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d7476f24c9
With gendwarfksyms, we need each TU where the EXPORT_SYMBOL() macro is used to also contain DWARF type information for the symbols it exports. However, as a TU can also export external symbols and compilers may choose not to emit debugging information for symbols not defined in the current TU, the missing types will result in missing symbol versions. Stand-alone assembly code also doesn't contain type information for exported symbols, so we need to compile a temporary object file with asm-prototypes.h instead, and similarly need to ensure the DWARF in the temporary object file contains the necessary types. To always emit type information for external exports, add explicit __gendwarfksyms_ptr_<symbol> references to them in EXPORT_SYMBOL(). gendwarfksyms will use the type information for __gendwarfksyms_ptr_* if needed. Discard the pointers from the final binary to avoid further bloat. Signed-off-by: Sami Tolvanen <samitolvanen@google.com> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
89 lines
2.4 KiB
C
89 lines
2.4 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
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#ifndef _LINUX_EXPORT_H
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#define _LINUX_EXPORT_H
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#include <linux/compiler.h>
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#include <linux/linkage.h>
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#include <linux/stringify.h>
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/*
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* This comment block is used by fixdep. Please do not remove.
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*
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* When CONFIG_MODVERSIONS is changed from n to y, all source files having
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* EXPORT_SYMBOL variants must be re-compiled because genksyms is run as a
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* side effect of the *.o build rule.
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*/
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#ifdef CONFIG_64BIT
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#define __EXPORT_SYMBOL_REF(sym) \
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.balign 8 ASM_NL \
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.quad sym
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#else
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#define __EXPORT_SYMBOL_REF(sym) \
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.balign 4 ASM_NL \
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.long sym
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#endif
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#define ___EXPORT_SYMBOL(sym, license, ns) \
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.section ".export_symbol","a" ASM_NL \
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__export_symbol_##sym: ASM_NL \
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.asciz license ASM_NL \
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.asciz ns ASM_NL \
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__EXPORT_SYMBOL_REF(sym) ASM_NL \
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.previous
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#if 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, license, ns)
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#elif defined(__GENKSYMS__)
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#define __EXPORT_SYMBOL(sym, license, ns) __GENKSYMS_EXPORT_SYMBOL(sym)
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#elif defined(__ASSEMBLY__)
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#define __EXPORT_SYMBOL(sym, license, ns) \
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___EXPORT_SYMBOL(sym, license, ns)
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#else
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#ifdef CONFIG_GENDWARFKSYMS
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/*
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* With CONFIG_GENDWARFKSYMS, ensure the compiler emits debugging
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* information for all exported symbols, including those defined in
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* different TUs, by adding a __gendwarfksyms_ptr_<symbol> pointer
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* that's discarded during the final link.
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*/
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#define __GENDWARFKSYMS_EXPORT(sym) \
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static typeof(sym) *__gendwarfksyms_ptr_##sym __used \
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__section(".discard.gendwarfksyms") = &sym;
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#else
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#define __GENDWARFKSYMS_EXPORT(sym)
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#endif
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#define __EXPORT_SYMBOL(sym, license, ns) \
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extern typeof(sym) sym; \
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__ADDRESSABLE(sym) \
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__GENDWARFKSYMS_EXPORT(sym) \
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asm(__stringify(___EXPORT_SYMBOL(sym, license, ns)))
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#endif
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#ifdef DEFAULT_SYMBOL_NAMESPACE
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#define _EXPORT_SYMBOL(sym, license) __EXPORT_SYMBOL(sym, license, DEFAULT_SYMBOL_NAMESPACE)
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#else
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#define _EXPORT_SYMBOL(sym, license) __EXPORT_SYMBOL(sym, license, "")
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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_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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#endif /* _LINUX_EXPORT_H */
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