LXR linux/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
  48struct fdpic_func_descriptor {
  49        unsigned long   text;
  50        unsigned long   GOT;
  51};
  52
  53struct 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
  64asmlinkage int sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss)
  65{
  66        return do_sigaltstack(uss, uoss, rdusp());
  67}
  68
  69static inline int
  70rt_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
 106asmlinkage 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
 138static 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
 168static 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
 184static int
 185setup_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
 250static inline void
 251handle_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 */
 278static int
 279handle_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 */
 313asmlinkage 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}
 358