/*
 * Ptrace support for Hexagon
 *
 * Copyright (c) 2010-2013, The Linux Foundation. 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 version 2 and
 * only version 2 as published by the Free Software Foundation.
 *
 * 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.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301, USA.
 */

#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/sched/task_stack.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/errno.h>
#include <linux/ptrace.h>
#include <linux/regset.h>
#include <linux/user.h>
#include <linux/elf.h>

#include <asm/user.h>

#if arch_has_single_step()
/*  Both called from ptrace_resume  */
void user_enable_single_step(struct task_struct *child)
{
        pt_set_singlestep(task_pt_regs(child));
        set_tsk_thread_flag(child, TIF_SINGLESTEP);
}

void user_disable_single_step(struct task_struct *child)
{
        pt_clr_singlestep(task_pt_regs(child));
        clear_tsk_thread_flag(child, TIF_SINGLESTEP);
}
#endif

static int genregs_get(struct task_struct *target,
                   const struct user_regset *regset,
                   unsigned int pos, unsigned int count,
                   void *kbuf, void __user *ubuf)
{
        int ret;
        unsigned int dummy;
        struct pt_regs *regs = task_pt_regs(target);


        if (!regs)
                return -EIO;

        /* The general idea here is that the copyout must happen in
         * exactly the same order in which the userspace expects these
         * regs. Now, the sequence in userspace does not match the
         * sequence in the kernel, so everything past the 32 gprs
         * happens one at a time.
         */
        ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
                                  &regs->r00, 0, 32*sizeof(unsigned long));

#define ONEXT(KPT_REG, USR_REG) \
        if (!ret) \
                ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf, \
                        KPT_REG, offsetof(struct user_regs_struct, USR_REG), \
                        offsetof(struct user_regs_struct, USR_REG) + \
                                 sizeof(unsigned long));

        /* Must be exactly same sequence as struct user_regs_struct */
        ONEXT(&regs->sa0, sa0);
        ONEXT(&regs->lc0, lc0);
        ONEXT(&regs->sa1, sa1);
        ONEXT(&regs->lc1, lc1);
        ONEXT(&regs->m0, m0);
        ONEXT(&regs->m1, m1);
        ONEXT(&regs->usr, usr);
        ONEXT(&regs->preds, p3_0);
        ONEXT(&regs->gp, gp);
        ONEXT(&regs->ugp, ugp);
        ONEXT(&pt_elr(regs), pc);
        dummy = pt_cause(regs);
        ONEXT(&dummy, cause);
        ONEXT(&pt_badva(regs), badva);
#if CONFIG_HEXAGON_ARCH_VERSION >=4
        ONEXT(&regs->cs0, cs0);
        ONEXT(&regs->cs1, cs1);
#endif

        /* Pad the rest with zeros, if needed */
        if (!ret)
                ret = user_regset_copyout_zero(&pos, &count, &kbuf, &ubuf,
                                        offsetof(struct user_regs_struct, pad1), -1);
        return ret;
}

static int genregs_set(struct task_struct *target,
                   const struct user_regset *regset,
                   unsigned int pos, unsigned int count,
                   const void *kbuf, const void __user *ubuf)
{
        int ret;
        unsigned long bucket;
        struct pt_regs *regs = task_pt_regs(target);

        if (!regs)
                return -EIO;

        ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
                                 &regs->r00, 0, 32*sizeof(unsigned long));

#define INEXT(KPT_REG, USR_REG) \
        if (!ret) \
                ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, \
                        KPT_REG, offsetof(struct user_regs_struct, USR_REG), \
                        offsetof(struct user_regs_struct, USR_REG) + \
                                sizeof(unsigned long));

        /* Must be exactly same sequence as struct user_regs_struct */
        INEXT(&regs->sa0, sa0);
        INEXT(&regs->lc0, lc0);
        INEXT(&regs->sa1, sa1);
        INEXT(&regs->lc1, lc1);
        INEXT(&regs->m0, m0);
        INEXT(&regs->m1, m1);
        INEXT(&regs->usr, usr);
        INEXT(&regs->preds, p3_0);
        INEXT(&regs->gp, gp);
        INEXT(&regs->ugp, ugp);
        INEXT(&pt_elr(regs), pc);

        /* CAUSE and BADVA aren't writeable. */
        INEXT(&bucket, cause);
        INEXT(&bucket, badva);

#if CONFIG_HEXAGON_ARCH_VERSION >=4
        INEXT(&regs->cs0, cs0);
        INEXT(&regs->cs1, cs1);
#endif

        /* Ignore the rest, if needed */
        if (!ret)
                ret = user_regset_copyin_ignore(&pos, &count, &kbuf, &ubuf,
                                        offsetof(struct user_regs_struct, pad1), -1);

        if (ret)
                return ret;

        /*
         * This is special; SP is actually restored by the VM via the
         * special event record which is set by the special trap.
         */
        regs->hvmer.vmpsp = regs->r29;
        return 0;
}

enum hexagon_regset {
        REGSET_GENERAL,
};

static const struct user_regset hexagon_regsets[] = {
        [REGSET_GENERAL] = {
                .core_note_type = NT_PRSTATUS,
                .n = ELF_NGREG,
                .size = sizeof(unsigned long),
                .align = sizeof(unsigned long),
                .get = genregs_get,
                .set = genregs_set,
        },
};

static const struct user_regset_view hexagon_user_view = {
        .name = "hexagon",
        .e_machine = ELF_ARCH,
        .ei_osabi = ELF_OSABI,
        .regsets = hexagon_regsets,
        .e_flags = ELF_CORE_EFLAGS,
        .n = ARRAY_SIZE(hexagon_regsets)
};

const struct user_regset_view *task_user_regset_view(struct task_struct *task)
{
        return &hexagon_user_view;
}

void ptrace_disable(struct task_struct *child)
{
        /* Boilerplate - resolves to null inline if no HW single-step */
        user_disable_single_step(child);
}

long arch_ptrace(struct task_struct *child, long request,
                 unsigned long addr, unsigned long data)
{
        return ptrace_request(child, request, addr, data);
}