zstd: Move zstd-common module exports to zstd_common_module.c

The zstd codebase is imported from the upstream zstd repo, and is over-written on
every update. Upstream keeps the kernel specific code separate from the main
library. So the module definition is moved into the zstd_common_module.c file.
This matches the pattern followed by the zstd-compress and zstd-decompress files.

I've done build and boot testing on x86-64, i386, and aarch64. I've
verified that zstd built both as modules and built-in build and boot.

Signed-off-by: Nick Terrell <terrelln@fb.com>

lib/zstd/Makefile

@@ -35,6 +35,7 @@ zstd_decompress-y := \
 		decompress/zstd_decompress_block.o \
 
 zstd_common-y := \
+		zstd_common_module.o \
 		common/debug.o \
 		common/entropy_common.o \
 		common/error_private.o \

lib/zstd/common/entropy_common.c

@@ -15,7 +15,6 @@
 /* *************************************
 *  Dependencies
 ***************************************/
-#include <linux/module.h>
 #include "mem.h"
 #include "error_private.h"       /* ERR_*, ERROR */
 #define FSE_STATIC_LINKING_ONLY  /* FSE_MIN_TABLELOG */
@@ -240,7 +239,6 @@ size_t FSE_readNCount(
 {
     return FSE_readNCount_bmi2(normalizedCounter, maxSVPtr, tableLogPtr, headerBuffer, hbSize, /* bmi2 */ 0);
 }
-EXPORT_SYMBOL_GPL(FSE_readNCount);
 
 /*! HUF_readStats() :
     Read compact Huffman tree, saved by HUF_writeCTable().
@@ -256,7 +254,6 @@ size_t HUF_readStats(BYTE* huffWeight, size_t hwSize, U32* rankStats,
     U32 wksp[HUF_READ_STATS_WORKSPACE_SIZE_U32];
     return HUF_readStats_wksp(huffWeight, hwSize, rankStats, nbSymbolsPtr, tableLogPtr, src, srcSize, wksp, sizeof(wksp), /* bmi2 */ 0);
 }
-EXPORT_SYMBOL_GPL(HUF_readStats);
 
 FORCE_INLINE_TEMPLATE size_t
 HUF_readStats_body(BYTE* huffWeight, size_t hwSize, U32* rankStats,
@@ -357,4 +354,3 @@ size_t HUF_readStats_wksp(BYTE* huffWeight, size_t hwSize, U32* rankStats,
     (void)bmi2;
     return HUF_readStats_body_default(huffWeight, hwSize, rankStats, nbSymbolsPtr, tableLogPtr, src, srcSize, workSpace, wkspSize);
 }
-EXPORT_SYMBOL_GPL(HUF_readStats_wksp);

lib/zstd/common/zstd_common.c

@@ -13,7 +13,6 @@
 /*-*************************************
 *  Dependencies
 ***************************************/
-#include <linux/module.h>
 #define ZSTD_DEPS_NEED_MALLOC
 #include "zstd_deps.h"   /* ZSTD_malloc, ZSTD_calloc, ZSTD_free, ZSTD_memset */
 #include "error_private.h"
@@ -36,17 +35,14 @@ const char* ZSTD_versionString(void) { return ZSTD_VERSION_STRING; }
  *  tells if a return value is an error code
  *  symbol is required for external callers */
 unsigned ZSTD_isError(size_t code) { return ERR_isError(code); }
-EXPORT_SYMBOL_GPL(ZSTD_isError);
 
 /*! ZSTD_getErrorName() :
  *  provides error code string from function result (useful for debugging) */
 const char* ZSTD_getErrorName(size_t code) { return ERR_getErrorName(code); }
-EXPORT_SYMBOL_GPL(ZSTD_getErrorName);
 
 /*! ZSTD_getError() :
  *  convert a `size_t` function result into a proper ZSTD_errorCode enum */
 ZSTD_ErrorCode ZSTD_getErrorCode(size_t code) { return ERR_getErrorCode(code); }
-EXPORT_SYMBOL_GPL(ZSTD_getErrorCode);
 
 /*! ZSTD_getErrorString() :
  *  provides error code string from enum */
@@ -63,7 +59,6 @@ void* ZSTD_customMalloc(size_t size, ZSTD_customMem customMem)
         return customMem.customAlloc(customMem.opaque, size);
     return ZSTD_malloc(size);
 }
-EXPORT_SYMBOL_GPL(ZSTD_customMalloc);
 
 void* ZSTD_customCalloc(size_t size, ZSTD_customMem customMem)
 {
@@ -76,7 +71,6 @@ void* ZSTD_customCalloc(size_t size, ZSTD_customMem customMem)
     }
     return ZSTD_calloc(1, size);
 }
-EXPORT_SYMBOL_GPL(ZSTD_customCalloc);
 
 void ZSTD_customFree(void* ptr, ZSTD_customMem customMem)
 {
@@ -87,7 +81,3 @@ void ZSTD_customFree(void* ptr, ZSTD_customMem customMem)
             ZSTD_free(ptr);
     }
 }
-EXPORT_SYMBOL_GPL(ZSTD_customFree);
-
-MODULE_LICENSE("Dual BSD/GPL");
-MODULE_DESCRIPTION("Zstd Common");

lib/zstd/zstd_common_module.c

@@ -0,0 +1,32 @@
+// SPDX-License-Identifier: GPL-2.0+ OR BSD-3-Clause
+/*
+ * Copyright (c) Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under both the BSD-style license (found in the
+ * LICENSE file in the root directory of this source tree) and the GPLv2 (found
+ * in the COPYING file in the root directory of this source tree).
+ * You may select, at your option, one of the above-listed licenses.
+ */
+
+#include <linux/module.h>
+
+#include "common/huf.h"
+#include "common/fse.h"
+#include "common/zstd_internal.h"
+
+// Export symbols shared by compress and decompress into a common module
+
+#undef ZSTD_isError   /* defined within zstd_internal.h */
+EXPORT_SYMBOL_GPL(FSE_readNCount);
+EXPORT_SYMBOL_GPL(HUF_readStats);
+EXPORT_SYMBOL_GPL(HUF_readStats_wksp);
+EXPORT_SYMBOL_GPL(ZSTD_isError);
+EXPORT_SYMBOL_GPL(ZSTD_getErrorName);
+EXPORT_SYMBOL_GPL(ZSTD_getErrorCode);
+EXPORT_SYMBOL_GPL(ZSTD_customMalloc);
+EXPORT_SYMBOL_GPL(ZSTD_customCalloc);
+EXPORT_SYMBOL_GPL(ZSTD_customFree);
+
+MODULE_LICENSE("Dual BSD/GPL");
+MODULE_DESCRIPTION("Zstd Common");