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

Pull Kbuild fixes from Masahiro Yamada:

 - Add proper pahole version dependency to CONFIG_GENDWARFKSYMS to avoid
   module loading errors

 - Fix UAPI header tests for the OpenRISC architecture

 - Add dependency on the libdw package in Debian and RPM packages

 - Disable -Wdefault-const-init-unsafe warnings on Clang

 - Make "make clean ARCH=um" also clean the arch/x86/ directory

 - Revert the use of -fmacro-prefix-map=, which causes issues with
   debugger usability

* tag 'kbuild-fixes-v6.15' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild:
  kbuild: fix typos "module.builtin" to "modules.builtin"
  Revert "kbuild, rust: use -fremap-path-prefix to make paths relative"
  Revert "kbuild: make all file references relative to source root"
  kbuild: fix dependency on sorttable
  init: remove unused CONFIG_CC_CAN_LINK_STATIC
  um: let 'make clean' properly clean underlying SUBARCH as well
  kbuild: Disable -Wdefault-const-init-unsafe
  kbuild: rpm-pkg: Add (elfutils-devel or libdw-devel) to BuildRequires
  kbuild: deb-pkg: Add libdw-dev:native to Build-Depends-Arch
  usr/include: openrisc: don't HDRTEST bpf_perf_event.h
  kbuild: Require pahole <v1.28 or >v1.29 with GENDWARFKSYMS on X86

Author: torvalds

Documentation/kbuild/reproducible-builds.rst

@@ -46,6 +46,21 @@ 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
 ----------------------------------
 
@@ -116,5 +131,7 @@ 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/

Makefile

@@ -1068,8 +1068,7 @@ KBUILD_CFLAGS += -fno-builtin-wcslen
 
 # change __FILE__ to the relative path to the source directory
 ifdef building_out_of_srctree
-KBUILD_CPPFLAGS += $(call cc-option,-ffile-prefix-map=$(srcroot)/=)
-KBUILD_RUSTFLAGS += --remap-path-prefix=$(srcroot)/=
+KBUILD_CPPFLAGS += $(call cc-option,-fmacro-prefix-map=$(srcroot)/=)
 endif
 
 # include additional Makefiles when needed

arch/um/Makefile

@@ -154,5 +154,6 @@ MRPROPER_FILES += $(HOST_DIR)/include/generated
 archclean:
 	@find . \( -name '*.bb' -o -name '*.bbg' -o -name '*.da' \
 		-o -name '*.gcov' \) -type f -print | xargs rm -f
+	$(Q)$(MAKE) -f $(srctree)/Makefile ARCH=$(HEADER_ARCH) clean
 
 export HEADER_ARCH SUBARCH USER_CFLAGS CFLAGS_NO_HARDENING DEV_NULL_PATH

init/Kconfig

@@ -87,11 +87,6 @@ config CC_CAN_LINK
 	default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m64-flag)) if 64BIT
 	default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m32-flag))
 
-config CC_CAN_LINK_STATIC
-	bool
-	default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m64-flag) -static) if 64BIT
-	default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m32-flag) -static)
-
 # Fixed in GCC 14, 13.3, 12.4 and 11.5
 # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113921
 config GCC_ASM_GOTO_OUTPUT_BROKEN

kernel/module/Kconfig

@@ -192,6 +192,11 @@ config GENDWARFKSYMS
 	depends on !DEBUG_INFO_REDUCED && !DEBUG_INFO_SPLIT
 	# Requires ELF object files.
 	depends on !LTO
+	# To avoid conflicts with the discarded __gendwarfksyms_ptr symbols on
+	# X86, requires pahole before commit 47dcb534e253 ("btf_encoder: Stop
+	# indexing symbols for VARs") or after commit 9810758003ce ("btf_encoder:
+	# Verify 0 address DWARF variables are in ELF section").
+	depends on !X86 || !DEBUG_INFO_BTF || PAHOLE_VERSION < 128 || PAHOLE_VERSION > 129
 	help
 	  Calculate symbol versions from DWARF debugging information using
 	  gendwarfksyms. Requires DEBUG_INFO to be enabled.

scripts/Makefile.extrawarn

@@ -37,6 +37,18 @@ KBUILD_CFLAGS += -Wno-gnu
 # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111219
 KBUILD_CFLAGS += $(call cc-disable-warning, format-overflow-non-kprintf)
 KBUILD_CFLAGS += $(call cc-disable-warning, format-truncation-non-kprintf)
+
+# Clang may emit a warning when a const variable, such as the dummy variables
+# in typecheck(), or const member of an aggregate type are not initialized,
+# which can result in unexpected behavior. However, in many audited cases of
+# the "field" variant of the warning, this is intentional because the field is
+# never used within a particular call path, the field is within a union with
+# other non-const members, or the containing object is not const so the field
+# can be modified via memcpy() / memset(). While the variable warning also gets
+# disabled with this same switch, there should not be too much coverage lost
+# because -Wuninitialized will still flag when an uninitialized const variable
+# is used.
+KBUILD_CFLAGS += $(call cc-disable-warning, default-const-init-unsafe)
 else
 
 # gcc inanely warns about local variables called 'main'

scripts/Makefile.vmlinux

@@ -94,10 +94,10 @@ $(vmlinux-final): $(RESOLVE_BTFIDS)
 endif
 
 ifdef CONFIG_BUILDTIME_TABLE_SORT
-vmlinux: scripts/sorttable
+$(vmlinux-final): scripts/sorttable
 endif
 
-# module.builtin.ranges
+# modules.builtin.ranges
 # ---------------------------------------------------------------------------
 ifdef CONFIG_BUILTIN_MODULE_RANGES
 __default: modules.builtin.ranges

scripts/Makefile.vmlinux_o

@@ -73,7 +73,7 @@ vmlinux.o: $(initcalls-lds) vmlinux.a $(KBUILD_VMLINUX_LIBS) FORCE
 
 targets += vmlinux.o
 
-# module.builtin.modinfo
+# modules.builtin.modinfo
 # ---------------------------------------------------------------------------
 
 OBJCOPYFLAGS_modules.builtin.modinfo := -j .modinfo -O binary
@@ -82,7 +82,7 @@ targets += modules.builtin.modinfo
 modules.builtin.modinfo: vmlinux.o FORCE
 	$(call if_changed,objcopy)
 
-# module.builtin
+# modules.builtin
 # ---------------------------------------------------------------------------
 
 # The second line aids cases where multiple modules share the same object.

scripts/package/kernel.spec

@@ -16,6 +16,7 @@ Source1: config
 Source2: diff.patch
 Provides: kernel-%{KERNELRELEASE}
 BuildRequires: bc binutils bison dwarves
+BuildRequires: (elfutils-devel or libdw-devel)
 BuildRequires: (elfutils-libelf-devel or libelf-devel) flex
 BuildRequires: gcc make openssl openssl-devel perl python3 rsync
 

scripts/package/mkdebian

@@ -210,7 +210,7 @@ Rules-Requires-Root: no
 Build-Depends: debhelper-compat (= 12)
 Build-Depends-Arch: bc, bison, flex,
  gcc-${host_gnu} <!pkg.${sourcename}.nokernelheaders>,
- kmod, libelf-dev:native,
+ kmod, libdw-dev:native, libelf-dev:native,
  libssl-dev:native, libssl-dev <!pkg.${sourcename}.nokernelheaders>,
  python3:native, rsync
 Homepage: https://www.kernel.org/

usr/include/Makefile

@@ -59,6 +59,10 @@ ifeq ($(SRCARCH),arc)
 no-header-test += linux/bpf_perf_event.h
 endif
 
+ifeq ($(SRCARCH),openrisc)
+no-header-test += linux/bpf_perf_event.h
+endif
+
 ifeq ($(SRCARCH),powerpc)
 no-header-test += linux/bpf_perf_event.h
 endif