Merge tag 'kbuild-v6.15' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

Pull Kbuild updates from Masahiro Yamada:

 - Improve performance in gendwarfksyms

 - Remove deprecated EXTRA_*FLAGS and KBUILD_ENABLE_EXTRA_GCC_CHECKS

 - Support CONFIG_HEADERS_INSTALL for ARCH=um

 - Use more relative paths to sources files for better reproducibility

 - Support the loong64 Debian architecture

 - Add Kbuild bash completion

 - Introduce intermediate vmlinux.unstripped for architectures that need
   static relocations to be stripped from the final vmlinux

 - Fix versioning in Debian packages for -rc releases

 - Treat missing MODULE_DESCRIPTION() as an error

 - Convert Nios2 Makefiles to use the generic rule for built-in DTB

 - Add debuginfo support to the RPM package

* tag 'kbuild-v6.15' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (40 commits)
  kbuild: rpm-pkg: build a debuginfo RPM
  kconfig: merge_config: use an empty file as initfile
  nios2: migrate to the generic rule for built-in DTB
  rust: kbuild: skip `--remap-path-prefix` for `rustdoc`
  kbuild: pacman-pkg: hardcode module installation path
  kbuild: deb-pkg: don't set KBUILD_BUILD_VERSION unconditionally
  modpost: require a MODULE_DESCRIPTION()
  kbuild: make all file references relative to source root
  x86: drop unnecessary prefix map configuration
  kbuild: deb-pkg: add comment about future removal of KDEB_COMPRESS
  kbuild: Add a help message for "headers"
  kbuild: deb-pkg: remove "version" variable in mkdebian
  kbuild: deb-pkg: fix versioning for -rc releases
  Documentation/kbuild: Fix indentation in modules.rst example
  x86: Get rid of Makefile.postlink
  kbuild: Create intermediate vmlinux build with relocations preserved
  kbuild: Introduce Kconfig symbol for linking vmlinux with relocations
  kbuild: link-vmlinux.sh: Make output file name configurable
  kbuild: do not generate .tmp_vmlinux*.map when CONFIG_VMLINUX_MAP=y
  Revert "kheaders: Ignore silly-rename files"
  ...

Author: torvalds

.gitignore

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

Documentation/dev-tools/checkpatch.rst

@@ -342,24 +342,6 @@ API usage
 
     See: https://www.kernel.org/doc/html/latest/RCU/whatisRCU.html#full-list-of-rcu-apis
 
-  **DEPRECATED_VARIABLE**
-    EXTRA_{A,C,CPP,LD}FLAGS are deprecated and should be replaced by the new
-    flags added via commit f77bf01425b1 ("kbuild: introduce ccflags-y,
-    asflags-y and ldflags-y").
-
-    The following conversion scheme maybe used::
-
-      EXTRA_AFLAGS    ->  asflags-y
-      EXTRA_CFLAGS    ->  ccflags-y
-      EXTRA_CPPFLAGS  ->  cppflags-y
-      EXTRA_LDFLAGS   ->  ldflags-y
-
-    See:
-
-      1. https://lore.kernel.org/lkml/[email protected]/
-      2. https://lore.kernel.org/lkml/[email protected]/
-      3. https://www.kernel.org/doc/html/latest/kbuild/makefiles.html#compilation-flags
-
   **DEVICE_ATTR_FUNCTIONS**
     The function names used in DEVICE_ATTR is unusual.
     Typically, the store and show functions are used with <attr>_store and

Documentation/kbuild/bash-completion.rst

@@ -0,0 +1,65 @@
+.. SPDX-License-Identifier: GPL-2.0-only
+
+==========================
+Bash completion for Kbuild
+==========================
+
+The kernel build system is written using Makefiles, and Bash completion
+for the `make` command is available through the `bash-completion`_ project.
+
+However, the Makefiles for the kernel build are complex. The generic completion
+rules for the `make` command do not provide meaningful suggestions for the
+kernel build system, except for the options of the `make` command itself.
+
+To enhance completion for various variables and targets, the kernel source
+includes its own completion script at `scripts/bash-completion/make`.
+
+This script provides additional completions when working within the kernel tree.
+Outside the kernel tree, it defaults to the generic completion rules for the
+`make` command.
+
+Prerequisites
+=============
+
+The script relies on helper functions provided by `bash-completion`_ project.
+Please ensure it is installed on your system. On most distributions, you can
+install the `bash-completion` package through the standard package manager.
+
+How to use
+==========
+
+You can source the script directly::
+
+  $ source scripts/bash-completion/make
+
+Or, you can copy it into the search path for Bash completion scripts.
+For example::
+
+  $ mkdir -p ~/.local/share/bash-completion/completions
+  $ cp scripts/bash-completion/make ~/.local/share/bash-completion/completions/
+
+Details
+=======
+
+The additional completion for Kbuild is enabled in the following cases:
+
+ - You are in the root directory of the kernel source.
+ - You are in the top-level build directory created by the O= option
+   (checked via the `source` symlink pointing to the kernel source).
+ - The -C make option specifies the kernel source or build directory.
+ - The -f make option specifies a file in the kernel source or build directory.
+
+If none of the above are met, it falls back to the generic completion rules.
+
+The completion supports:
+
+  - Commonly used targets, such as `all`, `menuconfig`, `dtbs`, etc.
+  - Make (or environment) variables, such as `ARCH`, `LLVM`, etc.
+  - Single-target builds (`foo/bar/baz.o`)
+  - Configuration files (`*_defconfig` and `*.config`)
+
+Some variables offer intelligent behavior. For instance, `CROSS_COMPILE=`
+followed by a TAB displays installed toolchains. The list of defconfig files
+shown depends on the value of the `ARCH=` variable.
+
+.. _bash-completion: https://github.com/scop/bash-completion/

Documentation/kbuild/index.rst

@@ -23,6 +23,8 @@ Kernel Build System
     llvm
     gendwarfksyms
 
+    bash-completion
+
 .. only::  subproject and html
 
    Indices

Documentation/kbuild/kconfig-language.rst

@@ -194,16 +194,6 @@ applicable everywhere (see syntax).
   ability to hook into a secondary subsystem while allowing the user to
   configure that subsystem out without also having to unset these drivers.
 
-  Note: If the combination of FOO=y and BAZ=m causes a link error,
-  you can guard the function call with IS_REACHABLE()::
-
-	foo_init()
-	{
-		if (IS_REACHABLE(CONFIG_BAZ))
-			baz_register(&foo);
-		...
-	}
-
   Note: If the feature provided by BAZ is highly desirable for FOO,
   FOO should imply not only BAZ, but also its dependency BAR::
 
@@ -588,7 +578,9 @@ uses the slightly counterintuitive::
 	depends on BAR || !BAR
 
 This means that there is either a dependency on BAR that disallows
-the combination of FOO=y with BAR=m, or BAR is completely disabled.
+the combination of FOO=y with BAR=m, or BAR is completely disabled. The BAR
+module must provide all the stubs for !BAR case.
+
 For a more formalized approach if there are multiple drivers that have
 the same dependency, a helper symbol can be used, like::
 
@@ -599,6 +591,21 @@ the same dependency, a helper symbol can be used, like::
   config BAR_OPTIONAL
 	def_tristate BAR || !BAR
 
+Much less favorable way to express optional dependency is IS_REACHABLE() within
+the module code, useful for example when the module BAR does not provide
+!BAR stubs::
+
+	foo_init()
+	{
+		if (IS_REACHABLE(CONFIG_BAR))
+			bar_register(&foo);
+		...
+	}
+
+IS_REACHABLE() is generally discouraged, because the code will be silently
+discarded, when CONFIG_BAR=m and this code is built-in. This is not what users
+usually expect when enabling BAR as module.
+
 Kconfig recursive dependency limitations
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 

Documentation/kbuild/makefiles.rst

@@ -318,9 +318,6 @@ ccflags-y, asflags-y and ldflags-y
   These three flags apply only to the kbuild makefile in which they
   are assigned. They are used for all the normal cc, as and ld
   invocations happening during a recursive build.
-  Note: Flags with the same behaviour were previously named:
-  EXTRA_CFLAGS, EXTRA_AFLAGS and EXTRA_LDFLAGS.
-  They are still supported but their usage is deprecated.
 
   ccflags-y specifies options for compiling with $(CC).
 
@@ -670,6 +667,20 @@ cc-cross-prefix
             endif
     endif
 
+$(RUSTC) support functions
+--------------------------
+
+rustc-min-version
+  rustc-min-version tests if the value of $(CONFIG_RUSTC_VERSION) is greater
+  than or equal to the provided value and evaluates to y if so.
+
+  Example::
+
+    rustflags-$(call rustc-min-version, 108500) := -Cfoo
+
+  In this example, rustflags-y will be assigned the value -Cfoo if
+  $(CONFIG_RUSTC_VERSION) is >= 1.85.0.
+
 $(LD) support functions
 -----------------------
 

Documentation/kbuild/modules.rst

@@ -318,7 +318,7 @@ Several Subdirectories
 		|	|__ include
 		|	    |__ hardwareif.h
 		|__ include
-		|__ complex.h
+			|__ complex.h
 
 	To build the module complex.ko, we then need the following
 	kbuild file::

Documentation/kbuild/reproducible-builds.rst

@@ -46,21 +46,6 @@ The kernel embeds the building user and host names in
 `KBUILD_BUILD_USER and KBUILD_BUILD_HOST`_ variables.  If you are
 building from a git commit, you could use its committer address.
 
-Absolute filenames
-------------------
-
-When the kernel is built out-of-tree, debug information may include
-absolute filenames for the source files.  This must be overridden by
-including the ``-fdebug-prefix-map`` option in the `KCFLAGS`_ variable.
-
-Depending on the compiler used, the ``__FILE__`` macro may also expand
-to an absolute filename in an out-of-tree build.  Kbuild automatically
-uses the ``-fmacro-prefix-map`` option to prevent this, if it is
-supported.
-
-The Reproducible Builds web site has more information about these
-`prefix-map options`_.
-
 Generated files in source packages
 ----------------------------------
 
@@ -131,7 +116,5 @@ See ``scripts/setlocalversion`` for details.
 
 .. _KBUILD_BUILD_TIMESTAMP: kbuild.html#kbuild-build-timestamp
 .. _KBUILD_BUILD_USER and KBUILD_BUILD_HOST: kbuild.html#kbuild-build-user-kbuild-build-host
-.. _KCFLAGS: kbuild.html#kcflags
-.. _prefix-map options: https://reproducible-builds.org/docs/build-path/
 .. _Reproducible Builds project: https://reproducible-builds.org/
 .. _SOURCE_DATE_EPOCH: https://reproducible-builds.org/docs/source-date-epoch/

MAINTAINERS

@@ -12850,6 +12850,7 @@ F:	Makefile
 F:	scripts/*vmlinux*
 F:	scripts/Kbuild*
 F:	scripts/Makefile*
+F:	scripts/bash-completion/
 F:	scripts/basic/
 F:	scripts/clang-tools/
 F:	scripts/dummy-tools/

Makefile

@@ -151,9 +151,6 @@ endif
 
 export KBUILD_EXTMOD
 
-# backward compatibility
-KBUILD_EXTRA_WARN ?= $(KBUILD_ENABLE_EXTRA_GCC_CHECKS)
-
 ifeq ("$(origin W)", "command line")
   KBUILD_EXTRA_WARN := $(W)
 endif
@@ -928,6 +925,9 @@ KBUILD_CFLAGS	+= $(CC_AUTO_VAR_INIT_ZERO_ENABLER)
 endif
 endif
 
+# Explicitly clear padding bits during variable initialization
+KBUILD_CFLAGS += $(call cc-option,-fzero-init-padding-bits=all)
+
 # While VLAs have been removed, GCC produces unreachable stack probes
 # for the randomize_kstack_offset feature. Disable it for all compilers.
 KBUILD_CFLAGS	+= $(call cc-option, -fno-stack-clash-protection)
@@ -1070,7 +1070,8 @@ endif
 
 # change __FILE__ to the relative path to the source directory
 ifdef building_out_of_srctree
-KBUILD_CPPFLAGS += $(call cc-option,-fmacro-prefix-map=$(srcroot)/=)
+KBUILD_CPPFLAGS += $(call cc-option,-ffile-prefix-map=$(srcroot)/=)
+KBUILD_RUSTFLAGS += --remap-path-prefix=$(srcroot)/=
 endif
 
 # include additional Makefiles when needed
@@ -1122,6 +1123,10 @@ 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))
@@ -1364,9 +1369,12 @@ hdr-inst := -f $(srctree)/scripts/Makefile.headersinst obj
 
 PHONY += headers
 headers: $(version_h) scripts_unifdef uapi-asm-generic archheaders archscripts
-	$(if $(filter um, $(SRCARCH)), $(error Headers not exportable for UML))
+ifdef HEADER_ARCH
+	$(Q)$(MAKE) -f $(srctree)/Makefile HEADER_ARCH= SRCARCH=$(HEADER_ARCH) headers
+else
 	$(Q)$(MAKE) $(hdr-inst)=include/uapi
 	$(Q)$(MAKE) $(hdr-inst)=arch/$(SRCARCH)/include/uapi
+endif
 
 ifdef CONFIG_HEADERS_INSTALL
 prepare: headers
@@ -1564,7 +1572,7 @@ 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
@@ -1667,7 +1675,8 @@ help:
 	@echo  '  kernelrelease	  - Output the release version string (use with make -s)'
 	@echo  '  kernelversion	  - Output the version stored in Makefile (use with make -s)'
 	@echo  '  image_name	  - Output the image name (use with make -s)'
-	@echo  '  headers_install - Install sanitised kernel headers to INSTALL_HDR_PATH'; \
+	@echo  '  headers	  - Build ready-to-install UAPI headers in usr/include'
+	@echo  '  headers_install - Install sanitised kernel UAPI headers to INSTALL_HDR_PATH'; \
 	 echo  '                    (default: $(INSTALL_HDR_PATH))'; \
 	 echo  ''
 	@echo  'Static analysers:'

arch/Kconfig

@@ -1699,6 +1699,13 @@ 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/arm64/Makefile

@@ -48,7 +48,7 @@ KBUILD_CFLAGS	+= $(CC_FLAGS_NO_FPU) \
 KBUILD_CFLAGS	+= $(call cc-disable-warning, psabi)
 KBUILD_AFLAGS	+= $(compat_vdso)
 
-ifeq ($(call test-ge, $(CONFIG_RUSTC_VERSION), 108500),y)
+ifeq ($(call rustc-min-version, 108500),y)
 KBUILD_RUSTFLAGS += --target=aarch64-unknown-none-softfloat
 else
 KBUILD_RUSTFLAGS += --target=aarch64-unknown-none -Ctarget-feature="-neon"

arch/mips/Kconfig

@@ -2618,6 +2618,7 @@ 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

@@ -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/mips/Makefile.postlink

@@ -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/nios2/Kbuild

@@ -1,6 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0-only
 
-obj-y += kernel/ mm/ platform/ boot/dts/
+obj-y += kernel/ mm/ platform/
 
 # for cleaning
 subdir- += boot

arch/nios2/boot/dts/Makefile

@@ -1,5 +1,5 @@
 # SPDX-License-Identifier: GPL-2.0
 
-obj-y := $(patsubst %.dts,%.dtb.o,$(CONFIG_NIOS2_DTB_SOURCE))
+dtb-y := $(addsuffix .dtb, $(CONFIG_BUILTIN_DTB_NAME))
 
-dtb-$(CONFIG_OF_ALL_DTBS) := $(patsubst $(src)/%.dts,%.dtb, $(wildcard $(src)/*.dts))
+dtb-$(CONFIG_OF_ALL_DTBS) += $(patsubst $(src)/%.dts,%.dtb, $(wildcard $(src)/*.dts))

arch/nios2/kernel/prom.c

@@ -32,7 +32,7 @@ void __init early_init_devtree(void *params)
 	}
 #endif
 
-#ifdef CONFIG_NIOS2_DTB_SOURCE_BOOL
+#ifdef CONFIG_BUILTIN_DTB
 	if (be32_to_cpu((__be32) *dtb) == OF_DT_HEADER)
 		params = (void *)__dtb_start;
 #endif