-Wstringop-overflow is buggy in GCC-11. Therefore, we should disable
this option specifically for that compiler version. To achieve this,
we introduce a new configuration option: GCC11_NO_STRINGOP_OVERFLOW.

The compiler option related to string operation overflow is now managed
under configuration CC_STRINGOP_OVERFLOW. This option is enabled by
default for all other versions of GCC that support it.

Link: https://lore.kernel.org/lkml/b3c99290-40bc-426f-b3d2-1aa903f95c4e@embeddedor.com/
Link: https://lore.kernel.org/lkml/20231128091351.2bfb38dd@canb.auug.org.au/
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/linux-hardening/ZWj1+jkweEDWbmAR@work/
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>

It seems that we have finished addressing all the remaining
issues regarding -Wstringop-overflow. So, we are now in good
shape to enable this compiler option globally.

Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>

Pull Kbuild updates from Masahiro Yamada:

 - Make Kconfig parse the input .config more precisely

 - Support W=c and W=e options for Kconfig

 - Set Kconfig int/hex symbols to zero if the 'default' property is
   missing

 - Add .editorconfig

 - Add scripts/git.orderFile

 - Add a script to detect backward-incompatible changes in UAPI headers

 - Resolve the symlink passed to O= option properly

 - Use the user-supplied mtime for all files in the builtin initramfs,
   which provides better reproducible builds

 - Fix the direct execution of debian/rules for Debian package builds

 - Use build ID instead of the .gnu_debuglink section for the Debian dbg
   package

* tag 'kbuild-v6.8' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (53 commits)
  kbuild: deb-pkg: use debian/<package> for tmpdir
  kbuild: deb-pkg: move 'make headers' to build-arch
  kbuild: deb-pkg: do not search for 'scripts' directory under arch/
  kbuild: deb-pkg: use build ID instead of debug link for dbg package
  kbuild: deb-pkg: use more debhelper commands in builddeb
  kbuild: deb-pkg: remove unneeded '-f $srctree/Makefile' in debian/rules
  kbuild: deb-pkg: allow to run debian/rules from output directory
  kbuild: deb-pkg: set DEB_* variables if debian/rules is directly executed
  kbuild: deb-pkg: squash scripts/package/deb-build-option to debian/rules
  kbuild: deb-pkg: factor out common Make options in debian/rules
  kbuild: deb-pkg: hard-code Build-Depends
  kbuild: deb-pkg: split debian/copyright from the mkdebian script
  gen_init_cpio: Apply mtime supplied by user to all file types
  kbuild: resolve symlinks for O= properly
  docs: dev-tools: Add UAPI checker documentation
  check-uapi: Introduce check-uapi.sh
  scripts: Introduce a default git.orderFile
  kconfig: WERROR unmet symbol dependency
  Add .editorconfig file for basic formatting
  kconfig: Use KCONFIG_CONFIG instead of .config
  ...

Pull non-MM updates from Andrew Morton:
 "Quite a lot of kexec work this time around. Many singleton patches in
  many places. The notable patch series are:

   - nilfs2 folio conversion from Matthew Wilcox in 'nilfs2: Folio
     conversions for file paths'.

   - Additional nilfs2 folio conversion from Ryusuke Konishi in 'nilfs2:
     Folio conversions for directory paths'.

   - IA64 remnant removal in Heiko Carstens's 'Remove unused code after
     IA-64 removal'.

   - Arnd Bergmann has enabled the -Wmissing-prototypes warning
     everywhere in 'Treewide: enable -Wmissing-prototypes'. This had
     some followup fixes:

      - Nathan Chancellor has cleaned up the hexagon build in the series
        'hexagon: Fix up instances of -Wmissing-prototypes'.

      - Nathan also addressed some s390 warnings in 's390: A couple of
        fixes for -Wmissing-prototypes'.

      - Arnd Bergmann addresses the same warnings for MIPS in his series
        'mips: address -Wmissing-prototypes warnings'.

   - Baoquan He has made kexec_file operate in a top-down-fitting manner
     similar to kexec_load in the series 'kexec_file: Load kernel at top
     of system RAM if required'

   - Baoquan He has also added the self-explanatory 'kexec_file: print
     out debugging message if required'.

   - Some checkstack maintenance work from Tiezhu Yang in the series
     'Modify some code about checkstack'.

   - Douglas Anderson has disentangled the watchdog code's logging when
     multiple reports are occurring simultaneously. The series is
     'watchdog: Better handling of concurrent lockups'.

   - Yuntao Wang has contributed some maintenance work on the crash code
     in 'crash: Some cleanups and fixes'"

* tag 'mm-nonmm-stable-2024-01-09-10-33' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (157 commits)
  crash_core: fix and simplify the logic of crash_exclude_mem_range()
  x86/crash: use SZ_1M macro instead of hardcoded value
  x86/crash: remove the unused image parameter from prepare_elf_headers()
  kdump: remove redundant DEFAULT_CRASH_KERNEL_LOW_SIZE
  scripts/decode_stacktrace.sh: strip unexpected CR from lines
  watchdog: if panicking and we dumped everything, don't re-enable dumping
  watchdog/hardlockup: use printk_cpu_sync_get_irqsave() to serialize reporting
  watchdog/softlockup: use printk_cpu_sync_get_irqsave() to serialize reporting
  watchdog/hardlockup: adopt softlockup logic avoiding double-dumps
  kexec_core: fix the assignment to kimage->control_page
  x86/kexec: fix incorrect end address passed to kernel_ident_mapping_init()
  lib/trace_readwrite.c:: replace asm-generic/io with linux/io
  nilfs2: cpfile: fix some kernel-doc warnings
  stacktrace: fix kernel-doc typo
  scripts/checkstack.pl: fix no space expression between sp and offset
  x86/kexec: fix incorrect argument passed to kexec_dprintk()
  x86/kexec: use pr_err() instead of kexec_dprintk() when an error occurs
  nilfs2: add missing set_freezable() for freezable kthread
  kernel: relay: remove relay_file_splice_read dead code, doesn't work
  docs: submit-checklist: remove all of "make namespacecheck"
  ...

Currently, Kbuild follows the logical chain of directories for the O=
option, just like 'cd' (or 'realpath --logical') does.

Example:

    $ mkdir -p /tmp/a /tmp/x/y
    $ ln -s /tmp/x/y /tmp/a/b
    $ realpath /tmp/a/b/..
    /tmp/x
    $ realpath --logical /tmp/a/b/..
    /tmp/a
    $ make O=/tmp/a/b/.. defconfig
    make[1]: Entering directory '/tmp/a'
      [snip]
    make[1]: Leaving directory '/tmp/a'

'make O=/tmp/a/b/.. defconfig' creates the kernel configuration in
/tmp/a instead of /tmp/x despite /tmp/a/b/.. resolves to /tmp/x.

This is because Kbuild internally uses the 'cd ... && pwd' for the
path resolution, but this behavior is not predictable for users.
Additionally, it is not consistent with how the Kbuild handles the
M= option or GNU Make works with 'make -C /tmp/a/b/..'.

Using the physical directory structure for the O= option seems more
reasonable.

The comment says "expand a shell special character '~'", but it has
already been expanded to the home directory in the command line.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nicolas Schier <n.schier@avm.de>