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bf70b0503a
Currently, EXPORT_SYMBOL_NS(_GPL) constructs the kernel symbol as follows: __ksymtab_SYMBOL.NAMESPACE The sym_extract_namespace() in modpost allocates memory for the part SYMBOL.NAMESPACE when '.' is contained. One problem is that the pointer returned by strdup() is lost because the symbol name will be copied to malloc'ed memory by alloc_symbol(). No one will keep track of the pointer of strdup'ed memory. sym->namespace still points to the NAMESPACE part. So, you can free it with complicated code like this: free(sym->namespace - strlen(sym->name) - 1); It complicates memory free. To fix it elegantly, I swapped the order of the symbol and the namespace as follows: __ksymtab_NAMESPACE.SYMBOL then, simplified sym_extract_namespace() so that it allocates memory only for the NAMESPACE part. I prefer this order because it is intuitive and also matches to major languages. For example, NAMESPACE::NAME in C++, MODULE.NAME in Python. Reviewed-by: Matthias Maennich <maennich@google.com> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> Signed-off-by: Jessica Yu <jeyu@kernel.org>
200 lines
6.3 KiB
C
200 lines
6.3 KiB
C
#ifndef _LINUX_EXPORT_H
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#define _LINUX_EXPORT_H
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/*
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* Export symbols from the kernel to modules. Forked from module.h
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* to reduce the amount of pointless cruft we feed to gcc when only
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* exporting a simple symbol or two.
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*
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* Try not to add #includes here. It slows compilation and makes kernel
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* hackers place grumpy comments in header files.
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*/
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#ifndef __ASSEMBLY__
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#ifdef MODULE
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extern struct module __this_module;
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#define THIS_MODULE (&__this_module)
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#else
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#define THIS_MODULE ((struct module *)0)
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#endif
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#define NS_SEPARATOR "."
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#ifdef CONFIG_MODVERSIONS
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/* Mark the CRC weak since genksyms apparently decides not to
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* generate a checksums for some symbols */
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#if defined(CONFIG_MODULE_REL_CRCS)
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#define __CRC_SYMBOL(sym, sec) \
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asm(" .section \"___kcrctab" sec "+" #sym "\", \"a\" \n" \
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" .weak __crc_" #sym " \n" \
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" .long __crc_" #sym " - . \n" \
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" .previous \n")
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#else
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#define __CRC_SYMBOL(sym, sec) \
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asm(" .section \"___kcrctab" sec "+" #sym "\", \"a\" \n" \
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" .weak __crc_" #sym " \n" \
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" .long __crc_" #sym " \n" \
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" .previous \n")
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#endif
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#else
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#define __CRC_SYMBOL(sym, sec)
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#endif
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#ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
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#include <linux/compiler.h>
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/*
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* Emit the ksymtab entry as a pair of relative references: this reduces
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* the size by half on 64-bit architectures, and eliminates the need for
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* absolute relocations that require runtime processing on relocatable
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* kernels.
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*/
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#define __KSYMTAB_ENTRY_NS(sym, sec, ns) \
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__ADDRESSABLE(sym) \
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asm(" .section \"___ksymtab" sec "+" #sym "\", \"a\" \n" \
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" .balign 4 \n" \
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"__ksymtab_" #ns NS_SEPARATOR #sym ": \n" \
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" .long " #sym "- . \n" \
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" .long __kstrtab_" #sym "- . \n" \
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" .long __kstrtab_ns_" #sym "- . \n" \
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" .previous \n")
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#define __KSYMTAB_ENTRY(sym, sec) \
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__ADDRESSABLE(sym) \
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asm(" .section \"___ksymtab" sec "+" #sym "\", \"a\" \n" \
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" .balign 4 \n" \
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"__ksymtab_" #sym ": \n" \
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" .long " #sym "- . \n" \
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" .long __kstrtab_" #sym "- . \n" \
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" .long 0 \n" \
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" .previous \n")
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struct kernel_symbol {
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int value_offset;
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int name_offset;
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int namespace_offset;
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};
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#else
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#define __KSYMTAB_ENTRY_NS(sym, sec, ns) \
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static const struct kernel_symbol __ksymtab_##sym##__##ns \
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asm("__ksymtab_" #ns NS_SEPARATOR #sym) \
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__attribute__((section("___ksymtab" sec "+" #sym), used)) \
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__aligned(sizeof(void *)) \
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= { (unsigned long)&sym, __kstrtab_##sym, __kstrtab_ns_##sym }
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#define __KSYMTAB_ENTRY(sym, sec) \
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static const struct kernel_symbol __ksymtab_##sym \
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asm("__ksymtab_" #sym) \
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__attribute__((section("___ksymtab" sec "+" #sym), used)) \
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__aligned(sizeof(void *)) \
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= { (unsigned long)&sym, __kstrtab_##sym, NULL }
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struct kernel_symbol {
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unsigned long value;
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const char *name;
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const char *namespace;
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};
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#endif
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#ifdef __GENKSYMS__
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#define ___EXPORT_SYMBOL(sym,sec) __GENKSYMS_EXPORT_SYMBOL(sym)
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#define ___EXPORT_SYMBOL_NS(sym,sec,ns) __GENKSYMS_EXPORT_SYMBOL(sym)
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#else
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#define ___export_symbol_common(sym, sec) \
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extern typeof(sym) sym; \
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__CRC_SYMBOL(sym, sec); \
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static const char __kstrtab_##sym[] \
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__attribute__((section("__ksymtab_strings"), used, aligned(1))) \
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= #sym \
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/* For every exported symbol, place a struct in the __ksymtab section */
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#define ___EXPORT_SYMBOL_NS(sym, sec, ns) \
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___export_symbol_common(sym, sec); \
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static const char __kstrtab_ns_##sym[] \
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__attribute__((section("__ksymtab_strings"), used, aligned(1))) \
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= #ns; \
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__KSYMTAB_ENTRY_NS(sym, sec, ns)
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#define ___EXPORT_SYMBOL(sym, sec) \
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___export_symbol_common(sym, sec); \
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__KSYMTAB_ENTRY(sym, sec)
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#endif
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#if !defined(CONFIG_MODULES) || defined(__DISABLE_EXPORTS)
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/*
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* Allow symbol exports to be disabled completely so that C code may
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* be reused in other execution contexts such as the UEFI stub or the
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* decompressor.
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*/
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#define __EXPORT_SYMBOL_NS(sym, sec, ns)
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#define __EXPORT_SYMBOL(sym, sec)
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#elif defined(CONFIG_TRIM_UNUSED_KSYMS)
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#include <generated/autoksyms.h>
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/*
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* For fine grained build dependencies, we want to tell the build system
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* about each possible exported symbol even if they're not actually exported.
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* We use a symbol pattern __ksym_marker_<symbol> that the build system filters
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* from the $(NM) output (see scripts/gen_ksymdeps.sh). These symbols are
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* discarded in the final link stage.
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*/
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#define __ksym_marker(sym) \
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static int __ksym_marker_##sym[0] __section(".discard.ksym") __used
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#define __EXPORT_SYMBOL(sym, sec) \
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__ksym_marker(sym); \
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__cond_export_sym(sym, sec, __is_defined(__KSYM_##sym))
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#define __cond_export_sym(sym, sec, conf) \
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___cond_export_sym(sym, sec, conf)
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#define ___cond_export_sym(sym, sec, enabled) \
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__cond_export_sym_##enabled(sym, sec)
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#define __cond_export_sym_1(sym, sec) ___EXPORT_SYMBOL(sym, sec)
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#define __cond_export_sym_0(sym, sec) /* nothing */
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#define __EXPORT_SYMBOL_NS(sym, sec, ns) \
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__ksym_marker(sym); \
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__cond_export_ns_sym(sym, sec, ns, __is_defined(__KSYM_##sym))
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#define __cond_export_ns_sym(sym, sec, ns, conf) \
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___cond_export_ns_sym(sym, sec, ns, conf)
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#define ___cond_export_ns_sym(sym, sec, ns, enabled) \
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__cond_export_ns_sym_##enabled(sym, sec, ns)
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#define __cond_export_ns_sym_1(sym, sec, ns) ___EXPORT_SYMBOL_NS(sym, sec, ns)
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#define __cond_export_ns_sym_0(sym, sec, ns) /* nothing */
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#else
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#define __EXPORT_SYMBOL_NS(sym,sec,ns) ___EXPORT_SYMBOL_NS(sym,sec,ns)
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#define __EXPORT_SYMBOL(sym,sec) ___EXPORT_SYMBOL(sym,sec)
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#endif /* CONFIG_MODULES */
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#ifdef DEFAULT_SYMBOL_NAMESPACE
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#undef __EXPORT_SYMBOL
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#define __EXPORT_SYMBOL(sym, sec) \
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__EXPORT_SYMBOL_NS(sym, sec, DEFAULT_SYMBOL_NAMESPACE)
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#endif
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#define EXPORT_SYMBOL(sym) __EXPORT_SYMBOL(sym, "")
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#define EXPORT_SYMBOL_GPL(sym) __EXPORT_SYMBOL(sym, "_gpl")
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#define EXPORT_SYMBOL_GPL_FUTURE(sym) __EXPORT_SYMBOL(sym, "_gpl_future")
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#define EXPORT_SYMBOL_NS(sym, ns) __EXPORT_SYMBOL_NS(sym, "", ns)
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#define EXPORT_SYMBOL_NS_GPL(sym, ns) __EXPORT_SYMBOL_NS(sym, "_gpl", ns)
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#ifdef CONFIG_UNUSED_SYMBOLS
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#define EXPORT_UNUSED_SYMBOL(sym) __EXPORT_SYMBOL(sym, "_unused")
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#define EXPORT_UNUSED_SYMBOL_GPL(sym) __EXPORT_SYMBOL(sym, "_unused_gpl")
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#else
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#define EXPORT_UNUSED_SYMBOL(sym)
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#define EXPORT_UNUSED_SYMBOL_GPL(sym)
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#endif
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#endif /* !__ASSEMBLY__ */
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#endif /* _LINUX_EXPORT_H */
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