Kbuild fixes for v6.6 (2nd)

- Fix the module compression with xz so the in-kernel decompressor works
 
  - Document a kconfig idiom to express an optional dependency between
    modules
 
  - Make modpost, when W=1 is given, detect broken drivers that reference
    .exit.* sections
 
  - Remove unused code
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Merge tag 'kbuild-fixes-v6.6-2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

Pull Kbuild fixes from Masahiro Yamada:

 - Fix the module compression with xz so the in-kernel decompressor
   works

 - Document a kconfig idiom to express an optional dependency between
   modules

 - Make modpost, when W=1 is given, detect broken drivers that reference
   .exit.* sections

 - Remove unused code

* tag 'kbuild-fixes-v6.6-2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild:
  kbuild: remove stale code for 'source' symlink in packaging scripts
  modpost: Don't let "driver"s reference .exit.*
  vmlinux.lds.h: remove unused CPU_KEEP and CPU_DISCARD macros
  modpost: add missing else to the "of" check
  Documentation: kbuild: explain handling optional dependencies
  kbuild: Use CRC32 and a 1MiB dictionary for XZ compressed modules

Documentation/kbuild/kconfig-language.rst

@@ -573,6 +573,32 @@ above, leading to:
 	bool "Support for foo hardware"
 	depends on ARCH_FOO_VENDOR || COMPILE_TEST
 
+Optional dependencies
+~~~~~~~~~~~~~~~~~~~~~
+
+Some drivers are able to optionally use a feature from another module
+or build cleanly with that module disabled, but cause a link failure
+when trying to use that loadable module from a built-in driver.
+
+The most common way to express this optional dependency in Kconfig logic
+uses the slightly counterintuitive::
+
+  config FOO
+	tristate "Support for foo hardware"
+	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.
+For a more formalized approach if there are multiple drivers that have
+the same dependency, a helper symbol can be used, like::
+
+  config FOO
+	tristate "Support for foo hardware"
+	depends on BAR_OPTIONAL
+
+  config BAR_OPTIONAL
+	def_tristate BAR || !BAR
+
 Kconfig recursive dependency limitations
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 

include/asm-generic/vmlinux.lds.h

@@ -138,13 +138,6 @@
  * are handled as text/data or they can be discarded (which
  * often happens at runtime)
  */
-#ifdef CONFIG_HOTPLUG_CPU
-#define CPU_KEEP(sec)    *(.cpu##sec)
-#define CPU_DISCARD(sec)
-#else
-#define CPU_KEEP(sec)
-#define CPU_DISCARD(sec) *(.cpu##sec)
-#endif
 
 #if defined(CONFIG_MEMORY_HOTPLUG)
 #define MEM_KEEP(sec)    *(.mem##sec)

scripts/Makefile.modinst

@@ -144,7 +144,7 @@ endif
 quiet_cmd_gzip = GZIP    $@
       cmd_gzip = $(KGZIP) -n -f $<
 quiet_cmd_xz = XZ      $@
-      cmd_xz = $(XZ) --lzma2=dict=2MiB -f $<
+      cmd_xz = $(XZ) --check=crc32 --lzma2=dict=1MiB -f $<
 quiet_cmd_zstd = ZSTD    $@
       cmd_zstd = $(ZSTD) -T0 --rm -f -q $<
 

scripts/mod/file2alias.c

@@ -1604,7 +1604,7 @@ void handle_moddevtable(struct module *mod, struct elf_info *info,
 	/* First handle the "special" cases */
 	if (sym_is(name, namelen, "usb"))
 		do_usb_table(symval, sym->st_size, mod);
-	if (sym_is(name, namelen, "of"))
+	else if (sym_is(name, namelen, "of"))
 		do_of_table(symval, sym->st_size, mod);
 	else if (sym_is(name, namelen, "pnp"))
 		do_pnp_device_entry(symval, sym->st_size, mod);

scripts/mod/modpost.c

@@ -1015,9 +1015,20 @@ static int secref_whitelist(const char *fromsec, const char *fromsym,
 				    "*_console")))
 		return 0;
 
-	/* symbols in data sections that may refer to meminit/exit sections */
+	/* symbols in data sections that may refer to meminit sections */
 	if (match(fromsec, PATTERNS(DATA_SECTIONS)) &&
-	    match(tosec, PATTERNS(ALL_XXXINIT_SECTIONS, ALL_EXIT_SECTIONS)) &&
+	    match(tosec, PATTERNS(ALL_XXXINIT_SECTIONS, ALL_XXXEXIT_SECTIONS)) &&
+	    match(fromsym, PATTERNS("*driver")))
+		return 0;
+
+	/*
+	 * symbols in data sections must not refer to .exit.*, but there are
+	 * quite a few offenders, so hide these unless for W=1 builds until
+	 * these are fixed.
+	 */
+	if (!extra_warn &&
+	    match(fromsec, PATTERNS(DATA_SECTIONS)) &&
+	    match(tosec, PATTERNS(EXIT_SECTIONS)) &&
 	    match(fromsym, PATTERNS("*driver")))
 		return 0;
 

scripts/package/builddeb

@@ -64,7 +64,6 @@ install_linux_image () {
 
 	${MAKE} -f ${srctree}/Makefile INSTALL_MOD_PATH="${pdir}" modules_install
 	rm -f "${pdir}/lib/modules/${KERNELRELEASE}/build"
-	rm -f "${pdir}/lib/modules/${KERNELRELEASE}/source"
 
 	# Install the kernel
 	if [ "${ARCH}" = um ] ; then

scripts/package/kernel.spec

@@ -68,7 +68,6 @@ cp $(%{make} %{makeflags} -s image_name) %{buildroot}/boot/vmlinuz-%{KERNELRELEA
 cp System.map %{buildroot}/boot/System.map-%{KERNELRELEASE}
 cp .config %{buildroot}/boot/config-%{KERNELRELEASE}
 ln -fns /usr/src/kernels/%{KERNELRELEASE} %{buildroot}/lib/modules/%{KERNELRELEASE}/build
-ln -fns /usr/src/kernels/%{KERNELRELEASE} %{buildroot}/lib/modules/%{KERNELRELEASE}/source
 %if %{with_devel}
 %{make} %{makeflags} run-command KBUILD_RUN_COMMAND='${srctree}/scripts/package/install-extmod-build %{buildroot}/usr/src/kernels/%{KERNELRELEASE}'
 %endif
@@ -101,7 +100,6 @@ fi
 %defattr (-, root, root)
 /lib/modules/%{KERNELRELEASE}
 %exclude /lib/modules/%{KERNELRELEASE}/build
-%exclude /lib/modules/%{KERNELRELEASE}/source
 /boot/*
 
 %files headers
@@ -113,5 +111,4 @@ fi
 %defattr (-, root, root)
 /usr/src/kernels/%{KERNELRELEASE}
 /lib/modules/%{KERNELRELEASE}/build
-/lib/modules/%{KERNELRELEASE}/source
 %endif