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

   1/*
   2 * Signal handling
   3 *
   4 * Copyright (C) 2008-2009 Michal Simek <monstr@monstr.eu>
   5 * Copyright (C) 2008-2009 PetaLogix
   6 * Copyright (C) 2003,2004 John Williams <jwilliams@itee.uq.edu.au>
   7 * Copyright (C) 2001 NEC Corporation
   8 * Copyright (C) 2001 Miles Bader <miles@gnu.org>
   9 * Copyright (C) 1999,2000 Niibe Yutaka & Kaz Kojima
  10 * Copyright (C) 1991,1992 Linus Torvalds
  11 *
  12 * 1997-11-28 Modified for POSIX.1b signals by Richard Henderson
  13 *
  14 * This file was was derived from the sh version, arch/sh/kernel/signal.c
  15 *
  16 * This file is subject to the terms and conditions of the GNU General
  17 * Public License. See the file COPYING in the main directory of this
  18 * archive for more details.
  19 */
  20
  21#include <linux/sched.h>
  22#include <linux/mm.h>
  23#include <linux/smp.h>
  24#include <linux/kernel.h>
  25#include <linux/signal.h>
  26#include <linux/errno.h>
  27#include <linux/wait.h>
  28#include <linux/ptrace.h>
  29#include <linux/unistd.h>
  30#include <linux/stddef.h>
  31#include <linux/personality.h>
  32#include <linux/percpu.h>
  33#include <linux/linkage.h>
  34#include <asm/entry.h>
  35#include <asm/ucontext.h>
  36#include <linux/uaccess.h>
  37#include <asm/pgtable.h>
  38#include <asm/pgalloc.h>
  39#include <linux/syscalls.h>
  40#include <asm/cacheflush.h>
  41#include <asm/syscalls.h>
  42
  43#define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
  44
  45asmlinkage int do_signal(struct pt_regs *regs, sigset_t *oldset, int in_sycall);
  46
  47
  48asmlinkage long
  49sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss,
  50                struct pt_regs *regs)
  51{
  52        return do_sigaltstack(uss, uoss, regs->r1);
  53}
  54
  55/*
  56 * Do a signal return; undo the signal stack.
  57 */
  58struct sigframe {
  59        struct sigcontext sc;
  60        unsigned long extramask[_NSIG_WORDS-1];
  61        unsigned long tramp[2]; /* signal trampoline */
  62};
  63
  64struct rt_sigframe {
  65        struct siginfo info;
  66        struct ucontext uc;
  67        unsigned long tramp[2]; /* signal trampoline */
  68};
  69
  70static int restore_sigcontext(struct pt_regs *regs,
  71                                struct sigcontext __user *sc, int *rval_p)
  72{
  73        unsigned int err = 0;
  74
  75#define COPY(x)         {err |= __get_user(regs->x, &sc->regs.x); }
  76        COPY(r0);
  77        COPY(r1);
  78        COPY(r2);       COPY(r3);       COPY(r4);       COPY(r5);
  79        COPY(r6);       COPY(r7);       COPY(r8);       COPY(r9);
  80        COPY(r10);      COPY(r11);      COPY(r12);      COPY(r13);
  81        COPY(r14);      COPY(r15);      COPY(r16);      COPY(r17);
  82        COPY(r18);      COPY(r19);      COPY(r20);      COPY(r21);
  83        COPY(r22);      COPY(r23);      COPY(r24);      COPY(r25);
  84        COPY(r26);      COPY(r27);      COPY(r28);      COPY(r29);
  85        COPY(r30);      COPY(r31);
  86        COPY(pc);       COPY(ear);      COPY(esr);      COPY(fsr);
  87#undef COPY
  88
  89        *rval_p = regs->r3;
  90
  91        return err;
  92}
  93
  94asmlinkage long sys_rt_sigreturn(struct pt_regs *regs)
  95{
  96        struct rt_sigframe __user *frame =
  97                (struct rt_sigframe __user *)(regs->r1 + STATE_SAVE_ARG_SPACE);
  98
  99        sigset_t set;
 100        int rval;
 101
 102        if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 103                goto badframe;
 104
 105        if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
 106                goto badframe;
 107
 108        sigdelsetmask(&set, ~_BLOCKABLE);
 109        spin_lock_irq(&current->sighand->siglock);
 110        current->blocked = set;
 111        recalc_sigpending();
 112        spin_unlock_irq(&current->sighand->siglock);
 113
 114        if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &rval))
 115                goto badframe;
 116
 117        /* It is more difficult to avoid calling this function than to
 118         call it and ignore errors. */
 119        if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->r1))
 120                goto badframe;
 121
 122        return rval;
 123
 124badframe:
 125        force_sig(SIGSEGV, current);
 126        return 0;
 127}
 128
 129/*
 130 * Set up a signal frame.
 131 */
 132
 133static int
 134setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs,
 135                unsigned long mask)
 136{
 137        int err = 0;
 138
 139#define COPY(x)         {err |= __put_user(regs->x, &sc->regs.x); }
 140        COPY(r0);
 141        COPY(r1);
 142        COPY(r2);       COPY(r3);       COPY(r4);       COPY(r5);
 143        COPY(r6);       COPY(r7);       COPY(r8);       COPY(r9);
 144        COPY(r10);      COPY(r11);      COPY(r12);      COPY(r13);
 145        COPY(r14);      COPY(r15);      COPY(r16);      COPY(r17);
 146        COPY(r18);      COPY(r19);      COPY(r20);      COPY(r21);
 147        COPY(r22);      COPY(r23);      COPY(r24);      COPY(r25);
 148        COPY(r26);      COPY(r27);      COPY(r28);      COPY(r29);
 149        COPY(r30);      COPY(r31);
 150        COPY(pc);       COPY(ear);      COPY(esr);      COPY(fsr);
 151#undef COPY
 152
 153        err |= __put_user(mask, &sc->oldmask);
 154
 155        return err;
 156}
 157
 158/*
 159 * Determine which stack to use..
 160 */
 161static inline void __user *
 162get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size)
 163{
 164        /* Default to using normal stack */
 165        unsigned long sp = regs->r1;
 166
 167        if ((ka->sa.sa_flags & SA_ONSTACK) != 0 && !on_sig_stack(sp))
 168                sp = current->sas_ss_sp + current->sas_ss_size;
 169
 170        return (void __user *)((sp - frame_size) & -8UL);
 171}
 172
 173static void setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 174                        sigset_t *set, struct pt_regs *regs)
 175{
 176        struct rt_sigframe __user *frame;
 177        int err = 0;
 178        int signal;
 179
 180        frame = get_sigframe(ka, regs, sizeof(*frame));
 181
 182        if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 183                goto give_sigsegv;
 184
 185        signal = current_thread_info()->exec_domain
 186                && current_thread_info()->exec_domain->signal_invmap
 187                && sig < 32
 188                ? current_thread_info()->exec_domain->signal_invmap[sig]
 189                : sig;
 190
 191        if (info)
 192                err |= copy_siginfo_to_user(&frame->info, info);
 193
 194        /* Create the ucontext. */
 195        err |= __put_user(0, &frame->uc.uc_flags);
 196        err |= __put_user(0, &frame->uc.uc_link);
 197        err |= __put_user((void *)current->sas_ss_sp,
 198                        &frame->uc.uc_stack.ss_sp);
 199        err |= __put_user(sas_ss_flags(regs->r1),
 200                        &frame->uc.uc_stack.ss_flags);
 201        err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
 202        err |= setup_sigcontext(&frame->uc.uc_mcontext,
 203                        regs, set->sig[0]);
 204        err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 205
 206        /* Set up to return from userspace. If provided, use a stub
 207         already in userspace. */
 208        /* minus 8 is offset to cater for "rtsd r15,8" */
 209        /* addi r12, r0, __NR_sigreturn */
 210        err |= __put_user(0x31800000 | __NR_rt_sigreturn ,
 211                        frame->tramp + 0);
 212        /* brki r14, 0x8 */
 213        err |= __put_user(0xb9cc0008, frame->tramp + 1);
 214
 215        /* Return from sighandler will jump to the tramp.
 216         Negative 8 offset because return is rtsd r15, 8 */
 217        regs->r15 = ((unsigned long)frame->tramp)-8;
 218
 219        __invalidate_cache_sigtramp((unsigned long)frame->tramp);
 220
 221        if (err)
 222                goto give_sigsegv;
 223
 224        /* Set up registers for signal handler */
 225        regs->r1 = (unsigned long) frame - STATE_SAVE_ARG_SPACE;
 226
 227        /* Signal handler args: */
 228        regs->r5 = signal; /* arg 0: signum */
 229        regs->r6 = (unsigned long) &frame->info; /* arg 1: siginfo */
 230        regs->r7 = (unsigned long) &frame->uc; /* arg2: ucontext */
 231        /* Offset to handle microblaze rtid r14, 0 */
 232        regs->pc = (unsigned long)ka->sa.sa_handler;
 233
 234        set_fs(USER_DS);
 235
 236#ifdef DEBUG_SIG
 237        printk(KERN_INFO "SIG deliver (%s:%d): sp=%p pc=%08lx\n",
 238                current->comm, current->pid, frame, regs->pc);
 239#endif
 240
 241        return;
 242
 243give_sigsegv:
 244        if (sig == SIGSEGV)
 245                ka->sa.sa_handler = SIG_DFL;
 246        force_sig(SIGSEGV, current);
 247}
 248
 249/* Handle restarting system calls */
 250static inline void
 251handle_restart(struct pt_regs *regs, struct k_sigaction *ka, int has_handler)
 252{
 253        switch (regs->r3) {
 254        case -ERESTART_RESTARTBLOCK:
 255        case -ERESTARTNOHAND:
 256                if (!has_handler)
 257                        goto do_restart;
 258                regs->r3 = -EINTR;
 259                break;
 260        case -ERESTARTSYS:
 261                if (has_handler && !(ka->sa.sa_flags & SA_RESTART)) {
 262                        regs->r3 = -EINTR;
 263                        break;
 264        }
 265        /* fallthrough */
 266        case -ERESTARTNOINTR:
 267do_restart:
 268                /* offset of 4 bytes to re-execute trap (brki) instruction */
 269#ifndef CONFIG_MMU
 270                regs->pc -= 4;
 271#else
 272                /* offset of 8 bytes required = 4 for rtbd
 273                   offset, plus 4 for size of
 274                        "brki r14,8"
 275                   instruction. */
 276                regs->pc -= 8;
 277#endif
 278                break;
 279        }
 280}
 281
 282/*
 283 * OK, we're invoking a handler
 284 */
 285
 286static int
 287handle_signal(unsigned long sig, struct k_sigaction *ka,
 288                siginfo_t *info, sigset_t *oldset, struct pt_regs *regs)
 289{
 290        /* Set up the stack frame */
 291        if (ka->sa.sa_flags & SA_SIGINFO)
 292                setup_rt_frame(sig, ka, info, oldset, regs);
 293        else
 294                setup_rt_frame(sig, ka, NULL, oldset, regs);
 295
 296        if (ka->sa.sa_flags & SA_ONESHOT)
 297                ka->sa.sa_handler = SIG_DFL;
 298
 299        if (!(ka->sa.sa_flags & SA_NODEFER)) {
 300                spin_lock_irq(&current->sighand->siglock);
 301                sigorsets(&current->blocked,
 302                                &current->blocked, &ka->sa.sa_mask);
 303                sigaddset(&current->blocked, sig);
 304                recalc_sigpending();
 305                spin_unlock_irq(&current->sighand->siglock);
 306        }
 307        return 1;
 308}
 309
 310/*
 311 * Note that 'init' is a special process: it doesn't get signals it doesn't
 312 * want to handle. Thus you cannot kill init even with a SIGKILL even by
 313 * mistake.
 314 *
 315 * Note that we go through the signals twice: once to check the signals that
 316 * the kernel can handle, and then we build all the user-level signal handling
 317 * stack-frames in one go after that.
 318 */
 319int do_signal(struct pt_regs *regs, sigset_t *oldset, int in_syscall)
 320{
 321        siginfo_t info;
 322        int signr;
 323        struct k_sigaction ka;
 324#ifdef DEBUG_SIG
 325        printk(KERN_INFO "do signal: %p %p %d\n", regs, oldset, in_syscall);
 326        printk(KERN_INFO "do signal2: %lx %lx %ld [%lx]\n", regs->pc, regs->r1,
 327                        regs->r12, current_thread_info()->flags);
 328#endif
 329        /*
 330         * We want the common case to go fast, which
 331         * is why we may in certain cases get here from
 332         * kernel mode. Just return without doing anything
 333         * if so.
 334         */
 335        if (kernel_mode(regs))
 336                return 1;
 337
 338        if (current_thread_info()->status & TS_RESTORE_SIGMASK)
 339                oldset = &current->saved_sigmask;
 340        else
 341                oldset = &current->blocked;
 342
 343        signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 344        if (signr > 0) {
 345                /* Whee! Actually deliver the signal. */
 346                if (in_syscall)
 347                        handle_restart(regs, &ka, 1);
 348                if (handle_signal(signr, &ka, &info, oldset, regs)) {
 349                        /*
 350                         * A signal was successfully delivered; the saved
 351                         * sigmask will have been stored in the signal frame,
 352                         * and will be restored by sigreturn, so we can simply
 353                         * clear the TS_RESTORE_SIGMASK flag.
 354                         */
 355                        current_thread_info()->status &=
 356                            ~TS_RESTORE_SIGMASK;
 357                }
 358                return 1;
 359        }
 360
 361        if (in_syscall)
 362                handle_restart(regs, NULL, 0);
 363
 364        /*
 365         * If there's no signal to deliver, we just put the saved sigmask
 366         * back.
 367         */
 368        if (current_thread_info()->status & TS_RESTORE_SIGMASK) {
 369                current_thread_info()->status &= ~TS_RESTORE_SIGMASK;
 370                sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
 371        }
 372
 373        /* Did we come from a system call? */
 374        return 0;
 375}
 376