1 /* 2 * QEMU PC System Firmware (OVMF specific) 3 * 4 * Copyright (c) 2003-2004 Fabrice Bellard 5 * Copyright (c) 2011-2012 Intel Corporation 6 * 7 * Permission is hereby granted, free of charge, to any person obtaining a copy 8 * of this software and associated documentation files (the "Software"), to deal 9 * in the Software without restriction, including without limitation the rights 10 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell 11 * copies of the Software, and to permit persons to whom the Software is 12 * furnished to do so, subject to the following conditions: 13 * 14 * The above copyright notice and this permission notice shall be included in 15 * all copies or substantial portions of the Software. 16 * 17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 18 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 19 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL 20 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 21 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 22 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN 23 * THE SOFTWARE. 24 */ 25 26 #include "qemu/osdep.h" 27 #include "qemu/error-report.h" 28 #include "hw/i386/pc.h" 29 #include "cpu.h" 30 31 #define OVMF_TABLE_FOOTER_GUID "96b582de-1fb2-45f7-baea-a366c55a082d" 32 33 static const int bytes_after_table_footer = 32; 34 35 static bool ovmf_flash_parsed; 36 static uint8_t *ovmf_table; 37 static int ovmf_table_len; 38 39 void pc_system_parse_ovmf_flash(uint8_t *flash_ptr, size_t flash_size) 40 { 41 uint8_t *ptr; 42 QemuUUID guid; 43 int tot_len; 44 45 /* should only be called once */ 46 if (ovmf_flash_parsed) { 47 return; 48 } 49 50 ovmf_flash_parsed = true; 51 52 if (flash_size < TARGET_PAGE_SIZE) { 53 return; 54 } 55 56 /* 57 * if this is OVMF there will be a table footer 58 * guid 48 bytes before the end of the flash file 59 * (= 32 bytes after the table + 16 bytes the GUID itself). 60 * If it's not found, silently abort the flash parsing. 61 */ 62 qemu_uuid_parse(OVMF_TABLE_FOOTER_GUID, &guid); 63 guid = qemu_uuid_bswap(guid); /* guids are LE */ 64 ptr = flash_ptr + flash_size - (bytes_after_table_footer + sizeof(guid)); 65 if (!qemu_uuid_is_equal((QemuUUID *)ptr, &guid)) { 66 return; 67 } 68 69 /* if found, just before is two byte table length */ 70 ptr -= sizeof(uint16_t); 71 tot_len = le16_to_cpu(*(uint16_t *)ptr) - sizeof(guid) - sizeof(uint16_t); 72 73 if (tot_len < 0 || tot_len > (ptr - flash_ptr)) { 74 error_report("OVMF table has invalid size %d", tot_len); 75 return; 76 } 77 78 if (tot_len == 0) { 79 /* no entries in the OVMF table */ 80 return; 81 } 82 83 ovmf_table = g_malloc(tot_len); 84 ovmf_table_len = tot_len; 85 86 /* 87 * ptr is the foot of the table, so copy it all to the newly 88 * allocated ovmf_table and then set the ovmf_table pointer 89 * to the table foot 90 */ 91 memcpy(ovmf_table, ptr - tot_len, tot_len); 92 ovmf_table += tot_len; 93 } 94 95 /** 96 * pc_system_ovmf_table_find - Find the data associated with an entry in OVMF's 97 * reset vector GUIDed table. 98 * 99 * @entry: GUID string of the entry to lookup 100 * @data: Filled with a pointer to the entry's value (if not NULL) 101 * @data_len: Filled with the length of the entry's value (if not NULL). Pass 102 * NULL here if the length of data is known. 103 * 104 * Return: true if the entry was found in the OVMF table; false otherwise. 105 */ 106 bool pc_system_ovmf_table_find(const char *entry, uint8_t **data, 107 int *data_len) 108 { 109 uint8_t *ptr = ovmf_table; 110 int tot_len = ovmf_table_len; 111 QemuUUID entry_guid; 112 113 assert(ovmf_flash_parsed); 114 115 if (qemu_uuid_parse(entry, &entry_guid) < 0) { 116 return false; 117 } 118 119 if (!ptr) { 120 return false; 121 } 122 123 entry_guid = qemu_uuid_bswap(entry_guid); /* guids are LE */ 124 while (tot_len >= sizeof(QemuUUID) + sizeof(uint16_t)) { 125 int len; 126 QemuUUID *guid; 127 128 /* 129 * The data structure is 130 * arbitrary length data 131 * 2 byte length of entire entry 132 * 16 byte guid 133 */ 134 guid = (QemuUUID *)(ptr - sizeof(QemuUUID)); 135 len = le16_to_cpu(*(uint16_t *)(ptr - sizeof(QemuUUID) - 136 sizeof(uint16_t))); 137 138 /* 139 * just in case the table is corrupt, wouldn't want to spin in 140 * the zero case 141 */ 142 if (len < sizeof(QemuUUID) + sizeof(uint16_t)) { 143 return false; 144 } else if (len > tot_len) { 145 return false; 146 } 147 148 ptr -= len; 149 tot_len -= len; 150 if (qemu_uuid_is_equal(guid, &entry_guid)) { 151 if (data) { 152 *data = ptr; 153 } 154 if (data_len) { 155 *data_len = len - sizeof(QemuUUID) - sizeof(uint16_t); 156 } 157 return true; 158 } 159 } 160 return false; 161 } 162