/*
 * Copyright (C) 2004-2006 Atmel Corporation
 *
 * Based on linux/arch/sh/kernel/signal.c
 *  Copyright (C) 1999, 2000  Niibe Yutaka & Kaz Kojima
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/errno.h>
#include <linux/ptrace.h>
#include <linux/unistd.h>
#include <linux/tracehook.h>

#include <asm/uaccess.h>
#include <asm/ucontext.h>
#include <asm/syscalls.h>

struct rt_sigframe
{
        struct siginfo info;
        struct ucontext uc;
        unsigned long retcode;
};

static int
restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
{
        int err = 0;

#define COPY(x)         err |= __get_user(regs->x, &sc->x)
        COPY(sr);
        COPY(pc);
        COPY(lr);
        COPY(sp);
        COPY(r12);
        COPY(r11);
        COPY(r10);
        COPY(r9);
        COPY(r8);
        COPY(r7);
        COPY(r6);
        COPY(r5);
        COPY(r4);
        COPY(r3);
        COPY(r2);
        COPY(r1);
        COPY(r0);
#undef  COPY

        /*
         * Don't allow anyone to pretend they're running in supervisor
         * mode or something...
         */
        err |= !valid_user_regs(regs);

        return err;
}


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

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

        frame = (struct rt_sigframe __user *)regs->sp;
        pr_debug("SIG return: frame = %p\n", frame);

        if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
                goto badframe;

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

        set_current_blocked(&set);

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

        if (restore_altstack(&frame->uc.uc_stack))
                goto badframe;

        pr_debug("Context restored: pc = %08lx, lr = %08lx, sp = %08lx\n",
                 regs->pc, regs->lr, regs->sp);

        return regs->r12;

badframe:
        force_sig(SIGSEGV, current);
        return 0;
}

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

#define COPY(x)         err |= __put_user(regs->x, &sc->x)
        COPY(sr);
        COPY(pc);
        COPY(lr);
        COPY(sp);
        COPY(r12);
        COPY(r11);
        COPY(r10);
        COPY(r9);
        COPY(r8);
        COPY(r7);
        COPY(r6);
        COPY(r5);
        COPY(r4);
        COPY(r3);
        COPY(r2);
        COPY(r1);
        COPY(r0);
#undef  COPY

        return err;
}

static inline void __user *
get_sigframe(struct ksignal *ksig, struct pt_regs *regs, int framesize)
{
        unsigned long sp = sigsp(regs->sp, ksig);

        return (void __user *)((sp - framesize) & ~3);
}

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

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

        /*
         * Set up the return code:
         *
         *      mov     r8, __NR_rt_sigreturn
         *      scall
         *
         * Note: This will blow up since we're using a non-executable
         * stack. Better use SA_RESTORER.
         */
#if __NR_rt_sigreturn > 127
# error __NR_rt_sigreturn must be < 127 to fit in a short mov
#endif
        err = __put_user(0x3008d733 | (__NR_rt_sigreturn << 20),
                         &frame->retcode);

        err |= copy_siginfo_to_user(&frame->info, &ksig->info);

        /* Set up the ucontext */
        err |= __put_user(0, &frame->uc.uc_flags);
        err |= __put_user(NULL, &frame->uc.uc_link);
        err |= __save_altstack(&frame->uc.uc_stack, regs->sp);
        err |= setup_sigcontext(&frame->uc.uc_mcontext, regs);
        err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));

        if (err)
                goto out;

        regs->r12 = ksig->sig;
        regs->r11 = (unsigned long) &frame->info;
        regs->r10 = (unsigned long) &frame->uc;
        regs->sp = (unsigned long) frame;
        if (ksig->ka.sa.sa_flags & SA_RESTORER)
                regs->lr = (unsigned long)ksig->ka.sa.sa_restorer;
        else {
                printk(KERN_NOTICE "[%s:%d] did not set SA_RESTORER\n",
                       current->comm, current->pid);
                regs->lr = (unsigned long) &frame->retcode;
        }

        pr_debug("SIG deliver [%s:%d]: sig=%d sp=0x%lx pc=0x%lx->0x%p lr=0x%lx\n",
                 current->comm, current->pid, ksig->sig, regs->sp,
                 regs->pc, ksig->ka.sa.sa_handler, regs->lr);

        regs->pc = (unsigned long)ksig->ka.sa.sa_handler;

out:
        return err;
}

static inline void setup_syscall_restart(struct pt_regs *regs)
{
        if (regs->r12 == -ERESTART_RESTARTBLOCK)
                regs->r8 = __NR_restart_syscall;
        else
                regs->r12 = regs->r12_orig;
        regs->pc -= 2;
}

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

        /*
         * Set up the stack frame
         */
        ret = setup_rt_frame(ksig, sigmask_to_save(), regs);

        /*
         * Check that the resulting registers are sane
         */
        ret |= !valid_user_regs(regs);

        /*
         * Block the signal if we were successful.
         */
        signal_setup_done(ret, ksig, 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.
 */
static void do_signal(struct pt_regs *regs, int syscall)
{
        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;

        get_signal(&ksig);
        if (syscall) {
                switch (regs->r12) {
                case -ERESTART_RESTARTBLOCK:
                case -ERESTARTNOHAND:
                        if (ksig.sig > 0) {
                                regs->r12 = -EINTR;
                                break;
                        }
                        /* fall through */
                case -ERESTARTSYS:
                        if (ksig.sig > 0 && !(ksig.ka.sa.sa_flags & SA_RESTART)) {
                                regs->r12 = -EINTR;
                                break;
                        }
                        /* fall through */
                case -ERESTARTNOINTR:
                        setup_syscall_restart(regs);
                }
        }

        if (!ksig.sig) {
                /* No signal to deliver -- put the saved sigmask back */
                restore_saved_sigmask();
                return;
        }

        handle_signal(&ksig, regs, syscall);
}

asmlinkage void do_notify_resume(struct pt_regs *regs, struct thread_info *ti)
{
        int syscall = 0;

        if ((sysreg_read(SR) & MODE_MASK) == MODE_SUPERVISOR)
                syscall = 1;

        if (ti->flags & _TIF_SIGPENDING)
                do_signal(regs, syscall);

        if (ti->flags & _TIF_NOTIFY_RESUME) {
                clear_thread_flag(TIF_NOTIFY_RESUME);
                tracehook_notify_resume(regs);
        }
}