From 034dd340b08be1f2f0477ad16131d609f9dbd53c Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sun, 30 Aug 2026 09:22:00 -0700 Subject: Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace Pull tracing fixes from Steven Rostedt: - Fix error output of boot instance creation failure Currently if a boot instance creation fails, instead of printing out the name of the instance that failed, it prints "(null)". That is because it prints "cur_str" that had already been processed by strsep(). Print the saved name instead. While at it, print the error code of the failure. - Fix use-after-free for same named historgrams Histograms can be named so that they can be used in multiple events. But if the named histogram has a variable attached, the second event that uses the named histogram which duplicates it and needs to free the original after duplication leaves the old variable in place and still visible. If another histogram uses than variable, it will use the stale one which will try to reference the freed duplicate histogram and crash the kernel. Free the duplicate variables along with the duplicated histogram data. - Check return value of kthread_run() in event self test The events self tests uses a kthread for testing but does not check if it succeeded in creating a kthread. If the kthread creation were to fail, the code will still try to call kthread_stop() on the error returned. - Fix race between reading trace_pipe and updating subbuffer size If a user is reading the trace_pipe file at the same time they update the ring buffer sub-buffer size, can cause the trace_pipe read to read stale data. Add trace_access_lock() around updating the ring buffer sub-buffer size. - Fix eventfs_inode on failure path in creation of the events directory In the creation of the "events" directory, if after allocating the eventfs_inode a failure is detected, it calls cleanup_ei() which calls free_ei(). The free_ei() will test if eventfs_inode being freed has no children. It is a bug if it does. But on the failure case of the creation of the "events" directory, the children lists have not yet been initialized and the free will trigger a warning because list_empty() on an uninitialized list returns false. Move the initialization into init_ei() where it makes more sense and makes sure that a created eventfs_inode has its lists initialized upon creation. - Check return value of kthread_run() in ftrace direct sample code The sample code that shows how to use the ftrace direct calls does not test the return of kthread_run() to see if it succeeds. Return a failure if the kthread_run() doesn't succeed. - Clear user events state on fork in case of alloc failure On fork, the child gets a pointer to the parent's user events state. It makes a copy of it then updates the child's pointer to it. But if the allocation fails, the duplication function leaves the child with a pointer to its parent's descriptor. When the child cleans up its data, it will free the parent's descriptor while the parent is still using it. In the duplication function, set the child's user_event_mm to NULL before testing if the allocation succeeded, and when it exits it will not free the parent's descriptor. - Fix retry exhaustion in simple ring buffer reader swap simple_ring_buffer_swap_reader_page() starts with retry set to 8 and post-decrements it only after a failed link replacement. On the final attempt, a successful replacement leaves retry at zero, while a failed replacement leaves it at -1. But the check for success expects the retry value to be non-zero and exits with an error on zero. This is the opposite result. Fix it. - Fail nicely when the remote swap_reader_page() returns an error Currently, if the swap_reader_page() of a remote buffer fails, it triggers a WARN_ON_ONCE() and continues normally. Instead, have it exit with an error and a pr_warn() print instead of a full WARNING. * tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: ring-buffer: Stop remote reader update when page swap fails tracing: Fix retry exhaustion in simple ring buffer reader swap tracing/user_events: Clear copied tracing state before fork duplication samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify eventfs: Initialize ei->children and ei->list in init_ei() tracing: Fix use-after-free in trace_pipe read on sub-buffer order change tracing: Fix crash passing ERR_PTR to kthread_stop() tracing: Fix use-after-free with same-name named triggers tracing: Fix logged instance name on creation failure --- Documentation/arch/arc/arc.rst | 85 +++++++++++++++++++++++++++++++++++++ Documentation/arch/arc/features.rst | 3 ++ Documentation/arch/arc/index.rst | 10 +++++ 3 files changed, 98 insertions(+) create mode 100644 Documentation/arch/arc/arc.rst create mode 100644 Documentation/arch/arc/features.rst create mode 100644 Documentation/arch/arc/index.rst (limited to 'Documentation/arch/arc') diff --git a/Documentation/arch/arc/arc.rst b/Documentation/arch/arc/arc.rst new file mode 100644 index 000000000..5923dee37 --- /dev/null +++ b/Documentation/arch/arc/arc.rst @@ -0,0 +1,85 @@ +.. SPDX-License-Identifier: GPL-2.0 + +Linux kernel for ARC processors +******************************* + +Other sources of information +############################ + +Below are some resources where more information can be found on +ARC processors and relevant open source projects. + +- ``_ - Community portal for open source on ARC. + Good place to start to find relevant FOSS projects, toolchain releases, + news items and more. + +- ``_ - + Home for all development activities regarding open source projects for + ARC processors. Some of the projects are forks of various upstream projects, + where "work in progress" is hosted prior to submission to upstream projects. + Other projects are developed by Synopsys and made available to community + as open source for use on ARC Processors. + +- `Official Synopsys ARC Processors website + `_ - + location, with access to some IP documentation (`Programmer's Reference + Manual, AKA PRM for ARC HS processors + `_) + and free versions of some commercial tools (`Free nSIM + `_ and + `MetaWare Light Edition `_). + Please note though, registration is required to access both the documentation and + the tools. + +Important note on ARC processors configurability +################################################ + +ARC processors are highly configurable and several configurable options +are supported in Linux. Some options are transparent to software +(e.g., cache geometries), some can be detected at runtime and configured +and used accordingly, while some need to be explicitly selected or configured +in the kernel's configuration utility (AKA "make menuconfig"). + +However not all configurable options are supported when an ARC processor +is to run Linux. SoC design teams should refer to "Appendix E: +Configuration for ARC Linux" in the ARC HS Databook for configurability +guidelines. + +Following these guidelines and selecting valid configuration options +up front is critical to help prevent any unwanted issues during +SoC bringup and software development in general. + +Building the Linux kernel for ARC processors +############################################ + +The process of kernel building for ARC processors is the same as for any other +architecture and could be done in 2 ways: + +- Cross-compilation: process of compiling for ARC targets on a development + host with a different processor architecture (generally x86_64/amd64). +- Native compilation: process of compiling for ARC on a ARC platform + (hardware board or a simulator like QEMU) with complete development environment + (GNU toolchain, dtc, make etc) installed on the platform. + +In both cases, up-to-date GNU toolchain for ARC for the host is needed. +Synopsys offers prebuilt toolchain releases which can be used for this purpose, +available from: + +- Synopsys GNU toolchain releases: + ``_ + +- Linux kernel compilers collection: + ``_ + +- Bootlin's toolchain collection: ``_ + +Once the toolchain is installed in the system, make sure its "bin" folder +is added in your ``PATH`` environment variable. Then set ``ARCH=arc`` & +``CROSS_COMPILE=arc-linux`` (or whatever matches installed ARC toolchain prefix) +and then as usual ``make defconfig && make``. + +This will produce "vmlinux" file in the root of the kernel source tree +usable for loading on the target system via JTAG. +If you need to get an image usable with U-Boot bootloader, +type ``make uImage`` and ``uImage`` will be produced in ``arch/arc/boot`` +folder. diff --git a/Documentation/arch/arc/features.rst b/Documentation/arch/arc/features.rst new file mode 100644 index 000000000..49ff446ff --- /dev/null +++ b/Documentation/arch/arc/features.rst @@ -0,0 +1,3 @@ +.. SPDX-License-Identifier: GPL-2.0 + +.. kernel-feat:: features arc diff --git a/Documentation/arch/arc/index.rst b/Documentation/arch/arc/index.rst new file mode 100644 index 000000000..10bf8c270 --- /dev/null +++ b/Documentation/arch/arc/index.rst @@ -0,0 +1,10 @@ +=================== +ARC architecture +=================== + +.. toctree:: + :maxdepth: 1 + + arc + + features -- cgit v1.3.1