/*
 * 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.
 */
#include <linux/cache.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 <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 "signal-common.h"

/*
 * Horribly complicated - with the bloody RM9000 workarounds enabled
 * the signal trampolines is moving to the end of the structure so we can
 * increase the alignment without breaking software compatibility.
 */
#if ICACHE_REFILLS_WORKAROUND_WAR == 0

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

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

#else

struct sigframe {
        u32 sf_ass[4];                  /* argument save space for o32 */
        u32 sf_pad[2];
        struct sigcontext sf_sc;        /* hw context */
        sigset_t sf_mask;
        u32 sf_code[8] ____cacheline_aligned;   /* signal trampoline */
};

struct rt_sigframe {
        u32 rs_ass[4];                  /* argument save space for o32 */
        u32 rs_pad[2];
        struct siginfo rs_info;
        struct ucontext rs_uc;
        u32 rs_code[8] ____cacheline_aligned;   /* signal trampoline */
};

#endif

/*
 * Helper routines
 */
static int protected_save_fp_context(struct sigcontext __user *sc)
{
        int err;
        while (1) {
                lock_fpu_owner();
                own_fpu_inatomic(1);
                err = save_fp_context(sc); /* this might fail */
                unlock_fpu_owner();
                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 */
        }
        return err;
}

static int protected_restore_fp_context(struct sigcontext __user *sc)
{
        int err, tmp;
        while (1) {
                lock_fpu_owner();
                own_fpu_inatomic(0);
                err = restore_fp_context(sc); /* this might fail */
                unlock_fpu_owner();
                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 */
        }
        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_thread_info()->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 k_sigaction *ka, 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;

        /* This is the X/Open sanctioned signal stack switching.  */
        if ((ka->sa.sa_flags & SA_ONSTACK) && (sas_ss_flags (sp) == 0))
                sp = current->sas_ss_sp + current->sas_ss_size;

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

int install_sigtramp(unsigned int __user *tramp, unsigned int syscall)
{
        int err;

        /*
         * Set up the return code ...
         *
         *         li      v0, __NR__foo_sigreturn
         *         syscall
         */

        err = __put_user(0x24020000 + syscall, tramp + 0);
        err |= __put_user(0x0000000c         , tramp + 1);
        if (ICACHE_REFILLS_WORKAROUND_WAR) {
                err |= __put_user(0, tramp + 2);
                err |= __put_user(0, tramp + 3);
                err |= __put_user(0, tramp + 4);
                err |= __put_user(0, tramp + 5);
                err |= __put_user(0, tramp + 6);
                err |= __put_user(0, tramp + 7);
        }
        flush_cache_sigtramp((unsigned long) tramp);

        return err;
}

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

#ifdef CONFIG_TRAD_SIGNALS
asmlinkage int sys_sigsuspend(nabi_no_regargs struct pt_regs regs)
{
        sigset_t newset;
        sigset_t __user *uset;

        uset = (sigset_t __user *) regs.regs[4];
        if (copy_from_user(&newset, uset, sizeof(sigset_t)))
                return -EFAULT;
        sigdelsetmask(&newset, ~_BLOCKABLE);

        spin_lock_irq(&current->sighand->siglock);
        current->saved_sigmask = current->blocked;
        current->blocked = newset;
        recalc_sigpending();
        spin_unlock_irq(&current->sighand->siglock);

        current->state = TASK_INTERRUPTIBLE;
        schedule();
        set_thread_flag(TIF_RESTORE_SIGMASK);
        return -ERESTARTNOHAND;
}
#endif

asmlinkage int sys_rt_sigsuspend(nabi_no_regargs struct pt_regs regs)
{
        sigset_t newset;
        sigset_t __user *unewset;
        size_t sigsetsize;

        /* XXX Don't preclude handling different sized sigset_t's.  */
        sigsetsize = regs.regs[5];
        if (sigsetsize != sizeof(sigset_t))
                return -EINVAL;

        unewset = (sigset_t __user *) regs.regs[4];
        if (copy_from_user(&newset, unewset, sizeof(newset)))
                return -EFAULT;
        sigdelsetmask(&newset, ~_BLOCKABLE);

        spin_lock_irq(&current->sighand->siglock);
        current->saved_sigmask = current->blocked;
        current->blocked = newset;
        recalc_sigpending();
        spin_unlock_irq(&current->sighand->siglock);

        current->state = TASK_INTERRUPTIBLE;
        schedule();
        set_thread_flag(TIF_RESTORE_SIGMASK);
        return -ERESTARTNOHAND;
}

#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

asmlinkage int sys_sigaltstack(nabi_no_regargs 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[29];

        return do_sigaltstack(uss, uoss, usp);
}

#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;

        sigdelsetmask(&blocked, ~_BLOCKABLE);
        spin_lock_irq(&current->sighand->siglock);
        current->blocked = blocked;
        recalc_sigpending();
        spin_unlock_irq(&current->sighand->siglock);

        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;
        stack_t st;
        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;

        sigdelsetmask(&set, ~_BLOCKABLE);
        spin_lock_irq(&current->sighand->siglock);
        current->blocked = set;
        recalc_sigpending();
        spin_unlock_irq(&current->sighand->siglock);

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

        if (__copy_from_user(&st, &frame->rs_uc.uc_stack, sizeof(st)))
                goto badframe;
        /* It is more difficult to avoid calling this function than to
           call it and ignore errors.  */
        do_sigaltstack((stack_t __user *)&st, NULL, regs.regs[29]);

        /*
         * 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(struct k_sigaction * ka, struct pt_regs *regs,
        int signr, sigset_t *set)
{
        struct sigframe __user *frame;
        int err = 0;

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

        err |= install_sigtramp(frame->sf_code, __NR_sigreturn);

        err |= setup_sigcontext(regs, &frame->sf_sc);
        err |= __copy_to_user(&frame->sf_mask, set, sizeof(*set));
        if (err)
                goto give_sigsegv;

        /*
         * 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] = signr;
        regs->regs[ 5] = 0;
        regs->regs[ 6] = (unsigned long) &frame->sf_sc;
        regs->regs[29] = (unsigned long) frame;
        regs->regs[31] = (unsigned long) frame->sf_code;
        regs->cp0_epc = regs->regs[25] = (unsigned long) 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;

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

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;

        err |= install_sigtramp(frame->rs_code, __NR_rt_sigreturn);

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

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

        /*
         * 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] = signr;
        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) frame->rs_code;
        regs->cp0_epc = regs->regs[25] = (unsigned long) 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;

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

struct mips_abi mips_abi = {
#ifdef CONFIG_TRAD_SIGNALS
        .setup_frame    = setup_frame,
#endif
        .setup_rt_frame = setup_rt_frame,
        .restart        = __NR_restart_syscall
};

static int handle_signal(unsigned long sig, siginfo_t *info,
        struct k_sigaction *ka, sigset_t *oldset, struct pt_regs *regs)
{
        int ret;

        switch(regs->regs[0]) {
        case ERESTART_RESTARTBLOCK:
        case ERESTARTNOHAND:
                regs->regs[2] = EINTR;
                break;
        case ERESTARTSYS:
                if (!(ka->sa.sa_flags & SA_RESTART)) {
                        regs->regs[2] = EINTR;
                        break;
                }
        /* fallthrough */
        case ERESTARTNOINTR:            /* Userland will reload $v0.  */
                regs->regs[7] = regs->regs[26];
                regs->cp0_epc -= 8;
        }

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

        if (sig_uses_siginfo(ka))
                ret = current->thread.abi->setup_rt_frame(ka, regs, sig, oldset, info);
        else
                ret = current->thread.abi->setup_frame(ka, regs, sig, oldset);

        spin_lock_irq(&current->sighand->siglock);
        sigorsets(&current->blocked, &current->blocked, &ka->sa.sa_mask);
        if (!(ka->sa.sa_flags & SA_NODEFER))
                sigaddset(&current->blocked, sig);
        recalc_sigpending();
        spin_unlock_irq(&current->sighand->siglock);

        return ret;
}

static void do_signal(struct pt_regs *regs)
{
        struct k_sigaction ka;
        sigset_t *oldset;
        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;

        if (test_thread_flag(TIF_RESTORE_SIGMASK))
                oldset = &current->saved_sigmask;
        else
                oldset = &current->blocked;

        signr = get_signal_to_deliver(&info, &ka, regs, NULL);
        if (signr > 0) {
                /* Whee!  Actually deliver the signal.  */
                if (handle_signal(signr, &info, &ka, oldset, regs) == 0) {
                        /*
                         * A signal was successfully delivered; the saved
                         * sigmask will have been stored in the signal frame,
                         * and will be restored by sigreturn, so we can simply
                         * clear the TIF_RESTORE_SIGMASK flag.
                         */
                        if (test_thread_flag(TIF_RESTORE_SIGMASK))
                                clear_thread_flag(TIF_RESTORE_SIGMASK);
                }

                return;
        }

        /*
         * Who's code doesn't conform to the restartable syscall convention
         * dies here!!!  The li instruction, a single machine instruction,
         * must directly be followed by the syscall instruction.
         */
        if (regs->regs[0]) {
                if (regs->regs[2] == ERESTARTNOHAND ||
                    regs->regs[2] == ERESTARTSYS ||
                    regs->regs[2] == ERESTARTNOINTR) {
                        regs->regs[7] = regs->regs[26];
                        regs->cp0_epc -= 8;
                }
                if (regs->regs[2] == ERESTART_RESTARTBLOCK) {
                        regs->regs[2] = current->thread.abi->restart;
                        regs->regs[7] = regs->regs[26];
                        regs->cp0_epc -= 4;
                }
                regs->regs[0] = 0;      /* Don't deal with this again.  */
        }

        /*
         * If there's no signal to deliver, we just put the saved sigmask
         * back
         */
        if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
                clear_thread_flag(TIF_RESTORE_SIGMASK);
                sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
        }
}

/*
 * 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 | _TIF_RESTORE_SIGMASK))
                do_signal(regs);
}