arch/x86_64/kernel/signal.c

   1 /*
   2  *  linux/arch/x86_64/kernel/signal.c
   3  *
   4  *  Copyright (C) 1991, 1992  Linus Torvalds
   5  *  Copyright (C) 2000, 2001, 2002 Andi Kleen SuSE Labs
   6  *
   7  *  1997-11-28  Modified for POSIX.1b signals by Richard Henderson
   8  *  2000-06-20  Pentium III FXSR, SSE support by Gareth Hughes
   9  *  2000-2002   x86-64 support by Andi Kleen
  10  */
  11
  12 #include <linux/sched.h>
  13 #include <linux/mm.h>
  14 #include <linux/smp.h>
  15 #include <linux/smp_lock.h>
  16 #include <linux/kernel.h>
  17 #include <linux/signal.h>
  18 #include <linux/errno.h>
  19 #include <linux/wait.h>
  20 #include <linux/ptrace.h>
  21 #include <linux/unistd.h>
  22 #include <linux/stddef.h>
  23 #include <linux/personality.h>
  24 #include <linux/compiler.h>
  25 #include <asm/ucontext.h>
  26 #include <asm/uaccess.h>
  27 #include <asm/i387.h>
  28 #include <asm/proto.h>
  29 #include <asm/ia32_unistd.h>
  30
  31 /* #define DEBUG_SIG 1 */
  32
  33 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
  34
  35 int ia32_setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
  36                sigset_t *set, struct pt_regs * regs);
  37 int ia32_setup_frame(int sig, struct k_sigaction *ka,
  38             sigset_t *set, struct pt_regs * regs);
  39
  40 asmlinkage long
  41 sys_rt_sigsuspend(sigset_t __user *unewset, size_t sigsetsize, struct pt_regs *regs)
  42 {
  43         sigset_t saveset, newset;
  44
  45         /* XXX: Don't preclude handling different sized sigset_t's.  */
  46         if (sigsetsize != sizeof(sigset_t))
  47                 return -EINVAL;
  48
  49         if (copy_from_user(&newset, unewset, sizeof(newset)))
  50                 return -EFAULT;
  51         sigdelsetmask(&newset, ~_BLOCKABLE);
  52
  53         spin_lock_irq(&current->sighand->siglock);
  54         saveset = current->blocked;
  55         current->blocked = newset;
  56         recalc_sigpending();
  57         spin_unlock_irq(&current->sighand->siglock);
  58 #ifdef DEBUG_SIG
  59         printk("rt_sigsuspend savset(%lx) newset(%lx) regs(%p) rip(%lx)\n",
  60                 saveset, newset, regs, regs->rip);
  61 #endif
  62         regs->rax = -EINTR;
  63         while (1) {
  64                 current->state = TASK_INTERRUPTIBLE;
  65                 schedule();
  66                 if (do_signal(regs, &saveset))
  67                         return -EINTR;
  68         }
  69 }
  70
  71 asmlinkage long
  72 sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss,
  73                 struct pt_regs *regs)
  74 {
  75         return do_sigaltstack(uss, uoss, regs->rsp);
  76 }
  77
  78
  79 /*
  80  * Do a signal return; undo the signal stack.
  81  */
  82
  83 struct rt_sigframe
  84 {
  85         char __user *pretcode;
  86         struct ucontext uc;
  87         struct siginfo info;
  88 };
  89
  90 static int
  91 restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc, unsigned long *prax)
  92 {
  93         unsigned int err = 0;
  94
  95         /* Always make any pending restarted system calls return -EINTR */
  96         current_thread_info()->restart_block.fn = do_no_restart_syscall;
  97
  98 #define COPY(x)         err |= __get_user(regs->x, &sc->x)
  99
 100         COPY(rdi); COPY(rsi); COPY(rbp); COPY(rsp); COPY(rbx);
 101         COPY(rdx); COPY(rcx); COPY(rip);
 102         COPY(r8);
 103         COPY(r9);
 104         COPY(r10);
 105         COPY(r11);
 106         COPY(r12);
 107         COPY(r13);
 108         COPY(r14);
 109         COPY(r15);
 110
 111         /* Kernel saves and restores only the CS segment register on signals,
 112          * which is the bare minimum needed to allow mixed 32/64-bit code.
 113          * App's signal handler can save/restore other segments if needed. */
 114         {
 115                 unsigned cs;
 116                 err |= __get_user(cs, &sc->cs);
 117                 regs->cs = cs | 3;      /* Force into user mode */
 118         }
 119
 120         {
 121                 unsigned int tmpflags;
 122                 err |= __get_user(tmpflags, &sc->eflags);
 123                 regs->eflags = (regs->eflags & ~0x40DD5) | (tmpflags & 0x40DD5);
 124                 regs->orig_rax = -1;            /* disable syscall checks */
 125         }
 126
 127         {
 128                 struct _fpstate __user * buf;
 129                 err |= __get_user(buf, &sc->fpstate);
 130
 131                 if (buf) {
 132                         if (!access_ok(VERIFY_READ, buf, sizeof(*buf)))
 133                                 goto badframe;
 134                         err |= restore_i387(buf);
 135                 } else {
 136                         struct task_struct *me = current;
 137                         if (used_math()) {
 138                                 clear_fpu(me);
 139                                 clear_used_math();
 140                         }
 141                 }
 142         }
 143
 144         err |= __get_user(*prax, &sc->rax);
 145         return err;
 146
 147 badframe:
 148         return 1;
 149 }
 150
 151 asmlinkage long sys_rt_sigreturn(struct pt_regs *regs)
 152 {
 153         struct rt_sigframe __user *frame;
 154         sigset_t set;
 155         unsigned long eax;
 156
 157         frame = (struct rt_sigframe __user *)(regs->rsp - 8);
 158         if (!access_ok(VERIFY_READ, frame, sizeof(*frame))) {
 159                 goto badframe;
 160         }
 161         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set))) {
 162                 goto badframe;
 163         }
 164
 165         sigdelsetmask(&set, ~_BLOCKABLE);
 166         spin_lock_irq(&current->sighand->siglock);
 167         current->blocked = set;
 168         recalc_sigpending();
 169         spin_unlock_irq(&current->sighand->siglock);
 170
 171         if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &eax))
 172                 goto badframe;
 173
 174 #ifdef DEBUG_SIG
 175         printk("%d sigreturn rip:%lx rsp:%lx frame:%p rax:%lx\n",current->pid,regs.rip,regs.rsp,frame,eax);
 176 #endif
 177
 178         if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->rsp) == -EFAULT)
 179                 goto badframe;
 180
 181         return eax;
 182
 183 badframe:
 184         signal_fault(regs,frame,"sigreturn");
 185         return 0;
 186 }
 187
 188 /*
 189  * Set up a signal frame.
 190  */
 191
 192 static inline int
 193 setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs, unsigned long mask, struct task_struct *me)
 194 {
 195         int err = 0;
 196
 197         err |= __put_user(regs->cs, &sc->cs);
 198         err |= __put_user(0, &sc->gs);
 199         err |= __put_user(0, &sc->fs);
 200
 201         err |= __put_user(regs->rdi, &sc->rdi);
 202         err |= __put_user(regs->rsi, &sc->rsi);
 203         err |= __put_user(regs->rbp, &sc->rbp);
 204         err |= __put_user(regs->rsp, &sc->rsp);
 205         err |= __put_user(regs->rbx, &sc->rbx);
 206         err |= __put_user(regs->rdx, &sc->rdx);
 207         err |= __put_user(regs->rcx, &sc->rcx);
 208         err |= __put_user(regs->rax, &sc->rax);
 209         err |= __put_user(regs->r8, &sc->r8);
 210         err |= __put_user(regs->r9, &sc->r9);
 211         err |= __put_user(regs->r10, &sc->r10);
 212         err |= __put_user(regs->r11, &sc->r11);
 213         err |= __put_user(regs->r12, &sc->r12);
 214         err |= __put_user(regs->r13, &sc->r13);
 215         err |= __put_user(regs->r14, &sc->r14);
 216         err |= __put_user(regs->r15, &sc->r15);
 217         err |= __put_user(me->thread.trap_no, &sc->trapno);
 218         err |= __put_user(me->thread.error_code, &sc->err);
 219         err |= __put_user(regs->rip, &sc->rip);
 220         err |= __put_user(regs->eflags, &sc->eflags);
 221         err |= __put_user(mask, &sc->oldmask);
 222         err |= __put_user(me->thread.cr2, &sc->cr2);
 223
 224         return err;
 225 }
 226
 227 /*
 228  * Determine which stack to use..
 229  */
 230
 231 static void __user *
 232 get_stack(struct k_sigaction *ka, struct pt_regs *regs, unsigned long size)
 233 {
 234         unsigned long rsp;
 235
 236         /* Default to using normal stack - redzone*/
 237         rsp = regs->rsp - 128;
 238
 239         /* This is the X/Open sanctioned signal stack switching.  */
 240         if (ka->sa.sa_flags & SA_ONSTACK) {
 241                 if (sas_ss_flags(rsp) == 0)
 242                         rsp = current->sas_ss_sp + current->sas_ss_size;
 243         }
 244
 245         return (void __user *)round_down(rsp - size, 16);
 246 }
 247
 248 static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 249                            sigset_t *set, struct pt_regs * regs)
 250 {
 251         struct rt_sigframe __user *frame;
 252         struct _fpstate __user *fp = NULL;
 253         int err = 0;
 254         struct task_struct *me = current;
 255
 256         if (used_math()) {
 257                 fp = get_stack(ka, regs, sizeof(struct _fpstate));
 258                 frame = (void __user *)round_down(
 259                         (unsigned long)fp - sizeof(struct rt_sigframe), 16) - 8;
 260
 261                 if (!access_ok(VERIFY_WRITE, fp, sizeof(struct _fpstate)))
 262                         goto give_sigsegv;
 263
 264                 if (save_i387(fp) < 0)
 265                         err |= -1;
 266         } else
 267                 frame = get_stack(ka, regs, sizeof(struct rt_sigframe)) - 8;
 268
 269         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 270                 goto give_sigsegv;
 271
 272         if (ka->sa.sa_flags & SA_SIGINFO) {
 273                 err |= copy_siginfo_to_user(&frame->info, info);
 274                 if (err)
 275                         goto give_sigsegv;
 276         }
 277
 278         /* Create the ucontext.  */
 279         err |= __put_user(0, &frame->uc.uc_flags);
 280         err |= __put_user(0, &frame->uc.uc_link);
 281         err |= __put_user(me->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
 282         err |= __put_user(sas_ss_flags(regs->rsp),
 283                           &frame->uc.uc_stack.ss_flags);
 284         err |= __put_user(me->sas_ss_size, &frame->uc.uc_stack.ss_size);
 285         err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, set->sig[0], me);
 286         err |= __put_user(fp, &frame->uc.uc_mcontext.fpstate);
 287         if (sizeof(*set) == 16) {
 288                 __put_user(set->sig[0], &frame->uc.uc_sigmask.sig[0]);
 289                 __put_user(set->sig[1], &frame->uc.uc_sigmask.sig[1]);
 290         } else
 291                 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 292
 293         /* Set up to return from userspace.  If provided, use a stub
 294            already in userspace.  */
 295         /* x86-64 should always use SA_RESTORER. */
 296         if (ka->sa.sa_flags & SA_RESTORER) {
 297                 err |= __put_user(ka->sa.sa_restorer, &frame->pretcode);
 298         } else {
 299                 /* could use a vstub here */
 300                 goto give_sigsegv;
 301         }
 302
 303         if (err)
 304                 goto give_sigsegv;
 305
 306 #ifdef DEBUG_SIG
 307         printk("%d old rip %lx old rsp %lx old rax %lx\n", current->pid,regs->rip,regs->rsp,regs->rax);
 308 #endif
 309
 310         /* Set up registers for signal handler */
 311         {
 312                 struct exec_domain *ed = current_thread_info()->exec_domain;
 313                 if (unlikely(ed && ed->signal_invmap && sig < 32))
 314                         sig = ed->signal_invmap[sig];
 315         }
 316         regs->rdi = sig;
 317         /* In case the signal handler was declared without prototypes */
 318         regs->rax = 0;
 319
 320         /* This also works for non SA_SIGINFO handlers because they expect the
 321            next argument after the signal number on the stack. */
 322         regs->rsi = (unsigned long)&frame->info;
 323         regs->rdx = (unsigned long)&frame->uc;
 324         regs->rip = (unsigned long) ka->sa.sa_handler;
 325
 326         regs->rsp = (unsigned long)frame;
 327
 328         /* Set up the CS register to run signal handlers in 64-bit mode,
 329            even if the handler happens to be interrupting 32-bit code. */
 330         regs->cs = __USER_CS;
 331
 332         /* This, by contrast, has nothing to do with segment registers -
 333            see include/asm-x86_64/uaccess.h for details. */
 334         set_fs(USER_DS);
 335
 336         regs->eflags &= ~TF_MASK;
 337         if (test_thread_flag(TIF_SINGLESTEP))
 338                 ptrace_notify(SIGTRAP);
 339 #ifdef DEBUG_SIG
 340         printk("SIG deliver (%s:%d): sp=%p pc=%p ra=%p\n",
 341                 current->comm, current->pid, frame, regs->rip, frame->pretcode);
 342 #endif
 343
 344         return 1;
 345
 346 give_sigsegv:
 347         force_sigsegv(sig, current);
 348         return 0;
 349 }
 350
 351 /*
 352  * OK, we're invoking a handler
 353  */
 354
 355 static int
 356 handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka,
 357                 sigset_t *oldset, struct pt_regs *regs)
 358 {
 359         int ret;
 360
 361 #ifdef DEBUG_SIG
 362         printk("handle_signal pid:%d sig:%lu rip:%lx rsp:%lx regs=%p\n",
 363                 current->pid, sig,
 364                 regs->rip, regs->rsp, regs);
 365 #endif
 366
 367         /* Are we from a system call? */
 368         if ((long)regs->orig_rax >= 0) {
 369                 /* If so, check system call restarting.. */
 370                 switch (regs->rax) {
 371                         case -ERESTART_RESTARTBLOCK:
 372                         case -ERESTARTNOHAND:
 373                                 regs->rax = -EINTR;
 374                                 break;
 375
 376                         case -ERESTARTSYS:
 377                                 if (!(ka->sa.sa_flags & SA_RESTART)) {
 378                                         regs->rax = -EINTR;
 379                                         break;
 380                                 }
 381                                 /* fallthrough */
 382                         case -ERESTARTNOINTR:
 383                                 regs->rax = regs->orig_rax;
 384                                 regs->rip -= 2;
 385                                 break;
 386                 }
 387         }
 388
 389         /*
 390          * If TF is set due to a debugger (PT_DTRACE), clear the TF
 391          * flag so that register information in the sigcontext is
 392          * correct.
 393          */
 394         if (unlikely(regs->eflags & TF_MASK)) {
 395                 if (likely(current->ptrace & PT_DTRACE)) {
 396                         current->ptrace &= ~PT_DTRACE;
 397                         regs->eflags &= ~TF_MASK;
 398                 }
 399         }
 400
 401 #ifdef CONFIG_IA32_EMULATION
 402         if (test_thread_flag(TIF_IA32)) {
 403                 if (ka->sa.sa_flags & SA_SIGINFO)
 404                         ret = ia32_setup_rt_frame(sig, ka, info, oldset, regs);
 405                 else
 406                         ret = ia32_setup_frame(sig, ka, oldset, regs);
 407         } else
 408 #endif
 409         ret = setup_rt_frame(sig, ka, info, oldset, regs);
 410
 411         if (ret) {
 412                 spin_lock_irq(&current->sighand->siglock);
 413                 sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
 414                 if (!(ka->sa.sa_flags & SA_NODEFER))
 415                         sigaddset(&current->blocked,sig);
 416                 recalc_sigpending();
 417                 spin_unlock_irq(&current->sighand->siglock);
 418         }
 419
 420         return ret;
 421 }
 422
 423 /*
 424  * Note that 'init' is a special process: it doesn't get signals it doesn't
 425  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 426  * mistake.
 427  */
 428 int do_signal(struct pt_regs *regs, sigset_t *oldset)
 429 {
 430         struct k_sigaction ka;
 431         siginfo_t info;
 432         int signr;
 433
 434         /*
 435          * We want the common case to go fast, which
 436          * is why we may in certain cases get here from
 437          * kernel mode. Just return without doing anything
 438          * if so.
 439          */
 440         if (!user_mode(regs))
 441                 return 1;
 442
 443         if (!oldset)
 444                 oldset = &current->blocked;
 445
 446         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 447         if (signr > 0) {
 448                 /* Reenable any watchpoints before delivering the
 449                  * signal to user space. The processor register will
 450                  * have been cleared if the watchpoint triggered
 451                  * inside the kernel.
 452                  */
 453                 if (current->thread.debugreg7)
 454                         set_debugreg(current->thread.debugreg7, 7);
 455
 456                 /* Whee!  Actually deliver the signal.  */
 457                 return handle_signal(signr, &info, &ka, oldset, regs);
 458         }
 459
 460         /* Did we come from a system call? */
 461         if ((long)regs->orig_rax >= 0) {
 462                 /* Restart the system call - no handlers present */
 463                 long res = regs->rax;
 464                 if (res == -ERESTARTNOHAND ||
 465                     res == -ERESTARTSYS ||
 466                     res == -ERESTARTNOINTR) {
 467                         regs->rax = regs->orig_rax;
 468                         regs->rip -= 2;
 469                 }
 470                 if (regs->rax == (unsigned long)-ERESTART_RESTARTBLOCK) {
 471                         regs->rax = test_thread_flag(TIF_IA32) ?
 472                                         __NR_ia32_restart_syscall :
 473                                         __NR_restart_syscall;
 474                         regs->rip -= 2;
 475                 }
 476         }
 477         return 0;
 478 }
 479
 480 void do_notify_resume(struct pt_regs *regs, sigset_t *oldset, __u32 thread_info_flags)
 481 {
 482 #ifdef DEBUG_SIG
 483         printk("do_notify_resume flags:%x rip:%lx rsp:%lx caller:%lx pending:%lx\n",
 484                thread_info_flags, regs->rip, regs->rsp, __builtin_return_address(0),signal_pending(current));
 485 #endif
 486
 487         /* Pending single-step? */
 488         if (thread_info_flags & _TIF_SINGLESTEP) {
 489                 regs->eflags |= TF_MASK;
 490                 clear_thread_flag(TIF_SINGLESTEP);
 491         }
 492
 493         /* deal with pending signal delivery */
 494         if (thread_info_flags & _TIF_SIGPENDING)
 495                 do_signal(regs,oldset);
 496 }
 497
 498 void signal_fault(struct pt_regs *regs, void __user *frame, char *where)
 499 {
 500         struct task_struct *me = current;
 501         if (exception_trace)
 502                 printk("%s[%d] bad frame in %s frame:%p rip:%lx rsp:%lx orax:%lx\n",
 503                me->comm,me->pid,where,frame,regs->rip,regs->rsp,regs->orig_rax);
 504
 505         force_sig(SIGSEGV, me);
 506 }