/*
 * arch/score/kernel/ptrace.c
 *
 * Score Processor version.
 *
 * Copyright (C) 2009 Sunplus Core Technology Co., Ltd.
 *  Chen Liqin <liqin.chen@sunplusct.com>
 *  Lennox Wu <lennox.wu@sunplusct.com>
 *
 * 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.
 *
 * 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, see the file COPYING, or write
 * to the Free Software Foundation, Inc.,
 * 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */

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

#include <linux/uaccess.h>

/*
 * retrieve the contents of SCORE userspace general registers
 */
static int genregs_get(struct task_struct *target,
		       const struct user_regset *regset,
		       unsigned int pos, unsigned int count,
		       void *kbuf, void __user *ubuf)
{
	const struct pt_regs *regs = task_pt_regs(target);
	int ret;

	/* skip 9 * sizeof(unsigned long) not use for pt_regs */
	ret = user_regset_copyout_zero(&pos, &count, &kbuf, &ubuf,
					0, offsetof(struct pt_regs, regs));

	/* r0 - r31, cel, ceh, sr0, sr1, sr2, epc, ema, psr, ecr, condition */
	ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
				  regs->regs,
				  offsetof(struct pt_regs, regs),
				  offsetof(struct pt_regs, cp0_condition));

	if (!ret)
		ret = user_regset_copyout_zero(&pos, &count, &kbuf, &ubuf,
						sizeof(struct pt_regs), -1);

	return ret;
}

/*
 * update the contents of the SCORE userspace general registers
 */
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)
{
	struct pt_regs *regs = task_pt_regs(target);
	int ret;

	/* skip 9 * sizeof(unsigned long) */
	ret = user_regset_copyin_ignore(&pos, &count, &kbuf, &ubuf,
					0, offsetof(struct pt_regs, regs));

	/* r0 - r31, cel, ceh, sr0, sr1, sr2, epc, ema, psr, ecr, condition */
	ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
				  regs->regs,
				  offsetof(struct pt_regs, regs),
				  offsetof(struct pt_regs, cp0_condition));

	if (!ret)
		ret = user_regset_copyin_ignore(&pos, &count, &kbuf, &ubuf,
						sizeof(struct pt_regs), -1);

	return ret;
}

/*
 * Define the register sets available on the score7 under Linux
 */
enum score7_regset {
	REGSET_GENERAL,
};

static const struct user_regset score7_regsets[] = {
	[REGSET_GENERAL] = {
		.core_note_type	= NT_PRSTATUS,
		.n		= ELF_NGREG,
		.size		= sizeof(long),
		.align		= sizeof(long),
		.get		= genregs_get,
		.set		= genregs_set,
	},
};

static const struct user_regset_view user_score_native_view = {
	.name		= "score7",
	.e_machine	= EM_SCORE7,
	.regsets	= score7_regsets,
	.n		= ARRAY_SIZE(score7_regsets),
};

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

static int is_16bitinsn(unsigned long insn)
{
	if ((insn & INSN32_MASK) == INSN32_MASK)
		return 0;
	else
		return 1;
}

int
read_tsk_long(struct task_struct *child,
		unsigned long addr, unsigned long *res)
{
	int copied;

	copied = access_process_vm(child, addr, res, sizeof(*res), FOLL_FORCE);

	return copied != sizeof(*res) ? -EIO : 0;
}

int
read_tsk_short(struct task_struct *child,
		unsigned long addr, unsigned short *res)
{
	int copied;

	copied = access_process_vm(child, addr, res, sizeof(*res), FOLL_FORCE);

	return copied != sizeof(*res) ? -EIO : 0;
}

static int
write_tsk_short(struct task_struct *child,
		unsigned long addr, unsigned short val)
{
	int copied;

	copied = access_process_vm(child, addr, &val, sizeof(val),
			FOLL_FORCE | FOLL_WRITE);

	return copied != sizeof(val) ? -EIO : 0;
}

static int
write_tsk_long(struct task_struct *child,
		unsigned long addr, unsigned long val)
{
	int copied;

	copied = access_process_vm(child, addr, &val, sizeof(val),
			FOLL_FORCE | FOLL_WRITE);

	return copied != sizeof(val) ? -EIO : 0;
}

void user_enable_single_step(struct task_struct *child)
{
	/* far_epc is the target of branch */
	unsigned int epc, far_epc = 0;
	unsigned long epc_insn, far_epc_insn;
	int ninsn_type;			/* next insn type 0=16b, 1=32b */
	unsigned int tmp, tmp2;
	struct pt_regs *regs = task_pt_regs(child);
	child->thread.single_step = 1;
	child->thread.ss_nextcnt = 1;
	epc = regs->cp0_epc;

	read_tsk_long(child, epc, &epc_insn);

	if (is_16bitinsn(epc_insn)) {
		if ((epc_insn & J16M) == J16) {
			tmp = epc_insn & 0xFFE;
			epc = (epc & 0xFFFFF000) | tmp;
		} else if ((epc_insn & B16M) == B16) {
			child->thread.ss_nextcnt = 2;
			tmp = (epc_insn & 0xFF) << 1;
			tmp = tmp << 23;
			tmp = (unsigned int)((int) tmp >> 23);
			far_epc = epc + tmp;
			epc += 2;
		} else if ((epc_insn & BR16M) == BR16) {
			child->thread.ss_nextcnt = 2;
			tmp = (epc_insn >> 4) & 0xF;
			far_epc = regs->regs[tmp];
			epc += 2;
		} else
			epc += 2;
	} else {
		if ((epc_insn & J32M) == J32) {
			tmp = epc_insn & 0x03FFFFFE;
			tmp2 = tmp & 0x7FFF;
			tmp = (((tmp >> 16) & 0x3FF) << 15) | tmp2;
			epc = (epc & 0xFFC00000) | tmp;
		} else if ((epc_insn & B32M) == B32) {
			child->thread.ss_nextcnt = 2;
			tmp = epc_insn & 0x03FFFFFE;	/* discard LK bit */
			tmp2 = tmp & 0x3FF;
			tmp = (((tmp >> 16) & 0x3FF) << 10) | tmp2; /* 20bit */
			tmp = tmp << 12;
			tmp = (unsigned int)((int) tmp >> 12);
			far_epc = epc + tmp;
			epc += 4;
		} else if ((epc_insn & BR32M) == BR32) {
			child->thread.ss_nextcnt = 2;
			tmp = (epc_insn >> 16) & 0x1F;
			far_epc = regs->regs[tmp];
			epc += 4;
		} else
			epc += 4;
	}

	if (child->thread.ss_nextcnt == 1) {
		read_tsk_long(child, epc, &epc_insn);

		if (is_16bitinsn(epc_insn)) {
			write_tsk_short(child, epc, SINGLESTEP16_INSN);
			ninsn_type = 0;
		} else {
			write_tsk_long(child, epc, SINGLESTEP32_INSN);
			ninsn_type = 1;
		}

		if (ninsn_type == 0) {  /* 16bits */
			child->thread.insn1_type = 0;
			child->thread.addr1 = epc;
			 /* the insn may have 32bit data */
			child->thread.insn1 = (short)epc_insn;
		} else {
			child->thread.insn1_type = 1;
			child->thread.addr1 = epc;
			child->thread.insn1 = epc_insn;
		}
	} else {
		/* branch! have two target child->thread.ss_nextcnt=2 */
		read_tsk_long(child, epc, &epc_insn);
		read_tsk_long(child, far_epc, &far_epc_insn);
		if (is_16bitinsn(epc_insn)) {
			write_tsk_short(child, epc, SINGLESTEP16_INSN);
			ninsn_type = 0;
		} else {
			write_tsk_long(child, epc, SINGLESTEP32_INSN);
			ninsn_type = 1;
		}

		if (ninsn_type == 0) {  /* 16bits */
			child->thread.insn1_type = 0;
			child->thread.addr1 = epc;
			 /* the insn may have 32bit data */
			child->thread.insn1 = (short)epc_insn;
		} else {
			child->thread.insn1_type = 1;
			child->thread.addr1 = epc;
			child->thread.insn1 = epc_insn;
		}

		if (is_16bitinsn(far_epc_insn)) {
			write_tsk_short(child, far_epc, SINGLESTEP16_INSN);
			ninsn_type = 0;
		} else {
			write_tsk_long(child, far_epc, SINGLESTEP32_INSN);
			ninsn_type = 1;
		}

		if (ninsn_type == 0) {  /* 16bits */
			child->thread.insn2_type = 0;
			child->thread.addr2 = far_epc;
			 /* the insn may have 32bit data */
			child->thread.insn2 = (short)far_epc_insn;
		} else {
			child->thread.insn2_type = 1;
			child->thread.addr2 = far_epc;
			child->thread.insn2 = far_epc_insn;
		}
	}
}

void user_disable_single_step(struct task_struct *child)
{
	if (child->thread.insn1_type == 0)
		write_tsk_short(child, child->thread.addr1,
				child->thread.insn1);

	if (child->thread.insn1_type == 1)
		write_tsk_long(child, child->thread.addr1,
				child->thread.insn1);

	if (child->thread.ss_nextcnt == 2) {	/* branch */
		if (child->thread.insn1_type == 0)
			write_tsk_short(child, child->thread.addr1,
					child->thread.insn1);
		if (child->thread.insn1_type == 1)
			write_tsk_long(child, child->thread.addr1,
					child->thread.insn1);
		if (child->thread.insn2_type == 0)
			write_tsk_short(child, child->thread.addr2,
					child->thread.insn2);
		if (child->thread.insn2_type == 1)
			write_tsk_long(child, child->thread.addr2,
					child->thread.insn2);
	}

	child->thread.single_step = 0;
	child->thread.ss_nextcnt = 0;
}

void ptrace_disable(struct task_struct *child)
{
	user_disable_single_step(child);
}

long
arch_ptrace(struct task_struct *child, long request,
	    unsigned long addr, unsigned long data)
{
	int ret;
	unsigned long __user *datap = (void __user *)data;

	switch (request) {
	case PTRACE_GETREGS:
		ret = copy_regset_to_user(child, &user_score_native_view,
						REGSET_GENERAL,
						0, sizeof(struct pt_regs),
						datap);
		break;

	case PTRACE_SETREGS:
		ret = copy_regset_from_user(child, &user_score_native_view,
						REGSET_GENERAL,
						0, sizeof(struct pt_regs),
						datap);
		break;

	default:
		ret = ptrace_request(child, request, addr, data);
		break;
	}

	return ret;
}

/*
 * Notification of system call entry/exit
 * - triggered by current->work.syscall_trace
 */
asmlinkage void do_syscall_trace(struct pt_regs *regs, int entryexit)
{
	if (!(current->ptrace & PT_PTRACED))
		return;

	if (!test_thread_flag(TIF_SYSCALL_TRACE))
		return;

	/* The 0x80 provides a way for the tracing parent to distinguish
	   between a syscall stop and SIGTRAP delivery. */
	ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD) ?
			0x80 : 0));

	/*
	 * this isn't the same as continuing with a signal, but it will do
	 * for normal use.  strace only continues with a signal if the
	 * stopping signal is not SIGTRAP.  -brl
	 */
	if (current->exit_code) {
		send_sig(current->exit_code, current, 1);
		current->exit_code = 0;
	}
}