/*
 * 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  Ralf Baechle
 * Copyright (C) 1999, 2000 Silicon Graphics, Inc.
 * Copyright (C) 2014, Imagination Technologies Ltd.
 */
#include <linux/cache.h>
#include <linux/context_tracking.h>
#include <linux/irqflags.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/personality.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/compiler.h>
#include <linux/syscalls.h>
#include <linux/uaccess.h>
#include <linux/tracehook.h>

#include <asm/abi.h>
#include <asm/asm.h>
#include <linux/bitops.h>
#include <asm/cacheflush.h>
#include <asm/fpu.h>
#include <asm/sim.h>
#include <asm/ucontext.h>
#include <asm/cpu-features.h>
#include <asm/war.h>
#include <asm/vdso.h>
#include <asm/dsp.h>
#include <asm/inst.h>

#include "signal-common.h"

static int (*save_fp_context)(struct sigcontext __user *sc);
static int (*restore_fp_context)(struct sigcontext __user *sc);

extern asmlinkage int _save_fp_context(struct sigcontext __user *sc);
extern asmlinkage int _restore_fp_context(struct sigcontext __user *sc);

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

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

/*
 * Thread saved context copy to/from a signal context presumed to be on the
 * user stack, and therefore accessed with appropriate macros from uaccess.h.
 */
static int copy_fp_to_sigcontext(struct sigcontext __user *sc)
{
        int i;
        int err = 0;

        for (i = 0; i < NUM_FPU_REGS; i++) {
                err |=
                    __put_user(get_fpr64(&current->thread.fpu.fpr[i], 0),
                               &sc->sc_fpregs[i]);
        }
        err |= __put_user(current->thread.fpu.fcr31, &sc->sc_fpc_csr);

        return err;
}

static int copy_fp_from_sigcontext(struct sigcontext __user *sc)
{
        int i;
        int err = 0;
        u64 fpr_val;

        for (i = 0; i < NUM_FPU_REGS; i++) {
                err |= __get_user(fpr_val, &sc->sc_fpregs[i]);
                set_fpr64(&current->thread.fpu.fpr[i], 0, fpr_val);
        }
        err |= __get_user(current->thread.fpu.fcr31, &sc->sc_fpc_csr);

        return err;
}

/*
 * Helper routines
 */
static int protected_save_fp_context(struct sigcontext __user *sc)
{
        int err;
#ifndef CONFIG_EVA
        while (1) {
                lock_fpu_owner();
                if (is_fpu_owner()) {
                        err = save_fp_context(sc);
                        unlock_fpu_owner();
                } else {
                        unlock_fpu_owner();
                        err = copy_fp_to_sigcontext(sc);
                }
                if (likely(!err))
                        break;
                /* touch the sigcontext and try again */
                err = __put_user(0, &sc->sc_fpregs[0]) |
                        __put_user(0, &sc->sc_fpregs[31]) |
                        __put_user(0, &sc->sc_fpc_csr);
                if (err)
                        break;  /* really bad sigcontext */
        }
#else
        /*
         * EVA does not have FPU EVA instructions so saving fpu context directly
         * does not work.
         */
        lose_fpu(1);
        err = save_fp_context(sc); /* this might fail */
#endif
        return err;
}

static int protected_restore_fp_context(struct sigcontext __user *sc)
{
        int err, tmp __maybe_unused;
#ifndef CONFIG_EVA
        while (1) {
                lock_fpu_owner();
                if (is_fpu_owner()) {
                        err = restore_fp_context(sc);
                        unlock_fpu_owner();
                } else {
                        unlock_fpu_owner();
                        err = copy_fp_from_sigcontext(sc);
                }
                if (likely(!err))
                        break;
                /* touch the sigcontext and try again */
                err = __get_user(tmp, &sc->sc_fpregs[0]) |
                        __get_user(tmp, &sc->sc_fpregs[31]) |
                        __get_user(tmp, &sc->sc_fpc_csr);
                if (err)
                        break;  /* really bad sigcontext */
        }
#else
        /*
         * EVA does not have FPU EVA instructions so restoring fpu context
         * directly does not work.
         */
        lose_fpu(0);
        err = restore_fp_context(sc); /* this might fail */
#endif
        return err;
}

int setup_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
{
        int err = 0;
        int i;
        unsigned int used_math;

        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]);

#ifdef CONFIG_CPU_HAS_SMARTMIPS
        err |= __put_user(regs->acx, &sc->sc_acx);
#endif
        err |= __put_user(regs->hi, &sc->sc_mdhi);
        err |= __put_user(regs->lo, &sc->sc_mdlo);
        if (cpu_has_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);
                err |= __put_user(rddsp(DSP_MASK), &sc->sc_dsp);
        }

        used_math = !!used_math();
        err |= __put_user(used_math, &sc->sc_used_math);

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

int fpcsr_pending(unsigned int __user *fpcsr)
{
        int err, sig = 0;
        unsigned int csr, enabled;

        err = __get_user(csr, fpcsr);
        enabled = FPU_CSR_UNI_X | ((csr & FPU_CSR_ALL_E) << 5);
        /*
         * If the signal handler set some FPU exceptions, clear it and
         * send SIGFPE.
         */
        if (csr & enabled) {
                csr &= ~enabled;
                err |= __put_user(csr, fpcsr);
                sig = SIGFPE;
        }
        return err ?: sig;
}

static int
check_and_restore_fp_context(struct sigcontext __user *sc)
{
        int err, sig;

        err = sig = fpcsr_pending(&sc->sc_fpc_csr);
        if (err > 0)
                err = 0;
        err |= protected_restore_fp_context(sc);
        return err ?: sig;
}

int restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
{
        unsigned int used_math;
        unsigned long treg;
        int err = 0;
        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);

#ifdef CONFIG_CPU_HAS_SMARTMIPS
        err |= __get_user(regs->acx, &sc->sc_acx);
#endif
        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]);

        err |= __get_user(used_math, &sc->sc_used_math);
        conditional_used_math(used_math);

        if (used_math) {
                /* restore fpu context if we have used it before */
                if (!err)
                        err = check_and_restore_fp_context(sc);
        } else {
                /* signal handler may have used FPU.  Give it up. */
                lose_fpu(0);
        }

        return err;
}

void __user *get_sigframe(struct ksignal *ksig, struct pt_regs *regs,
                          size_t frame_size)
{
        unsigned long sp;

        /* Default to using normal stack */
        sp = regs->regs[29];

        /*
         * FPU emulator may have it's own trampoline active just
         * above the user stack, 16-bytes before the next lowest
         * 16 byte boundary.  Try to avoid trashing it.
         */
        sp -= 32;

        sp = sigsp(sp, ksig);

        return (void __user *)((sp - frame_size) & (ICACHE_REFILLS_WORKAROUND_WAR ? ~(cpu_icache_line_size()-1) : ALMASK));
}

/*
 * Atomically swap in the new signal mask, and wait for a signal.
 */

#ifdef CONFIG_TRAD_SIGNALS
SYSCALL_DEFINE1(sigsuspend, sigset_t __user *, uset)
{
        return sys_rt_sigsuspend(uset, sizeof(sigset_t));
}
#endif

#ifdef CONFIG_TRAD_SIGNALS
SYSCALL_DEFINE3(sigaction, int, sig, const struct sigaction __user *, act,
        struct sigaction __user *, oact)
{
        struct k_sigaction new_ka, old_ka;
        int ret;
        int err = 0;

        if (act) {
                old_sigset_t mask;

                if (!access_ok(VERIFY_READ, act, sizeof(*act)))
                        return -EFAULT;
                err |= __get_user(new_ka.sa.sa_handler, &act->sa_handler);
                err |= __get_user(new_ka.sa.sa_flags, &act->sa_flags);
                err |= __get_user(mask, &act->sa_mask.sig[0]);
                if (err)
                        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)))
                        return -EFAULT;
                err |= __put_user(old_ka.sa.sa_flags, &oact->sa_flags);
                err |= __put_user(old_ka.sa.sa_handler, &oact->sa_handler);
                err |= __put_user(old_ka.sa.sa_mask.sig[0], oact->sa_mask.sig);
                err |= __put_user(0, &oact->sa_mask.sig[1]);
                err |= __put_user(0, &oact->sa_mask.sig[2]);
                err |= __put_user(0, &oact->sa_mask.sig[3]);
                if (err)
                        return -EFAULT;
        }

        return ret;
}
#endif

#ifdef CONFIG_TRAD_SIGNALS
asmlinkage void sys_sigreturn(nabi_no_regargs struct pt_regs regs)
{
        struct sigframe __user *frame;
        sigset_t blocked;
        int sig;

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

        set_current_blocked(&blocked);

        sig = restore_sigcontext(&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);
}
#endif /* CONFIG_TRAD_SIGNALS */

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

        frame = (struct rt_sigframe __user *) regs.regs[29];
        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;

        /*
         * 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);
}

#ifdef CONFIG_TRAD_SIGNALS
static int setup_frame(void *sig_return, struct ksignal *ksig,
                       struct pt_regs *regs, sigset_t *set)
{
        struct sigframe __user *frame;
        int err = 0;

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

        err |= setup_sigcontext(regs, &frame->sf_sc);
        err |= __copy_to_user(&frame->sf_mask, set, sizeof(*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;
}
#endif

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

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

        /* Create siginfo.  */
        err |= copy_siginfo_to_user(&frame->rs_info, &ksig->info);

        /* Create the ucontext.  */
        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[29]);
        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;

        /*
         * 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_sigframe.
         */
        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;
}

struct mips_abi mips_abi = {
#ifdef CONFIG_TRAD_SIGNALS
        .setup_frame    = setup_frame,
        .signal_return_offset = offsetof(struct mips_vdso, signal_trampoline),
#endif
        .setup_rt_frame = setup_rt_frame,
        .rt_signal_return_offset =
                offsetof(struct mips_vdso, rt_signal_trampoline),
        .restart        = __NR_restart_syscall
};

static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
{
        sigset_t *oldset = sigmask_to_save();
        int ret;
        struct mips_abi *abi = current->thread.abi;
#ifdef CONFIG_CPU_MICROMIPS
        void *vdso;
        unsigned long tmp = (unsigned long)current->mm->context.vdso;

        set_isa16_mode(tmp);
        vdso = (void *)tmp;
#else
        void *vdso = current->mm->context.vdso;
#endif

        if (regs->regs[0]) {
                switch(regs->regs[2]) {
                case ERESTART_RESTARTBLOCK:
                case ERESTARTNOHAND:
                        regs->regs[2] = EINTR;
                        break;
                case ERESTARTSYS:
                        if (!(ksig->ka.sa.sa_flags & SA_RESTART)) {
                                regs->regs[2] = EINTR;
                                break;
                        }
                /* fallthrough */
                case ERESTARTNOINTR:
                        regs->regs[7] = regs->regs[26];
                        regs->regs[2] = regs->regs[0];
                        regs->cp0_epc -= 4;
                }

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

        if (sig_uses_siginfo(&ksig->ka))
                ret = abi->setup_rt_frame(vdso + abi->rt_signal_return_offset,
                                          ksig, regs, oldset);
        else
                ret = abi->setup_frame(vdso + abi->signal_return_offset, ksig,
                                       regs, oldset);

        signal_setup_done(ret, ksig, 0);
}

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

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

        if (regs->regs[0]) {
                switch (regs->regs[2]) {
                case ERESTARTNOHAND:
                case ERESTARTSYS:
                case ERESTARTNOINTR:
                        regs->regs[2] = regs->regs[0];
                        regs->regs[7] = regs->regs[26];
                        regs->cp0_epc -= 4;
                        break;

                case ERESTART_RESTARTBLOCK:
                        regs->regs[2] = current->thread.abi->restart;
                        regs->regs[7] = regs->regs[26];
                        regs->cp0_epc -= 4;
                        break;
                }
                regs->regs[0] = 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)
{
        local_irq_enable();

        user_exit();

        /* 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);
        }

        user_enter();
}

#ifdef CONFIG_SMP
#ifndef CONFIG_EVA
static int smp_save_fp_context(struct sigcontext __user *sc)
{
        return raw_cpu_has_fpu
               ? _save_fp_context(sc)
               : copy_fp_to_sigcontext(sc);
}

static int smp_restore_fp_context(struct sigcontext __user *sc)
{
        return raw_cpu_has_fpu
               ? _restore_fp_context(sc)
               : copy_fp_from_sigcontext(sc);
}
#endif /* CONFIG_EVA */
#endif

static int signal_setup(void)
{
#ifndef CONFIG_EVA
#ifdef CONFIG_SMP
        /* For now just do the cpu_has_fpu check when the functions are invoked */
        save_fp_context = smp_save_fp_context;
        restore_fp_context = smp_restore_fp_context;
#else
        if (cpu_has_fpu) {
                save_fp_context = _save_fp_context;
                restore_fp_context = _restore_fp_context;
        } else {
                save_fp_context = copy_fp_to_sigcontext;
                restore_fp_context = copy_fp_from_sigcontext;
        }
#endif /* CONFIG_SMP */
#else
        save_fp_context = copy_fp_to_sigcontext;
        restore_fp_context = copy_fp_from_sigcontext;
#endif

        return 0;
}

arch_initcall(signal_setup);