kbuild: Fix TRIM_UNUSED_KSYMS with LTO_CLANG

[linux-block.git] / scripts / Makefile.build

diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 02197cb8e3a7718a98003f85ca819eb8d10f9f99..ea549579bfb77e3b5f7c6f36cc318956604fc36f 100644 (file)
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -88,6 +88,10 @@ endif
 
 targets-for-modules := $(patsubst %.o, %.mod, $(filter %.o, $(obj-m)))
 
+ifdef CONFIG_LTO_CLANG
+targets-for-modules += $(patsubst %.o, %.lto.o, $(filter %.o, $(obj-m)))
+endif
+
 ifdef need-modorder
 targets-for-modules += $(obj)/modules.order
 endif
@@ -271,12 +275,33 @@ $(obj)/%.o: $(src)/%.c $(recordmcount_source) $$(objtool_dep) FORCE
        $(call if_changed_rule,cc_o_c)
        $(call cmd,force_checksrc)
 
+ifdef CONFIG_LTO_CLANG
+# Module .o files may contain LLVM bitcode, compile them into native code
+# before ELF processing
+quiet_cmd_cc_lto_link_modules = LTO [M] $@
+cmd_cc_lto_link_modules =                                              \
+       $(LD) $(ld_flags) -r -o $@                                      \
+               $(shell [ -s $(@:.lto.o=.o.symversions) ] &&            \
+                       echo -T $(@:.lto.o=.o.symversions))             \
+               --whole-archive $(filter-out FORCE,$^)
+
+ifdef CONFIG_STACK_VALIDATION
+# objtool was skipped for LLVM bitcode, run it now that we have compiled
+# modules into native code
+cmd_cc_lto_link_modules += ;                                           \
+       $(objtree)/tools/objtool/objtool $(objtool_args) --module $@
+endif
+
+$(obj)/%.lto.o: $(obj)/%.o FORCE
+       $(call if_changed,cc_lto_link_modules)
+endif
+
 cmd_mod = { \
        echo $(if $($*-objs)$($*-y)$($*-m), $(addprefix $(obj)/, $($*-objs) $($*-y) $($*-m)), $(@:.mod=.o)); \
        $(undefined_syms) echo; \
        } > $@
 
-$(obj)/%.mod: $(obj)/%.o FORCE
+$(obj)/%.mod: $(obj)/%$(mod-prelink-ext).o FORCE
        $(call if_changed,mod)
 
 quiet_cmd_cc_lst_c = MKLST   $@