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