signal.c

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/*
 * arch/score/kernel/signal.c
 *
 * Score Processor version.
 *
 * Copyright (C) 2009 Sunplus Core Technology Co., Ltd.
 *  Chen Liqin <[email protected]>
 *  Lennox Wu <[email protected]>
 *
 * 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.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, see the file COPYING, or write
 * to the Free Software Foundation, Inc.,
 * 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */

#include <linux/errno.h>
#include <linux/signal.h>
#include <linux/ptrace.h>
#include <linux/unistd.h>
#include <linux/uaccess.h>
#include <linux/tracehook.h>

#include <asm/cacheflush.h>
#include <asm/syscalls.h>
#include <asm/ucontext.h>

struct rt_sigframe {
    u32 rs_ass[4];      /* argument save space */
    u32 rs_code[2];     /* signal trampoline */
    struct siginfo rs_info;
    struct ucontext rs_uc;
};

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

    reg = regs->cp0_epc; err |= __put_user(reg, &sc->sc_pc);
    err |= __put_user(regs->cp0_psr, &sc->sc_psr);
    err |= __put_user(regs->cp0_condition, &sc->sc_condition);


#define save_gp_reg(i) {                \
    reg = regs->regs[i];                \
    err |= __put_user(reg, &sc->sc_regs[i]);    \
} while (0)
    save_gp_reg(0); save_gp_reg(1); save_gp_reg(2);
    save_gp_reg(3); save_gp_reg(4); save_gp_reg(5);
    save_gp_reg(6); save_gp_reg(7); save_gp_reg(8);
    save_gp_reg(9); save_gp_reg(10); save_gp_reg(11);
    save_gp_reg(12); save_gp_reg(13); save_gp_reg(14);
    save_gp_reg(15); save_gp_reg(16); save_gp_reg(17);
    save_gp_reg(18); save_gp_reg(19); save_gp_reg(20);
    save_gp_reg(21); save_gp_reg(22); save_gp_reg(23);
    save_gp_reg(24); save_gp_reg(25); save_gp_reg(26);
    save_gp_reg(27); save_gp_reg(28); save_gp_reg(29);
#undef save_gp_reg

    reg = regs->ceh; err |= __put_user(reg, &sc->sc_mdceh);
    reg = regs->cel; err |= __put_user(reg, &sc->sc_mdcel);
    err |= __put_user(regs->cp0_ecr, &sc->sc_ecr);
    err |= __put_user(regs->cp0_ema, &sc->sc_ema);

    return err;
}

static int restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
{
    int err = 0;
    u32 reg;

    err |= __get_user(regs->cp0_epc, &sc->sc_pc);
    err |= __get_user(regs->cp0_condition, &sc->sc_condition);

    err |= __get_user(reg, &sc->sc_mdceh);
    regs->ceh = (int) reg;
    err |= __get_user(reg, &sc->sc_mdcel);
    regs->cel = (int) reg;

    err |= __get_user(reg, &sc->sc_psr);
    regs->cp0_psr = (int) reg;
    err |= __get_user(reg, &sc->sc_ecr);
    regs->cp0_ecr = (int) reg;
    err |= __get_user(reg, &sc->sc_ema);
    regs->cp0_ema = (int) reg;

#define restore_gp_reg(i) do {              \
    err |= __get_user(reg, &sc->sc_regs[i]);    \
    regs->regs[i] = reg;                \
} while (0)
    restore_gp_reg(0); restore_gp_reg(1); restore_gp_reg(2);
    restore_gp_reg(3); restore_gp_reg(4); restore_gp_reg(5);
    restore_gp_reg(6); restore_gp_reg(7); restore_gp_reg(8);
    restore_gp_reg(9); restore_gp_reg(10); restore_gp_reg(11);
    restore_gp_reg(12); restore_gp_reg(13); restore_gp_reg(14);
    restore_gp_reg(15); restore_gp_reg(16); restore_gp_reg(17);
    restore_gp_reg(18); restore_gp_reg(19); restore_gp_reg(20);
    restore_gp_reg(21); restore_gp_reg(22); restore_gp_reg(23);
    restore_gp_reg(24); restore_gp_reg(25); restore_gp_reg(26);
    restore_gp_reg(27); restore_gp_reg(28); restore_gp_reg(29);
#undef restore_gp_reg

    return err;
}

/*
 * Determine which stack to use..
 */
static 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->regs[0];
    sp -= 32;

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

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

asmlinkage long
score_sigaltstack(struct pt_regs *regs)
{
    const stack_t __user *uss = (const stack_t __user *) regs->regs[4];
    stack_t __user *uoss = (stack_t __user *) regs->regs[5];
    unsigned long usp = regs->regs[0];

    return do_sigaltstack(uss, uoss, usp);
}

asmlinkage long
score_rt_sigreturn(struct pt_regs *regs)
{
    struct rt_sigframe __user *frame;
    sigset_t set;
    int sig;

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

    frame = (struct rt_sigframe __user *) regs->regs[0];
    if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
        goto badframe;
    if (__copy_from_user(&set, &frame->rs_uc.uc_sigmask, sizeof(set)))
        goto badframe;

    set_current_blocked(&set);

    sig = restore_sigcontext(regs, &frame->rs_uc.uc_mcontext);
    if (sig < 0)
        goto badframe;
    else if (sig)
        force_sig(sig, current);

    /* It is more difficult to avoid calling this function than to
       call it and ignore errors.  */
    if (do_sigaltstack(&frame->rs_uc.uc_stack, NULL, regs->regs[0]) == -EFAULT)
        goto badframe;
    regs->is_syscall = 0;

    __asm__ __volatile__(
        "mv\tr0, %0\n\t"
        "la\tr8, syscall_exit\n\t"
        "br\tr8\n\t"
        : : "r" (regs) : "r8");

badframe:
    force_sig(SIGSEGV, current);

    return 0;
}

static int setup_rt_frame(struct k_sigaction *ka, struct pt_regs *regs,
        int signr, sigset_t *set, siginfo_t *info)
{
    struct rt_sigframe __user *frame;
    int err = 0;

    frame = get_sigframe(ka, regs, sizeof(*frame));
    if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
        goto give_sigsegv;

    /*
     * Set up the return code ...
     *
     *         li      v0, __NR_rt_sigreturn
     *         syscall
     */
    err |= __put_user(0x87788000 + __NR_rt_sigreturn*2,
            frame->rs_code + 0);
    err |= __put_user(0x80008002, frame->rs_code + 1);
    flush_cache_sigtramp((unsigned long) frame->rs_code);

    err |= copy_siginfo_to_user(&frame->rs_info, info);
    err |= __put_user(0, &frame->rs_uc.uc_flags);
    err |= __put_user(NULL, &frame->rs_uc.uc_link);
    err |= __put_user((void __user *)current->sas_ss_sp,
                &frame->rs_uc.uc_stack.ss_sp);
    err |= __put_user(sas_ss_flags(regs->regs[0]),
                &frame->rs_uc.uc_stack.ss_flags);
    err |= __put_user(current->sas_ss_size,
                &frame->rs_uc.uc_stack.ss_size);
    err |= setup_sigcontext(regs, &frame->rs_uc.uc_mcontext);
    err |= __copy_to_user(&frame->rs_uc.uc_sigmask, set, sizeof(*set));

    if (err)
        goto give_sigsegv;

    regs->regs[0] = (unsigned long) frame;
    regs->regs[3] = (unsigned long) frame->rs_code;
    regs->regs[4] = signr;
    regs->regs[5] = (unsigned long) &frame->rs_info;
    regs->regs[6] = (unsigned long) &frame->rs_uc;
    regs->regs[29] = (unsigned long) ka->sa.sa_handler;
    regs->cp0_epc = (unsigned long) ka->sa.sa_handler;

    return 0;

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

static void handle_signal(unsigned long sig, siginfo_t *info,
    struct k_sigaction *ka, struct pt_regs *regs)
{
    if (regs->is_syscall) {
        switch (regs->regs[4]) {
        case ERESTART_RESTARTBLOCK:
        case ERESTARTNOHAND:
            regs->regs[4] = EINTR;
            break;
        case ERESTARTSYS:
            if (!(ka->sa.sa_flags & SA_RESTART)) {
                regs->regs[4] = EINTR;
                break;
            }
        case ERESTARTNOINTR:
            regs->regs[4] = regs->orig_r4;
            regs->regs[7] = regs->orig_r7;
            regs->cp0_epc -= 8;
        }

        regs->is_syscall = 0;
    }

    /*
     * Set up the stack frame
     */
    if (setup_rt_frame(ka, regs, sig, sigmask_to_save(), info) < 0)
        return;

    signal_delivered(sig, info, ka, regs, 0);
}

static void do_signal(struct pt_regs *regs)
{
    struct k_sigaction ka;
    siginfo_t info;
    int signr;

    /*
     * 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 (!user_mode(regs))
        return;

    signr = get_signal_to_deliver(&info, &ka, regs, NULL);
    if (signr > 0) {
        /* Actually deliver the signal.  */
        handle_signal(signr, &info, &ka, regs);
        return;
    }

    if (regs->is_syscall) {
        if (regs->regs[4] == ERESTARTNOHAND ||
            regs->regs[4] == ERESTARTSYS ||
            regs->regs[4] == ERESTARTNOINTR) {
            regs->regs[4] = regs->orig_r4;
            regs->regs[7] = regs->orig_r7;
            regs->cp0_epc -= 8;
        }

        if (regs->regs[4] == ERESTART_RESTARTBLOCK) {
            regs->regs[27] = __NR_restart_syscall;
            regs->regs[4] = regs->orig_r4;
            regs->regs[7] = regs->orig_r7;
            regs->cp0_epc -= 8;
        }

        regs->is_syscall = 0;   /* Don't deal with this again.  */
    }

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

/*
 * notification of userspace execution resumption
 * - triggered by the TIF_WORK_MASK flags
 */
asmlinkage void do_notify_resume(struct pt_regs *regs, void *unused,
                __u32 thread_info_flags)
{
    /* 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(regs);
    }
}