From 3b27a0c85d7068130ed8e3977a2e977ade986841 Mon Sep 17 00:00:00 2001 From: Josh Poimboeuf Date: Thu, 3 Mar 2016 11:39:30 -0600 Subject: [PATCH] objtool: Detect and warn if libelf is missing and don't break the build 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 Cc: Andrew Morton Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Stephen Rothwell Cc: Sudip Mukherjee Cc: Thomas Gleixner 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 --- Makefile | 13 ++++++++++++- scripts/Makefile.build | 2 ++ 2 files changed, 14 insertions(+), 1 deletion(-) diff --git a/Makefile b/Makefile index 2c27a01c42f1..60b729540785 100644 --- a/Makefile +++ b/Makefile @@ -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: $(objtool_target) # Generate some files # --------------------------------------------------------------------------- diff --git a/scripts/Makefile.build b/scripts/Makefile.build index 130a452d42ee..e1bc1907090e 100644 --- a/scripts/Makefile.build +++ b/scripts/Makefile.build @@ -242,6 +242,7 @@ cmd_record_mcount = \ endif ifdef CONFIG_STACK_VALIDATION +ifneq ($(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