arch/blackfin/kernel/signal.c

   1 /*
   2  * File:         arch/blackfin/kernel/signal.c
   3  * Based on:
   4  * Author:
   5  *
   6  * Created:
   7  * Description:
   8  *
   9  * Modified:
  10  *               Copyright 2004-2006 Analog Devices Inc.
  11  *
  12  * Bugs:         Enter bugs at http://blackfin.uclinux.org/
  13  *
  14  * This program is free software; you can redistribute it and/or modify
  15  * it under the terms of the GNU General Public License as published by
  16  * the Free Software Foundation; either version 2 of the License, or
  17  * (at your option) any later version.
  18  *
  19  * This program is distributed in the hope that it will be useful,
  20  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  21  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  22  * GNU General Public License for more details.
  23  *
  24  * You should have received a copy of the GNU General Public License
  25  * along with this program; if not, see the file COPYING, or write
  26  * to the Free Software Foundation, Inc.,
  27  * 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  28  */
  29
  30 #include <linux/signal.h>
  31 #include <linux/syscalls.h>
  32 #include <linux/ptrace.h>
  33 #include <linux/tty.h>
  34 #include <linux/personality.h>
  35 #include <linux/binfmts.h>
  36 #include <linux/freezer.h>
  37 #include <linux/uaccess.h>
  38
  39 #include <asm/cacheflush.h>
  40 #include <asm/ucontext.h>
  41 #include <asm/fixed_code.h>
  42
  43 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
  44
  45 /* Location of the trace bit in SYSCFG. */
  46 #define TRACE_BITS 0x0001
  47
  48 struct fdpic_func_descriptor {
  49         unsigned long   text;
  50         unsigned long   GOT;
  51 };
  52
  53 struct rt_sigframe {
  54         int sig;
  55         struct siginfo *pinfo;
  56         void *puc;
  57         /* This is no longer needed by the kernel, but unfortunately userspace
  58          * code expects it to be there.  */
  59         char retcode[8];
  60         struct siginfo info;
  61         struct ucontext uc;
  62 };
  63
  64 asmlinkage int sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss)
  65 {
  66         return do_sigaltstack(uss, uoss, rdusp());
  67 }
  68
  69 static inline int
  70 rt_restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc, int *pr0)
  71 {
  72         unsigned long usp = 0;
  73         int err = 0;
  74
  75 #define RESTORE(x) err |= __get_user(regs->x, &sc->sc_##x)
  76
  77         /* restore passed registers */
  78         RESTORE(r0); RESTORE(r1); RESTORE(r2); RESTORE(r3);
  79         RESTORE(r4); RESTORE(r5); RESTORE(r6); RESTORE(r7);
  80         RESTORE(p0); RESTORE(p1); RESTORE(p2); RESTORE(p3);
  81         RESTORE(p4); RESTORE(p5);
  82         err |= __get_user(usp, &sc->sc_usp);
  83         wrusp(usp);
  84         RESTORE(a0w); RESTORE(a1w);
  85         RESTORE(a0x); RESTORE(a1x);
  86         RESTORE(astat);
  87         RESTORE(rets);
  88         RESTORE(pc);
  89         RESTORE(retx);
  90         RESTORE(fp);
  91         RESTORE(i0); RESTORE(i1); RESTORE(i2); RESTORE(i3);
  92         RESTORE(m0); RESTORE(m1); RESTORE(m2); RESTORE(m3);
  93         RESTORE(l0); RESTORE(l1); RESTORE(l2); RESTORE(l3);
  94         RESTORE(b0); RESTORE(b1); RESTORE(b2); RESTORE(b3);
  95         RESTORE(lc0); RESTORE(lc1);
  96         RESTORE(lt0); RESTORE(lt1);
  97         RESTORE(lb0); RESTORE(lb1);
  98         RESTORE(seqstat);
  99
 100         regs->orig_p0 = -1;     /* disable syscall checks */
 101
 102         *pr0 = regs->r0;
 103         return err;
 104 }
 105
 106 asmlinkage int do_rt_sigreturn(unsigned long __unused)
 107 {
 108         struct pt_regs *regs = (struct pt_regs *)__unused;
 109         unsigned long usp = rdusp();
 110         struct rt_sigframe *frame = (struct rt_sigframe *)(usp);
 111         sigset_t set;
 112         int r0;
 113
 114         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 115                 goto badframe;
 116         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
 117                 goto badframe;
 118
 119         sigdelsetmask(&set, ~_BLOCKABLE);
 120         spin_lock_irq(&current->sighand->siglock);
 121         current->blocked = set;
 122         recalc_sigpending();
 123         spin_unlock_irq(&current->sighand->siglock);
 124
 125         if (rt_restore_sigcontext(regs, &frame->uc.uc_mcontext, &r0))
 126                 goto badframe;
 127
 128         if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->usp) == -EFAULT)
 129                 goto badframe;
 130
 131         return r0;
 132
 133  badframe:
 134         force_sig(SIGSEGV, current);
 135         return 0;
 136 }
 137
 138 static inline int rt_setup_sigcontext(struct sigcontext *sc, struct pt_regs *regs)
 139 {
 140         int err = 0;
 141
 142 #define SETUP(x) err |= __put_user(regs->x, &sc->sc_##x)
 143
 144         SETUP(r0); SETUP(r1); SETUP(r2); SETUP(r3);
 145         SETUP(r4); SETUP(r5); SETUP(r6); SETUP(r7);
 146         SETUP(p0); SETUP(p1); SETUP(p2); SETUP(p3);
 147         SETUP(p4); SETUP(p5);
 148         err |= __put_user(rdusp(), &sc->sc_usp);
 149         SETUP(a0w); SETUP(a1w);
 150         SETUP(a0x); SETUP(a1x);
 151         SETUP(astat);
 152         SETUP(rets);
 153         SETUP(pc);
 154         SETUP(retx);
 155         SETUP(fp);
 156         SETUP(i0); SETUP(i1); SETUP(i2); SETUP(i3);
 157         SETUP(m0); SETUP(m1); SETUP(m2); SETUP(m3);
 158         SETUP(l0); SETUP(l1); SETUP(l2); SETUP(l3);
 159         SETUP(b0); SETUP(b1); SETUP(b2); SETUP(b3);
 160         SETUP(lc0); SETUP(lc1);
 161         SETUP(lt0); SETUP(lt1);
 162         SETUP(lb0); SETUP(lb1);
 163         SETUP(seqstat);
 164
 165         return err;
 166 }
 167
 168 static inline void *get_sigframe(struct k_sigaction *ka, struct pt_regs *regs,
 169                                  size_t frame_size)
 170 {
 171         unsigned long usp;
 172
 173         /* Default to using normal stack.  */
 174         usp = rdusp();
 175
 176         /* This is the X/Open sanctioned signal stack switching.  */
 177         if (ka->sa.sa_flags & SA_ONSTACK) {
 178                 if (!on_sig_stack(usp))
 179                         usp = current->sas_ss_sp + current->sas_ss_size;
 180         }
 181         return (void *)((usp - frame_size) & -8UL);
 182 }
 183
 184 static int
 185 setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t * info,
 186                sigset_t * set, struct pt_regs *regs)
 187 {
 188         struct rt_sigframe *frame;
 189         int err = 0;
 190
 191         frame = get_sigframe(ka, regs, sizeof(*frame));
 192
 193         err |= __put_user((current_thread_info()->exec_domain
 194                            && current_thread_info()->exec_domain->signal_invmap
 195                            && sig < 32
 196                            ? current_thread_info()->exec_domain->
 197                            signal_invmap[sig] : sig), &frame->sig);
 198
 199         err |= __put_user(&frame->info, &frame->pinfo);
 200         err |= __put_user(&frame->uc, &frame->puc);
 201         err |= copy_siginfo_to_user(&frame->info, info);
 202
 203         /* Create the ucontext.  */
 204         err |= __put_user(0, &frame->uc.uc_flags);
 205         err |= __put_user(0, &frame->uc.uc_link);
 206         err |=
 207             __put_user((void *)current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
 208         err |= __put_user(sas_ss_flags(rdusp()), &frame->uc.uc_stack.ss_flags);
 209         err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
 210         err |= rt_setup_sigcontext(&frame->uc.uc_mcontext, regs);
 211         err |= copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 212
 213         if (err)
 214                 goto give_sigsegv;
 215
 216         /* Set up registers for signal handler */
 217         wrusp((unsigned long)frame);
 218         if (current->personality & FDPIC_FUNCPTRS) {
 219                 struct fdpic_func_descriptor __user *funcptr =
 220                         (struct fdpic_func_descriptor *) ka->sa.sa_handler;
 221                 __get_user(regs->pc, &funcptr->text);
 222                 __get_user(regs->p3, &funcptr->GOT);
 223         } else
 224                 regs->pc = (unsigned long)ka->sa.sa_handler;
 225         regs->rets = SIGRETURN_STUB;
 226
 227         regs->r0 = frame->sig;
 228         regs->r1 = (unsigned long)(&frame->info);
 229         regs->r2 = (unsigned long)(&frame->uc);
 230
 231         /*
 232          * Clear the trace flag when entering the signal handler, but
 233          * notify any tracer that was single-stepping it. The tracer
 234          * may want to single-step inside the handler too.
 235          */
 236         if (regs->syscfg & TRACE_BITS) {
 237                 regs->syscfg &= ~TRACE_BITS;
 238                 ptrace_notify(SIGTRAP);
 239         }
 240
 241         return 0;
 242
 243  give_sigsegv:
 244         if (sig == SIGSEGV)
 245                 ka->sa.sa_handler = SIG_DFL;
 246         force_sig(SIGSEGV, current);
 247         return -EFAULT;
 248 }
 249
 250 static inline void
 251 handle_restart(struct pt_regs *regs, struct k_sigaction *ka, int has_handler)
 252 {
 253         switch (regs->r0) {
 254         case -ERESTARTNOHAND:
 255                 if (!has_handler)
 256                         goto do_restart;
 257                 regs->r0 = -EINTR;
 258                 break;
 259
 260         case -ERESTARTSYS:
 261                 if (has_handler && !(ka->sa.sa_flags & SA_RESTART)) {
 262                         regs->r0 = -EINTR;
 263                         break;
 264                 }
 265                 /* fallthrough */
 266         case -ERESTARTNOINTR:
 267  do_restart:
 268                 regs->p0 = regs->orig_p0;
 269                 regs->r0 = regs->orig_r0;
 270                 regs->pc -= 2;
 271                 break;
 272         }
 273 }
 274
 275 /*
 276  * OK, we're invoking a handler
 277  */
 278 static int
 279 handle_signal(int sig, siginfo_t *info, struct k_sigaction *ka,
 280               sigset_t *oldset, struct pt_regs *regs)
 281 {
 282         int ret;
 283
 284         /* are we from a system call? to see pt_regs->orig_p0 */
 285         if (regs->orig_p0 >= 0)
 286                 /* If so, check system call restarting.. */
 287                 handle_restart(regs, ka, 1);
 288
 289         /* set up the stack frame */
 290         ret = setup_rt_frame(sig, ka, info, oldset, regs);
 291
 292         if (ret == 0) {
 293                 spin_lock_irq(&current->sighand->siglock);
 294                 sigorsets(&current->blocked, &current->blocked,
 295                           &ka->sa.sa_mask);
 296                 if (!(ka->sa.sa_flags & SA_NODEFER))
 297                         sigaddset(&current->blocked, sig);
 298                 recalc_sigpending();
 299                 spin_unlock_irq(&current->sighand->siglock);
 300         }
 301         return ret;
 302 }
 303
 304 /*
 305  * Note that 'init' is a special process: it doesn't get signals it doesn't
 306  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 307  * mistake.
 308  *
 309  * Note that we go through the signals twice: once to check the signals
 310  * that the kernel can handle, and then we build all the user-level signal
 311  * handling stack-frames in one go after that.
 312  */
 313 asmlinkage void do_signal(struct pt_regs *regs)
 314 {
 315         siginfo_t info;
 316         int signr;
 317         struct k_sigaction ka;
 318         sigset_t *oldset;
 319
 320         current->thread.esp0 = (unsigned long)regs;
 321
 322         if (try_to_freeze())
 323                 goto no_signal;
 324
 325         if (test_thread_flag(TIF_RESTORE_SIGMASK))
 326                 oldset = &current->saved_sigmask;
 327         else
 328                 oldset = &current->blocked;
 329
 330         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 331         if (signr > 0) {
 332                 /* Whee!  Actually deliver the signal.  */
 333                 if (handle_signal(signr, &info, &ka, oldset, regs) == 0) {
 334                         /* a signal was successfully delivered; the saved
 335                          * sigmask will have been stored in the signal frame,
 336                          * and will be restored by sigreturn, so we can simply
 337                          * clear the TIF_RESTORE_SIGMASK flag */
 338                         if (test_thread_flag(TIF_RESTORE_SIGMASK))
 339                                 clear_thread_flag(TIF_RESTORE_SIGMASK);
 340                 }
 341
 342                 return;
 343         }
 344
 345  no_signal:
 346         /* Did we come from a system call? */
 347         if (regs->orig_p0 >= 0)
 348                 /* Restart the system call - no handlers present */
 349                 handle_restart(regs, NULL, 0);
 350
 351         /* if there's no signal to deliver, we just put the saved sigmask
 352          * back */
 353         if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
 354                 clear_thread_flag(TIF_RESTORE_SIGMASK);
 355                 sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
 356         }
 357 }