signal.c

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/*
 *  linux/arch/h8300/kernel/signal.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file COPYING in the main directory of this archive
 * for more details.
 */

/*
 * uClinux H8/300 support by Yoshinori Sato <[email protected]>
 *                and David McCullough <[email protected]>
 *
 * Based on
 * Linux/m68k by Hamish Macdonald
 */

/*
 * ++roman (07/09/96): implemented signal stacks (specially for tosemu on
 * Atari :-) Current limitation: Only one sigstack can be active at one time.
 * If a second signal with SA_ONSTACK set arrives while working on a sigstack,
 * SA_ONSTACK is ignored. This behaviour avoids lots of trouble with nested
 * signal handlers!
 */

#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/kernel.h>
#include <linux/signal.h>
#include <linux/syscalls.h>
#include <linux/errno.h>
#include <linux/wait.h>
#include <linux/ptrace.h>
#include <linux/unistd.h>
#include <linux/stddef.h>
#include <linux/highuid.h>
#include <linux/personality.h>
#include <linux/tty.h>
#include <linux/binfmts.h>
#include <linux/tracehook.h>

#include <asm/setup.h>
#include <asm/uaccess.h>
#include <asm/pgtable.h>
#include <asm/traps.h>
#include <asm/ucontext.h>

/*
 * Atomically swap in the new signal mask, and wait for a signal.
 */
asmlinkage int
sys_sigsuspend(int unused1, int unused2, old_sigset_t mask)
{
    sigset_t blocked;
    siginitset(&blocked, mask);
    return sigsuspend(&blocked);
}

asmlinkage int 
sys_sigaction(int sig, const struct old_sigaction *act,
          struct old_sigaction *oact)
{
    struct k_sigaction new_ka, old_ka;
    int ret;

    if (act) {
        old_sigset_t mask;
        if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
            __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
            __get_user(new_ka.sa.sa_restorer, &act->sa_restorer) ||
            __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
            __get_user(mask, &act->sa_mask))
            return -EFAULT;
        siginitset(&new_ka.sa.sa_mask, mask);
    }

    ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);

    if (!ret && oact) {
        if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
            __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
            __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer) ||
            __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
            __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
            return -EFAULT;
    }

    return ret;
}

asmlinkage int
sys_sigaltstack(const stack_t *uss, stack_t *uoss)
{
    return do_sigaltstack(uss, uoss, rdusp());
}


/*
 * Do a signal return; undo the signal stack.
 *
 * Keep the return code on the stack quadword aligned!
 * That makes the cache flush below easier.
 */

struct sigframe
{
    long dummy_er0;
    long dummy_vector;
#if defined(CONFIG_CPU_H8S)
    short dummy_exr;
#endif
    long dummy_pc;
    char *pretcode;
    unsigned char retcode[8];
    unsigned long extramask[_NSIG_WORDS-1];
    struct sigcontext sc;
    int sig;
} __attribute__((aligned(2),packed));

struct rt_sigframe
{
    long dummy_er0;
    long dummy_vector;
#if defined(CONFIG_CPU_H8S)
    short dummy_exr;
#endif
    long dummy_pc;
    char *pretcode;
    struct siginfo *pinfo;
    void *puc;
    unsigned char retcode[8];
    struct siginfo info;
    struct ucontext uc;
    int sig;
} __attribute__((aligned(2),packed));

static inline int
restore_sigcontext(struct pt_regs *regs, struct sigcontext *usc,
           int *pd0)
{
    int err = 0;
    unsigned int ccr;
    unsigned int usp;
    unsigned int er0;

    /* Always make any pending restarted system calls return -EINTR */
    current_thread_info()->restart_block.fn = do_no_restart_syscall;

#define COPY(r) err |= __get_user(regs->r, &usc->sc_##r)    /* restore passed registers */
    COPY(er1);
    COPY(er2);
    COPY(er3);
    COPY(er5);
    COPY(pc);
    ccr = regs->ccr & 0x10;
    COPY(ccr);
#undef COPY
    regs->ccr &= 0xef;
    regs->ccr |= ccr;
    regs->orig_er0 = -1;        /* disable syscall checks */
    err |= __get_user(usp, &usc->sc_usp);
    wrusp(usp);

    err |= __get_user(er0, &usc->sc_er0);
    *pd0 = er0;
    return err;
}

asmlinkage int do_sigreturn(unsigned long __unused,...)
{
    struct pt_regs *regs = (struct pt_regs *) (&__unused - 1);
    unsigned long usp = rdusp();
    struct sigframe *frame = (struct sigframe *)(usp - 4);
    sigset_t set;
    int er0;

    if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
        goto badframe;
    if (__get_user(set.sig[0], &frame->sc.sc_mask) ||
        (_NSIG_WORDS > 1 &&
         __copy_from_user(&set.sig[1], &frame->extramask,
                  sizeof(frame->extramask))))
        goto badframe;

    set_current_blocked(&set);
    
    if (restore_sigcontext(regs, &frame->sc, &er0))
        goto badframe;
    return er0;

badframe:
    force_sig(SIGSEGV, current);
    return 0;
}

asmlinkage int do_rt_sigreturn(unsigned long __unused,...)
{
    struct pt_regs *regs = (struct pt_regs *) &__unused;
    unsigned long usp = rdusp();
    struct rt_sigframe *frame = (struct rt_sigframe *)(usp - 4);
    sigset_t set;
    int er0;

    if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
        goto badframe;
    if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
        goto badframe;

    set_current_blocked(&set);
    
    if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &er0))
        goto badframe;

    if (do_sigaltstack(&frame->uc.uc_stack, NULL, usp) == -EFAULT)
        goto badframe;

    return er0;

badframe:
    force_sig(SIGSEGV, current);
    return 0;
}

static int setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs,
                 unsigned long mask)
{
    int err = 0;

    err |= __put_user(regs->er0, &sc->sc_er0);
    err |= __put_user(regs->er1, &sc->sc_er1);
    err |= __put_user(regs->er2, &sc->sc_er2);
    err |= __put_user(regs->er3, &sc->sc_er3);
    err |= __put_user(regs->er4, &sc->sc_er4);
    err |= __put_user(regs->er5, &sc->sc_er5);
    err |= __put_user(regs->er6, &sc->sc_er6);
    err |= __put_user(rdusp(),   &sc->sc_usp);
    err |= __put_user(regs->pc,  &sc->sc_pc);
    err |= __put_user(regs->ccr, &sc->sc_ccr);
    err |= __put_user(mask,      &sc->sc_mask);

    return err;
}

static inline void *
get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size)
{
    unsigned long usp;

    /* Default to using normal stack.  */
    usp = rdusp();

    /* This is the X/Open sanctioned signal stack switching.  */
    if (ka->sa.sa_flags & SA_ONSTACK) {
        if (!sas_ss_flags(usp))
            usp = current->sas_ss_sp + current->sas_ss_size;
    }
    return (void *)((usp - frame_size) & -8UL);
}

static int setup_frame (int sig, struct k_sigaction *ka,
             sigset_t *set, struct pt_regs *regs)
{
    struct sigframe *frame;
    int err = 0;
    int usig;
    unsigned char *ret;

    frame = get_sigframe(ka, regs, sizeof(*frame));

    if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
        goto give_sigsegv;

    usig = current_thread_info()->exec_domain
        && current_thread_info()->exec_domain->signal_invmap
        && sig < 32
        ? current_thread_info()->exec_domain->signal_invmap[sig]
        : sig;

    err |= __put_user(usig, &frame->sig);
    if (err)
        goto give_sigsegv;

    err |= setup_sigcontext(&frame->sc, regs, set->sig[0]);
    if (err)
        goto give_sigsegv;

    if (_NSIG_WORDS > 1) {
        err |= copy_to_user(frame->extramask, &set->sig[1],
                    sizeof(frame->extramask));
        if (err)
            goto give_sigsegv;
    }

    ret = frame->retcode;
    if (ka->sa.sa_flags & SA_RESTORER)
        ret = (unsigned char *)(ka->sa.sa_restorer);
    else {
        /* sub.l er0,er0; mov.b #__NR_sigreturn,r0l; trapa #0 */
        err |= __put_user(0x1a80f800 + (__NR_sigreturn & 0xff),
                  (unsigned long *)(frame->retcode + 0));
        err |= __put_user(0x5700, (unsigned short *)(frame->retcode + 4));
    }

    /* Set up to return from userspace.  */
    err |= __put_user(ret, &frame->pretcode);

    if (err)
        goto give_sigsegv;

    /* Set up registers for signal handler */
    wrusp ((unsigned long) frame);
    regs->pc = (unsigned long) ka->sa.sa_handler;
    regs->er0 = (current_thread_info()->exec_domain
               && current_thread_info()->exec_domain->signal_invmap
               && sig < 32
               ? current_thread_info()->exec_domain->signal_invmap[sig]
                  : sig);
    regs->er1 = (unsigned long)&(frame->sc);
    regs->er5 = current->mm->start_data;    /* GOT base */

    return 0;

give_sigsegv:
    force_sigsegv(sig, current);
    return -EFAULT;
}

static int setup_rt_frame (int sig, struct k_sigaction *ka, siginfo_t *info,
                sigset_t *set, struct pt_regs *regs)
{
    struct rt_sigframe *frame;
    int err = 0;
    int usig;
    unsigned char *ret;

    frame = get_sigframe(ka, regs, sizeof(*frame));

    if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
        goto give_sigsegv;

    usig = current_thread_info()->exec_domain
        && current_thread_info()->exec_domain->signal_invmap
        && sig < 32
        ? current_thread_info()->exec_domain->signal_invmap[sig]
        : sig;

    err |= __put_user(usig, &frame->sig);
    if (err)
        goto give_sigsegv;

    err |= __put_user(&frame->info, &frame->pinfo);
    err |= __put_user(&frame->uc, &frame->puc);
    err |= copy_siginfo_to_user(&frame->info, info);
    if (err)
        goto give_sigsegv;

    /* Create the ucontext.  */
    err |= __put_user(0, &frame->uc.uc_flags);
    err |= __put_user(0, &frame->uc.uc_link);
    err |= __put_user((void *)current->sas_ss_sp,
              &frame->uc.uc_stack.ss_sp);
    err |= __put_user(sas_ss_flags(rdusp()),
              &frame->uc.uc_stack.ss_flags);
    err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
    err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, set->sig[0]);
    err |= copy_to_user (&frame->uc.uc_sigmask, set, sizeof(*set));
    if (err)
        goto give_sigsegv;

    /* Set up to return from userspace.  */
    ret = frame->retcode;
    if (ka->sa.sa_flags & SA_RESTORER)
        ret = (unsigned char *)(ka->sa.sa_restorer);
    else {
        /* sub.l er0,er0; mov.b #__NR_sigreturn,r0l; trapa #0 */
        err |= __put_user(0x1a80f800 + (__NR_sigreturn & 0xff),
                  (unsigned long *)(frame->retcode + 0));
        err |= __put_user(0x5700, (unsigned short *)(frame->retcode + 4));
    }
    err |= __put_user(ret, &frame->pretcode);

    if (err)
        goto give_sigsegv;

    /* Set up registers for signal handler */
    wrusp ((unsigned long) frame);
    regs->pc  = (unsigned long) ka->sa.sa_handler;
    regs->er0 = (current_thread_info()->exec_domain
             && current_thread_info()->exec_domain->signal_invmap
             && sig < 32
             ? current_thread_info()->exec_domain->signal_invmap[sig]
             : sig);
    regs->er1 = (unsigned long)&(frame->info);
    regs->er2 = (unsigned long)&frame->uc;
    regs->er5 = current->mm->start_data;    /* GOT base */

    return 0;

give_sigsegv:
    force_sigsegv(sig, current);
    return -EFAULT;
}

/*
 * OK, we're invoking a handler
 */
static void
handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka,
          struct pt_regs * regs)
{
    sigset_t *oldset = sigmask_to_save();
    int ret;
    /* are we from a system call? */
    if (regs->orig_er0 >= 0) {
        switch (regs->er0) {
                case -ERESTART_RESTARTBLOCK:
            case -ERESTARTNOHAND:
                regs->er0 = -EINTR;
                break;

            case -ERESTARTSYS:
                if (!(ka->sa.sa_flags & SA_RESTART)) {
                    regs->er0 = -EINTR;
                    break;
                }
            /* fallthrough */
            case -ERESTARTNOINTR:
                regs->er0 = regs->orig_er0;
                regs->pc -= 2;
        }
    }

    /* set up the stack frame */
    if (ka->sa.sa_flags & SA_SIGINFO)
        ret = setup_rt_frame(sig, ka, info, oldset, regs);
    else
        ret = setup_frame(sig, ka, oldset, regs);

    if (!ret)
        signal_delivered(sig, info, ka, regs, 0);
}

/*
 * Note that 'init' is a special process: it doesn't get signals it doesn't
 * want to handle. Thus you cannot kill init even with a SIGKILL even by
 * mistake.
 */
static void do_signal(struct pt_regs *regs)
{
    siginfo_t info;
    int signr;
    struct k_sigaction ka;

    /*
     * We want the common case to go fast, which
     * is why we may in certain cases get here from
     * kernel mode. Just return without doing anything
     * if so.
     */
    if ((regs->ccr & 0x10))
        return;

    current->thread.esp0 = (unsigned long) regs;

    signr = get_signal_to_deliver(&info, &ka, regs, NULL);
    if (signr > 0) {
        /* Whee!  Actually deliver the signal.  */
        handle_signal(signr, &info, &ka, regs);
        return;
    }
    /* Did we come from a system call? */
    if (regs->orig_er0 >= 0) {
        /* Restart the system call - no handlers present */
        if (regs->er0 == -ERESTARTNOHAND ||
            regs->er0 == -ERESTARTSYS ||
            regs->er0 == -ERESTARTNOINTR) {
            regs->er0 = regs->orig_er0;
            regs->pc -= 2;
        }
        if (regs->er0 == -ERESTART_RESTARTBLOCK){
            regs->er0 = __NR_restart_syscall;
            regs->pc -= 2;
        }
    }

    /* If there's no signal to deliver, we just restore the saved mask.  */
    restore_saved_sigmask();
}

asmlinkage void do_notify_resume(struct pt_regs *regs, u32 thread_info_flags)
{
    if (thread_info_flags & _TIF_SIGPENDING)
        do_signal(regs);

    if (thread_info_flags & _TIF_NOTIFY_RESUME) {
        clear_thread_flag(TIF_NOTIFY_RESUME);
        tracehook_notify_resume(regs);
    }
}