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| author | Sami Tolvanen <samitolvanen@google.com> | 2020-04-13 16:10:13 -0700 |
|---|---|---|
| committer | Kees Cook <keescook@chromium.org> | 2021-02-23 12:46:57 -0800 |
| commit | b1a1a1a09b4606d41723a426110382d2077c26fb (patch) | |
| tree | 4c6672f8aa90443585f2ceb4cb4e65425d800c6a /scripts/Makefile.lib | |
| parent | 41425ebe20245c99b44d6ba0f017be9bfc28414f (diff) | |
| download | lwn-b1a1a1a09b4606d41723a426110382d2077c26fb.tar.gz lwn-b1a1a1a09b4606d41723a426110382d2077c26fb.zip | |
kbuild: lto: postpone objtool
With LTO, LLVM bitcode won't be compiled into native code until
modpost_link, or modfinal for modules. This change postpones calls
to objtool until after these steps, and moves objtool_args to
Makefile.lib, so the arguments can be reused in Makefile.modfinal.
As we didn't have objects to process earlier, we use --duplicate
when processing vmlinux.o. This change also disables unreachable
instruction warnings with LTO to avoid warnings about the int3
padding between functions.
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Diffstat (limited to 'scripts/Makefile.lib')
| -rw-r--r-- | scripts/Makefile.lib | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib index 3ff3dbb3a830..6d004143c4d7 100644 --- a/scripts/Makefile.lib +++ b/scripts/Makefile.lib @@ -220,6 +220,18 @@ dtc_cpp_flags = -Wp,-MMD,$(depfile).pre.tmp -nostdinc \ $(addprefix -I,$(DTC_INCLUDE)) \ -undef -D__DTS__ +# Objtool arguments are also needed for modfinal with LTO, so we define +# then here to avoid duplication. +objtool_args = \ + $(if $(CONFIG_UNWINDER_ORC),orc generate,check) \ + $(if $(part-of-module), --module,) \ + $(if $(CONFIG_FRAME_POINTER),, --no-fp) \ + $(if $(or $(CONFIG_GCOV_KERNEL),$(CONFIG_LTO_CLANG)), \ + --no-unreachable,) \ + $(if $(CONFIG_RETPOLINE), --retpoline,) \ + $(if $(CONFIG_X86_SMAP), --uaccess,) \ + $(if $(CONFIG_FTRACE_MCOUNT_USE_OBJTOOL), --mcount,) + # Useful for describing the dependency of composite objects # Usage: # $(call multi_depend, multi_used_targets, suffix_to_remove, suffix_to_add) |