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