if (current->thread.debugreg7) 422 set_debugreg(current->thread.debugreg7, 7); 423 424 /* Whee! Actually deliver the signal. */ 425 if (handle_signal(signr, &info, &ka, oldset, regs) == 0) { 426 /* 427 * A signal was successfully delivered; the saved 428 * sigmask will have been stored in the signal frame, 429 * and will be restored by sigreturn, so we can simply 430 * clear the TS_RESTORE_SIGMASK flag. 431 */ 432 current_thread_info()->status &= ~TS_RESTORE_SIGMASK; 433 } 434 return; 435 } 436 437 /* Did we come from a system call? */ 438 if (syscall_get_nr(current, regs) >= 0) { 439 /* Restart the system call - no handlers present */ 440 switch (syscall_get_error(current, regs)) { 441 case -ERESTARTNOHAND: 442 case -ERESTARTSYS: 443 case -ERESTARTNOINTR: 444 regs->ax = regs->orig_ax; 445 regs->ip -= 2; 446 break; 447 448 case -ERESTART_RESTARTBLOCK: 449 regs->ax = NR_restart_syscall; 450 regs->ip -= 2; 451 break; 452 } 453 } 454 455 /* 456 * If there's no signal to deliver, we just put the saved sigmask 457 * back. 458 */ 459 if (current_thread_info()->status & TS_RESTORE_SIGMASK) { 460 current_thread_info()->status &= ~TS_RESTORE_SIGMASK; 461 sigprocmask(SIG_SETMASK, ¤t->saved_sigmask, NULL); 462 } 463 } 464 465 /* 466 * notification of userspace execution resumption 467 * - triggered by the TIF_WORK_MASK flags 468 */ 469 void 470 do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags) 471 { 472 #if defined(CONFIG_X86_64) && defined(CONFIG_X86_MCE) 473 /* notify userspace of pending MCEs */ 474 if (thread_info_flags & _TIF_MCE_NOTIFY) 475 mce_notify_user(); 476 #endif /* CONFIG_X86_64 && CONFIG_X86_MCE */ 477 478 /* deal with pending signal delivery */ 479 if (thread_info_flags & _TIF_SIGPENDING) 480 do_signal(regs); 481 482 if (thread_info_flags & _TIF_NOTIFY_RESUME) { 483 clear_thread_flag(TIF_NOTIFY_RESUME); 484 tracehook_notify_resume(regs); 485 } 486 487 #ifdef CONFIG_X86_32 488 clear_thread_flag(TIF_IRET); 489 #endif /* CONFIG_X86_32 */ 490 } 491 492 void signal_fault(struct pt_regs *regs, void __user *frame, char *where) 493 { 494 struct task_struct *me = current; 495 496 if (show_unhandled_signals && printk_ratelimit()) { 497 printk(KERN_INFO 498 "%s[%d] bad frame in %s frame:%p ip:%lx sp:%lx orax:%lx", 499 me->comm, me->pid, where, frame, 500 regs->ip, regs->sp, regs->orig_ax); 501 print_vma_addr(" in ", regs->ip); 502 printk(KERN_CONT "\n"); 503 } 504 505 force_sig(SIGSEGV, me); 506 } 507