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authorSami Tolvanen <samitolvanen@google.com>2020-04-13 16:10:13 -0700
committerKees Cook <keescook@chromium.org>2021-02-23 12:46:57 -0800
commitb1a1a1a09b4606d41723a426110382d2077c26fb (patch)
tree4c6672f8aa90443585f2ceb4cb4e65425d800c6a /scripts/Makefile.modfinal
parent41425ebe20245c99b44d6ba0f017be9bfc28414f (diff)
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.modfinal')
-rw-r--r--scripts/Makefile.modfinal19
1 files changed, 16 insertions, 3 deletions
diff --git a/scripts/Makefile.modfinal b/scripts/Makefile.modfinal
index 6de2c35b64e8..735e11e9041b 100644
--- a/scripts/Makefile.modfinal
+++ b/scripts/Makefile.modfinal
@@ -9,7 +9,7 @@ __modfinal:
include include/config/auto.conf
include $(srctree)/scripts/Kbuild.include
-# for c_flags
+# for c_flags and objtool_args
include $(srctree)/scripts/Makefile.lib
# find all modules listed in modules.order
@@ -34,10 +34,23 @@ ifdef CONFIG_LTO_CLANG
# With CONFIG_LTO_CLANG, reuse the object file we compiled for modpost to
# avoid a second slow LTO link
prelink-ext := .lto
-endif
+
+# ELF processing was skipped earlier because we didn't have native code,
+# so let's now process the prelinked binary before we link the module.
+
+ifdef CONFIG_STACK_VALIDATION
+ifneq ($(SKIP_STACK_VALIDATION),1)
+cmd_ld_ko_o += \
+ $(objtree)/tools/objtool/objtool $(objtool_args) \
+ $(@:.ko=$(prelink-ext).o);
+
+endif # SKIP_STACK_VALIDATION
+endif # CONFIG_STACK_VALIDATION
+
+endif # CONFIG_LTO_CLANG
quiet_cmd_ld_ko_o = LD [M] $@
- cmd_ld_ko_o = \
+ cmd_ld_ko_o += \
$(LD) -r $(KBUILD_LDFLAGS) \
$(KBUILD_LDFLAGS_MODULE) $(LDFLAGS_MODULE) \
-T scripts/module.lds -o $@ $(filter %.o, $^); \