/*
 * 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/delay.h>
#include <linux/init.h>
#include <linux/numa.h>
#include <linux/ftrace.h>
#include <linux/suspend.h>

#include <asm/pgtable.h>
#include <asm/pgalloc.h>
#include <asm/tlbflush.h>
#include <asm/mmu_context.h>
#include <asm/io.h>
#include <asm/apic.h>
#include <asm/cpufeature.h>
#include <asm/desc.h>
#include <asm/system.h>
#include <asm/cacheflush.h>

#define PAGE_ALIGNED __attribute__ ((__aligned__(PAGE_SIZE)))
static u32 kexec_pgd[1024] PAGE_ALIGNED;
#ifdef CONFIG_X86_PAE
static u32 kexec_pmd0[1024] PAGE_ALIGNED;
static u32 kexec_pmd1[1024] PAGE_ALIGNED;
#endif
static u32 kexec_pte0[1024] PAGE_ALIGNED;
static u32 kexec_pte1[1024] PAGE_ALIGNED;

static void set_idt(void *newidt, __u16 limit)
{
        struct desc_ptr curidt;

        /* ia32 supports unaliged loads & stores */
        curidt.size    = limit;
        curidt.address = (unsigned long)newidt;

        load_idt(&curidt);
}


static void set_gdt(void *newgdt, __u16 limit)
{
        struct desc_ptr curgdt;

        /* ia32 supports unaligned loads & stores */
        curgdt.size    = limit;
        curgdt.address = (unsigned long)newgdt;

        load_gdt(&curgdt);
}

static void load_segments(void)
{
#define __STR(X) #X
#define STR(X) __STR(X)

        __asm__ __volatile__ (
                "\tljmp $"STR(__KERNEL_CS)",$1f\n"
                "\t1:\n"
                "\tmovl $"STR(__KERNEL_DS)",%%eax\n"
                "\tmovl %%eax,%%ds\n"
                "\tmovl %%eax,%%es\n"
                "\tmovl %%eax,%%fs\n"
                "\tmovl %%eax,%%gs\n"
                "\tmovl %%eax,%%ss\n"
                ::: "eax", "memory");
#undef STR
#undef __STR
}

/*
 * A architecture hook called to validate the
 * proposed image and prepare the control pages
 * as needed.  The pages for KEXEC_CONTROL_PAGE_SIZE
 * have been allocated, but the segments have yet
 * been copied into the kernel.
 *
 * Do what every setup is needed on image and the
 * reboot code buffer to allow us to avoid allocations
 * later.
 *
 * Make control page executable.
 */
int machine_kexec_prepare(struct kimage *image)
{
        if (nx_enabled)
                set_pages_x(image->control_code_page, 1);
        return 0;
}

/*
 * Undo anything leftover by machine_kexec_prepare
 * when an image is freed.
 */
void machine_kexec_cleanup(struct kimage *image)
{
        if (nx_enabled)
                set_pages_nx(image->control_code_page, 1);
}

/*
 * 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;
        int save_ftrace_enabled;
        asmlinkage unsigned long
                (*relocate_kernel_ptr)(unsigned long indirection_page,
                                       unsigned long control_page,
                                       unsigned long start_address,
                                       unsigned int has_pae,
                                       unsigned int preserve_context);

#ifdef CONFIG_KEXEC_JUMP
        if (kexec_image->preserve_context)
                save_processor_state();
#endif

        save_ftrace_enabled = __ftrace_enabled_save();

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

        if (image->preserve_context) {
#ifdef CONFIG_X86_IO_APIC
                /* We need to put APICs in legacy mode so that we can
                 * get timer interrupts in second kernel. kexec/kdump
                 * paths already have calls to disable_IO_APIC() in
                 * one form or other. kexec jump path also need
                 * one.
                 */
                disable_IO_APIC();
#endif
        }

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

        relocate_kernel_ptr = control_page;
        page_list[PA_CONTROL_PAGE] = __pa(control_page);
        page_list[VA_CONTROL_PAGE] = (unsigned long)control_page;
        page_list[PA_PGD] = __pa(kexec_pgd);
        page_list[VA_PGD] = (unsigned long)kexec_pgd;
#ifdef CONFIG_X86_PAE
        page_list[PA_PMD_0] = __pa(kexec_pmd0);
        page_list[VA_PMD_0] = (unsigned long)kexec_pmd0;
        page_list[PA_PMD_1] = __pa(kexec_pmd1);
        page_list[VA_PMD_1] = (unsigned long)kexec_pmd1;
#endif
        page_list[PA_PTE_0] = __pa(kexec_pte0);
        page_list[VA_PTE_0] = (unsigned long)kexec_pte0;
        page_list[PA_PTE_1] = __pa(kexec_pte1);
        page_list[VA_PTE_1] = (unsigned long)kexec_pte1;

        if (image->type == KEXEC_TYPE_DEFAULT)
                page_list[PA_SWAP_PAGE] = (page_to_pfn(image->swap_page)
                                                << PAGE_SHIFT);

        /* 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 */
        image->start = relocate_kernel_ptr((unsigned long)image->head,
                                           (unsigned long)page_list,
                                           image->start, cpu_has_pae,
                                           image->preserve_context);

#ifdef CONFIG_KEXEC_JUMP
        if (kexec_image->preserve_context)
                restore_processor_state();
#endif

        __ftrace_enabled_restore(save_ftrace_enabled);
}

void arch_crash_save_vmcoreinfo(void)
{
#ifdef CONFIG_NUMA
        VMCOREINFO_SYMBOL(node_data);
        VMCOREINFO_LENGTH(node_data, MAX_NUMNODES);
#endif
#ifdef CONFIG_X86_PAE
        VMCOREINFO_CONFIG(X86_PAE);
#endif
}