/*
 *  linux/arch/ppc64/kernel/signal.c
 *
 *  PowerPC version 
 *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
 *
 *  Derived from "arch/i386/kernel/signal.c"
 *    Copyright (C) 1991, 1992 Linus Torvalds
 *    1997-11-28  Modified for POSIX.1b signals by Richard Henderson
 *
 *  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.
 */

#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/smp_lock.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/stddef.h>
#include <linux/elf.h>
#include <asm/ppc32.h>
#include <asm/sigcontext.h>
#include <asm/ucontext.h>
#include <asm/uaccess.h>
#include <asm/pgtable.h>
#include <asm/unistd.h>
#include <asm/processor.h>

#define DEBUG_SIG 0

#define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))

#ifndef MIN
#define MIN(a,b) (((a) < (b)) ? (a) : (b))
#endif

#define GP_REGS_SIZE    MIN(sizeof(elf_gregset_t), sizeof(struct pt_regs))
#define FP_REGS_SIZE    sizeof(elf_fpregset_t)

#define TRAMP_TRACEBACK 3
#define TRAMP_SIZE      6

/*
 * When we have signals to deliver, we set up on the user stack,
 * going down from the original stack pointer:
 *      1) a sigframe/rt_sigframe struct which contains the sigcontext/ucontext 
 *      2) a gap of __SIGNAL_FRAMESIZE bytes which acts as a dummy caller
 *         frame for the signal handler.
 */

struct sigframe {
        /* sys_sigreturn requires the sigcontext be the first field */
        struct sigcontext sc;
        unsigned int tramp[TRAMP_SIZE];
        /* 64 bit ABI allows for 288 bytes below sp before decrementing it. */
        char abigap[288];
};

struct rt_sigframe {
        /* sys_rt_sigreturn requires the ucontext be the first field */
        struct ucontext uc;
        unsigned long _unused[2];
        unsigned int tramp[TRAMP_SIZE];
        struct siginfo *pinfo;
        void *puc;
        struct siginfo info;
        /* 64 bit ABI allows for 288 bytes below sp before decrementing it. */
        char abigap[288];
};

extern long sys_wait4(pid_t pid, unsigned int *stat_addr,
                     int options, /*unsigned long*/ struct rusage *ru);

int
copy_siginfo_to_user(siginfo_t *to, siginfo_t *from)
{
        if (!access_ok (VERIFY_WRITE, to, sizeof(siginfo_t)))
                return -EFAULT;
        if (from->si_code < 0)
                return __copy_to_user(to, from, sizeof(siginfo_t));
        else {
                int err;

                /* If you change siginfo_t structure, please be sure
                   this code is fixed accordingly.
                   It should never copy any pad contained in the structure
                   to avoid security leaks, but must copy the generic
                   3 ints plus the relevant union member.  */
                err = __put_user(from->si_signo, &to->si_signo);
                err |= __put_user(from->si_errno, &to->si_errno);
                err |= __put_user((short)from->si_code, &to->si_code);
                /* First 32bits of unions are always present.  */
                err |= __put_user(from->si_pid, &to->si_pid);
                switch (from->si_code >> 16) {
                case __SI_FAULT >> 16:
                        err |= __put_user(from->si_addr, &to->si_addr);
                        break;
                case __SI_CHLD >> 16:
                        err |= __put_user(from->si_utime, &to->si_utime);
                        err |= __put_user(from->si_stime, &to->si_stime);
                        err |= __put_user(from->si_status, &to->si_status);
                default:
                        err |= __put_user(from->si_uid, &to->si_uid);
                        break;
                /* case __SI_RT: This is not generated by the kernel as of now.  */
                }
                return err;
        }
}

int do_signal(sigset_t *oldset, struct pt_regs *regs);

/*
 * Atomically swap in the new signal mask, and wait for a signal.
 */
asmlinkage long
sys_sigsuspend(old_sigset_t mask, int p2, int p3, int p4, int p6, int p7,
               struct pt_regs *regs)
{
        sigset_t saveset;

        mask &= _BLOCKABLE;
        spin_lock_irq(&current->sigmask_lock);
        saveset = current->blocked;
        siginitset(&current->blocked, mask);
        recalc_sigpending(current);
        spin_unlock_irq(&current->sigmask_lock);

        regs->result = -EINTR;
        regs->gpr[3] = EINTR;
        regs->ccr |= 0x10000000;
        while (1) {
                set_current_state(TASK_INTERRUPTIBLE);
                schedule();
                if (do_signal(&saveset, regs))
                        /*
                         * If a signal handler needs to be called,
                         * do_signal() has set R3 to the signal number (the
                         * first argument of the signal handler), so don't
                         * overwrite that with EINTR !
                         * In the other cases, do_signal() doesn't touch 
                         * R3, so it's still set to -EINTR (see above).
                         */
                        return regs->gpr[3];
        }
}

asmlinkage long
sys_rt_sigsuspend(sigset_t *unewset, size_t sigsetsize, int p3, int p4, int p6,
                  int p7, struct pt_regs *regs)
{
        sigset_t saveset, newset;

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

        if (copy_from_user(&newset, unewset, sizeof(newset)))
                return -EFAULT;
        sigdelsetmask(&newset, ~_BLOCKABLE);

        spin_lock_irq(&current->sigmask_lock);
        saveset = current->blocked;
        current->blocked = newset;
        recalc_sigpending(current);
        spin_unlock_irq(&current->sigmask_lock);

        regs->result = -EINTR;
        regs->gpr[3] = EINTR;
        regs->ccr |= 0x10000000;
        while (1) {
                current->state = TASK_INTERRUPTIBLE;
                schedule();
                if (do_signal(&saveset, regs))
                        return regs->gpr[3];
        }
}

asmlinkage long
sys_sigaltstack(const stack_t *uss, stack_t *uoss, unsigned long r5,
                unsigned long r6, unsigned long r7, unsigned long r8,
                struct pt_regs *regs)
{
        return do_sigaltstack(uss, uoss, regs->gpr[1]);
}

asmlinkage long
sys_sigaction(int sig, const struct old_sigaction *act,
              struct old_sigaction *oact)
{
        struct k_sigaction new_ka, old_ka;
        int ret;

        if (act) {
                old_sigset_t mask;

                if (verify_area(VERIFY_READ, act, sizeof(*act)) ||
                    __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
                    __get_user(new_ka.sa.sa_restorer, &act->sa_restorer))
                        return -EFAULT;
                __get_user(new_ka.sa.sa_flags, &act->sa_flags);
                __get_user(mask, &act->sa_mask);
                siginitset(&new_ka.sa.sa_mask, mask);
        }

        ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
        if (!ret && oact) {
                if (verify_area(VERIFY_WRITE, oact, sizeof(*oact)) ||
                    __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
                    __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer))
                        return -EFAULT;
                __put_user(old_ka.sa.sa_flags, &oact->sa_flags);
                __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask);
        }

        return ret;
}

/*
 * Set up the sigcontext for the signal frame.
 */

static int
setup_sigcontext(struct sigcontext *sc, struct pt_regs *regs,
                 int signr, sigset_t *set, unsigned long handler)
{
        int err = 0;

        if (regs->msr & MSR_FP)
                giveup_fpu(current);
        err |= __put_user(&sc->gp_regs, &sc->regs);
        err |= __copy_to_user(&sc->gp_regs, regs, GP_REGS_SIZE);
        err |= __copy_to_user(&sc->fp_regs, &current->thread.fpr, FP_REGS_SIZE);
        current->thread.fpscr = 0;

        err |= __put_user(signr, &sc->signal);
        err |= __put_user(handler, &sc->handler);
        if (set != NULL)
                err |=  __put_user(set->sig[0], &sc->oldmask);

        return err;
}

/*
 * Restore the sigcontext from the signal frame.
 */

static int
restore_sigcontext(struct pt_regs *regs, sigset_t *set, struct sigcontext *sc)
{
        unsigned int err = 0;
        int i;
        elf_greg_t *gregs = (elf_greg_t *)regs;
        unsigned long msr;

        /* copy up to but not including MSR */
        err |= __copy_from_user(regs, &sc->gp_regs,
                                PT_MSR * sizeof(elf_greg_t));
        /* get the MSR value from the stack but don't put it in regs->msr */
        err |= __get_user(msr, &sc->gp_regs[PT_MSR]);
        /* copy from orig_r3 (the word after the MSR) to the end,
         * but don't copy softe */
        for (i = PT_ORIG_R3; err == 0 && i <= PT_RESULT; ++i)
                if (i != PT_SOFTE)
                        err |= __get_user(gregs[i], &sc->gp_regs[i]);

        /* make the process reload FP regs if it executes an FP instr */
        regs->msr &= ~(MSR_FP | MSR_FE0 | MSR_FE1);
#ifndef CONFIG_SMP
        if (last_task_used_math == current)
                last_task_used_math = NULL;
#endif
        err |= __copy_from_user(&current->thread.fpr, &sc->fp_regs, FP_REGS_SIZE);

        /* restore the signal mask */
        if (set != NULL)
                err |=  __get_user(set->sig[0], &sc->oldmask);

        return err;
}

/*
 * Allocate space for the signal frame
 */
static inline void *
get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size)
{
        unsigned long newsp;

        /* Default to using normal stack */
        newsp = regs->gpr[1];

        if (ka->sa.sa_flags & SA_ONSTACK) {
                if (! on_sig_stack(regs->gpr[1]))
                        newsp = (current->sas_ss_sp + current->sas_ss_size);
        }

        /* The ABI requires quadword alignment for the stack. */
        return (void *)((newsp - frame_size) & -16ul);

}

static int
setup_trampoline(unsigned int syscall, unsigned int *tramp)
{
        int i, err = 0;

        /* addi r1, r1, __SIGNAL_FRAMESIZE  # Pop the dummy stackframe */
        err |= __put_user(0x38210000UL | (__SIGNAL_FRAMESIZE & 0xffff), &tramp[0]);
        /* li r0, __NR_[rt_]sigreturn| */
        err |= __put_user(0x38000000UL | (syscall & 0xffff), &tramp[1]);
        /* sc */
        err |= __put_user(0x44000002UL, &tramp[2]);

        /* Minimal traceback info */
        for (i=TRAMP_TRACEBACK; i < TRAMP_SIZE ;i++)
                err |= __put_user(0, &tramp[i]);

        if (!err)
                flush_icache_range((unsigned long) &tramp[0],
                           (unsigned long) &tramp[TRAMP_SIZE]);

        return err;
}


asmlinkage int
sys_rt_sigreturn(unsigned long r3, unsigned long r4, unsigned long r5,
                 unsigned long r6, unsigned long r7, unsigned long r8,
                 struct pt_regs *regs)
{
        struct ucontext *uc = (struct ucontext *)regs->gpr[1];
        sigset_t set;
        stack_t st;

        if (verify_area(VERIFY_READ, uc, sizeof(*uc)))
                goto badframe;

        if (__copy_from_user(&set, &uc->uc_sigmask, sizeof(set)))
                goto badframe;

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

        if (restore_sigcontext(regs, NULL, &uc->uc_mcontext))
                goto badframe;

        if (__copy_from_user(&st, &uc->uc_stack, sizeof(st)))
                goto badframe;

        /* This function sets back the stack flags into
           the current task structure.  */
        sys_sigaltstack(&st, NULL, 0, 0, 0, 0, regs);

        return regs->result;

badframe:
        do_exit(SIGSEGV);
}

static void
setup_rt_frame(int signr, struct k_sigaction *ka, siginfo_t *info,
                sigset_t *set, struct pt_regs *regs)
{
        /* Handler is *really* a pointer to the function descriptor for
         * the signal routine.  The first entry in the function
         * descriptor is the entry address of signal and the second
         * entry is the TOC value we need to use.
         */
        func_descr_t *funct_desc_ptr;
        struct rt_sigframe *frame;
        unsigned long newsp;
        int err = 0;

        frame = get_sigframe(ka, regs, sizeof(*frame));

        if (verify_area(VERIFY_WRITE, frame, sizeof(*frame)))
                goto give_sigsegv;

        err |= __put_user(&frame->info, &frame->pinfo);
        err |= __put_user(&frame->uc, &frame->puc);
        err |= copy_siginfo_to_user(&frame->info, info);
        if (err)
                goto give_sigsegv;

        /* Create the ucontext.  */
        err |= __put_user(0, &frame->uc.uc_flags);
        err |= __put_user(0, &frame->uc.uc_link);
        err |= __put_user(current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
        err |= __put_user(sas_ss_flags(regs->gpr[1]),
                          &frame->uc.uc_stack.ss_flags);
        err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
        err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, signr, NULL,
                                (unsigned long)ka->sa.sa_handler);
        err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
        if (err)
                goto give_sigsegv;

        /* Set up to return from userspace. */
        err |= setup_trampoline(__NR_rt_sigreturn, &frame->tramp[0]);
        if (err)
                goto give_sigsegv;

        funct_desc_ptr = (func_descr_t *) ka->sa.sa_handler;

        /* Allocate a dummy caller frame for the signal handler. */
        newsp = (unsigned long)frame - __SIGNAL_FRAMESIZE;
        err |= put_user(0, (unsigned long *)newsp);

        /* Set up "regs" so we "return" to the signal handler. */
        err |= get_user(regs->nip, &funct_desc_ptr->entry);
        regs->link = (unsigned long) &frame->tramp[0];
        regs->gpr[1] = newsp;
        err |= get_user(regs->gpr[2], &funct_desc_ptr->toc);
        regs->gpr[3] = signr;
        err |= get_user(regs->gpr[4], (unsigned long *)&frame->pinfo);
        err |= get_user(regs->gpr[5], (unsigned long *)&frame->puc);
        regs->gpr[6] = (unsigned long) frame;
        if (err)
                goto give_sigsegv;

        return;

give_sigsegv:
#if DEBUG_SIG
        printk("badframe in setup_rt_frame, regs=%p frame=%p, newsp=0x%lx\n",
                regs, frame, newsp);
#endif
        do_exit(SIGSEGV);
}

/*
 * Do a signal return; undo the signal stack.
 */
asmlinkage long
sys_sigreturn(unsigned long r3, unsigned long r4, unsigned long r5,
              unsigned long r6, unsigned long r7, unsigned long r8,
              struct pt_regs *regs)
{
        struct sigcontext *sc = (struct sigcontext *)regs->gpr[1];
        sigset_t set;

        if (verify_area(VERIFY_READ, sc, sizeof(*sc)))
                goto badframe;

        if (restore_sigcontext(regs, &set, sc))
                goto badframe;

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

        return regs->result;

badframe:
        do_exit(SIGSEGV);
}       


static void
setup_frame(int signr, struct k_sigaction *ka, sigset_t *set,
            struct pt_regs *regs)
{
        /* Handler is *really* a pointer to the function descriptor for
         * the signal routine.  The first entry in the function
         * descriptor is the entry address of signal and the second
         * entry is the TOC value we need to use.
         */
        func_descr_t *funct_desc_ptr;
        struct sigframe *frame;
        unsigned long newsp;
        int err = 0;

        frame = get_sigframe(ka, regs, sizeof(*frame));

        if (verify_area(VERIFY_WRITE, frame, sizeof(*frame)))
                goto badframe;

        err |= setup_sigcontext(&frame->sc, regs, signr, set,
                                (unsigned long)ka->sa.sa_handler);

        /* Set up to return from userspace. */
        err |= setup_trampoline(__NR_sigreturn, &frame->tramp[0]);
        if (err)
                goto badframe;

        funct_desc_ptr = (func_descr_t *) ka->sa.sa_handler;

        /* Allocate a dummy caller frame for the signal handler. */
        newsp = (unsigned long)frame - __SIGNAL_FRAMESIZE;
        err |= put_user(0, (unsigned long *)newsp);

        /* Set up "regs" so we "return" to the signal handler. */
        err |= get_user(regs->nip, &funct_desc_ptr->entry);
        regs->link = (unsigned long) &frame->tramp[0];
        regs->gpr[1] = newsp;
        err |= get_user(regs->gpr[2], &funct_desc_ptr->toc);
        regs->gpr[3] = signr;
        regs->gpr[4] = (unsigned long) &frame->sc;
        if (err)
                goto badframe;

        return;

badframe:
#if DEBUG_SIG
        printk("badframe in setup_frame, regs=%p frame=%p newsp=%lx\n",
               regs, frame, newsp);
#endif
        do_exit(SIGSEGV);
}

/*
 * OK, we're invoking a handler
 */
static void
handle_signal(unsigned long sig, struct k_sigaction *ka,
              siginfo_t *info, sigset_t *oldset, struct pt_regs *regs)
{
        /* Set up Signal Frame */
        if (ka->sa.sa_flags & SA_SIGINFO)
                setup_rt_frame(sig, ka, info, oldset, regs);
        else
                setup_frame(sig, ka, oldset, regs);

        if (ka->sa.sa_flags & SA_ONESHOT)
                ka->sa.sa_handler = SIG_DFL;

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

static inline void
syscall_restart(struct pt_regs *regs, struct k_sigaction *ka)
{
        switch ((int)regs->result) {
                case -ERESTARTNOHAND:
                        /* ERESTARTNOHAND means that the syscall should only
                           be restarted if there was no handler for the signal,
                           and since we only get here if there is a handler,
                           we dont restart */
                        regs->result = -EINTR;
                        break;

                case -ERESTARTSYS:
                        /* ERESTARTSYS means to restart the syscall if there is
                           no handler or the handler was registered with SA_RESTART */
                        if (!(ka->sa.sa_flags & SA_RESTART)) {
                                regs->result = -EINTR;
                                break;
                        }
                /* fallthrough */
                case -ERESTARTNOINTR:
                        /* ERESTARTNOINTR means that the syscall should be
                           called again after the signal handler returns */
                        regs->gpr[3] = regs->orig_gpr3;
                        regs->nip -= 4;
                        regs->result = 0;
        }
}

static int
get_signal_to_deliver(siginfo_t *info, struct pt_regs *regs)
{
        for (;;) {
                unsigned long signr;
                struct k_sigaction *ka;

                spin_lock_irq(&current->sigmask_lock);
                signr = dequeue_signal(&current->blocked, info);
                spin_unlock_irq(&current->sigmask_lock);

                if (!signr)
                        break;

                if ((current->ptrace & PT_PTRACED) && signr != SIGKILL) {
                        /* Let the debugger run.  */
                        current->exit_code = signr;
                        current->state = TASK_STOPPED;
                        notify_parent(current, SIGCHLD);
                        schedule();

                        /* We're back.  Did the debugger cancel the sig?  */
                        signr = current->exit_code;
                        if (signr == 0)
                                continue;
                        current->exit_code = 0;

                        /* The debugger continued.  Ignore SIGSTOP.  */
                        if (signr == SIGSTOP)
                                continue;

                        /* Update the siginfo structure.  Is this good?  */
                        if (signr != info->si_signo) {
                                info->si_signo = signr;
                                info->si_errno = 0;
                                info->si_code = SI_USER;
                                info->si_pid = current->p_pptr->pid;
                                info->si_uid = current->p_pptr->uid;
                        }

                        /* If the (new) signal is now blocked, requeue it.  */
                        if (sigismember(&current->blocked, signr)) {
                                send_sig_info(signr, info, current);
                                continue;
                        }
                }

                ka = &current->sig->action[signr-1];

                if (ka->sa.sa_handler == SIG_IGN) {
                        if (signr != SIGCHLD)
                                continue;
                        /* Check for SIGCHLD: it's special.  */
                        while (sys_wait4(-1, NULL, WNOHANG, NULL) > 0)
                                /* nothing */;
                        continue;
                }

                if (ka->sa.sa_handler == SIG_DFL) {
                        int exit_code = signr;

                        /* Init gets no signals it doesn't want.  */
                        if (current->pid == 1)
                                continue;

                        switch (signr) {
                        case SIGCONT: case SIGCHLD: case SIGWINCH: case SIGURG:
                                continue;

                        case SIGTSTP: case SIGTTIN: case SIGTTOU:
                                if (is_orphaned_pgrp(current->pgrp))
                                        continue;
                                /* FALLTHRU */

                        case SIGSTOP: {
                                struct signal_struct *sig;
                                current->state = TASK_STOPPED;
                                current->exit_code = signr;
                                sig = current->p_pptr->sig;
                                if (sig && !(sig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
                                        notify_parent(current, SIGCHLD);
                                schedule();
                                continue;
                        }

                        case SIGQUIT: case SIGILL: case SIGTRAP:
                        case SIGABRT: case SIGFPE: case SIGSEGV:
                        case SIGBUS: case SIGSYS: case SIGXCPU: case SIGXFSZ:
                                if (do_coredump(signr, regs))
                                        exit_code |= 0x80;
                                /* FALLTHRU */

                        default:
                                sig_exit(signr, exit_code, info);
                                /* NOTREACHED */
                        }
                }
                return signr;
        }
        return 0;
}

/*
 * Note that 'init' is a special process: it doesn't get signals it doesn't
 * want to handle. Thus you cannot kill init even with a SIGKILL even by
 * mistake.
 */
extern int do_signal32(sigset_t *oldset, struct pt_regs *regs);

int
do_signal(sigset_t *oldset, struct pt_regs *regs)
{
        siginfo_t info;
        int signr;

        /*
         * If the current thread is 32 bit - invoke the
         * 32 bit signal handling code
         */
        if (current->thread.flags & PPC_FLAG_32BIT)
                return do_signal32(oldset, regs);

        if (!oldset)
                oldset = &current->blocked;

        signr = get_signal_to_deliver(&info, regs);
        if (signr > 0) {
                struct k_sigaction *ka = &current->sig->action[signr-1];

                /* Whee!  Actually deliver the signal.  */
                if (regs->trap == 0x0C00)
                        syscall_restart(regs, ka);
                handle_signal(signr, ka, &info, oldset, regs);
                return 1;
        }

        if (regs->trap == 0x0C00 /* System Call! */ &&
            ((int)regs->result == -ERESTARTNOHAND ||
             (int)regs->result == -ERESTARTSYS ||
             (int)regs->result == -ERESTARTNOINTR)) {
                regs->gpr[3] = regs->orig_gpr3;
                regs->nip -= 4;         /* Back up & retry system call */
                regs->result = 0;
        }

        return 0;
}