signal.c

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/* signal.c: FRV specific bits of signal handling
 *
 * Copyright (C) 2003-5 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells ([email protected])
 * - Derived from arch/m68k/kernel/signal.c
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, 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/personality.h>
#include <linux/tracehook.h>
#include <asm/ucontext.h>
#include <asm/uaccess.h>
#include <asm/cacheflush.h>

#define DEBUG_SIG 0

struct fdpic_func_descriptor {
    unsigned long   text;
    unsigned long   GOT;
};

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

asmlinkage int 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 (!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 __user *uss, stack_t __user *uoss)
{
    return do_sigaltstack(uss, uoss, __frame->sp);
}


/*
 * Do a signal return; undo the signal stack.
 */

struct sigframe
{
    __sigrestore_t pretcode;
    int sig;
    struct sigcontext sc;
    unsigned long extramask[_NSIG_WORDS-1];
    uint32_t retcode[2];
};

struct rt_sigframe
{
    __sigrestore_t pretcode;
    int sig;
    struct siginfo __user *pinfo;
    void __user *puc;
    struct siginfo info;
    struct ucontext uc;
    uint32_t retcode[2];
};

static int restore_sigcontext(struct sigcontext __user *sc, int *_gr8)
{
    struct user_context *user = current->thread.user;
    unsigned long tbr, psr;

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

    tbr = user->i.tbr;
    psr = user->i.psr;
    if (copy_from_user(user, &sc->sc_context, sizeof(sc->sc_context)))
        goto badframe;
    user->i.tbr = tbr;
    user->i.psr = psr;

    restore_user_regs(user);

    user->i.syscallno = -1;     /* disable syscall checks */

    *_gr8 = user->i.gr[8];
    return 0;

 badframe:
    return 1;
}

asmlinkage int sys_sigreturn(void)
{
    struct sigframe __user *frame = (struct sigframe __user *) __frame->sp;
    sigset_t set;
    int gr8;

    if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
        goto badframe;
    if (__get_user(set.sig[0], &frame->sc.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(&frame->sc, &gr8))
        goto badframe;
    return gr8;

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

asmlinkage int sys_rt_sigreturn(void)
{
    struct rt_sigframe __user *frame = (struct rt_sigframe __user *) __frame->sp;
    sigset_t set;
    int gr8;

    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(&frame->uc.uc_mcontext, &gr8))
        goto badframe;

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

    return gr8;

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

/*
 * Set up a signal frame
 */
static int setup_sigcontext(struct sigcontext __user *sc, unsigned long mask)
{
    save_user_regs(current->thread.user);

    if (copy_to_user(&sc->sc_context, current->thread.user, sizeof(sc->sc_context)) != 0)
        goto badframe;

    /* non-iBCS2 extensions.. */
    if (__put_user(mask, &sc->sc_oldmask) < 0)
        goto badframe;

    return 0;

 badframe:
    return 1;
}

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

    /* Default to using normal stack */
    sp = __frame->sp;

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

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

} /* end get_sigframe() */

/*****************************************************************************/
/*
 *
 */
static int setup_frame(int sig, struct k_sigaction *ka, sigset_t *set)
{
    struct sigframe __user *frame;
    int rsig;

    set_fs(USER_DS);

    frame = get_sigframe(ka, 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)
        goto give_sigsegv;

    if (setup_sigcontext(&frame->sc, 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) < 0)
            goto give_sigsegv;
    }
    else {
        /* Set up the following code on the stack:
         *  setlos  #__NR_sigreturn,gr7
         *  tira    gr0,0
         */
        if (__put_user((__sigrestore_t)frame->retcode, &frame->pretcode) ||
            __put_user(0x8efc0000|__NR_sigreturn, &frame->retcode[0]) ||
            __put_user(0xc0700000, &frame->retcode[1]))
            goto give_sigsegv;

        flush_icache_range((unsigned long) frame->retcode,
                   (unsigned long) (frame->retcode + 2));
    }

    /* Set up registers for the signal handler */
    if (current->personality & FDPIC_FUNCPTRS) {
        struct fdpic_func_descriptor __user *funcptr =
            (struct fdpic_func_descriptor __user *) ka->sa.sa_handler;
        struct fdpic_func_descriptor desc;
        if (copy_from_user(&desc, funcptr, sizeof(desc)))
            goto give_sigsegv;
        __frame->pc = desc.text;
        __frame->gr15 = desc.GOT;
    } else {
        __frame->pc   = (unsigned long) ka->sa.sa_handler;
        __frame->gr15 = 0;
    }

    __frame->sp   = (unsigned long) frame;
    __frame->lr   = (unsigned long) &frame->retcode;
    __frame->gr8  = sig;

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

    return 0;

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

} /* end setup_frame() */

/*****************************************************************************/
/*
 *
 */
static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
              sigset_t *set)
{
    struct rt_sigframe __user *frame;
    int rsig;

    set_fs(USER_DS);

    frame = get_sigframe(ka, 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))
        goto give_sigsegv;

    if (copy_siginfo_to_user(&frame->info, info))
        goto give_sigsegv;

    /* Create the ucontext.  */
    if (__put_user(0, &frame->uc.uc_flags) ||
        __put_user(NULL, &frame->uc.uc_link) ||
        __put_user((void __user *)current->sas_ss_sp, &frame->uc.uc_stack.ss_sp) ||
        __put_user(sas_ss_flags(__frame->sp), &frame->uc.uc_stack.ss_flags) ||
        __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size))
        goto give_sigsegv;

    if (setup_sigcontext(&frame->uc.uc_mcontext, set->sig[0]))
        goto give_sigsegv;

    if (__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 {
        /* Set up the following code on the stack:
         *  setlos  #__NR_sigreturn,gr7
         *  tira    gr0,0
         */
        if (__put_user((__sigrestore_t)frame->retcode, &frame->pretcode) ||
            __put_user(0x8efc0000|__NR_rt_sigreturn, &frame->retcode[0]) ||
            __put_user(0xc0700000, &frame->retcode[1]))
            goto give_sigsegv;

        flush_icache_range((unsigned long) frame->retcode,
                   (unsigned long) (frame->retcode + 2));
    }

    /* Set up registers for signal handler */
    if (current->personality & FDPIC_FUNCPTRS) {
        struct fdpic_func_descriptor __user *funcptr =
            (struct fdpic_func_descriptor __user *) ka->sa.sa_handler;
        struct fdpic_func_descriptor desc;
        if (copy_from_user(&desc, funcptr, sizeof(desc)))
            goto give_sigsegv;
        __frame->pc = desc.text;
        __frame->gr15 = desc.GOT;
    } else {
        __frame->pc   = (unsigned long) ka->sa.sa_handler;
        __frame->gr15 = 0;
    }

    __frame->sp  = (unsigned long) frame;
    __frame->lr  = (unsigned long) &frame->retcode;
    __frame->gr8 = sig;
    __frame->gr9 = (unsigned long) &frame->info;

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

    return 0;

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

} /* end setup_rt_frame() */

/*****************************************************************************/
/*
 * OK, we're invoking a handler
 */
static void handle_signal(unsigned long sig, siginfo_t *info,
             struct k_sigaction *ka)
{
    sigset_t *oldset = sigmask_to_save();
    int ret;

    /* Are we from a system call? */
    if (__frame->syscallno != -1) {
        /* If so, check system call restarting.. */
        switch (__frame->gr8) {
        case -ERESTART_RESTARTBLOCK:
        case -ERESTARTNOHAND:
            __frame->gr8 = -EINTR;
            break;

        case -ERESTARTSYS:
            if (!(ka->sa.sa_flags & SA_RESTART)) {
                __frame->gr8 = -EINTR;
                break;
            }

            /* fallthrough */
        case -ERESTARTNOINTR:
            __frame->gr8 = __frame->orig_gr8;
            __frame->pc -= 4;
        }
        __frame->syscallno = -1;
    }

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

    if (ret)
        return;

    signal_delivered(sig, info, ka, __frame,
                 test_thread_flag(TIF_SINGLESTEP));
} /* end handle_signal() */

/*****************************************************************************/
/*
 * 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(void)
{
    struct k_sigaction ka;
    siginfo_t info;
    int signr;

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

    /* Did we come from a system call? */
    if (__frame->syscallno != -1) {
        /* Restart the system call - no handlers present */
        switch (__frame->gr8) {
        case -ERESTARTNOHAND:
        case -ERESTARTSYS:
        case -ERESTARTNOINTR:
            __frame->gr8 = __frame->orig_gr8;
            __frame->pc -= 4;
            break;

        case -ERESTART_RESTARTBLOCK:
            __frame->gr7 = __NR_restart_syscall;
            __frame->pc -= 4;
            break;
        }
        __frame->syscallno = -1;
    }

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

/*****************************************************************************/
/*
 * notification of userspace execution resumption
 * - triggered by the TIF_WORK_MASK flags
 */
asmlinkage void do_notify_resume(__u32 thread_info_flags)
{
    /* pending single-step? */
    if (thread_info_flags & _TIF_SINGLESTEP)
        clear_thread_flag(TIF_SINGLESTEP);

    /* deal with pending signal delivery */
    if (thread_info_flags & _TIF_SIGPENDING)
        do_signal();

    /* deal with notification on about to resume userspace execution */
    if (thread_info_flags & _TIF_NOTIFY_RESUME) {
        clear_thread_flag(TIF_NOTIFY_RESUME);
        tracehook_notify_resume(__frame);
    }

} /* end do_notify_resume() */