Current File : //usr/src/file_protector-1.1-1538/write_protection.h
/**
@file     write_protection.h
@brief    Disable/Enable write protection
@details  Copyright (c) 2024 Acronis International GmbH
@author   Denis Kopyrin (Denis.Kopyrin@acronis.com)
@since    $Id: $
*/

#pragma once

#include "compat.h"

// On 5.3.0 using the legal 'write_cp0' causes panic because WP is not disabled.
// So let's just use out own 'write_cp0' that avoid silly checks.
static inline void wp_cr0(unsigned long cr0)
{
#ifndef KERNEL_MOCK
	// cr0 is protected register in userspace
	__asm__ __volatile__ ("mov %0, %%cr0": "+r"(cr0));
#else
	gCR0 = cr0;
#endif
}

static inline unsigned long disable_write_protect(void)
{
	unsigned long cr0 = read_cr0();
	DPRINTF("cr0=%lX WP=%lX", cr0, (unsigned long)X86_CR0_WP);
	if (cr0 & X86_CR0_WP) {
		wp_cr0(cr0 & ~X86_CR0_WP);
	}
	return cr0;
}

static inline void restore_write_protect(unsigned long saved_cr0)
{
	unsigned long cr0 = read_cr0();
	DPRINTF("cr0=%lX WP=%lX", cr0, (unsigned long)X86_CR0_WP);

	// restore WP-bit of cr0 to pre-disable state
	wp_cr0((cr0 & ~X86_CR0_WP) | (saved_cr0 & X86_CR0_WP));
}