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-rw-r--r--arch/arm/kernel/head-inflate-data.c62
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diff --git a/arch/arm/kernel/head-inflate-data.c b/arch/arm/kernel/head-inflate-data.c
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+++ b/arch/arm/kernel/head-inflate-data.c
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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;
+}