/*
 * linux/arch/unicore32/kernel/signal.c
 *
 * Code specific to PKUnity SoC and UniCore ISA
 *
 * Copyright (C) 2001-2010 GUAN Xue-tao
 *
 * 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/errno.h>
#include <linux/signal.h>
#include <linux/personality.h>
#include <linux/freezer.h>
#include <linux/uaccess.h>
#include <linux/tracehook.h>
#include <linux/elf.h>
#include <linux/unistd.h>

#include <asm/cacheflush.h>
#include <asm/ucontext.h>

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

/*
 * For UniCore syscalls, we encode the syscall number into the instruction.
 */
#define SWI_SYS_SIGRETURN       (0xff000000) /* error number for new abi */
#define SWI_SYS_RT_SIGRETURN    (0xff000000 | (__NR_rt_sigreturn))
#define SWI_SYS_RESTART         (0xff000000 | (__NR_restart_syscall))

#define KERN_SIGRETURN_CODE     (KUSER_VECPAGE_BASE + 0x00000500)
#define KERN_RESTART_CODE       (KERN_SIGRETURN_CODE + sizeof(sigreturn_codes))

const unsigned long sigreturn_codes[3] = {
        SWI_SYS_SIGRETURN, SWI_SYS_RT_SIGRETURN,
};

const unsigned long syscall_restart_code[2] = {
        SWI_SYS_RESTART,        /* swi  __NR_restart_syscall */
        0x69efc004,             /* ldr  pc, [sp], #4 */
};

/*
 * Do a signal return; undo the signal stack.  These are aligned to 64-bit.
 */
struct sigframe {
        struct ucontext uc;
        unsigned long retcode[2];
};

struct rt_sigframe {
        struct siginfo info;
        struct sigframe sig;
};

static int restore_sigframe(struct pt_regs *regs, struct sigframe __user *sf)
{
        sigset_t set;
        int err;

        err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set));
        if (err == 0) {
                sigdelsetmask(&set, ~_BLOCKABLE);
                set_current_blocked(&set);
        }

        err |= __get_user(regs->UCreg_00, &sf->uc.uc_mcontext.regs.UCreg_00);
        err |= __get_user(regs->UCreg_01, &sf->uc.uc_mcontext.regs.UCreg_01);
        err |= __get_user(regs->UCreg_02, &sf->uc.uc_mcontext.regs.UCreg_02);
        err |= __get_user(regs->UCreg_03, &sf->uc.uc_mcontext.regs.UCreg_03);
        err |= __get_user(regs->UCreg_04, &sf->uc.uc_mcontext.regs.UCreg_04);
        err |= __get_user(regs->UCreg_05, &sf->uc.uc_mcontext.regs.UCreg_05);
        err |= __get_user(regs->UCreg_06, &sf->uc.uc_mcontext.regs.UCreg_06);
        err |= __get_user(regs->UCreg_07, &sf->uc.uc_mcontext.regs.UCreg_07);
        err |= __get_user(regs->UCreg_08, &sf->uc.uc_mcontext.regs.UCreg_08);
        err |= __get_user(regs->UCreg_09, &sf->uc.uc_mcontext.regs.UCreg_09);
        err |= __get_user(regs->UCreg_10, &sf->uc.uc_mcontext.regs.UCreg_10);
        err |= __get_user(regs->UCreg_11, &sf->uc.uc_mcontext.regs.UCreg_11);
        err |= __get_user(regs->UCreg_12, &sf->uc.uc_mcontext.regs.UCreg_12);
        err |= __get_user(regs->UCreg_13, &sf->uc.uc_mcontext.regs.UCreg_13);
        err |= __get_user(regs->UCreg_14, &sf->uc.uc_mcontext.regs.UCreg_14);
        err |= __get_user(regs->UCreg_15, &sf->uc.uc_mcontext.regs.UCreg_15);
        err |= __get_user(regs->UCreg_16, &sf->uc.uc_mcontext.regs.UCreg_16);
        err |= __get_user(regs->UCreg_17, &sf->uc.uc_mcontext.regs.UCreg_17);
        err |= __get_user(regs->UCreg_18, &sf->uc.uc_mcontext.regs.UCreg_18);
        err |= __get_user(regs->UCreg_19, &sf->uc.uc_mcontext.regs.UCreg_19);
        err |= __get_user(regs->UCreg_20, &sf->uc.uc_mcontext.regs.UCreg_20);
        err |= __get_user(regs->UCreg_21, &sf->uc.uc_mcontext.regs.UCreg_21);
        err |= __get_user(regs->UCreg_22, &sf->uc.uc_mcontext.regs.UCreg_22);
        err |= __get_user(regs->UCreg_23, &sf->uc.uc_mcontext.regs.UCreg_23);
        err |= __get_user(regs->UCreg_24, &sf->uc.uc_mcontext.regs.UCreg_24);
        err |= __get_user(regs->UCreg_25, &sf->uc.uc_mcontext.regs.UCreg_25);
        err |= __get_user(regs->UCreg_26, &sf->uc.uc_mcontext.regs.UCreg_26);
        err |= __get_user(regs->UCreg_fp, &sf->uc.uc_mcontext.regs.UCreg_fp);
        err |= __get_user(regs->UCreg_ip, &sf->uc.uc_mcontext.regs.UCreg_ip);
        err |= __get_user(regs->UCreg_sp, &sf->uc.uc_mcontext.regs.UCreg_sp);
        err |= __get_user(regs->UCreg_lr, &sf->uc.uc_mcontext.regs.UCreg_lr);
        err |= __get_user(regs->UCreg_pc, &sf->uc.uc_mcontext.regs.UCreg_pc);
        err |= __get_user(regs->UCreg_asr, &sf->uc.uc_mcontext.regs.UCreg_asr);

        err |= !valid_user_regs(regs);

        return err;
}

asmlinkage int __sys_rt_sigreturn(struct pt_regs *regs)
{
        struct rt_sigframe __user *frame;

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

        /*
         * Since we stacked the signal on a 64-bit boundary,
         * then 'sp' should be word aligned here.  If it's
         * not, then the user is trying to mess with us.
         */
        if (regs->UCreg_sp & 7)
                goto badframe;

        frame = (struct rt_sigframe __user *)regs->UCreg_sp;

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

        if (restore_sigframe(regs, &frame->sig))
                goto badframe;

        if (do_sigaltstack(&frame->sig.uc.uc_stack, NULL, regs->UCreg_sp)
                        == -EFAULT)
                goto badframe;

        return regs->UCreg_00;

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

static int setup_sigframe(struct sigframe __user *sf, struct pt_regs *regs,
                sigset_t *set)
{
        int err = 0;

        err |= __put_user(regs->UCreg_00, &sf->uc.uc_mcontext.regs.UCreg_00);
        err |= __put_user(regs->UCreg_01, &sf->uc.uc_mcontext.regs.UCreg_01);
        err |= __put_user(regs->UCreg_02, &sf->uc.uc_mcontext.regs.UCreg_02);
        err |= __put_user(regs->UCreg_03, &sf->uc.uc_mcontext.regs.UCreg_03);
        err |= __put_user(regs->UCreg_04, &sf->uc.uc_mcontext.regs.UCreg_04);
        err |= __put_user(regs->UCreg_05, &sf->uc.uc_mcontext.regs.UCreg_05);
        err |= __put_user(regs->UCreg_06, &sf->uc.uc_mcontext.regs.UCreg_06);
        err |= __put_user(regs->UCreg_07, &sf->uc.uc_mcontext.regs.UCreg_07);
        err |= __put_user(regs->UCreg_08, &sf->uc.uc_mcontext.regs.UCreg_08);
        err |= __put_user(regs->UCreg_09, &sf->uc.uc_mcontext.regs.UCreg_09);
        err |= __put_user(regs->UCreg_10, &sf->uc.uc_mcontext.regs.UCreg_10);
        err |= __put_user(regs->UCreg_11, &sf->uc.uc_mcontext.regs.UCreg_11);
        err |= __put_user(regs->UCreg_12, &sf->uc.uc_mcontext.regs.UCreg_12);
        err |= __put_user(regs->UCreg_13, &sf->uc.uc_mcontext.regs.UCreg_13);
        err |= __put_user(regs->UCreg_14, &sf->uc.uc_mcontext.regs.UCreg_14);
        err |= __put_user(regs->UCreg_15, &sf->uc.uc_mcontext.regs.UCreg_15);
        err |= __put_user(regs->UCreg_16, &sf->uc.uc_mcontext.regs.UCreg_16);
        err |= __put_user(regs->UCreg_17, &sf->uc.uc_mcontext.regs.UCreg_17);
        err |= __put_user(regs->UCreg_18, &sf->uc.uc_mcontext.regs.UCreg_18);
        err |= __put_user(regs->UCreg_19, &sf->uc.uc_mcontext.regs.UCreg_19);
        err |= __put_user(regs->UCreg_20, &sf->uc.uc_mcontext.regs.UCreg_20);
        err |= __put_user(regs->UCreg_21, &sf->uc.uc_mcontext.regs.UCreg_21);
        err |= __put_user(regs->UCreg_22, &sf->uc.uc_mcontext.regs.UCreg_22);
        err |= __put_user(regs->UCreg_23, &sf->uc.uc_mcontext.regs.UCreg_23);
        err |= __put_user(regs->UCreg_24, &sf->uc.uc_mcontext.regs.UCreg_24);
        err |= __put_user(regs->UCreg_25, &sf->uc.uc_mcontext.regs.UCreg_25);
        err |= __put_user(regs->UCreg_26, &sf->uc.uc_mcontext.regs.UCreg_26);
        err |= __put_user(regs->UCreg_fp, &sf->uc.uc_mcontext.regs.UCreg_fp);
        err |= __put_user(regs->UCreg_ip, &sf->uc.uc_mcontext.regs.UCreg_ip);
        err |= __put_user(regs->UCreg_sp, &sf->uc.uc_mcontext.regs.UCreg_sp);
        err |= __put_user(regs->UCreg_lr, &sf->uc.uc_mcontext.regs.UCreg_lr);
        err |= __put_user(regs->UCreg_pc, &sf->uc.uc_mcontext.regs.UCreg_pc);
        err |= __put_user(regs->UCreg_asr, &sf->uc.uc_mcontext.regs.UCreg_asr);

        err |= __put_user(current->thread.trap_no,
                        &sf->uc.uc_mcontext.trap_no);
        err |= __put_user(current->thread.error_code,
                        &sf->uc.uc_mcontext.error_code);
        err |= __put_user(current->thread.address,
                        &sf->uc.uc_mcontext.fault_address);
        err |= __put_user(set->sig[0], &sf->uc.uc_mcontext.oldmask);

        err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(*set));

        return err;
}

static inline void __user *get_sigframe(struct k_sigaction *ka,
                struct pt_regs *regs, int framesize)
{
        unsigned long sp = regs->UCreg_sp;
        void __user *frame;

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

        /*
         * ATPCS B01 mandates 8-byte alignment
         */
        frame = (void __user *)((sp - framesize) & ~7);

        /*
         * Check that we can actually write to the signal frame.
         */
        if (!access_ok(VERIFY_WRITE, frame, framesize))
                frame = NULL;

        return frame;
}

static int setup_return(struct pt_regs *regs, struct k_sigaction *ka,
             unsigned long __user *rc, void __user *frame, int usig)
{
        unsigned long handler = (unsigned long)ka->sa.sa_handler;
        unsigned long retcode;
        unsigned long asr = regs->UCreg_asr & ~PSR_f;

        unsigned int idx = 0;

        if (ka->sa.sa_flags & SA_SIGINFO)
                idx += 1;

        if (__put_user(sigreturn_codes[idx],   rc) ||
            __put_user(sigreturn_codes[idx+1], rc+1))
                return 1;

        retcode = KERN_SIGRETURN_CODE + (idx << 2);

        regs->UCreg_00 = usig;
        regs->UCreg_sp = (unsigned long)frame;
        regs->UCreg_lr = retcode;
        regs->UCreg_pc = handler;
        regs->UCreg_asr = asr;

        return 0;
}

static int setup_frame(int usig, struct k_sigaction *ka,
                sigset_t *set, struct pt_regs *regs)
{
        struct sigframe __user *frame = get_sigframe(ka, regs, sizeof(*frame));
        int err = 0;

        if (!frame)
                return 1;

        /*
         * Set uc.uc_flags to a value which sc.trap_no would never have.
         */
        err |= __put_user(0x5ac3c35a, &frame->uc.uc_flags);

        err |= setup_sigframe(frame, regs, set);
        if (err == 0)
                err |= setup_return(regs, ka, frame->retcode, frame, usig);

        return err;
}

static int setup_rt_frame(int usig, struct k_sigaction *ka, siginfo_t *info,
               sigset_t *set, struct pt_regs *regs)
{
        struct rt_sigframe __user *frame =
                        get_sigframe(ka, regs, sizeof(*frame));
        stack_t stack;
        int err = 0;

        if (!frame)
                return 1;

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

        err |= __put_user(0, &frame->sig.uc.uc_flags);
        err |= __put_user(NULL, &frame->sig.uc.uc_link);

        memset(&stack, 0, sizeof(stack));
        stack.ss_sp = (void __user *)current->sas_ss_sp;
        stack.ss_flags = sas_ss_flags(regs->UCreg_sp);
        stack.ss_size = current->sas_ss_size;
        err |= __copy_to_user(&frame->sig.uc.uc_stack, &stack, sizeof(stack));

        err |= setup_sigframe(&frame->sig, regs, set);
        if (err == 0)
                err |= setup_return(regs, ka, frame->sig.retcode, frame, usig);

        if (err == 0) {
                /*
                 * For realtime signals we must also set the second and third
                 * arguments for the signal handler.
                 */
                regs->UCreg_01 = (unsigned long)&frame->info;
                regs->UCreg_02 = (unsigned long)&frame->sig.uc;
        }

        return err;
}

static inline void setup_syscall_restart(struct pt_regs *regs)
{
        regs->UCreg_00 = regs->UCreg_ORIG_00;
        regs->UCreg_pc -= 4;
}

/*
 * OK, we're invoking a handler
 */
static int handle_signal(unsigned long sig, struct k_sigaction *ka,
              siginfo_t *info, sigset_t *oldset,
              struct pt_regs *regs, int syscall)
{
        struct thread_info *thread = current_thread_info();
        struct task_struct *tsk = current;
        sigset_t blocked;
        int usig = sig;
        int ret;

        /*
         * If we were from a system call, check for system call restarting...
         */
        if (syscall) {
                switch (regs->UCreg_00) {
                case -ERESTART_RESTARTBLOCK:
                case -ERESTARTNOHAND:
                        regs->UCreg_00 = -EINTR;
                        break;
                case -ERESTARTSYS:
                        if (!(ka->sa.sa_flags & SA_RESTART)) {
                                regs->UCreg_00 = -EINTR;
                                break;
                        }
                        /* fallthrough */
                case -ERESTARTNOINTR:
                        setup_syscall_restart(regs);
                }
        }

        /*
         * translate the signal
         */
        if (usig < 32 && thread->exec_domain
                        && thread->exec_domain->signal_invmap)
                usig = thread->exec_domain->signal_invmap[usig];

        /*
         * Set up the stack frame
         */
        if (ka->sa.sa_flags & SA_SIGINFO)
                ret = setup_rt_frame(usig, ka, info, oldset, regs);
        else
                ret = setup_frame(usig, ka, oldset, regs);

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

        if (ret != 0) {
                force_sigsegv(sig, tsk);
                return ret;
        }

        /*
         * Block the signal if we were successful.
         */
        sigorsets(&blocked, &tsk->blocked, &ka->sa.sa_mask);
        if (!(ka->sa.sa_flags & SA_NODEFER))
                sigaddset(&blocked, sig);
        set_current_blocked(&blocked);

        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.
 *
 * Note that we go through the signals twice: once to check the signals that
 * the kernel can handle, and then we build all the user-level signal handling
 * stack-frames in one go after that.
 */
static void do_signal(struct pt_regs *regs, int syscall)
{
        struct k_sigaction ka;
        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 (try_to_freeze())
                goto no_signal;

        signr = get_signal_to_deliver(&info, &ka, regs, NULL);
        if (signr > 0) {
                sigset_t *oldset;

                if (test_thread_flag(TIF_RESTORE_SIGMASK))
                        oldset = &current->saved_sigmask;
                else
                        oldset = &current->blocked;
                if (handle_signal(signr, &ka, &info, oldset, regs, syscall)
                                == 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;
        }

 no_signal:
        /*
         * No signal to deliver to the process - restart the syscall.
         */
        if (syscall) {
                if (regs->UCreg_00 == -ERESTART_RESTARTBLOCK) {
                                u32 __user *usp;

                                regs->UCreg_sp -= 4;
                                usp = (u32 __user *)regs->UCreg_sp;

                                if (put_user(regs->UCreg_pc, usp) == 0) {
                                        regs->UCreg_pc = KERN_RESTART_CODE;
                                } else {
                                        regs->UCreg_sp += 4;
                                        force_sigsegv(0, current);
                                }
                }
                if (regs->UCreg_00 == -ERESTARTNOHAND ||
                    regs->UCreg_00 == -ERESTARTSYS ||
                    regs->UCreg_00 == -ERESTARTNOINTR) {
                        setup_syscall_restart(regs);
                }

                /* 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);
                }
        }
}

asmlinkage void do_notify_resume(struct pt_regs *regs,
                unsigned int thread_flags, int syscall)
{
        if (thread_flags & _TIF_SIGPENDING)
                do_signal(regs, syscall);

        if (thread_flags & _TIF_NOTIFY_RESUME) {
                clear_thread_flag(TIF_NOTIFY_RESUME);
                tracehook_notify_resume(regs);
                if (current->replacement_session_keyring)
                        key_replace_session_keyring();
        }
}

/*
 * Copy signal return handlers into the vector page, and
 * set sigreturn to be a pointer to these.
 */
void __init early_signal_init(void)
{
        memcpy((void *)kuser_vecpage_to_vectors(KERN_SIGRETURN_CODE),
                        sigreturn_codes, sizeof(sigreturn_codes));
        memcpy((void *)kuser_vecpage_to_vectors(KERN_RESTART_CODE),
                        syscall_restart_code, sizeof(syscall_restart_code));
        /* Need not to flush icache, since early_trap_init will do it last. */
}