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author | Sami Tolvanen <samitolvanen@google.com> | 2021-02-23 13:59:52 -0800 |
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committer | Kees Cook <keescook@chromium.org> | 2021-02-23 14:10:44 -0800 |
commit | 5e95325fbbbdea96de91e7bdb05fe95a3031e37d (patch) | |
tree | 20a72533b15f1fac23f09b881d1e3ec63c1f2a31 /Makefile | |
parent | b33fff07e3e3817d94dbec7bf2040070ecd96d16 (diff) | |
download | linux-5e95325fbbbdea96de91e7bdb05fe95a3031e37d.tar.gz |
kbuild: lto: force rebuilds when switching CONFIG_LTO
When doing non-clean builds and switching between CONFIG_LTO=n and CONFIG_LTO=y, the build system (correctly) didn't notice that assembly and LTO-excluded C object files were rewritten in place by objtool (to add the .orc_unwind* sections), since their build command lines were the same between CONFIG_LTO=y and CONFIG_LTO=n. The objtool step would fail: vmlinux.o: warning: objtool: file already has .orc_unwind section, skipping make: *** [Makefile:1194: vmlinux] Error 255 Avoid this by making sure the build will see a difference between an LTO and non-LTO build (by including "-fno-lto" in KBUILD_*FLAGS). This will get ignored when CC_FLAGS_LTO is present, and will not be included at all when CONFIG_LTO=n. Signed-off-by: Sami Tolvanen <samitolvanen@google.com> Signed-off-by: Kees Cook <keescook@chromium.org>
Diffstat (limited to 'Makefile')
-rw-r--r-- | Makefile | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/Makefile b/Makefile index 3189eacf3185..639873def1fd 100644 --- a/Makefile +++ b/Makefile @@ -910,7 +910,8 @@ KBUILD_LDFLAGS += -mllvm -import-instr-limit=5 endif ifdef CONFIG_LTO -KBUILD_CFLAGS += $(CC_FLAGS_LTO) +KBUILD_CFLAGS += -fno-lto $(CC_FLAGS_LTO) +KBUILD_AFLAGS += -fno-lto export CC_FLAGS_LTO endif |