qemu

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/* Dynamic linker/loader of ACPI tables
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 *
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 * Copyright (C) 2013 Red Hat Inc
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 *
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 * Author: Michael S. Tsirkin <mst@redhat.com>
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 *
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 * This program is free software; you can redistribute it and/or modify
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 * it under the terms of the GNU General Public License as published by
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 * the Free Software Foundation; either version 2 of the License, or
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 * (at your option) any later version.
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 * This program is distributed in the hope that it will be useful,
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 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
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 * GNU General Public License for more details.
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 * You should have received a copy of the GNU General Public License along
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 * with this program; if not, see <http://www.gnu.org/licenses/>.
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 */
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#include "qemu/osdep.h"
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#include "hw/acpi/bios-linker-loader.h"
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#include "hw/nvram/fw_cfg.h"
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#include "qemu/bswap.h"
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/*
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 * Linker/loader is a paravirtualized interface that passes commands to guest.
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 * The commands can be used to request guest to
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 * - allocate memory chunks and initialize them from QEMU FW CFG files
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 * - link allocated chunks by storing pointer to one chunk into another
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 * - calculate ACPI checksum of part of the chunk and store into same chunk
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 */
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#define BIOS_LINKER_LOADER_FILESZ FW_CFG_MAX_FILE_PATH
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struct BiosLinkerLoaderEntry {
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    uint32_t command;
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    union {
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        /*
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         * COMMAND_ALLOCATE - allocate a table from @alloc.file
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         * subject to @alloc.align alignment (must be power of 2)
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         * and @alloc.zone (can be HIGH or FSEG) requirements.
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         *
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         * Must appear exactly once for each file, and before
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         * this file is referenced by any other command.
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         */
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        struct {
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            char file[BIOS_LINKER_LOADER_FILESZ];
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            uint32_t align;
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            uint8_t zone;
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        } alloc;
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        /*
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         * COMMAND_ADD_POINTER - patch the table (originating from
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         * @dest_file) at @pointer.offset, by adding a pointer to the table
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         * originating from @src_file. 1,2,4 or 8 byte unsigned
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         * addition is used depending on @pointer.size.
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         */
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        struct {
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            char dest_file[BIOS_LINKER_LOADER_FILESZ];
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            char src_file[BIOS_LINKER_LOADER_FILESZ];
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            uint32_t offset;
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            uint8_t size;
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        } pointer;
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        /*
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         * COMMAND_ADD_CHECKSUM - calculate checksum of the range specified by
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         * @cksum_start and @cksum_length fields,
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         * and then add the value at @cksum.offset.
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         * Checksum simply sums -X for each byte X in the range
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         * using 8-bit math.
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         */
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        struct {
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            char file[BIOS_LINKER_LOADER_FILESZ];
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            uint32_t offset;
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            uint32_t start;
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            uint32_t length;
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        } cksum;
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        /*
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         * COMMAND_WRITE_POINTER - write the fw_cfg file (originating from
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         * @dest_file) at @wr_pointer.offset, by adding a pointer to
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         * @src_offset within the table originating from @src_file.
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         * 1,2,4 or 8 byte unsigned addition is used depending on
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         * @wr_pointer.size.
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         */
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        struct {
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            char dest_file[BIOS_LINKER_LOADER_FILESZ];
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            char src_file[BIOS_LINKER_LOADER_FILESZ];
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            uint32_t dst_offset;
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            uint32_t src_offset;
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            uint8_t size;
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        } wr_pointer;
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        /* padding */
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        char pad[124];
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    };
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} QEMU_PACKED;
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typedef struct BiosLinkerLoaderEntry BiosLinkerLoaderEntry;
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enum {
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    BIOS_LINKER_LOADER_COMMAND_ALLOCATE          = 0x1,
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    BIOS_LINKER_LOADER_COMMAND_ADD_POINTER       = 0x2,
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    BIOS_LINKER_LOADER_COMMAND_ADD_CHECKSUM      = 0x3,
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    BIOS_LINKER_LOADER_COMMAND_WRITE_POINTER     = 0x4,
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};
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enum {
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    BIOS_LINKER_LOADER_ALLOC_ZONE_HIGH = 0x1,
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    BIOS_LINKER_LOADER_ALLOC_ZONE_FSEG = 0x2,
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};
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/*
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 * BiosLinkerFileEntry:
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 *
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 * An internal type used for book-keeping file entries
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 */
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typedef struct BiosLinkerFileEntry {
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    char *name; /* file name */
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    GArray *blob; /* data accosiated with @name */
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} BiosLinkerFileEntry;
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/*
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 * bios_linker_loader_init: allocate a new linker object instance.
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 *
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 * After initialization, linker commands can be added, and will
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 * be stored in the linker.cmd_blob array.
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 */
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BIOSLinker *bios_linker_loader_init(void)
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{
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    BIOSLinker *linker = g_new(BIOSLinker, 1);
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    linker->cmd_blob = g_array_new(false, true /* clear */, 1);
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    linker->file_list = g_array_new(false, true /* clear */,
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                                    sizeof(BiosLinkerFileEntry));
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    return linker;
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}
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/* Free linker wrapper */
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void bios_linker_loader_cleanup(BIOSLinker *linker)
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{
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    int i;
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    BiosLinkerFileEntry *entry;
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    g_array_free(linker->cmd_blob, true);
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    for (i = 0; i < linker->file_list->len; i++) {
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        entry = &g_array_index(linker->file_list, BiosLinkerFileEntry, i);
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        g_free(entry->name);
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    }
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    g_array_free(linker->file_list, true);
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    g_free(linker);
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}
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static const BiosLinkerFileEntry *
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bios_linker_find_file(const BIOSLinker *linker, const char *name)
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{
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    int i;
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    BiosLinkerFileEntry *entry;
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    for (i = 0; i < linker->file_list->len; i++) {
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        entry = &g_array_index(linker->file_list, BiosLinkerFileEntry, i);
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        if (!strcmp(entry->name, name)) {
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            return entry;
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        }
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    }
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    return NULL;
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}
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/*
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 * board code must realize fw_cfg first, as a fixed device, before
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 * another device realize function call bios_linker_loader_can_write_pointer()
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 */
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bool bios_linker_loader_can_write_pointer(void)
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{
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    FWCfgState *fw_cfg = fw_cfg_find();
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    return fw_cfg && fw_cfg_dma_enabled(fw_cfg);
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}
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/*
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 * bios_linker_loader_alloc: ask guest to load file into guest memory.
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 *
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 * @linker: linker object instance
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 * @file_name: name of the file blob to be loaded
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 * @file_blob: pointer to blob corresponding to @file_name
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 * @alloc_align: required minimal alignment in bytes. Must be a power of 2.
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 * @alloc_fseg: request allocation in FSEG zone (useful for the RSDP ACPI table)
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 *
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 * Note: this command must precede any other linker command using this file.
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 */
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void bios_linker_loader_alloc(BIOSLinker *linker,
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                              const char *file_name,
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                              GArray *file_blob,
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                              uint32_t alloc_align,
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                              bool alloc_fseg)
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{
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    BiosLinkerLoaderEntry entry;
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    BiosLinkerFileEntry file = { g_strdup(file_name), file_blob};
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    assert(!(alloc_align & (alloc_align - 1)));
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    assert(!bios_linker_find_file(linker, file_name));
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    g_array_append_val(linker->file_list, file);
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    memset(&entry, 0, sizeof entry);
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    strncpy(entry.alloc.file, file_name, sizeof entry.alloc.file - 1);
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    entry.command = cpu_to_le32(BIOS_LINKER_LOADER_COMMAND_ALLOCATE);
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    entry.alloc.align = cpu_to_le32(alloc_align);
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    entry.alloc.zone = alloc_fseg ? BIOS_LINKER_LOADER_ALLOC_ZONE_FSEG :
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                                    BIOS_LINKER_LOADER_ALLOC_ZONE_HIGH;
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    /* Alloc entries must come first, so prepend them */
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    g_array_prepend_vals(linker->cmd_blob, &entry, sizeof entry);
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}
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/*
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 * bios_linker_loader_add_checksum: ask guest to add checksum of ACPI
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 * table in the specified file at the specified offset.
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 *
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 * Checksum calculation simply sums -X for each byte X in the range
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 * using 8-bit math (i.e. ACPI checksum).
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 *
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 * @linker: linker object instance
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 * @file: file that includes the checksum to be calculated
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 *        and the data to be checksummed
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 * @start_offset, @size: range of data in the file to checksum,
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 *                       relative to the start of file blob
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 * @checksum_offset: location of the checksum to be patched within file blob,
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 *                   relative to the start of file blob
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 */
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void bios_linker_loader_add_checksum(BIOSLinker *linker, const char *file_name,
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                                     unsigned start_offset, unsigned size,
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                                     unsigned checksum_offset)
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{
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    BiosLinkerLoaderEntry entry;
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    const BiosLinkerFileEntry *file = bios_linker_find_file(linker, file_name);
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    assert(file);
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    assert(start_offset < file->blob->len);
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    assert(start_offset + size <= file->blob->len);
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    assert(checksum_offset >= start_offset);
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    assert(checksum_offset + 1 <= start_offset + size);
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    *(file->blob->data + checksum_offset) = 0;
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    memset(&entry, 0, sizeof entry);
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    strncpy(entry.cksum.file, file_name, sizeof entry.cksum.file - 1);
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    entry.command = cpu_to_le32(BIOS_LINKER_LOADER_COMMAND_ADD_CHECKSUM);
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    entry.cksum.offset = cpu_to_le32(checksum_offset);
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    entry.cksum.start = cpu_to_le32(start_offset);
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    entry.cksum.length = cpu_to_le32(size);
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    g_array_append_vals(linker->cmd_blob, &entry, sizeof entry);
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}
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/*
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 * bios_linker_loader_add_pointer: ask guest to patch address in
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 * destination file with a pointer to source file
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 *
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 * @linker: linker object instance
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 * @dest_file: destination file that must be changed
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 * @dst_patched_offset: location within destination file blob to be patched
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 *                      with the pointer to @src_file+@src_offset (i.e. source
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 *                      blob allocated in guest memory + @src_offset), in bytes
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 * @dst_patched_offset_size: size of the pointer to be patched
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 *                      at @dst_patched_offset in @dest_file blob, in bytes
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 * @src_file: source file who's address must be taken
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 * @src_offset: location within source file blob to which
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 *              @dest_file+@dst_patched_offset will point to after
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 *              firmware's executed ADD_POINTER command
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 */
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void bios_linker_loader_add_pointer(BIOSLinker *linker,
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                                    const char *dest_file,
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                                    uint32_t dst_patched_offset,
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                                    uint8_t dst_patched_size,
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                                    const char *src_file,
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                                    uint32_t src_offset)
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{
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    uint64_t le_src_offset;
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    BiosLinkerLoaderEntry entry;
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    const BiosLinkerFileEntry *dst_file =
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        bios_linker_find_file(linker, dest_file);
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    const BiosLinkerFileEntry *source_file =
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        bios_linker_find_file(linker, src_file);
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    assert(dst_file);
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    assert(source_file);
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    assert(dst_patched_offset < dst_file->blob->len);
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    assert(dst_patched_offset + dst_patched_size <= dst_file->blob->len);
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    assert(src_offset < source_file->blob->len);
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    memset(&entry, 0, sizeof entry);
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    strncpy(entry.pointer.dest_file, dest_file,
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            sizeof entry.pointer.dest_file - 1);
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    strncpy(entry.pointer.src_file, src_file,
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            sizeof entry.pointer.src_file - 1);
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    entry.command = cpu_to_le32(BIOS_LINKER_LOADER_COMMAND_ADD_POINTER);
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    entry.pointer.offset = cpu_to_le32(dst_patched_offset);
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    entry.pointer.size = dst_patched_size;
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    assert(dst_patched_size == 1 || dst_patched_size == 2 ||
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           dst_patched_size == 4 || dst_patched_size == 8);
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    le_src_offset = cpu_to_le64(src_offset);
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    memcpy(dst_file->blob->data + dst_patched_offset,
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           &le_src_offset, dst_patched_size);
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    g_array_append_vals(linker->cmd_blob, &entry, sizeof entry);
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}
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/*
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 * bios_linker_loader_write_pointer: ask guest to write a pointer to the
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 * source file into the destination file, and write it back to QEMU via
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 * fw_cfg DMA.
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 *
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 * @linker: linker object instance
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 * @dest_file: destination file that must be written
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 * @dst_patched_offset: location within destination file blob to be patched
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 *                      with the pointer to @src_file, in bytes
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 * @dst_patched_offset_size: size of the pointer to be patched
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 *                      at @dst_patched_offset in @dest_file blob, in bytes
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 * @src_file: source file who's address must be taken
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 * @src_offset: location within source file blob to which
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 *              @dest_file+@dst_patched_offset will point to after
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 *              firmware's executed WRITE_POINTER command
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 */
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void bios_linker_loader_write_pointer(BIOSLinker *linker,
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                                    const char *dest_file,
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                                    uint32_t dst_patched_offset,
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                                    uint8_t dst_patched_size,
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                                    const char *src_file,
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                                    uint32_t src_offset)
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{
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    BiosLinkerLoaderEntry entry;
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    const BiosLinkerFileEntry *source_file =
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        bios_linker_find_file(linker, src_file);
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    assert(source_file);
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    assert(src_offset < source_file->blob->len);
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    memset(&entry, 0, sizeof entry);
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    strncpy(entry.wr_pointer.dest_file, dest_file,
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            sizeof entry.wr_pointer.dest_file - 1);
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    strncpy(entry.wr_pointer.src_file, src_file,
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            sizeof entry.wr_pointer.src_file - 1);
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    entry.command = cpu_to_le32(BIOS_LINKER_LOADER_COMMAND_WRITE_POINTER);
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    entry.wr_pointer.dst_offset = cpu_to_le32(dst_patched_offset);
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    entry.wr_pointer.src_offset = cpu_to_le32(src_offset);
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    entry.wr_pointer.size = dst_patched_size;
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    assert(dst_patched_size == 1 || dst_patched_size == 2 ||
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           dst_patched_size == 4 || dst_patched_size == 8);
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    g_array_append_vals(linker->cmd_blob, &entry, sizeof entry);
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}
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