/*
 * 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.
 *
 * Copyright (C) 1991, 1992  Linus Torvalds
 * Copyright (C) 1994 - 2000, 2006  Ralf Baechle
 * Copyright (C) 1999, 2000 Silicon Graphics, Inc.
 * Copyright (C) 2016, Imagination Technologies Ltd.
 */
#include <linux/compiler.h>
#include <linux/errno.h>
#include <linux/signal.h>
#include <linux/sched/signal.h>
#include <linux/uaccess.h>

#include <asm/abi.h>
#include <asm/compat-signal.h>
#include <asm/dsp.h>
#include <asm/sim.h>
#include <asm/unistd.h>

#include "signal-common.h"

/*
 * Including <asm/unistd.h> would give use the 64-bit syscall numbers ...
 */
#define __NR_O32_restart_syscall        4253

struct sigframe32 {
        u32 sf_ass[4];          /* argument save space for o32 */
        u32 sf_pad[2];          /* Was: signal trampoline */
        struct sigcontext32 sf_sc;
        compat_sigset_t sf_mask;
};

struct ucontext32 {
        u32                 uc_flags;
        s32                 uc_link;
        compat_stack_t      uc_stack;
        struct sigcontext32 uc_mcontext;
        compat_sigset_t     uc_sigmask;   /* mask last for extensibility */
};

struct rt_sigframe32 {
        u32 rs_ass[4];                  /* argument save space for o32 */
        u32 rs_pad[2];                  /* Was: signal trampoline */
        compat_siginfo_t rs_info;
        struct ucontext32 rs_uc;
};

static int setup_sigcontext32(struct pt_regs *regs,
                              struct sigcontext32 __user *sc)
{
        int err = 0;
        int i;

        err |= __put_user(regs->cp0_epc, &sc->sc_pc);

        err |= __put_user(0, &sc->sc_regs[0]);
        for (i = 1; i < 32; i++)
                err |= __put_user(regs->regs[i], &sc->sc_regs[i]);

        err |= __put_user(regs->hi, &sc->sc_mdhi);
        err |= __put_user(regs->lo, &sc->sc_mdlo);
        if (cpu_has_dsp) {
                err |= __put_user(rddsp(DSP_MASK), &sc->sc_dsp);
                err |= __put_user(mfhi1(), &sc->sc_hi1);
                err |= __put_user(mflo1(), &sc->sc_lo1);
                err |= __put_user(mfhi2(), &sc->sc_hi2);
                err |= __put_user(mflo2(), &sc->sc_lo2);
                err |= __put_user(mfhi3(), &sc->sc_hi3);
                err |= __put_user(mflo3(), &sc->sc_lo3);
        }

        /*
         * Save FPU state to signal context.  Signal handler
         * will "inherit" current FPU state.
         */
        err |= protected_save_fp_context(sc);

        return err;
}

static int restore_sigcontext32(struct pt_regs *regs,
                                struct sigcontext32 __user *sc)
{
        int err = 0;
        s32 treg;
        int i;

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

        err |= __get_user(regs->cp0_epc, &sc->sc_pc);
        err |= __get_user(regs->hi, &sc->sc_mdhi);
        err |= __get_user(regs->lo, &sc->sc_mdlo);
        if (cpu_has_dsp) {
                err |= __get_user(treg, &sc->sc_hi1); mthi1(treg);
                err |= __get_user(treg, &sc->sc_lo1); mtlo1(treg);
                err |= __get_user(treg, &sc->sc_hi2); mthi2(treg);
                err |= __get_user(treg, &sc->sc_lo2); mtlo2(treg);
                err |= __get_user(treg, &sc->sc_hi3); mthi3(treg);
                err |= __get_user(treg, &sc->sc_lo3); mtlo3(treg);
                err |= __get_user(treg, &sc->sc_dsp); wrdsp(treg, DSP_MASK);
        }

        for (i = 1; i < 32; i++)
                err |= __get_user(regs->regs[i], &sc->sc_regs[i]);

        return err ?: protected_restore_fp_context(sc);
}

static int setup_frame_32(void *sig_return, struct ksignal *ksig,
                          struct pt_regs *regs, sigset_t *set)
{
        struct sigframe32 __user *frame;
        int err = 0;

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

        err |= setup_sigcontext32(regs, &frame->sf_sc);
        err |= __copy_conv_sigset_to_user(&frame->sf_mask, set);

        if (err)
                return -EFAULT;

        /*
         * Arguments to signal handler:
         *
         *   a0 = signal number
         *   a1 = 0 (should be cause)
         *   a2 = pointer to struct sigcontext
         *
         * $25 and c0_epc point to the signal handler, $29 points to the
         * struct sigframe.
         */
        regs->regs[ 4] = ksig->sig;
        regs->regs[ 5] = 0;
        regs->regs[ 6] = (unsigned long) &frame->sf_sc;
        regs->regs[29] = (unsigned long) frame;
        regs->regs[31] = (unsigned long) sig_return;
        regs->cp0_epc = regs->regs[25] = (unsigned long) ksig->ka.sa.sa_handler;

        DEBUGP("SIG deliver (%s:%d): sp=0x%p pc=0x%lx ra=0x%lx\n",
               current->comm, current->pid,
               frame, regs->cp0_epc, regs->regs[31]);

        return 0;
}

asmlinkage void sys32_rt_sigreturn(nabi_no_regargs struct pt_regs regs)
{
        struct rt_sigframe32 __user *frame;
        sigset_t set;
        int sig;

        frame = (struct rt_sigframe32 __user *) regs.regs[29];
        if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
                goto badframe;
        if (__copy_conv_sigset_from_user(&set, &frame->rs_uc.uc_sigmask))
                goto badframe;

        set_current_blocked(&set);

        sig = restore_sigcontext32(&regs, &frame->rs_uc.uc_mcontext);
        if (sig < 0)
                goto badframe;
        else if (sig)
                force_sig(sig, current);

        if (compat_restore_altstack(&frame->rs_uc.uc_stack))
                goto badframe;

        /*
         * Don't let your children do this ...
         */
        __asm__ __volatile__(
                "move\t$29, %0\n\t"
                "j\tsyscall_exit"
                :/* no outputs */
                :"r" (&regs));
        /* Unreached */

badframe:
        force_sig(SIGSEGV, current);
}

static int setup_rt_frame_32(void *sig_return, struct ksignal *ksig,
                             struct pt_regs *regs, sigset_t *set)
{
        struct rt_sigframe32 __user *frame;
        int err = 0;

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

        /* Convert (siginfo_t -> compat_siginfo_t) and copy to user. */
        err |= copy_siginfo_to_user32(&frame->rs_info, &ksig->info);

        /* Create the ucontext.  */
        err |= __put_user(0, &frame->rs_uc.uc_flags);
        err |= __put_user(0, &frame->rs_uc.uc_link);
        err |= __compat_save_altstack(&frame->rs_uc.uc_stack, regs->regs[29]);
        err |= setup_sigcontext32(regs, &frame->rs_uc.uc_mcontext);
        err |= __copy_conv_sigset_to_user(&frame->rs_uc.uc_sigmask, set);

        if (err)
                return -EFAULT;

        /*
         * Arguments to signal handler:
         *
         *   a0 = signal number
         *   a1 = 0 (should be cause)
         *   a2 = pointer to ucontext
         *
         * $25 and c0_epc point to the signal handler, $29 points to
         * the struct rt_sigframe32.
         */
        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) frame;
        regs->regs[31] = (unsigned long) sig_return;
        regs->cp0_epc = regs->regs[25] = (unsigned long) ksig->ka.sa.sa_handler;

        DEBUGP("SIG deliver (%s:%d): sp=0x%p pc=0x%lx ra=0x%lx\n",
               current->comm, current->pid,
               frame, regs->cp0_epc, regs->regs[31]);

        return 0;
}

/*
 * o32 compatibility on 64-bit kernels, without DSP ASE
 */
struct mips_abi mips_abi_32 = {
        .setup_frame    = setup_frame_32,
        .setup_rt_frame = setup_rt_frame_32,
        .restart        = __NR_O32_restart_syscall,

        .off_sc_fpregs = offsetof(struct sigcontext32, sc_fpregs),
        .off_sc_fpc_csr = offsetof(struct sigcontext32, sc_fpc_csr),
        .off_sc_used_math = offsetof(struct sigcontext32, sc_used_math),

        .vdso           = &vdso_image_o32,
};


asmlinkage void sys32_sigreturn(nabi_no_regargs struct pt_regs regs)
{
        struct sigframe32 __user *frame;
        sigset_t blocked;
        int sig;

        frame = (struct sigframe32 __user *) regs.regs[29];
        if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
                goto badframe;
        if (__copy_conv_sigset_from_user(&blocked, &frame->sf_mask))
                goto badframe;

        set_current_blocked(&blocked);

        sig = restore_sigcontext32(&regs, &frame->sf_sc);
        if (sig < 0)
                goto badframe;
        else if (sig)
                force_sig(sig, current);

        /*
         * Don't let your children do this ...
         */
        __asm__ __volatile__(
                "move\t$29, %0\n\t"
                "j\tsyscall_exit"
                :/* no outputs */
                :"r" (&regs));
        /* Unreached */

badframe:
        force_sig(SIGSEGV, current);
}