kernel/Documentation/userspace-api/index.rst, branch linux-rolling-stable

docs: add luo documentation

2025-11-27T22:24:39Z

Add the documentation files for the Live Update Orchestrator Link: https://lkml.kernel.org/r/20251125165850.3389713-9-pasha.tatashin@soleen.com Signed-off-by: Pasha Tatashin Reviewed-by: Mike Rapoport (Microsoft) Reviewed-by: Pratyush Yadav Tested-by: David Matlack Cc: Aleksander Lobakin Cc: Alexander Graf Cc: Alice Ryhl Cc: Andriy Shevchenko Cc: anish kumar Cc: Anna Schumaker Cc: Bartosz Golaszewski Cc: Bjorn Helgaas Cc: Borislav Betkov Cc: Chanwoo Choi Cc: Chen Ridong Cc: Chris Li Cc: Christian Brauner Cc: Daniel Wagner Cc: Danilo Krummrich Cc: Dan Williams Cc: David Hildenbrand Cc: David Jeffery Cc: David Rientjes Cc: Greg Kroah-Hartman Cc: Guixin Liu Cc: "H. Peter Anvin" Cc: Hugh Dickins Cc: Ilpo Järvinen Cc: Ingo Molnar Cc: Ira Weiny Cc: Jann Horn Cc: Jason Gunthorpe Cc: Jens Axboe Cc: Joanthan Cameron Cc: Joel Granados Cc: Johannes Weiner Cc: Jonathan Corbet Cc: Lennart Poettering Cc: Leon Romanovsky Cc: Leon Romanovsky Cc: Lukas Wunner Cc: Marc Rutland Cc: Masahiro Yamada Cc: Matthew Maurer Cc: Miguel Ojeda Cc: Myugnjoo Ham Cc: Parav Pandit Cc: Pratyush Yadav Cc: Randy Dunlap Cc: Roman Gushchin Cc: Saeed Mahameed Cc: Samiullah Khawaja Cc: Song Liu Cc: Steven Rostedt Cc: Stuart Hayes Cc: Tejun Heo Cc: Thomas Gleinxer Cc: Thomas Weißschuh Cc: Vincent Guittot Cc: William Tu Cc: Yoann Congal Cc: Zhu Yanjun Cc: Zijun Hu Signed-off-by: Andrew Morton

Merge tag 'for-linus-fwctl' of git://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma

2025-03-29T17:45:20Z

Pull fwctl subsystem from Jason Gunthorpe: "fwctl is a new subsystem intended to bring some common rules and order to the growing pattern of exposing a secure FW interface directly to userspace. Unlike existing places like RDMA/DRM/VFIO/uacce that are exposing a device for datapath operations fwctl is focused on debugging, configuration and provisioning of the device. It will not have the necessary features like interrupt delivery to support a datapath. This concept is similar to the long standing practice in the "HW" RAID space of having a device specific misc device to manage the RAID controller FW. fwctl generalizes this notion of a companion debug and management interface that goes along with a dataplane implemented in an appropriate subsystem. There have been three LWN articles written discussing various aspects of this: https://lwn.net/Articles/955001/ https://lwn.net/Articles/969383/ https://lwn.net/Articles/990802/ This includes three drivers to launch the subsystem: - CXL provides a vendor scheme for executing commands and a way to learn the 'command effects' (ie the security properties) of such commands. The fwctl driver allows access to these mechanism within the fwctl security model - mlx5 is family of networking products, the driver supports all current Mellanox HW still receiving FW feature updates. This includes RDMA multiprotocol NICs like ConnectX and the Bluefield family of Smart NICs. - AMD/Pensando Distributed Services card is a multi protocol Smart NIC with a multi PCI function design. fwctl works on the management PCI function following a 'command effects' model similar to CXL" * tag 'for-linus-fwctl' of git://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma: (30 commits) pds_fwctl: add Documentation entries pds_fwctl: add rpc and query support pds_fwctl: initial driver framework pds_core: add new fwctl auxiliary_device pds_core: specify auxiliary_device to be created pds_core: make pdsc_auxbus_dev_del() void cxl: Fixup kdoc issues for include/cxl/features.h fwctl/cxl: Add documentation to FWCTL CXL cxl/test: Add Set Feature support to cxl_test cxl/test: Add Get Feature support to cxl_test cxl: Add support to handle user feature commands for set feature cxl: Add support to handle user feature commands for get feature cxl: Add support for fwctl RPC command to enable CXL feature commands cxl: Move cxl feature command structs to user header cxl: Add FWCTL support to CXL mlx5: Create an auxiliary device for fwctl_mlx5 fwctl/mlx5: Support for communicating with mlx5 fw fwctl: Add documentation fwctl: FWCTL_RPC to execute a Remote Procedure Call to device firmware taint: Add TAINT_FWCTL ...

Documentation: dma-buf: heaps: Add heap name definitions

2025-03-12T22:49:02Z

Following a recent discussion at last Plumbers, John Stultz, Sumit Sewal, TJ Mercier and I came to an agreement that we should document what the dma-buf heaps names are expected to be, and what the buffers attributes you'll get should be documented. Let's create that doc to make sure those attributes and names are guaranteed going forward. Reviewed-by: T.J. Mercier Signed-off-by: Maxime Ripard Signed-off-by: Jonathan Corbet Link: https://lore.kernel.org/r/20250306135114.1943738-1-mripard@kernel.org

fwctl: Add documentation

2025-03-06T19:13:13Z

Document the purpose and rules for the fwctl subsystem. Link in kdocs to the doc tree. Link: https://patch.msgid.link/r/6-v5-642aa0c94070+4447f-fwctl_jgg@nvidia.com Nacked-by: Jakub Kicinski Link: https://lore.kernel.org/r/20240603114250.5325279c@kernel.org Acked-by: Daniel Vetter Link: https://lore.kernel.org/r/ZrHY2Bds7oF7KRGz@phenom.ffwll.local Reviewed-by: Jonathan Cameron Reviewed-by: Dave Jiang Reviewed-by: Shannon Nelson Reviewed-by: Bagas Sanjaya Signed-off-by: Jason Gunthorpe

Merge tag 'char-misc-6.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc

2025-01-28T00:51:51Z

Pull Char/Misc/IIO driver updates from Greg KH: "Here is the "big" set of char/misc/iio and other smaller driver subsystem updates for 6.14-rc1. Loads of different things in here this development cycle, highlights are: - ntsync "driver" to handle Windows locking types enabling Wine to work much better on many workloads (i.e. games). The driver framework was in 6.13, but now it's enabled and fully working properly. Should make many SteamOS users happy. Even comes with tests! - Large IIO driver updates and bugfixes - FPGA driver updates - Coresight driver updates - MHI driver updates - PPS driver updatesa - const bin_attribute reworking for many drivers - binder driver updates - smaller driver updates and fixes All of these have been in linux-next for a while with no reported issues" * tag 'char-misc-6.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc: (311 commits) ntsync: Fix reference leaks in the remaining create ioctls. spmi: hisi-spmi-controller: Drop duplicated OF node assignment in spmi_controller_probe() spmi: Set fwnode for spmi devices ntsync: fix a file reference leak in drivers/misc/ntsync.c scripts/tags.sh: Don't tag usages of DECLARE_BITMAP dt-bindings: interconnect: qcom,msm8998-bwmon: Add SM8750 CPU BWMONs dt-bindings: interconnect: OSM L3: Document sm8650 OSM L3 compatible dt-bindings: interconnect: qcom-bwmon: Document QCS615 bwmon compatibles interconnect: sm8750: Add missing const to static qcom_icc_desc memstick: core: fix kernel-doc notation intel_th: core: fix kernel-doc warnings binder: log transaction code on failure iio: dac: ad3552r-hs: clear reset status flag iio: dac: ad3552r-common: fix ad3541/2r ranges iio: chemical: bme680: Fix uninitialized variable in __bme680_read_raw() misc: fastrpc: Fix copy buffer page size misc: fastrpc: Fix registered buffer page address misc: fastrpc: Deregister device nodes properly in error scenarios nvmem: core: improve range check for nvmem_cell_write() nvmem: qcom-spmi-sdam: Set size in struct nvmem_config ...

docs: ntsync: Add documentation for the ntsync uAPI.

2025-01-08T12:18:12Z

Add an overall explanation of the driver architecture, and complete and precise specification for its intended behaviour. Signed-off-by: Elizabeth Figura Link: https://lore.kernel.org/r/20241213193511.457338-30-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman

exec: Add a new AT_EXECVE_CHECK flag to execveat(2)

2024-12-19T01:00:29Z

Add a new AT_EXECVE_CHECK flag to execveat(2) to check if a file would be allowed for execution. The main use case is for script interpreters and dynamic linkers to check execution permission according to the kernel's security policy. Another use case is to add context to access logs e.g., which script (instead of interpreter) accessed a file. As any executable code, scripts could also use this check [1]. This is different from faccessat(2) + X_OK which only checks a subset of access rights (i.e. inode permission and mount options for regular files), but not the full context (e.g. all LSM access checks). The main use case for access(2) is for SUID processes to (partially) check access on behalf of their caller. The main use case for execveat(2) + AT_EXECVE_CHECK is to check if a script execution would be allowed, according to all the different restrictions in place. Because the use of AT_EXECVE_CHECK follows the exact kernel semantic as for a real execution, user space gets the same error codes. An interesting point of using execveat(2) instead of openat2(2) is that it decouples the check from the enforcement. Indeed, the security check can be logged (e.g. with audit) without blocking an execution environment not yet ready to enforce a strict security policy. LSMs can control or log execution requests with security_bprm_creds_for_exec(). However, to enforce a consistent and complete access control (e.g. on binary's dependencies) LSMs should restrict file executability, or measure executed files, with security_file_open() by checking file->f_flags & __FMODE_EXEC. Because AT_EXECVE_CHECK is dedicated to user space interpreters, it doesn't make sense for the kernel to parse the checked files, look for interpreters known to the kernel (e.g. ELF, shebang), and return ENOEXEC if the format is unknown. Because of that, security_bprm_check() is never called when AT_EXECVE_CHECK is used. It should be noted that script interpreters cannot directly use execveat(2) (without this new AT_EXECVE_CHECK flag) because this could lead to unexpected behaviors e.g., `python script.sh` could lead to Bash being executed to interpret the script. Unlike the kernel, script interpreters may just interpret the shebang as a simple comment, which should not change for backward compatibility reasons. Because scripts or libraries files might not currently have the executable permission set, or because we might want specific users to be allowed to run arbitrary scripts, the following patch provides a dynamic configuration mechanism with the SECBIT_EXEC_RESTRICT_FILE and SECBIT_EXEC_DENY_INTERACTIVE securebits. This is a redesign of the CLIP OS 4's O_MAYEXEC: https://github.com/clipos-archive/src_platform_clip-patches/blob/f5cb330d6b684752e403b4e41b39f7004d88e561/1901_open_mayexec.patch This patch has been used for more than a decade with customized script interpreters. Some examples can be found here: https://github.com/clipos-archive/clipos4_portage-overlay/search?q=O_MAYEXEC Cc: Al Viro Cc: Christian Brauner Cc: Kees Cook Acked-by: Paul Moore Reviewed-by: Serge Hallyn Reviewed-by: Jeff Xu Tested-by: Jeff Xu Link: https://docs.python.org/3/library/io.html#io.open_code [1] Signed-off-by: Mickaël Salaün Link: https://lore.kernel.org/r/20241212174223.389435-2-mic@digikod.net Signed-off-by: Kees Cook

Merge tag 'iommu-updates-v6.11' of git://git.kernel.org/pub/scm/linux/kernel/git/iommu/linux

2024-07-19T16:59:58Z

Pull iommu updates from Will Deacon: "Core: - Support for the "ats-supported" device-tree property - Removal of the 'ops' field from 'struct iommu_fwspec' - Introduction of iommu_paging_domain_alloc() and partial conversion of existing users - Introduce 'struct iommu_attach_handle' and provide corresponding IOMMU interfaces which will be used by the IOMMUFD subsystem - Remove stale documentation - Add missing MODULE_DESCRIPTION() macro - Misc cleanups Allwinner Sun50i: - Ensure bypass mode is disabled on H616 SoCs - Ensure page-tables are allocated below 4GiB for the 32-bit page-table walker - Add new device-tree compatible strings AMD Vi: - Use try_cmpxchg64() instead of cmpxchg64() when updating pte Arm SMMUv2: - Print much more useful information on context faults - Fix Qualcomm TBU probing when CONFIG_ARM_SMMU_QCOM_DEBUG=n - Add new Qualcomm device-tree bindings Arm SMMUv3: - Support for hardware update of access/dirty bits and reporting via IOMMUFD - More driver rework from Jason, this time updating the PASID/SVA support to prepare for full IOMMUFD support - Add missing MODULE_DESCRIPTION() macro - Minor fixes and cleanups NVIDIA Tegra: - Fix for benign fwspec initialisation issue exposed by rework on the core branch Intel VT-d: - Use try_cmpxchg64() instead of cmpxchg64() when updating pte - Use READ_ONCE() to read volatile descriptor status - Remove support for handling Execute-Requested requests - Avoid calling iommu_domain_alloc() - Minor fixes and refactoring Qualcomm MSM: - Updates to the device-tree bindings" * tag 'iommu-updates-v6.11' of git://git.kernel.org/pub/scm/linux/kernel/git/iommu/linux: (72 commits) iommu/tegra-smmu: Pass correct fwnode to iommu_fwspec_init() iommu/vt-d: Fix identity map bounds in si_domain_init() iommu: Move IOMMU_DIRTY_NO_CLEAR define dt-bindings: iommu: Convert msm,iommu-v0 to yaml iommu/vt-d: Fix aligned pages in calculate_psi_aligned_address() iommu/vt-d: Limit max address mask to MAX_AGAW_PFN_WIDTH docs: iommu: Remove outdated Documentation/userspace-api/iommu.rst arm64: dts: fvp: Enable PCIe ATS for Base RevC FVP iommu/of: Support ats-supported device-tree property dt-bindings: PCI: generic: Add ats-supported property iommu: Remove iommu_fwspec ops OF: Simplify of_iommu_configure() ACPI: Retire acpi_iommu_fwspec_ops() iommu: Resolve fwspec ops automatically iommu/mediatek-v1: Clean up redundant fwspec checks RDMA/usnic: Use iommu_paging_domain_alloc() wifi: ath11k: Use iommu_paging_domain_alloc() wifi: ath10k: Use iommu_paging_domain_alloc() drm/msm: Use iommu_paging_domain_alloc() vhost-vdpa: Use iommu_paging_domain_alloc() ...

docs: iommu: Remove outdated Documentation/userspace-api/iommu.rst

2024-07-09T10:08:17Z

The Documentation/userspace-api/iommu.rst file has become outdated due to the removal of associated structures and APIs. Specifically, struct such as iommu_cache_invalidate_info and guest pasid related uapi were removed in commit 0c9f17877891 ("iommu: Remove guest pasid related interfaces and definitions"). And the corresponding uapi/linux/iommu.h file was removed in commit 00a9bc607043 ("iommu: Move iommu fault data to linux/iommu.h"). Signed-off-by: Mark-PK Tsai Reviewed-by: Lu Baolu Link: https://lore.kernel.org/r/20240702120617.26882-1-mark-pk.tsai@mediatek.com [will: Remove stale reference to 'iommu' from index.rst] Signed-off-by: Will Deacon

mm/memfd: add documentation for MFD_NOEXEC_SEAL MFD_EXEC

2024-06-15T17:43:07Z

When MFD_NOEXEC_SEAL was introduced, there was one big mistake: it didn't have proper documentation. This led to a lot of confusion, especially about whether or not memfd created with the MFD_NOEXEC_SEAL flag is sealable. Before MFD_NOEXEC_SEAL, memfd had to explicitly set MFD_ALLOW_SEALING to be sealable, so it's a fair question. As one might have noticed, unlike other flags in memfd_create, MFD_NOEXEC_SEAL is actually a combination of multiple flags. The idea is to make it easier to use memfd in the most common way, which is NOEXEC + F_SEAL_EXEC + MFD_ALLOW_SEALING. This works with sysctl vm.noexec to help existing applications move to a more secure way of using memfd. Proposals have been made to put MFD_NOEXEC_SEAL non-sealable, unless MFD_ALLOW_SEALING is set, to be consistent with other flags [1], Those are based on the viewpoint that each flag is an atomic unit, which is a reasonable assumption. However, MFD_NOEXEC_SEAL was designed with the intent of promoting the most secure method of using memfd, therefore a combination of multiple functionalities into one bit. Furthermore, the MFD_NOEXEC_SEAL has been added for more than one year, and multiple applications and distributions have backported and utilized it. Altering ABI now presents a degree of risk and may lead to disruption. MFD_NOEXEC_SEAL is a new flag, and applications must change their code to use it. There is no backward compatibility problem. When sysctl vm.noexec == 1 or 2, applications that don't set MFD_NOEXEC_SEAL or MFD_EXEC will get MFD_NOEXEC_SEAL memfd. And old-application might break, that is by-design, in such a system vm.noexec = 0 shall be used. Also no backward compatibility problem. I propose to include this documentation patch to assist in clarifying the semantics of MFD_NOEXEC_SEAL, thereby preventing any potential future confusion. Finally, I would like to express my gratitude to David Rheinsberg and Barnabás Pőcze for initiating the discussion on the topic of sealability. [1] https://lore.kernel.org/lkml/20230714114753.170814-1-david@readahead.eu/ [jeffxu@chromium.org: updates per Randy] Link: https://lkml.kernel.org/r/20240611034903.3456796-2-jeffxu@chromium.org [jeffxu@chromium.org: v3] Link: https://lkml.kernel.org/r/20240611231409.3899809-2-jeffxu@chromium.org Link: https://lkml.kernel.org/r/20240607203543.2151433-2-jeffxu@google.com Signed-off-by: Jeff Xu Reviewed-by: Randy Dunlap Cc: Aleksa Sarai Cc: Barnabás Pőcze Cc: Daniel Verkamp Cc: David Rheinsberg Cc: Dmitry Torokhov Cc: Hugh Dickins Cc: Jorge Lucangeli Obes Cc: Kees Cook Cc: Shuah Khan Signed-off-by: Andrew Morton