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authorNicolas Pitre <nicolas.pitre@linaro.org>2016-01-21 17:07:24 -0500
committerNicolas Pitre <nicolas.pitre@linaro.org>2016-03-29 13:30:54 -0400
commit9895c03d48115c7783c0ef0a591447d53254ef84 (patch)
tree6cd59c256bb47b9b2befdddde3322e010b91359c /scripts/Makefile.build
parentf55532a0c0b8bb6148f4e07853b876ef73bc69ca (diff)
kbuild: record needed exported symbols for modules
Kernel modules are partially linked object files with some undefined symbols that are expected to be matched with EXPORT_SYMBOL() entries from elsewhere. Each .tmp_versions/*.mod file currently contains two line of text separated by a newline character. The first line has the actual module file name while the second line has a list of object files constituting that module. Those files are parsed by modpost (scripts/mod/sumversion.c), scripts/Makefile.modpost, scripts/Makefile.modsign, etc. Only the modpost utility cares about the second line while the others retrieve only the first line. Therefore we can add a third line to record the list of undefined symbols aka required EXPORT_SYMBOL() entries for each module into that file without breaking anything. Like for the second line, symbols are separated by a blank and the list is terminated with a newline character. To avoid needless build overhead, the undefined symbols extraction is performed only when CONFIG_TRIM_UNUSED_KSYMS is selected. Signed-off-by: Nicolas Pitre <nico@linaro.org> Acked-by: Rusty Russell <rusty@rustcorp.com.au>
Diffstat (limited to 'scripts/Makefile.build')
-rw-r--r--scripts/Makefile.build13
1 files changed, 11 insertions, 2 deletions
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index e1bc1907090e..74556e5e4ec0 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -286,6 +286,13 @@ define rule_as_o_S
mv -f $(dot-target).tmp $(dot-target).cmd
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_obj) FORCE
$(call cmd,force_checksrc)
@@ -296,7 +303,8 @@ $(obj)/%.o: $(src)/%.c $(recordmcount_source) $(objtool_obj) FORCE
$(single-used-m): $(obj)/%.o: $(src)/%.c $(recordmcount_source) $(objtool_obj) FORCE
$(call cmd,force_checksrc)
$(call if_changed_rule,cc_o_c)
- @{ echo $(@:.o=.ko); echo $@; } > $(MODVERDIR)/$(@F:.o=.mod)
+ @{ echo $(@:.o=.ko); echo $@; \
+ $(cmd_undef_syms); } > $(MODVERDIR)/$(@F:.o=.mod)
quiet_cmd_cc_lst_c = MKLST $@
cmd_cc_lst_c = $(CC) $(c_flags) -g -c -o $*.o $< && \
@@ -426,7 +434,8 @@ $(call multi_depend, $(multi-used-y), .o, -objs -y)
$(multi-used-m): FORCE
$(call if_changed,link_multi-m)
- @{ echo $(@:.o=.ko); echo $(link_multi_deps); } > $(MODVERDIR)/$(@F:.o=.mod)
+ @{ echo $(@:.o=.ko); echo $(link_multi_deps); \
+ $(cmd_undef_syms); } > $(MODVERDIR)/$(@F:.o=.mod)
$(call multi_depend, $(multi-used-m), .o, -objs -y -m)
targets += $(multi-used-y) $(multi-used-m)