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  *  $Id: signal.c,v 1.18 2001/10/17 22:30:37 ak Exp $
  12  */
  13
  14 #include <linux/sched.h>
  15 #include <linux/mm.h>
  16 #include <linux/smp.h>
  17 #include <linux/smp_lock.h>
  18 #include <linux/kernel.h>
  19 #include <linux/signal.h>
  20 #include <linux/errno.h>
  21 #include <linux/wait.h>
  22 #include <linux/ptrace.h>
  23 #include <linux/unistd.h>
  24 #include <linux/stddef.h>
  25 #include <linux/personality.h>
  26 #include <linux/compiler.h>
  27 #include <asm/ucontext.h>
  28 #include <asm/uaccess.h>
  29 #include <asm/i387.h>
  30 #include <asm/proto.h>
  31
  32 /* #define DEBUG_SIG 1 */
  33
  34 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
  35
  36 void ia32_setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
  37                sigset_t *set, struct pt_regs * regs);
  38 void ia32_setup_frame(int sig, struct k_sigaction *ka,
  39             sigset_t *set, struct pt_regs * regs);
  40
  41 asmlinkage long
  42 sys_rt_sigsuspend(sigset_t __user *unewset, size_t sigsetsize, struct pt_regs *regs)
  43 {
  44         sigset_t saveset, newset;
  45
  46         /* XXX: Don't preclude handling different sized sigset_t's.  */
  47         if (sigsetsize != sizeof(sigset_t))
  48                 return -EINVAL;
  49
  50         if (copy_from_user(&newset, unewset, sizeof(newset)))
  51                 return -EFAULT;
  52         sigdelsetmask(&newset, ~_BLOCKABLE);
  53
  54         spin_lock_irq(&current->sighand->siglock);
  55         saveset = current->blocked;
  56         current->blocked = newset;
  57         recalc_sigpending();
  58         spin_unlock_irq(&current->sighand->siglock);
  59 #ifdef DEBUG_SIG
  60         printk("rt_sigsuspend savset(%lx) newset(%lx) regs(%p) rip(%lx)\n",
  61                 saveset, newset, regs, regs->rip);
  62 #endif
  63         regs->rax = -EINTR;
  64         while (1) {
  65                 current->state = TASK_INTERRUPTIBLE;
  66                 schedule();
  67                 if (do_signal(regs, &saveset))
  68                         return -EINTR;
  69         }
  70 }
  71
  72 asmlinkage long
  73 sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss,
  74                 struct pt_regs *regs)
  75 {
  76         return do_sigaltstack(uss, uoss, regs->rsp);
  77 }
  78
  79
  80 /*
  81  * Do a signal return; undo the signal stack.
  82  */
  83
  84 struct rt_sigframe
  85 {
  86         char __user *pretcode;
  87         struct ucontext uc;
  88         struct siginfo info;
  89 };
  90
  91 static int
  92 restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc, unsigned long *prax)
  93 {
  94         unsigned int err = 0;
  95
  96         /* Always make any pending restarted system calls return -EINTR */
  97         current_thread_info()->restart_block.fn = do_no_restart_syscall;
  98
  99 #define COPY(x)         err |= __get_user(regs->x, &sc->x)
 100
 101         COPY(rdi); COPY(rsi); COPY(rbp); COPY(rsp); COPY(rbx);
 102         COPY(rdx); COPY(rcx); COPY(rip);
 103         COPY(r8);
 104         COPY(r9);
 105         COPY(r10);
 106         COPY(r11);
 107         COPY(r12);
 108         COPY(r13);
 109         COPY(r14);
 110         COPY(r15);
 111
 112         {
 113                 unsigned int tmpflags;
 114                 err |= __get_user(tmpflags, &sc->eflags);
 115                 regs->eflags = (regs->eflags & ~0x40DD5) | (tmpflags & 0x40DD5);
 116                 regs->orig_rax = -1;            /* disable syscall checks */
 117         }
 118
 119         {
 120                 struct _fpstate __user * buf;
 121                 err |= __get_user(buf, &sc->fpstate);
 122
 123                 if (buf) {
 124                         if (!access_ok(VERIFY_READ, buf, sizeof(*buf)))
 125                                 goto badframe;
 126                         err |= restore_i387(buf);
 127                 } else {
 128                         struct task_struct *me = current;
 129                         if (used_math()) {
 130                                 clear_fpu(me);
 131                                 clear_used_math();
 132                         }
 133                 }
 134         }
 135
 136         err |= __get_user(*prax, &sc->rax);
 137         return err;
 138
 139 badframe:
 140         return 1;
 141 }
 142
 143 asmlinkage long sys_rt_sigreturn(struct pt_regs *regs)
 144 {
 145         struct rt_sigframe __user *frame;
 146         sigset_t set;
 147         unsigned long eax;
 148
 149         frame = (struct rt_sigframe __user *)(regs->rsp - 8);
 150         if (!access_ok(VERIFY_READ, frame, sizeof(*frame))) {
 151                 goto badframe;
 152         }
 153         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set))) {
 154                 goto badframe;
 155         }
 156
 157         sigdelsetmask(&set, ~_BLOCKABLE);
 158         spin_lock_irq(&current->sighand->siglock);
 159         current->blocked = set;
 160         recalc_sigpending();
 161         spin_unlock_irq(&current->sighand->siglock);
 162
 163         if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &eax))
 164                 goto badframe;
 165
 166 #ifdef DEBUG_SIG
 167         printk("%d sigreturn rip:%lx rsp:%lx frame:%p rax:%lx\n",current->pid,regs.rip,regs.rsp,frame,eax);
 168 #endif
 169
 170         if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->rsp) == -EFAULT)
 171                 goto badframe;
 172
 173         return eax;
 174
 175 badframe:
 176         signal_fault(regs,frame,"sigreturn");
 177         return 0;
 178 }
 179
 180 /*
 181  * Set up a signal frame.
 182  */
 183
 184 static inline int
 185 setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs, unsigned long mask, struct task_struct *me)
 186 {
 187         int err = 0;
 188
 189         err |= __put_user(0, &sc->gs);
 190         err |= __put_user(0, &sc->fs);
 191
 192         err |= __put_user(regs->rdi, &sc->rdi);
 193         err |= __put_user(regs->rsi, &sc->rsi);
 194         err |= __put_user(regs->rbp, &sc->rbp);
 195         err |= __put_user(regs->rsp, &sc->rsp);
 196         err |= __put_user(regs->rbx, &sc->rbx);
 197         err |= __put_user(regs->rdx, &sc->rdx);
 198         err |= __put_user(regs->rcx, &sc->rcx);
 199         err |= __put_user(regs->rax, &sc->rax);
 200         err |= __put_user(regs->r8, &sc->r8);
 201         err |= __put_user(regs->r9, &sc->r9);
 202         err |= __put_user(regs->r10, &sc->r10);
 203         err |= __put_user(regs->r11, &sc->r11);
 204         err |= __put_user(regs->r12, &sc->r12);
 205         err |= __put_user(regs->r13, &sc->r13);
 206         err |= __put_user(regs->r14, &sc->r14);
 207         err |= __put_user(regs->r15, &sc->r15);
 208         err |= __put_user(me->thread.trap_no, &sc->trapno);
 209         err |= __put_user(me->thread.error_code, &sc->err);
 210         err |= __put_user(regs->rip, &sc->rip);
 211         err |= __put_user(regs->eflags, &sc->eflags);
 212         err |= __put_user(mask, &sc->oldmask);
 213         err |= __put_user(me->thread.cr2, &sc->cr2);
 214
 215         return err;
 216 }
 217
 218 /*
 219  * Determine which stack to use..
 220  */
 221
 222 static void __user *
 223 get_stack(struct k_sigaction *ka, struct pt_regs *regs, unsigned long size)
 224 {
 225         unsigned long rsp;
 226
 227         /* Default to using normal stack - redzone*/
 228         rsp = regs->rsp - 128;
 229
 230         /* This is the X/Open sanctioned signal stack switching.  */
 231         /* RED-PEN: redzone on that stack? */
 232         if (ka->sa.sa_flags & SA_ONSTACK) {
 233                 if (sas_ss_flags(rsp) == 0)
 234                         rsp = current->sas_ss_sp + current->sas_ss_size;
 235         }
 236
 237         return (void __user *)round_down(rsp - size, 16);
 238 }
 239
 240 static void setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 241                            sigset_t *set, struct pt_regs * regs)
 242 {
 243         struct rt_sigframe __user *frame;
 244         struct _fpstate __user *fp = NULL;
 245         int err = 0;
 246         struct task_struct *me = current;
 247
 248         if (used_math()) {
 249                 fp = get_stack(ka, regs, sizeof(struct _fpstate));
 250                 frame = (void __user *)round_down(
 251                         (unsigned long)fp - sizeof(struct rt_sigframe), 16) - 8;
 252
 253                 if (!access_ok(VERIFY_WRITE, fp, sizeof(struct _fpstate)))
 254                         goto give_sigsegv;
 255
 256                 if (save_i387(fp) < 0)
 257                         err |= -1;
 258         } else
 259                 frame = get_stack(ka, regs, sizeof(struct rt_sigframe)) - 8;
 260
 261         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 262                 goto give_sigsegv;
 263
 264         if (ka->sa.sa_flags & SA_SIGINFO) {
 265                 err |= copy_siginfo_to_user(&frame->info, info);
 266                 if (err)
 267                         goto give_sigsegv;
 268         }
 269
 270         /* Create the ucontext.  */
 271         err |= __put_user(0, &frame->uc.uc_flags);
 272         err |= __put_user(0, &frame->uc.uc_link);
 273         err |= __put_user(me->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
 274         err |= __put_user(sas_ss_flags(regs->rsp),
 275                           &frame->uc.uc_stack.ss_flags);
 276         err |= __put_user(me->sas_ss_size, &frame->uc.uc_stack.ss_size);
 277         err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, set->sig[0], me);
 278         err |= __put_user(fp, &frame->uc.uc_mcontext.fpstate);
 279         if (sizeof(*set) == 16) {
 280                 __put_user(set->sig[0], &frame->uc.uc_sigmask.sig[0]);
 281                 __put_user(set->sig[1], &frame->uc.uc_sigmask.sig[1]);
 282         } else
 283                 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 284
 285         /* Set up to return from userspace.  If provided, use a stub
 286            already in userspace.  */
 287         /* x86-64 should always use SA_RESTORER. */
 288         if (ka->sa.sa_flags & SA_RESTORER) {
 289                 err |= __put_user(ka->sa.sa_restorer, &frame->pretcode);
 290         } else {
 291                 /* could use a vstub here */
 292                 goto give_sigsegv;
 293         }
 294
 295         if (err)
 296                 goto give_sigsegv;
 297
 298 #ifdef DEBUG_SIG
 299         printk("%d old rip %lx old rsp %lx old rax %lx\n", current->pid,regs->rip,regs->rsp,regs->rax);
 300 #endif
 301
 302         /* Set up registers for signal handler */
 303         {
 304                 struct exec_domain *ed = current_thread_info()->exec_domain;
 305                 if (unlikely(ed && ed->signal_invmap && sig < 32))
 306                         sig = ed->signal_invmap[sig];
 307         }
 308         regs->rdi = sig;
 309         /* In case the signal handler was declared without prototypes */
 310         regs->rax = 0;
 311
 312         /* This also works for non SA_SIGINFO handlers because they expect the
 313            next argument after the signal number on the stack. */
 314         regs->rsi = (unsigned long)&frame->info;
 315         regs->rdx = (unsigned long)&frame->uc;
 316         regs->rip = (unsigned long) ka->sa.sa_handler;
 317
 318         regs->rsp = (unsigned long)frame;
 319
 320         set_fs(USER_DS);
 321         regs->eflags &= ~TF_MASK;
 322         if (test_thread_flag(TIF_SINGLESTEP))
 323                 ptrace_notify(SIGTRAP);
 324 #ifdef DEBUG_SIG
 325         printk("SIG deliver (%s:%d): sp=%p pc=%p ra=%p\n",
 326                 current->comm, current->pid, frame, regs->rip, frame->pretcode);
 327 #endif
 328
 329         return;
 330
 331 give_sigsegv:
 332         force_sigsegv(sig, current);
 333 }
 334
 335 /*
 336  * OK, we're invoking a handler
 337  */
 338
 339 static void
 340 handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka,
 341                 sigset_t *oldset, struct pt_regs *regs)
 342 {
 343 #ifdef DEBUG_SIG
 344         printk("handle_signal pid:%d sig:%lu rip:%lx rsp:%lx regs=%p\n",
 345                 current->pid, sig,
 346                 regs->rip, regs->rsp, regs);
 347 #endif
 348
 349         /* Are we from a system call? */
 350         if ((long)regs->orig_rax >= 0) {
 351                 /* If so, check system call restarting.. */
 352                 switch (regs->rax) {
 353                         case -ERESTART_RESTARTBLOCK:
 354                         case -ERESTARTNOHAND:
 355                                 regs->rax = -EINTR;
 356                                 break;
 357
 358                         case -ERESTARTSYS:
 359                                 if (!(ka->sa.sa_flags & SA_RESTART)) {
 360                                         regs->rax = -EINTR;
 361                                         break;
 362                                 }
 363                                 /* fallthrough */
 364                         case -ERESTARTNOINTR:
 365                                 regs->rax = regs->orig_rax;
 366                                 regs->rip -= 2;
 367                                 break;
 368                 }
 369         }
 370
 371         /*
 372          * If TF is set due to a debugger (PT_DTRACE), clear the TF
 373          * flag so that register information in the sigcontext is
 374          * correct.
 375          */
 376         if (unlikely(regs->eflags & TF_MASK)) {
 377                 if (likely(current->ptrace & PT_DTRACE)) {
 378                         current->ptrace &= ~PT_DTRACE;
 379                         regs->eflags &= ~TF_MASK;
 380                 }
 381         }
 382
 383 #ifdef CONFIG_IA32_EMULATION
 384         if (test_thread_flag(TIF_IA32)) {
 385                 if (ka->sa.sa_flags & SA_SIGINFO)
 386                         ia32_setup_rt_frame(sig, ka, info, oldset, regs);
 387                 else
 388                         ia32_setup_frame(sig, ka, oldset, regs);
 389         } else
 390 #endif
 391         setup_rt_frame(sig, ka, info, oldset, regs);
 392
 393         if (!(ka->sa.sa_flags & SA_NODEFER)) {
 394                 spin_lock_irq(&current->sighand->siglock);
 395                 sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
 396                 sigaddset(&current->blocked,sig);
 397                 recalc_sigpending();
 398                 spin_unlock_irq(&current->sighand->siglock);
 399         }
 400 }
 401
 402 /*
 403  * Note that 'init' is a special process: it doesn't get signals it doesn't
 404  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 405  * mistake.
 406  */
 407 int do_signal(struct pt_regs *regs, sigset_t *oldset)
 408 {
 409         struct k_sigaction ka;
 410         siginfo_t info;
 411         int signr;
 412
 413         /*
 414          * We want the common case to go fast, which
 415          * is why we may in certain cases get here from
 416          * kernel mode. Just return without doing anything
 417          * if so.
 418          */
 419         if ((regs->cs & 3) != 3)
 420                 return 1;
 421
 422         if (try_to_freeze(0))
 423                 goto no_signal;
 424
 425         if (!oldset)
 426                 oldset = &current->blocked;
 427
 428         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 429         if (signr > 0) {
 430                 /* Reenable any watchpoints before delivering the
 431                  * signal to user space. The processor register will
 432                  * have been cleared if the watchpoint triggered
 433                  * inside the kernel.
 434                  */
 435                 if (current->thread.debugreg7)
 436                         asm volatile("movq %0,%%db7"    : : "r" (current->thread.debugreg7));
 437
 438                 /* Whee!  Actually deliver the signal.  */
 439                 handle_signal(signr, &info, &ka, oldset, regs);
 440                 return 1;
 441         }
 442
 443  no_signal:
 444         /* Did we come from a system call? */
 445         if ((long)regs->orig_rax >= 0) {
 446                 /* Restart the system call - no handlers present */
 447                 long res = regs->rax;
 448                 if (res == -ERESTARTNOHAND ||
 449                     res == -ERESTARTSYS ||
 450                     res == -ERESTARTNOINTR) {
 451                         regs->rax = regs->orig_rax;
 452                         regs->rip -= 2;
 453                 }
 454                 if (regs->rax == (unsigned long)-ERESTART_RESTARTBLOCK) {
 455                         regs->rax = __NR_restart_syscall;
 456                         regs->rip -= 2;
 457                 }
 458         }
 459         return 0;
 460 }
 461
 462 void do_notify_resume(struct pt_regs *regs, sigset_t *oldset, __u32 thread_info_flags)
 463 {
 464 #ifdef DEBUG_SIG
 465         printk("do_notify_resume flags:%x rip:%lx rsp:%lx caller:%lx pending:%lx\n",
 466                thread_info_flags, regs->rip, regs->rsp, __builtin_return_address(0),signal_pending(current));
 467 #endif
 468
 469         /* Pending single-step? */
 470         if (thread_info_flags & _TIF_SINGLESTEP) {
 471                 regs->eflags |= TF_MASK;
 472                 clear_thread_flag(TIF_SINGLESTEP);
 473         }
 474
 475         /* deal with pending signal delivery */
 476         if (thread_info_flags & _TIF_SIGPENDING)
 477                 do_signal(regs,oldset);
 478 }
 479
 480 void signal_fault(struct pt_regs *regs, void __user *frame, char *where)
 481 {
 482         struct task_struct *me = current;
 483         if (exception_trace)
 484                 printk("%s[%d] bad frame in %s frame:%p rip:%lx rsp:%lx orax:%lx\n",
 485                me->comm,me->pid,where,frame,regs->rip,regs->rsp,regs->orig_rax);
 486
 487         force_sig(SIGSEGV, me);
 488 }