128 lines
3.6 KiB
C
128 lines
3.6 KiB
C
/*
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* Copyright (C) 2021 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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//note: this file is copy form /andriod12/bootable/libbootloader
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#include "libxbc.h"
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#define BOOTCONFIG_MAGIC "#BOOTCONFIG\n"
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#define BOOTCONFIG_MAGIC_SIZE 12
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#define BOOTCONFIG_SIZE_SIZE 4
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#define BOOTCONFIG_CHECKSUM_SIZE 4
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#define BOOTCONFIG_TRAILER_SIZE \
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BOOTCONFIG_MAGIC_SIZE + BOOTCONFIG_SIZE_SIZE + BOOTCONFIG_CHECKSUM_SIZE
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/*
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* Simple checksum for a buffer.
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*
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* @param addr pointer to the start of the buffer.
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* @param size size of the buffer in bytes.
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* @return check sum result.
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*/
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static uint32_t checksum(const unsigned char *const buffer, uint32_t size)
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{
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uint32_t sum = 0;
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for (uint32_t i = 0; i < size; i++) {
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sum += buffer[i];
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}
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return sum;
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}
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/*
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* Check if the bootconfig trailer is present within the bootconfig section.
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*
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* @param bootconfig_end_addr address of the end of the bootconfig section. If
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* the trailer is present, it will be directly preceding this address.
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* @return true if the trailer is present, false if not.
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* note: this file is copy form /andriod12/bootable/libbootloader
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*/
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int isTrailerPresent(unsigned long bootconfig_end_addr)
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{
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return !strncmp(
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(const char *)(bootconfig_end_addr - BOOTCONFIG_MAGIC_SIZE),
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BOOTCONFIG_MAGIC, BOOTCONFIG_MAGIC_SIZE);
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}
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/*
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* Add a string of boot config parameters to memory appended by the trailer.
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* note: this file is copy form /andriod12/bootable/libbootloader
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*/
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int32_t addBootConfigParameters(char *params, uint32_t params_size,
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unsigned long bootconfig_start_addr,
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uint32_t bootconfig_size)
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{
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if (!params || !bootconfig_start_addr) {
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return -1;
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}
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if (params_size == 0) {
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return 0;
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}
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int32_t applied_bytes = 0;
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int32_t new_size = 0;
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unsigned long end = bootconfig_start_addr + bootconfig_size;
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if (isTrailerPresent(end)) {
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end -= BOOTCONFIG_TRAILER_SIZE;
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applied_bytes -= BOOTCONFIG_TRAILER_SIZE;
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memcpy(&new_size, (void *)end, BOOTCONFIG_SIZE_SIZE);
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} else {
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new_size = bootconfig_size;
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}
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// params
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memcpy((void *)end, params, params_size);
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applied_bytes += params_size;
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applied_bytes += addBootConfigTrailer(bootconfig_start_addr,
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bootconfig_size + applied_bytes);
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return applied_bytes;
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}
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/*
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* Add boot config trailer.
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* note: this file is copy form /andriod12/bootable/libbootloader
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*/
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int32_t addBootConfigTrailer(unsigned long bootconfig_start_addr,
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unsigned long bootconfig_size)
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{
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if (!bootconfig_start_addr) {
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return -1;
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}
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if (bootconfig_size == 0) {
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return 0;
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}
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unsigned long end = bootconfig_start_addr + bootconfig_size;
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if (isTrailerPresent(end)) {
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// no need to overwrite the current trailers
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return 0;
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}
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// size
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memcpy((void *)(end), &bootconfig_size, BOOTCONFIG_SIZE_SIZE);
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// checksum
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uint32_t sum = checksum((unsigned char *)bootconfig_start_addr,
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bootconfig_size);
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memcpy((void *)(end + BOOTCONFIG_SIZE_SIZE), &sum,
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BOOTCONFIG_CHECKSUM_SIZE);
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// magic
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memcpy((void *)(end + BOOTCONFIG_SIZE_SIZE + BOOTCONFIG_CHECKSUM_SIZE),
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BOOTCONFIG_MAGIC, BOOTCONFIG_MAGIC_SIZE);
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return BOOTCONFIG_TRAILER_SIZE;
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}
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