/*
 * handle transition of Linux booting another kernel
 * Copyright (C) 2002-2005 Eric Biederman  <ebiederm@xmission.com>
 *
 * This source code is licensed under the GNU General Public License,
 * Version 2.  See the file COPYING for more details.
 */

#include <linux/mm.h>
#include <linux/kexec.h>
#include <linux/string.h>
#include <linux/reboot.h>
#include <linux/numa.h>
#include <linux/ftrace.h>

#include <asm/pgtable.h>
#include <asm/tlbflush.h>
#include <asm/mmu_context.h>
#include <asm/io.h>

#define PAGE_ALIGNED __attribute__ ((__aligned__(PAGE_SIZE)))
static u64 kexec_pgd[512] PAGE_ALIGNED;
static u64 kexec_pud0[512] PAGE_ALIGNED;
static u64 kexec_pmd0[512] PAGE_ALIGNED;
static u64 kexec_pte0[512] PAGE_ALIGNED;
static u64 kexec_pud1[512] PAGE_ALIGNED;
static u64 kexec_pmd1[512] PAGE_ALIGNED;
static u64 kexec_pte1[512] PAGE_ALIGNED;

static void init_level2_page(pmd_t *level2p, unsigned long addr)
{
        unsigned long end_addr;

        addr &= PAGE_MASK;
        end_addr = addr + PUD_SIZE;
        while (addr < end_addr) {
                set_pmd(level2p++, __pmd(addr | __PAGE_KERNEL_LARGE_EXEC));
                addr += PMD_SIZE;
        }
}

static int init_level3_page(struct kimage *image, pud_t *level3p,
                                unsigned long addr, unsigned long last_addr)
{
        unsigned long end_addr;
        int result;

        result = 0;
        addr &= PAGE_MASK;
        end_addr = addr + PGDIR_SIZE;
        while ((addr < last_addr) && (addr < end_addr)) {
                struct page *page;
                pmd_t *level2p;

                page = kimage_alloc_control_pages(image, 0);
                if (!page) {
                        result = -ENOMEM;
                        goto out;
                }
                level2p = (pmd_t *)page_address(page);
                init_level2_page(level2p, addr);
                set_pud(level3p++, __pud(__pa(level2p) | _KERNPG_TABLE));
                addr += PUD_SIZE;
        }
        /* clear the unused entries */
        while (addr < end_addr) {
                pud_clear(level3p++);
                addr += PUD_SIZE;
        }
out:
        return result;
}


static int init_level4_page(struct kimage *image, pgd_t *level4p,
                                unsigned long addr, unsigned long last_addr)
{
        unsigned long end_addr;
        int result;

        result = 0;
        addr &= PAGE_MASK;
        end_addr = addr + (PTRS_PER_PGD * PGDIR_SIZE);
        while ((addr < last_addr) && (addr < end_addr)) {
                struct page *page;
                pud_t *level3p;

                page = kimage_alloc_control_pages(image, 0);
                if (!page) {
                        result = -ENOMEM;
                        goto out;
                }
                level3p = (pud_t *)page_address(page);
                result = init_level3_page(image, level3p, addr, last_addr);
                if (result) {
                        goto out;
                }
                set_pgd(level4p++, __pgd(__pa(level3p) | _KERNPG_TABLE));
                addr += PGDIR_SIZE;
        }
        /* clear the unused entries */
        while (addr < end_addr) {
                pgd_clear(level4p++);
                addr += PGDIR_SIZE;
        }
out:
        return result;
}


static int init_pgtable(struct kimage *image, unsigned long start_pgtable)
{
        pgd_t *level4p;
        level4p = (pgd_t *)__va(start_pgtable);
        return init_level4_page(image, level4p, 0, max_pfn << PAGE_SHIFT);
}

static void set_idt(void *newidt, u16 limit)
{
        struct desc_ptr curidt;

        /* x86-64 supports unaliged loads & stores */
        curidt.size    = limit;
        curidt.address = (unsigned long)newidt;

        __asm__ __volatile__ (
                "lidtq %0\n"
                : : "m" (curidt)
                );
};


static void set_gdt(void *newgdt, u16 limit)
{
        struct desc_ptr curgdt;

        /* x86-64 supports unaligned loads & stores */
        curgdt.size    = limit;
        curgdt.address = (unsigned long)newgdt;

        __asm__ __volatile__ (
                "lgdtq %0\n"
                : : "m" (curgdt)
                );
};

static void load_segments(void)
{
        __asm__ __volatile__ (
                "\tmovl %0,%%ds\n"
                "\tmovl %0,%%es\n"
                "\tmovl %0,%%ss\n"
                "\tmovl %0,%%fs\n"
                "\tmovl %0,%%gs\n"
                : : "a" (__KERNEL_DS) : "memory"
                );
}

int machine_kexec_prepare(struct kimage *image)
{
        unsigned long start_pgtable;
        int result;

        /* Calculate the offsets */
        start_pgtable = page_to_pfn(image->control_code_page) << PAGE_SHIFT;

        /* Setup the identity mapped 64bit page table */
        result = init_pgtable(image, start_pgtable);
        if (result)
                return result;

        return 0;
}

void machine_kexec_cleanup(struct kimage *image)
{
        return;
}

/*
 * Do not allocate memory (or fail in any way) in machine_kexec().
 * We are past the point of no return, committed to rebooting now.
 */
void machine_kexec(struct kimage *image)
{
        unsigned long page_list[PAGES_NR];
        void *control_page;

        tracer_disable();

        /* Interrupts aren't acceptable while we reboot */
        local_irq_disable();

        control_page = page_address(image->control_code_page) + PAGE_SIZE;
        memcpy(control_page, relocate_kernel, PAGE_SIZE);

        page_list[PA_CONTROL_PAGE] = virt_to_phys(control_page);
        page_list[VA_CONTROL_PAGE] = (unsigned long)relocate_kernel;
        page_list[PA_PGD] = virt_to_phys(&kexec_pgd);
        page_list[VA_PGD] = (unsigned long)kexec_pgd;
        page_list[PA_PUD_0] = virt_to_phys(&kexec_pud0);
        page_list[VA_PUD_0] = (unsigned long)kexec_pud0;
        page_list[PA_PMD_0] = virt_to_phys(&kexec_pmd0);
        page_list[VA_PMD_0] = (unsigned long)kexec_pmd0;
        page_list[PA_PTE_0] = virt_to_phys(&kexec_pte0);
        page_list[VA_PTE_0] = (unsigned long)kexec_pte0;
        page_list[PA_PUD_1] = virt_to_phys(&kexec_pud1);
        page_list[VA_PUD_1] = (unsigned long)kexec_pud1;
        page_list[PA_PMD_1] = virt_to_phys(&kexec_pmd1);
        page_list[VA_PMD_1] = (unsigned long)kexec_pmd1;
        page_list[PA_PTE_1] = virt_to_phys(&kexec_pte1);
        page_list[VA_PTE_1] = (unsigned long)kexec_pte1;

        page_list[PA_TABLE_PAGE] =
          (unsigned long)__pa(page_address(image->control_code_page));

        /* The segment registers are funny things, they have both a
         * visible and an invisible part.  Whenever the visible part is
         * set to a specific selector, the invisible part is loaded
         * with from a table in memory.  At no other time is the
         * descriptor table in memory accessed.
         *
         * I take advantage of this here by force loading the
         * segments, before I zap the gdt with an invalid value.
         */
        load_segments();
        /* The gdt & idt are now invalid.
         * If you want to load them you must set up your own idt & gdt.
         */
        set_gdt(phys_to_virt(0),0);
        set_idt(phys_to_virt(0),0);

        /* now call it */
        relocate_kernel((unsigned long)image->head, (unsigned long)page_list,
                        image->start);
}

void arch_crash_save_vmcoreinfo(void)
{
        VMCOREINFO_SYMBOL(phys_base);
        VMCOREINFO_SYMBOL(init_level4_pgt);

#ifdef CONFIG_NUMA
        VMCOREINFO_SYMBOL(node_data);
        VMCOREINFO_LENGTH(node_data, MAX_NUMNODES);
#endif
}