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 void __user *buf; 73 unsigned int tmpflags; 74 unsigned int err = 0; 75 76 /* Always make any pending restarted system calls return -EINTR */ 77 current_thread_info()->restart_block.fn = do_no_restart_syscall; 78 79 COPY(di); COPY(si); COPY(bp); COPY(sp); COPY(bx); 80 COPY(dx); COPY(cx); COPY(ip); 81 COPY(r8); 82 COPY(r9); 83 COPY(r10); 84 COPY(r11); 85 COPY(r12); 86 COPY(r13); 87 COPY(r14); 88 COPY(r15); 89 90 /* Kernel saves and restores only the CS segment register on signals, 91 * which is the bare minimum needed to allow mixed 32/64-bit code. 92 * App's signal handler can save/restore other segments if needed. */ 93 COPY_SEG_STRICT(cs); 94 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 err |= __get_user(buf, &sc->fpstate); 100 err |= restore_i387_xstate(buf); 101 102 err |= __get_user(*pax, &sc->ax); 103 return err; 104 } 105 106 static long do_rt_sigreturn(struct pt_regs *regs) 107 { 108 struct rt_sigframe __user *frame; 109 unsigned long ax; 110 sigset_t set; 111 112 frame = (struct rt_sigframe __user *)(regs->sp - sizeof(long)); 113 if (!access_ok(VERIFY_READ, frame, sizeof(*frame))) 114 goto badframe; 115 if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set))) 116 goto badframe; 117 118 sigdelsetmask(&set, ~_BLOCKABLE); 119 spin_lock_irq(¤t->sighand->siglock); 120 current->blocked = set; 121 recalc_sigpending(); 122 spin_unlock_irq(¤t->sighand->siglock); 123 124 if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &ax)) 125 goto badframe; 126 127 if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->sp) == -EFAULT) 128 goto badframe; 129 130 return ax; 131 132 badframe: 133 signal_fault(regs, frame, "rt_sigreturn"); 134 return 0; 135 } 136 137 asmlinkage long sys_rt_sigreturn(struct pt_regs *regs) 138 { 139 return do_rt_sigreturn(regs); 140 } 141 142 /* 143 * Set up a signal frame. 144 */ 145 146 static inline int 147 setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs, 148 unsigned long mask, struct task_struct *me) 149 { 150 int err = 0; 151 152 err |= __put_user(regs->cs, &sc->cs); 153 err |= __put_user(0, &sc->gs); 154 err |= __put_user(0, &sc->fs); 155 156 err |= __put_user(regs->di, &sc->di); 157 err |= __put_user(regs->si, &sc->si); 158 err |= __put_user(regs->bp, &sc->bp); 159 err |= __put_user(regs->sp, &sc->sp); 160 err |= __put_user(regs->bx, &sc->bx); 161 err |= __put_user(regs->dx, &sc->dx); 162 err |= __put_user(regs->cx, &sc->cx); 163 err |= __put_user(regs->ax, &sc->ax); 164 err |= __put_user(regs->r8, &sc->r8); 165 err |= __put_user(regs->r9, &sc->r9); 166 err |= __put_user(regs->r10, &sc->r10); 167 err |= __put_user(regs->r11, &sc->r11); 168 err |= __put_user(regs->r12, &sc->r12); 169 err |= __put_user(regs->r13, &sc->r13); 170 err |= __put_user(regs->r14, &sc->r14); 171 err |= __put_user(regs->r15, &sc->r15); 172 err |= __put_user(me->thread.trap_no, &sc->trapno); 173 err |= __put_user(me->thread.error_code, &sc->err); 174 err |= __put_user(regs->ip, &sc->ip); 175 err |= __put_user(regs->flags, &sc->flags); 176 err |= __put_user(mask, &sc->oldmask); 177 err |= __put_user(me->thread.cr2, &sc->cr2); 178 179 return err; 180 } 181 182 /* 183 * Determine which stack to use.. 184 */ 185 186 static void __user * 187 get_stack(struct k_sigaction *ka, struct pt_regs *regs, unsigned long size) 188 { 189 unsigned long sp; 190 191 /* Default to using normal stack - redzone*/ 192 sp = regs->sp - 128; 193 194 /* This is the X/Open sanctioned signal stack switching. */ 195 if (ka->sa.sa_flags & SA_ONSTACK) { 196 if (sas_ss_flags(sp) == 0) 197 sp = current->sas_ss_sp + current->sas_ss_size; 198 } 199 200 return (void __user *)round_down(sp - size, 64); 201 } 202 203 static int __setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info, 204 sigset_t *set, struct pt_regs *regs) 205 { 206 struct rt_sigframe __user *frame; 207 void __user *fp = NULL; 208 int err = 0; 209 struct task_struct *me = current; 210 211 if (used_math()) { 212 fp = get_stack(ka, regs, sig_xstate_size); 213 frame = (void __user *)round_down( 214 (unsigned long)fp - sizeof(struct rt_sigframe), 16) - 8; 215 216 if (save_i387_xstate(fp) < 0) 217 return -EFAULT; 218 } else 219 frame = get_stack(ka, regs, sizeof(struct rt_sigframe)) - 8; 220 221 if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame))) 222 return -EFAULT; 223 224 if (ka->sa.sa_flags & SA_SIGINFO) { 225 if (copy_siginfo_to_user(&frame->info, info)) 226 return -EFAULT; 227 } 228 229 /* Create the ucontext. */ 230 if (cpu_has_xsave) 231 err |= __put_user(UC_FP_XSTATE, &frame->uc.uc_flags); 232 else 233 err |= __put_user(0, &frame->uc.uc_flags); 234 err |= __put_user(0, &frame->uc.uc_link); 235 err |= __put_user(me->sas_ss_sp, &frame->uc.uc_stack.ss_sp); 236 err |= __put_user(sas_ss_flags(regs->sp), 237 &frame->uc.uc_stack.ss_flags); 238 err |= __put_user(me->sas_ss_size, &frame->uc.uc_stack.ss_size); 239 err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, set->sig[0], me); 240 err |= __put_user(fp, &frame->uc.uc_mcontext.fpstate); 241 if (sizeof(*set) == 16) { 242 __put_user(set->sig[0], &frame->uc.uc_sigmask.sig[0]); 243 __put_user(set->sig[1], &frame->uc.uc_sigmask.sig[1]); 244 } else 245 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)); 246 247 /* Set up to return from userspace. If provided, use a stub 248 already in userspace. */ 249 /* x86-64 should always use SA_RESTORER. */ 250 if (ka->sa.sa_flags & SA_RESTORER) { 251 err |= __put_user(ka->sa.sa_restorer, &frame->pretcode); 252 } else { 253 /* could use a vstub here */ 254 return -EFAULT; 255 } 256 257 if (err) 258 return -EFAULT; 259 260 /* Set up registers for signal handler */ 261 regs->di = sig; 262 /* In case the signal handler was declared without prototypes */ 263 regs->ax = 0; 264 265 /* This also works for non SA_SIGINFO handlers because they expect the 266 next argument after the signal number on the stack. */ 267 regs->si = (unsigned long)&frame->info; 268 regs->dx = (unsigned long)&frame->uc; 269 regs->ip = (unsigned long) ka->sa.sa_handler; 270 271 regs->sp = (unsigned long)frame; 272 273 /* Set up the CS register to run signal handlers in 64-bit mode, 274 even if the handler happens to be interrupting 32-bit code. */ 275 regs->cs = __USER_CS; 276 277 return 0; 278 } 279 280 /* 281 * OK, we're invoking a handler 282 */ 283 static int signr_convert(int sig) 284 { 285 return sig; 286 } 287 288 #ifdef CONFIG_IA32_EMULATION 289 #define is_ia32 test_thread_flag(TIF_IA32) 290 #else 291 #define is_ia32 0 292 #endif 293 294 static int 295 setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info, 296 sigset_t *set, struct pt_regs *regs) 297 { 298 int usig = signr_convert(sig); 299 int ret; 300 301 /* Set up the stack frame */ 302 if (is_ia32) { 303 if (ka->sa.sa_flags & SA_SIGINFO) 304 ret = ia32_setup_rt_frame(usig, ka, info, set, regs); 305 else 306 ret = ia32_setup_frame(usig, ka, set, regs); 307 } else 308 ret = __setup_rt_frame(sig, ka, info, set, regs); 309 310 if (ret) { 311 force_sigsegv(sig, current); 312 return -EFAULT; 313 } 314 315 return ret; 316 } 317 318 static int 319 handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka, 320 sigset_t *oldset, struct pt_regs *regs) 321 { 322 int ret; 323 324 /* Are we from a system call? */ 325 if (syscall_get_nr(current, regs) >= 0) { 326 /* If so, check system call restarting.. */ 327 switch (syscall_get_error(current, regs)) { 328 case -ERESTART_RESTARTBLOCK: 329 case -ERESTARTNOHAND: 330 regs->ax = -EINTR; 331 break; 332 333 case -ERESTARTSYS: 334 if (!(ka->sa.sa_flags & SA_RESTART)) { 335 regs->ax = -EINTR; 336 break; 337 } 338 /* fallthrough */ 339 case -ERESTARTNOINTR: 340 regs->ax = regs->orig_ax; 341 regs->ip -= 2; 342 break; 343 } 344 } 345 346 /* 347 * If TF is set due to a debugger (TIF_FORCED_TF), clear the TF 348 * flag so that register information in the sigcontext is correct. 349 */ 350 if (unlikely(regs->flags & X86_EFLAGS_TF) && 351 likely(test_and_clear_thread_flag(TIF_FORCED_TF))) 352 regs->flags &= ~X86_EFLAGS_TF; 353 354 ret = setup_rt_frame(sig, ka, info, oldset, regs); 355 356 if (ret) 357 return ret; 358 359 #ifdef CONFIG_X86_64 360 /* 361 * This has nothing to do with segment registers, 362 * despite the name. This magic affects uaccess.h 363 * macros' behavior. Reset it to the normal setting. 364 */ 365 set_fs(USER_DS); 366 #endif 367 368 /* 369 * Clear the direction flag as per the ABI for function entry. 370 */ 371 regs->flags &= ~X86_EFLAGS_DF; 372 373 /* 374 * Clear TF when entering the signal handler, but 375 * notify any tracer that was single-stepping it. 376 * The tracer may want to single-step inside the 377 * handler too. 378 */ 379 regs->flags &= ~X86_EFLAGS_TF; 380 381 spin_lock_irq(¤t->sighand->siglock); 382 sigorsets(¤t->blocked, ¤t->blocked, &ka->sa.sa_mask); 383 if (!(ka->sa.sa_flags & SA_NODEFER)) 384 sigaddset(¤t->blocked, sig); 385 recalc_sigpending(); 386 spin_unlock_irq(¤t->sighand->siglock); 387 388 tracehook_signal_handler(sig, info, ka, regs, 389 test_thread_flag(TIF_SINGLESTEP)); 390 391 return 0; 392 } 393 394 #define NR_restart_syscall \ 395 test_thread_flag(TIF_IA32) ? __NR_ia32_restart_syscall : __NR_restart_syscall 396 /* 397 * Note that 'init' is a special process: it doesn't get signals it doesn't 398 * want to handle. Thus you cannot kill init even with a SIGKILL even by 399 * mistake. 400 */ 401 static void do_signal(struct pt_regs *regs) 402 { 403 struct k_sigaction ka; 404 siginfo_t info; 405 int signr; 406 sigset_t *oldset; 407 408 /* 409 * We want the common case to go fast, which is why we may in certain 410 * cases get here from kernel mode. Just return without doing anything 411 * if so. 412 * X86_32: vm86 regs switched out by assembly code before reaching 413 * here, so testing against kernel CS suffices. 414 */ 415 if (!user_mode(regs)) 416 return; 417 418 if (current_thread_info()->status & TS_RESTORE_SIGMASK) 419 oldset = ¤t->saved_sigmask; 420 else 421 oldset = ¤t->blocked; 422 423 signr = get_signal_to_deliver(&info, &ka, regs, NULL); 424 if (signr > 0) { 425 /* 426 * Re-enable any watchpoints before delivering the 427 * signal to user space. The processor register will 428 * have been cleared if the watchpoint triggered 429 * inside the kernel. 430 */ 431 if (current->thread.debugreg7) 432 set_debugreg(current->thread.debugreg7, 7); 433 434 /* Whee! Actually deliver the signal. */ 435 if (handle_signal(signr, &info, &ka, oldset, regs) == 0) { 436 /* 437 * A signal was successfully delivered; the saved 438 * sigmask will have been stored in the signal frame, 439 * and will be restored by sigreturn, so we can simply 440 * clear the TS_RESTORE_SIGMASK flag. 441 */ 442 current_thread_info()->status &= ~TS_RESTORE_SIGMASK; 443 } 444 return; 445 } 446 447 /* Did we come from a system call? */ 448 if (syscall_get_nr(current, regs) >= 0) { 449 /* Restart the system call - no handlers present */ 450 switch (syscall_get_error(current, regs)) { 451 case -ERESTARTNOHAND: 452 case -ERESTARTSYS: 453 case -ERESTARTNOINTR: 454 regs->ax = regs->orig_ax; 455 regs->ip -= 2; 456 break; 457 458 case -ERESTART_RESTARTBLOCK: 459 regs->ax = NR_restart_syscall; 460 regs->ip -= 2; 461 break; 462 } 463 } 464 465 /* 466 * If there's no signal to deliver, we just put the saved sigmask 467 * back. 468 */ 469 if (current_thread_info()->status & TS_RESTORE_SIGMASK) { 470 current_thread_info()->status &= ~TS_RESTORE_SIGMASK; 471 sigprocmask(SIG_SETMASK, ¤t->saved_sigmask, NULL); 472 } 473 } 474 475 /* 476 * notification of userspace execution resumption 477 * - triggered by the TIF_WORK_MASK flags 478 */ 479 void 480 do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags) 481 { 482 #if defined(CONFIG_X86_64) && defined(CONFIG_X86_MCE) 483 /* notify userspace of pending MCEs */ 484 if (thread_info_flags & _TIF_MCE_NOTIFY) 485 mce_notify_user(); 486 #endif /* CONFIG_X86_64 && CONFIG_X86_MCE */ 487 488 /* deal with pending signal delivery */ 489 if (thread_info_flags & _TIF_SIGPENDING) 490 do_signal(regs); 491 492 if (thread_info_flags & _TIF_NOTIFY_RESUME) { 493 clear_thread_flag(TIF_NOTIFY_RESUME); 494 tracehook_notify_resume(regs); 495 } 496 497 #ifdef CONFIG_X86_32 498 clear_thread_flag(TIF_IRET); 499 #endif /* CONFIG_X86_32 */ 500 } 501 502 void signal_fault(struct pt_regs *regs, void __user *frame, char *where) 503 { 504 struct task_struct *me = current; 505 506 if (show_unhandled_signals && printk_ratelimit()) { 507 printk(KERN_INFO 508 "%s[%d] bad frame in %s frame:%p ip:%lx sp:%lx orax:%lx", 509 me->comm, me->pid, where, frame, 510 regs->ip, regs->sp, regs->orig_ax); 511 print_vma_addr(" in ", regs->ip); 512 printk(KERN_CONT "\n"); 513 } 514 515 force_sig(SIGSEGV, me); 516 } 517