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export.h: allow for per-symbol configurable EXPORT_SYMBOL()

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Similar to include/generated/autoconf.h, include/generated/autoksyms.h
will contain a list of defines for each EXPORT_SYMBOL() that we want
active. The format is:

  #define __KSYM_<symbol_name> 1

This list will be auto-generated with another patch.  For now we only
include the preprocessor magic to automatically create or omit the
corresponding struct kernel_symbol declaration.

Given the content of include/generated/autoksyms.h may not be known in
advance, an empty file is created early on to let the build proceed.

Signed-off-by: Nicolas Pitre <nico@linaro.org>
Acked-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Nicolas Pitre 2016-01-22 01:32:26 -05:00
parent 9895c03d48
commit f235541699
2 changed files with 22 additions and 2 deletions
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2
Makefile
View file

@ -998,6 +998,8 @@ prepare2: prepare3 outputmakefile asm-generic
prepare1: prepare2 $(version_h) include/generated/utsrelease.h \
include/config/auto.conf
$(cmd_crmodverdir)
$(Q)test -e include/generated/autoksyms.h || \
touch include/generated/autoksyms.h
archprepare: archheaders archscripts prepare1 scripts_basic

22
include/linux/export.h
View file

@ -38,7 +38,7 @@ extern struct module __this_module;
#ifdef CONFIG_MODULES
#ifndef __GENKSYMS__
#if defined(__KERNEL__) && !defined(__GENKSYMS__)
#ifdef CONFIG_MODVERSIONS
/* Mark the CRC weak since genksyms apparently decides not to
* generate a checksums for some symbols */
@ -53,7 +53,7 @@ extern struct module __this_module;
#endif
/* For every exported symbol, place a struct in the __ksymtab section */
#define __EXPORT_SYMBOL(sym, sec) \
#define ___EXPORT_SYMBOL(sym, sec) \
extern typeof(sym) sym; \
__CRC_SYMBOL(sym, sec) \
static const char __kstrtab_##sym[] \
@ -65,6 +65,24 @@ extern struct module __this_module;
__attribute__((section("___ksymtab" sec "+" #sym), unused)) \
= { (unsigned long)&sym, __kstrtab_##sym }
#ifdef CONFIG_TRIM_UNUSED_KSYMS
#include <linux/kconfig.h>
#include <generated/autoksyms.h>
#define __EXPORT_SYMBOL(sym, sec) \
__cond_export_sym(sym, sec, config_enabled(__KSYM_##sym))
#define __cond_export_sym(sym, sec, conf) \
___cond_export_sym(sym, sec, conf)
#define ___cond_export_sym(sym, sec, enabled) \
__cond_export_sym_##enabled(sym, sec)
#define __cond_export_sym_1(sym, sec) ___EXPORT_SYMBOL(sym, sec)
#define __cond_export_sym_0(sym, sec) /* nothing */
#else
#define __EXPORT_SYMBOL ___EXPORT_SYMBOL
#endif
#define EXPORT_SYMBOL(sym) \
__EXPORT_SYMBOL(sym, "")