144 lines
3.6 KiB
C
144 lines
3.6 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* Wrapper around the kernel's pre-boot decompression library.
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*
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* Copyright (C) IBM Corporation 2016.
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*/
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#include "elf.h"
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#include "page.h"
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#include "string.h"
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#include "stdio.h"
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#include "ops.h"
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#include "reg.h"
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#include "types.h"
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/*
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* The decompressor_*.c files play #ifdef games so they can be used in both
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* pre-boot and regular kernel code. We need these definitions to make the
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* includes work.
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*/
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#define STATIC static
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#define INIT
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/*
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* The build process will copy the required zlib source files and headers
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* out of lib/ and "fix" the includes so they do not pull in other kernel
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* headers.
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*/
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#ifdef CONFIG_KERNEL_GZIP
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# include "decompress_inflate.c"
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#endif
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#ifdef CONFIG_KERNEL_XZ
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# include "xz_config.h"
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# include "../../../lib/decompress_unxz.c"
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#endif
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/* globals for tracking the state of the decompression */
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static unsigned long decompressed_bytes;
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static unsigned long limit;
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static unsigned long skip;
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static char *output_buffer;
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/*
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* flush() is called by __decompress() when the decompressor's scratch buffer is
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* full.
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*/
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static long flush(void *v, unsigned long buffer_size)
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{
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unsigned long end = decompressed_bytes + buffer_size;
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unsigned long size = buffer_size;
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unsigned long offset = 0;
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char *in = v;
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char *out;
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/*
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* if we hit our decompression limit, we need to fake an error to abort
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* the in-progress decompression.
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*/
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if (decompressed_bytes >= limit)
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return -1;
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/* skip this entire block */
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if (end <= skip) {
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decompressed_bytes += buffer_size;
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return buffer_size;
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}
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/* skip some data at the start, but keep the rest of the block */
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if (decompressed_bytes < skip && end > skip) {
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offset = skip - decompressed_bytes;
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in += offset;
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size -= offset;
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decompressed_bytes += offset;
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}
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out = &output_buffer[decompressed_bytes - skip];
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size = min(decompressed_bytes + size, limit) - decompressed_bytes;
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memcpy(out, in, size);
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decompressed_bytes += size;
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return buffer_size;
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}
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static void print_err(char *s)
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{
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/* suppress the "error" when we terminate the decompressor */
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if (decompressed_bytes >= limit)
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return;
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printf("Decompression error: '%s'\n\r", s);
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}
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/**
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* partial_decompress - decompresses part or all of a compressed buffer
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* @inbuf: input buffer
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* @input_size: length of the input buffer
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* @outbuf: output buffer
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* @output_size: length of the output buffer
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* @_skip: number of output bytes to ignore
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*
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* This function takes compressed data from inbuf, decompresses and write it to
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* outbuf. Once output_size bytes are written to the output buffer, or the
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* stream is exhausted the function will return the number of bytes that were
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* decompressed. Otherwise it will return whatever error code the decompressor
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* reported (NB: This is specific to each decompressor type).
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*
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* The skip functionality is mainly there so the program and discover
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* the size of the compressed image so that it can ask firmware (if present)
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* for an appropriately sized buffer.
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*/
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long partial_decompress(void *inbuf, unsigned long input_size,
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void *outbuf, unsigned long output_size, unsigned long _skip)
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{
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int ret;
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/*
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* The skipped bytes needs to be included in the size of data we want
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* to decompress.
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*/
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output_size += _skip;
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decompressed_bytes = 0;
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output_buffer = outbuf;
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limit = output_size;
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skip = _skip;
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ret = __decompress(inbuf, input_size, NULL, flush, outbuf,
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output_size, NULL, print_err);
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/*
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* If decompression was aborted due to an actual error rather than
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* a fake error that we used to abort, then we should report it.
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*/
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if (decompressed_bytes < limit)
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return ret;
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return decompressed_bytes - skip;
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}
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