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authorSami Tolvanen <samitolvanen@google.com>2021-08-16 11:05:19 -0700
committerMasahiro Yamada <masahiroy@kernel.org>2021-09-03 08:12:39 +0900
commit850ded46c64299f04d15e39caaba21963fb966f8 (patch)
tree782ee2114059886c099257096c2ede2623ad0b1e /scripts/Makefile.modpost
parent7d73c3e9c51400d3e0e755488050804e4d44737a (diff)
kbuild: Fix TRIM_UNUSED_KSYMS with LTO_CLANG
With CONFIG_LTO_CLANG, we currently link modules into native code just before modpost, which means with TRIM_UNUSED_KSYMS enabled, we still look at the LLVM bitcode in the .o files when generating the list of used symbols. As the bitcode doesn't yet have calls to compiler intrinsics and llvm-nm doesn't see function references that only exist in function-level inline assembly, we currently need a whitelist for TRIM_UNUSED_KSYMS to work with LTO. This change moves module LTO linking to happen earlier, and thus avoids the issue with LLVM bitcode and TRIM_UNUSED_KSYMS entirely, allowing us to also drop the whitelist from gen_autoksyms.sh. Link: https://github.com/ClangBuiltLinux/linux/issues/1369 Signed-off-by: Sami Tolvanen <samitolvanen@google.com> Reviewed-by: Alexander Lobakin <alobakin@pm.me> Tested-by: Alexander Lobakin <alobakin@pm.me> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Diffstat (limited to 'scripts/Makefile.modpost')
-rw-r--r--scripts/Makefile.modpost22
1 files changed, 3 insertions, 19 deletions
diff --git a/scripts/Makefile.modpost b/scripts/Makefile.modpost
index c383ba33d837..eef56d629799 100644
--- a/scripts/Makefile.modpost
+++ b/scripts/Makefile.modpost
@@ -41,7 +41,7 @@ __modpost:
include include/config/auto.conf
include $(srctree)/scripts/Kbuild.include
-# for ld_flags
+# for mod-prelink-ext
include $(srctree)/scripts/Makefile.lib
MODPOST = scripts/mod/modpost \
@@ -118,22 +118,6 @@ $(input-symdump):
@echo >&2 ' Modules may not have dependencies or modversions.'
@echo >&2 ' You may get many unresolved symbol warnings.'
-ifdef CONFIG_LTO_CLANG
-# With CONFIG_LTO_CLANG, .o files might be LLVM bitcode, so we need to run
-# LTO to compile them into native code before running modpost
-prelink-ext := .lto
-
-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 $^
-
-%.lto.o: %.o
- $(call if_changed,cc_lto_link_modules)
-endif
-
modules := $(sort $(shell cat $(MODORDER)))
# KBUILD_MODPOST_WARN can be set to avoid error out in case of undefined symbols
@@ -144,9 +128,9 @@ endif
# Read out modules.order to pass in modpost.
# Otherwise, allmodconfig would fail with "Argument list too long".
quiet_cmd_modpost = MODPOST $@
- cmd_modpost = sed 's/\.ko$$/$(prelink-ext)\.o/' $< | $(MODPOST) -T -
+ cmd_modpost = sed 's/\.ko$$/$(mod-prelink-ext)\.o/' $< | $(MODPOST) -T -
-$(output-symdump): $(MODORDER) $(input-symdump) $(modules:.ko=$(prelink-ext).o) FORCE
+$(output-symdump): $(MODORDER) $(input-symdump) $(modules:.ko=$(mod-prelink-ext).o) FORCE
$(call if_changed,modpost)
targets += $(output-symdump)