// SPDX-License-Identifier: GPL-2.0
/*
 * Kexec image loader

 * Copyright (C) 2018 Linaro Limited
 * Author: AKASHI Takahiro <takahiro.akashi@linaro.org>
 */

#define pr_fmt(fmt)     "kexec_file(Image): " fmt

#include <linux/err.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/kexec.h>
#include <linux/pe.h>
#include <linux/string.h>
#include <asm/byteorder.h>
#include <asm/cpufeature.h>
#include <asm/image.h>
#include <asm/memory.h>

static int image_probe(const char *kernel_buf, unsigned long kernel_len)
{
        const struct arm64_image_header *h =
                (const struct arm64_image_header *)(kernel_buf);

        if (!h || (kernel_len < sizeof(*h)))
                return -EINVAL;

        if (memcmp(&h->magic, ARM64_IMAGE_MAGIC, sizeof(h->magic)))
                return -EINVAL;

        return 0;
}

static void *image_load(struct kimage *image,
                                char *kernel, unsigned long kernel_len,
                                char *initrd, unsigned long initrd_len,
                                char *cmdline, unsigned long cmdline_len)
{
        struct arm64_image_header *h;
        u64 flags, value;
        bool be_image, be_kernel;
        struct kexec_buf kbuf = {};
        unsigned long text_offset, kernel_segment_number;
        struct kexec_segment *kernel_segment;
        int ret;

        /*
         * We require a kernel with an unambiguous Image header. Per
         * Documentation/arch/arm64/booting.rst, this is the case when image_size
         * is non-zero (practically speaking, since v3.17).
         */
        h = (struct arm64_image_header *)kernel;
        if (!h->image_size)
                return ERR_PTR(-EINVAL);

        /* Check cpu features */
        flags = le64_to_cpu(h->flags);
        be_image = arm64_image_flag_field(flags, ARM64_IMAGE_FLAG_BE);
        be_kernel = IS_ENABLED(CONFIG_CPU_BIG_ENDIAN);
        if ((be_image != be_kernel) && !system_supports_mixed_endian())
                return ERR_PTR(-EINVAL);

        value = arm64_image_flag_field(flags, ARM64_IMAGE_FLAG_PAGE_SIZE);
        if (((value == ARM64_IMAGE_FLAG_PAGE_SIZE_4K) &&
                        !system_supports_4kb_granule()) ||
            ((value == ARM64_IMAGE_FLAG_PAGE_SIZE_64K) &&
                        !system_supports_64kb_granule()) ||
            ((value == ARM64_IMAGE_FLAG_PAGE_SIZE_16K) &&
                        !system_supports_16kb_granule()))
                return ERR_PTR(-EINVAL);

        /* Load the kernel */
        kbuf.image = image;
        kbuf.buf_min = 0;
        kbuf.buf_max = ULONG_MAX;
        kbuf.top_down = false;

        kbuf.buffer = kernel;
        kbuf.bufsz = kernel_len;
        kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
        kbuf.memsz = le64_to_cpu(h->image_size);
        text_offset = le64_to_cpu(h->text_offset);
        kbuf.buf_align = MIN_KIMG_ALIGN;

        /* Adjust kernel segment with TEXT_OFFSET */
        kbuf.memsz += text_offset;

        kernel_segment_number = image->nr_segments;

        /*
         * The location of the kernel segment may make it impossible to satisfy
         * the other segment requirements, so we try repeatedly to find a
         * location that will work.
         */
        while ((ret = kexec_add_buffer(&kbuf)) == 0) {
                /* Try to load additional data */
                kernel_segment = &image->segment[kernel_segment_number];
                ret = load_other_segments(image, kernel_segment->mem,
                                          kernel_segment->memsz, initrd,
                                          initrd_len, cmdline);
                if (!ret)
                        break;

                /*
                 * We couldn't find space for the other segments; erase the
                 * kernel segment and try the next available hole.
                 */
                image->nr_segments -= 1;
                kbuf.buf_min = kernel_segment->mem + kernel_segment->memsz;
                kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
        }

        if (ret) {
                pr_err("Could not find any suitable kernel location!");
                return ERR_PTR(ret);
        }

        kernel_segment = &image->segment[kernel_segment_number];
        kernel_segment->mem += text_offset;
        kernel_segment->memsz -= text_offset;
        image->start = kernel_segment->mem;

        kexec_dprintk("Loaded kernel at 0x%lx bufsz=0x%lx memsz=0x%lx\n",
                      kernel_segment->mem, kbuf.bufsz,
                      kernel_segment->memsz);

        return NULL;
}

const struct kexec_file_ops kexec_image_ops = {
        .probe = image_probe,
        .load = image_load,
#ifdef CONFIG_KEXEC_IMAGE_VERIFY_SIG
        .verify_sig = kexec_kernel_verify_pe_sig,
#endif
};