/*
 * Kexec bzImage loader
 *
 * Copyright (C) 2014 Red Hat Inc.
 * Authors:
 *      Vivek Goyal <vgoyal@redhat.com>
 *
 * This source code is licensed under the GNU General Public License,
 * Version 2.  See the file COPYING for more details.
 */

#define pr_fmt(fmt)     "kexec-bzImage64: " fmt

#include <linux/string.h>
#include <linux/printk.h>
#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/kexec.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/efi.h>
#include <linux/verification.h>

#include <asm/bootparam.h>
#include <asm/setup.h>
#include <asm/crash.h>
#include <asm/efi.h>
#include <asm/e820/api.h>
#include <asm/kexec-bzimage64.h>

#define MAX_ELFCOREHDR_STR_LEN  30      /* elfcorehdr=0x<64bit-value> */

/*
 * Defines lowest physical address for various segments. Not sure where
 * exactly these limits came from. Current bzimage64 loader in kexec-tools
 * uses these so I am retaining it. It can be changed over time as we gain
 * more insight.
 */
#define MIN_PURGATORY_ADDR      0x3000
#define MIN_BOOTPARAM_ADDR      0x3000
#define MIN_KERNEL_LOAD_ADDR    0x100000
#define MIN_INITRD_LOAD_ADDR    0x1000000

/*
 * This is a place holder for all boot loader specific data structure which
 * gets allocated in one call but gets freed much later during cleanup
 * time. Right now there is only one field but it can grow as need be.
 */
struct bzimage64_data {
        /*
         * Temporary buffer to hold bootparams buffer. This should be
         * freed once the bootparam segment has been loaded.
         */
        void *bootparams_buf;
};

static int setup_initrd(struct boot_params *params,
                unsigned long initrd_load_addr, unsigned long initrd_len)
{
        params->hdr.ramdisk_image = initrd_load_addr & 0xffffffffUL;
        params->hdr.ramdisk_size = initrd_len & 0xffffffffUL;

        params->ext_ramdisk_image = initrd_load_addr >> 32;
        params->ext_ramdisk_size = initrd_len >> 32;

        return 0;
}

static int setup_cmdline(struct kimage *image, struct boot_params *params,
                         unsigned long bootparams_load_addr,
                         unsigned long cmdline_offset, char *cmdline,
                         unsigned long cmdline_len)
{
        char *cmdline_ptr = ((char *)params) + cmdline_offset;
        unsigned long cmdline_ptr_phys, len = 0;
        uint32_t cmdline_low_32, cmdline_ext_32;

        if (image->type == KEXEC_TYPE_CRASH) {
                len = sprintf(cmdline_ptr,
                        "elfcorehdr=0x%lx ", image->arch.elf_load_addr);
        }
        memcpy(cmdline_ptr + len, cmdline, cmdline_len);
        cmdline_len += len;

        cmdline_ptr[cmdline_len - 1] = '\0';

        pr_debug("Final command line is: %s\n", cmdline_ptr);
        cmdline_ptr_phys = bootparams_load_addr + cmdline_offset;
        cmdline_low_32 = cmdline_ptr_phys & 0xffffffffUL;
        cmdline_ext_32 = cmdline_ptr_phys >> 32;

        params->hdr.cmd_line_ptr = cmdline_low_32;
        if (cmdline_ext_32)
                params->ext_cmd_line_ptr = cmdline_ext_32;

        return 0;
}

static int setup_e820_entries(struct boot_params *params)
{
        unsigned int nr_e820_entries;

        nr_e820_entries = e820_table_kexec->nr_entries;

        /* TODO: Pass entries more than E820_MAX_ENTRIES_ZEROPAGE in bootparams setup data */
        if (nr_e820_entries > E820_MAX_ENTRIES_ZEROPAGE)
                nr_e820_entries = E820_MAX_ENTRIES_ZEROPAGE;

        params->e820_entries = nr_e820_entries;
        memcpy(&params->e820_table, &e820_table_kexec->entries, nr_e820_entries*sizeof(struct e820_entry));

        return 0;
}

#ifdef CONFIG_EFI
static int setup_efi_info_memmap(struct boot_params *params,
                                  unsigned long params_load_addr,
                                  unsigned int efi_map_offset,
                                  unsigned int efi_map_sz)
{
        void *efi_map = (void *)params + efi_map_offset;
        unsigned long efi_map_phys_addr = params_load_addr + efi_map_offset;
        struct efi_info *ei = &params->efi_info;

        if (!efi_map_sz)
                return 0;

        efi_runtime_map_copy(efi_map, efi_map_sz);

        ei->efi_memmap = efi_map_phys_addr & 0xffffffff;
        ei->efi_memmap_hi = efi_map_phys_addr >> 32;
        ei->efi_memmap_size = efi_map_sz;

        return 0;
}

static int
prepare_add_efi_setup_data(struct boot_params *params,
                       unsigned long params_load_addr,
                       unsigned int efi_setup_data_offset)
{
        unsigned long setup_data_phys;
        struct setup_data *sd = (void *)params + efi_setup_data_offset;
        struct efi_setup_data *esd = (void *)sd + sizeof(struct setup_data);

        esd->fw_vendor = efi.fw_vendor;
        esd->runtime = efi.runtime;
        esd->tables = efi.config_table;
        esd->smbios = efi.smbios;

        sd->type = SETUP_EFI;
        sd->len = sizeof(struct efi_setup_data);

        /* Add setup data */
        setup_data_phys = params_load_addr + efi_setup_data_offset;
        sd->next = params->hdr.setup_data;
        params->hdr.setup_data = setup_data_phys;

        return 0;
}

static int
setup_efi_state(struct boot_params *params, unsigned long params_load_addr,
                unsigned int efi_map_offset, unsigned int efi_map_sz,
                unsigned int efi_setup_data_offset)
{
        struct efi_info *current_ei = &boot_params.efi_info;
        struct efi_info *ei = &params->efi_info;

        if (!current_ei->efi_memmap_size)
                return 0;

        /*
         * If 1:1 mapping is not enabled, second kernel can not setup EFI
         * and use EFI run time services. User space will have to pass
         * acpi_rsdp=<addr> on kernel command line to make second kernel boot
         * without efi.
         */
        if (efi_enabled(EFI_OLD_MEMMAP))
                return 0;

        ei->efi_loader_signature = current_ei->efi_loader_signature;
        ei->efi_systab = current_ei->efi_systab;
        ei->efi_systab_hi = current_ei->efi_systab_hi;

        ei->efi_memdesc_version = current_ei->efi_memdesc_version;
        ei->efi_memdesc_size = efi_get_runtime_map_desc_size();

        setup_efi_info_memmap(params, params_load_addr, efi_map_offset,
                              efi_map_sz);
        prepare_add_efi_setup_data(params, params_load_addr,
                                   efi_setup_data_offset);
        return 0;
}
#endif /* CONFIG_EFI */

static int
setup_boot_parameters(struct kimage *image, struct boot_params *params,
                      unsigned long params_load_addr,
                      unsigned int efi_map_offset, unsigned int efi_map_sz,
                      unsigned int efi_setup_data_offset)
{
        unsigned int nr_e820_entries;
        unsigned long long mem_k, start, end;
        int i, ret = 0;

        /* Get subarch from existing bootparams */
        params->hdr.hardware_subarch = boot_params.hdr.hardware_subarch;

        /* Copying screen_info will do? */
        memcpy(&params->screen_info, &boot_params.screen_info,
                                sizeof(struct screen_info));

        /* Fill in memsize later */
        params->screen_info.ext_mem_k = 0;
        params->alt_mem_k = 0;

        /* Default APM info */
        memset(&params->apm_bios_info, 0, sizeof(params->apm_bios_info));

        /* Default drive info */
        memset(&params->hd0_info, 0, sizeof(params->hd0_info));
        memset(&params->hd1_info, 0, sizeof(params->hd1_info));

        if (image->type == KEXEC_TYPE_CRASH) {
                ret = crash_setup_memmap_entries(image, params);
                if (ret)
                        return ret;
        } else
                setup_e820_entries(params);

        nr_e820_entries = params->e820_entries;

        for (i = 0; i < nr_e820_entries; i++) {
                if (params->e820_table[i].type != E820_TYPE_RAM)
                        continue;
                start = params->e820_table[i].addr;
                end = params->e820_table[i].addr + params->e820_table[i].size - 1;

                if ((start <= 0x100000) && end > 0x100000) {
                        mem_k = (end >> 10) - (0x100000 >> 10);
                        params->screen_info.ext_mem_k = mem_k;
                        params->alt_mem_k = mem_k;
                        if (mem_k > 0xfc00)
                                params->screen_info.ext_mem_k = 0xfc00; /* 64M*/
                        if (mem_k > 0xffffffff)
                                params->alt_mem_k = 0xffffffff;
                }
        }

#ifdef CONFIG_EFI
        /* Setup EFI state */
        setup_efi_state(params, params_load_addr, efi_map_offset, efi_map_sz,
                        efi_setup_data_offset);
#endif

        /* Setup EDD info */
        memcpy(params->eddbuf, boot_params.eddbuf,
                                EDDMAXNR * sizeof(struct edd_info));
        params->eddbuf_entries = boot_params.eddbuf_entries;

        memcpy(params->edd_mbr_sig_buffer, boot_params.edd_mbr_sig_buffer,
               EDD_MBR_SIG_MAX * sizeof(unsigned int));

        return ret;
}

static int bzImage64_probe(const char *buf, unsigned long len)
{
        int ret = -ENOEXEC;
        struct setup_header *header;

        /* kernel should be at least two sectors long */
        if (len < 2 * 512) {
                pr_err("File is too short to be a bzImage\n");
                return ret;
        }

        header = (struct setup_header *)(buf + offsetof(struct boot_params, hdr));
        if (memcmp((char *)&header->header, "HdrS", 4) != 0) {
                pr_err("Not a bzImage\n");
                return ret;
        }

        if (header->boot_flag != 0xAA55) {
                pr_err("No x86 boot sector present\n");
                return ret;
        }

        if (header->version < 0x020C) {
                pr_err("Must be at least protocol version 2.12\n");
                return ret;
        }

        if (!(header->loadflags & LOADED_HIGH)) {
                pr_err("zImage not a bzImage\n");
                return ret;
        }

        if (!(header->xloadflags & XLF_KERNEL_64)) {
                pr_err("Not a bzImage64. XLF_KERNEL_64 is not set.\n");
                return ret;
        }

        if (!(header->xloadflags & XLF_CAN_BE_LOADED_ABOVE_4G)) {
                pr_err("XLF_CAN_BE_LOADED_ABOVE_4G is not set.\n");
                return ret;
        }

        /*
         * Can't handle 32bit EFI as it does not allow loading kernel
         * above 4G. This should be handled by 32bit bzImage loader
         */
        if (efi_enabled(EFI_RUNTIME_SERVICES) && !efi_enabled(EFI_64BIT)) {
                pr_debug("EFI is 32 bit. Can't load kernel above 4G.\n");
                return ret;
        }

        /* I've got a bzImage */
        pr_debug("It's a relocatable bzImage64\n");
        ret = 0;

        return ret;
}

static void *bzImage64_load(struct kimage *image, char *kernel,
                            unsigned long kernel_len, char *initrd,
                            unsigned long initrd_len, char *cmdline,
                            unsigned long cmdline_len)
{

        struct setup_header *header;
        int setup_sects, kern16_size, ret = 0;
        unsigned long setup_header_size, params_cmdline_sz;
        struct boot_params *params;
        unsigned long bootparam_load_addr, kernel_load_addr, initrd_load_addr;
        unsigned long purgatory_load_addr;
        struct bzimage64_data *ldata;
        struct kexec_entry64_regs regs64;
        void *stack;
        unsigned int setup_hdr_offset = offsetof(struct boot_params, hdr);
        unsigned int efi_map_offset, efi_map_sz, efi_setup_data_offset;
        struct kexec_buf kbuf = { .image = image, .buf_max = ULONG_MAX,
                                  .top_down = true };

        header = (struct setup_header *)(kernel + setup_hdr_offset);
        setup_sects = header->setup_sects;
        if (setup_sects == 0)
                setup_sects = 4;

        kern16_size = (setup_sects + 1) * 512;
        if (kernel_len < kern16_size) {
                pr_err("bzImage truncated\n");
                return ERR_PTR(-ENOEXEC);
        }

        if (cmdline_len > header->cmdline_size) {
                pr_err("Kernel command line too long\n");
                return ERR_PTR(-EINVAL);
        }

        /*
         * In case of crash dump, we will append elfcorehdr=<addr> to
         * command line. Make sure it does not overflow
         */
        if (cmdline_len + MAX_ELFCOREHDR_STR_LEN > header->cmdline_size) {
                pr_debug("Appending elfcorehdr=<addr> to command line exceeds maximum allowed length\n");
                return ERR_PTR(-EINVAL);
        }

        /* Allocate and load backup region */
        if (image->type == KEXEC_TYPE_CRASH) {
                ret = crash_load_segments(image);
                if (ret)
                        return ERR_PTR(ret);
        }

        /*
         * Load purgatory. For 64bit entry point, purgatory  code can be
         * anywhere.
         */
        ret = kexec_load_purgatory(image, MIN_PURGATORY_ADDR, ULONG_MAX, 1,
                                   &purgatory_load_addr);
        if (ret) {
                pr_err("Loading purgatory failed\n");
                return ERR_PTR(ret);
        }

        pr_debug("Loaded purgatory at 0x%lx\n", purgatory_load_addr);


        /*
         * Load Bootparams and cmdline and space for efi stuff.
         *
         * Allocate memory together for multiple data structures so
         * that they all can go in single area/segment and we don't
         * have to create separate segment for each. Keeps things
         * little bit simple
         */
        efi_map_sz = efi_get_runtime_map_size();
        efi_map_sz = ALIGN(efi_map_sz, 16);
        params_cmdline_sz = sizeof(struct boot_params) + cmdline_len +
                                MAX_ELFCOREHDR_STR_LEN;
        params_cmdline_sz = ALIGN(params_cmdline_sz, 16);
        kbuf.bufsz = params_cmdline_sz + efi_map_sz +
                                sizeof(struct setup_data) +
                                sizeof(struct efi_setup_data);

        params = kzalloc(kbuf.bufsz, GFP_KERNEL);
        if (!params)
                return ERR_PTR(-ENOMEM);
        efi_map_offset = params_cmdline_sz;
        efi_setup_data_offset = efi_map_offset + efi_map_sz;

        /* Copy setup header onto bootparams. Documentation/x86/boot.txt */
        setup_header_size = 0x0202 + kernel[0x0201] - setup_hdr_offset;

        /* Is there a limit on setup header size? */
        memcpy(&params->hdr, (kernel + setup_hdr_offset), setup_header_size);

        kbuf.buffer = params;
        kbuf.memsz = kbuf.bufsz;
        kbuf.buf_align = 16;
        kbuf.buf_min = MIN_BOOTPARAM_ADDR;
        ret = kexec_add_buffer(&kbuf);
        if (ret)
                goto out_free_params;
        bootparam_load_addr = kbuf.mem;
        pr_debug("Loaded boot_param, command line and misc at 0x%lx bufsz=0x%lx memsz=0x%lx\n",
                 bootparam_load_addr, kbuf.bufsz, kbuf.bufsz);

        /* Load kernel */
        kbuf.buffer = kernel + kern16_size;
        kbuf.bufsz =  kernel_len - kern16_size;
        kbuf.memsz = PAGE_ALIGN(header->init_size);
        kbuf.buf_align = header->kernel_alignment;
        kbuf.buf_min = MIN_KERNEL_LOAD_ADDR;
        ret = kexec_add_buffer(&kbuf);
        if (ret)
                goto out_free_params;
        kernel_load_addr = kbuf.mem;

        pr_debug("Loaded 64bit kernel at 0x%lx bufsz=0x%lx memsz=0x%lx\n",
                 kernel_load_addr, kbuf.bufsz, kbuf.memsz);

        /* Load initrd high */
        if (initrd) {
                kbuf.buffer = initrd;
                kbuf.bufsz = kbuf.memsz = initrd_len;
                kbuf.buf_align = PAGE_SIZE;
                kbuf.buf_min = MIN_INITRD_LOAD_ADDR;
                ret = kexec_add_buffer(&kbuf);
                if (ret)
                        goto out_free_params;
                initrd_load_addr = kbuf.mem;

                pr_debug("Loaded initrd at 0x%lx bufsz=0x%lx memsz=0x%lx\n",
                                initrd_load_addr, initrd_len, initrd_len);

                setup_initrd(params, initrd_load_addr, initrd_len);
        }

        setup_cmdline(image, params, bootparam_load_addr,
                      sizeof(struct boot_params), cmdline, cmdline_len);

        /* bootloader info. Do we need a separate ID for kexec kernel loader? */
        params->hdr.type_of_loader = 0x0D << 4;
        params->hdr.loadflags = 0;

        /* Setup purgatory regs for entry */
        ret = kexec_purgatory_get_set_symbol(image, "entry64_regs", &regs64,
                                             sizeof(regs64), 1);
        if (ret)
                goto out_free_params;

        regs64.rbx = 0; /* Bootstrap Processor */
        regs64.rsi = bootparam_load_addr;
        regs64.rip = kernel_load_addr + 0x200;
        stack = kexec_purgatory_get_symbol_addr(image, "stack_end");
        if (IS_ERR(stack)) {
                pr_err("Could not find address of symbol stack_end\n");
                ret = -EINVAL;
                goto out_free_params;
        }

        regs64.rsp = (unsigned long)stack;
        ret = kexec_purgatory_get_set_symbol(image, "entry64_regs", &regs64,
                                             sizeof(regs64), 0);
        if (ret)
                goto out_free_params;

        ret = setup_boot_parameters(image, params, bootparam_load_addr,
                                    efi_map_offset, efi_map_sz,
                                    efi_setup_data_offset);
        if (ret)
                goto out_free_params;

        /* Allocate loader specific data */
        ldata = kzalloc(sizeof(struct bzimage64_data), GFP_KERNEL);
        if (!ldata) {
                ret = -ENOMEM;
                goto out_free_params;
        }

        /*
         * Store pointer to params so that it could be freed after loading
         * params segment has been loaded and contents have been copied
         * somewhere else.
         */
        ldata->bootparams_buf = params;
        return ldata;

out_free_params:
        kfree(params);
        return ERR_PTR(ret);
}

/* This cleanup function is called after various segments have been loaded */
static int bzImage64_cleanup(void *loader_data)
{
        struct bzimage64_data *ldata = loader_data;

        if (!ldata)
                return 0;

        kfree(ldata->bootparams_buf);
        ldata->bootparams_buf = NULL;

        return 0;
}

#ifdef CONFIG_KEXEC_BZIMAGE_VERIFY_SIG
static int bzImage64_verify_sig(const char *kernel, unsigned long kernel_len)
{
        return verify_pefile_signature(kernel, kernel_len,
                                       NULL,
                                       VERIFYING_KEXEC_PE_SIGNATURE);
}
#endif

struct kexec_file_ops kexec_bzImage64_ops = {
        .probe = bzImage64_probe,
        .load = bzImage64_load,
        .cleanup = bzImage64_cleanup,
#ifdef CONFIG_KEXEC_BZIMAGE_VERIFY_SIG
        .verify_sig = bzImage64_verify_sig,
#endif
};