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Diffstat (limited to 'include/linux/export.h')
| -rw-r--r-- | include/linux/export.h | 157 |
1 files changed, 157 insertions, 0 deletions
diff --git a/include/linux/export.h b/include/linux/export.h new file mode 100644 index 000000000..3f31ced0d --- /dev/null +++ b/include/linux/export.h @@ -0,0 +1,157 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +#ifndef _LINUX_EXPORT_H +#define _LINUX_EXPORT_H + +#include <linux/stringify.h> + +/* + * Export symbols from the kernel to modules. Forked from module.h + * to reduce the amount of pointless cruft we feed to gcc when only + * exporting a simple symbol or two. + * + * Try not to add #includes here. It slows compilation and makes kernel + * hackers place grumpy comments in header files. + */ + +/* + * This comment block is used by fixdep. Please do not remove. + * + * When CONFIG_MODVERSIONS is changed from n to y, all source files having + * EXPORT_SYMBOL variants must be re-compiled because genksyms is run as a + * side effect of the *.o build rule. + */ + +#ifndef __ASSEMBLY__ +#ifdef MODULE +extern struct module __this_module; +#define THIS_MODULE (&__this_module) +#else +#define THIS_MODULE ((struct module *)0) +#endif + +#ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS +#include <linux/compiler.h> +/* + * Emit the ksymtab entry as a pair of relative references: this reduces + * the size by half on 64-bit architectures, and eliminates the need for + * absolute relocations that require runtime processing on relocatable + * kernels. + */ +#define __KSYMTAB_ENTRY(sym, sec) \ + __ADDRESSABLE(sym) \ + asm(" .section \"___ksymtab" sec "+" #sym "\", \"a\" \n" \ + " .balign 4 \n" \ + "__ksymtab_" #sym ": \n" \ + " .long " #sym "- . \n" \ + " .long __kstrtab_" #sym "- . \n" \ + " .long __kstrtabns_" #sym "- . \n" \ + " .previous \n") + +struct kernel_symbol { + int value_offset; + int name_offset; + int namespace_offset; +}; +#else +#define __KSYMTAB_ENTRY(sym, sec) \ + static const struct kernel_symbol __ksymtab_##sym \ + __attribute__((section("___ksymtab" sec "+" #sym), used)) \ + __aligned(sizeof(void *)) \ + = { (unsigned long)&sym, __kstrtab_##sym, __kstrtabns_##sym } + +struct kernel_symbol { + unsigned long value; + const char *name; + const char *namespace; +}; +#endif + +#ifdef __GENKSYMS__ + +#define ___EXPORT_SYMBOL(sym, sec, ns) __GENKSYMS_EXPORT_SYMBOL(sym) + +#else + +/* + * For every exported symbol, do the following: + * + * - Put the name of the symbol and namespace (empty string "" for none) in + * __ksymtab_strings. + * - Place a struct kernel_symbol entry in the __ksymtab section. + * + * note on .section use: we specify progbits since usage of the "M" (SHF_MERGE) + * section flag requires it. Use '%progbits' instead of '@progbits' since the + * former apparently works on all arches according to the binutils source. + */ +#define ___EXPORT_SYMBOL(sym, sec, ns) \ + extern typeof(sym) sym; \ + extern const char __kstrtab_##sym[]; \ + extern const char __kstrtabns_##sym[]; \ + asm(" .section \"__ksymtab_strings\",\"aMS\",%progbits,1 \n" \ + "__kstrtab_" #sym ": \n" \ + " .asciz \"" #sym "\" \n" \ + "__kstrtabns_" #sym ": \n" \ + " .asciz \"" ns "\" \n" \ + " .previous \n"); \ + __KSYMTAB_ENTRY(sym, sec) + +#endif + +#if !defined(CONFIG_MODULES) || defined(__DISABLE_EXPORTS) + +/* + * Allow symbol exports to be disabled completely so that C code may + * be reused in other execution contexts such as the UEFI stub or the + * decompressor. + */ +#define __EXPORT_SYMBOL(sym, sec, ns) + +#elif defined(CONFIG_TRIM_UNUSED_KSYMS) + +#include <generated/autoksyms.h> + +/* + * For fine grained build dependencies, we want to tell the build system + * about each possible exported symbol even if they're not actually exported. + * We use a symbol pattern __ksym_marker_<symbol> that the build system filters + * from the $(NM) output (see scripts/gen_ksymdeps.sh). These symbols are + * discarded in the final link stage. + */ +#define __ksym_marker(sym) \ + static int __ksym_marker_##sym[0] __section(".discard.ksym") __used + +#define __EXPORT_SYMBOL(sym, sec, ns) \ + __ksym_marker(sym); \ + __cond_export_sym(sym, sec, ns, __is_defined(__KSYM_##sym)) +#define __cond_export_sym(sym, sec, ns, conf) \ + ___cond_export_sym(sym, sec, ns, conf) +#define ___cond_export_sym(sym, sec, ns, enabled) \ + __cond_export_sym_##enabled(sym, sec, ns) +#define __cond_export_sym_1(sym, sec, ns) ___EXPORT_SYMBOL(sym, sec, ns) + +#ifdef __GENKSYMS__ +#define __cond_export_sym_0(sym, sec, ns) __GENKSYMS_EXPORT_SYMBOL(sym) +#else +#define __cond_export_sym_0(sym, sec, ns) /* nothing */ +#endif + +#else + +#define __EXPORT_SYMBOL(sym, sec, ns) ___EXPORT_SYMBOL(sym, sec, ns) + +#endif /* CONFIG_MODULES */ + +#ifdef DEFAULT_SYMBOL_NAMESPACE +#define _EXPORT_SYMBOL(sym, sec) __EXPORT_SYMBOL(sym, sec, __stringify(DEFAULT_SYMBOL_NAMESPACE)) +#else +#define _EXPORT_SYMBOL(sym, sec) __EXPORT_SYMBOL(sym, sec, "") +#endif + +#define EXPORT_SYMBOL(sym) _EXPORT_SYMBOL(sym, "") +#define EXPORT_SYMBOL_GPL(sym) _EXPORT_SYMBOL(sym, "_gpl") +#define EXPORT_SYMBOL_NS(sym, ns) __EXPORT_SYMBOL(sym, "", __stringify(ns)) +#define EXPORT_SYMBOL_NS_GPL(sym, ns) __EXPORT_SYMBOL(sym, "_gpl", __stringify(ns)) + +#endif /* !__ASSEMBLY__ */ + +#endif /* _LINUX_EXPORT_H */ |