objtool: Detect and warn if libelf is missing and don't break the build (3b27a0c8) · Commits · 戴 / test

With CONFIG_STACK_VALIDATION enabled, if the host system doesn't have a development version of libelf installed, the build fails with errors like: elf.h:22:18: fatal error: gelf.h: No such file or directory compilation terminated. Instead of failing to build, instead just print a warning and disable stack validation. Signed-off-by:

Josh Poimboeuf <jpoimboe@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Sudip Mukherjee <sudipm.mukherjee@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-next@vger.kernel.org Cc: linux@roeck-us.net Cc: live-patching@vger.kernel.org Link: http://lkml.kernel.org/r/8c27fe00face60f42e888ddb3142c97e45223165.1457026550.git.jpoimboe@redhat.com Signed-off-by:

Ingo Molnar <mingo@kernel.org>

Makefile

+12 −1

Original line number	Diff line number	Diff line
		@@ -995,8 +995,19 @@ prepare0: archprepare FORCE
		# All the preparing..
		prepare: prepare0 prepare-objtool

		ifdef CONFIG_STACK_VALIDATION
		has_libelf := $(shell echo "int main() {}" \| $(HOSTCC) -xc -o /dev/null -lelf - &> /dev/null && echo 1 \|\| echo 0)
		ifeq ($(has_libelf),1)
		objtool_target := tools/objtool FORCE
		else
		$(warning "Cannot use CONFIG_STACK_VALIDATION, please install libelf-dev or elfutils-libelf-devel")
		SKIP_STACK_VALIDATION := 1
		export SKIP_STACK_VALIDATION
		endif
		endif

		PHONY += prepare-objtool
		prepare-objtool: $(if $(CONFIG_STACK_VALIDATION), tools/objtool FORCE)
		prepare-objtool: $(objtool_target)

		# Generate some files
		# ---------------------------------------------------------------------------

scripts/Makefile.build

+2 −0

Original line number	Diff line number	Diff line
		@@ -242,6 +242,7 @@ cmd_record_mcount = \
		endif

		ifdef CONFIG_STACK_VALIDATION
		ifneq ($(SKIP_STACK_VALIDATION),1)

		__objtool_obj := $(objtree)/tools/objtool/objtool

		@@ -260,6 +261,7 @@ objtool_obj = $(if $(patsubst y%,, \
		$(OBJECT_FILES_NON_STANDARD_$(basetarget).o)$(OBJECT_FILES_NON_STANDARD)n), \
		$(__objtool_obj))

		endif # SKIP_STACK_VALIDATION
		endif # CONFIG_STACK_VALIDATION

		define rule_cc_o_c

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