// SPDX-License-Identifier: GPL-2.0-only
/*
 * Hibernation support for x86-64
 *
 * 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 <linux/scatterlist.h>
#include <linux/kdebug.h>
#include <linux/pgtable.h>

#include <crypto/hash.h>

#include <asm/e820/api.h>
#include <asm/init.h>
#include <asm/proto.h>
#include <asm/page.h>
#include <asm/mtrr.h>
#include <asm/sections.h>
#include <asm/suspend.h>
#include <asm/tlbflush.h>

static int set_up_temporary_text_mapping(pgd_t *pgd)
{
        pmd_t *pmd;
        pud_t *pud;
        p4d_t *p4d = NULL;
        pgprot_t pgtable_prot = __pgprot(_KERNPG_TABLE);
        pgprot_t pmd_text_prot = __pgprot(__PAGE_KERNEL_LARGE_EXEC);

        /* Filter out unsupported __PAGE_KERNEL* bits: */
        pgprot_val(pmd_text_prot) &= __default_kernel_pte_mask;
        pgprot_val(pgtable_prot)  &= __default_kernel_pte_mask;

        /*
         * The new mapping only has to cover the page containing the image
         * kernel's entry point (jump_address_phys), because the switch over to
         * it is carried out by relocated code running from a page allocated
         * specifically for this purpose and covered by the identity mapping, so
         * the temporary kernel text mapping is only needed for the final jump.
         * Moreover, in that mapping the virtual address of the image kernel's
         * entry point must be the same as its virtual address in the image
         * kernel (restore_jump_address), so the image kernel's
         * restore_registers() code doesn't find itself in a different area of
         * the virtual address space after switching over to the original page
         * tables used by the image kernel.
         */

        if (pgtable_l5_enabled()) {
                p4d = (p4d_t *)get_safe_page(GFP_ATOMIC);
                if (!p4d)
                        return -ENOMEM;
        }

        pud = (pud_t *)get_safe_page(GFP_ATOMIC);
        if (!pud)
                return -ENOMEM;

        pmd = (pmd_t *)get_safe_page(GFP_ATOMIC);
        if (!pmd)
                return -ENOMEM;

        set_pmd(pmd + pmd_index(restore_jump_address),
                __pmd((jump_address_phys & PMD_MASK) | pgprot_val(pmd_text_prot)));
        set_pud(pud + pud_index(restore_jump_address),
                __pud(__pa(pmd) | pgprot_val(pgtable_prot)));
        if (p4d) {
                p4d_t new_p4d = __p4d(__pa(pud) | pgprot_val(pgtable_prot));
                pgd_t new_pgd = __pgd(__pa(p4d) | pgprot_val(pgtable_prot));

                set_p4d(p4d + p4d_index(restore_jump_address), new_p4d);
                set_pgd(pgd + pgd_index(restore_jump_address), new_pgd);
        } else {
                /* No p4d for 4-level paging: point the pgd to the pud page table */
                pgd_t new_pgd = __pgd(__pa(pud) | pgprot_val(pgtable_prot));
                set_pgd(pgd + pgd_index(restore_jump_address), new_pgd);
        }

        return 0;
}

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,
                .page_flag      = __PAGE_KERNEL_LARGE_EXEC,
                .offset         = __PAGE_OFFSET,
        };
        unsigned long mstart, mend;
        pgd_t *pgd;
        int result;
        int i;

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

        /* Prepare a temporary mapping for the kernel text */
        result = set_up_temporary_text_mapping(pgd);
        if (result)
                return result;

        /* 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, pgd, mstart, mend);
                if (result)
                        return result;
        }

        temp_pgt = __pa(pgd);
        return 0;
}

asmlinkage int swsusp_arch_resume(void)
{
        int error;

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

        error = relocate_restore_code();
        if (error)
                return error;

        restore_image();
        return 0;
}