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->rsp); 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(rdi); COPY(rsi); COPY(rbp); COPY(rsp); COPY(rbx); 68 COPY(rdx); COPY(rcx); COPY(rip); 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->eflags); 90 regs->eflags = (regs->eflags & ~0x40DD5) | (tmpflags & 0x40DD5); 91 regs->orig_rax = -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->rax); 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 eax; 123 124 frame = (struct rt_sigframe __user *)(regs->rsp - 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, &eax)) 139 goto badframe; 140 141 #ifdef DEBUG_SIG 142 printk("%d sigreturn rip:%lx rsp:%lx frame:%p rax:%lx\n",current->pid,regs->rip,regs->rsp,frame,eax); 143 #endif 144 145 if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->rsp) == -EFAULT) 146 goto badframe; 147 148 return eax; 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->rdi, &sc->rdi); 169 err |= __put_user(regs->rsi, &sc->rsi); 170 err |= __put_user(regs->rbp, &sc->rbp); 171 err |= __put_user(regs->rsp, &sc->rsp); 172 err |= __put_user(regs->rbx, &sc->rbx); 173 err |= __put_user(regs->rdx, &sc->rdx); 174 err |= __put_user(regs->rcx, &sc->rcx); 175 err |= __put_user(regs->rax, &sc->rax); 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->rip, &sc->rip); 187 err |= __put_user(regs->eflags, &sc->eflags); 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 rsp; 202 203 /* Default to using normal stack - redzone*/ 204 rsp = regs->rsp - 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(rsp) == 0) 209 rsp = current->sas_ss_sp + current->sas_ss_size; 210 } 211 212 return (void __user *)round_down(rsp - 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->rsp), 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 rip %lx old rsp %lx old rax %lx\n", current->pid,regs->rip,regs->rsp,regs->rax); 275 #endif 276 277 /* Set up registers for signal handler */ 278 regs->rdi = sig; 279 /* In case the signal handler was declared without prototypes */ 280 regs->rax = 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->rsi = (unsigned long)&frame->info; 285 regs->rdx = (unsigned long)&frame->uc; 286 regs->rip = (unsigned long) ka->sa.sa_handler; 287 288 regs->rsp = (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->eflags &= ~TF_MASK; 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->rip, 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 rip:%lx rsp:%lx regs=%p\n", 325 current->pid, sig, 326 regs->rip, regs->rsp, regs); 327 #endif 328 329 /* Are we from a system call? */ 330 if ((long)regs->orig_rax >= 0) { 331 /* If so, check system call restarting.. */ 332 switch (regs->rax) { 333 case -ERESTART_RESTARTBLOCK: 334 case -ERESTARTNOHAND: 335 regs->rax = -EINTR; 336 break; 337 338 case -ERESTARTSYS: 339 if (!(ka->sa.sa_flags & SA_RESTART)) { 340 regs->rax = -EINTR; 341 break; 342 } 343 /* fallthrough */ 344 case -ERESTARTNOINTR: 345 regs->rax = regs->orig_rax; 346 regs->rip -= 2; 347 break; 348 } 349 } 350 351 /* 352 * If TF is set due to a debugger (PT_DTRACE), clear the TF 353 * flag so that register information in the sigcontext is 354 * correct. 355 */ 356 if (unlikely(regs->eflags & TF_MASK)) { 357 if (likely(current->ptrace & PT_DTRACE)) { 358 current->ptrace &= ~PT_DTRACE; 359 regs->eflags &= ~TF_MASK; 360 } 361 } 362 363 #ifdef CONFIG_IA32_EMULATION 364 if (test_thread_flag(TIF_IA32)) { 365 if (ka->sa.sa_flags & SA_SIGINFO) 366 ret = ia32_setup_rt_frame(sig, ka, info, oldset, regs); 367 else 368 ret = ia32_setup_frame(sig, ka, oldset, regs); 369 } else 370 #endif 371 ret = setup_rt_frame(sig, ka, info, oldset, regs); 372 373 if (ret == 0) { 374 spin_lock_irq(¤t->sighand->siglock); 375 sigorsets(¤t->blocked,¤t->blocked,&ka->sa.sa_mask); 376 if (!(ka->sa.sa_flags & SA_NODEFER)) 377 sigaddset(¤t->blocked,sig); 378 recalc_sigpending(); 379 spin_unlock_irq(¤t->sighand->siglock); 380 } 381 382 return ret; 383 } 384 385 /* 386 * Note that 'init' is a special process: it doesn't get signals it doesn't 387 * want to handle. Thus you cannot kill init even with a SIGKILL even by 388 * mistake. 389 */ 390 static void do_signal(struct pt_regs *regs) 391 { 392 struct k_sigaction ka; 393 siginfo_t info; 394 int signr; 395 sigset_t *oldset; 396 397 /* 398 * We want the common case to go fast, which 399 * is why we may in certain cases get here from 400 * kernel mode. Just return without doing anything 401 * if so. 402 */ 403 if (!user_mode(regs)) 404 return; 405 406 if (test_thread_flag(TIF_RESTORE_SIGMASK)) 407 oldset = ¤t->saved_sigmask; 408 else 409 oldset = ¤t->blocked; 410 411 signr = get_signal_to_deliver(&info, &ka, regs, NULL); 412 if (signr > 0) { 413 /* Reenable any watchpoints before delivering the 414 * signal to user space. The processor register will 415 * have been cleared if the watchpoint triggered 416 * inside the kernel. 417 */ 418 if (current->thread.debugreg7) 419 set_debugreg(current->thread.debugreg7, 7); 420 421 /* Whee! Actually deliver the signal. */ 422 if (handle_signal(signr, &info, &ka, oldset, regs) == 0) { 423 /* a signal was successfully delivered; the saved 424 * sigmask will have been stored in the signal frame, 425 * and will be restored by sigreturn, so we can simply 426 * clear the TIF_RESTORE_SIGMASK flag */ 427 clear_thread_flag(TIF_RESTORE_SIGMASK); 428 } 429 return; 430 } 431 432 /* Did we come from a system call? */ 433 if ((long)regs->orig_rax >= 0) { 434 /* Restart the system call - no handlers present */ 435 long res = regs->rax; 436 switch (res) { 437 case -ERESTARTNOHAND: 438 case -ERESTARTSYS: 439 case -ERESTARTNOINTR: 440 regs->rax = regs->orig_rax; 441 regs->rip -= 2; 442 break; 443 case -ERESTART_RESTARTBLOCK: 444 regs->rax = test_thread_flag(TIF_IA32) ? 445 __NR_ia32_restart_syscall : 446 __NR_restart_syscall; 447 regs->rip -= 2; 448 break; 449 } 450 } 451 452 /* if there's no signal to deliver, we just put the saved sigmask 453 back. */ 454 if (test_thread_flag(TIF_RESTORE_SIGMASK)) { 455 clear_thread_flag(TIF_RESTORE_SIGMASK); 456 sigprocmask(SIG_SETMASK, ¤t->saved_sigmask, NULL); 457 } 458 } 459 460 void 461 do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags) 462 { 463 #ifdef DEBUG_SIG 464 printk("do_notify_resume flags:%x rip:%lx rsp:%lx caller:%p pending:%x\n", 465 thread_info_flags, regs->rip, regs->rsp, __builtin_return_address(0),signal_pending(current)); 466 #endif 467 468 /* Pending single-step? */ 469 if (thread_info_flags & _TIF_SINGLESTEP) { 470 regs->eflags |= TF_MASK; 471 clear_thread_flag(TIF_SINGLESTEP); 472 } 473 474 #ifdef CONFIG_X86_MCE 475 /* notify userspace of pending MCEs */ 476 if (thread_info_flags & _TIF_MCE_NOTIFY) 477 mce_notify_user(); 478 #endif /* CONFIG_X86_MCE */ 479 480 /* deal with pending signal delivery */ 481 if (thread_info_flags & (_TIF_SIGPENDING|_TIF_RESTORE_SIGMASK)) 482 do_signal(regs); 483 } 484 485 void signal_fault(struct pt_regs *regs, void __user *frame, char *where) 486 { 487 struct task_struct *me = current; 488 if (show_unhandled_signals && printk_ratelimit()) 489 printk("%s[%d] bad frame in %s frame:%p rip:%lx rsp:%lx orax:%lx\n", 490 me->comm,me->pid,where,frame,regs->rip,regs->rsp,regs->orig_rax); 491 492 force_sig(SIGSEGV, me); 493 } 494