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Diffstat (limited to 'arch/arm/kernel/head-inflate-data.c')
-rw-r--r-- | arch/arm/kernel/head-inflate-data.c | 56 |
1 files changed, 56 insertions, 0 deletions
diff --git a/arch/arm/kernel/head-inflate-data.c b/arch/arm/kernel/head-inflate-data.c new file mode 100644 index 0000000000..225c0699a1 --- /dev/null +++ b/arch/arm/kernel/head-inflate-data.c @@ -0,0 +1,56 @@ +// 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> +#include "head.h" + +/* for struct inflate_state */ +#include "../../../lib/zlib_inflate/inftrees.h" +#include "../../../lib/zlib_inflate/inflate.h" +#include "../../../lib/zlib_inflate/infutil.h" + +/* + * 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; +} |