LXR linux/arch/c6x/kernel/signal.c

   1/*
   2 *  Port on Texas Instruments TMS320C6x architecture
   3 *
   4 *  Copyright (C) 2004, 2006, 2009, 2010, 2011 Texas Instruments Incorporated
   5 *  Author: Aurelien Jacquiot (aurelien.jacquiot@jaluna.com)
   6 *
   7 *  Updated for 2.6.34: Mark Salter <msalter@redhat.com>
   8 *
   9 *  This program is free software; you can redistribute it and/or modify
  10 *  it under the terms of the GNU General Public License version 2 as
  11 *  published by the Free Software Foundation.
  12 */
  13
  14#include <linux/kernel.h>
  15#include <linux/uaccess.h>
  16#include <linux/syscalls.h>
  17#include <linux/tracehook.h>
  18
  19#include <asm/ucontext.h>
  20#include <asm/cacheflush.h>
  21
  22
  23/*
  24 * Do a signal return, undo the signal stack.
  25 */
  26
  27#define RETCODE_SIZE (9 << 2)   /* 9 instructions = 36 bytes */
  28
  29struct rt_sigframe {
  30        struct siginfo __user *pinfo;
  31        void __user *puc;
  32        struct siginfo info;
  33        struct ucontext uc;
  34        unsigned long retcode[RETCODE_SIZE >> 2];
  35};
  36
  37static int restore_sigcontext(struct pt_regs *regs,
  38                              struct sigcontext __user *sc)
  39{
  40        int err = 0;
  41
  42        /* The access_ok check was done by caller, so use __get_user here */
  43#define COPY(x)  (err |= __get_user(regs->x, &sc->sc_##x))
  44
  45        COPY(sp); COPY(a4); COPY(b4); COPY(a6); COPY(b6); COPY(a8); COPY(b8);
  46        COPY(a0); COPY(a1); COPY(a2); COPY(a3); COPY(a5); COPY(a7); COPY(a9);
  47        COPY(b0); COPY(b1); COPY(b2); COPY(b3); COPY(b5); COPY(b7); COPY(b9);
  48
  49        COPY(a16); COPY(a17); COPY(a18); COPY(a19);
  50        COPY(a20); COPY(a21); COPY(a22); COPY(a23);
  51        COPY(a24); COPY(a25); COPY(a26); COPY(a27);
  52        COPY(a28); COPY(a29); COPY(a30); COPY(a31);
  53        COPY(b16); COPY(b17); COPY(b18); COPY(b19);
  54        COPY(b20); COPY(b21); COPY(b22); COPY(b23);
  55        COPY(b24); COPY(b25); COPY(b26); COPY(b27);
  56        COPY(b28); COPY(b29); COPY(b30); COPY(b31);
  57
  58        COPY(csr); COPY(pc);
  59
  60#undef COPY
  61
  62        return err;
  63}
  64
  65asmlinkage int do_rt_sigreturn(struct pt_regs *regs)
  66{
  67        struct rt_sigframe __user *frame;
  68        sigset_t set;
  69
  70        /* Always make any pending restarted system calls return -EINTR */
  71        current_thread_info()->restart_block.fn = do_no_restart_syscall;
  72
  73        /*
  74         * Since we stacked the signal on a dword boundary,
  75         * 'sp' should be dword aligned here.  If it's
  76         * not, then the user is trying to mess with us.
  77         */
  78        if (regs->sp & 7)
  79                goto badframe;
  80
  81        frame = (struct rt_sigframe __user *) ((unsigned long) regs->sp + 8);
  82
  83        if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
  84                goto badframe;
  85        if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
  86                goto badframe;
  87
  88        set_current_blocked(&set);
  89
  90        if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
  91                goto badframe;
  92
  93        return regs->a4;
  94
  95badframe:
  96        force_sig(SIGSEGV, current);
  97        return 0;
  98}
  99
 100static int setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs,
 101                            unsigned long mask)
 102{
 103        int err = 0;
 104
 105        err |= __put_user(mask, &sc->sc_mask);
 106
 107        /* The access_ok check was done by caller, so use __put_user here */
 108#define COPY(x) (err |= __put_user(regs->x, &sc->sc_##x))
 109
 110        COPY(sp); COPY(a4); COPY(b4); COPY(a6); COPY(b6); COPY(a8); COPY(b8);
 111        COPY(a0); COPY(a1); COPY(a2); COPY(a3); COPY(a5); COPY(a7); COPY(a9);
 112        COPY(b0); COPY(b1); COPY(b2); COPY(b3); COPY(b5); COPY(b7); COPY(b9);
 113
 114        COPY(a16); COPY(a17); COPY(a18); COPY(a19);
 115        COPY(a20); COPY(a21); COPY(a22); COPY(a23);
 116        COPY(a24); COPY(a25); COPY(a26); COPY(a27);
 117        COPY(a28); COPY(a29); COPY(a30); COPY(a31);
 118        COPY(b16); COPY(b17); COPY(b18); COPY(b19);
 119        COPY(b20); COPY(b21); COPY(b22); COPY(b23);
 120        COPY(b24); COPY(b25); COPY(b26); COPY(b27);
 121        COPY(b28); COPY(b29); COPY(b30); COPY(b31);
 122
 123        COPY(csr); COPY(pc);
 124
 125#undef COPY
 126
 127        return err;
 128}
 129
 130static inline void __user *get_sigframe(struct k_sigaction *ka,
 131                                        struct pt_regs *regs,
 132                                        unsigned long framesize)
 133{
 134        unsigned long sp = regs->sp;
 135
 136        /*
 137         * This is the X/Open sanctioned signal stack switching.
 138         */
 139        if ((ka->sa.sa_flags & SA_ONSTACK) && sas_ss_flags(sp) == 0)
 140                sp = current->sas_ss_sp + current->sas_ss_size;
 141
 142        /*
 143         * No matter what happens, 'sp' must be dword
 144         * aligned. Otherwise, nasty things will happen
 145         */
 146        return (void __user *)((sp - framesize) & ~7);
 147}
 148
 149static int setup_rt_frame(int signr, struct k_sigaction *ka, siginfo_t *info,
 150                           sigset_t *set, struct pt_regs *regs)
 151{
 152        struct rt_sigframe __user *frame;
 153        unsigned long __user *retcode;
 154        int err = 0;
 155
 156        frame = get_sigframe(ka, regs, sizeof(*frame));
 157
 158        if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 159                goto segv_and_exit;
 160
 161        err |= __put_user(&frame->info, &frame->pinfo);
 162        err |= __put_user(&frame->uc, &frame->puc);
 163        err |= copy_siginfo_to_user(&frame->info, info);
 164
 165        /* Clear all the bits of the ucontext we don't use.  */
 166        err |= __clear_user(&frame->uc, offsetof(struct ucontext, uc_mcontext));
 167
 168        err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, set->sig[0]);
 169        err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 170
 171        /* Set up to return from userspace */
 172        retcode = (unsigned long __user *) &frame->retcode;
 173
 174        /* The access_ok check was done above, so use __put_user here */
 175#define COPY(x) (err |= __put_user(x, retcode++))
 176
 177        COPY(0x0000002AUL | (__NR_rt_sigreturn << 7));
 178                                /* MVK __NR_rt_sigreturn,B0 */
 179        COPY(0x10000000UL);     /* SWE */
 180        COPY(0x00006000UL);     /* NOP 4 */
 181        COPY(0x00006000UL);     /* NOP 4 */
 182        COPY(0x00006000UL);     /* NOP 4 */
 183        COPY(0x00006000UL);     /* NOP 4 */
 184        COPY(0x00006000UL);     /* NOP 4 */
 185        COPY(0x00006000UL);     /* NOP 4 */
 186        COPY(0x00006000UL);     /* NOP 4 */
 187
 188#undef COPY
 189
 190        if (err)
 191                goto segv_and_exit;
 192
 193        flush_icache_range((unsigned long) &frame->retcode,
 194                           (unsigned long) &frame->retcode + RETCODE_SIZE);
 195
 196        retcode = (unsigned long __user *) &frame->retcode;
 197
 198        /* Change user context to branch to signal handler */
 199        regs->sp = (unsigned long) frame - 8;
 200        regs->b3 = (unsigned long) retcode;
 201        regs->pc = (unsigned long) ka->sa.sa_handler;
 202
 203        /* Give the signal number to the handler */
 204        regs->a4 = signr;
 205
 206        /*
 207         * For realtime signals we must also set the second and third
 208         * arguments for the signal handler.
 209         *   -- Peter Maydell <pmaydell@chiark.greenend.org.uk> 2000-12-06
 210         */
 211        regs->b4 = (unsigned long)&frame->info;
 212        regs->a6 = (unsigned long)&frame->uc;
 213
 214        return 0;
 215
 216segv_and_exit:
 217        force_sigsegv(signr, current);
 218        return -EFAULT;
 219}
 220
 221static inline void
 222handle_restart(struct pt_regs *regs, struct k_sigaction *ka, int has_handler)
 223{
 224        switch (regs->a4) {
 225        case -ERESTARTNOHAND:
 226                if (!has_handler)
 227                        goto do_restart;
 228                regs->a4 = -EINTR;
 229                break;
 230
 231        case -ERESTARTSYS:
 232                if (has_handler && !(ka->sa.sa_flags & SA_RESTART)) {
 233                        regs->a4 = -EINTR;
 234                        break;
 235                }
 236        /* fallthrough */
 237        case -ERESTARTNOINTR:
 238do_restart:
 239                regs->a4 = regs->orig_a4;
 240                regs->pc -= 4;
 241                break;
 242        }
 243}
 244
 245/*
 246 * handle the actual delivery of a signal to userspace
 247 */
 248static void handle_signal(int sig,
 249                         siginfo_t *info, struct k_sigaction *ka,
 250                         struct pt_regs *regs, int syscall)
 251{
 252        /* Are we from a system call? */
 253        if (syscall) {
 254                /* If so, check system call restarting.. */
 255                switch (regs->a4) {
 256                case -ERESTART_RESTARTBLOCK:
 257                case -ERESTARTNOHAND:
 258                        regs->a4 = -EINTR;
 259                        break;
 260
 261                case -ERESTARTSYS:
 262                        if (!(ka->sa.sa_flags & SA_RESTART)) {
 263                                regs->a4 = -EINTR;
 264                                break;
 265                        }
 266
 267                        /* fallthrough */
 268                case -ERESTARTNOINTR:
 269                        regs->a4 = regs->orig_a4;
 270                        regs->pc -= 4;
 271                }
 272        }
 273
 274        /* Set up the stack frame */
 275        if (setup_rt_frame(sig, ka, info, sigmask_to_save(), regs) < 0)
 276                return;
 277        signal_delivered(sig, info, ka, regs, 0);
 278}
 279
 280/*
 281 * handle a potential signal
 282 */
 283static void do_signal(struct pt_regs *regs, int syscall)
 284{
 285        struct k_sigaction ka;
 286        siginfo_t info;
 287        int signr;
 288
 289        /* we want the common case to go fast, which is why we may in certain
 290         * cases get here from kernel mode */
 291        if (!user_mode(regs))
 292                return;
 293
 294        signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 295        if (signr > 0) {
 296                handle_signal(signr, &info, &ka, regs, syscall);
 297                return;
 298        }
 299
 300        /* did we come from a system call? */
 301        if (syscall) {
 302                /* restart the system call - no handlers present */
 303                switch (regs->a4) {
 304                case -ERESTARTNOHAND:
 305                case -ERESTARTSYS:
 306                case -ERESTARTNOINTR:
 307                        regs->a4 = regs->orig_a4;
 308                        regs->pc -= 4;
 309                        break;
 310
 311                case -ERESTART_RESTARTBLOCK:
 312                        regs->a4 = regs->orig_a4;
 313                        regs->b0 = __NR_restart_syscall;
 314                        regs->pc -= 4;
 315                        break;
 316                }
 317        }
 318
 319        /* if there's no signal to deliver, we just put the saved sigmask
 320         * back */
 321        restore_saved_sigmask();
 322}
 323
 324/*
 325 * notification of userspace execution resumption
 326 * - triggered by current->work.notify_resume
 327 */
 328asmlinkage void do_notify_resume(struct pt_regs *regs, u32 thread_info_flags,
 329                                 int syscall)
 330{
 331        /* deal with pending signal delivery */
 332        if (thread_info_flags & (1 << TIF_SIGPENDING))
 333                do_signal(regs, syscall);
 334
 335        if (thread_info_flags & (1 << TIF_NOTIFY_RESUME)) {
 336                clear_thread_flag(TIF_NOTIFY_RESUME);
 337                tracehook_notify_resume(regs);
 338        }
 339}
 340