// SPDX-License-Identifier: GPL-2.0
/*
 * Helper functions used by the EFI stub on multiple
 * architectures. This should be #included by the EFI stub
 * implementation files.
 *
 * Copyright 2011 Intel Corporation; author Matt Fleming
 */

#include <linux/efi.h>
#include <asm/efi.h>

#include "efistub.h"

#define MAX_FILENAME_SIZE       256

/*
 * Some firmware implementations have problems reading files in one go.
 * A read chunk size of 1MB seems to work for most platforms.
 *
 * Unfortunately, reading files in chunks triggers *other* bugs on some
 * platforms, so we provide a way to disable this workaround, which can
 * be done by passing "efi=nochunk" on the EFI boot stub command line.
 *
 * If you experience issues with initrd images being corrupt it's worth
 * trying efi=nochunk, but chunking is enabled by default on x86 because
 * there are far more machines that require the workaround than those that
 * break with it enabled.
 */
#define EFI_READ_CHUNK_SIZE     SZ_1M

struct finfo {
        efi_file_info_t info;
        efi_char16_t    filename[MAX_FILENAME_SIZE];
};

static efi_status_t efi_open_file(efi_file_protocol_t *volume,
                                  struct finfo *fi,
                                  efi_file_protocol_t **handle,
                                  unsigned long *file_size)
{
        efi_guid_t info_guid = EFI_FILE_INFO_ID;
        efi_file_protocol_t *fh;
        unsigned long info_sz;
        efi_status_t status;

        status = volume->open(volume, &fh, fi->filename, EFI_FILE_MODE_READ, 0);
        if (status != EFI_SUCCESS) {
                efi_err("Failed to open file: %ls\n", fi->filename);
                return status;
        }

        info_sz = sizeof(struct finfo);
        status = fh->get_info(fh, &info_guid, &info_sz, fi);
        if (status != EFI_SUCCESS) {
                efi_err("Failed to get file info\n");
                fh->close(fh);
                return status;
        }

        *handle = fh;
        *file_size = fi->info.file_size;
        return EFI_SUCCESS;
}

static efi_status_t efi_open_volume(efi_loaded_image_t *image,
                                    efi_file_protocol_t **fh)
{
        efi_guid_t fs_proto = EFI_FILE_SYSTEM_GUID;
        efi_simple_file_system_protocol_t *io;
        efi_status_t status;

        status = efi_bs_call(handle_protocol, image->device_handle, &fs_proto,
                             (void **)&io);
        if (status != EFI_SUCCESS) {
                efi_err("Failed to handle fs_proto\n");
                return status;
        }

        status = io->open_volume(io, fh);
        if (status != EFI_SUCCESS)
                efi_err("Failed to open volume\n");

        return status;
}

static int find_file_option(const efi_char16_t *cmdline, int cmdline_len,
                            const efi_char16_t *prefix, int prefix_size,
                            efi_char16_t *result, int result_len)
{
        int prefix_len = prefix_size / 2;
        bool found = false;
        int i;

        for (i = prefix_len; i < cmdline_len; i++) {
                if (!memcmp(&cmdline[i - prefix_len], prefix, prefix_size)) {
                        found = true;
                        break;
                }
        }

        if (!found)
                return 0;

        /* Skip any leading slashes */
        while (i < cmdline_len && (cmdline[i] == L'/' || cmdline[i] == L'\\'))
                i++;

        while (--result_len > 0 && i < cmdline_len) {
                efi_char16_t c = cmdline[i++];

                if (c == L'\0' || c == L'\n' || c == L' ')
                        break;
                else if (c == L'/')
                        /* Replace UNIX dir separators with EFI standard ones */
                        *result++ = L'\\';
                else
                        *result++ = c;
        }
        *result = L'\0';
        return i;
}

/*
 * Check the cmdline for a LILO-style file= arguments.
 *
 * We only support loading a file from the same filesystem as
 * the kernel image.
 */
efi_status_t handle_cmdline_files(efi_loaded_image_t *image,
                                  const efi_char16_t *optstr,
                                  int optstr_size,
                                  unsigned long soft_limit,
                                  unsigned long hard_limit,
                                  unsigned long *load_addr,
                                  unsigned long *load_size)
{
        const efi_char16_t *cmdline = image->load_options;
        int cmdline_len = image->load_options_size;
        unsigned long efi_chunk_size = ULONG_MAX;
        efi_file_protocol_t *volume = NULL;
        efi_file_protocol_t *file;
        unsigned long alloc_addr;
        unsigned long alloc_size;
        efi_status_t status;
        int offset;

        if (!load_addr || !load_size)
                return EFI_INVALID_PARAMETER;

        efi_apply_loadoptions_quirk((const void **)&cmdline, &cmdline_len);
        cmdline_len /= sizeof(*cmdline);

        if (IS_ENABLED(CONFIG_X86) && !efi_nochunk)
                efi_chunk_size = EFI_READ_CHUNK_SIZE;

        alloc_addr = alloc_size = 0;
        do {
                struct finfo fi;
                unsigned long size;
                void *addr;

                offset = find_file_option(cmdline, cmdline_len,
                                          optstr, optstr_size,
                                          fi.filename, ARRAY_SIZE(fi.filename));

                if (!offset)
                        break;

                cmdline += offset;
                cmdline_len -= offset;

                if (!volume) {
                        status = efi_open_volume(image, &volume);
                        if (status != EFI_SUCCESS)
                                return status;
                }

                status = efi_open_file(volume, &fi, &file, &size);
                if (status != EFI_SUCCESS)
                        goto err_close_volume;

                /*
                 * Check whether the existing allocation can contain the next
                 * file. This condition will also trigger naturally during the
                 * first (and typically only) iteration of the loop, given that
                 * alloc_size == 0 in that case.
                 */
                if (round_up(alloc_size + size, EFI_ALLOC_ALIGN) >
                    round_up(alloc_size, EFI_ALLOC_ALIGN)) {
                        unsigned long old_addr = alloc_addr;

                        status = EFI_OUT_OF_RESOURCES;
                        if (soft_limit < hard_limit)
                                status = efi_allocate_pages(alloc_size + size,
                                                            &alloc_addr,
                                                            soft_limit);
                        if (status == EFI_OUT_OF_RESOURCES)
                                status = efi_allocate_pages(alloc_size + size,
                                                            &alloc_addr,
                                                            hard_limit);
                        if (status != EFI_SUCCESS) {
                                efi_err("Failed to allocate memory for files\n");
                                goto err_close_file;
                        }

                        if (old_addr != 0) {
                                /*
                                 * This is not the first time we've gone
                                 * around this loop, and so we are loading
                                 * multiple files that need to be concatenated
                                 * and returned in a single buffer.
                                 */
                                memcpy((void *)alloc_addr, (void *)old_addr, alloc_size);
                                efi_free(alloc_size, old_addr);
                        }
                }

                addr = (void *)alloc_addr + alloc_size;
                alloc_size += size;

                while (size) {
                        unsigned long chunksize = min(size, efi_chunk_size);

                        status = file->read(file, &chunksize, addr);
                        if (status != EFI_SUCCESS) {
                                efi_err("Failed to read file\n");
                                goto err_close_file;
                        }
                        addr += chunksize;
                        size -= chunksize;
                }
                file->close(file);
        } while (offset > 0);

        *load_addr = alloc_addr;
        *load_size = alloc_size;

        if (volume)
                volume->close(volume);
        return EFI_SUCCESS;

err_close_file:
        file->close(file);

err_close_volume:
        volume->close(volume);
        efi_free(alloc_size, alloc_addr);
        return status;
}