[PATCH v3 02/28] kbuild: Add CONFIG_OBJTOOL_DEFERRED
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COLD19d
From: Josh Poimboeuf <jpoimboe@kernel.org>
Date: 2026-09-21 22:31:37
Also in:
linux-kbuild, lkml
Subsystem:
kernel build + files below scripts/ (unless maintained elsewhere), library code, the rest, x86 architecture (32-bit and 64-bit) · Maintainers:
Nathan Chancellor, Nicolas Schier, Andrew Morton, Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen
Revision v3 of 3 in this series.
Revisions (3)
- v1 [diff vs current]
- v2 [diff vs current]
- v3 current
For LTO, IBT, and KLP builds, the running of objtool is deferred to vmlinux.o rather than individual translation units. In preparation for deferring it in more cases, add a new config option. No functional change. Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> --- arch/x86/boot/startup/Makefile | 2 +- lib/Kconfig.debug | 7 +++++++ scripts/Makefile.build | 4 ++-- scripts/Makefile.lib | 4 +--- scripts/Makefile.vmlinux_o | 13 +++++++------ scripts/link-vmlinux.sh | 3 +-- 6 files changed, 19 insertions(+), 14 deletions(-)
diff --git a/arch/x86/boot/startup/Makefile b/arch/x86/boot/startup/Makefile
index 5e499cfb29b5c..ab6e9970d4f4e 100644
--- a/arch/x86/boot/startup/Makefile
+++ b/arch/x86/boot/startup/Makefile@@ -36,7 +36,7 @@ $(patsubst %.o,$(obj)/%.o,$(lib-y)): OBJECT_FILES_NON_STANDARD := y # relocations, even if other objtool actions are being deferred. # $(pi-objs): objtool-enabled = 1 -$(pi-objs): objtool-args = $(if $(delay-objtool),--dry-run,$(objtool-args-y)) --noabs +$(pi-objs): objtool-args = $(if $(CONFIG_OBJTOOL_DEFERRED),--dry-run,$(objtool-args-y)) --noabs # # Confine the startup code by prefixing all symbols with __pi_ (for position
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 134b15a44625e..55732323dc16e 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug@@ -570,6 +570,13 @@ config OBJTOOL_WERROR If unsure, say Y. +# For when objtool defers its work to the linked image (vmlinux.o or module.o) +# rather than running on individual translation units. +config OBJTOOL_DEFERRED + def_bool y + depends on OBJTOOL + depends on LTO_CLANG || X86_KERNEL_IBT || KLP_BUILD + config STACK_VALIDATION bool "Compile-time stack metadata validation" depends on HAVE_STACK_VALIDATION && UNWINDER_FRAME_POINTER
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 4349108e75e1f..87993362595ce 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build@@ -278,7 +278,7 @@ endif # CONFIG_FTRACE_MCOUNT_USE_RECORDMCOUNT is-standard-object = $(if $(filter-out y%, $(OBJECT_FILES_NON_STANDARD_$(target-stem).o)$(OBJECT_FILES_NON_STANDARD)n),$(is-kernel-object)) ifdef CONFIG_OBJTOOL -$(obj)/%.o: private objtool-enabled = $(if $(is-standard-object),$(if $(delay-objtool),$(is-single-obj-m),y)) +$(obj)/%.o: private objtool-enabled = $(if $(is-standard-object),$(if $(CONFIG_OBJTOOL_DEFERRED),$(is-single-obj-m),y)) endif ifneq ($(findstring 1, $(KBUILD_EXTRA_WARN)),)
@@ -504,7 +504,7 @@ define rule_ld_multi_m $(call cmd,gen_objtooldep) endef -$(multi-obj-m): private objtool-enabled := $(delay-objtool) +$(multi-obj-m): private objtool-enabled := $(CONFIG_OBJTOOL_DEFERRED) $(multi-obj-m): private part-of-module := y $(multi-obj-m): %.o: %.mod FORCE $(call if_changed_rule,ld_multi_m)
diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
index 0a4fdd8bd975d..3622237e41d2e 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib@@ -210,11 +210,9 @@ objtool-args-$(or $(CONFIG_GCOV_KERNEL),$(CONFIG_KCOV)) += --no-unreachable objtool-args-$(CONFIG_OBJTOOL_WERROR) += --werror objtool-args = $(objtool-args-y) \ - $(if $(delay-objtool), --link) \ + $(if $(CONFIG_OBJTOOL_DEFERRED), --link) \ $(if $(part-of-module), --module) -delay-objtool := $(or $(CONFIG_LTO_CLANG),$(CONFIG_X86_KERNEL_IBT),$(CONFIG_KLP_BUILD)) - cmd_objtool = $(if $(objtool-enabled), ; $(objtool) $(objtool-args) $@) cmd_gen_objtooldep = $(if $(objtool-enabled), { echo ; echo '$@: $$(wildcard $(objtool))' ; } >> $(dot-target).cmd)
diff --git a/scripts/Makefile.vmlinux_o b/scripts/Makefile.vmlinux_o
index 24a3a4fd271c2..9bac917e8b819 100644
--- a/scripts/Makefile.vmlinux_o
+++ b/scripts/Makefile.vmlinux_o@@ -30,15 +30,16 @@ endif # objtool for vmlinux.o # --------------------------------------------------------------------------- # -# For delay-objtool (IBT or LTO), objtool doesn't run on individual translation -# units. Instead it runs on vmlinux.o. +# For CONFIG_OBJTOOL_DEFERRED (IBT or LTO), objtool doesn't run on individual +# translation units. Instead it runs on vmlinux.o. # -# For !delay-objtool + CONFIG_NOINSTR_VALIDATION, it runs on both translation -# units and vmlinux.o, with the latter only used for noinstr/unret validation. +# For !CONFIG_OBJTOOL_DEFERRED + CONFIG_NOINSTR_VALIDATION, it runs on both +# translation units and vmlinux.o, with the latter only used for noinstr/unret +# validation. -objtool-enabled := $(or $(delay-objtool),$(CONFIG_NOINSTR_VALIDATION)) +objtool-enabled := $(or $(CONFIG_OBJTOOL_DEFERRED),$(CONFIG_NOINSTR_VALIDATION)) -ifeq ($(delay-objtool),y) +ifeq ($(CONFIG_OBJTOOL_DEFERRED),y) vmlinux-objtool-args-y += $(objtool-args-y) else vmlinux-objtool-args-$(CONFIG_OBJTOOL_WERROR) += --werror
diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
index ab0b8125c8cbc..07ba4360b2c89 100755
--- a/scripts/link-vmlinux.sh
+++ b/scripts/link-vmlinux.sh@@ -60,8 +60,7 @@ vmlinux_link() # skip output file argument shift - if is_enabled CONFIG_LTO_CLANG || is_enabled CONFIG_X86_KERNEL_IBT || - is_enabled CONFIG_KLP_BUILD; then + if is_enabled CONFIG_OBJTOOL_DEFERRED || is_enabled CONFIG_LTO_CLANG; then # Use vmlinux.o instead of performing the slow LTO link again. objs=vmlinux.o libs=
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2.55.0