// SPDX-License-Identifier: GPL-2.0-only
/*
 * ppc64 code to implement the kexec_file_load syscall
 *
 * Copyright (C) 2004  Adam Litke (agl@us.ibm.com)
 * Copyright (C) 2004  IBM Corp.
 * Copyright (C) 2004,2005  Milton D Miller II, IBM Corporation
 * Copyright (C) 2005  R Sharada (sharada@in.ibm.com)
 * Copyright (C) 2006  Mohan Kumar M (mohan@in.ibm.com)
 * Copyright (C) 2016  IBM Corporation
 *
 * Based on kexec-tools' kexec-elf-ppc64.c, fs2dt.c.
 * Heavily modified for the kernel by
 * Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>.
 */

#include <linux/slab.h>
#include <linux/kexec.h>
#include <linux/of_fdt.h>
#include <linux/libfdt.h>
#include <asm/ima.h>

#define SLAVE_CODE_SIZE         256

const struct kexec_file_ops * const kexec_file_loaders[] = {
        &kexec_elf64_ops,
        NULL
};

int arch_kexec_kernel_image_probe(struct kimage *image, void *buf,
                                  unsigned long buf_len)
{
        /* We don't support crash kernels yet. */
        if (image->type == KEXEC_TYPE_CRASH)
                return -EOPNOTSUPP;

        return kexec_image_probe_default(image, buf, buf_len);
}

/**
 * setup_purgatory - initialize the purgatory's global variables
 * @image:              kexec image.
 * @slave_code:         Slave code for the purgatory.
 * @fdt:                Flattened device tree for the next kernel.
 * @kernel_load_addr:   Address where the kernel is loaded.
 * @fdt_load_addr:      Address where the flattened device tree is loaded.
 *
 * Return: 0 on success, or negative errno on error.
 */
int setup_purgatory(struct kimage *image, const void *slave_code,
                    const void *fdt, unsigned long kernel_load_addr,
                    unsigned long fdt_load_addr)
{
        unsigned int *slave_code_buf, master_entry;
        int ret;

        slave_code_buf = kmalloc(SLAVE_CODE_SIZE, GFP_KERNEL);
        if (!slave_code_buf)
                return -ENOMEM;

        /* Get the slave code from the new kernel and put it in purgatory. */
        ret = kexec_purgatory_get_set_symbol(image, "purgatory_start",
                                             slave_code_buf, SLAVE_CODE_SIZE,
                                             true);
        if (ret) {
                kfree(slave_code_buf);
                return ret;
        }

        master_entry = slave_code_buf[0];
        memcpy(slave_code_buf, slave_code, SLAVE_CODE_SIZE);
        slave_code_buf[0] = master_entry;
        ret = kexec_purgatory_get_set_symbol(image, "purgatory_start",
                                             slave_code_buf, SLAVE_CODE_SIZE,
                                             false);
        kfree(slave_code_buf);

        ret = kexec_purgatory_get_set_symbol(image, "kernel", &kernel_load_addr,
                                             sizeof(kernel_load_addr), false);
        if (ret)
                return ret;
        ret = kexec_purgatory_get_set_symbol(image, "dt_offset", &fdt_load_addr,
                                             sizeof(fdt_load_addr), false);
        if (ret)
                return ret;

        return 0;
}

/**
 * delete_fdt_mem_rsv - delete memory reservation with given address and size
 *
 * Return: 0 on success, or negative errno on error.
 */
int delete_fdt_mem_rsv(void *fdt, unsigned long start, unsigned long size)
{
        int i, ret, num_rsvs = fdt_num_mem_rsv(fdt);

        for (i = 0; i < num_rsvs; i++) {
                uint64_t rsv_start, rsv_size;

                ret = fdt_get_mem_rsv(fdt, i, &rsv_start, &rsv_size);
                if (ret) {
                        pr_err("Malformed device tree.\n");
                        return -EINVAL;
                }

                if (rsv_start == start && rsv_size == size) {
                        ret = fdt_del_mem_rsv(fdt, i);
                        if (ret) {
                                pr_err("Error deleting device tree reservation.\n");
                                return -EINVAL;
                        }

                        return 0;
                }
        }

        return -ENOENT;
}

/*
 * setup_new_fdt - modify /chosen and memory reservation for the next kernel
 * @image:              kexec image being loaded.
 * @fdt:                Flattened device tree for the next kernel.
 * @initrd_load_addr:   Address where the next initrd will be loaded.
 * @initrd_len:         Size of the next initrd, or 0 if there will be none.
 * @cmdline:            Command line for the next kernel, or NULL if there will
 *                      be none.
 *
 * Return: 0 on success, or negative errno on error.
 */
int setup_new_fdt(const struct kimage *image, void *fdt,
                  unsigned long initrd_load_addr, unsigned long initrd_len,
                  const char *cmdline)
{
        int ret, chosen_node;
        const void *prop;

        /* Remove memory reservation for the current device tree. */
        ret = delete_fdt_mem_rsv(fdt, __pa(initial_boot_params),
                                 fdt_totalsize(initial_boot_params));
        if (ret == 0)
                pr_debug("Removed old device tree reservation.\n");
        else if (ret != -ENOENT)
                return ret;

        chosen_node = fdt_path_offset(fdt, "/chosen");
        if (chosen_node == -FDT_ERR_NOTFOUND) {
                chosen_node = fdt_add_subnode(fdt, fdt_path_offset(fdt, "/"),
                                              "chosen");
                if (chosen_node < 0) {
                        pr_err("Error creating /chosen.\n");
                        return -EINVAL;
                }
        } else if (chosen_node < 0) {
                pr_err("Malformed device tree: error reading /chosen.\n");
                return -EINVAL;
        }

        /* Did we boot using an initrd? */
        prop = fdt_getprop(fdt, chosen_node, "linux,initrd-start", NULL);
        if (prop) {
                uint64_t tmp_start, tmp_end, tmp_size;

                tmp_start = fdt64_to_cpu(*((const fdt64_t *) prop));

                prop = fdt_getprop(fdt, chosen_node, "linux,initrd-end", NULL);
                if (!prop) {
                        pr_err("Malformed device tree.\n");
                        return -EINVAL;
                }
                tmp_end = fdt64_to_cpu(*((const fdt64_t *) prop));

                /*
                 * kexec reserves exact initrd size, while firmware may
                 * reserve a multiple of PAGE_SIZE, so check for both.
                 */
                tmp_size = tmp_end - tmp_start;
                ret = delete_fdt_mem_rsv(fdt, tmp_start, tmp_size);
                if (ret == -ENOENT)
                        ret = delete_fdt_mem_rsv(fdt, tmp_start,
                                                 round_up(tmp_size, PAGE_SIZE));
                if (ret == 0)
                        pr_debug("Removed old initrd reservation.\n");
                else if (ret != -ENOENT)
                        return ret;

                /* If there's no new initrd, delete the old initrd's info. */
                if (initrd_len == 0) {
                        ret = fdt_delprop(fdt, chosen_node,
                                          "linux,initrd-start");
                        if (ret) {
                                pr_err("Error deleting linux,initrd-start.\n");
                                return -EINVAL;
                        }

                        ret = fdt_delprop(fdt, chosen_node, "linux,initrd-end");
                        if (ret) {
                                pr_err("Error deleting linux,initrd-end.\n");
                                return -EINVAL;
                        }
                }
        }

        if (initrd_len) {
                ret = fdt_setprop_u64(fdt, chosen_node,
                                      "linux,initrd-start",
                                      initrd_load_addr);
                if (ret < 0)
                        goto err;

                /* initrd-end is the first address after the initrd image. */
                ret = fdt_setprop_u64(fdt, chosen_node, "linux,initrd-end",
                                      initrd_load_addr + initrd_len);
                if (ret < 0)
                        goto err;

                ret = fdt_add_mem_rsv(fdt, initrd_load_addr, initrd_len);
                if (ret) {
                        pr_err("Error reserving initrd memory: %s\n",
                               fdt_strerror(ret));
                        return -EINVAL;
                }
        }

        if (cmdline != NULL) {
                ret = fdt_setprop_string(fdt, chosen_node, "bootargs", cmdline);
                if (ret < 0)
                        goto err;
        } else {
                ret = fdt_delprop(fdt, chosen_node, "bootargs");
                if (ret && ret != -FDT_ERR_NOTFOUND) {
                        pr_err("Error deleting bootargs.\n");
                        return -EINVAL;
                }
        }

        ret = setup_ima_buffer(image, fdt, chosen_node);
        if (ret) {
                pr_err("Error setting up the new device tree.\n");
                return ret;
        }

        ret = fdt_setprop(fdt, chosen_node, "linux,booted-from-kexec", NULL, 0);
        if (ret)
                goto err;

        return 0;

err:
        pr_err("Error setting up the new device tree.\n");
        return -EINVAL;
}