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c3a6cf19e6
include/linux/export.h has lots of code duplication between EXPORT_SYMBOL and EXPORT_SYMBOL_NS. To improve the maintainability and readability, unify the implementation. When the symbol has no namespace, pass the empty string "" to the 'ns' parameter. The drawback of this change is, it grows the code size. When the symbol has no namespace, sym->namespace was previously NULL, but it is now an empty string "". So, it increases 1 byte for every no namespace EXPORT_SYMBOL. A typical kernel configuration has 10K exported symbols, so it increases 10KB in rough estimation. I did not come up with a good idea to refactor it without increasing the code size. I am not sure how big a deal it is, but at least include/linux/export.h looks nicer. Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> [maennich: rebase on top of 3 fixes for the namespace feature] Signed-off-by: Matthias Maennich <maennich@google.com> Signed-off-by: Jessica Yu <jeyu@kernel.org>
160 lines
4.9 KiB
C
160 lines
4.9 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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#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(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 __kstrtabns_" #sym "- . \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(sym, sec) \
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static const struct kernel_symbol __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, __kstrtabns_##sym }
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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, ns) __GENKSYMS_EXPORT_SYMBOL(sym)
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#else
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/* For every exported symbol, place a struct in the __ksymtab section */
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#define ___EXPORT_SYMBOL(sym, sec, ns) \
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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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static const char __kstrtabns_##sym[] \
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__attribute__((section("__ksymtab_strings"), used, aligned(1))) \
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= ns; \
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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(sym, sec, ns)
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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, ns) \
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__ksym_marker(sym); \
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__cond_export_sym(sym, sec, ns, __is_defined(__KSYM_##sym))
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#define __cond_export_sym(sym, sec, ns, conf) \
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___cond_export_sym(sym, sec, ns, conf)
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#define ___cond_export_sym(sym, sec, ns, enabled) \
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__cond_export_sym_##enabled(sym, sec, ns)
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#define __cond_export_sym_1(sym, sec, ns) ___EXPORT_SYMBOL(sym, sec, ns)
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#define __cond_export_sym_0(sym, sec, ns) /* nothing */
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#else
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#define __EXPORT_SYMBOL(sym, sec, ns) ___EXPORT_SYMBOL(sym, sec, ns)
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#endif /* CONFIG_MODULES */
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#ifdef DEFAULT_SYMBOL_NAMESPACE
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#include <linux/stringify.h>
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#define _EXPORT_SYMBOL(sym, sec) __EXPORT_SYMBOL(sym, sec, __stringify(DEFAULT_SYMBOL_NAMESPACE))
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#else
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#define _EXPORT_SYMBOL(sym, sec) __EXPORT_SYMBOL(sym, sec, "")
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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(sym, "", #ns)
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#define EXPORT_SYMBOL_NS_GPL(sym, ns) __EXPORT_SYMBOL(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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