signal.c

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/* MN10300 Signal handling
 *
 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells ([email protected])
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public Licence
 * as published by the Free Software Foundation; either version
 * 2 of the Licence, or (at your option) any later version.
 */

#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/kernel.h>
#include <linux/signal.h>
#include <linux/errno.h>
#include <linux/wait.h>
#include <linux/ptrace.h>
#include <linux/unistd.h>
#include <linux/stddef.h>
#include <linux/tty.h>
#include <linux/personality.h>
#include <linux/suspend.h>
#include <linux/tracehook.h>
#include <asm/cacheflush.h>
#include <asm/ucontext.h>
#include <asm/uaccess.h>
#include <asm/fpu.h>
#include "sigframe.h"

#define DEBUG_SIG 0

/*
 * atomically swap in the new signal mask, and wait for a signal.
 */
asmlinkage long sys_sigsuspend(int history0, int history1, old_sigset_t mask)
{
    sigset_t blocked;
    siginitset(&blocked, mask);
    return sigsuspend(&blocked);
}

/*
 * set signal action syscall
 */
asmlinkage long sys_sigaction(int sig,
                  const struct old_sigaction __user *act,
                  struct old_sigaction __user *oact)
{
    struct k_sigaction new_ka, old_ka;
    int ret;

    if (act) {
        old_sigset_t mask;
        if (verify_area(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 (verify_area(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;
}

/*
 * set alternate signal stack syscall
 */
asmlinkage long sys_sigaltstack(const stack_t __user *uss, stack_t *uoss)
{
    return do_sigaltstack(uss, uoss, current_frame()->sp);
}

/*
 * do a signal return; undo the signal stack.
 */
static int restore_sigcontext(struct pt_regs *regs,
                  struct sigcontext __user *sc, long *_d0)
{
    unsigned int err = 0;

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

    if (is_using_fpu(current))
        fpu_kill_state(current);

#define COPY(x) err |= __get_user(regs->x, &sc->x)
    COPY(d1); COPY(d2); COPY(d3);
    COPY(a0); COPY(a1); COPY(a2); COPY(a3);
    COPY(e0); COPY(e1); COPY(e2); COPY(e3);
    COPY(e4); COPY(e5); COPY(e6); COPY(e7);
    COPY(lar); COPY(lir);
    COPY(mdr); COPY(mdrq);
    COPY(mcvf); COPY(mcrl); COPY(mcrh);
    COPY(sp); COPY(pc);
#undef COPY

    {
        unsigned int tmpflags;
#ifndef CONFIG_MN10300_USING_JTAG
#define USER_EPSW (EPSW_FLAG_Z | EPSW_FLAG_N | EPSW_FLAG_C | EPSW_FLAG_V | \
           EPSW_T | EPSW_nAR)
#else
#define USER_EPSW (EPSW_FLAG_Z | EPSW_FLAG_N | EPSW_FLAG_C | EPSW_FLAG_V | \
           EPSW_nAR)
#endif
        err |= __get_user(tmpflags, &sc->epsw);
        regs->epsw = (regs->epsw & ~USER_EPSW) |
          (tmpflags & USER_EPSW);
        regs->orig_d0 = -1;     /* disable syscall checks */
    }

    {
        struct fpucontext *buf;
        err |= __get_user(buf, &sc->fpucontext);
        if (buf) {
            if (verify_area(VERIFY_READ, buf, sizeof(*buf)))
                goto badframe;
            err |= fpu_restore_sigcontext(buf);
        }
    }

    err |= __get_user(*_d0, &sc->d0);
    return err;

badframe:
    return 1;
}

/*
 * standard signal return syscall
 */
asmlinkage long sys_sigreturn(void)
{
    struct sigframe __user *frame;
    sigset_t set;
    long d0;

    frame = (struct sigframe __user *) current_frame()->sp;
    if (verify_area(VERIFY_READ, frame, sizeof(*frame)))
        goto badframe;
    if (__get_user(set.sig[0], &frame->sc.oldmask))
        goto badframe;

    if (_NSIG_WORDS > 1 &&
        __copy_from_user(&set.sig[1], &frame->extramask,
                 sizeof(frame->extramask)))
        goto badframe;

    set_current_blocked(&set);

    if (restore_sigcontext(current_frame(), &frame->sc, &d0))
        goto badframe;

    return d0;

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

/*
 * realtime signal return syscall
 */
asmlinkage long sys_rt_sigreturn(void)
{
    struct rt_sigframe __user *frame;
    sigset_t set;
    long d0;

    frame = (struct rt_sigframe __user *) current_frame()->sp;
    if (verify_area(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(current_frame(), &frame->uc.uc_mcontext, &d0))
        goto badframe;

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

    return d0;

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

/*
 * store the userspace context into a signal frame
 */
static int setup_sigcontext(struct sigcontext __user *sc,
                struct fpucontext *fpuctx,
                struct pt_regs *regs,
                unsigned long mask)
{
    int tmp, err = 0;

#define COPY(x) err |= __put_user(regs->x, &sc->x)
    COPY(d0); COPY(d1); COPY(d2); COPY(d3);
    COPY(a0); COPY(a1); COPY(a2); COPY(a3);
    COPY(e0); COPY(e1); COPY(e2); COPY(e3);
    COPY(e4); COPY(e5); COPY(e6); COPY(e7);
    COPY(lar); COPY(lir);
    COPY(mdr); COPY(mdrq);
    COPY(mcvf); COPY(mcrl); COPY(mcrh);
    COPY(sp); COPY(epsw); COPY(pc);
#undef COPY

    tmp = fpu_setup_sigcontext(fpuctx);
    if (tmp < 0)
        err = 1;
    else
        err |= __put_user(tmp ? fpuctx : NULL, &sc->fpucontext);

    /* non-iBCS2 extensions.. */
    err |= __put_user(mask, &sc->oldmask);

    return err;
}

/*
 * determine which stack to use..
 */
static inline void __user *get_sigframe(struct k_sigaction *ka,
                    struct pt_regs *regs,
                    size_t frame_size)
{
    unsigned long sp;

    /* default to using normal stack */
    sp = regs->sp;

    /* this is the X/Open sanctioned signal stack switching.  */
    if (ka->sa.sa_flags & SA_ONSTACK) {
        if (sas_ss_flags(sp) == 0)
            sp = current->sas_ss_sp + current->sas_ss_size;
    }

    return (void __user *) ((sp - frame_size) & ~7UL);
}

/*
 * set up a normal signal frame
 */
static int setup_frame(int sig, struct k_sigaction *ka, sigset_t *set,
               struct pt_regs *regs)
{
    struct sigframe __user *frame;
    int rsig;

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

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

    rsig = sig;
    if (sig < 32 &&
        current_thread_info()->exec_domain &&
        current_thread_info()->exec_domain->signal_invmap)
        rsig = current_thread_info()->exec_domain->signal_invmap[sig];

    if (__put_user(rsig, &frame->sig) < 0 ||
        __put_user(&frame->sc, &frame->psc) < 0)
        goto give_sigsegv;

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

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

    /* set up to return from userspace.  If provided, use a stub already in
     * userspace */
    if (ka->sa.sa_flags & SA_RESTORER) {
        if (__put_user(ka->sa.sa_restorer, &frame->pretcode))
            goto give_sigsegv;
    } else {
        if (__put_user((void (*)(void))frame->retcode,
                   &frame->pretcode))
            goto give_sigsegv;
        /* this is mov $,d0; syscall 0 */
        if (__put_user(0x2c, (char *)(frame->retcode + 0)) ||
            __put_user(__NR_sigreturn, (char *)(frame->retcode + 1)) ||
            __put_user(0x00, (char *)(frame->retcode + 2)) ||
            __put_user(0xf0, (char *)(frame->retcode + 3)) ||
            __put_user(0xe0, (char *)(frame->retcode + 4)))
            goto give_sigsegv;
        flush_icache_range((unsigned long) frame->retcode,
                   (unsigned long) frame->retcode + 5);
    }

    /* set up registers for signal handler */
    regs->sp = (unsigned long) frame;
    regs->pc = (unsigned long) ka->sa.sa_handler;
    regs->d0 = sig;
    regs->d1 = (unsigned long) &frame->sc;

#if DEBUG_SIG
    printk(KERN_DEBUG "SIG deliver %d (%s:%d): sp=%p pc=%lx ra=%p\n",
           sig, current->comm, current->pid, frame, regs->pc,
           frame->pretcode);
#endif

    return 0;

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

/*
 * set up a realtime signal frame
 */
static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
              sigset_t *set, struct pt_regs *regs)
{
    struct rt_sigframe __user *frame;
    int rsig;

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

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

    rsig = sig;
    if (sig < 32 &&
        current_thread_info()->exec_domain &&
        current_thread_info()->exec_domain->signal_invmap)
        rsig = current_thread_info()->exec_domain->signal_invmap[sig];

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

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

    /* set up to return from userspace.  If provided, use a stub already in
     * userspace */
    if (ka->sa.sa_flags & SA_RESTORER) {
        if (__put_user(ka->sa.sa_restorer, &frame->pretcode))
            goto give_sigsegv;
    } else {
        if (__put_user((void(*)(void))frame->retcode,
                   &frame->pretcode) ||
            /* This is mov $,d0; syscall 0 */
            __put_user(0x2c, (char *)(frame->retcode + 0)) ||
            __put_user(__NR_rt_sigreturn,
                   (char *)(frame->retcode + 1)) ||
            __put_user(0x00, (char *)(frame->retcode + 2)) ||
            __put_user(0xf0, (char *)(frame->retcode + 3)) ||
            __put_user(0xe0, (char *)(frame->retcode + 4)))
            goto give_sigsegv;

        flush_icache_range((u_long) frame->retcode,
                   (u_long) frame->retcode + 5);
    }

    /* Set up registers for signal handler */
    regs->sp = (unsigned long) frame;
    regs->pc = (unsigned long) ka->sa.sa_handler;
    regs->d0 = sig;
    regs->d1 = (long) &frame->info;

#if DEBUG_SIG
    printk(KERN_DEBUG "SIG deliver %d (%s:%d): sp=%p pc=%lx ra=%p\n",
           sig, current->comm, current->pid, frame, regs->pc,
           frame->pretcode);
#endif

    return 0;

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

static inline void stepback(struct pt_regs *regs)
{
    regs->pc -= 2;
    regs->orig_d0 = -1;
}

/*
 * handle the actual delivery of a signal to userspace
 */
static int handle_signal(int 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_d0 >= 0) {
        /* If so, check system call restarting.. */
        switch (regs->d0) {
        case -ERESTART_RESTARTBLOCK:
        case -ERESTARTNOHAND:
            regs->d0 = -EINTR;
            break;

        case -ERESTARTSYS:
            if (!(ka->sa.sa_flags & SA_RESTART)) {
                regs->d0 = -EINTR;
                break;
            }

            /* fallthrough */
        case -ERESTARTNOINTR:
            regs->d0 = regs->orig_d0;
            stepback(regs);
        }
    }

    /* 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)
        return ret;

    signal_delivered(sig, info, ka, regs,
             test_thread_flag(TIF_SINGLESTEP));
    return 0;
}

/*
 * handle a potential signal
 */
static void do_signal(struct pt_regs *regs)
{
    struct k_sigaction ka;
    siginfo_t info;
    int signr;

    signr = get_signal_to_deliver(&info, &ka, regs, NULL);
    if (signr > 0) {
        if (handle_signal(signr, &info, &ka, regs) == 0) {
        }

        return;
    }

    /* did we come from a system call? */
    if (regs->orig_d0 >= 0) {
        /* restart the system call - no handlers present */
        switch (regs->d0) {
        case -ERESTARTNOHAND:
        case -ERESTARTSYS:
        case -ERESTARTNOINTR:
            regs->d0 = regs->orig_d0;
            stepback(regs);
            break;

        case -ERESTART_RESTARTBLOCK:
            regs->d0 = __NR_restart_syscall;
            stepback(regs);
            break;
        }
    }

    /* if there's no signal to deliver, we just put the saved sigmask
     * back */
    restore_saved_sigmask();
}

/*
 * notification of userspace execution resumption
 * - triggered by current->work.notify_resume
 */
asmlinkage void do_notify_resume(struct pt_regs *regs, u32 thread_info_flags)
{
    /* Pending single-step? */
    if (thread_info_flags & _TIF_SINGLESTEP) {
#ifndef CONFIG_MN10300_USING_JTAG
        regs->epsw |= EPSW_T;
        clear_thread_flag(TIF_SINGLESTEP);
#else
        BUG(); /* no h/w single-step if using JTAG unit */
#endif
    }

    /* deal with pending signal delivery */
    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(current_frame());
    }
}