// SPDX-License-Identifier: GPL-2.0-only /* * XIP kernel .data segment decompressor * * Created by: Nicolas Pitre, August 2017 * Copyright: (C) 2017 Linaro Limited */ #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; }