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| author | Masahiro Yamada <masahiroy@kernel.org> | 2020-12-04 02:55:51 +0900 |
|---|---|---|
| committer | Masahiro Yamada <masahiroy@kernel.org> | 2020-12-06 21:09:28 +0900 |
| commit | 7d32358be8acb119dcfe39b6cf67ec6d94bf1fe7 (patch) | |
| tree | cb0980de0fd312257278f0f02d27d265451f5336 /scripts | |
| parent | d5750cd3c5486e9c0fa11100df01de8ca0c13fa7 (diff) | |
| download | linux-7d32358be8acb119dcfe39b6cf67ec6d94bf1fe7.tar.gz | |
kbuild: avoid split lines in .mod files
"xargs echo" is not a safe way to remove line breaks because the input may exceed the command line limit and xargs may break it up into multiple invocations of echo. This should never happen because scripts/gen_autoksyms.sh expects all undefined symbols are placed in the second line of .mod files. One possible way is to replace "xargs echo" with "sed ':x;N;$!bx;s/\n/ /g'" or something, but I rewrote the code by using awk because it is more readable. This issue was reported by Sami Tolvanen; in his Clang LTO patch set, $(multi-used-m) is no longer an ELF object, but a thin archive that contains LLVM bitcode files. llvm-nm prints out symbols for each archive member separately, which results a lot of dupications, in some places, beyond the system-defined limit. This problem must be fixed irrespective of LTO, and we must ensure zero possibility of having this issue. Link: https://lkml.org/lkml/2020/12/1/1658 Reported-by: Sami Tolvanen <samitolvanen@google.com> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Sami Tolvanen <samitolvanen@google.com>
Diffstat (limited to 'scripts')
| -rw-r--r-- | scripts/Makefile.build | 12 |
1 files changed, 4 insertions, 8 deletions
diff --git a/scripts/Makefile.build b/scripts/Makefile.build index ae647379b579..4c058f12dd73 100644 --- a/scripts/Makefile.build +++ b/scripts/Makefile.build @@ -252,6 +252,9 @@ objtool_dep = $(objtool_obj) \ ifdef CONFIG_TRIM_UNUSED_KSYMS cmd_gen_ksymdeps = \ $(CONFIG_SHELL) $(srctree)/scripts/gen_ksymdeps.sh $@ >> $(dot-target).cmd + +# List module undefined symbols +undefined_syms = $(NM) $< | $(AWK) '$$1 == "U" { printf("%s%s", x++ ? " " : "", $$2) }'; endif define rule_cc_o_c @@ -271,13 +274,6 @@ define rule_as_o_S $(call cmd,modversions_S) endef -# List module undefined symbols (or empty line if not enabled) -ifdef CONFIG_TRIM_UNUSED_KSYMS -cmd_undef_syms = $(NM) $< | sed -n 's/^ *U //p' | xargs echo -else -cmd_undef_syms = echo -endif - # Built-in and composite module parts $(obj)/%.o: $(src)/%.c $(recordmcount_source) $(objtool_dep) FORCE $(call if_changed_rule,cc_o_c) @@ -285,7 +281,7 @@ $(obj)/%.o: $(src)/%.c $(recordmcount_source) $(objtool_dep) FORCE cmd_mod = { \ echo $(if $($*-objs)$($*-y)$($*-m), $(addprefix $(obj)/, $($*-objs) $($*-y) $($*-m)), $(@:.mod=.o)); \ - $(cmd_undef_syms); \ + $(undefined_syms) echo; \ } > $@ $(obj)/%.mod: $(obj)/%.o FORCE |