8ab2ae655b
With binutils-2.26 and before, a weak missing symbol was kept during the final link, and a missing CRC for an export would lead to that CRC being treated as zero implicitly. With binutils-2.27, the crc symbol gets dropped, and any module trying to use it will fail to load. This sets the weak CRC symbol to zero explicitly, making it defined in vmlinux, which in turn lets us load the modules referring to that CRC. The comment above the __CRC_SYMBOL macro suggests that this was always the intention, although it also seems that all symbols defined in C have a correct CRC these days, and only the exports that are now done in assembly need this. Signed-off-by: Arnd Bergmann <arnd@arndb.de> Tested-by: Adam Borowski <kilobyte@angband.pl> Cc: stable@kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
95 lines
2.2 KiB
C
95 lines
2.2 KiB
C
#ifndef __ASM_GENERIC_EXPORT_H
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#define __ASM_GENERIC_EXPORT_H
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#ifndef KSYM_FUNC
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#define KSYM_FUNC(x) x
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#endif
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#ifdef CONFIG_64BIT
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#define __put .quad
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#ifndef KSYM_ALIGN
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#define KSYM_ALIGN 8
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#endif
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#ifndef KCRC_ALIGN
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#define KCRC_ALIGN 8
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#endif
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#else
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#define __put .long
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#ifndef KSYM_ALIGN
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#define KSYM_ALIGN 4
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#endif
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#ifndef KCRC_ALIGN
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#define KCRC_ALIGN 4
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#endif
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#endif
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#ifdef CONFIG_HAVE_UNDERSCORE_SYMBOL_PREFIX
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#define KSYM(name) _##name
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#else
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#define KSYM(name) name
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#endif
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/*
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* note on .section use: @progbits vs %progbits nastiness doesn't matter,
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* since we immediately emit into those sections anyway.
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*/
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.macro ___EXPORT_SYMBOL name,val,sec
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#ifdef CONFIG_MODULES
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.globl KSYM(__ksymtab_\name)
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.section ___ksymtab\sec+\name,"a"
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.balign KSYM_ALIGN
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KSYM(__ksymtab_\name):
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__put \val, KSYM(__kstrtab_\name)
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.previous
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.section __ksymtab_strings,"a"
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KSYM(__kstrtab_\name):
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#ifdef CONFIG_HAVE_UNDERSCORE_SYMBOL_PREFIX
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.asciz "_\name"
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#else
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.asciz "\name"
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#endif
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.previous
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#ifdef CONFIG_MODVERSIONS
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.section ___kcrctab\sec+\name,"a"
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.balign KCRC_ALIGN
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KSYM(__kcrctab_\name):
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__put KSYM(__crc_\name)
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.weak KSYM(__crc_\name)
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.set KSYM(__crc_\name), 0
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.previous
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#endif
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#endif
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.endm
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#undef __put
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#if defined(__KSYM_DEPS__)
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#define __EXPORT_SYMBOL(sym, val, sec) === __KSYM_##sym ===
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#elif defined(CONFIG_TRIM_UNUSED_KSYMS)
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#include <linux/kconfig.h>
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#include <generated/autoksyms.h>
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#define __EXPORT_SYMBOL(sym, val, sec) \
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__cond_export_sym(sym, val, sec, __is_defined(__KSYM_##sym))
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#define __cond_export_sym(sym, val, sec, conf) \
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___cond_export_sym(sym, val, sec, conf)
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#define ___cond_export_sym(sym, val, sec, enabled) \
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__cond_export_sym_##enabled(sym, val, sec)
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#define __cond_export_sym_1(sym, val, sec) ___EXPORT_SYMBOL sym, val, sec
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#define __cond_export_sym_0(sym, val, sec) /* nothing */
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#else
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#define __EXPORT_SYMBOL(sym, val, sec) ___EXPORT_SYMBOL sym, val, sec
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#endif
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#define EXPORT_SYMBOL(name) \
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__EXPORT_SYMBOL(name, KSYM_FUNC(KSYM(name)),)
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#define EXPORT_SYMBOL_GPL(name) \
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__EXPORT_SYMBOL(name, KSYM_FUNC(KSYM(name)), _gpl)
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#define EXPORT_DATA_SYMBOL(name) \
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__EXPORT_SYMBOL(name, KSYM(name),)
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#define EXPORT_DATA_SYMBOL_GPL(name) \
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__EXPORT_SYMBOL(name, KSYM(name),_gpl)
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#endif
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