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kbuild: link symbol CRCs at final link, removing CONFIG_MODULE_REL_CRCS
include/{linux,asm-generic}/export.h defines a weak symbol, __crc_* as a placeholder. Genksyms writes the version CRCs into the linker script, which will be used for filling the __crc_* symbols. The linker script format depends on CONFIG_MODULE_REL_CRCS. If it is enabled, __crc_* holds the offset to the reference of CRC. It is time to get rid of this complexity. Now that modpost parses text files (.*.cmd) to collect all the CRCs, it can generate C code that will be linked to the vmlinux or modules. Generate a new C file, .vmlinux.export.c, which contains the CRCs of symbols exported by vmlinux. It is compiled and linked to vmlinux in scripts/link-vmlinux.sh. Put the CRCs of symbols exported by modules into the existing *.mod.c files. No additional build step is needed for modules. As before, *.mod.c are compiled and linked to *.ko in scripts/Makefile.modfinal. No linker magic is used here. The new C implementation works in the same way, whether CONFIG_RELOCATABLE is enabled or not. CONFIG_MODULE_REL_CRCS is no longer needed. Previously, Kbuild invoked additional $(LD) to update the CRCs in objects, but this step is unneeded too. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Tested-by: Nathan Chancellor <nathan@kernel.org> Tested-by: Nicolas Schier <nicolas@fjasle.eu> Reviewed-by: Nicolas Schier <nicolas@fjasle.eu> Tested-by: Sedat Dilek <sedat.dilek@gmail.com> # LLVM-14 (x86-64)
This commit is contained in:
parent
f292d875d0
commit
7b4537199a
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@ -1,5 +1,6 @@
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# SPDX-License-Identifier: GPL-2.0
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generated-y += syscall_table.h
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generic-y += export.h
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generic-y += extable.h
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generic-y += kvm_para.h
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generic-y += mcs_spinlock.h
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@ -1,2 +0,0 @@
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#define KCRC_ALIGN 2
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#include <asm-generic/export.h>
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@ -566,7 +566,6 @@ config RELOCATABLE
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bool "Build a relocatable kernel"
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depends on PPC64 || (FLATMEM && (44x || FSL_BOOKE))
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select NONSTATIC_KERNEL
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select MODULE_REL_CRCS if MODVERSIONS
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help
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This builds a kernel image that is capable of running at the
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location the kernel is loaded at. For ppc32, there is no any
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@ -567,7 +567,6 @@ endchoice
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config RELOCATABLE
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bool "Build a relocatable kernel"
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select MODULE_REL_CRCS if MODVERSIONS
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default y
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help
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This builds a kernel image that retains relocation information
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@ -106,7 +106,6 @@ config LD_SCRIPT_DYN
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bool
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default y
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depends on !LD_SCRIPT_STATIC
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select MODULE_REL_CRCS if MODVERSIONS
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config LD_SCRIPT_DYN_RPATH
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bool "set rpath in the binary" if EXPERT
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@ -2,6 +2,14 @@
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#ifndef __ASM_GENERIC_EXPORT_H
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#define __ASM_GENERIC_EXPORT_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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#ifndef KSYM_FUNC
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#define KSYM_FUNC(x) x
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#endif
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@ -12,9 +20,6 @@
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#else
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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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.macro __put, val, name
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#ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
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@ -43,17 +48,6 @@ __ksymtab_\name:
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__kstrtab_\name:
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.asciz "\name"
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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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#if defined(CONFIG_MODULE_REL_CRCS)
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.long __crc_\name - .
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#else
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.long __crc_\name
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#endif
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.weak __crc_\name
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.previous
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#endif
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#endif
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.endm
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17
include/linux/export-internal.h
Normal file
17
include/linux/export-internal.h
Normal file
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/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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* Please do not include this explicitly.
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* This is used by C files generated by modpost.
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*/
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#ifndef __LINUX_EXPORT_INTERNAL_H__
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#define __LINUX_EXPORT_INTERNAL_H__
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#include <linux/compiler.h>
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#include <linux/types.h>
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/* __used is needed to keep __crc_* for LTO */
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#define SYMBOL_CRC(sym, crc, sec) \
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u32 __section("___kcrctab" sec "+" #sym) __used __crc_##sym = crc
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#endif /* __LINUX_EXPORT_INTERNAL_H__ */
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@ -11,6 +11,14 @@
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* hackers place grumpy comments in header files.
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*/
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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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#ifndef __ASSEMBLY__
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#ifdef MODULE
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extern struct module __this_module;
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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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/*
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* For every exported symbol, do the following:
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*
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* - If applicable, place a CRC entry in the __kcrctab section.
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* - Put the name of the symbol and namespace (empty string "" for none) in
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* __ksymtab_strings.
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* - Place a struct kernel_symbol entry in the __ksymtab section.
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extern typeof(sym) sym; \
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extern const char __kstrtab_##sym[]; \
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extern const char __kstrtabns_##sym[]; \
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__CRC_SYMBOL(sym, sec); \
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asm(" .section \"__ksymtab_strings\",\"aMS\",%progbits,1 \n" \
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"__kstrtab_" #sym ": \n" \
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" .asciz \"" #sym "\" \n" \
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@ -2136,10 +2136,6 @@ config ASM_MODVERSIONS
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assembly. This can be enabled only when the target architecture
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supports it.
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config MODULE_REL_CRCS
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bool
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depends on MODVERSIONS
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config MODULE_SRCVERSION_ALL
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bool "Source checksum for all modules"
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help
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@ -1231,11 +1231,6 @@ static int try_to_force_load(struct module *mod, const char *reason)
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#ifdef CONFIG_MODVERSIONS
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static u32 resolve_rel_crc(const s32 *crc)
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{
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return *(u32 *)((void *)crc + *crc);
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}
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static int check_version(const struct load_info *info,
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const char *symname,
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struct module *mod,
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if (strcmp(versions[i].name, symname) != 0)
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continue;
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if (IS_ENABLED(CONFIG_MODULE_REL_CRCS))
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crcval = resolve_rel_crc(crc);
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else
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crcval = *crc;
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if (versions[i].crc == crcval)
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return 1;
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@ -128,7 +128,6 @@ $(obj)/%.i: $(src)/%.c FORCE
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genksyms = scripts/genksyms/genksyms \
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$(if $(1), -T $(2)) \
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$(if $(CONFIG_MODULE_REL_CRCS), -R) \
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$(if $(KBUILD_PRESERVE), -p) \
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-r $(or $(wildcard $(2:.symtypes=.symref)), /dev/null)
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# o if <file>.o doesn't contain a __ksymtab version, i.e. does
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# not export symbols, it's done.
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# o otherwise, we calculate symbol versions using the good old
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# genksyms on the preprocessed source and postprocess them in a way
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# that they are usable as a linker script
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# o generate .tmp_<file>.o from <file>.o using the linker to
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# replace the unresolved symbols __crc_exported_symbol with
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# the actual value of the checksum generated by genksyms
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# o remove .tmp_<file>.o to <file>.o
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# genksyms on the preprocessed source and dump them into the .cmd file.
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# o modpost will extract versions from that file and create *.c files that will
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# be compiled and linked to the kernel and/or modules.
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# Generate .o.symversions files for each .o with exported symbols, and link these
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# to the kernel and/or modules at the end.
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genksyms_format_rel_crc := [^_]*__crc_\([^ ]*\) = \.; LONG(\([^)]*\)).*
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genksyms_format_normal := __crc_\(.*\) = \(.*\);
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genksyms_format := $(if $(CONFIG_MODULE_REL_CRCS),$(genksyms_format_rel_crc),$(genksyms_format_normal))
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genksyms_format := __crc_\(.*\) = \(.*\);
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gen_symversions = \
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if $(NM) $@ 2>/dev/null | grep -q __ksymtab; then \
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cmd_gen_symversions_c = $(call gen_symversions,c)
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cmd_modversions = \
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if [ -r $@.symversions ]; then \
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$(LD) $(KBUILD_LDFLAGS) -r -o $(@D)/.tmp_$(@F) $@ \
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-T $@.symversions; \
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mv -f $(@D)/.tmp_$(@F) $@; \
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fi
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endif
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ifdef CONFIG_FTRACE_MCOUNT_USE_RECORDMCOUNT
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$(call cmd,checkdoc)
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$(call cmd,gen_objtooldep)
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$(call cmd,gen_symversions_c)
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$(if $(CONFIG_LTO_CLANG),,$(call cmd,modversions))
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$(call cmd,record_mcount)
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endef
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$(call cmd,gen_ksymdeps)
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$(call cmd,gen_objtooldep)
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$(call cmd,gen_symversions_S)
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$(call cmd,modversions)
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endef
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# Built-in and composite module parts
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quiet_cmd_cc_prelink_modules = LD [M] $@
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cmd_cc_prelink_modules = \
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$(LD) $(ld_flags) -r -o $@ \
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$(shell [ -s $(@:.prelink.o=.o.symversions) ] && \
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echo -T $(@:.prelink.o=.o.symversions)) \
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--whole-archive $(filter-out FORCE,$^) \
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$(cmd_objtool)
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32
scripts/Makefile.vmlinux
Normal file
32
scripts/Makefile.vmlinux
Normal file
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# SPDX-License-Identifier: GPL-2.0-only
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include include/config/auto.conf
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include $(srctree)/scripts/Kbuild.include
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# for c_flags
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include $(srctree)/scripts/Makefile.lib
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quiet_cmd_cc_o_c = CC $@
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cmd_cc_o_c = $(CC) $(c_flags) -c -o $@ $<
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%.o: %.c FORCE
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$(call if_changed_dep,cc_o_c)
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targets := $(MAKECMDGOALS)
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# Add FORCE to the prequisites of a target to force it to be always rebuilt.
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# ---------------------------------------------------------------------------
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PHONY += FORCE
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FORCE:
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# Read all saved command lines and dependencies for the $(targets) we
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# may be building above, using $(if_changed{,_dep}). As an
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# optimization, we don't need to read them if the target does not
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# exist, we will rebuild anyway in that case.
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existing-targets := $(wildcard $(sort $(targets)))
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-include $(foreach f,$(existing-targets),$(dir $(f)).$(notdir $(f)).cmd)
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.PHONY: $(PHONY)
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@ -33,7 +33,7 @@ char *cur_filename;
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int in_source_file;
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static int flag_debug, flag_dump_defs, flag_reference, flag_dump_types,
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flag_preserve, flag_warnings, flag_rel_crcs;
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flag_preserve, flag_warnings;
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static int errors;
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static int nsyms;
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if (flag_dump_defs)
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fputs(">\n", debugfile);
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/* Used as a linker script. */
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printf(!flag_rel_crcs ? "__crc_%s = 0x%08lx;\n" :
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"SECTIONS { .rodata : ALIGN(4) { "
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"__crc_%s = .; LONG(0x%08lx); } }\n",
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name, crc);
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printf("__crc_%s = 0x%08lx;\n", name, crc);
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}
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}
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@ -733,7 +729,6 @@ static void genksyms_usage(void)
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" -q, --quiet Disable warnings (default)\n"
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" -h, --help Print this message\n"
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" -V, --version Print the release version\n"
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" -R, --relative-crc Emit section relative symbol CRCs\n"
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#else /* __GNU_LIBRARY__ */
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" -s Select symbol prefix\n"
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" -d Increment the debug level (repeatable)\n"
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@ -745,7 +740,6 @@ static void genksyms_usage(void)
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" -q Disable warnings (default)\n"
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" -h Print this message\n"
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" -V Print the release version\n"
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" -R Emit section relative symbol CRCs\n"
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#endif /* __GNU_LIBRARY__ */
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, stderr);
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}
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@ -766,14 +760,13 @@ int main(int argc, char **argv)
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{"preserve", 0, 0, 'p'},
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{"version", 0, 0, 'V'},
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{"help", 0, 0, 'h'},
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{"relative-crc", 0, 0, 'R'},
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{0, 0, 0, 0}
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};
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while ((o = getopt_long(argc, argv, "s:dwqVDr:T:phR",
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while ((o = getopt_long(argc, argv, "s:dwqVDr:T:ph",
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&long_opts[0], NULL)) != EOF)
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#else /* __GNU_LIBRARY__ */
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while ((o = getopt(argc, argv, "s:dwqVDr:T:phR")) != EOF)
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while ((o = getopt(argc, argv, "s:dwqVDr:T:ph")) != EOF)
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#endif /* __GNU_LIBRARY__ */
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switch (o) {
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case 'd':
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@ -813,9 +806,6 @@ int main(int argc, char **argv)
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case 'h':
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genksyms_usage();
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return 0;
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case 'R':
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flag_rel_crcs = 1;
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break;
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default:
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genksyms_usage();
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return 1;
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@ -90,7 +90,6 @@ modpost_link()
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if is_enabled CONFIG_MODVERSIONS; then
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gen_symversions
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lds="${lds} -T .tmp_symversions.lds"
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fi
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# This might take a while, so indicate that we're doing
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@ -183,6 +182,10 @@ vmlinux_link()
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libs="${KBUILD_VMLINUX_LIBS}"
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fi
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if is_enabled CONFIG_MODULES; then
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objs="${objs} .vmlinux.export.o"
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fi
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if [ "${SRCARCH}" = "um" ]; then
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wl=-Wl,
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ld="${CC}"
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@ -312,6 +315,7 @@ cleanup()
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rm -f vmlinux.o
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rm -f .vmlinux.d
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rm -f .vmlinux.objs
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rm -f .vmlinux.export.c
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}
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# Use "make V=1" to debug this script
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@ -363,6 +367,10 @@ info GEN modules.builtin
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tr '\0' '\n' < modules.builtin.modinfo | sed -n 's/^[[:alnum:]:_]*\.file=//p' |
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tr ' ' '\n' | uniq | sed -e 's:^:kernel/:' -e 's/$/.ko/' > modules.builtin
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if is_enabled CONFIG_MODULES; then
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${MAKE} -f "${srctree}/scripts/Makefile.vmlinux" .vmlinux.export.o
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fi
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btf_vmlinux_bin_o=""
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if is_enabled CONFIG_DEBUG_INFO_BTF; then
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btf_vmlinux_bin_o=.btf.vmlinux.bin.o
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@ -2234,6 +2234,7 @@ static void add_header(struct buffer *b, struct module *mod)
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buf_printf(b, "#define INCLUDE_VERMAGIC\n");
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buf_printf(b, "#include <linux/build-salt.h>\n");
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buf_printf(b, "#include <linux/elfnote-lto.h>\n");
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buf_printf(b, "#include <linux/export-internal.h>\n");
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buf_printf(b, "#include <linux/vermagic.h>\n");
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buf_printf(b, "#include <linux/compiler.h>\n");
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buf_printf(b, "\n");
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||||
|
@ -2268,20 +2269,26 @@ static void add_header(struct buffer *b, struct module *mod)
|
|||
buf_printf(b, "\nMODULE_INFO(staging, \"Y\");\n");
|
||||
}
|
||||
|
||||
static void check_symversions(struct module *mod)
|
||||
static void add_exported_symbols(struct buffer *buf, struct module *mod)
|
||||
{
|
||||
struct symbol *sym;
|
||||
|
||||
if (!modversions)
|
||||
return;
|
||||
|
||||
/* record CRCs for exported symbols */
|
||||
buf_printf(buf, "\n");
|
||||
list_for_each_entry(sym, &mod->exported_symbols, list) {
|
||||
if (!sym->crc_valid) {
|
||||
warn("EXPORT symbol \"%s\" [%s%s] version generation failed, symbol will not be versioned.\n"
|
||||
"Is \"%s\" prototyped in <asm/asm-prototypes.h>?\n",
|
||||
sym->name, mod->name, mod->is_vmlinux ? "" : ".ko",
|
||||
sym->name);
|
||||
continue;
|
||||
}
|
||||
|
||||
buf_printf(buf, "SYMBOL_CRC(%s, 0x%08x, \"%s\");\n",
|
||||
sym->name, sym->crc, sym->is_gpl_only ? "_gpl" : "");
|
||||
}
|
||||
}
|
||||
|
||||
|
@ -2418,6 +2425,18 @@ static void write_if_changed(struct buffer *b, const char *fname)
|
|||
write_buf(b, fname);
|
||||
}
|
||||
|
||||
static void write_vmlinux_export_c_file(struct module *mod)
|
||||
{
|
||||
struct buffer buf = { };
|
||||
|
||||
buf_printf(&buf,
|
||||
"#include <linux/export-internal.h>\n");
|
||||
|
||||
add_exported_symbols(&buf, mod);
|
||||
write_if_changed(&buf, ".vmlinux.export.c");
|
||||
free(buf.p);
|
||||
}
|
||||
|
||||
/* do sanity checks, and generate *.mod.c file */
|
||||
static void write_mod_c_file(struct module *mod)
|
||||
{
|
||||
|
@ -2429,6 +2448,7 @@ static void write_mod_c_file(struct module *mod)
|
|||
check_exports(mod);
|
||||
|
||||
add_header(&buf, mod);
|
||||
add_exported_symbols(&buf, mod);
|
||||
add_versions(&buf, mod);
|
||||
add_depends(&buf, mod);
|
||||
add_moddevtable(&buf, mod);
|
||||
|
@ -2626,9 +2646,9 @@ int main(int argc, char **argv)
|
|||
if (mod->from_dump)
|
||||
continue;
|
||||
|
||||
check_symversions(mod);
|
||||
|
||||
if (!mod->is_vmlinux)
|
||||
if (mod->is_vmlinux)
|
||||
write_vmlinux_export_c_file(mod);
|
||||
else
|
||||
write_mod_c_file(mod);
|
||||
}
|
||||
|
||||
|
|
Loading…
Reference in a new issue