Merge tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Don't destroy user event fields when removal fails

   User event fields are destroyed before the event is removed from
   visibility. But that can fail leaving the still visible event with no
   fields. Move the destroying of the fields to after the event is
   successfully removed from visibility.

 - Initialize function graph state is fork before calling
   copy_exec_state()

   For non-CLONE_VM forks, copy_exec_state() allocates a new
   task_exec_state. If that allocation fails, ftrace_graph_exit_task()
   will free the tasks ret_stack pointer. Since that pointer is still
   using the parent's ret_stack, it mistakenly frees the parent's
   pointer too.

   Call ftrace_graph_init() on the task first which will NULL out the
   new tasks's ret_stack and if the copy fails, it will not free
   anything.

 - Remove FGRAPH_MAX_INDEX

   The macro FGRAPH_MAX_INDEX was added but never used. Remove it.

 - Save ent_size in function graph printing of nested functions

   The function graph tracer needs to look at the next event to see if
   the next event is the return of the current function entry. If it is,
   it prints a single line:

	ktime_get();

   Otherwise it prints it like a nested function:

	tick_nohz_irq_exit() {
	    ktime_get();
	    kcpustat_irq_exit();
	}

   In order to look at the next event, it must save the current event so
   that it has the information to print from it. It saves the event in
   the iterator descriptor called "ent". What it doesn't save is the
   ent_size of the event which is now used to know if the function graph
   arguments are to be printed. The peek doesn't save the size so the
   size used happens to be that of the size of the last event that was
   seen.

   Save the entry event size in the iterator descriptor so that the
   correct size is used.

 - Fix several errors with freeing data in the histogram code

   The histogram code had a lot of leaked or or incorrect accounting
   when failures happen. Correct them.

 - Fix histogram regression of .percent and .graph modifiers

   Up until 6.3 histogram values could have "percent" or "graph"
   modifiers that changed how they were printed. But a change that added
   restricting histograms values from being strings, stack traces and
   other modifiers inadvertently prevented them from using the percent
   and graph modifiers, which were legal use cases for values.

   Put back the percent and graph modifiers.

 - Fix various typos in the comments

 - Set the trace_clock before initializing a histogram with clock
   argument

   The histogram API allows the user to specific which trace clock to
   use via a "clock=" string. The histogram is set up first before the
   clock is checked. If the passed in clock is not valid, it exits
   without fully fixing up the histogram leaving it on the list and a
   use-after-free can trigger.

   Update the clock argument first and if it fails then exit gracefully
   before the histogram trigger is placed on any lists.

 - Restore :mod: trailer after parsing in ftrace_set_clr_event

   The function ftrace_set_clr_event() modifies the parse string and
   needs to put it back to what was passed in. It searches for ":mod:"
   via a strsep() but fails to put back the first ':' in the string.

   Add back the ':' in the passed in string.

 - Take trace_array reference when opening a tracer options file

   The options files are dynamically created and some tracers add their
   own options. When a tracer adds their own list of options, the
   trace_array holding them has an array to hold the list of options for
   each tracer. This array increases in size via a krealloc(), and the
   new entry gets a newly allocated array to hold the options of the new
   tracer being added.

   The element in each entry of the tracer's option array holds a
   pointer back to the trace_array, a pointer to the tracer it is
   associated to, a pointer to the flags of the option.

   The issue is that these arrays are freed when the trace_array is
   freed when its instance it represents is removed from the instances
   directory. There's a race that an open of one of these options files
   can happen when the instance is being removed.

   Add a new helper function to be called by the open function of the
   options file to iterate all existing trace_arrays under a lock and
   find the one that has the given option element in one of it's tracer
   arrays. If found, then update the associated trace_array's reference
   counter to keep it from being freed. If not found, have the open call
   return -ENODEV.

 - Disable interrupts when acquiring the lock in rb_wake_up_waiters()

   The function rb_wake_up_waiters() assumes it will be called in
   interrupt context and does not disable irqs when taking
   cpu_buffer->reader_lock, which can be called in hard interrupt
   context. The issue is in PREEMPT_RT, this function is called in
   thread context leaving this lock open to a deadlock.

   Take the lock with interrupts disabled.

 - Use rcu_assign_pointer() for tmp_ops filter hash

   The tmp_ops used in update_ftrace_direct_mod() assigns its
   filter_hash field directly, but that field is annotated as __rcu and
   sparse complains. Assign it with rcu_assign_pointer()

 - Fix use-after-free in enable_trigger_private_data_free()

   The trace_event_call is accessed through the event_trigger_data's
   trace_event_file pointer to put the trace_event_call on freeing. The
   issue is that the trace_event_file data may have been freed already
   causing a use-after-free. Add a field to the event_trigger_data that
   points directly to the trace_event_call so that it can decrement its
   reference directly without needing to go through the
   trace_event_file.

 - Fix accounting of buffer data remote headers

   trace_buffer_desc_size() and trace_remote_alloc_buffer() undercount
   the number of pages is needed for the asked for size as it doesn't
   take into account the meta data on each page. Add a helper function
   to do the calculation properly and use that in these functions.

 - Catch nr_page_va overflow in ring_buffer_desc sizing

   The number of pages per remote ring buffer is capped by
   ring_buffer_desc::nr_page_va (32 bits). A buffer_size large enough to
   overflow that field would silently allocate a descriptor smaller than
   what was asked for.

 - Do not resize the subbuf order if any per_cpu buffer is disabled

   The mmapping of ring buffers disables resizing the subbuffers, but it
   is done per-cpu whereas the subbuf size change is done for all the
   per_cpu buffers under the buffer->mutex. It could change the size of
   some while the mapping is happening on others. Have the resize of the
   subbuf order check all the per_cpu buffers under the lock to see if
   any of them is disabled before starting and causing an inconsistency
   between buffers that are being mapped.

* tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (25 commits)
  ring-buffer: Check resize_disabled before publishing the new subbuf order
  tracing/remotes: Catch nr_page_va overflow in ring_buffer_desc sizing
  tracing/remotes: Account for ring buffer page header in size calculation
  tracing: Don't dereference trace_event_file in deferred trigger free
  ftrace: Use rcu_assign_pointer() for tmp_ops filter hash
  ring-buffer: Acquire the lock with irqsave in rb_wake_up_waiters()
  tracing: Take trace_array reference when opening a tracer options file
  tracing: Fix ring_buffer_read_page_size() kernel-doc
  tracing: Restore :mod: trailer after parsing in ftrace_set_clr_event()
  tracing: Fix memory corruption from a "STACKTRACE" histogram key
  tracing: Fix memory corruption from the histogram stacktrace modifier
  tracing: Undo the registration when enabling the histogram trigger fails
  tracing: Take the reference before publishing the named histogram trigger
  tracing: Set the trace clock before registering the histogram trigger
  tracing: Fix typo "preceeded" in comment
  tracing: Fix typo "availabe" in comment
  tracing: Let histogram values keep the percent and graph modifiers
  tracing: Keep the entry count when the histogram stats allocation fails
  tracing: Free histogram the field rejected for a bad modifier
  tracing: Free histogram the var ref when its initialization fails
  ...

1 files changed, 381 insertions, 0 deletions

diff --git a/Documentation/process/kernel-docs.rst b/Documentation/process/kernel-docs.rst
new file mode 100644
index 000000000..c67ac12cf
--- /dev/null
+++ b/Documentation/process/kernel-docs.rst
@@ -0,0 +1,381 @@
+.. _kernel_docs:
+
+Index of Further Kernel Documentation
+=====================================
+
+The need for a document like this one became apparent in the linux-kernel
+mailing list as the same questions, asking for pointers to information,
+appeared again and again.
+
+Fortunately, as more and more people get to GNU/Linux, more and more get
+interested in the Kernel. But reading the sources is not always enough. It
+is easy to understand the code, but miss the concepts, the philosophy and
+design decisions behind this code.
+
+Unfortunately, not many documents are available for beginners to start.
+And, even if they exist, there was no "well-known" place which kept track
+of them. These lines try to cover this lack.
+
+PLEASE, if you know any paper not listed here or write a new document,
+include a reference to it here, following the kernel's patch submission
+process. Any corrections, ideas or comments are also welcome.
+
+All documents are cataloged with the following fields: the document's
+"Title", the "Author"/s, the "URL" where they can be found, some "Keywords"
+helpful when searching for specific topics, and a brief "Description" of
+the Document.
+
+.. note::
+
+   The documents on each section of this document are ordered by its
+   published date, from the newest to the oldest. The maintainer(s) should
+   periodically retire resources as they become obsolete or outdated; with
+   the exception of foundational books.
+
+Docs at the Linux Kernel tree
+-----------------------------
+
+The Sphinx books should be built with ``make {htmldocs | pdfdocs | epubdocs}``.
+
+    * Name: **linux/Documentation**
+
+      :Author: Many.
+      :Location: Documentation/
+      :Keywords: text files, Sphinx.
+      :Description: Documentation that comes with the kernel sources,
+        inside the Documentation directory. Some pages from this document
+        (including this document itself) have been moved there, and might
+        be more up to date than the web version.
+
+On-line docs
+------------
+
+    * Title: **Linux Kernel Mailing List Glossary**
+
+      :Author: various
+      :URL: https://kernelnewbies.org/KernelGlossary
+      :Date: rolling version
+      :Keywords: glossary, terms, linux-kernel.
+      :Description: From the introduction: "This glossary is intended as
+        a brief description of some of the acronyms and terms you may hear
+        during discussion of the Linux kernel".
+
+    * Title: **The Linux Kernel Module Programming Guide**
+
+      :Author: Peter Jay Salzman, Michael Burian, Ori Pomerantz, Bob Mottram,
+        Jim Huang.
+      :URL: https://sysprog21.github.io/lkmpg/
+      :Date: 2021
+      :Keywords: modules, GPL book, /proc, ioctls, system calls,
+        interrupt handlers .
+      :Description: A very nice GPL book on the topic of modules
+        programming. Lots of examples. Currently the new version is being
+        actively maintained at https://github.com/sysprog21/lkmpg.
+
+Published books
+---------------
+
+    * Title: **The Linux Memory Manager**
+
+      :Author: Lorenzo Stoakes
+      :Publisher: No Starch Press
+      :Date: February 2025
+      :Pages: 1300
+      :ISBN: 978-1718504462
+      :Notes: Memory management. Full draft available as early access for
+              pre-order, full release scheduled for Fall 2025. See
+              https://nostarch.com/linux-memory-manager for further info.
+
+    * Title: **Practical Linux System Administration: A Guide to Installation, Configuration, and Management, 1st Edition**
+
+      :Author: Kenneth Hess
+      :Publisher: O'Reilly Media
+      :Date: May, 2023
+      :Pages: 246
+      :ISBN: 978-1098109035
+      :Notes: System administration
+
+    * Title: **Linux Kernel Debugging: Leverage proven tools and advanced techniques to effectively debug Linux kernels and kernel modules**
+
+      :Author: Kaiwan N Billimoria
+      :Publisher: Packt Publishing Ltd
+      :Date: August, 2022
+      :Pages: 638
+      :ISBN: 978-1801075039
+      :Notes: Debugging book
+
+    * Title: **Linux Kernel Programming: A Comprehensive Guide to Kernel Internals, Writing Kernel Modules, and Kernel Synchronization**
+
+      :Author: Kaiwan N Billimoria
+      :Publisher: Packt Publishing Ltd
+      :Date: March, 2021 (Second Edition published in 2024)
+      :Pages: 754
+      :ISBN: 978-1789953435 (Second Edition ISBN is 978-1803232225)
+
+    * Title: **Linux Kernel Programming Part 2 - Char Device Drivers and Kernel Synchronization: Create user-kernel interfaces, work with peripheral I/O, and handle hardware interrupts**
+
+      :Author: Kaiwan N Billimoria
+      :Publisher: Packt Publishing Ltd
+      :Date: March, 2021
+      :Pages: 452
+      :ISBN: 978-1801079518
+
+    * Title: **Linux System Programming: Talking Directly to the Kernel and C Library**
+
+      :Author: Robert Love
+      :Publisher: O'Reilly Media
+      :Date: June, 2013
+      :Pages: 456
+      :ISBN: 978-1449339531
+      :Notes: Foundational book
+
+    * Title: **Linux Kernel Development, 3rd Edition**
+
+      :Author: Robert Love
+      :Publisher: Addison-Wesley
+      :Date: July, 2010
+      :Pages: 440
+      :ISBN: 978-0672329463
+      :Notes: Foundational book
+
+.. _ldd3_published:
+
+    * Title: **Linux Device Drivers, 3rd Edition**
+
+      :Authors: Jonathan Corbet, Alessandro Rubini, and Greg Kroah-Hartman
+      :Publisher: O'Reilly & Associates
+      :Date: 2005
+      :Pages: 636
+      :ISBN: 0-596-00590-3
+      :Notes: Foundational book. Further information in
+        http://www.oreilly.com/catalog/linuxdrive3/
+        PDF format, URL: https://lwn.net/Kernel/LDD3/
+
+    * Title: **The Design of the UNIX Operating System**
+
+      :Author: Maurice J. Bach
+      :Publisher: Prentice Hall
+      :Date: 1986
+      :Pages: 471
+      :ISBN: 0-13-201757-1
+      :Notes: Foundational book
+
+Miscellaneous
+-------------
+
+    * Name: **Cross-Referencing Linux**
+
+      :URL: https://elixir.bootlin.com/
+      :Keywords: Browsing source code.
+      :Description: Another web-based Linux kernel source code browser.
+        Lots of cross references to variables and functions. You can see
+        where they are defined and where they are used.
+
+    * Name: **Linux Weekly News**
+
+      :URL: https://lwn.net
+      :Keywords: latest kernel news.
+      :Description: The title says it all. There's a fixed kernel section
+        summarizing developers' work, bug fixes, new features and versions
+        produced during the week.
+
+    * Name: **The home page of Linux-MM**
+
+      :Author: The Linux-MM team.
+      :URL: https://linux-mm.org/
+      :Keywords: memory management, Linux-MM, mm patches, TODO, docs,
+        mailing list.
+      :Description: Site devoted to Linux Memory Management development.
+        Memory related patches, HOWTOs, links, mm developers... Don't miss
+        it if you are interested in memory management development!
+
+    * Name: **Kernel Newbies IRC Channel and Website**
+
+      :URL: https://www.kernelnewbies.org
+      :Keywords: IRC, newbies, channel, asking doubts.
+      :Description: #kernelnewbies on irc.oftc.net.
+        #kernelnewbies is an IRC network dedicated to the 'newbie'
+        kernel hacker. The audience mostly consists of people who are
+        learning about the kernel, working on kernel projects or
+        professional kernel hackers that want to help less seasoned kernel
+        people.
+        #kernelnewbies is on the OFTC IRC Network.
+        Try irc.oftc.net as your server and then /join #kernelnewbies.
+        The kernelnewbies website also hosts articles, documents, FAQs...
+
+    * Name: **linux-kernel mailing list archives and search engines**
+
+      :URL: https://subspace.kernel.org
+      :URL: https://lore.kernel.org
+      :Keywords: linux-kernel, archives, search.
+      :Description: Some of the linux-kernel mailing list archivers. If
+        you have a better/another one, please let me know.
+
+    * Name: **The Linux Foundation YouTube channel**
+
+      :URL: https://www.youtube.com/user/thelinuxfoundation
+      :Keywords: linux, videos, linux-foundation, youtube.
+      :Description: The Linux Foundation uploads video recordings of their
+        collaborative events, Linux conferences including LinuxCon, and
+        other original research and content related to Linux and software
+        development.
+
+Rust
+----
+
+    * Title: **Rust for Linux**
+
+      :Author: various
+      :URL: https://rust-for-linux.com/
+      :Date: rolling version
+      :Keywords: glossary, terms, linux-kernel, rust.
+      :Description: From the website: "Rust for Linux is the project adding
+        support for the Rust language to the Linux kernel. This website is
+        intended as a hub of links, documentation and resources related to
+        the project".
+
+    * Title: **Learn Rust the Dangerous Way**
+
+      :Author: Cliff L. Biffle
+      :URL: https://cliffle.com/p/dangerust/
+      :Date: Accessed Sep 11 2024
+      :Keywords: rust, blog.
+      :Description: From the website: "LRtDW is a series of articles
+        putting Rust features in context for low-level C programmers who
+        maybe don’t have a formal CS background — the sort of people who
+        work on firmware, game engines, OS kernels, and the like.
+        Basically, people like me.". It illustrates line-by-line
+        conversions from C to Rust.
+
+    * Title: **The Rust Book**
+
+      :Author: Steve Klabnik and Carol Nichols, with contributions from the
+        Rust community
+      :URL: https://doc.rust-lang.org/book/
+      :Date: Accessed Sep 11 2024
+      :Keywords: rust, book.
+      :Description: From the website: "This book fully embraces the
+        potential of Rust to empower its users. It’s a friendly and
+        approachable text intended to help you level up not just your
+        knowledge of Rust, but also your reach and confidence as a
+        programmer in general. So dive in, get ready to learn—and welcome
+        to the Rust community!".
+
+    * Title: **Rust for the Polyglot Programmer**
+
+      :Author: Ian Jackson
+      :URL: https://www.chiark.greenend.org.uk/~ianmdlvl/rust-polyglot/index.html
+      :Date: December 2022
+      :Keywords: rust, blog, tooling.
+      :Description: From the website: "There are many guides and
+        introductions to Rust. This one is something different: it is
+        intended for the experienced programmer who already knows many
+        other programming languages. I try to be comprehensive enough to be
+        a starting point for any area of Rust, but to avoid going into too
+        much detail except where things are not as you might expect. Also
+        this guide is not entirely free of opinion, including
+        recommendations of libraries (crates), tooling, etc.".
+
+    * Title: **Fasterthanli.me**
+
+      :Author: Amos Wenger
+      :URL: https://fasterthanli.me/
+      :Date: Accessed Sep 11 2024
+      :Keywords: rust, blog, news.
+      :Description: From the website: "I make articles and videos about how
+        computers work. My content is long-form, didactic and exploratory
+        — and often an excuse to teach Rust!".
+
+    * Title: **Comprehensive Rust**
+
+      :Author: Android team at Google
+      :URL: https://google.github.io/comprehensive-rust/
+      :Date: Accessed Sep 13 2024
+      :Keywords: rust, blog.
+      :Description: From the website: "The course covers the full spectrum
+        of Rust, from basic syntax to advanced topics like generics and
+        error handling".
+
+    * Title: **The Embedded Rust Book**
+
+      :Author: Multiple contributors, mostly Jorge Aparicio
+      :URL: https://docs.rust-embedded.org/book/
+      :Date: Accessed Sep 13 2024
+      :Keywords: rust, blog.
+      :Description: From the website: "An introductory book about using
+        the Rust Programming Language on "Bare Metal" embedded systems,
+        such as Microcontrollers".
+
+   * Title: **Experiment: Improving the Rust Book**
+
+      :Author: Cognitive Engineering Lab at Brown University
+      :URL: https://rust-book.cs.brown.edu/
+      :Date: Accessed Sep 22 2024
+      :Keywords: rust, blog.
+      :Description: From the website: "The goal of this experiment is to
+        evaluate and improve the content of the Rust Book to help people
+        learn Rust more effectively.".
+
+   * Title: **New Rustacean** (podcast)
+
+      :Author: Chris Krycho
+      :URL: https://newrustacean.com/
+      :Date: Accessed Sep 22 2024
+      :Keywords: rust, podcast.
+      :Description: From the website: "This is a podcast about learning
+        the programming language Rust—from scratch! Apart from this spiffy
+        landing page, all the site content is built with Rust's own
+        documentation tools.".
+
+   * Title: **Opsem-team** (repository)
+
+      :Author: Operational semantics team
+      :URL: https://github.com/rust-lang/opsem-team/tree/main
+      :Date: Accessed Sep 22 2024
+      :Keywords: rust, repository.
+      :Description: From the README: "The opsem team is the successor of
+        the unsafe-code-guidelines working group and responsible for
+        answering many of the difficult questions about the semantics of
+        unsafe Rust".
+
+    * Title: **You Can't Spell Trust Without Rust**
+
+      :Author: Alexis Beingessner
+      :URL: https://repository.library.carleton.ca/downloads/1j92g820w?locale=en
+      :Date: 2015
+      :Keywords: rust, master, thesis.
+      :Description: This thesis focuses on Rust's ownership system, which
+        ensures memory safety by controlling data manipulation and
+        lifetime, while also highlighting its limitations and comparing it
+        to similar systems in Cyclone and C++.
+
+    * Name: **Linux Plumbers (LPC) 2024 Rust presentations**
+
+      :Title: Rust microconference
+      :URL: https://lpc.events/event/18/sessions/186/#20240918
+      :Title: Rust for Linux
+      :URL: https://lpc.events/event/18/contributions/1912/
+      :Title: Journey of a C kernel engineer starting a Rust driver project
+      :URL: https://lpc.events/event/18/contributions/1911/
+      :Title: Crafting a Linux kernel scheduler that runs in user-space
+        using Rust
+      :URL: https://lpc.events/event/18/contributions/1723/
+      :Title: openHCL: A Linux and Rust based paravisor
+      :URL: https://lpc.events/event/18/contributions/1956/
+      :Keywords: rust, lpc, presentations.
+      :Description: A number of LPC talks related to Rust.
+
+    * Name: **The Rustacean Station Podcast**
+
+      :URL: https://rustacean-station.org/
+      :Keywords: rust, podcasts.
+      :Description: A community project for creating podcast content for
+        the Rust programming language.
+
+-------
+
+This document was originally based on:
+
+ https://www.dit.upm.es/~jmseyas/linux/kernel/hackers-docs.html
+
+and written by Juan-Mariano de Goyeneche