Pull unused tracepoints update from Steven Rostedt:
 "Detect unused tracepoints.

  If a tracepoint is defined but never used (TRACE_EVENT() created but
  no trace_<tracepoint>() called), it can take up to or more than 5K of
  memory each. This can add up as there are around a hundred unused
  tracepoints with various configs. That is 500K of wasted memory.

  Add a make build parameter of "UT=1" to have the build warn if an
  unused tracepoint is detected in the build. This allows detection of
  unused tracepoints to be upstream so that outreachy and the mentoring
  project can have new developers look for fixing them, without having
  these warnings suddenly show up when someone upgrades their kernel.

  When all known unused tracepoints are removed, then the "UT=1" build
  parameter can be removed and unused tracepoints will always warn. This
  will catch new unused tracepoints after the current ones have been
  removed.

  Summary:

   - Separate out elf functions from sorttable.c

     Move out the ELF parsing functions from sorttable.c so that the
     tracing tooling can use it.

   - Add a tracepoint verifier tool to the build process

     If "UT=1" is added to the kernel command line, any unused
     tracepoints will trigger a warning at build time.

   - Do not warn about unused tracepoints for tracepoints that are
     exported

     There are sever cases where a tracepoint is created by the kernel
     and used by modules. Since there's no easy way to detect if these
     are truly unused since the users are in modules, if a tracepoint is
     exported, assume it will eventually be used by a module. Note,
     there's not many exported tracepoints so this should not be a
     problem to ignore them.

   - Have building of modules also detect unused tracepoints

     Do not only check the main vmlinux for unused tracepoints, also
     check modules. If a module is defining a tracepoint it should be
     using it.

   - Add the tracepoint-update program to the ignore file

     The new tracepoint-update program needs to be ignored by git"

* tag 'tracepoints-v6.19' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  scripts: add tracepoint-update to the list of ignores files
  tracing: Add warnings for unused tracepoints for modules
  tracing: Allow tracepoint-update.c to work with modules
  tracepoint: Do not warn for unused event that is exported
  tracing: Add a tracepoint verification check at build time
  sorttable: Move ELF parsing into scripts/elf-parse.[ch]

Pull hardening updates from Kees Cook:

 - string: Add missing kernel-doc return descriptions (Kriish Sharma)

 - Update some mis-typed allocations

   These correct some accidentally wrong types used in allocations (that
   didn't affect the resulting size) that never got picked up from the
   batch I sent a few months ago.

 - Enable GCC diagnostic context for value-tracking warnings

   This results in better GCC diagnostics for the value range tracking,
   so we can get better visibility into where those values are coming
   from when we get out-of-bounds warnings at compile time.

* tag 'hardening-v6.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  kbuild: Enable GCC diagnostic context for value-tracking warnings
  string: Add missing kernel-doc return descriptions
  media: iris: Cast iris_hfi_gen2_get_instance() allocation type
  drm/plane: Remove const qualifier from plane->modifiers allocation type
  comedi: Adjust range_table_list allocation type

Pull Kbuild updates from Nicolas Schier:

  - Enable -fms-extensions, allowing anonymous use of tagged struct or
    union in struct/union (tag kbuild-ms-extensions-6.19). An exemplary
    conversion patch is added here, too (btrfs).

    [ Editor's note: the core of this actually came in early through a
      shared branch and a few other trees    - Linus ]

  - Introduce architecture-specific CC_CAN_LINK and flags for userprogs

  - Add new packaging target 'modules-cpio-pkg' for building a initramfs
    cpio w/ kmods

  - Handle included .c files in gen_compile_commands

  - Minor kbuild changes:
     - Use objtree for module signing key path, fixing oot kmod signing
     - Improve documentation of KBUILD_BUILD_TIMESTAMP
     - Reuse KBUILD_USERCFLAGS for UAPI, instead of defining twice
     - Rename scripts/Makefile.extrawarn to Makefile.warn
     - Drop obsolete types.h check from headers_check.pl
     - Remove outdated config leak ignore entries

* tag 'kbuild-6.19-1' of git://git.kernel.org/pub/scm/linux/kernel/git/kbuild/linux:
  kbuild: add target to build a cpio containing modules
  initramfs: add gen_init_cpio to hostprogs unconditionally
  kbuild: allow architectures to override CC_CAN_LINK
  init: deduplicate cc-can-link.sh invocations
  kbuild: don't enable CC_CAN_LINK if the dummy program generates warnings
  scripts: headers_install.sh: Remove two outdated config leak ignore entries
  scripts/clang-tools: Handle included .c files in gen_compile_commands
  kbuild: uapi: Drop types.h check from headers_check.pl
  kbuild: Rename Makefile.extrawarn to Makefile.warn
  MAINTAINERS, .mailmap: Update mail address for Nicolas Schier
  kbuild: uapi: reuse KBUILD_USERCFLAGS
  kbuild: doc: improve KBUILD_BUILD_TIMESTAMP documentation
  kbuild: Use objtree for module signing key path
  btrfs: send: make use of -fms-extensions for defining struct fs_path

Pull Rust updates from Miguel Ojeda:
 "Toolchain and infrastructure:

   - Add support for 'syn'.

     Syn is a parsing library for parsing a stream of Rust tokens into a
     syntax tree of Rust source code.

     Currently this library is geared toward use in Rust procedural
     macros, but contains some APIs that may be useful more generally.

     'syn' allows us to greatly simplify writing complex macros such as
     'pin-init' (Benno has already prepared the 'syn'-based version). We
     will use it in the 'macros' crate too.

     'syn' is the most downloaded Rust crate (according to crates.io),
     and it is also used by the Rust compiler itself. While the amount
     of code is substantial, there should not be many updates needed for
     these crates, and even if there are, they should not be too big,
     e.g. +7k -3k lines across the 3 crates in the last year.

     'syn' requires two smaller dependencies: 'quote' and 'proc-macro2'.
     I only modified their code to remove a third dependency
     ('unicode-ident') and to add the SPDX identifiers. The code can be
     easily verified to exactly match upstream with the provided
     scripts.

     They are all licensed under "Apache-2.0 OR MIT", like the other
     vendored 'alloc' crate we had for a while.

     Please see the merge commit with the cover letter for more context.

   - Allow 'unreachable_pub' and 'clippy::disallowed_names' for
     doctests.

     Examples (i.e. doctests) may want to do things like show public
     items and use names such as 'foo'.

     Nevertheless, we still try to keep examples as close to real code
     as possible (this is part of why running Clippy on doctests is
     important for us, e.g. for safety comments, which userspace Rust
     does not support yet but we are stricter).

  'kernel' crate:

   - Replace our custom 'CStr' type with 'core::ffi::CStr'.

     Using the standard library type reduces our custom code footprint,
     and we retain needed custom functionality through an extension
     trait and a new 'fmt!' macro which replaces the previous 'core'
     import.

     This started in 6.17 and continued in 6.18, and we finally land the
     replacement now. This required quite some stamina from Tamir, who
     split the changes in steps to prepare for the flag day change here.

   - Replace 'kernel::c_str!' with C string literals.

     C string literals were added in Rust 1.77, which produce '&CStr's
     (the 'core' one), so now we can write:

         c"hi"

     instead of:

         c_str!("hi")

   - Add 'num' module for numerical features.

     It includes the 'Integer' trait, implemented for all primitive
     integer types.

     It also includes the 'Bounded' integer wrapping type: an integer
     value that requires only the 'N' least significant bits of the
     wrapped type to be encoded:

         // An unsigned 8-bit integer, of which only the 4 LSBs are used.
         let v = Bounded::<u8, 4>::new::<15>();
         assert_eq!(v.get(), 15);

     'Bounded' is useful to e.g. enforce guarantees when working with
     bitfields that have an arbitrary number of bits.

     Values can also be constructed from simple non-constant expressions
     or, for more complex ones, validated at runtime.

     'Bounded' also comes with comparison and arithmetic operations
     (with both their backing type and other 'Bounded's with a
     compatible backing type), casts to change the backing type,
     extending/shrinking and infallible/fallible conversions from/to
     primitives as applicable.

   - 'rbtree' module: add immutable cursor ('Cursor').

     It enables to use just an immutable tree reference where
     appropriate. The existing fully-featured mutable cursor is renamed
     to 'CursorMut'.

  kallsyms:

   - Fix wrong "big" kernel symbol type read from procfs.

  'pin-init' crate:

   - A couple minor fixes (Benno asked me to pick these patches up for
     him this cycle).

  Documentation:

   - Quick Start guide: add Debian 13 (Trixie).

     Debian Stable is now able to build Linux, since Debian 13 (released
     2025-08-09) packages Rust 1.85.0, which is recent enough.

     We are planning to propose that the minimum supported Rust version
     in Linux follows Debian Stable releases, with Debian 13 being the
     first one we upgrade to, i.e. Rust 1.85.

  MAINTAINERS:

   - Add entry for the new 'num' module.

   - Remove Alex as Rust maintainer: he hasn't had the time to
     contribute for a few years now, so it is a no-op change in
     practice.

  And a few other cleanups and improvements"

* tag 'rust-6.19' of git://git.kernel.org/pub/scm/linux/kernel/git/ojeda/linux: (53 commits)
  rust: macros: support `proc-macro2`, `quote` and `syn`
  rust: syn: enable support in kbuild
  rust: syn: add `README.md`
  rust: syn: remove `unicode-ident` dependency
  rust: syn: add SPDX License Identifiers
  rust: syn: import crate
  rust: quote: enable support in kbuild
  rust: quote: add `README.md`
  rust: quote: add SPDX License Identifiers
  rust: quote: import crate
  rust: proc-macro2: enable support in kbuild
  rust: proc-macro2: add `README.md`
  rust: proc-macro2: remove `unicode_ident` dependency
  rust: proc-macro2: add SPDX License Identifiers
  rust: proc-macro2: import crate
  rust: kbuild: support using libraries in `rustc_procmacro`
  rust: kbuild: support skipping flags in `rustc_test_library`
  rust: kbuild: add proc macro library support
  rust: kbuild: simplify `--cfg` handling
  rust: kbuild: introduce `core-flags` and `core-skip_flags`
  ...

Pull documentation updates from Jonathan Corbet:
 "This has been another busy cycle for documentation, with a lot of
  build-system thrashing. That work should slow down from here on out.

   - The various scripts and tools for documentation were spread out in
     several directories; now they are (almost) all coalesced under
     tools/docs/. The holdout is the kernel-doc script, which cannot be
     easily moved without some further thought.

   - As the amount of Python code increases, we are accumulating modules
     that are imported by multiple programs. These modules have been
     pulled together under tools/lib/python/ -- at least, for
     documentation-related programs. There is other Python code in the
     tree that might eventually want to move toward this organization.

   - The Perl kernel-doc.pl script has been removed. It is no longer
     used by default, and nobody has missed it, least of all anybody who
     actually had to look at it.

   - The docs build was controlled by a complex mess of makefilese that
     few dared to touch. Mauro has moved that logic into a new program
     (tools/docs/sphinx-build-wrapper) that, with any luck at all, will
     be far easier to understand and maintain.

   - The get_feat.pl program, used to access information under
     Documentation/features/, has been rewritten in Python, bringing an
     end to the use of Perl in the docs subsystem.

   - The top-level README file has been reorganized into a more
     reader-friendly presentation.

   - A lot of Chinese translation additions

   - Typo fixes and documentation updates as usual"

* tag 'docs-6.19' of git://git.lwn.net/linux: (164 commits)
  docs: makefile: move rustdoc check to the build wrapper
  README: restructure with role-based documentation and guidelines
  docs: kdoc: various fixes for grammar, spelling, punctuation
  docs: kdoc_parser: use '@' for Excess enum value
  docs: submitting-patches: Clarify that removal of Acks needs explanation too
  docs: kdoc_parser: add data/function attributes to ignore
  docs: MAINTAINERS: update Mauro's files/paths
  docs/zh_CN: Add wd719x.rst translation
  docs/zh_CN: Add libsas.rst translation
  get_feat.pl: remove it, as it got replaced by get_feat.py
  Documentation/sphinx/kernel_feat.py: use class directly
  tools/docs/get_feat.py: convert get_feat.pl to Python
  Documentation/admin-guide: fix typo and comment in cscope example
  docs/zh_CN: Add data-integrity.rst translation
  docs/zh_CN: Add blk-mq.rst translation
  docs/zh_CN: Add block/index.rst translation
  docs/zh_CN: Update the Chinese translation of kbuild.rst
  docs: bring some order to our Python module hierarchy
  docs: Move the python libraries to tools/lib/python
  Documentation/kernel-parameters: Move the kernel build options
  ...

Pull misc vfs updates from Christian Brauner:
 "Features:

   - Cheaper MAY_EXEC handling for path lookup. This elides MAY_WRITE
     permission checks during path lookup and adds the
     IOP_FASTPERM_MAY_EXEC flag so filesystems like btrfs can avoid
     expensive permission work.

   - Hide dentry_cache behind runtime const machinery.

   - Add German Maglione as virtiofs co-maintainer.

  Cleanups:

   - Tidy up and inline step_into() and walk_component() for improved
     code generation.

   - Re-enable IOCB_NOWAIT writes to files. This refactors file
     timestamp update logic, fixing a layering bypass in btrfs when
     updating timestamps on device files and improving FMODE_NOCMTIME
     handling in VFS now that nfsd started using it.

   - Path lookup optimizations extracting slowpaths into dedicated
     routines and adding branch prediction hints for mntput_no_expire(),
     fd_install(), lookup_slow(), and various other hot paths.

   - Enable clang's -fms-extensions flag, requiring a JFS rename to
     avoid conflicts.

   - Remove spurious exports in fs/file_attr.c.

   - Stop duplicating union pipe_index declaration. This depends on the
     shared kbuild branch that brings in -fms-extensions support which
     is merged into this branch.

   - Use MD5 library instead of crypto_shash in ecryptfs.

   - Use largest_zero_folio() in iomap_dio_zero().

   - Replace simple_strtol/strtoul with kstrtoint/kstrtouint in init and
     initrd code.

   - Various typo fixes.

  Fixes:

   - Fix emergency sync for btrfs. Btrfs requires an explicit sync_fs()
     call with wait == 1 to commit super blocks. The emergency sync path
     never passed this, leaving btrfs data uncommitted during emergency
     sync.

   - Use local kmap in watch_queue's post_one_notification().

   - Add hint prints in sb_set_blocksize() for LBS dependency on THP"

* tag 'vfs-6.19-rc1.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (35 commits)
  MAINTAINERS: add German Maglione as virtiofs co-maintainer
  fs: inline step_into() and walk_component()
  fs: tidy up step_into() & friends before inlining
  orangefs: use inode_update_timestamps directly
  btrfs: fix the comment on btrfs_update_time
  btrfs: use vfs_utimes to update file timestamps
  fs: export vfs_utimes
  fs: lift the FMODE_NOCMTIME check into file_update_time_flags
  fs: refactor file timestamp update logic
  include/linux/fs.h: trivial fix: regualr -> regular
  fs/splice.c: trivial fix: pipes -> pipe's
  fs: mark lookup_slow() as noinline
  fs: add predicts based on nd->depth
  fs: move mntput_no_expire() slowpath into a dedicated routine
  fs: remove spurious exports in fs/file_attr.c
  watch_queue: Use local kmap in post_one_notification()
  fs: touch up predicts in path lookup
  fs: move fd_install() slowpath into a dedicated routine and provide commentary
  fs: hide dentry_cache behind runtime const machinery
  fs: touch predicts in do_dentry_open()
  ...

Enable GCC 16's coming "-fdiagnostics-show-context=N" option[1] to
provide enhanced diagnostic information for value-tracking warnings,
which displays the control flow chain leading to the diagnostic. This
covers our existing use of -Wrestrict and -Wstringop-overread, and
gets us closer to enabling -Warray-bounds, -Wstringop-overflow, and
-Wstringop-truncation, so we can track the rationale for the warning,
letting us more quickly identify actual issues vs what have looked in
the past like false positives. Fixes based on this work have already
been landing, e.g.:

  4a6f18f28627 ("net/mlx4_core: Avoid impossible mlx4_db_alloc() order value")
  8a39f1c870e9 ("ovl: Check for NULL d_inode() in ovl_dentry_upper()")
  e5f7e4e0a445 ("drm/amdgpu/atom: Work around vbios NULL offset false positive")

The context depth ("=N") provides the immediate decision path that led
to the problematic code location, showing conditional checks and branch
decisions that caused the warning. This will help us understand why
GCC's value-tracking analysis triggered the warning and makes it easier
to determine whether warnings are legitimate issues or false positives.

For example, an array bounds warning will now show the conditional
statements (like "if (i >= 4)") that established the out-of-bounds access
range, directly connecting the control flow to the warning location.
This is particularly valuable when GCC's interprocedural analysis can
generate warnings that are difficult to understand without seeing the
inferred control flow.

While my testing has shown that "=1" reports enough for finding
the origin of most bounds issues, I have used "=2" here just to be
conservative. Build time measurements with this option off, =1, and =2
are all with noise of each other, so there seems to be no harm in "turning
it up". If we need to, we can make this value configurable in the future.

Link: https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=6faa3cfe60ff9769d1bebfffdd2c7325217d7389 [1]
Reviewed-by: Miguel Ojeda <ojeda@kernel.org>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Link: https://patch.msgid.link/20251121184342.it.626-kees@kernel.org
Signed-off-by: Kees Cook <kees@kernel.org>