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kbuild: Check for functions with ambiguous -ffunction-sections section names 

Commit 9c7dc1dd89 ("objtool: Warn on functions with ambiguous
-ffunction-sections section names") only works for drivers which are
compiled on architectures supported by objtool.

Make a script to perform the same check for all architectures.

Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://patch.msgid.link/a6a49644a34964f7e02f3a8ce43af03e72817180.1763669451.git.jpoimboe@kernel.org
This commit is contained in:
Josh Poimboeuf 2025-11-20 12:14:20 -08:00 committed by Peter Zijlstra
parent 3186333713
commit 93863f3f85
3 changed files with 30 additions and 1 deletions
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2
include/asm-generic/vmlinux.lds.h
View File

@ -110,7 +110,7 @@
* .text.startup could be __attribute__((constructor)) code in a *non* * .text.startup could be __attribute__((constructor)) code in a *non*
* ffunction-sections object, which should be placed in .init.text; or it could * ffunction-sections object, which should be placed in .init.text; or it could
* be an actual function named startup() in an ffunction-sections object, which * be an actual function named startup() in an ffunction-sections object, which
* should be placed in .text. Objtool will detect and complain about any such * should be placed in .text. The build will detect and complain about any such
* ambiguously named functions. * ambiguously named functions.
*/ */
#define TEXT_MAIN \ #define TEXT_MAIN \

4
scripts/Makefile.vmlinux_o
View File

@ -63,11 +63,15 @@ quiet_cmd_ld_vmlinux.o = LD $@
--start-group $(KBUILD_VMLINUX_LIBS) --end-group \ --start-group $(KBUILD_VMLINUX_LIBS) --end-group \
$(cmd_objtool) $(cmd_objtool)
cmd_check_function_names = $(srctree)/scripts/check-function-names.sh $@
define rule_ld_vmlinux.o define rule_ld_vmlinux.o
$(call cmd_and_savecmd,ld_vmlinux.o) $(call cmd_and_savecmd,ld_vmlinux.o)
$(call cmd,gen_objtooldep) $(call cmd,gen_objtooldep)
$(call cmd,check_function_names)
endef endef
vmlinux.o: $(initcalls-lds) vmlinux.a $(KBUILD_VMLINUX_LIBS) FORCE vmlinux.o: $(initcalls-lds) vmlinux.a $(KBUILD_VMLINUX_LIBS) FORCE
$(call if_changed_rule,ld_vmlinux.o) $(call if_changed_rule,ld_vmlinux.o)

25
scripts/check-function-names.sh Executable file
View File

@ -0,0 +1,25 @@
#!/bin/sh
# SPDX-License-Identifier: GPL-2.0
#
# Certain function names are disallowed due to section name ambiguities
# introduced by -ffunction-sections.
#
# See the comment above TEXT_MAIN in include/asm-generic/vmlinux.lds.h.
objfile="$1"
if [ ! -f "$objfile" ]; then
echo "usage: $0 <file.o>" >&2
exit 1
fi
bad_symbols=$(nm "$objfile" | awk '$2 ~ /^[TtWw]$/ {print $3}' | grep -E '^(startup|exit|split|unlikely|hot|unknown)(\.|$)')
if [ -n "$bad_symbols" ]; then
echo "$bad_symbols" | while read -r sym; do
echo "$objfile: error: $sym() function name creates ambiguity with -ffunction-sections" >&2
done
exit 1
fi
exit 0