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->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 ksignal *ksig,
 131                                        struct pt_regs *regs,
 132                                        unsigned long framesize)
 133{
 134        unsigned long sp = sigsp(regs->sp, ksig);
 135
 136        /*
 137         * No matter what happens, 'sp' must be dword
 138         * aligned. Otherwise, nasty things will happen
 139         */
 140        return (void __user *)((sp - framesize) & ~7);
 141}
 142
 143static int setup_rt_frame(struct ksignal *ksig, sigset_t *set,
 144                          struct pt_regs *regs)
 145{
 146        struct rt_sigframe __user *frame;
 147        unsigned long __user *retcode;
 148        int err = 0;
 149
 150        frame = get_sigframe(ksig, regs, sizeof(*frame));
 151
 152        if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 153                return -EFAULT;
 154
 155        err |= __put_user(&frame->info, &frame->pinfo);
 156        err |= __put_user(&frame->uc, &frame->puc);
 157        err |= copy_siginfo_to_user(&frame->info, &ksig->info);
 158
 159        /* Clear all the bits of the ucontext we don't use.  */
 160        err |= __clear_user(&frame->uc, offsetof(struct ucontext, uc_mcontext));
 161
 162        err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, set->sig[0]);
 163        err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 164
 165        /* Set up to return from userspace */
 166        retcode = (unsigned long __user *) &frame->retcode;
 167
 168        /* The access_ok check was done above, so use __put_user here */
 169#define COPY(x) (err |= __put_user(x, retcode++))
 170
 171        COPY(0x0000002AUL | (__NR_rt_sigreturn << 7));
 172                                /* MVK __NR_rt_sigreturn,B0 */
 173        COPY(0x10000000UL);     /* SWE */
 174        COPY(0x00006000UL);     /* NOP 4 */
 175        COPY(0x00006000UL);     /* NOP 4 */
 176        COPY(0x00006000UL);     /* NOP 4 */
 177        COPY(0x00006000UL);     /* NOP 4 */
 178        COPY(0x00006000UL);     /* NOP 4 */
 179        COPY(0x00006000UL);     /* NOP 4 */
 180        COPY(0x00006000UL);     /* NOP 4 */
 181
 182#undef COPY
 183
 184        if (err)
 185                return -EFAULT;
 186
 187        flush_icache_range((unsigned long) &frame->retcode,
 188                           (unsigned long) &frame->retcode + RETCODE_SIZE);
 189
 190        retcode = (unsigned long __user *) &frame->retcode;
 191
 192        /* Change user context to branch to signal handler */
 193        regs->sp = (unsigned long) frame - 8;
 194        regs->b3 = (unsigned long) retcode;
 195        regs->pc = (unsigned long) ksig->ka.sa.sa_handler;
 196
 197        /* Give the signal number to the handler */
 198        regs->a4 = ksig->sig;
 199
 200        /*
 201         * For realtime signals we must also set the second and third
 202         * arguments for the signal handler.
 203         *   -- Peter Maydell <pmaydell@chiark.greenend.org.uk> 2000-12-06
 204         */
 205        regs->b4 = (unsigned long)&frame->info;
 206        regs->a6 = (unsigned long)&frame->uc;
 207
 208        return 0;
 209}
 210
 211static inline void
 212handle_restart(struct pt_regs *regs, struct k_sigaction *ka, int has_handler)
 213{
 214        switch (regs->a4) {
 215        case -ERESTARTNOHAND:
 216                if (!has_handler)
 217                        goto do_restart;
 218                regs->a4 = -EINTR;
 219                break;
 220
 221        case -ERESTARTSYS:
 222                if (has_handler && !(ka->sa.sa_flags & SA_RESTART)) {
 223                        regs->a4 = -EINTR;
 224                        break;
 225                }
 226        /* fallthrough */
 227        case -ERESTARTNOINTR:
 228do_restart:
 229                regs->a4 = regs->orig_a4;
 230                regs->pc -= 4;
 231                break;
 232        }
 233}
 234
 235/*
 236 * handle the actual delivery of a signal to userspace
 237 */
 238static void handle_signal(struct ksignal *ksig, struct pt_regs *regs,
 239                          int syscall)
 240{
 241        int ret;
 242
 243        /* Are we from a system call? */
 244        if (syscall) {
 245                /* If so, check system call restarting.. */
 246                switch (regs->a4) {
 247                case -ERESTART_RESTARTBLOCK:
 248                case -ERESTARTNOHAND:
 249                        regs->a4 = -EINTR;
 250                        break;
 251
 252                case -ERESTARTSYS:
 253                        if (!(ksig->ka.sa.sa_flags & SA_RESTART)) {
 254                                regs->a4 = -EINTR;
 255                                break;
 256                        }
 257
 258                        /* fallthrough */
 259                case -ERESTARTNOINTR:
 260                        regs->a4 = regs->orig_a4;
 261                        regs->pc -= 4;
 262                }
 263        }
 264
 265        /* Set up the stack frame */
 266        ret = setup_rt_frame(ksig, sigmask_to_save(), regs);
 267        signal_setup_done(ret, ksig, 0);
 268}
 269
 270/*
 271 * handle a potential signal
 272 */
 273static void do_signal(struct pt_regs *regs, int syscall)
 274{
 275        struct ksignal ksig;
 276
 277        /* we want the common case to go fast, which is why we may in certain
 278         * cases get here from kernel mode */
 279        if (!user_mode(regs))
 280                return;
 281
 282        if (get_signal(&ksig)) {
 283                handle_signal(&ksig, regs, syscall);
 284                return;
 285        }
 286
 287        /* did we come from a system call? */
 288        if (syscall) {
 289                /* restart the system call - no handlers present */
 290                switch (regs->a4) {
 291                case -ERESTARTNOHAND:
 292                case -ERESTARTSYS:
 293                case -ERESTARTNOINTR:
 294                        regs->a4 = regs->orig_a4;
 295                        regs->pc -= 4;
 296                        break;
 297
 298                case -ERESTART_RESTARTBLOCK:
 299                        regs->a4 = regs->orig_a4;
 300                        regs->b0 = __NR_restart_syscall;
 301                        regs->pc -= 4;
 302                        break;
 303                }
 304        }
 305
 306        /* if there's no signal to deliver, we just put the saved sigmask
 307         * back */
 308        restore_saved_sigmask();
 309}
 310
 311/*
 312 * notification of userspace execution resumption
 313 * - triggered by current->work.notify_resume
 314 */
 315asmlinkage void do_notify_resume(struct pt_regs *regs, u32 thread_info_flags,
 316                                 int syscall)
 317{
 318        /* deal with pending signal delivery */
 319        if (thread_info_flags & (1 << TIF_SIGPENDING))
 320                do_signal(regs, syscall);
 321
 322        if (thread_info_flags & (1 << TIF_NOTIFY_RESUME)) {
 323                clear_thread_flag(TIF_NOTIFY_RESUME);
 324                tracehook_notify_resume(regs);
 325        }
 326}
 327