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