/*
 * Copyright 2010 Tilera Corporation. All Rights Reserved.
 *
 *   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, version 2.
 *
 *   This program is distributed in the hope that it will be useful, but
 *   WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
 *   NON INFRINGEMENT.  See the GNU General Public License for
 *   more details.
 */

#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/kernel.h>
#include <linux/signal.h>
#include <linux/errno.h>
#include <linux/wait.h>
#include <linux/unistd.h>
#include <linux/stddef.h>
#include <linux/personality.h>
#include <linux/suspend.h>
#include <linux/ptrace.h>
#include <linux/elf.h>
#include <linux/compat.h>
#include <linux/syscalls.h>
#include <linux/uaccess.h>
#include <asm/processor.h>
#include <asm/ucontext.h>
#include <asm/sigframe.h>
#include <asm/syscalls.h>
#include <asm/vdso.h>
#include <arch/interrupts.h>

struct compat_ucontext {
        compat_ulong_t    uc_flags;
        compat_uptr_t     uc_link;
        struct compat_sigaltstack         uc_stack;
        struct sigcontext uc_mcontext;
        sigset_t          uc_sigmask;   /* mask last for extensibility */
};

struct compat_rt_sigframe {
        unsigned char save_area[C_ABI_SAVE_AREA_SIZE]; /* caller save area */
        struct compat_siginfo info;
        struct compat_ucontext uc;
};

int copy_siginfo_to_user32(struct compat_siginfo __user *to, const siginfo_t *from)
{
        int err;

        if (!access_ok(VERIFY_WRITE, to, sizeof(struct compat_siginfo)))
                return -EFAULT;

        /* If you change siginfo_t structure, please make sure that
           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);

        if (from->si_code < 0) {
                err |= __put_user(from->si_pid, &to->si_pid);
                err |= __put_user(from->si_uid, &to->si_uid);
                err |= __put_user(ptr_to_compat(from->si_ptr), &to->si_ptr);
        } else {
                /*
                 * First 32bits of unions are always present:
                 * si_pid === si_band === si_tid === si_addr(LS half)
                 */
                err |= __put_user(from->_sifields._pad[0],
                                  &to->_sifields._pad[0]);
                switch (from->si_code >> 16) {
                case __SI_FAULT >> 16:
                        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);
                        /* FALL THROUGH */
                default:
                case __SI_KILL >> 16:
                        err |= __put_user(from->si_uid, &to->si_uid);
                        break;
                case __SI_POLL >> 16:
                        err |= __put_user(from->si_fd, &to->si_fd);
                        break;
                case __SI_TIMER >> 16:
                        err |= __put_user(from->si_overrun, &to->si_overrun);
                        err |= __put_user(ptr_to_compat(from->si_ptr),
                                          &to->si_ptr);
                        break;
                         /* This is not generated by the kernel as of now.  */
                case __SI_RT >> 16:
                case __SI_MESGQ >> 16:
                        err |= __put_user(from->si_uid, &to->si_uid);
                        err |= __put_user(from->si_int, &to->si_int);
                        break;
                }
        }
        return err;
}

int copy_siginfo_from_user32(siginfo_t *to, struct compat_siginfo __user *from)
{
        int err;
        u32 ptr32;

        if (!access_ok(VERIFY_READ, from, sizeof(struct compat_siginfo)))
                return -EFAULT;

        err = __get_user(to->si_signo, &from->si_signo);
        err |= __get_user(to->si_errno, &from->si_errno);
        err |= __get_user(to->si_code, &from->si_code);

        err |= __get_user(to->si_pid, &from->si_pid);
        err |= __get_user(to->si_uid, &from->si_uid);
        err |= __get_user(ptr32, &from->si_ptr);
        to->si_ptr = compat_ptr(ptr32);

        return err;
}

/* The assembly shim for this function arranges to ignore the return value. */
long compat_sys_rt_sigreturn(void)
{
        struct pt_regs *regs = current_pt_regs();
        struct compat_rt_sigframe __user *frame =
                (struct compat_rt_sigframe __user *) compat_ptr(regs->sp);
        sigset_t set;

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

        return 0;

badframe:
        signal_fault("bad sigreturn frame", regs, frame, 0);
        return 0;
}

/*
 * Determine which stack to use..
 */
static inline void __user *compat_get_sigframe(struct k_sigaction *ka,
                                               struct pt_regs *regs,
                                               size_t frame_size)
{
        unsigned long sp;

        /* Default to using normal stack */
        sp = (unsigned long)compat_ptr(regs->sp);

        /*
         * If we are on the alternate signal stack and would overflow
         * it, don't.  Return an always-bogus address instead so we
         * will die with SIGSEGV.
         */
        if (on_sig_stack(sp) && !likely(on_sig_stack(sp - frame_size)))
                return (void __user __force *)-1UL;

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

        sp -= frame_size;
        /*
         * Align the stack pointer according to the TILE ABI,
         * i.e. so that on function entry (sp & 15) == 0.
         */
        sp &= -16UL;
        return (void __user *) sp;
}

int compat_setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
                          sigset_t *set, struct pt_regs *regs)
{
        unsigned long restorer;
        struct compat_rt_sigframe __user *frame;
        int err = 0;
        int usig;

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

        if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
                goto give_sigsegv;

        usig = current_thread_info()->exec_domain
                && current_thread_info()->exec_domain->signal_invmap
                && sig < 32
                ? current_thread_info()->exec_domain->signal_invmap[sig]
                : sig;

        /* Always write at least the signal number for the stack backtracer. */
        if (ka->sa.sa_flags & SA_SIGINFO) {
                /* At sigreturn time, restore the callee-save registers too. */
                err |= copy_siginfo_to_user32(&frame->info, info);
                regs->flags |= PT_FLAGS_RESTORE_REGS;
        } else {
                err |= __put_user(info->si_signo, &frame->info.si_signo);
        }

        /* Create the ucontext.  */
        err |= __clear_user(&frame->save_area, sizeof(frame->save_area));
        err |= __put_user(0, &frame->uc.uc_flags);
        err |= __put_user(0, &frame->uc.uc_link);
        err |= __compat_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 give_sigsegv;

        restorer = VDSO_SYM(&__vdso_rt_sigreturn);
        if (ka->sa.sa_flags & SA_RESTORER)
                restorer = ptr_to_compat_reg(ka->sa.sa_restorer);

        /*
         * Set up registers for signal handler.
         * Registers that we don't modify keep the value they had from
         * user-space at the time we took the signal.
         * We always pass siginfo and mcontext, regardless of SA_SIGINFO,
         * since some things rely on this (e.g. glibc's debug/segfault.c).
         */
        regs->pc = ptr_to_compat_reg(ka->sa.sa_handler);
        regs->ex1 = PL_ICS_EX1(USER_PL, 1); /* set crit sec in handler */
        regs->sp = ptr_to_compat_reg(frame);
        regs->lr = restorer;
        regs->regs[0] = (unsigned long) usig;
        regs->regs[1] = ptr_to_compat_reg(&frame->info);
        regs->regs[2] = ptr_to_compat_reg(&frame->uc);
        regs->flags |= PT_FLAGS_CALLER_SAVES;
        return 0;

give_sigsegv:
        signal_fault("bad setup frame", regs, frame, sig);
        return -EFAULT;
}