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>
This commit is contained in:
Sami Tolvanen
Kees Cook
parent
41425ebe20
commit
b1a1a1a09b
|
|
@ -218,30 +218,11 @@ cmd_record_mcount = $(if $(findstring $(strip $(CC_FLAGS_FTRACE)),$(_c_flags)),
|
|||
endif # CONFIG_FTRACE_MCOUNT_USE_RECORDMCOUNT
|
||||
|
||||
ifdef CONFIG_STACK_VALIDATION
|
||||
ifndef CONFIG_LTO_CLANG
|
||||
ifneq ($(SKIP_STACK_VALIDATION),1)
|
||||
|
||||
__objtool_obj := $(objtree)/tools/objtool/objtool
|
||||
|
||||
objtool_args = $(if $(CONFIG_UNWINDER_ORC),orc generate,check)
|
||||
|
||||
objtool_args += $(if $(part-of-module), --module,)
|
||||
|
||||
ifndef CONFIG_FRAME_POINTER
|
||||
objtool_args += --no-fp
|
||||
endif
|
||||
ifdef CONFIG_GCOV_KERNEL
|
||||
objtool_args += --no-unreachable
|
||||
endif
|
||||
ifdef CONFIG_RETPOLINE
|
||||
objtool_args += --retpoline
|
||||
endif
|
||||
ifdef CONFIG_X86_SMAP
|
||||
objtool_args += --uaccess
|
||||
endif
|
||||
ifdef CONFIG_FTRACE_MCOUNT_USE_OBJTOOL
|
||||
objtool_args += --mcount
|
||||
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
|
||||
|
|
@ -253,6 +234,7 @@ objtool_obj = $(if $(patsubst y%,, \
|
|||
$(__objtool_obj))
|
||||
|
||||
endif # SKIP_STACK_VALIDATION
|
||||
endif # CONFIG_LTO_CLANG
|
||||
endif # CONFIG_STACK_VALIDATION
|
||||
|
||||
# Rebuild all objects when objtool changes, or is enabled/disabled.
|
||||
|
|
|
|||
|
|
@ -220,6 +220,18 @@ dtc_cpp_flags = -Wp,-MMD,$(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)
|
||||
|
|
|
|||
|
|
@ -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, $^); \
|
||||
|
|
|
|||
|
|
@ -103,14 +103,36 @@ modpost_link()
|
|||
|
||||
objtool_link()
|
||||
{
|
||||
local objtoolcmd;
|
||||
local objtoolopt;
|
||||
|
||||
if [ "${CONFIG_LTO_CLANG} ${CONFIG_STACK_VALIDATION}" = "y y" ]; then
|
||||
# Don't perform vmlinux validation unless explicitly requested,
|
||||
# but run objtool on vmlinux.o now that we have an object file.
|
||||
if [ -n "${CONFIG_UNWINDER_ORC}" ]; then
|
||||
objtoolcmd="orc generate"
|
||||
fi
|
||||
|
||||
objtoolopt="${objtoolopt} --duplicate"
|
||||
|
||||
if [ -n "${CONFIG_FTRACE_MCOUNT_USE_OBJTOOL}" ]; then
|
||||
objtoolopt="${objtoolopt} --mcount"
|
||||
fi
|
||||
fi
|
||||
|
||||
if [ -n "${CONFIG_VMLINUX_VALIDATION}" ]; then
|
||||
objtoolopt="check --vmlinux --noinstr"
|
||||
objtoolopt="${objtoolopt} --noinstr"
|
||||
fi
|
||||
|
||||
if [ -n "${objtoolopt}" ]; then
|
||||
if [ -z "${objtoolcmd}" ]; then
|
||||
objtoolcmd="check"
|
||||
fi
|
||||
objtoolopt="${objtoolopt} --vmlinux"
|
||||
if [ -z "${CONFIG_FRAME_POINTER}" ]; then
|
||||
objtoolopt="${objtoolopt} --no-fp"
|
||||
fi
|
||||
if [ -n "${CONFIG_GCOV_KERNEL}" ]; then
|
||||
if [ -n "${CONFIG_GCOV_KERNEL}" ] || [ -n "${CONFIG_LTO_CLANG}" ]; then
|
||||
objtoolopt="${objtoolopt} --no-unreachable"
|
||||
fi
|
||||
if [ -n "${CONFIG_RETPOLINE}" ]; then
|
||||
|
|
@ -120,7 +142,7 @@ objtool_link()
|
|||
objtoolopt="${objtoolopt} --uaccess"
|
||||
fi
|
||||
info OBJTOOL ${1}
|
||||
tools/objtool/objtool ${objtoolopt} ${1}
|
||||
tools/objtool/objtool ${objtoolcmd} ${objtoolopt} ${1}
|
||||
fi
|
||||
}
|
||||
|
||||
|
|
|
|||
Loading…
Reference in New Issue