/*
 * Hibernation support for x86-64
 *
 * Distribute under GPLv2
 *
 * Copyright (c) 2007 Rafael J. Wysocki <rjw@sisk.pl>
 * Copyright (c) 2002 Pavel Machek <pavel@ucw.cz>
 * Copyright (c) 2001 Patrick Mochel <mochel@osdl.org>
 */

#include <linux/gfp.h>
#include <linux/smp.h>
#include <linux/suspend.h>

#include <asm/init.h>
#include <asm/proto.h>
#include <asm/page.h>
#include <asm/pgtable.h>
#include <asm/mtrr.h>
#include <asm/suspend.h>

/* References to section boundaries */
extern __visible const void __nosave_begin, __nosave_end;

/* Defined in hibernate_asm_64.S */
extern asmlinkage int restore_image(void);

/*
 * Address to jump to in the last phase of restore in order to get to the image
 * kernel's text (this value is passed in the image header).
 */
unsigned long restore_jump_address __visible;

/*
 * Value of the cr3 register from before the hibernation (this value is passed
 * in the image header).
 */
unsigned long restore_cr3 __visible;

pgd_t *temp_level4_pgt __visible;

void *relocated_restore_code __visible;

static void *alloc_pgt_page(void *context)
{
	return (void *)get_safe_page(GFP_ATOMIC);
}

static int set_up_temporary_mappings(void)
{
	struct x86_mapping_info info = {
		.alloc_pgt_page	= alloc_pgt_page,
		.pmd_flag	= __PAGE_KERNEL_LARGE_EXEC,
		.kernel_mapping = true,
	};
	unsigned long mstart, mend;
	int result;
	int i;

	temp_level4_pgt = (pgd_t *)get_safe_page(GFP_ATOMIC);
	if (!temp_level4_pgt)
		return -ENOMEM;

	/* It is safe to reuse the original kernel mapping */
	set_pgd(temp_level4_pgt + pgd_index(__START_KERNEL_map),
		init_level4_pgt[pgd_index(__START_KERNEL_map)]);

	/* Set up the direct mapping from scratch */
	for (i = 0; i < nr_pfn_mapped; i++) {
		mstart = pfn_mapped[i].start << PAGE_SHIFT;
		mend   = pfn_mapped[i].end << PAGE_SHIFT;

		result = kernel_ident_mapping_init(&info, temp_level4_pgt,
						   mstart, mend);

		if (result)
			return result;
	}

	return 0;
}

int swsusp_arch_resume(void)
{
	int error;

	/* We have got enough memory and from now on we cannot recover */
	if ((error = set_up_temporary_mappings()))
		return error;

	relocated_restore_code = (void *)get_safe_page(GFP_ATOMIC);
	if (!relocated_restore_code)
		return -ENOMEM;
	memcpy(relocated_restore_code, &core_restore_code,
	       &restore_registers - &core_restore_code);

	restore_image();
	return 0;
}

/*
 *	pfn_is_nosave - check if given pfn is in the 'nosave' section
 */

int pfn_is_nosave(unsigned long pfn)
{
	unsigned long nosave_begin_pfn = __pa_symbol(&__nosave_begin) >> PAGE_SHIFT;
	unsigned long nosave_end_pfn = PAGE_ALIGN(__pa_symbol(&__nosave_end)) >> PAGE_SHIFT;
	return (pfn >= nosave_begin_pfn) && (pfn < nosave_end_pfn);
}

struct restore_data_record {
	unsigned long jump_address;
	unsigned long cr3;
	unsigned long magic;
};

#define RESTORE_MAGIC	0x0123456789ABCDEFUL

/**
 *	arch_hibernation_header_save - populate the architecture specific part
 *		of a hibernation image header
 *	@addr: address to save the data at
 */
int arch_hibernation_header_save(void *addr, unsigned int max_size)
{
	struct restore_data_record *rdr = addr;

	if (max_size < sizeof(struct restore_data_record))
		return -EOVERFLOW;
	rdr->jump_address = restore_jump_address;
	rdr->cr3 = restore_cr3;
	rdr->magic = RESTORE_MAGIC;
	return 0;
}

/**
 *	arch_hibernation_header_restore - read the architecture specific data
 *		from the hibernation image header
 *	@addr: address to read the data from
 */
int arch_hibernation_header_restore(void *addr)
{
	struct restore_data_record *rdr = addr;

	restore_jump_address = rdr->jump_address;
	restore_cr3 = rdr->cr3;
	return (rdr->magic == RESTORE_MAGIC) ? 0 : -EINVAL;
}