// SPDX-License-Identifier: GPL-2.0-only
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/*
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* XIP kernel .data segment decompressor
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*
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* Created by: Nicolas Pitre, August 2017
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* Copyright: (C) 2017 Linaro Limited
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*/
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#include <linux/init.h>
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#include <linux/zutil.h>
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/* for struct inflate_state */
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#include "../../../lib/zlib_inflate/inftrees.h"
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#include "../../../lib/zlib_inflate/inflate.h"
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#include "../../../lib/zlib_inflate/infutil.h"
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extern char __data_loc[];
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extern char _edata_loc[];
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extern char _sdata[];
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/*
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* This code is called very early during the boot process to decompress
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* the .data segment stored compressed in ROM. Therefore none of the global
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* variables are valid yet, hence no kernel services such as memory
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* allocation is available. Everything must be allocated on the stack and
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* we must avoid any global data access. We use a temporary stack located
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* in the .bss area. The linker script makes sure the .bss is big enough
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* to hold our stack frame plus some room for called functions.
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*
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* We mimic the code in lib/decompress_inflate.c to use the smallest work
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* area possible. And because everything is statically allocated on the
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* stack then there is no need to clean up before returning.
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*/
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int __init __inflate_kernel_data(void)
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{
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struct z_stream_s stream, *strm = &stream;
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struct inflate_state state;
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char *in = __data_loc;
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int rc;
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/* Check and skip gzip header (assume no filename) */
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if (in[0] != 0x1f || in[1] != 0x8b || in[2] != 0x08 || in[3] & ~3)
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return -1;
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in += 10;
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strm->workspace = &state;
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strm->next_in = in;
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strm->avail_in = _edata_loc - __data_loc; /* upper bound */
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strm->next_out = _sdata;
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strm->avail_out = _edata_loc - __data_loc;
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zlib_inflateInit2(strm, -MAX_WBITS);
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WS(strm)->inflate_state.wsize = 0;
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WS(strm)->inflate_state.window = NULL;
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rc = zlib_inflate(strm, Z_FINISH);
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if (rc == Z_OK || rc == Z_STREAM_END)
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rc = strm->avail_out; /* should be 0 */
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return rc;
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}
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