From 22098763a10d9c1340827fcf6edab66f153b27f0 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sun, 13 Sep 2026 12:27:00 -0700 Subject: Merge tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace 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 ... --- Documentation/process/changes.rst | 570 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 570 insertions(+) create mode 100644 Documentation/process/changes.rst (limited to 'Documentation/process/changes.rst') diff --git a/Documentation/process/changes.rst b/Documentation/process/changes.rst new file mode 100644 index 000000000..0aa232b11 --- /dev/null +++ b/Documentation/process/changes.rst @@ -0,0 +1,570 @@ +.. _changes: + +Minimal requirements to compile the Kernel +++++++++++++++++++++++++++++++++++++++++++ + +Intro +===== + +This document is designed to provide a list of the minimum levels of +software necessary to run the current kernel version. + +This document is originally based on my "Changes" file for 2.0.x kernels +and therefore owes credit to the same people as that file (Jared Mauch, +Axel Boldt, Alessandro Sigala, and countless other users all over the +'net). + +Current Minimal Requirements +**************************** + +Upgrade to at **least** these software revisions before thinking you've +encountered a bug! If you're unsure what version you're currently +running, the suggested command should tell you. For a list of the programs +on your system including their version execute ./scripts/ver_linux + +Again, keep in mind that this list assumes you are already functionally +running a Linux kernel. Also, not all tools are necessary on all +systems; obviously, if you don't have any PC Card hardware, for example, +you probably do not need to concern yourself with pcmciautils. + +====================== =============== ======================================== + Program Minimal version Command to check the version +====================== =============== ======================================== +bash 4.2 bash --version +bc 1.06.95 bc --version +bindgen (optional) 0.71.1 bindgen --version +binutils 2.30 ld -v +bison 2.0 bison --version +btrfs-progs 0.18 btrfs --version +Clang/LLVM (optional) 17.0.1 clang --version +e2fsprogs 1.41.4 e2fsck -V +flex 2.5.35 flex --version +gdb 7.2 gdb --version +GNU awk (optional) 5.1.0 gawk --version +GNU C 8.1 gcc --version +GNU make 4.0 make --version +GNU tar 1.28 tar --version +GRUB 0.93 grub --version || grub-install --version +gtags (optional) 6.6.5 gtags --version +iptables 1.4.2 iptables -V +jfsutils 1.1.3 fsck.jfs -V +kmod 13 kmod -V +mcelog 0.6 mcelog --version +mkimage (optional) 2017.01 mkimage --version +nfs-utils 1.0.5 showmount --version +openssl & libcrypto 1.0.0 openssl version +pahole 1.26 pahole --version +pcmciautils 004 pccardctl -V +PPP 2.4.0 pppd --version +procps 3.2.0 ps --version +Python 3.9.x python3 --version +quota-tools 3.09 quota -V +Rust (optional) 1.85.0 rustc --version +Sphinx\ [#f1]_ 3.4.3 sphinx-build --version +squashfs-tools 4.0 mksquashfs -version +udev 081 udevadm --version +util-linux 2.10o mount --version +xfsprogs 2.6.0 xfs_db -V +====================== =============== ======================================== + +.. [#f1] Sphinx is needed only to build the Kernel documentation + +Kernel compilation +****************** + +GCC +--- + +The gcc version requirements may vary depending on the type of CPU in your +computer. + +Clang/LLVM (optional) +--------------------- + +The latest formal release of clang and LLVM utils (according to +`releases.llvm.org `_) are supported for building +kernels. Older releases aren't guaranteed to work, and we may drop workarounds +from the kernel that were used to support older versions. Please see additional +docs on :ref:`Building Linux with Clang/LLVM `. + +Rust (optional) +--------------- + +A recent version of the Rust compiler is required. + +Please see Documentation/rust/quick-start.rst for instructions on how to +satisfy the build requirements of Rust support. In particular, the ``Makefile`` +target ``rustavailable`` is useful to check why the Rust toolchain may not +be detected. + +bindgen (optional) +------------------ + +``bindgen`` is used to generate the Rust bindings to the C side of the kernel. +It depends on ``libclang``. + +Make +---- + +You will need GNU make 4.0 or later to build the kernel. + +Bash +---- + +Some bash scripts are used for the kernel build. +Bash 4.2 or newer is needed. + +Binutils +-------- + +Binutils 2.30 or newer is needed to build the kernel. + +pkg-config +---------- + +The build system, as of 4.18, requires pkg-config to check for installed +kconfig tools and to determine flags settings for use in +'make {g,x}config'. Previously pkg-config was being used but not +verified or documented. + +Flex +---- + +Since Linux 4.16, the build system generates lexical analyzers +during build. This requires flex 2.5.35 or later. + + +Bison +----- + +Since Linux 4.16, the build system generates parsers +during build. This requires bison 2.0 or later. + +pahole +------ + +Since Linux 5.2, if CONFIG_DEBUG_INFO_BTF is selected, the build system +generates BTF (BPF Type Format) from DWARF in vmlinux, a bit later from kernel +modules as well. This requires pahole v1.22 or later. + +It is found in the 'dwarves' or 'pahole' distro packages or from +https://fedorapeople.org/~acme/dwarves/. + +Perl +---- + +You will need perl 5 and the following modules: ``Getopt::Long``, +``Getopt::Std``, ``File::Basename``, and ``File::Find`` to build the kernel. + +Python +------ + +Several config options require it: it is required for arm/arm64 +default configs, CONFIG_LTO_CLANG, some DRM optional configs, +the kernel-doc tool, and docs build (Sphinx), among others. + +BC +-- + +You will need bc to build kernels 3.10 and higher + + +OpenSSL +------- + +Module signing and external certificate handling use the OpenSSL program and +crypto library to do key creation and signature generation. + +You will need openssl to build kernels 3.7 and higher if module signing is +enabled. You will also need openssl development packages to build kernels 4.3 +and higher. + +Tar +--- + +GNU tar is needed if you want to enable access to the kernel headers via sysfs +(CONFIG_IKHEADERS). + +gtags / GNU GLOBAL (optional) +----------------------------- + +The kernel build requires GNU GLOBAL version 6.6.5 or later to generate +tag files through ``make gtags``. This is due to its use of the gtags +``-C (--directory)`` flag. + +mkimage +------- + +This tool is used when building a Flat Image Tree (FIT), commonly used on ARM +platforms. The tool is available via the ``u-boot-tools`` package or can be +built from the U-Boot source code. See the instructions at +https://docs.u-boot.org/en/latest/build/tools.html#building-tools-for-linux + +GNU AWK +------- + +GNU AWK is needed if you want kernel builds to generate address range data for +builtin modules (CONFIG_BUILTIN_MODULE_RANGES). + +System utilities +**************** + +Architectural changes +--------------------- + +DevFS has been obsoleted in favour of udev +(https://www.kernel.org/pub/linux/utils/kernel/hotplug/) + +32-bit UID support is now in place. Have fun! + +Linux documentation for functions is transitioning to inline +documentation via specially-formatted comments near their +definitions in the source. These comments can be combined with ReST +files in the Documentation/ directory to make enriched documentation, which can +then be converted to PostScript, HTML, LaTex, ePUB and PDF files. +In order to convert from ReST format to a format of your choice, you'll need +Sphinx. + +Util-linux +---------- + +New versions of util-linux provide ``fdisk`` support for larger disks, +support new options to mount, recognize more supported partition +types, and similar goodies. +You'll probably want to upgrade. + +Ksymoops +-------- + +If the unthinkable happens and your kernel oopses, you may need the +ksymoops tool to decode it, but in most cases you don't. +It is generally preferred to build the kernel with ``CONFIG_KALLSYMS`` so +that it produces readable dumps that can be used as-is (this also +produces better output than ksymoops). If for some reason your kernel +is not build with ``CONFIG_KALLSYMS`` and you have no way to rebuild and +reproduce the Oops with that option, then you can still decode that Oops +with ksymoops. + +Mkinitrd +-------- + +These changes to the ``/lib/modules`` file tree layout also require that +mkinitrd be upgraded. + +E2fsprogs +--------- + +The latest version of ``e2fsprogs`` fixes several bugs in fsck and +debugfs. Obviously, it's a good idea to upgrade. + +JFSutils +-------- + +The ``jfsutils`` package contains the utilities for the file system. +The following utilities are available: + +- ``fsck.jfs`` - initiate replay of the transaction log, and check + and repair a JFS formatted partition. + +- ``mkfs.jfs`` - create a JFS formatted partition. + +- other file system utilities are also available in this package. + +Xfsprogs +-------- + +The latest version of ``xfsprogs`` contains ``mkfs.xfs``, ``xfs_db``, and the +``xfs_repair`` utilities, among others, for the XFS filesystem. It is +architecture independent and any version from 2.0.0 onward should +work correctly with this version of the XFS kernel code (2.6.0 or +later is recommended, due to some significant improvements). + +PCMCIAutils +----------- + +PCMCIAutils replaces ``pcmcia-cs``. It properly sets up +PCMCIA sockets at system startup and loads the appropriate modules +for 16-bit PCMCIA devices if the kernel is modularized and the hotplug +subsystem is used. + +Quota-tools +----------- + +Support for 32 bit uid's and gid's is required if you want to use +the newer version 2 quota format. Quota-tools version 3.07 and +newer has this support. Use the recommended version or newer +from the table above. + +Intel IA32 microcode +-------------------- + +A driver has been added to allow updating of Intel IA32 microcode, +accessible as a normal (misc) character device. If you are not using +udev you may need to:: + + mkdir /dev/cpu + mknod /dev/cpu/microcode c 10 184 + chmod 0644 /dev/cpu/microcode + +as root before you can use this. You'll probably also want to +get the user-space microcode_ctl utility to use with this. + +udev +---- + +``udev`` is a userspace application for populating ``/dev`` dynamically with +only entries for devices actually present. ``udev`` replaces the basic +functionality of devfs, while allowing persistent device naming for +devices. + +FUSE +---- + +Needs libfuse 2.4.0 or later. Absolute minimum is 2.3.0 but mount +options ``direct_io`` and ``kernel_cache`` won't work. + +Networking +********** + +General changes +--------------- + +If you have advanced network configuration needs, you should probably +consider using the network tools from ip-route2. + +Packet Filter / NAT +------------------- +The packet filtering and NAT code uses the same tools like the previous 2.4.x +kernel series (iptables). It still includes backwards-compatibility modules +for 2.2.x-style ipchains and 2.0.x-style ipfwadm. + +PPP +--- + +The PPP driver has been restructured to support multilink and to +enable it to operate over diverse media layers. If you use PPP, +upgrade pppd to at least 2.4.0. + +If you are not using udev, you must have the device file /dev/ppp +which can be made by:: + + mknod /dev/ppp c 108 0 + +as root. + +NFS-utils +--------- + +In ancient (2.4 and earlier) kernels, the nfs server needed to know +about any client that expected to be able to access files via NFS. This +information would be given to the kernel by ``mountd`` when the client +mounted the filesystem, or by ``exportfs`` at system startup. exportfs +would take information about active clients from ``/var/lib/nfs/rmtab``. + +This approach is quite fragile as it depends on rmtab being correct +which is not always easy, particularly when trying to implement +fail-over. Even when the system is working well, ``rmtab`` suffers from +getting lots of old entries that never get removed. + +With modern kernels we have the option of having the kernel tell mountd +when it gets a request from an unknown host, and mountd can give +appropriate export information to the kernel. This removes the +dependency on ``rmtab`` and means that the kernel only needs to know about +currently active clients. + +To enable this new functionality, you need to:: + + mount -t nfsd nfsd /proc/fs/nfsd + +before running exportfs or mountd. It is recommended that all NFS +services be protected from the internet-at-large by a firewall where +that is possible. + +mcelog +------ + +On x86 kernels the mcelog utility is needed to process and log machine check +events when ``CONFIG_X86_MCE`` is enabled. Machine check events are errors +reported by the CPU. Processing them is strongly encouraged. + +Kernel documentation +******************** + +Sphinx +------ + +Please see :ref:`sphinx_install` in Documentation/doc-guide/sphinx.rst +for details about Sphinx requirements. + +rustdoc +------- + +``rustdoc`` is used to generate the documentation for Rust code. Please see +Documentation/rust/general-information.rst for more information. + +Getting updated software +======================== + +Kernel compilation +****************** + +gcc +--- + +- + +Clang/LLVM +---------- + +- :ref:`Getting LLVM `. + +Rust +---- + +- Documentation/rust/quick-start.rst. + +bindgen +------- + +- Documentation/rust/quick-start.rst. + +Make +---- + +- + +Bash +---- + +- + +Binutils +-------- + +- + +Flex +---- + +- + +Bison +----- + +- + +OpenSSL +------- + +- + +System utilities +**************** + +Util-linux +---------- + +- + +Kmod +---- + +- +- + +Ksymoops +-------- + +- + +Mkinitrd +-------- + +- + +E2fsprogs +--------- + +- +- + +JFSutils +-------- + +- + +Xfsprogs +-------- + +- +- + +Pcmciautils +----------- + +- + +Quota-tools +----------- + +- + + +Intel P6 microcode +------------------ + +- + +udev +---- + +- + +FUSE +---- + +- + +mcelog +------ + +- + +Networking +********** + +PPP +--- + +- +- +- + +NFS-utils +--------- + +- +- + +Iptables +-------- + +- + +Ip-route2 +--------- + +- + +OProfile +-------- + +- + +Kernel documentation +******************** + +Sphinx +------ + +- -- cgit v1.3.1