x86/build: Get rid of vmlinux postlink step

PATCH In review Ard Biesheuvel 9 participants 19 messages Mar 11, 2025 – Apr 30, 2025

Subsystems (6)

x86 Kbuild Linux-next tree MIPS +2 more subsystems

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Ard Biesheuvel

author

2025-03-11 11:06 UTC #0 lore raw

v2 cover x86/build: Get rid of vmlinux postlink step

From: Ard Biesheuvel <[email protected]>

Kbuild supports an architecture specific Makefile.postlink file that is invoked for the vmlinux target after it has been built. This Makefile takes 'vmlinux' (which has just been built) as the target, and mangles the file and/or constructs other intermediate artifacts from it.

This violates the general philosophy of Make, which is based on rules and dependencies, and artifacts that are rebuilt only when any of their dependencies have been updated.

Instead, the different incarnations of vmlinux that are consumed by different stages of the build should be emitted as distinct files, where rules and dependencies are used to define one in terms of the other.

This also works around an error observed here [0], where vmlinux is deleted by Make because a subsequent step that consumes it as input throws an error.

So refactor the vmlinux shell scripts and build rules so that architectures that rely on --emit-relocs to construct vmlinux with static relocations preserved will get a separate vmlinux.unstripped file carrying those relocations. This removes the need for an imperative postlink step, given that any rules that depend on the unstripped vmlinux can now simply depend on vmlinux.unstripped, rather than inject a build step into Makefile.postlink

S390 should be able to do the same. MIPS and RISC-V perform some post-build checks on vmlinux, which is reasonable in principle for a postlink step, although deleting vmlinux when the check fails is equally unhelpful.

Changes since v1:
- add vmlinux.unstripped to .gitignore and to the 'clean' target
- move cmd_strip_relocs into Makefile.vmlinux

[0] https://lore.kernel.org/all/[email protected]/T/#m731ed0206949fc3f39fcc8a7b82fe348a8fc80c4

Cc Masahiro Yamada <[email protected]>

Cc Ingo Molnar <[email protected]>

Ard Biesheuvel (4):
Kbuild/link-vmlinux.sh: Make output file name configurable
Kbuild: Introduce Kconfig symbol for linking vmlinux with relocations
Kbuild: Create intermediate vmlinux build with relocations preserved
x86: Get rid of Makefile.postlink

 .gitignore                        |  1 +
 Makefile                          |  6 ++-
 arch/Kconfig                      |  7 ++++
 arch/mips/Kconfig                 |  1 +
 arch/mips/Makefile                |  4 --
 arch/mips/Makefile.postlink       |  2 +-
 arch/riscv/Kconfig                |  1 +
 arch/riscv/Makefile               |  2 +-
 arch/riscv/Makefile.postlink      | 11 +-----
 arch/riscv/boot/Makefile          |  5 +--
 arch/s390/Kconfig                 |  1 +
 arch/s390/Makefile                |  2 +-
 arch/s390/Makefile.postlink       |  4 +-
 arch/x86/Kconfig                  |  1 +
 arch/x86/Makefile                 |  6 ---
 arch/x86/Makefile.postlink        | 40 --------------------
 arch/x86/boot/compressed/Makefile |  9 +++--
 scripts/Makefile.lib              |  3 --
 scripts/Makefile.vmlinux          | 30 +++++++++++----
 scripts/link-vmlinux.sh           | 11 +++---
 20 files changed, 57 insertions(+), 90 deletions(-)
 delete mode 100644 arch/x86/Makefile.postlink

Signature · 1 line

2.49.0.rc0.332.g42c0ae87b1-goog

Ard Biesheuvel

author

2025-03-11 11:06 UTC #1 lore raw

PATCH v2 1/4 Kbuild/link-vmlinux.sh: Make output file name configurable

From: Ard Biesheuvel <[email protected]>

In order to introduce an intermediate, non-stripped vmlinux build that can be used by other build steps as an input, pass the output file name to link-vmlinux.sh via its command line.

Signed-off-by Ard Biesheuvel <[email protected]>

---
 scripts/Makefile.vmlinux |  2 +-
 scripts/link-vmlinux.sh  | 11 ++++++-----
 2 files changed, 7 insertions(+), 6 deletions(-)

scripts/Makefile.vmlinux +1 -1

index 873caaa55313..3523ce3ce3dc 100644
@@ -69,7 +69,7 @@ ARCH_POSTLINK := $(wildcard $(srctree)/arch/$(SRCARCH)/Makefile.postlink)
 
 # Final link of vmlinux with optional arch pass after final link
 cmd_link_vmlinux =							\
-	$< "$(LD)" "$(KBUILD_LDFLAGS)" "$(LDFLAGS_vmlinux)";		\
+	$< "$(LD)" "$(KBUILD_LDFLAGS)" "$(LDFLAGS_vmlinux)" "$@";	\
 	$(if $(ARCH_POSTLINK), $(MAKE) -f $(ARCH_POSTLINK) $@, true)
 
 targets += vmlinux

scripts/link-vmlinux.sh +6 -5

index 56a077d204cf..e55026128e05 100755
@@ -31,6 +31,7 @@ set -e
 LD="$1"
 KBUILD_LDFLAGS="$2"
 LDFLAGS_vmlinux="$3"
+VMLINUX="$4"
 
 is_enabled() {
 	grep -q "^$1=y" include/config/auto.conf

@@ -278,7 +279,7 @@ fi
 
 strip_debug=
 
-vmlinux_link vmlinux
+vmlinux_link "${VMLINUX}"
 
 # fill in BTF IDs
 if is_enabled CONFIG_DEBUG_INFO_BTF; then

@@ -290,11 +291,11 @@ if is_enabled CONFIG_DEBUG_INFO_BTF; then
 	${RESOLVE_BTFIDS} ${RESOLVE_BTFIDS_ARGS} vmlinux
 fi
 
-mksysmap vmlinux System.map
+mksysmap "${VMLINUX}" System.map
 
 if is_enabled CONFIG_BUILDTIME_TABLE_SORT; then
-	info SORTTAB vmlinux
-	if ! sorttable vmlinux; then
+	info SORTTAB "${VMLINUX}"
+	if ! sorttable "${VMLINUX}"; then
 		echo >&2 Failed to sort kernel tables
 		exit 1
 	fi

@@ -310,4 +311,4 @@ if is_enabled CONFIG_KALLSYMS; then
 fi
 
 # For fixdep
-echo "vmlinux: $0" > .vmlinux.d
+echo "${VMLINUX}: $0" > ".${VMLINUX}.d"

Signature · 1 line

2.49.0.rc0.332.g42c0ae87b1-goog

Ard Biesheuvel

author

2025-03-11 11:06 UTC #2 lore raw

PATCH v2 2/4 Kbuild: Introduce Kconfig symbol for linking vmlinux with relocations

In reply to Ard Biesheuvel

From: Ard Biesheuvel <[email protected]>

Some architectures build vmlinux with static relocations preserved, but strip them again from the final vmlinux image. Arch specific tools consume these static relocations in order to construct relocation tables for KASLR.

The fact that vmlinux is created, consumed and subsequently updated goes against the typical, declarative paradigm used by Make, which is based on rules and dependencies. So as a first step towards cleaning this up, introduce a Kconfig symbol to declare that the arch wants to consume the static relocations emitted into vmlinux. This will be wired up further in subsequent patches.

Signed-off-by Ard Biesheuvel <[email protected]>

---
 Makefile            | 4 ++++
 arch/Kconfig        | 7 +++++++
 arch/mips/Kconfig   | 1 +
 arch/mips/Makefile  | 4 ----
 arch/riscv/Kconfig  | 1 +
 arch/riscv/Makefile | 2 +-
 arch/s390/Kconfig   | 1 +
 arch/s390/Makefile  | 2 +-
 arch/x86/Kconfig    | 1 +
 arch/x86/Makefile   | 6 ------
 10 files changed, 17 insertions(+), 12 deletions(-)

Makefile +4 -0

index 30dab4c8b012..a3302dce56de 100644
@@ -1119,6 +1119,10 @@ ifdef CONFIG_LD_ORPHAN_WARN
 LDFLAGS_vmlinux += --orphan-handling=$(CONFIG_LD_ORPHAN_WARN_LEVEL)
 endif
 
+ifneq ($(CONFIG_ARCH_VMLINUX_NEEDS_RELOCS),)
+LDFLAGS_vmlinux	+= --emit-relocs --discard-none
+endif
+
 # Align the bit size of userspace programs with the kernel
 KBUILD_USERCFLAGS  += $(filter -m32 -m64 --target=%, $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS))
 KBUILD_USERLDFLAGS += $(filter -m32 -m64 --target=%, $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS))

arch/Kconfig +7 -0

index b8a4ff365582..101a13fcde8e 100644
@@ -1695,6 +1695,13 @@ config ARCH_HAS_KERNEL_FPU_SUPPORT
 	  Architectures that select this option can run floating-point code in
 	  the kernel, as described in Documentation/core-api/floating-point.rst.
 
+config ARCH_VMLINUX_NEEDS_RELOCS
+	bool
+	help
+	  Whether the architecture needs vmlinux to be built with static
+	  relocations preserved. This is used by some architectures to
+	  construct bespoke relocation tables for KASLR.
+
 source "kernel/gcov/Kconfig"
 
 source "scripts/gcc-plugins/Kconfig"

arch/mips/Kconfig +1 -0

index 1924f2d83932..5aedbd7afadb 100644
@@ -2617,6 +2617,7 @@ config RELOCATABLE
 		   CPU_MIPS32_R6 || CPU_MIPS64_R6 || \
 		   CPU_P5600 || CAVIUM_OCTEON_SOC || \
 		   CPU_LOONGSON64
+	select ARCH_VMLINUX_NEEDS_RELOCS
 	help
 	  This builds a kernel image that retains relocation information
 	  so it can be loaded someplace besides the default 1MB.

arch/mips/Makefile +0 -4

index be8cb44a89fd..d9057e29bc62 100644
@@ -100,10 +100,6 @@ LDFLAGS_vmlinux			+= -G 0 -static -n -nostdlib
 KBUILD_AFLAGS_MODULE		+= -mlong-calls
 KBUILD_CFLAGS_MODULE		+= -mlong-calls
 
-ifeq ($(CONFIG_RELOCATABLE),y)
-LDFLAGS_vmlinux			+= --emit-relocs
-endif
-
 cflags-y += -ffreestanding
 
 cflags-$(CONFIG_CPU_BIG_ENDIAN)		+= -EB

arch/riscv/Kconfig +1 -0

index 7612c52e9b1e..6f5800114416 100644
@@ -1077,6 +1077,7 @@ config RELOCATABLE
 	bool "Build a relocatable kernel"
 	depends on MMU && 64BIT && !XIP_KERNEL
 	select MODULE_SECTIONS if MODULES
+	select ARCH_VMLINUX_NEEDS_RELOCS
 	help
           This builds a kernel as a Position Independent Executable (PIE),
           which retains all relocation metadata required to relocate the

arch/riscv/Makefile +1 -1

index 13fbc0f94238..6ef0d10e0c50 100644
@@ -8,7 +8,7 @@
 
 LDFLAGS_vmlinux := -z norelro
 ifeq ($(CONFIG_RELOCATABLE),y)
-	LDFLAGS_vmlinux += -shared -Bsymbolic -z notext --emit-relocs
+	LDFLAGS_vmlinux += -shared -Bsymbolic -z notext
 	KBUILD_CFLAGS += -fPIE
 endif
 ifeq ($(CONFIG_DYNAMIC_FTRACE),y)

arch/s390/Kconfig +1 -0

index 9c9ec08d78c7..ea67b7317138 100644
@@ -630,6 +630,7 @@ endchoice
 
 config RELOCATABLE
 	def_bool y
+	select ARCH_VMLINUX_NEEDS_RELOCS
 	help
 	  This builds a kernel image that retains relocation information
 	  so it can be loaded at an arbitrary address.

arch/s390/Makefile +1 -1

index 5fae311203c2..d5f4be440879 100644
@@ -15,7 +15,7 @@ KBUILD_CFLAGS_MODULE += -fPIC
 KBUILD_AFLAGS	+= -m64
 KBUILD_CFLAGS	+= -m64
 KBUILD_CFLAGS	+= -fPIC
-LDFLAGS_vmlinux	:= -no-pie --emit-relocs --discard-none
+LDFLAGS_vmlinux	:= -no-pie
 extra_tools	:= relocs
 aflags_dwarf	:= -Wa,-gdwarf-2
 KBUILD_AFLAGS_DECOMPRESSOR := $(CLANG_FLAGS) -m64 -D__ASSEMBLY__

arch/x86/Kconfig +1 -0

index be2c311f5118..2005d80ff8d1 100644
@@ -2199,6 +2199,7 @@ config RANDOMIZE_BASE
 config X86_NEED_RELOCS
 	def_bool y
 	depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
+	select ARCH_VMLINUX_NEEDS_RELOCS
 
 config PHYSICAL_ALIGN
 	hex "Alignment value to which kernel should be aligned"

arch/x86/Makefile +0 -6

index 5b773b34768d..f65ed6dcd6fb 100644
@@ -251,12 +251,6 @@ endif
 
 KBUILD_LDFLAGS += -m elf_$(UTS_MACHINE)
 
-ifdef CONFIG_X86_NEED_RELOCS
-LDFLAGS_vmlinux := --emit-relocs --discard-none
-else
-LDFLAGS_vmlinux :=
-endif
-
 #
 # The 64-bit kernel must be aligned to 2MB.  Pass -z max-page-size=0x200000 to
 # the linker to force 2MB page size regardless of the default page size used

Signature · 1 line

2.49.0.rc0.332.g42c0ae87b1-goog

Ard Biesheuvel

author

2025-03-11 11:06 UTC #3 lore raw

PATCH v2 3/4 Kbuild: Create intermediate vmlinux build with relocations preserved

In reply to Ard Biesheuvel

From: Ard Biesheuvel <[email protected]>

The imperative paradigm used to build vmlinux, extract some info from it or perform some checks on it, and subsequently modify it again goes against the declarative paradigm that is usually employed for defining make rules.

In particular, the Makefile.postlink files that consume their input via an output rule result in some dodgy logic in the decompressor makefiles for RISC-V and x86, given that the vmlinux.relocs input file needed to generate the arch-specific relocation tables may not exist or be out of date, but cannot be constructed using the ordinary Make dependency based rules, because the info needs to be extracted while vmlinux is in its ephemeral, non-stripped form.

So instead, for architectures that require the static relocations that are emitted into vmlinux when passing --emit-relocs to the linker, and are subsequently stripped out again, introduce an intermediate vmlinux target called vmlinux.unstripped, and organize the reset of the build logic accordingly:

- vmlinux.unstripped is created only once, and not updated again
- build rules under arch/*/boot can depend on vmlinux.unstripped without running the risk of the data disappearing or being out of date
- the final vmlinux generated by the build is not bloated with static relocations that are never needed again after the build completes.

Signed-off-by Ard Biesheuvel <[email protected]>

---
 .gitignore                   |  1 +
 Makefile                     |  2 +-
 arch/mips/Makefile.postlink  |  2 +-
 arch/riscv/Makefile.postlink | 11 +-------
 arch/riscv/boot/Makefile     |  5 +---
 arch/s390/Makefile.postlink  |  4 +--
 arch/x86/Makefile.postlink   |  8 +++---
 scripts/Makefile.lib         |  3 ---
 scripts/Makefile.vmlinux     | 28 +++++++++++++++-----
 9 files changed, 30 insertions(+), 34 deletions(-)

.gitignore +1 -0

index 5937c74d3dc1..f2f63e47fb88 100644
@@ -65,6 +65,7 @@ modules.order
 /vmlinux.32
 /vmlinux.map
 /vmlinux.symvers
+/vmlinux.unstripped
 /vmlinux-gdb.py
 /vmlinuz
 /System.map

Makefile +1 -1

index a3302dce56de..c07295a980a0 100644
@@ -1560,7 +1560,7 @@ endif # CONFIG_MODULES
 # Directories & files removed with 'make clean'
 CLEAN_FILES += vmlinux.symvers modules-only.symvers \
 	       modules.builtin modules.builtin.modinfo modules.nsdeps \
-	       modules.builtin.ranges vmlinux.o.map \
+	       modules.builtin.ranges vmlinux.o.map vmlinux.unstripped \
 	       compile_commands.json rust/test \
 	       rust-project.json .vmlinux.objs .vmlinux.export.c \
                .builtin-dtbs-list .builtin-dtb.S

arch/mips/Makefile.postlink +1 -1

index 6cfdc149d3bc..ea0add7d56b2 100644
@@ -22,7 +22,7 @@ quiet_cmd_relocs = RELOCS  $@
 
 # `@true` prevents complaint when there is nothing to be done
 
-vmlinux: FORCE
+vmlinux vmlinux.unstripped: FORCE
 	@true
 ifeq ($(CONFIG_CPU_LOONGSON3_WORKAROUNDS),y)
 	$(call if_changed,ls3_llsc)

arch/riscv/Makefile.postlink +1 ~~-10~~

index 6b0580949b6a..0e4cf8ad2f14 100644
@@ -10,26 +10,17 @@ __archpost:
 
 -include include/config/auto.conf
 include $(srctree)/scripts/Kbuild.include
-include $(srctree)/scripts/Makefile.lib
 
 quiet_cmd_relocs_check = CHKREL  $@
 cmd_relocs_check = 							\
 	$(CONFIG_SHELL) $(srctree)/arch/riscv/tools/relocs_check.sh "$(OBJDUMP)" "$(NM)" "$@"
 
-ifdef CONFIG_RELOCATABLE
-quiet_cmd_cp_vmlinux_relocs = CPREL   vmlinux.relocs
-cmd_cp_vmlinux_relocs = cp vmlinux vmlinux.relocs
-
-endif
-
 # `@true` prevents complaint when there is nothing to be done
 
-vmlinux: FORCE
+vmlinux vmlinux.unstripped: FORCE
 	@true
 ifdef CONFIG_RELOCATABLE
 	$(call if_changed,relocs_check)
-	$(call if_changed,cp_vmlinux_relocs)
-	$(call if_changed,strip_relocs)
 endif
 
 clean:

arch/riscv/boot/Makefile +1 -4

index b25d524ce5eb..bfc3d0b75b9b 100644
@@ -32,10 +32,7 @@ $(obj)/xipImage: vmlinux FORCE
 endif
 
 ifdef CONFIG_RELOCATABLE
-vmlinux.relocs: vmlinux
-	@ (! [ -f vmlinux.relocs ] && echo "vmlinux.relocs can't be found, please remove vmlinux and try again") || true
-
-$(obj)/Image: vmlinux.relocs FORCE
+$(obj)/Image: vmlinux.unstripped FORCE
 else
 $(obj)/Image: vmlinux FORCE
 endif

arch/s390/Makefile.postlink +1 -3

index 1ae5478cd6ac..c2b737500a91 100644
@@ -11,7 +11,6 @@ __archpost:
 
 -include include/config/auto.conf
 include $(srctree)/scripts/Kbuild.include
-include $(srctree)/scripts/Makefile.lib
 
 CMD_RELOCS=arch/s390/tools/relocs
 OUT_RELOCS = arch/s390/boot

@@ -20,9 +19,8 @@ quiet_cmd_relocs = RELOCS  $(OUT_RELOCS)/relocs.S
 	mkdir -p $(OUT_RELOCS); \
 	$(CMD_RELOCS) $@ > $(OUT_RELOCS)/relocs.S
 
-vmlinux: FORCE
+vmlinux.unstripped: FORCE
 	$(call cmd,relocs)
-	$(call cmd,strip_relocs)
 
 clean:
 	@rm -f $(OUT_RELOCS)/relocs.S

arch/x86/Makefile.postlink +3 -5

index 8b8a68162c94..445fce66630f 100644
@@ -11,23 +11,21 @@ __archpost:
 
 -include include/config/auto.conf
 include $(srctree)/scripts/Kbuild.include
-include $(srctree)/scripts/Makefile.lib
 
 CMD_RELOCS = arch/x86/tools/relocs
 OUT_RELOCS = arch/x86/boot/compressed
-quiet_cmd_relocs = RELOCS  $(OUT_RELOCS)/[email protected]
+quiet_cmd_relocs = RELOCS  $(OUT_RELOCS)/vmlinux.relocs
       cmd_relocs = \
 	mkdir -p $(OUT_RELOCS); \
-	$(CMD_RELOCS) $@ > $(OUT_RELOCS)/[email protected]; \
+	$(CMD_RELOCS) $@ > $(OUT_RELOCS)/vmlinux.relocs; \
 	$(CMD_RELOCS) --abs-relocs $@
 
 # `@true` prevents complaint when there is nothing to be done
 
-vmlinux: FORCE
+vmlinux vmlinux.unstripped: FORCE
 	@true
 ifeq ($(CONFIG_X86_NEED_RELOCS),y)
 	$(call cmd,relocs)
-	$(call cmd,strip_relocs)
 endif
 
 clean:

scripts/Makefile.lib +0 -3

index cad20f0e66ee..6abfefd1bd31 100644
@@ -376,9 +376,6 @@ quiet_cmd_ar = AR      $@
 quiet_cmd_objcopy = OBJCOPY $@
 cmd_objcopy = $(OBJCOPY) $(OBJCOPYFLAGS) $(OBJCOPYFLAGS_$(@F)) $< $@
 
-quiet_cmd_strip_relocs = RSTRIP  $@
-cmd_strip_relocs = $(OBJCOPY) --remove-section='.rel*' $@
-
 # Gzip
 # ---------------------------------------------------------------------------

scripts/Makefile.vmlinux +21 -7

index 3523ce3ce3dc..dd744551a896 100644
@@ -9,6 +9,20 @@ include $(srctree)/scripts/Makefile.lib
 
 targets :=
 
+ifdef CONFIG_ARCH_VMLINUX_NEEDS_RELOCS
+vmlinux-final := vmlinux.unstripped
+
+quiet_cmd_strip_relocs = RSTRIP  $@
+      cmd_strip_relocs = $(OBJCOPY) --remove-section='.rel*' $< $@
+
+vmlinux: $(vmlinux-final) FORCE
+	$(call if_changed,strip_relocs)
+
+targets += vmlinux
+else
+vmlinux-final := vmlinux
+endif
+
 %.o: %.c FORCE
 	$(call if_changed_rule,cc_o_c)

@@ -47,7 +61,7 @@ targets += .builtin-dtbs-list
 
 ifdef CONFIG_GENERIC_BUILTIN_DTB
 targets += .builtin-dtbs.S .builtin-dtbs.o
-vmlinux: .builtin-dtbs.o
+$(vmlinux-final): .builtin-dtbs.o
 endif
 
 # vmlinux

@@ -55,11 +69,11 @@ endif
 
 ifdef CONFIG_MODULES
 targets += .vmlinux.export.o
-vmlinux: .vmlinux.export.o
+$(vmlinux-final): .vmlinux.export.o
 endif
 
 ifdef CONFIG_ARCH_WANTS_PRE_LINK_VMLINUX
-vmlinux: arch/$(SRCARCH)/tools/vmlinux.arch.o
+$(vmlinux-final): arch/$(SRCARCH)/tools/vmlinux.arch.o
 
 arch/$(SRCARCH)/tools/vmlinux.arch.o: vmlinux.o FORCE
 	$(Q)$(MAKE) $(build)=arch/$(SRCARCH)/tools $@

@@ -72,11 +86,11 @@ cmd_link_vmlinux =							\
 	$< "$(LD)" "$(KBUILD_LDFLAGS)" "$(LDFLAGS_vmlinux)" "$@";	\
 	$(if $(ARCH_POSTLINK), $(MAKE) -f $(ARCH_POSTLINK) $@, true)
 
-targets += vmlinux
-vmlinux: scripts/link-vmlinux.sh vmlinux.o $(KBUILD_LDS) FORCE
+targets += $(vmlinux-final)
+$(vmlinux-final): scripts/link-vmlinux.sh vmlinux.o $(KBUILD_LDS) FORCE
 	+$(call if_changed_dep,link_vmlinux)
 ifdef CONFIG_DEBUG_INFO_BTF
-vmlinux: $(RESOLVE_BTFIDS)
+$(vmlinux-final): $(RESOLVE_BTFIDS)
 endif
 
 # module.builtin.ranges

@@ -92,7 +106,7 @@ modules.builtin.ranges: $(srctree)/scripts/generate_builtin_ranges.awk \
 			modules.builtin vmlinux.map vmlinux.o.map FORCE
 	$(call if_changed,modules_builtin_ranges)
 
-vmlinux.map: vmlinux
+vmlinux.map: $(vmlinux-final)
 	@:
 
 endif

Signature · 1 line

2.49.0.rc0.332.g42c0ae87b1-goog

kernel test robot

build bot

2025-03-13 09:21 UTC #4 lore raw

Re: [PATCH v2 3/4] Kbuild: Create intermediate vmlinux build with relocations preserved

kernel test robot noticed the following build errors:

Hi Ard,

kernel test robot noticed the following build errors:

[auto build test ERROR on masahiroy-kbuild/for-next]
[also build test ERROR on masahiroy-kbuild/fixes tip/x86/core s390/features linus/master v6.14-rc6 next-20250312] [If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Ard-Biesheuvel/Kbuild-link-vmlinux-sh-Make-output-file-name-configurable/20250311-190926
base:   https://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild.git for-next
patch link:    https://lore.kernel.org/r/20250311110616.148682-9-ardb%2Bgit%40google.com
patch subject: [PATCH v2 3/4] Kbuild: Create intermediate vmlinux build with relocations preserved
config: x86_64-randconfig-076-20250313 (https://download.01.org/0day-ci/archive/20250313/[email protected]/config)
compiler: gcc-12 (Debian 12.2.0-14) 12.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250313/[email protected]/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <[email protected]>
| Closes: https://lore.kernel.org/oe-kbuild-all/[email protected]/

All errors (new ones prefixed by >>):

>> gawk: scripts/generate_builtin_ranges.awk:82: fatal: cannot open file `vmlinux.map' for reading: No such file or directory

Signature · 2 lines

0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

Ard Biesheuvel

2025-03-13 09:34 UTC #5 lore raw

Re: [PATCH v2 3/4] Kbuild: Create intermediate vmlinux build with relocations preserved

Quoted 19 lines · kernel test robot

Hi Ard,
kernel test robot noticed the following build errors:
[auto build test ERROR on masahiroy-kbuild/for-next]
[also build test ERROR on masahiroy-kbuild/fixes tip/x86/core s390/features linus/master v6.14-rc6 next-20250312] [If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]
url:    https://github.com/intel-lab-lkp/linux/commits/Ard-Biesheuvel/Kbuild-link-vmlinux-sh-Make-output-file-name-configurable/20250311-190926
base:   https://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild.git for-next
patch link:    https://lore.kernel.org/r/20250311110616.148682-9-ardb%2Bgit%40google.com
patch subject: [PATCH v2 3/4] Kbuild: Create intermediate vmlinux build with relocations preserved
config: x86_64-randconfig-076-20250313 (https://download.01.org/0day-ci/archive/20250313/[email protected]/config)
compiler: gcc-12 (Debian 12.2.0-14) 12.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250313/[email protected]/reproduce)

Quoted 9 lines

If you fix the issue in a separate patch/commit (i.e. not just a new version of the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <[email protected]>
| Closes: https://lore.kernel.org/oe-kbuild-all/[email protected]/
All errors (new ones prefixed by >>):
Quoted 1 line
Quoted 1 line
gawk: scripts/generate_builtin_ranges.awk:82: fatal: cannot open file `vmlinux.map' for reading: No such file or directory

Hmm it seems I missed some things in link-vmlinux.sh - I will take a look.

Ard Biesheuvel

2025-03-13 10:18 UTC #6 lore raw

Re: [PATCH v2 3/4] Kbuild: Create intermediate vmlinux build with relocations preserved

Quoted 26 lines · Ard Biesheuvel

Quoted 24 lines · kernel test robot
Hi Ard,
kernel test robot noticed the following build errors:
[auto build test ERROR on masahiroy-kbuild/for-next]
[also build test ERROR on masahiroy-kbuild/fixes tip/x86/core s390/features linus/master v6.14-rc6 next-20250312] [If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]
url:    https://github.com/intel-lab-lkp/linux/commits/Ard-Biesheuvel/Kbuild-link-vmlinux-sh-Make-output-file-name-configurable/20250311-190926
base:   https://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild.git for-next
patch link:    https://lore.kernel.org/r/20250311110616.148682-9-ardb%2Bgit%40google.com
patch subject: [PATCH v2 3/4] Kbuild: Create intermediate vmlinux build with relocations preserved
config: x86_64-randconfig-076-20250313 (https://download.01.org/0day-ci/archive/20250313/[email protected]/config)
compiler: gcc-12 (Debian 12.2.0-14) 12.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250313/[email protected]/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <[email protected]>
| Closes: https://lore.kernel.org/oe-kbuild-all/[email protected]/

Quoted 6 lines

Quoted 4 lines
All errors (new ones prefixed by >>):
Quoted 1 line
Quoted 1 line
gawk: scripts/generate_builtin_ranges.awk:82: fatal: cannot open file `vmlinux.map' for reading: No such file or directory
Hmm it seems I missed some things in link-vmlinux.sh - I will take a look.

We'd need something like the below applied on top - shall I send a v3?

scripts/link-vmlinux.sh +7 -6

@@ -46,6 +46,7 @@
 
 # Link of vmlinux
 # ${1} - output file
+# ${2} - map file
 vmlinux_link()
 {
        local output=${1}

@@ -99,7 +100,7 @@ vmlinux_link()
        fi
 
        if is_enabled CONFIG_VMLINUX_MAP; then
-               ldflags="${ldflags} ${wl}-Map=${output}.map"
+               ldflags="${ldflags} ${wl}-Map=${2}"
        fi
 
        ${ld} ${ldflags} -o ${output}                                   \

@@ -185,7 +186,7 @@
 {
        rm -f .btf.*
        rm -f System.map
-       rm -f vmlinux
+       rm -f ${VMLINUX}
        rm -f vmlinux.map
 }

@@ -224,7 +225,7 @@
                strip_debug=1
        fi
 
-       vmlinux_link .tmp_vmlinux1
+       vmlinux_link .tmp_vmlinux1 .tmp_vmlinux1.map
 fi
 
 if is_enabled CONFIG_DEBUG_INFO_BTF; then

@@ -267,19 +268,19 @@
        sysmap_and_kallsyms .tmp_vmlinux1
        size1=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso})
 
-       vmlinux_link .tmp_vmlinux2
+       vmlinux_link .tmp_vmlinux2 .tmp_vmlinux2.map
        sysmap_and_kallsyms .tmp_vmlinux2
        size2=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso})
 
        if [ $size1 -ne $size2 ] || [ -n "${KALLSYMS_EXTRA_PASS}" ]; then
-               vmlinux_link .tmp_vmlinux3
+               vmlinux_link .tmp_vmlinux3 .tmp_vmlinux3.map
                sysmap_and_kallsyms .tmp_vmlinux3
        fi
 fi
 
 strip_debug=
 
-vmlinux_link "${VMLINUX}"
+vmlinux_link "${VMLINUX}" vmlinux.map
 
 # fill in BTF IDs
 if is_enabled CONFIG_DEBUG_INFO_BTF; then

Masahiro Yamada

2025-03-13 10:30 UTC #7 lore raw

Re: [PATCH v2 3/4] Kbuild: Create intermediate vmlinux build with relocations preserved

Quoted 28 lines · Ard Biesheuvel

Quoted 26 lines · Ard Biesheuvel
Quoted 24 lines · kernel test robot
Hi Ard,
kernel test robot noticed the following build errors:
[auto build test ERROR on masahiroy-kbuild/for-next]
[also build test ERROR on masahiroy-kbuild/fixes tip/x86/core s390/features linus/master v6.14-rc6 next-20250312] [If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]
url:    https://github.com/intel-lab-lkp/linux/commits/Ard-Biesheuvel/Kbuild-link-vmlinux-sh-Make-output-file-name-configurable/20250311-190926
base:   https://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild.git for-next
patch link:    https://lore.kernel.org/r/20250311110616.148682-9-ardb%2Bgit%40google.com
patch subject: [PATCH v2 3/4] Kbuild: Create intermediate vmlinux build with relocations preserved
config: x86_64-randconfig-076-20250313 (https://download.01.org/0day-ci/archive/20250313/[email protected]/config)
compiler: gcc-12 (Debian 12.2.0-14) 12.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250313/[email protected]/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <[email protected]>
| Closes: https://lore.kernel.org/oe-kbuild-all/[email protected]/

Quoted 8 lines

Quoted 6 lines
Quoted 4 lines
All errors (new ones prefixed by >>):
Quoted 1 line
Quoted 1 line
gawk: scripts/generate_builtin_ranges.awk:82: fatal: cannot open file `vmlinux.map' for reading: No such file or directory
Hmm it seems I missed some things in link-vmlinux.sh - I will take a look.
We'd need something like the below applied on top - shall I send a v3?

I will insert this before you patch set.
https://lore.kernel.org/linux-kbuild/[email protected]/T/#u

I would have done this earlier.
That is simply because I always run out of my time
and I do not have time to fix issues before someone stumbles on them.

Quoted 61 lines

scripts/link-vmlinux.sh +7 -6

@@ -46,6 +46,7 @@
 
 # Link of vmlinux
 # ${1} - output file
+# ${2} - map file
 vmlinux_link()
 {
        local output=${1}

@@ -99,7 +100,7 @@ vmlinux_link()
        fi
 
        if is_enabled CONFIG_VMLINUX_MAP; then
-               ldflags="${ldflags} ${wl}-Map=${output}.map"
+               ldflags="${ldflags} ${wl}-Map=${2}"
        fi
 
        ${ld} ${ldflags} -o ${output}                                   \

@@ -185,7 +186,7 @@
 {
        rm -f .btf.*
        rm -f System.map
-       rm -f vmlinux
+       rm -f ${VMLINUX}
        rm -f vmlinux.map
 }

@@ -224,7 +225,7 @@
                strip_debug=1
        fi
 
-       vmlinux_link .tmp_vmlinux1
+       vmlinux_link .tmp_vmlinux1 .tmp_vmlinux1.map
 fi
 
 if is_enabled CONFIG_DEBUG_INFO_BTF; then

@@ -267,19 +268,19 @@
        sysmap_and_kallsyms .tmp_vmlinux1
        size1=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso})
 
-       vmlinux_link .tmp_vmlinux2
+       vmlinux_link .tmp_vmlinux2 .tmp_vmlinux2.map
        sysmap_and_kallsyms .tmp_vmlinux2
        size2=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso})
 
        if [ $size1 -ne $size2 ] || [ -n "${KALLSYMS_EXTRA_PASS}" ]; then
-               vmlinux_link .tmp_vmlinux3
+               vmlinux_link .tmp_vmlinux3 .tmp_vmlinux3.map
                sysmap_and_kallsyms .tmp_vmlinux3
        fi
 fi
 
 strip_debug=
 
-vmlinux_link "${VMLINUX}"
+vmlinux_link "${VMLINUX}" vmlinux.map
 
 # fill in BTF IDs
 if is_enabled CONFIG_DEBUG_INFO_BTF; then

Signature · 2 lines

Best Regards
Masahiro Yamada

Heiko Carstens

maintainer

2025-03-18 08:18 UTC #8 lore raw

Re: [PATCH v2 3/4] Kbuild: Create intermediate vmlinux build with relocations preserved

Quoted 35 lines · Masahiro Yamada

Quoted 23 lines · Ard Biesheuvel
Quoted 22 lines · Ard Biesheuvel
Quoted 21 lines · kernel test robot
kernel test robot noticed the following build errors:
[auto build test ERROR on masahiroy-kbuild/for-next]
[also build test ERROR on masahiroy-kbuild/fixes tip/x86/core s390/features linus/master v6.14-rc6 next-20250312] [If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]
url:    https://github.com/intel-lab-lkp/linux/commits/Ard-Biesheuvel/Kbuild-link-vmlinux-sh-Make-output-file-name-configurable/20250311-190926
base:   https://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild.git for-next
patch link:    https://lore.kernel.org/r/20250311110616.148682-9-ardb%2Bgit%40google.com
patch subject: [PATCH v2 3/4] Kbuild: Create intermediate vmlinux build with relocations preserved
config: x86_64-randconfig-076-20250313 (https://download.01.org/0day-ci/archive/20250313/[email protected]/config)
compiler: gcc-12 (Debian 12.2.0-14) 12.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250313/[email protected]/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <[email protected]>
| Closes: https://lore.kernel.org/oe-kbuild-all/[email protected]/
Quoted 8 lines
Quoted 6 lines
Quoted 4 lines
All errors (new ones prefixed by >>):
Quoted 1 line
Quoted 1 line
gawk: scripts/generate_builtin_ranges.awk:82: fatal: cannot open file `vmlinux.map' for reading: No such file or directory
Hmm it seems I missed some things in link-vmlinux.sh - I will take a look.
We'd need something like the below applied on top - shall I send a v3?
I will insert this before you patch set.
https://lore.kernel.org/linux-kbuild/[email protected]/T/#u

...

Quoted 2 lines

Quoted 2 lines
scripts/link-vmlinux.sh +0 -0

...

Quoted 5 lines

scripts/link-vmlinux.sh
Quoted 5 lines
scripts/link-vmlinux.sh +1 -1
-vmlinux_link "${VMLINUX}"
+vmlinux_link "${VMLINUX}" vmlinux.map
 
 # fill in BTF IDs
 if is_enabled CONFIG_DEBUG_INFO_BTF; then

Building linux-next breaks on s390 with DEBUG_INFO_BTF enabled because of this; just where your addon patch ends:

LD vmlinux.unstripped
BTFIDS vmlinux
FAILED cannot open vmlinux: No such file or directory make[2]: *** [scripts/Makefile.vmlinux:91: vmlinux.unstripped] Error 255 make[2]: *** Deleting file 'vmlinux.unstripped'
make[1]: *** [/home/builder/linux-next/Makefile:1239: vmlinux] Error 2
make: *** [Makefile:248: __sub-make] Error 2

I guess _something_ like below is needed to fix this (works for me(tm)):

scripts/link-vmlinux.sh +2 -2

index 4949d0c8c267..51367c2bfc21 100755
@@ -286,12 +286,12 @@ vmlinux_link "${VMLINUX}"
 
 # fill in BTF IDs
 if is_enabled CONFIG_DEBUG_INFO_BTF; then
-	info BTFIDS vmlinux
+	info BTFIDS "${VMLINUX}"
 	RESOLVE_BTFIDS_ARGS=""
 	if is_enabled CONFIG_WERROR; then
 		RESOLVE_BTFIDS_ARGS=" --fatal_warnings "
 	fi
-	${RESOLVE_BTFIDS} ${RESOLVE_BTFIDS_ARGS} vmlinux
+	${RESOLVE_BTFIDS} ${RESOLVE_BTFIDS_ARGS} "${VMLINUX}"
 fi
 
 mksysmap "${VMLINUX}" System.map

Ard Biesheuvel

2025-03-18 08:27 UTC #9 lore raw

Re: [PATCH v2 3/4] Kbuild: Create intermediate vmlinux build with relocations preserved

Quoted 41 lines · Heiko Carstens

Quoted 35 lines · Masahiro Yamada
Quoted 23 lines · Ard Biesheuvel
Quoted 22 lines · Ard Biesheuvel
Quoted 21 lines · kernel test robot
kernel test robot noticed the following build errors:
[auto build test ERROR on masahiroy-kbuild/for-next]
[also build test ERROR on masahiroy-kbuild/fixes tip/x86/core s390/features linus/master v6.14-rc6 next-20250312] [If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]
url:    https://github.com/intel-lab-lkp/linux/commits/Ard-Biesheuvel/Kbuild-link-vmlinux-sh-Make-output-file-name-configurable/20250311-190926
base:   https://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild.git for-next
patch link:    https://lore.kernel.org/r/20250311110616.148682-9-ardb%2Bgit%40google.com
patch subject: [PATCH v2 3/4] Kbuild: Create intermediate vmlinux build with relocations preserved
config: x86_64-randconfig-076-20250313 (https://download.01.org/0day-ci/archive/20250313/[email protected]/config)
compiler: gcc-12 (Debian 12.2.0-14) 12.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250313/[email protected]/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <[email protected]>
| Closes: https://lore.kernel.org/oe-kbuild-all/[email protected]/
Quoted 8 lines
Quoted 6 lines
Quoted 4 lines
All errors (new ones prefixed by >>):
Quoted 1 line
Quoted 1 line
gawk: scripts/generate_builtin_ranges.awk:82: fatal: cannot open file `vmlinux.map' for reading: No such file or directory
Hmm it seems I missed some things in link-vmlinux.sh - I will take a look.
We'd need something like the below applied on top - shall I send a v3?
I will insert this before you patch set.
https://lore.kernel.org/linux-kbuild/[email protected]/T/#u
...
Quoted 2 lines
Quoted 2 lines
scripts/link-vmlinux.sh +0 -0
...

Quoted 9 lines

Quoted 5 lines
scripts/link-vmlinux.sh vmlinux_link "${VMLINUX}" · line 288
Quoted 5 lines
scripts/link-vmlinux.sh +1 -1
-vmlinux_link "${VMLINUX}"
+vmlinux_link "${VMLINUX}" vmlinux.map
 
 # fill in BTF IDs
 if is_enabled CONFIG_DEBUG_INFO_BTF; then
Building linux-next breaks on s390 with DEBUG_INFO_BTF enabled because of this; just where your addon patch ends:

Apologies for the breakage - this should already have been fixed in the kbuild tree [0] but the fix does not appear to have landed yet.

[0] https://lore.kernel.org/all/[email protected]

Masahiro?

Masahiro Yamada

2025-03-18 16:27 UTC #10 lore raw

Re: [PATCH v2 3/4] Kbuild: Create intermediate vmlinux build with relocations preserved

Quoted 53 lines · Ard Biesheuvel

Quoted 41 lines · Heiko Carstens
Quoted 35 lines · Masahiro Yamada
Quoted 23 lines · Ard Biesheuvel
Quoted 22 lines · Ard Biesheuvel
Quoted 21 lines · kernel test robot
kernel test robot noticed the following build errors:
[auto build test ERROR on masahiroy-kbuild/for-next]
[also build test ERROR on masahiroy-kbuild/fixes tip/x86/core s390/features linus/master v6.14-rc6 next-20250312] [If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]
url:    https://github.com/intel-lab-lkp/linux/commits/Ard-Biesheuvel/Kbuild-link-vmlinux-sh-Make-output-file-name-configurable/20250311-190926
base:   https://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild.git for-next
patch link:    https://lore.kernel.org/r/20250311110616.148682-9-ardb%2Bgit%40google.com
patch subject: [PATCH v2 3/4] Kbuild: Create intermediate vmlinux build with relocations preserved
config: x86_64-randconfig-076-20250313 (https://download.01.org/0day-ci/archive/20250313/[email protected]/config)
compiler: gcc-12 (Debian 12.2.0-14) 12.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250313/[email protected]/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <[email protected]>
| Closes: https://lore.kernel.org/oe-kbuild-all/[email protected]/
Quoted 8 lines
Quoted 6 lines
Quoted 4 lines
All errors (new ones prefixed by >>):
Quoted 1 line
Quoted 1 line
gawk: scripts/generate_builtin_ranges.awk:82: fatal: cannot open file `vmlinux.map' for reading: No such file or directory
Hmm it seems I missed some things in link-vmlinux.sh - I will take a look.
We'd need something like the below applied on top - shall I send a v3?
I will insert this before you patch set.
https://lore.kernel.org/linux-kbuild/[email protected]/T/#u
...
Quoted 2 lines
Quoted 2 lines
scripts/link-vmlinux.sh +0 -0
...
Quoted 9 lines
Quoted 5 lines
scripts/link-vmlinux.sh vmlinux_link "${VMLINUX}" · line 288
Quoted 5 lines
scripts/link-vmlinux.sh +1 -1
-vmlinux_link "${VMLINUX}"
+vmlinux_link "${VMLINUX}" vmlinux.map
 
 # fill in BTF IDs
 if is_enabled CONFIG_DEBUG_INFO_BTF; then
Building linux-next breaks on s390 with DEBUG_INFO_BTF enabled because of this; just where your addon patch ends:

Quoted 7 lines

Apologies for the breakage - this should already have been fixed in the kbuild tree [0] but the fix does not appear to have landed yet.
[0] https://lore.kernel.org/all/[email protected]
Masahiro?

Sorry, I had applied the fix-up locally, but
forgot to do "git push".

The correct one is now available, and I hope
tomorrow's linux-next will be OK.

Signature · 2 lines

Best Regards
Masahiro Yamada

Conor Dooley

2025-04-30 16:04 UTC #11 lore raw

Re: [PATCH v2 3/4] Kbuild: Create intermediate vmlinux build with relocations preserved

In reply to Ard Biesheuvel

+CC Palmer

Quoted 21 lines · Ard Biesheuvel

From: Ard Biesheuvel <[email protected]>
The imperative paradigm used to build vmlinux, extract some info from it or perform some checks on it, and subsequently modify it again goes against the declarative paradigm that is usually employed for defining make rules.
In particular, the Makefile.postlink files that consume their input via an output rule result in some dodgy logic in the decompressor makefiles for RISC-V and x86, given that the vmlinux.relocs input file needed to generate the arch-specific relocation tables may not exist or be out of date, but cannot be constructed using the ordinary Make dependency based rules, because the info needs to be extracted while vmlinux is in its ephemeral, non-stripped form.
So instead, for architectures that require the static relocations that are emitted into vmlinux when passing --emit-relocs to the linker, and are subsequently stripped out again, introduce an intermediate vmlinux target called vmlinux.unstripped, and organize the reset of the build logic accordingly:

Quoted 7 lines

- vmlinux.unstripped is created only once, and not updated again
- build rules under arch/*/boot can depend on vmlinux.unstripped without running the risk of the data disappearing or being out of date
- the final vmlinux generated by the build is not bloated with static relocations that are never needed again after the build completes.
Signed-off-by Ard Biesheuvel <[email protected]>

Delayed report since I have been slacking on my testing, but looks like this has broken boot for me on riscv (mpfs-icicle-kit), no output after "Starting kernel", defconfig should be:
https://raw.githubusercontent.com/ConchuOD/riscv-env/refs/heads/dev/conf/defconfig
Toolchain is llvm 16. LMK if there's some salient info missing.

Cheers,
Conor.

Palmer Dabbelt

maintainer

2025-04-30 16:29 UTC #12 lore raw

Re: [PATCH v2 3/4] Kbuild: Create intermediate vmlinux build with relocations preserved

Quoted 30 lines · Conor Dooley

+CC Palmer
Quoted 27 lines · Ard Biesheuvel
From: Ard Biesheuvel <[email protected]>
The imperative paradigm used to build vmlinux, extract some info from it or perform some checks on it, and subsequently modify it again goes against the declarative paradigm that is usually employed for defining make rules.
In particular, the Makefile.postlink files that consume their input via an output rule result in some dodgy logic in the decompressor makefiles for RISC-V and x86, given that the vmlinux.relocs input file needed to generate the arch-specific relocation tables may not exist or be out of date, but cannot be constructed using the ordinary Make dependency based rules, because the info needs to be extracted while vmlinux is in its ephemeral, non-stripped form.
So instead, for architectures that require the static relocations that are emitted into vmlinux when passing --emit-relocs to the linker, and are subsequently stripped out again, introduce an intermediate vmlinux target called vmlinux.unstripped, and organize the reset of the build logic accordingly:
- vmlinux.unstripped is created only once, and not updated again
- build rules under arch/*/boot can depend on vmlinux.unstripped without running the risk of the data disappearing or being out of date
- the final vmlinux generated by the build is not bloated with static relocations that are never needed again after the build completes.

Quoted 7 lines

Quoted 1 line
Signed-off-by Ard Biesheuvel <[email protected]>
Delayed report since I have been slacking on my testing, but looks like this has broken boot for me on riscv (mpfs-icicle-kit), no output after "Starting kernel", defconfig should be:
https://raw.githubusercontent.com/ConchuOD/riscv-env/refs/heads/dev/conf/defconfig
Toolchain is llvm 16. LMK if there's some salient info missing.

Thanks for tracking this down. It's not manifesting on my end, but we talked this morning about this maybe being some config-specific issue. I'm also on LLVM 18.

I'm going to start poking around with the configs...

Quoted 3 lines

Cheers,
Conor.

Ard Biesheuvel

author

2025-03-11 11:06 UTC #13 lore raw

PATCH v2 4/4 x86: Get rid of Makefile.postlink

In reply to Ard Biesheuvel

From: Ard Biesheuvel <[email protected]>

Instead of generating the vmlinux.relocs file (needed by the decompressor build to construct the KASLR relocation tables) as a vmlinux postlink step, which is dubious because it depends on data that is stripped from vmlinux before the build completes, generate it from vmlinux.unstripped, which has been introduced specifically for this purpose.

This ensures that each artifact is rebuilt as needed, rather than as a side effect of another build rule.

This effectively reverts commit

9d9173e9ceb6 ("x86/build: Avoid relocation information in final vmlinux")

Signed-off-by Ard Biesheuvel <[email protected]>

---
 arch/x86/Makefile.postlink        | 38 --------------------
 arch/x86/boot/compressed/Makefile |  9 +++--
 2 files changed, 6 insertions(+), 41 deletions(-)

arch/x86/Makefile.postlink deleted +0 ~~-38~~

deleted file mode 100644
index 445fce66630f..000000000000
@@ -1,38 +0,0 @@
-# SPDX-License-Identifier: GPL-2.0
-# ===========================================================================
-# Post-link x86 pass
-# ===========================================================================
-#
-# 1. Separate relocations from vmlinux into vmlinux.relocs.
-# 2. Strip relocations from vmlinux.
-
-PHONY := __archpost
-__archpost:
-
--include include/config/auto.conf
-include $(srctree)/scripts/Kbuild.include
-
-CMD_RELOCS = arch/x86/tools/relocs
-OUT_RELOCS = arch/x86/boot/compressed
-quiet_cmd_relocs = RELOCS  $(OUT_RELOCS)/vmlinux.relocs
-      cmd_relocs = \
-	mkdir -p $(OUT_RELOCS); \
-	$(CMD_RELOCS) $@ > $(OUT_RELOCS)/vmlinux.relocs; \
-	$(CMD_RELOCS) --abs-relocs $@
-
-# `@true` prevents complaint when there is nothing to be done
-
-vmlinux vmlinux.unstripped: FORCE
-	@true
-ifeq ($(CONFIG_X86_NEED_RELOCS),y)
-	$(call cmd,relocs)
-endif
-
-clean:
-	@rm -f $(OUT_RELOCS)/vmlinux.relocs
-
-PHONY += FORCE clean
-
-FORCE:
-
-.PHONY: $(PHONY)

arch/x86/boot/compressed/Makefile +6 -3

index 606c74f27459..5edee7a9786c 100644
@@ -117,9 +117,12 @@ $(obj)/vmlinux.bin: vmlinux FORCE
 
 targets += $(patsubst $(obj)/%,%,$(vmlinux-objs-y)) vmlinux.bin.all vmlinux.relocs
 
-# vmlinux.relocs is created by the vmlinux postlink step.
-$(obj)/vmlinux.relocs: vmlinux
-	@true
+CMD_RELOCS = arch/x86/tools/relocs
+quiet_cmd_relocs = RELOCS  $@
+      cmd_relocs = $(CMD_RELOCS) $< > $@;$(CMD_RELOCS) --abs-relocs $<
+
+$(obj)/vmlinux.relocs: vmlinux.unstripped FORCE
+	$(call if_changed,relocs)
 
 vmlinux.bin.all-y := $(obj)/vmlinux.bin
 vmlinux.bin.all-$(CONFIG_X86_NEED_RELOCS) += $(obj)/vmlinux.relocs

Signature · 1 line

2.49.0.rc0.332.g42c0ae87b1-goog

Borislav Petkov

maintainer

2025-03-11 11:18 UTC #14 lore raw

Re: [PATCH v2 4/4] x86: Get rid of Makefile.postlink

+ Petr for 9d9173e9ceb6

@Petr, you can find the whole thread on lore.

Quoted 89 lines · Ard Biesheuvel

From: Ard Biesheuvel <[email protected]>

This ensures that each artifact is rebuilt as needed, rather than as a side effect of another build rule.

This effectively reverts commit

9d9173e9ceb6 ("x86/build: Avoid relocation information in final vmlinux")

Signed-off-by Ard Biesheuvel <[email protected]>

---
 arch/x86/Makefile.postlink        | 38 --------------------
 arch/x86/boot/compressed/Makefile |  9 +++--
 2 files changed, 6 insertions(+), 41 deletions(-)

arch/x86/Makefile.postlink deleted +0 ~~-38~~

deleted file mode 100644
index 445fce66630f..000000000000
@@ -1,38 +0,0 @@
-# SPDX-License-Identifier: GPL-2.0
-# ===========================================================================
-# Post-link x86 pass
-# ===========================================================================
-#
-# 1. Separate relocations from vmlinux into vmlinux.relocs.
-# 2. Strip relocations from vmlinux.
-
-PHONY := __archpost
-__archpost:
-
--include include/config/auto.conf
-include $(srctree)/scripts/Kbuild.include
-
-CMD_RELOCS = arch/x86/tools/relocs
-OUT_RELOCS = arch/x86/boot/compressed
-quiet_cmd_relocs = RELOCS  $(OUT_RELOCS)/vmlinux.relocs
-      cmd_relocs = \
-	mkdir -p $(OUT_RELOCS); \
-	$(CMD_RELOCS) $@ > $(OUT_RELOCS)/vmlinux.relocs; \
-	$(CMD_RELOCS) --abs-relocs $@
-
-# `@true` prevents complaint when there is nothing to be done
-
-vmlinux vmlinux.unstripped: FORCE
-	@true
-ifeq ($(CONFIG_X86_NEED_RELOCS),y)
-	$(call cmd,relocs)
-endif
-
-clean:
-	@rm -f $(OUT_RELOCS)/vmlinux.relocs
-
-PHONY += FORCE clean
-
-FORCE:
-
-.PHONY: $(PHONY)

arch/x86/boot/compressed/Makefile +6 -3

index 606c74f27459..5edee7a9786c 100644
@@ -117,9 +117,12 @@ $(obj)/vmlinux.bin: vmlinux FORCE
 
 targets += $(patsubst $(obj)/%,%,$(vmlinux-objs-y)) vmlinux.bin.all vmlinux.relocs
 
-# vmlinux.relocs is created by the vmlinux postlink step.
-$(obj)/vmlinux.relocs: vmlinux
-	@true
+CMD_RELOCS = arch/x86/tools/relocs
+quiet_cmd_relocs = RELOCS  $@
+      cmd_relocs = $(CMD_RELOCS) $< > $@;$(CMD_RELOCS) --abs-relocs $<
+
+$(obj)/vmlinux.relocs: vmlinux.unstripped FORCE
+	$(call if_changed,relocs)
 
 vmlinux.bin.all-y := $(obj)/vmlinux.bin
 vmlinux.bin.all-$(CONFIG_X86_NEED_RELOCS) += $(obj)/vmlinux.relocs

Signature · 1 line

2.49.0.rc0.332.g42c0ae87b1-goog

Signature · 4 lines

Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette

Petr Pavlu

2025-03-12 12:36 UTC #15 lore raw

Re: [PATCH v2 4/4] x86: Get rid of Makefile.postlink

Quoted 22 lines · Borislav Petkov

+ Petr for 9d9173e9ceb6
@Petr, you can find the whole thread on lore.
Quoted 17 lines · Ard Biesheuvel
From: Ard Biesheuvel <[email protected]>
Instead of generating the vmlinux.relocs file (needed by the decompressor build to construct the KASLR relocation tables) as a vmlinux postlink step, which is dubious because it depends on data that is stripped from vmlinux before the build completes, generate it from vmlinux.unstripped, which has been introduced specifically for this purpose.
This ensures that each artifact is rebuilt as needed, rather than as a side effect of another build rule.
This effectively reverts commit
9d9173e9ceb6 ("x86/build: Avoid relocation information in final vmlinux")
Signed-off-by Ard Biesheuvel <[email protected]>

For what it's worth, the changes look to me as an improvement over the previous implementation.

Signature · 2 lines

Thanks,
Petr

Masahiro Yamada

2025-03-13 02:09 UTC #16 lore raw

Re: [PATCH v2 4/4] x86: Get rid of Makefile.postlink

In reply to Ard Biesheuvel

Quoted 74 lines · Ard Biesheuvel

From: Ard Biesheuvel <[email protected]>
Instead of generating the vmlinux.relocs file (needed by the decompressor build to construct the KASLR relocation tables) as a vmlinux postlink step, which is dubious because it depends on data that is stripped from vmlinux before the build completes, generate it from vmlinux.unstripped, which has been introduced specifically for this purpose.
This ensures that each artifact is rebuilt as needed, rather than as a side effect of another build rule.
This effectively reverts commit
9d9173e9ceb6 ("x86/build: Avoid relocation information in final vmlinux")
Signed-off-by Ard Biesheuvel <[email protected]>
---
 arch/x86/Makefile.postlink        | 38 --------------------
 arch/x86/boot/compressed/Makefile |  9 +++--
 2 files changed, 6 insertions(+), 41 deletions(-)
arch/x86/Makefile.postlink deleted +0 ~~-38~~
deleted file mode 100644
index 445fce66630f..000000000000
@@ -1,38 +0,0 @@
-# SPDX-License-Identifier: GPL-2.0
-# ===========================================================================
-# Post-link x86 pass
-# ===========================================================================
-#
-# 1. Separate relocations from vmlinux into vmlinux.relocs.
-# 2. Strip relocations from vmlinux.
-
-PHONY := __archpost
-__archpost:
-
--include include/config/auto.conf
-include $(srctree)/scripts/Kbuild.include
-
-CMD_RELOCS = arch/x86/tools/relocs
-OUT_RELOCS = arch/x86/boot/compressed
-quiet_cmd_relocs = RELOCS  $(OUT_RELOCS)/vmlinux.relocs
-      cmd_relocs = \
-       mkdir -p $(OUT_RELOCS); \
-       $(CMD_RELOCS) $@ > $(OUT_RELOCS)/vmlinux.relocs; \
-       $(CMD_RELOCS) --abs-relocs $@
-
-# `@true` prevents complaint when there is nothing to be done
-
-vmlinux vmlinux.unstripped: FORCE
-       @true
-ifeq ($(CONFIG_X86_NEED_RELOCS),y)
-       $(call cmd,relocs)
-endif
-
-clean:
-       @rm -f $(OUT_RELOCS)/vmlinux.relocs
-
-PHONY += FORCE clean
-
-FORCE:
-
-.PHONY: $(PHONY)
arch/x86/boot/compressed/Makefile +0 -0
index 606c74f27459..5edee7a9786c 100644
@@ -117,9 +117,12 @@ $(obj)/vmlinux.bin: vmlinux FORCE
 
 targets += $(patsubst $(obj)/%,%,$(vmlinux-objs-y)) vmlinux.bin.all vmlinux.relocs

arch/x86/boot/compressed/Makefile $(obj)/vmlinux.bin: vmlinux FORCE · line 125

Quoted 10 lines

arch/x86/boot/compressed/Makefile +6 -3

 
-# vmlinux.relocs is created by the vmlinux postlink step.
-$(obj)/vmlinux.relocs: vmlinux
-       @true
+CMD_RELOCS = arch/x86/tools/relocs
+quiet_cmd_relocs = RELOCS  $@
+      cmd_relocs = $(CMD_RELOCS) $< > $@;$(CMD_RELOCS) --abs-relocs $<
+
+$(obj)/vmlinux.relocs: vmlinux.unstripped FORCE
+       $(call if_changed,relocs)

Perhaps, it may make sense to rebuild vmlinux.relocs when arch/x86/tools/relocs is changed, but
I do not see such dependency in the other arch/x86/realmode/rm/Makefile.

https://github.com/torvalds/linux/blob/v6.14-rc5/arch/x86/realmode/rm/Makefile#L61

So, I decided it is ok.
If you mind, you can send v3.

Signature · 2 lines

Best Regards
Masahiro Yamada

Ard Biesheuvel

2025-03-13 07:47 UTC #17 lore raw

Re: [PATCH v2 4/4] x86: Get rid of Makefile.postlink

Quoted 92 lines · Masahiro Yamada

Quoted 74 lines · Ard Biesheuvel
From: Ard Biesheuvel <[email protected]>
Instead of generating the vmlinux.relocs file (needed by the decompressor build to construct the KASLR relocation tables) as a vmlinux postlink step, which is dubious because it depends on data that is stripped from vmlinux before the build completes, generate it from vmlinux.unstripped, which has been introduced specifically for this purpose.
This ensures that each artifact is rebuilt as needed, rather than as a side effect of another build rule.
This effectively reverts commit
9d9173e9ceb6 ("x86/build: Avoid relocation information in final vmlinux")
Signed-off-by Ard Biesheuvel <[email protected]>
---
 arch/x86/Makefile.postlink        | 38 --------------------
 arch/x86/boot/compressed/Makefile |  9 +++--
 2 files changed, 6 insertions(+), 41 deletions(-)
arch/x86/Makefile.postlink deleted +0 ~~-38~~
deleted file mode 100644
index 445fce66630f..000000000000
@@ -1,38 +0,0 @@
-# SPDX-License-Identifier: GPL-2.0
-# ===========================================================================
-# Post-link x86 pass
-# ===========================================================================
-#
-# 1. Separate relocations from vmlinux into vmlinux.relocs.
-# 2. Strip relocations from vmlinux.
-
-PHONY := __archpost
-__archpost:
-
--include include/config/auto.conf
-include $(srctree)/scripts/Kbuild.include
-
-CMD_RELOCS = arch/x86/tools/relocs
-OUT_RELOCS = arch/x86/boot/compressed
-quiet_cmd_relocs = RELOCS  $(OUT_RELOCS)/vmlinux.relocs
-      cmd_relocs = \
-       mkdir -p $(OUT_RELOCS); \
-       $(CMD_RELOCS) $@ > $(OUT_RELOCS)/vmlinux.relocs; \
-       $(CMD_RELOCS) --abs-relocs $@
-
-# `@true` prevents complaint when there is nothing to be done
-
-vmlinux vmlinux.unstripped: FORCE
-       @true
-ifeq ($(CONFIG_X86_NEED_RELOCS),y)
-       $(call cmd,relocs)
-endif
-
-clean:
-       @rm -f $(OUT_RELOCS)/vmlinux.relocs
-
-PHONY += FORCE clean
-
-FORCE:
-
-.PHONY: $(PHONY)
arch/x86/boot/compressed/Makefile +0 -0
index 606c74f27459..5edee7a9786c 100644
@@ -117,9 +117,12 @@ $(obj)/vmlinux.bin: vmlinux FORCE
 
 targets += $(patsubst $(obj)/%,%,$(vmlinux-objs-y)) vmlinux.bin.all vmlinux.relocs
arch/x86/boot/compressed/Makefile $(obj)/vmlinux.bin: vmlinux FORCE · line 125
Quoted 10 lines
arch/x86/boot/compressed/Makefile +6 -3
 
-# vmlinux.relocs is created by the vmlinux postlink step.
-$(obj)/vmlinux.relocs: vmlinux
-       @true
+CMD_RELOCS = arch/x86/tools/relocs
+quiet_cmd_relocs = RELOCS  $@
+      cmd_relocs = $(CMD_RELOCS) $< > $@;$(CMD_RELOCS) --abs-relocs $<
+
+$(obj)/vmlinux.relocs: vmlinux.unstripped FORCE
+       $(call if_changed,relocs)
Perhaps, it may make sense to rebuild vmlinux.relocs when arch/x86/tools/relocs is changed, but
I do not see such dependency in the other arch/x86/realmode/rm/Makefile.

Quoted 6 lines

https://github.com/torvalds/linux/blob/v6.14-rc5/arch/x86/realmode/rm/Makefile#L61
So, I decided it is ok.
If you mind, you can send v3.

No I think that's fine: this patch reverts the changes to arch/x86/boot/compressed/Makefile; if we need to improve it, it should be a separate change in any case.

Masahiro Yamada

2025-03-15 07:10 UTC #18 lore raw

In reply to Ard Biesheuvel

Quoted 28 lines · Ard Biesheuvel

From: Ard Biesheuvel <[email protected]>
Kbuild supports an architecture specific Makefile.postlink file that is invoked for the vmlinux target after it has been built. This Makefile takes 'vmlinux' (which has just been built) as the target, and mangles the file and/or constructs other intermediate artifacts from it.
This violates the general philosophy of Make, which is based on rules and dependencies, and artifacts that are rebuilt only when any of their dependencies have been updated.
Instead, the different incarnations of vmlinux that are consumed by different stages of the build should be emitted as distinct files, where rules and dependencies are used to define one in terms of the other.
This also works around an error observed here [0], where vmlinux is deleted by Make because a subsequent step that consumes it as input throws an error.
So refactor the vmlinux shell scripts and build rules so that architectures that rely on --emit-relocs to construct vmlinux with static relocations preserved will get a separate vmlinux.unstripped file carrying those relocations. This removes the need for an imperative postlink step, given that any rules that depend on the unstripped vmlinux can now simply depend on vmlinux.unstripped, rather than inject a build step into Makefile.postlink

Quoted 8 lines

S390 should be able to do the same. MIPS and RISC-V perform some post-build checks on vmlinux, which is reasonable in principle for a postlink step, although deleting vmlinux when the check fails is equally unhelpful.
Changes since v1:
- add vmlinux.unstripped to .gitignore and to the 'clean' target
- move cmd_strip_relocs into Makefile.vmlinux

Applied to linux-kbuild.
Thanks!

Signature · 2 lines

Best Regards
Masahiro Yamada