objtool: Add CONFIG_STACK_VALIDATION option
Add a CONFIG_STACK_VALIDATION option which will run "objtool check" for
each .o file to ensure the validity of its stack metadata.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Bernd Petrovitsch <bernd@petrovitsch.priv.at>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Chris J Arges <chris.j.arges@canonical.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michal Marek <mmarek@suse.cz>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Pedro Alves <palves@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: live-patching@vger.kernel.org
Link: http://lkml.kernel.org/r/92baab69a6bf9bc7043af0bfca9fb964a1d45546.1456719558.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
diff --git a/Makefile b/Makefile
index fbe1b92..62be03b 100644
--- a/Makefile
+++ b/Makefile
@@ -993,7 +993,10 @@
$(Q)$(MAKE) $(build)=.
# All the preparing..
-prepare: prepare0
+prepare: prepare0 prepare-objtool
+
+PHONY += prepare-objtool
+prepare-objtool: $(if $(CONFIG_STACK_VALIDATION), tools/objtool FORCE)
# Generate some files
# ---------------------------------------------------------------------------
diff --git a/arch/Kconfig b/arch/Kconfig
index f6b649d..81869a5 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -583,6 +583,12 @@
normal C parameter passing, rather than extracting the syscall
argument from pt_regs.
+config HAVE_STACK_VALIDATION
+ bool
+ help
+ Architecture supports the 'objtool check' host tool command, which
+ performs compile-time stack metadata validation.
+
#
# ABI hall of shame
#
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 8bfd1ac..8552656 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -342,6 +342,18 @@
larger and slower, but it gives very useful debugging information
in case of kernel bugs. (precise oopses/stacktraces/warnings)
+config STACK_VALIDATION
+ bool "Compile-time stack metadata validation"
+ depends on HAVE_STACK_VALIDATION
+ default n
+ help
+ Add compile-time checks to validate stack metadata, including frame
+ pointers (if CONFIG_FRAME_POINTER is enabled). This helps ensure
+ that runtime stack traces are more reliable.
+
+ For more information, see
+ tools/objtool/Documentation/stack-validation.txt.
+
config DEBUG_FORCE_WEAK_PER_CPU
bool "Force weak per-cpu definitions"
depends on DEBUG_KERNEL
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 2c47f9c..130a452 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -241,10 +241,32 @@
fi;
endif
+ifdef CONFIG_STACK_VALIDATION
+
+__objtool_obj := $(objtree)/tools/objtool/objtool
+
+objtool_args = check
+ifndef CONFIG_FRAME_POINTER
+objtool_args += --no-fp
+endif
+
+# 'OBJECT_FILES_NON_STANDARD := y': skip objtool checking for a directory
+# 'OBJECT_FILES_NON_STANDARD_foo.o := 'y': skip objtool checking for a file
+# 'OBJECT_FILES_NON_STANDARD_foo.o := 'n': override directory skip for a file
+cmd_objtool = $(if $(patsubst y%,, \
+ $(OBJECT_FILES_NON_STANDARD_$(basetarget).o)$(OBJECT_FILES_NON_STANDARD)n), \
+ $(__objtool_obj) $(objtool_args) "$(@)";)
+objtool_obj = $(if $(patsubst y%,, \
+ $(OBJECT_FILES_NON_STANDARD_$(basetarget).o)$(OBJECT_FILES_NON_STANDARD)n), \
+ $(__objtool_obj))
+
+endif # CONFIG_STACK_VALIDATION
+
define rule_cc_o_c
$(call echo-cmd,checksrc) $(cmd_checksrc) \
$(call echo-cmd,cc_o_c) $(cmd_cc_o_c); \
$(cmd_modversions) \
+ $(cmd_objtool) \
$(call echo-cmd,record_mcount) \
$(cmd_record_mcount) \
scripts/basic/fixdep $(depfile) $@ '$(call make-cmd,cc_o_c)' > \
@@ -253,14 +275,23 @@
mv -f $(dot-target).tmp $(dot-target).cmd
endef
+define rule_as_o_S
+ $(call echo-cmd,as_o_S) $(cmd_as_o_S); \
+ $(cmd_objtool) \
+ scripts/basic/fixdep $(depfile) $@ '$(call make-cmd,as_o_S)' > \
+ $(dot-target).tmp; \
+ rm -f $(depfile); \
+ mv -f $(dot-target).tmp $(dot-target).cmd
+endef
+
# Built-in and composite module parts
-$(obj)/%.o: $(src)/%.c $(recordmcount_source) FORCE
+$(obj)/%.o: $(src)/%.c $(recordmcount_source) $(objtool_obj) FORCE
$(call cmd,force_checksrc)
$(call if_changed_rule,cc_o_c)
# Single-part modules are special since we need to mark them in $(MODVERDIR)
-$(single-used-m): $(obj)/%.o: $(src)/%.c $(recordmcount_source) FORCE
+$(single-used-m): $(obj)/%.o: $(src)/%.c $(recordmcount_source) $(objtool_obj) FORCE
$(call cmd,force_checksrc)
$(call if_changed_rule,cc_o_c)
@{ echo $(@:.o=.ko); echo $@; } > $(MODVERDIR)/$(@F:.o=.mod)
@@ -290,8 +321,8 @@
quiet_cmd_as_o_S = AS $(quiet_modtag) $@
cmd_as_o_S = $(CC) $(a_flags) -c -o $@ $<
-$(obj)/%.o: $(src)/%.S FORCE
- $(call if_changed_dep,as_o_S)
+$(obj)/%.o: $(src)/%.S $(objtool_obj) FORCE
+ $(call if_changed_rule,as_o_S)
targets += $(real-objs-y) $(real-objs-m) $(lib-y)
targets += $(extra-y) $(MAKECMDGOALS) $(always)