/*
 * arch/score/kernel/signal.c
 *
 * Score Processor version.
 *
 * Copyright (C) 2009 Sunplus Core Technology Co., Ltd.
 *  Chen Liqin <liqin.chen@sunplusct.com>
 *  Lennox Wu <lennox.wu@sunplusct.com>
 *
 * 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_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->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);

        if (restore_altstack(&frame->rs_uc.uc_stack))
                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 ksignal *ksig, struct pt_regs *regs,
                          sigset_t *set)
{
        struct rt_sigframe __user *frame;
        int err = 0;

        frame = get_sigframe(&ksig->ka, regs, sizeof(*frame));
        if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
                return -EFAULT;

        /*
         * 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, &ksig->info);
        err |= __put_user(0, &frame->rs_uc.uc_flags);
        err |= __put_user(NULL, &frame->rs_uc.uc_link);
        err |= __save_altstack(&frame->rs_uc.uc_stack, regs->regs[0]);
        err |= setup_sigcontext(regs, &frame->rs_uc.uc_mcontext);
        err |= __copy_to_user(&frame->rs_uc.uc_sigmask, set, sizeof(*set));

        if (err)
                return -EFAULT;

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

        return 0;
}

static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
{
        int ret;

        if (regs->is_syscall) {
                switch (regs->regs[4]) {
                case ERESTART_RESTARTBLOCK:
                case ERESTARTNOHAND:
                        regs->regs[4] = EINTR;
                        break;
                case ERESTARTSYS:
                        if (!(ksig->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
         */
        ret = setup_rt_frame(ksig, regs, sigmask_to_save());

        signal_setup_done(ret, ksig, 0);
}

static void do_signal(struct pt_regs *regs)
{
        struct ksignal ksig;

        /*
         * 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;

        if (get_signal(&ksig)) {
                /* Actually deliver the signal.  */
                handle_signal(&ksig, 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);
        }
}