Merge branch 'Improve BPF syscall command documentation'

Joe Stringer says:

====================

The state of bpf(2) manual pages today is not exactly ideal. For the
most part, it was written several years ago and has not kept up with the
pace of development in the kernel tree. For instance, out of a total of
~35 commands to the BPF syscall available today, when I pull the
kernel-man-pages tree today I find just 6 documented commands: The very
basics of map interaction and program load.

In contrast, looking at bpf-helpers(7), I am able today to run one
command[0] to fetch API documentation of the very latest eBPF helpers
that have been added to the kernel. This documentation is up to date
because kernel maintainers enforce documenting the APIs as part of
the feature submission process. As far as I can tell, we rely on manual
synchronization from the kernel tree to the kernel-man-pages tree to
distribute these more widely, so all locations may not be completely up
to date. That said, the documentation does in fact exist in the first
place which is a major initial hurdle to overcome.

Given the relative success of the process around bpf-helpers(7) to
encourage developers to document their user-facing changes, in this
patch series I explore applying this technique to bpf(2) as well.
Unfortunately, even with bpf(2) being so out-of-date, there is still a
lot of content to convert over. In particular, the following aspects of
the bpf syscall could also be individually be generated from separate
documentation in the header:
* BPF syscall commands
* BPF map types
* BPF program types
* BPF program subtypes (aka expected_attach_type)
* BPF attachment points

Rather than tackle everything at once, I have focused in this series on
the syscall commands, "enum bpf_cmd". This series is structured to first
import what useful descriptions there are from the kernel-man-pages
tree, then piece-by-piece document a few of the syscalls in more detail
in cases where I could find useful documentation from the git tree or
from a casual read of the code. Not all documentation is comprehensive
at this point, but a basis is provided with examples that can be further
enhanced with subsequent follow-up patches. Note, the series in its
current state only includes documentation around the syscall commands
themselves, so in the short term it doesn't allow us to automate bpf(2)
generation; Only one section of the man page could be replaced. Though
if there is appetite for this approach, this should be trivial to
improve on, even if just by importing the remaining static text from the
kernel-man-pages tree.

Following that, the series enhances the python scripting around parsing
the descriptions from the header files and generating dedicated
ReStructured Text and troff output. Finally, to expose the new text and
reduce the likelihood of having it get out of date or break the docs
parser, it is added to the selftests and exposed through the kernel
documentation web pages.

The eventual goal of this effort would be to extend the kernel UAPI
headers such that each of the categories I had listed above (commands,
maps, progs, hooks) have dedicated documentation in the kernel tree, and
that developers must update the comments in the headers to document the
APIs prior to patch acceptance, and that we could auto-generate the
latest version of the bpf(2) manual pages based on a few static
description sections combined with the dynamically-generated output from
the header.

This patch series can also be found at the following location on GitHub:
https://github.com/joestringer/linux/tree/submit/bpf-command-docs_v2

Thanks also to Quentin Monnet for initial review.

[0]: make -C tools/testing/selftests/bpf docs

v2:
* Remove build infrastructure in favor of kernel-doc directives
* Shift userspace-api docs under Documentation/userspace-api/ebpf
* Fix scripts/bpf_doc.py syscall --header (throw unsupported error)
* Improve .gitignore handling of newly autogenerated files

====================
Acked-by: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

Documentation/bpf/index.rst

@@ -12,9 +12,6 @@ BPF instruction-set.
 The Cilium project also maintains a `BPF and XDP Reference Guide`_
 that goes into great technical depth about the BPF Architecture.
 
-The primary info for the bpf syscall is available in the `man-pages`_
-for `bpf(2)`_.
-
 BPF Type Format (BTF)
 =====================
 
@@ -35,6 +32,12 @@ Two sets of Questions and Answers (Q&A) are maintained.
    bpf_design_QA
    bpf_devel_QA
 
+Syscall API
+===========
+
+The primary info for the bpf syscall is available in the `man-pages`_
+for `bpf(2)`_. For more information about the userspace API, see
+Documentation/userspace-api/ebpf/index.rst.
 
 Helper functions
 ================

Documentation/userspace-api/ebpf/index.rst

+.. SPDX-License-Identifier: GPL-2.0
+
+eBPF Userspace API
+==================
+
+eBPF is a kernel mechanism to provide a sandboxed runtime environment in the
+Linux kernel for runtime extension and instrumentation without changing kernel
+source code or loading kernel modules. eBPF programs can be attached to various
+kernel subsystems, including networking, tracing and Linux security modules
+(LSM).
+
+For internal kernel documentation on eBPF, see Documentation/bpf/index.rst.
+
+.. toctree::
+   :maxdepth: 1
+
+   syscall

Documentation/userspace-api/ebpf/syscall.rst

+.. SPDX-License-Identifier: GPL-2.0
+
+eBPF Syscall
+------------
+
+:Authors: - Alexei Starovoitov <ast@kernel.org>
+          - Joe Stringer <joe@wand.net.nz>
+          - Michael Kerrisk <mtk.manpages@gmail.com>
+
+The primary info for the bpf syscall is available in the `man-pages`_
+for `bpf(2)`_.
+
+bpf() subcommand reference
+~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. kernel-doc:: include/uapi/linux/bpf.h
+   :doc: eBPF Syscall Preamble
+
+.. kernel-doc:: include/uapi/linux/bpf.h
+   :doc: eBPF Syscall Commands
+
+.. Links:
+.. _man-pages: https://www.kernel.org/doc/man-pages/
+.. _bpf(2): https://man7.org/linux/man-pages/man2/bpf.2.html

Documentation/userspace-api/index.rst

@@ -21,6 +21,7 @@ place where this information is gathered.
    unshare
    spec_ctrl
    accelerators/ocxl
+   ebpf/index
    ioctl/index
    iommu
    media/index

MAINTAINERS

@@ -3209,6 +3209,7 @@ T:	git git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git
 F:	Documentation/bpf/
 F:	Documentation/networking/filter.rst
+F:	Documentation/userspace-api/ebpf/
 F:	arch/*/net/*
 F:	include/linux/bpf*
 F:	include/linux/filter.h
@@ -3223,6 +3224,7 @@ F:	net/core/filter.c
 F:	net/sched/act_bpf.c
 F:	net/sched/cls_bpf.c
 F:	samples/bpf/
+F:	scripts/bpf_doc.py
 F:	tools/bpf/
 F:	tools/lib/bpf/
 F:	tools/testing/selftests/bpf/

include/uapi/linux/bpf.h

@@ -93,7 +93,717 @@ union bpf_iter_link_info {
 	} map;
 };
 
-/* BPF syscall commands, see bpf(2) man-page for details. */
+/* BPF syscall commands, see bpf(2) man-page for more details. */
+/**
+ * DOC: eBPF Syscall Preamble
+ *
+ * The operation to be performed by the **bpf**\ () system call is determined
+ * by the *cmd* argument. Each operation takes an accompanying argument,
+ * provided via *attr*, which is a pointer to a union of type *bpf_attr* (see
+ * below). The size argument is the size of the union pointed to by *attr*.
+ */
+/**
+ * DOC: eBPF Syscall Commands
+ *
+ * BPF_MAP_CREATE
+ *	Description
+ *		Create a map and return a file descriptor that refers to the
+ *		map. The close-on-exec file descriptor flag (see **fcntl**\ (2))
+ *		is automatically enabled for the new file descriptor.
+ *
+ *		Applying **close**\ (2) to the file descriptor returned by
+ *		**BPF_MAP_CREATE** will delete the map (but see NOTES).
+ *
+ *	Return
+ *		A new file descriptor (a nonnegative integer), or -1 if an
+ *		error occurred (in which case, *errno* is set appropriately).
+ *
+ * BPF_MAP_LOOKUP_ELEM
+ *	Description
+ *		Look up an element with a given *key* in the map referred to
+ *		by the file descriptor *map_fd*.
+ *
+ *		The *flags* argument may be specified as one of the
+ *		following:
+ *
+ *		**BPF_F_LOCK**
+ *			Look up the value of a spin-locked map without
+ *			returning the lock. This must be specified if the
+ *			elements contain a spinlock.
+ *
+ *	Return
+ *		Returns zero on success. On error, -1 is returned and *errno*
+ *		is set appropriately.
+ *
+ * BPF_MAP_UPDATE_ELEM
+ *	Description
+ *		Create or update an element (key/value pair) in a specified map.
+ *
+ *		The *flags* argument should be specified as one of the
+ *		following:
+ *
+ *		**BPF_ANY**
+ *			Create a new element or update an existing element.
+ *		**BPF_NOEXIST**
+ *			Create a new element only if it did not exist.
+ *		**BPF_EXIST**
+ *			Update an existing element.
+ *		**BPF_F_LOCK**
+ *			Update a spin_lock-ed map element.
+ *
+ *	Return
+ *		Returns zero on success. On error, -1 is returned and *errno*
+ *		is set appropriately.
+ *
+ *		May set *errno* to **EINVAL**, **EPERM**, **ENOMEM**,
+ *		**E2BIG**, **EEXIST**, or **ENOENT**.
+ *
+ *		**E2BIG**
+ *			The number of elements in the map reached the
+ *			*max_entries* limit specified at map creation time.
+ *		**EEXIST**
+ *			If *flags* specifies **BPF_NOEXIST** and the element
+ *			with *key* already exists in the map.
+ *		**ENOENT**
+ *			If *flags* specifies **BPF_EXIST** and the element with
+ *			*key* does not exist in the map.
+ *
+ * BPF_MAP_DELETE_ELEM
+ *	Description
+ *		Look up and delete an element by key in a specified map.
+ *
+ *	Return
+ *		Returns zero on success. On error, -1 is returned and *errno*
+ *		is set appropriately.
+ *
+ * BPF_MAP_GET_NEXT_KEY
+ *	Description
+ *		Look up an element by key in a specified map and return the key
+ *		of the next element. Can be used to iterate over all elements
+ *		in the map.
+ *
+ *	Return
+ *		Returns zero on success. On error, -1 is returned and *errno*
+ *		is set appropriately.
+ *
+ *		The following cases can be used to iterate over all elements of
+ *		the map:
+ *
+ *		* If *key* is not found, the operation returns zero and sets
+ *		  the *next_key* pointer to the key of the first element.
+ *		* If *key* is found, the operation returns zero and sets the
+ *		  *next_key* pointer to the key of the next element.
+ *		* If *key* is the last element, returns -1 and *errno* is set
+ *		  to **ENOENT**.
+ *
+ *		May set *errno* to **ENOMEM**, **EFAULT**, **EPERM**, or
+ *		**EINVAL** on error.
+ *
+ * BPF_PROG_LOAD
+ *	Description
+ *		Verify and load an eBPF program, returning a new file
+ *		descriptor associated with the program.
+ *
+ *		Applying **close**\ (2) to the file descriptor returned by
+ *		**BPF_PROG_LOAD** will unload the eBPF program (but see NOTES).
+ *
+ *		The close-on-exec file descriptor flag (see **fcntl**\ (2)) is
+ *		automatically enabled for the new file descriptor.
+ *
+ *	Return
+ *		A new file descriptor (a nonnegative integer), or -1 if an
+ *		error occurred (in which case, *errno* is set appropriately).
+ *
+ * BPF_OBJ_PIN
+ *	Description
+ *		Pin an eBPF program or map referred by the specified *bpf_fd*
+ *		to the provided *pathname* on the filesystem.
+ *
+ *		The *pathname* argument must not contain a dot (".").
+ *
+ *		On success, *pathname* retains a reference to the eBPF object,
+ *		preventing deallocation of the object when the original
+ *		*bpf_fd* is closed. This allow the eBPF object to live beyond
+ *		**close**\ (\ *bpf_fd*\ ), and hence the lifetime of the parent
+ *		process.
+ *
+ *		Applying **unlink**\ (2) or similar calls to the *pathname*
+ *		unpins the object from the filesystem, removing the reference.
+ *		If no other file descriptors or filesystem nodes refer to the
+ *		same object, it will be deallocated (see NOTES).
+ *
+ *		The filesystem type for the parent directory of *pathname* must
+ *		be **BPF_FS_MAGIC**.
+ *
+ *	Return
+ *		Returns zero on success. On error, -1 is returned and *errno*
+ *		is set appropriately.
+ *
+ * BPF_OBJ_GET
+ *	Description
+ *		Open a file descriptor for the eBPF object pinned to the
+ *		specified *pathname*.
+ *
+ *	Return
+ *		A new file descriptor (a nonnegative integer), or -1 if an
+ *		error occurred (in which case, *errno* is set appropriately).
+ *
+ * BPF_PROG_ATTACH
+ *	Description
+ *		Attach an eBPF program to a *target_fd* at the specified
+ *		*attach_type* hook.
+ *
+ *		The *attach_type* specifies the eBPF attachment point to
+ *		attach the program to, and must be one of *bpf_attach_type*
+ *		(see below).
+ *
+ *		The *attach_bpf_fd* must be a valid file descriptor for a
+ *		loaded eBPF program of a cgroup, flow dissector, LIRC, sockmap
+ *		or sock_ops type corresponding to the specified *attach_type*.
+ *
+ *		The *target_fd* must be a valid file descriptor for a kernel
+ *		object which depends on the attach type of *attach_bpf_fd*:
+ *
+ *		**BPF_PROG_TYPE_CGROUP_DEVICE**,
+ *		**BPF_PROG_TYPE_CGROUP_SKB**,
+ *		**BPF_PROG_TYPE_CGROUP_SOCK**,
+ *		**BPF_PROG_TYPE_CGROUP_SOCK_ADDR**,
+ *		**BPF_PROG_TYPE_CGROUP_SOCKOPT**,
+ *		**BPF_PROG_TYPE_CGROUP_SYSCTL**,
+ *		**BPF_PROG_TYPE_SOCK_OPS**
+ *
+ *			Control Group v2 hierarchy with the eBPF controller
+ *			enabled. Requires the kernel to be compiled with
+ *			**CONFIG_CGROUP_BPF**.
+ *
+ *		**BPF_PROG_TYPE_FLOW_DISSECTOR**
+ *
+ *			Network namespace (eg /proc/self/ns/net).
+ *
+ *		**BPF_PROG_TYPE_LIRC_MODE2**
+ *
+ *			LIRC device path (eg /dev/lircN). Requires the kernel
+ *			to be compiled with **CONFIG_BPF_LIRC_MODE2**.
+ *
+ *		**BPF_PROG_TYPE_SK_SKB**,
+ *		**BPF_PROG_TYPE_SK_MSG**
+ *
+ *			eBPF map of socket type (eg **BPF_MAP_TYPE_SOCKHASH**).
+ *
+ *	Return
+ *		Returns zero on success. On error, -1 is returned and *errno*
+ *		is set appropriately.
+ *
+ * BPF_PROG_DETACH
+ *	Description
+ *		Detach the eBPF program associated with the *target_fd* at the
+ *		hook specified by *attach_type*. The program must have been
+ *		previously attached using **BPF_PROG_ATTACH**.
+ *
+ *	Return
+ *		Returns zero on success. On error, -1 is returned and *errno*
+ *		is set appropriately.
+ *
+ * BPF_PROG_TEST_RUN
+ *	Description
+ *		Run the eBPF program associated with the *prog_fd* a *repeat*
+ *		number of times against a provided program context *ctx_in* and
+ *		data *data_in*, and return the modified program context
+ *		*ctx_out*, *data_out* (for example, packet data), result of the
+ *		execution *retval*, and *duration* of the test run.
+ *
+ *	Return
+ *		Returns zero on success. On error, -1 is returned and *errno*
+ *		is set appropriately.
+ *
+ *		**ENOSPC**
+ *			Either *data_size_out* or *ctx_size_out* is too small.
+ *		**ENOTSUPP**
+ *			This command is not supported by the program type of
+ *			the program referred to by *prog_fd*.
+ *
+ * BPF_PROG_GET_NEXT_ID
+ *	Description
+ *		Fetch the next eBPF program currently loaded into the kernel.
+ *
+ *		Looks for the eBPF program with an id greater than *start_id*
+ *		and updates *next_id* on success. If no other eBPF programs
+ *		remain with ids higher than *start_id*, returns -1 and sets
+ *		*errno* to **ENOENT**.
+ *
+ *	Return
+ *		Returns zero on success. On error, or when no id remains, -1
+ *		is returned and *errno* is set appropriately.
+ *
+ * BPF_MAP_GET_NEXT_ID
+ *	Description
+ *		Fetch the next eBPF map currently loaded into the kernel.
+ *
+ *		Looks for the eBPF map with an id greater than *start_id*
+ *		and updates *next_id* on success. If no other eBPF maps
+ *		remain with ids higher than *start_id*, returns -1 and sets
+ *		*errno* to **ENOENT**.
+ *
+ *	Return
+ *		Returns zero on success. On error, or when no id remains, -1
+ *		is returned and *errno* is set appropriately.
+ *
+ * BPF_PROG_GET_FD_BY_ID
+ *	Description
+ *		Open a file descriptor for the eBPF program corresponding to
+ *		*prog_id*.
+ *
+ *	Return
+ *		A new file descriptor (a nonnegative integer), or -1 if an
+ *		error occurred (in which case, *errno* is set appropriately).
+ *
+ * BPF_MAP_GET_FD_BY_ID
+ *	Description
+ *		Open a file descriptor for the eBPF map corresponding to
+ *		*map_id*.
+ *
+ *	Return
+ *		A new file descriptor (a nonnegative integer), or -1 if an
+ *		error occurred (in which case, *errno* is set appropriately).
+ *
+ * BPF_OBJ_GET_INFO_BY_FD
+ *	Description
+ *		Obtain information about the eBPF object corresponding to
+ *		*bpf_fd*.
+ *
+ *		Populates up to *info_len* bytes of *info*, which will be in
+ *		one of the following formats depending on the eBPF object type
+ *		of *bpf_fd*:
+ *
+ *		* **struct bpf_prog_info**
+ *		* **struct bpf_map_info**
+ *		* **struct bpf_btf_info**
+ *		* **struct bpf_link_info**
+ *
+ *	Return
+ *		Returns zero on success. On error, -1 is returned and *errno*
+ *		is set appropriately.
+ *
+ * BPF_PROG_QUERY
+ *	Description
+ *		Obtain information about eBPF programs associated with the
+ *		specified *attach_type* hook.
+ *
+ *		The *target_fd* must be a valid file descriptor for a kernel
+ *		object which depends on the attach type of *attach_bpf_fd*:
+ *
+ *		**BPF_PROG_TYPE_CGROUP_DEVICE**,
+ *		**BPF_PROG_TYPE_CGROUP_SKB**,
+ *		**BPF_PROG_TYPE_CGROUP_SOCK**,
+ *		**BPF_PROG_TYPE_CGROUP_SOCK_ADDR**,
+ *		**BPF_PROG_TYPE_CGROUP_SOCKOPT**,
+ *		**BPF_PROG_TYPE_CGROUP_SYSCTL**,
+ *		**BPF_PROG_TYPE_SOCK_OPS**
+ *
+ *			Control Group v2 hierarchy with the eBPF controller
+ *			enabled. Requires the kernel to be compiled with
+ *			**CONFIG_CGROUP_BPF**.
+ *
+ *		**BPF_PROG_TYPE_FLOW_DISSECTOR**
+ *
+ *			Network namespace (eg /proc/self/ns/net).
+ *
+ *		**BPF_PROG_TYPE_LIRC_MODE2**
+ *
+ *			LIRC device path (eg /dev/lircN). Requires the kernel
+ *			to be compiled with **CONFIG_BPF_LIRC_MODE2**.
+ *
+ *		**BPF_PROG_QUERY** always fetches the number of programs
+ *		attached and the *attach_flags* which were used to attach those
+ *		programs. Additionally, if *prog_ids* is nonzero and the number
+ *		of attached programs is less than *prog_cnt*, populates
+ *		*prog_ids* with the eBPF program ids of the programs attached
+ *		at *target_fd*.
+ *
+ *		The following flags may alter the result:
+ *
+ *		**BPF_F_QUERY_EFFECTIVE**
+ *			Only return information regarding programs which are
+ *			currently effective at the specified *target_fd*.
+ *
+ *	Return
+ *		Returns zero on success. On error, -1 is returned and *errno*
+ *		is set appropriately.
+ *
+ * BPF_RAW_TRACEPOINT_OPEN
+ *	Description
+ *		Attach an eBPF program to a tracepoint *name* to access kernel
+ *		internal arguments of the tracepoint in their raw form.
+ *
+ *		The *prog_fd* must be a valid file descriptor associated with
+ *		a loaded eBPF program of type **BPF_PROG_TYPE_RAW_TRACEPOINT**.
+ *
+ *		No ABI guarantees are made about the content of tracepoint
+ *		arguments exposed to the corresponding eBPF program.
+ *
+ *		Applying **close**\ (2) to the file descriptor returned by
+ *		**BPF_RAW_TRACEPOINT_OPEN** will delete the map (but see NOTES).
+ *
+ *	Return
+ *		A new file descriptor (a nonnegative integer), or -1 if an
+ *		error occurred (in which case, *errno* is set appropriately).
+ *
+ * BPF_BTF_LOAD
+ *	Description
+ *		Verify and load BPF Type Format (BTF) metadata into the kernel,
+ *		returning a new file descriptor associated with the metadata.
+ *		BTF is described in more detail at
+ *		https://www.kernel.org/doc/html/latest/bpf/btf.html.
+ *
+ *		The *btf* parameter must point to valid memory providing
+ *		*btf_size* bytes of BTF binary metadata.
+ *
+ *		The returned file descriptor can be passed to other **bpf**\ ()
+ *		subcommands such as **BPF_PROG_LOAD** or **BPF_MAP_CREATE** to
+ *		associate the BTF with those objects.
+ *
+ *		Similar to **BPF_PROG_LOAD**, **BPF_BTF_LOAD** has optional
+ *		parameters to specify a *btf_log_buf*, *btf_log_size* and
+ *		*btf_log_level* which allow the kernel to return freeform log
+ *		output regarding the BTF verification process.
+ *
+ *	Return
+ *		A new file descriptor (a nonnegative integer), or -1 if an
+ *		error occurred (in which case, *errno* is set appropriately).
+ *
+ * BPF_BTF_GET_FD_BY_ID
+ *	Description
+ *		Open a file descriptor for the BPF Type Format (BTF)
+ *		corresponding to *btf_id*.
+ *
+ *	Return
+ *		A new file descriptor (a nonnegative integer), or -1 if an
+ *		error occurred (in which case, *errno* is set appropriately).
+ *
+ * BPF_TASK_FD_QUERY
+ *	Description
+ *		Obtain information about eBPF programs associated with the
+ *		target process identified by *pid* and *fd*.
+ *
+ *		If the *pid* and *fd* are associated with a tracepoint, kprobe
+ *		or uprobe perf event, then the *prog_id* and *fd_type* will
+ *		be populated with the eBPF program id and file descriptor type
+ *		of type **bpf_task_fd_type**. If associated with a kprobe or
+ *		uprobe, the  *probe_offset* and *probe_addr* will also be
+ *		populated. Optionally, if *buf* is provided, then up to
+ *		*buf_len* bytes of *buf* will be populated with the name of
+ *		the tracepoint, kprobe or uprobe.
+ *
+ *		The resulting *prog_id* may be introspected in deeper detail
+ *		using **BPF_PROG_GET_FD_BY_ID** and **BPF_OBJ_GET_INFO_BY_FD**.
+ *
+ *	Return
+ *		Returns zero on success. On error, -1 is returned and *errno*
+ *		is set appropriately.
+ *
+ * BPF_MAP_LOOKUP_AND_DELETE_ELEM
+ *	Description
+ *		Look up an element with the given *key* in the map referred to
+ *		by the file descriptor *fd*, and if found, delete the element.
+ *
+ *		The **BPF_MAP_TYPE_QUEUE** and **BPF_MAP_TYPE_STACK** map types
+ *		implement this command as a "pop" operation, deleting the top
+ *		element rather than one corresponding to *key*.
+ *		The *key* and *key_len* parameters should be zeroed when
+ *		issuing this operation for these map types.
+ *
+ *		This command is only valid for the following map types:
+ *		* **BPF_MAP_TYPE_QUEUE**
+ *		* **BPF_MAP_TYPE_STACK**
+ *
+ *	Return
+ *		Returns zero on success. On error, -1 is returned and *errno*
+ *		is set appropriately.
+ *
+ * BPF_MAP_FREEZE
+ *	Description
+ *		Freeze the permissions of the specified map.
+ *
+ *		Write permissions may be frozen by passing zero *flags*.
+ *		Upon success, no future syscall invocations may alter the
+ *		map state of *map_fd*. Write operations from eBPF programs
+ *		are still possible for a frozen map.
+ *
+ *		Not supported for maps of type **BPF_MAP_TYPE_STRUCT_OPS**.
+ *
+ *	Return
+ *		Returns zero on success. On error, -1 is returned and *errno*
+ *		is set appropriately.
+ *
+ * BPF_BTF_GET_NEXT_ID
+ *	Description
+ *		Fetch the next BPF Type Format (BTF) object currently loaded
+ *		into the kernel.
+ *
+ *		Looks for the BTF object with an id greater than *start_id*
+ *		and updates *next_id* on success. If no other BTF objects
+ *		remain with ids higher than *start_id*, returns -1 and sets
+ *		*errno* to **ENOENT**.
+ *
+ *	Return
+ *		Returns zero on success. On error, or when no id remains, -1
+ *		is returned and *errno* is set appropriately.
+ *
+ * BPF_MAP_LOOKUP_BATCH
+ *	Description
+ *		Iterate and fetch multiple elements in a map.
+ *
+ *		Two opaque values are used to manage batch operations,
+ *		*in_batch* and *out_batch*. Initially, *in_batch* must be set
+ *		to NULL to begin the batched operation. After each subsequent
+ *		**BPF_MAP_LOOKUP_BATCH**, the caller should pass the resultant
+ *		*out_batch* as the *in_batch* for the next operation to
+ *		continue iteration from the current point.
+ *
+ *		The *keys* and *values* are output parameters which must point
+ *		to memory large enough to hold *count* items based on the key
+ *		and value size of the map *map_fd*. The *keys* buffer must be
+ *		of *key_size* * *count*. The *values* buffer must be of
+ *		*value_size* * *count*.
+ *
+ *		The *elem_flags* argument may be specified as one of the
+ *		following:
+ *
+ *		**BPF_F_LOCK**
+ *			Look up the value of a spin-locked map without
+ *			returning the lock. This must be specified if the
+ *			elements contain a spinlock.
+ *
+ *		On success, *count* elements from the map are copied into the
+ *		user buffer, with the keys copied into *keys* and the values
+ *		copied into the corresponding indices in *values*.
+ *
+ *		If an error is returned and *errno* is not **EFAULT**, *count*
+ *		is set to the number of successfully processed elements.
+ *
+ *	Return
+ *		Returns zero on success. On error, -1 is returned and *errno*
+ *		is set appropriately.
+ *
+ *		May set *errno* to **ENOSPC** to indicate that *keys* or
+ *		*values* is too small to dump an entire bucket during
+ *		iteration of a hash-based map type.
+ *
+ * BPF_MAP_LOOKUP_AND_DELETE_BATCH
+ *	Description
+ *		Iterate and delete all elements in a map.
+ *
+ *		This operation has the same behavior as
+ *		**BPF_MAP_LOOKUP_BATCH** with two exceptions:
+ *
+ *		* Every element that is successfully returned is also deleted
+ *		  from the map. This is at least *count* elements. Note that
+ *		  *count* is both an input and an output parameter.
+ *		* Upon returning with *errno* set to **EFAULT**, up to
+ *		  *count* elements may be deleted without returning the keys
+ *		  and values of the deleted elements.
+ *
+ *	Return
+ *		Returns zero on success. On error, -1 is returned and *errno*
+ *		is set appropriately.
+ *
+ * BPF_MAP_UPDATE_BATCH
+ *	Description
+ *		Update multiple elements in a map by *key*.
+ *
+ *		The *keys* and *values* are input parameters which must point
+ *		to memory large enough to hold *count* items based on the key
+ *		and value size of the map *map_fd*. The *keys* buffer must be
+ *		of *key_size* * *count*. The *values* buffer must be of
+ *		*value_size* * *count*.
+ *
+ *		Each element specified in *keys* is sequentially updated to the
+ *		value in the corresponding index in *values*. The *in_batch*
+ *		and *out_batch* parameters are ignored and should be zeroed.
+ *
+ *		The *elem_flags* argument should be specified as one of the
+ *		following:
+ *
+ *		**BPF_ANY**
+ *			Create new elements or update a existing elements.
+ *		**BPF_NOEXIST**
+ *			Create new elements only if they do not exist.
+ *		**BPF_EXIST**
+ *			Update existing elements.
+ *		**BPF_F_LOCK**
+ *			Update spin_lock-ed map elements. This must be
+ *			specified if the map value contains a spinlock.
+ *
+ *		On success, *count* elements from the map are updated.
+ *
+ *		If an error is returned and *errno* is not **EFAULT**, *count*
+ *		is set to the number of successfully processed elements.
+ *
+ *	Return
+ *		Returns zero on success. On error, -1 is returned and *errno*
+ *		is set appropriately.
+ *
+ *		May set *errno* to **EINVAL**, **EPERM**, **ENOMEM**, or
+ *		**E2BIG**. **E2BIG** indicates that the number of elements in
+ *		the map reached the *max_entries* limit specified at map
+ *		creation time.
+ *
+ *		May set *errno* to one of the following error codes under
+ *		specific circumstances:
+ *
+ *		**EEXIST**
+ *			If *flags* specifies **BPF_NOEXIST** and the element
+ *			with *key* already exists in the map.
+ *		**ENOENT**
+ *			If *flags* specifies **BPF_EXIST** and the element with
+ *			*key* does not exist in the map.
+ *
+ * BPF_MAP_DELETE_BATCH
+ *	Description
+ *		Delete multiple elements in a map by *key*.
+ *
+ *		The *keys* parameter is an input parameter which must point
+ *		to memory large enough to hold *count* items based on the key
+ *		size of the map *map_fd*, that is, *key_size* * *count*.
+ *
+ *		Each element specified in *keys* is sequentially deleted. The
+ *		*in_batch*, *out_batch*, and *values* parameters are ignored
+ *		and should be zeroed.
+ *
+ *		The *elem_flags* argument may be specified as one of the
+ *		following:
+ *
+ *		**BPF_F_LOCK**
+ *			Look up the value of a spin-locked map without
+ *			returning the lock. This must be specified if the
+ *			elements contain a spinlock.
+ *
+ *		On success, *count* elements from the map are updated.
+ *
+ *		If an error is returned and *errno* is not **EFAULT**, *count*
+ *		is set to the number of successfully processed elements. If
+ *		*errno* is **EFAULT**, up to *count* elements may be been
+ *		deleted.
+ *
+ *	Return
+ *		Returns zero on success. On error, -1 is returned and *errno*
+ *		is set appropriately.
+ *
+ * BPF_LINK_CREATE
+ *	Description
+ *		Attach an eBPF program to a *target_fd* at the specified
+ *		*attach_type* hook and return a file descriptor handle for
+ *		managing the link.
+ *
+ *	Return
+ *		A new file descriptor (a nonnegative integer), or -1 if an
+ *		error occurred (in which case, *errno* is set appropriately).
+ *
+ * BPF_LINK_UPDATE
+ *	Description
+ *		Update the eBPF program in the specified *link_fd* to
+ *		*new_prog_fd*.
+ *
+ *	Return
+ *		Returns zero on success. On error, -1 is returned and *errno*
+ *		is set appropriately.
+ *
+ * BPF_LINK_GET_FD_BY_ID
+ *	Description
+ *		Open a file descriptor for the eBPF Link corresponding to
+ *		*link_id*.
+ *
+ *	Return
+ *		A new file descriptor (a nonnegative integer), or -1 if an
+ *		error occurred (in which case, *errno* is set appropriately).
+ *
+ * BPF_LINK_GET_NEXT_ID
+ *	Description
+ *		Fetch the next eBPF link currently loaded into the kernel.
+ *
+ *		Looks for the eBPF link with an id greater than *start_id*
+ *		and updates *next_id* on success. If no other eBPF links
+ *		remain with ids higher than *start_id*, returns -1 and sets
+ *		*errno* to **ENOENT**.
+ *
+ *	Return
+ *		Returns zero on success. On error, or when no id remains, -1
+ *		is returned and *errno* is set appropriately.
+ *
+ * BPF_ENABLE_STATS
+ *	Description
+ *		Enable eBPF runtime statistics gathering.
+ *
+ *		Runtime statistics gathering for the eBPF runtime is disabled
+ *		by default to minimize the corresponding performance overhead.
+ *		This command enables statistics globally.
+ *
+ *		Multiple programs may independently enable statistics.
+ *		After gathering the desired statistics, eBPF runtime statistics
+ *		may be disabled again by calling **close**\ (2) for the file
+ *		descriptor returned by this function. Statistics will only be
+ *		disabled system-wide when all outstanding file descriptors
+ *		returned by prior calls for this subcommand are closed.
+ *
+ *	Return
+ *		A new file descriptor (a nonnegative integer), or -1 if an
+ *		error occurred (in which case, *errno* is set appropriately).
+ *
+ * BPF_ITER_CREATE
+ *	Description
+ *		Create an iterator on top of the specified *link_fd* (as
+ *		previously created using **BPF_LINK_CREATE**) and return a
+ *		file descriptor that can be used to trigger the iteration.
+ *
+ *		If the resulting file descriptor is pinned to the filesystem
+ *		using  **BPF_OBJ_PIN**, then subsequent **read**\ (2) syscalls
+ *		for that path will trigger the iterator to read kernel state
+ *		using the eBPF program attached to *link_fd*.
+ *
+ *	Return
+ *		A new file descriptor (a nonnegative integer), or -1 if an
+ *		error occurred (in which case, *errno* is set appropriately).
+ *
+ * BPF_LINK_DETACH
+ *	Description
+ *		Forcefully detach the specified *link_fd* from its
+ *		corresponding attachment point.
+ *
+ *	Return
+ *		Returns zero on success. On error, -1 is returned and *errno*
+ *		is set appropriately.
+ *
+ * BPF_PROG_BIND_MAP
+ *	Description
+ *		Bind a map to the lifetime of an eBPF program.
+ *
+ *		The map identified by *map_fd* is bound to the program
+ *		identified by *prog_fd* and only released when *prog_fd* is
+ *		released. This may be used in cases where metadata should be
+ *		associated with a program which otherwise does not contain any
+ *		references to the map (for example, embedded in the eBPF
+ *		program instructions).
+ *
+ *	Return
+ *		Returns zero on success. On error, -1 is returned and *errno*
+ *		is set appropriately.
+ *
+ * NOTES
+ *	eBPF objects (maps and programs) can be shared between processes.
+ *
+ *	* After **fork**\ (2), the child inherits file descriptors
+ *	  referring to the same eBPF objects.
+ *	* File descriptors referring to eBPF objects can be transferred over
+ *	  **unix**\ (7) domain sockets.
+ *	* File descriptors referring to eBPF objects can be duplicated in the
+ *	  usual way, using **dup**\ (2) and similar calls.
+ *	* File descriptors referring to eBPF objects can be pinned to the
+ *	  filesystem using the **BPF_OBJ_PIN** command of **bpf**\ (2).
+ *
+ *	An eBPF object is deallocated only after all file descriptors referring
+ *	to the object have been closed and no references remain pinned to the
+ *	filesystem or attached (for example, bound to a program or device).
+ */
 enum bpf_cmd {
 	BPF_MAP_CREATE,
 	BPF_MAP_LOOKUP_ELEM,
@@ -729,7 +1439,7 @@ union bpf_attr {
  * parsed and used to produce a manual page. The workflow is the following,
  * and requires the rst2man utility:
  *
- *     $ ./scripts/bpf_helpers_doc.py \
+ *     $ ./scripts/bpf_doc.py \
  *             --filename include/uapi/linux/bpf.h > /tmp/bpf-helpers.rst
  *     $ rst2man /tmp/bpf-helpers.rst > /tmp/bpf-helpers.7
  *     $ man /tmp/bpf-helpers.7

scripts/bpf_helpers_doc.py → scripts/bpf_doc.py

@@ -2,6 +2,7 @@
 # SPDX-License-Identifier: GPL-2.0-only
 #
 # Copyright (C) 2018-2019 Netronome Systems, Inc.
+# Copyright (C) 2021 Isovalent, Inc.
 
 # In case user attempts to run with Python 2.
 from __future__ import print_function
@@ -13,6 +14,9 @@ import sys, os
 class NoHelperFound(BaseException):
     pass
 
+class NoSyscallCommandFound(BaseException):
+    pass
+
 class ParsingError(BaseException):
     def __init__(self, line='<line not provided>', reader=None):
         if reader:
@@ -22,18 +26,27 @@ class ParsingError(BaseException):
         else:
             BaseException.__init__(self, 'Error parsing line: %s' % line)
 
-class Helper(object):
+
+class APIElement(object):
     """
-    An object representing the description of an eBPF helper function.
-    @proto: function prototype of the helper function
-    @desc: textual description of the helper function
-    @ret: description of the return value of the helper function
+    An object representing the description of an aspect of the eBPF API.
+    @proto: prototype of the API symbol
+    @desc: textual description of the symbol
+    @ret: (optional) description of any associated return value
     """
     def __init__(self, proto='', desc='', ret=''):
         self.proto = proto
         self.desc = desc
         self.ret = ret
 
+
+class Helper(APIElement):
+    """
+    An object representing the description of an eBPF helper function.
+    @proto: function prototype of the helper function
+    @desc: textual description of the helper function
+    @ret: description of the return value of the helper function
+    """
     def proto_break_down(self):
         """
         Break down helper function protocol into smaller chunks: return type,
@@ -60,6 +73,7 @@ class Helper(object):
 
         return res
 
+
 class HeaderParser(object):
     """
     An object used to parse a file in order to extract the documentation of a
@@ -72,6 +86,13 @@ class HeaderParser(object):
         self.reader = open(filename, 'r')
         self.line = ''
         self.helpers = []
+        self.commands = []
+
+    def parse_element(self):
+        proto    = self.parse_symbol()
+        desc     = self.parse_desc()
+        ret      = self.parse_ret()
+        return APIElement(proto=proto, desc=desc, ret=ret)
 
     def parse_helper(self):
         proto    = self.parse_proto()
@@ -79,6 +100,18 @@ class HeaderParser(object):
         ret      = self.parse_ret()
         return Helper(proto=proto, desc=desc, ret=ret)
 
+    def parse_symbol(self):
+        p = re.compile(' \* ?(.+)$')
+        capture = p.match(self.line)
+        if not capture:
+            raise NoSyscallCommandFound
+        end_re = re.compile(' \* ?NOTES$')
+        end = end_re.match(self.line)
+        if end:
+            raise NoSyscallCommandFound
+        self.line = self.reader.readline()
+        return capture.group(1)
+
     def parse_proto(self):
         # Argument can be of shape:
         #   - "void"
@@ -140,16 +173,29 @@ class HeaderParser(object):
                     break
         return ret
 
-    def run(self):
-        # Advance to start of helper function descriptions.
-        offset = self.reader.read().find('* Start of BPF helper function descriptions:')
+    def seek_to(self, target, help_message):
+        self.reader.seek(0)
+        offset = self.reader.read().find(target)
         if offset == -1:
-            raise Exception('Could not find start of eBPF helper descriptions list')
+            raise Exception(help_message)
         self.reader.seek(offset)
         self.reader.readline()
         self.reader.readline()
         self.line = self.reader.readline()
 
+    def parse_syscall(self):
+        self.seek_to('* DOC: eBPF Syscall Commands',
+                     'Could not find start of eBPF syscall descriptions list')
+        while True:
+            try:
+                command = self.parse_element()
+                self.commands.append(command)
+            except NoSyscallCommandFound:
+                break
+
+    def parse_helpers(self):
+        self.seek_to('* Start of BPF helper function descriptions:',
+                     'Could not find start of eBPF helper descriptions list')
         while True:
             try:
                 helper = self.parse_helper()
@@ -157,6 +203,9 @@ class HeaderParser(object):
             except NoHelperFound:
                 break
 
+    def run(self):
+        self.parse_syscall()
+        self.parse_helpers()
         self.reader.close()
 
 ###############################################################################
@@ -165,10 +214,11 @@ class Printer(object):
     """
     A generic class for printers. Printers should be created with an array of
     Helper objects, and implement a way to print them in the desired fashion.
-    @helpers: array of Helper objects to print to standard output
+    @parser: A HeaderParser with objects to print to standard output
     """
-    def __init__(self, helpers):
-        self.helpers = helpers
+    def __init__(self, parser):
+        self.parser = parser
+        self.elements = []
 
     def print_header(self):
         pass
@@ -181,19 +231,23 @@ class Printer(object):
 
     def print_all(self):
         self.print_header()
-        for helper in self.helpers:
-            self.print_one(helper)
+        for elem in self.elements:
+            self.print_one(elem)
         self.print_footer()
 
+
 class PrinterRST(Printer):
     """
-    A printer for dumping collected information about helpers as a ReStructured
-    Text page compatible with the rst2man program, which can be used to
-    generate a manual page for the helpers.
-    @helpers: array of Helper objects to print to standard output
+    A generic class for printers that print ReStructured Text. Printers should
+    be created with a HeaderParser object, and implement a way to print API
+    elements in the desired fashion.
+    @parser: A HeaderParser with objects to print to standard output
     """
-    def print_header(self):
-        header = '''\
+    def __init__(self, parser):
+        self.parser = parser
+
+    def print_license(self):
+        license = '''\
 .. Copyright (C) All BPF authors and contributors from 2014 to present.
 .. See git log include/uapi/linux/bpf.h in kernel tree for details.
 .. 
@@ -221,9 +275,39 @@ class PrinterRST(Printer):
 .. 
 .. Please do not edit this file. It was generated from the documentation
 .. located in file include/uapi/linux/bpf.h of the Linux kernel sources
-.. (helpers description), and from scripts/bpf_helpers_doc.py in the same
+.. (helpers description), and from scripts/bpf_doc.py in the same
 .. repository (header and footer).
+'''
+        print(license)
 
+    def print_elem(self, elem):
+        if (elem.desc):
+            print('\tDescription')
+            # Do not strip all newline characters: formatted code at the end of
+            # a section must be followed by a blank line.
+            for line in re.sub('\n$', '', elem.desc, count=1).split('\n'):
+                print('{}{}'.format('\t\t' if line else '', line))
+
+        if (elem.ret):
+            print('\tReturn')
+            for line in elem.ret.rstrip().split('\n'):
+                print('{}{}'.format('\t\t' if line else '', line))
+
+        print('')
+
+
+class PrinterHelpersRST(PrinterRST):
+    """
+    A printer for dumping collected information about helpers as a ReStructured
+    Text page compatible with the rst2man program, which can be used to
+    generate a manual page for the helpers.
+    @parser: A HeaderParser with Helper objects to print to standard output
+    """
+    def __init__(self, parser):
+        self.elements = parser.helpers
+
+    def print_header(self):
+        header = '''\
 ===========
 BPF-HELPERS
 ===========
@@ -264,6 +348,7 @@ kernel at the top).
 HELPERS
 =======
 '''
+        PrinterRST.print_license(self)
         print(header)
 
     def print_footer(self):
@@ -380,27 +465,50 @@ SEE ALSO
 
     def print_one(self, helper):
         self.print_proto(helper)
+        self.print_elem(helper)
 
-        if (helper.desc):
-            print('\tDescription')
-            # Do not strip all newline characters: formatted code at the end of
-            # a section must be followed by a blank line.
-            for line in re.sub('\n$', '', helper.desc, count=1).split('\n'):
-                print('{}{}'.format('\t\t' if line else '', line))
 
-        if (helper.ret):
-            print('\tReturn')
-            for line in helper.ret.rstrip().split('\n'):
-                print('{}{}'.format('\t\t' if line else '', line))
+class PrinterSyscallRST(PrinterRST):
+    """
+    A printer for dumping collected information about the syscall API as a
+    ReStructured Text page compatible with the rst2man program, which can be
+    used to generate a manual page for the syscall.
+    @parser: A HeaderParser with APIElement objects to print to standard
+             output
+    """
+    def __init__(self, parser):
+        self.elements = parser.commands
+
+    def print_header(self):
+        header = '''\
+===
+bpf
+===
+-------------------------------------------------------------------------------
+Perform a command on an extended BPF object
+-------------------------------------------------------------------------------
+
+:Manual section: 2
+
+COMMANDS
+========
+'''
+        PrinterRST.print_license(self)
+        print(header)
+
+    def print_one(self, command):
+        print('**%s**' % (command.proto))
+        self.print_elem(command)
 
-        print('')
 
 class PrinterHelpers(Printer):
     """
     A printer for dumping collected information about helpers as C header to
     be included from BPF program.
-    @helpers: array of Helper objects to print to standard output
+    @parser: A HeaderParser with Helper objects to print to standard output
     """
+    def __init__(self, parser):
+        self.elements = parser.helpers
 
     type_fwds = [
             'struct bpf_fib_lookup',
@@ -511,7 +619,7 @@ class PrinterHelpers(Printer):
 
     def print_header(self):
         header = '''\
-/* This is auto-generated file. See bpf_helpers_doc.py for details. */
+/* This is auto-generated file. See bpf_doc.py for details. */
 
 /* Forward declarations of BPF structs */'''
 
@@ -589,8 +697,13 @@ script = os.path.abspath(sys.argv[0])
 linuxRoot = os.path.dirname(os.path.dirname(script))
 bpfh = os.path.join(linuxRoot, 'include/uapi/linux/bpf.h')
 
+printers = {
+        'helpers': PrinterHelpersRST,
+        'syscall': PrinterSyscallRST,
+}
+
 argParser = argparse.ArgumentParser(description="""
-Parse eBPF header file and generate documentation for eBPF helper functions.
+Parse eBPF header file and generate documentation for the eBPF API.
 The RST-formatted output produced can be turned into a manual page with the
 rst2man utility.
 """)
@@ -601,6 +714,8 @@ if (os.path.isfile(bpfh)):
                            default=bpfh)
 else:
     argParser.add_argument('--filename', help='path to include/uapi/linux/bpf.h')
+argParser.add_argument('target', nargs='?', default='helpers',
+                       choices=printers.keys(), help='eBPF API target')
 args = argParser.parse_args()
 
 # Parse file.
@@ -609,7 +724,9 @@ headerParser.run()
 
 # Print formatted output to standard output.
 if args.header:
-    printer = PrinterHelpers(headerParser.helpers)
+    if args.target != 'helpers':
+        raise NotImplementedError('Only helpers header generation is supported')
+    printer = PrinterHelpers(headerParser)
 else:
-    printer = PrinterRST(headerParser.helpers)
+    printer = printers[args.target](headerParser)
 printer.print_all()

tools/bpf/Makefile.helpers

-# SPDX-License-Identifier: GPL-2.0-only
-ifndef allow-override
-  include ../scripts/Makefile.include
-  include ../scripts/utilities.mak
-else
-  # Assume Makefile.helpers is being run from bpftool/Documentation
-  # subdirectory. Go up two more directories to fetch bpf.h header and
-  # associated script.
-  UP2DIR := ../../
-endif
-
-INSTALL ?= install
-RM ?= rm -f
-RMDIR ?= rmdir --ignore-fail-on-non-empty
-
-ifeq ($(V),1)
-  Q =
-else
-  Q = @
-endif
-
-prefix ?= /usr/local
-mandir ?= $(prefix)/man
-man7dir = $(mandir)/man7
-
-HELPERS_RST = bpf-helpers.rst
-MAN7_RST = $(HELPERS_RST)
-
-_DOC_MAN7 = $(patsubst %.rst,%.7,$(MAN7_RST))
-DOC_MAN7 = $(addprefix $(OUTPUT),$(_DOC_MAN7))
-
-helpers: man7
-man7: $(DOC_MAN7)
-
-RST2MAN_DEP := $(shell command -v rst2man 2>/dev/null)
-
-$(OUTPUT)$(HELPERS_RST): $(UP2DIR)../../include/uapi/linux/bpf.h
-	$(QUIET_GEN)$(UP2DIR)../../scripts/bpf_helpers_doc.py --filename $< > $@
-
-$(OUTPUT)%.7: $(OUTPUT)%.rst
-ifndef RST2MAN_DEP
-	$(error "rst2man not found, but required to generate man pages")
-endif
-	$(QUIET_GEN)rst2man $< > $@
-
-helpers-clean:
-	$(call QUIET_CLEAN, eBPF_helpers-manpage)
-	$(Q)$(RM) $(DOC_MAN7) $(OUTPUT)$(HELPERS_RST)
-
-helpers-install: helpers
-	$(call QUIET_INSTALL, eBPF_helpers-manpage)
-	$(Q)$(INSTALL) -d -m 755 $(DESTDIR)$(man7dir)
-	$(Q)$(INSTALL) -m 644 $(DOC_MAN7) $(DESTDIR)$(man7dir)
-
-helpers-uninstall:
-	$(call QUIET_UNINST, eBPF_helpers-manpage)
-	$(Q)$(RM) $(addprefix $(DESTDIR)$(man7dir)/,$(_DOC_MAN7))
-	$(Q)$(RMDIR) $(DESTDIR)$(man7dir)
-
-.PHONY: helpers helpers-clean helpers-install helpers-uninstall

tools/bpf/bpftool/.gitignore

@@ -3,7 +3,6 @@
 /bootstrap/
 /bpftool
 bpftool*.8
-bpf-helpers.*
 FEATURE-DUMP.bpftool
 feature
 libbpf

tools/bpf/bpftool/Documentation/Makefile

@@ -16,15 +16,12 @@ prefix ?= /usr/local
 mandir ?= $(prefix)/man
 man8dir = $(mandir)/man8
 
-# Load targets for building eBPF helpers man page.
-include ../../Makefile.helpers
-
 MAN8_RST = $(wildcard bpftool*.rst)
 
 _DOC_MAN8 = $(patsubst %.rst,%.8,$(MAN8_RST))
 DOC_MAN8 = $(addprefix $(OUTPUT),$(_DOC_MAN8))
 
-man: man8 helpers
+man: man8
 man8: $(DOC_MAN8)
 
 RST2MAN_DEP := $(shell command -v rst2man 2>/dev/null)
@@ -46,16 +43,16 @@ ifndef RST2MAN_DEP
 endif
 	$(QUIET_GEN)( cat $< ; printf "%b" $(call see_also,$<) ) | rst2man $(RST2MAN_OPTS) > $@
 
-clean: helpers-clean
+clean:
 	$(call QUIET_CLEAN, Documentation)
 	$(Q)$(RM) $(DOC_MAN8)
 
-install: man helpers-install
+install: man
 	$(call QUIET_INSTALL, Documentation-man)
 	$(Q)$(INSTALL) -d -m 755 $(DESTDIR)$(man8dir)
 	$(Q)$(INSTALL) -m 644 $(DOC_MAN8) $(DESTDIR)$(man8dir)
 
-uninstall: helpers-uninstall
+uninstall:
 	$(call QUIET_UNINST, Documentation-man)
 	$(Q)$(RM) $(addprefix $(DESTDIR)$(man8dir)/,$(_DOC_MAN8))
 	$(Q)$(RMDIR) $(DESTDIR)$(man8dir)

tools/include/uapi/linux/bpf.h

@@ -93,7 +93,717 @@ union bpf_iter_link_info {
 	} map;
 };
 
-/* BPF syscall commands, see bpf(2) man-page for details. */
+/* BPF syscall commands, see bpf(2) man-page for more details. */
+/**
+ * DOC: eBPF Syscall Preamble
+ *
+ * The operation to be performed by the **bpf**\ () system call is determined
+ * by the *cmd* argument. Each operation takes an accompanying argument,
+ * provided via *attr*, which is a pointer to a union of type *bpf_attr* (see
+ * below). The size argument is the size of the union pointed to by *attr*.
+ */
+/**
+ * DOC: eBPF Syscall Commands
+ *
+ * BPF_MAP_CREATE
+ *	Description
+ *		Create a map and return a file descriptor that refers to the
+ *		map. The close-on-exec file descriptor flag (see **fcntl**\ (2))
+ *		is automatically enabled for the new file descriptor.
+ *
+ *		Applying **close**\ (2) to the file descriptor returned by
+ *		**BPF_MAP_CREATE** will delete the map (but see NOTES).
+ *
+ *	Return
+ *		A new file descriptor (a nonnegative integer), or -1 if an
+ *		error occurred (in which case, *errno* is set appropriately).
+ *
+ * BPF_MAP_LOOKUP_ELEM
+ *	Description
+ *		Look up an element with a given *key* in the map referred to
+ *		by the file descriptor *map_fd*.
+ *
+ *		The *flags* argument may be specified as one of the
+ *		following:
+ *
+ *		**BPF_F_LOCK**
+ *			Look up the value of a spin-locked map without
+ *			returning the lock. This must be specified if the
+ *			elements contain a spinlock.
+ *
+ *	Return
+ *		Returns zero on success. On error, -1 is returned and *errno*
+ *		is set appropriately.
+ *
+ * BPF_MAP_UPDATE_ELEM
+ *	Description
+ *		Create or update an element (key/value pair) in a specified map.
+ *
+ *		The *flags* argument should be specified as one of the
+ *		following:
+ *
+ *		**BPF_ANY**
+ *			Create a new element or update an existing element.
+ *		**BPF_NOEXIST**
+ *			Create a new element only if it did not exist.
+ *		**BPF_EXIST**
+ *			Update an existing element.
+ *		**BPF_F_LOCK**
+ *			Update a spin_lock-ed map element.
+ *
+ *	Return
+ *		Returns zero on success. On error, -1 is returned and *errno*
+ *		is set appropriately.
+ *
+ *		May set *errno* to **EINVAL**, **EPERM**, **ENOMEM**,
+ *		**E2BIG**, **EEXIST**, or **ENOENT**.
+ *
+ *		**E2BIG**
+ *			The number of elements in the map reached the
+ *			*max_entries* limit specified at map creation time.
+ *		**EEXIST**
+ *			If *flags* specifies **BPF_NOEXIST** and the element
+ *			with *key* already exists in the map.
+ *		**ENOENT**
+ *			If *flags* specifies **BPF_EXIST** and the element with
+ *			*key* does not exist in the map.
+ *
+ * BPF_MAP_DELETE_ELEM
+ *	Description
+ *		Look up and delete an element by key in a specified map.
+ *
+ *	Return
+ *		Returns zero on success. On error, -1 is returned and *errno*
+ *		is set appropriately.
+ *
+ * BPF_MAP_GET_NEXT_KEY
+ *	Description
+ *		Look up an element by key in a specified map and return the key
+ *		of the next element. Can be used to iterate over all elements
+ *		in the map.
+ *
+ *	Return
+ *		Returns zero on success. On error, -1 is returned and *errno*
+ *		is set appropriately.
+ *
+ *		The following cases can be used to iterate over all elements of
+ *		the map:
+ *
+ *		* If *key* is not found, the operation returns zero and sets
+ *		  the *next_key* pointer to the key of the first element.
+ *		* If *key* is found, the operation returns zero and sets the
+ *		  *next_key* pointer to the key of the next element.
+ *		* If *key* is the last element, returns -1 and *errno* is set
+ *		  to **ENOENT**.
+ *
+ *		May set *errno* to **ENOMEM**, **EFAULT**, **EPERM**, or
+ *		**EINVAL** on error.
+ *
+ * BPF_PROG_LOAD
+ *	Description
+ *		Verify and load an eBPF program, returning a new file
+ *		descriptor associated with the program.
+ *
+ *		Applying **close**\ (2) to the file descriptor returned by
+ *		**BPF_PROG_LOAD** will unload the eBPF program (but see NOTES).
+ *
+ *		The close-on-exec file descriptor flag (see **fcntl**\ (2)) is
+ *		automatically enabled for the new file descriptor.
+ *
+ *	Return
+ *		A new file descriptor (a nonnegative integer), or -1 if an
+ *		error occurred (in which case, *errno* is set appropriately).
+ *
+ * BPF_OBJ_PIN
+ *	Description
+ *		Pin an eBPF program or map referred by the specified *bpf_fd*
+ *		to the provided *pathname* on the filesystem.
+ *
+ *		The *pathname* argument must not contain a dot (".").
+ *
+ *		On success, *pathname* retains a reference to the eBPF object,
+ *		preventing deallocation of the object when the original
+ *		*bpf_fd* is closed. This allow the eBPF object to live beyond
+ *		**close**\ (\ *bpf_fd*\ ), and hence the lifetime of the parent
+ *		process.
+ *
+ *		Applying **unlink**\ (2) or similar calls to the *pathname*
+ *		unpins the object from the filesystem, removing the reference.
+ *		If no other file descriptors or filesystem nodes refer to the
+ *		same object, it will be deallocated (see NOTES).
+ *
+ *		The filesystem type for the parent directory of *pathname* must
+ *		be **BPF_FS_MAGIC**.
+ *
+ *	Return
+ *		Returns zero on success. On error, -1 is returned and *errno*
+ *		is set appropriately.
+ *
+ * BPF_OBJ_GET
+ *	Description
+ *		Open a file descriptor for the eBPF object pinned to the
+ *		specified *pathname*.
+ *
+ *	Return
+ *		A new file descriptor (a nonnegative integer), or -1 if an
+ *		error occurred (in which case, *errno* is set appropriately).
+ *
+ * BPF_PROG_ATTACH
+ *	Description
+ *		Attach an eBPF program to a *target_fd* at the specified
+ *		*attach_type* hook.
+ *
+ *		The *attach_type* specifies the eBPF attachment point to
+ *		attach the program to, and must be one of *bpf_attach_type*
+ *		(see below).
+ *
+ *		The *attach_bpf_fd* must be a valid file descriptor for a
+ *		loaded eBPF program of a cgroup, flow dissector, LIRC, sockmap
+ *		or sock_ops type corresponding to the specified *attach_type*.
+ *
+ *		The *target_fd* must be a valid file descriptor for a kernel
+ *		object which depends on the attach type of *attach_bpf_fd*:
+ *
+ *		**BPF_PROG_TYPE_CGROUP_DEVICE**,
+ *		**BPF_PROG_TYPE_CGROUP_SKB**,
+ *		**BPF_PROG_TYPE_CGROUP_SOCK**,
+ *		**BPF_PROG_TYPE_CGROUP_SOCK_ADDR**,
+ *		**BPF_PROG_TYPE_CGROUP_SOCKOPT**,
+ *		**BPF_PROG_TYPE_CGROUP_SYSCTL**,
+ *		**BPF_PROG_TYPE_SOCK_OPS**
+ *
+ *			Control Group v2 hierarchy with the eBPF controller
+ *			enabled. Requires the kernel to be compiled with
+ *			**CONFIG_CGROUP_BPF**.
+ *
+ *		**BPF_PROG_TYPE_FLOW_DISSECTOR**
+ *
+ *			Network namespace (eg /proc/self/ns/net).
+ *
+ *		**BPF_PROG_TYPE_LIRC_MODE2**
+ *
+ *			LIRC device path (eg /dev/lircN). Requires the kernel
+ *			to be compiled with **CONFIG_BPF_LIRC_MODE2**.
+ *
+ *		**BPF_PROG_TYPE_SK_SKB**,
+ *		**BPF_PROG_TYPE_SK_MSG**
+ *
+ *			eBPF map of socket type (eg **BPF_MAP_TYPE_SOCKHASH**).
+ *
+ *	Return
+ *		Returns zero on success. On error, -1 is returned and *errno*
+ *		is set appropriately.
+ *
+ * BPF_PROG_DETACH
+ *	Description
+ *		Detach the eBPF program associated with the *target_fd* at the
+ *		hook specified by *attach_type*. The program must have been
+ *		previously attached using **BPF_PROG_ATTACH**.
+ *
+ *	Return
+ *		Returns zero on success. On error, -1 is returned and *errno*
+ *		is set appropriately.
+ *
+ * BPF_PROG_TEST_RUN
+ *	Description
+ *		Run the eBPF program associated with the *prog_fd* a *repeat*
+ *		number of times against a provided program context *ctx_in* and
+ *		data *data_in*, and return the modified program context
+ *		*ctx_out*, *data_out* (for example, packet data), result of the
+ *		execution *retval*, and *duration* of the test run.
+ *
+ *	Return
+ *		Returns zero on success. On error, -1 is returned and *errno*
+ *		is set appropriately.
+ *
+ *		**ENOSPC**
+ *			Either *data_size_out* or *ctx_size_out* is too small.
+ *		**ENOTSUPP**
+ *			This command is not supported by the program type of
+ *			the program referred to by *prog_fd*.
+ *
+ * BPF_PROG_GET_NEXT_ID
+ *	Description
+ *		Fetch the next eBPF program currently loaded into the kernel.
+ *
+ *		Looks for the eBPF program with an id greater than *start_id*
+ *		and updates *next_id* on success. If no other eBPF programs
+ *		remain with ids higher than *start_id*, returns -1 and sets
+ *		*errno* to **ENOENT**.
+ *
+ *	Return
+ *		Returns zero on success. On error, or when no id remains, -1
+ *		is returned and *errno* is set appropriately.
+ *
+ * BPF_MAP_GET_NEXT_ID
+ *	Description
+ *		Fetch the next eBPF map currently loaded into the kernel.
+ *
+ *		Looks for the eBPF map with an id greater than *start_id*
+ *		and updates *next_id* on success. If no other eBPF maps
+ *		remain with ids higher than *start_id*, returns -1 and sets
+ *		*errno* to **ENOENT**.
+ *
+ *	Return
+ *		Returns zero on success. On error, or when no id remains, -1
+ *		is returned and *errno* is set appropriately.
+ *
+ * BPF_PROG_GET_FD_BY_ID
+ *	Description
+ *		Open a file descriptor for the eBPF program corresponding to
+ *		*prog_id*.
+ *
+ *	Return
+ *		A new file descriptor (a nonnegative integer), or -1 if an
+ *		error occurred (in which case, *errno* is set appropriately).
+ *
+ * BPF_MAP_GET_FD_BY_ID
+ *	Description
+ *		Open a file descriptor for the eBPF map corresponding to
+ *		*map_id*.
+ *
+ *	Return
+ *		A new file descriptor (a nonnegative integer), or -1 if an
+ *		error occurred (in which case, *errno* is set appropriately).
+ *
+ * BPF_OBJ_GET_INFO_BY_FD
+ *	Description
+ *		Obtain information about the eBPF object corresponding to
+ *		*bpf_fd*.
+ *
+ *		Populates up to *info_len* bytes of *info*, which will be in
+ *		one of the following formats depending on the eBPF object type
+ *		of *bpf_fd*:
+ *
+ *		* **struct bpf_prog_info**
+ *		* **struct bpf_map_info**
+ *		* **struct bpf_btf_info**
+ *		* **struct bpf_link_info**
+ *
+ *	Return
+ *		Returns zero on success. On error, -1 is returned and *errno*
+ *		is set appropriately.
+ *
+ * BPF_PROG_QUERY
+ *	Description
+ *		Obtain information about eBPF programs associated with the
+ *		specified *attach_type* hook.
+ *
+ *		The *target_fd* must be a valid file descriptor for a kernel
+ *		object which depends on the attach type of *attach_bpf_fd*:
+ *
+ *		**BPF_PROG_TYPE_CGROUP_DEVICE**,
+ *		**BPF_PROG_TYPE_CGROUP_SKB**,
+ *		**BPF_PROG_TYPE_CGROUP_SOCK**,
+ *		**BPF_PROG_TYPE_CGROUP_SOCK_ADDR**,
+ *		**BPF_PROG_TYPE_CGROUP_SOCKOPT**,
+ *		**BPF_PROG_TYPE_CGROUP_SYSCTL**,
+ *		**BPF_PROG_TYPE_SOCK_OPS**
+ *
+ *			Control Group v2 hierarchy with the eBPF controller
+ *			enabled. Requires the kernel to be compiled with
+ *			**CONFIG_CGROUP_BPF**.
+ *
+ *		**BPF_PROG_TYPE_FLOW_DISSECTOR**
+ *
+ *			Network namespace (eg /proc/self/ns/net).
+ *
+ *		**BPF_PROG_TYPE_LIRC_MODE2**
+ *
+ *			LIRC device path (eg /dev/lircN). Requires the kernel
+ *			to be compiled with **CONFIG_BPF_LIRC_MODE2**.
+ *
+ *		**BPF_PROG_QUERY** always fetches the number of programs
+ *		attached and the *attach_flags* which were used to attach those
+ *		programs. Additionally, if *prog_ids* is nonzero and the number
+ *		of attached programs is less than *prog_cnt*, populates
+ *		*prog_ids* with the eBPF program ids of the programs attached
+ *		at *target_fd*.
+ *
+ *		The following flags may alter the result:
+ *
+ *		**BPF_F_QUERY_EFFECTIVE**
+ *			Only return information regarding programs which are
+ *			currently effective at the specified *target_fd*.
+ *
+ *	Return
+ *		Returns zero on success. On error, -1 is returned and *errno*
+ *		is set appropriately.
+ *
+ * BPF_RAW_TRACEPOINT_OPEN
+ *	Description
+ *		Attach an eBPF program to a tracepoint *name* to access kernel
+ *		internal arguments of the tracepoint in their raw form.
+ *
+ *		The *prog_fd* must be a valid file descriptor associated with
+ *		a loaded eBPF program of type **BPF_PROG_TYPE_RAW_TRACEPOINT**.
+ *
+ *		No ABI guarantees are made about the content of tracepoint
+ *		arguments exposed to the corresponding eBPF program.
+ *
+ *		Applying **close**\ (2) to the file descriptor returned by
+ *		**BPF_RAW_TRACEPOINT_OPEN** will delete the map (but see NOTES).
+ *
+ *	Return
+ *		A new file descriptor (a nonnegative integer), or -1 if an
+ *		error occurred (in which case, *errno* is set appropriately).
+ *
+ * BPF_BTF_LOAD
+ *	Description
+ *		Verify and load BPF Type Format (BTF) metadata into the kernel,
+ *		returning a new file descriptor associated with the metadata.
+ *		BTF is described in more detail at
+ *		https://www.kernel.org/doc/html/latest/bpf/btf.html.
+ *
+ *		The *btf* parameter must point to valid memory providing
+ *		*btf_size* bytes of BTF binary metadata.
+ *
+ *		The returned file descriptor can be passed to other **bpf**\ ()
+ *		subcommands such as **BPF_PROG_LOAD** or **BPF_MAP_CREATE** to
+ *		associate the BTF with those objects.
+ *
+ *		Similar to **BPF_PROG_LOAD**, **BPF_BTF_LOAD** has optional
+ *		parameters to specify a *btf_log_buf*, *btf_log_size* and
+ *		*btf_log_level* which allow the kernel to return freeform log
+ *		output regarding the BTF verification process.
+ *
+ *	Return
+ *		A new file descriptor (a nonnegative integer), or -1 if an
+ *		error occurred (in which case, *errno* is set appropriately).
+ *
+ * BPF_BTF_GET_FD_BY_ID
+ *	Description
+ *		Open a file descriptor for the BPF Type Format (BTF)
+ *		corresponding to *btf_id*.
+ *
+ *	Return
+ *		A new file descriptor (a nonnegative integer), or -1 if an
+ *		error occurred (in which case, *errno* is set appropriately).
+ *
+ * BPF_TASK_FD_QUERY
+ *	Description
+ *		Obtain information about eBPF programs associated with the
+ *		target process identified by *pid* and *fd*.
+ *
+ *		If the *pid* and *fd* are associated with a tracepoint, kprobe
+ *		or uprobe perf event, then the *prog_id* and *fd_type* will
+ *		be populated with the eBPF program id and file descriptor type
+ *		of type **bpf_task_fd_type**. If associated with a kprobe or
+ *		uprobe, the  *probe_offset* and *probe_addr* will also be
+ *		populated. Optionally, if *buf* is provided, then up to
+ *		*buf_len* bytes of *buf* will be populated with the name of
+ *		the tracepoint, kprobe or uprobe.
+ *
+ *		The resulting *prog_id* may be introspected in deeper detail
+ *		using **BPF_PROG_GET_FD_BY_ID** and **BPF_OBJ_GET_INFO_BY_FD**.
+ *
+ *	Return
+ *		Returns zero on success. On error, -1 is returned and *errno*
+ *		is set appropriately.
+ *
+ * BPF_MAP_LOOKUP_AND_DELETE_ELEM
+ *	Description
+ *		Look up an element with the given *key* in the map referred to
+ *		by the file descriptor *fd*, and if found, delete the element.
+ *
+ *		The **BPF_MAP_TYPE_QUEUE** and **BPF_MAP_TYPE_STACK** map types
+ *		implement this command as a "pop" operation, deleting the top
+ *		element rather than one corresponding to *key*.
+ *		The *key* and *key_len* parameters should be zeroed when
+ *		issuing this operation for these map types.
+ *
+ *		This command is only valid for the following map types:
+ *		* **BPF_MAP_TYPE_QUEUE**
+ *		* **BPF_MAP_TYPE_STACK**
+ *
+ *	Return
+ *		Returns zero on success. On error, -1 is returned and *errno*
+ *		is set appropriately.
+ *
+ * BPF_MAP_FREEZE
+ *	Description
+ *		Freeze the permissions of the specified map.
+ *
+ *		Write permissions may be frozen by passing zero *flags*.
+ *		Upon success, no future syscall invocations may alter the
+ *		map state of *map_fd*. Write operations from eBPF programs
+ *		are still possible for a frozen map.
+ *
+ *		Not supported for maps of type **BPF_MAP_TYPE_STRUCT_OPS**.
+ *
+ *	Return
+ *		Returns zero on success. On error, -1 is returned and *errno*
+ *		is set appropriately.
+ *
+ * BPF_BTF_GET_NEXT_ID
+ *	Description
+ *		Fetch the next BPF Type Format (BTF) object currently loaded
+ *		into the kernel.
+ *
+ *		Looks for the BTF object with an id greater than *start_id*
+ *		and updates *next_id* on success. If no other BTF objects
+ *		remain with ids higher than *start_id*, returns -1 and sets
+ *		*errno* to **ENOENT**.
+ *
+ *	Return
+ *		Returns zero on success. On error, or when no id remains, -1
+ *		is returned and *errno* is set appropriately.
+ *
+ * BPF_MAP_LOOKUP_BATCH
+ *	Description
+ *		Iterate and fetch multiple elements in a map.
+ *
+ *		Two opaque values are used to manage batch operations,
+ *		*in_batch* and *out_batch*. Initially, *in_batch* must be set
+ *		to NULL to begin the batched operation. After each subsequent
+ *		**BPF_MAP_LOOKUP_BATCH**, the caller should pass the resultant
+ *		*out_batch* as the *in_batch* for the next operation to
+ *		continue iteration from the current point.
+ *
+ *		The *keys* and *values* are output parameters which must point
+ *		to memory large enough to hold *count* items based on the key
+ *		and value size of the map *map_fd*. The *keys* buffer must be
+ *		of *key_size* * *count*. The *values* buffer must be of
+ *		*value_size* * *count*.
+ *
+ *		The *elem_flags* argument may be specified as one of the
+ *		following:
+ *
+ *		**BPF_F_LOCK**
+ *			Look up the value of a spin-locked map without
+ *			returning the lock. This must be specified if the
+ *			elements contain a spinlock.
+ *
+ *		On success, *count* elements from the map are copied into the
+ *		user buffer, with the keys copied into *keys* and the values
+ *		copied into the corresponding indices in *values*.
+ *
+ *		If an error is returned and *errno* is not **EFAULT**, *count*
+ *		is set to the number of successfully processed elements.
+ *
+ *	Return
+ *		Returns zero on success. On error, -1 is returned and *errno*
+ *		is set appropriately.
+ *
+ *		May set *errno* to **ENOSPC** to indicate that *keys* or
+ *		*values* is too small to dump an entire bucket during
+ *		iteration of a hash-based map type.
+ *
+ * BPF_MAP_LOOKUP_AND_DELETE_BATCH
+ *	Description
+ *		Iterate and delete all elements in a map.
+ *
+ *		This operation has the same behavior as
+ *		**BPF_MAP_LOOKUP_BATCH** with two exceptions:
+ *
+ *		* Every element that is successfully returned is also deleted
+ *		  from the map. This is at least *count* elements. Note that
+ *		  *count* is both an input and an output parameter.
+ *		* Upon returning with *errno* set to **EFAULT**, up to
+ *		  *count* elements may be deleted without returning the keys
+ *		  and values of the deleted elements.
+ *
+ *	Return
+ *		Returns zero on success. On error, -1 is returned and *errno*
+ *		is set appropriately.
+ *
+ * BPF_MAP_UPDATE_BATCH
+ *	Description
+ *		Update multiple elements in a map by *key*.
+ *
+ *		The *keys* and *values* are input parameters which must point
+ *		to memory large enough to hold *count* items based on the key
+ *		and value size of the map *map_fd*. The *keys* buffer must be
+ *		of *key_size* * *count*. The *values* buffer must be of
+ *		*value_size* * *count*.
+ *
+ *		Each element specified in *keys* is sequentially updated to the
+ *		value in the corresponding index in *values*. The *in_batch*
+ *		and *out_batch* parameters are ignored and should be zeroed.
+ *
+ *		The *elem_flags* argument should be specified as one of the
+ *		following:
+ *
+ *		**BPF_ANY**
+ *			Create new elements or update a existing elements.
+ *		**BPF_NOEXIST**
+ *			Create new elements only if they do not exist.
+ *		**BPF_EXIST**
+ *			Update existing elements.
+ *		**BPF_F_LOCK**
+ *			Update spin_lock-ed map elements. This must be
+ *			specified if the map value contains a spinlock.
+ *
+ *		On success, *count* elements from the map are updated.
+ *
+ *		If an error is returned and *errno* is not **EFAULT**, *count*
+ *		is set to the number of successfully processed elements.
+ *
+ *	Return
+ *		Returns zero on success. On error, -1 is returned and *errno*
+ *		is set appropriately.
+ *
+ *		May set *errno* to **EINVAL**, **EPERM**, **ENOMEM**, or
+ *		**E2BIG**. **E2BIG** indicates that the number of elements in
+ *		the map reached the *max_entries* limit specified at map
+ *		creation time.
+ *
+ *		May set *errno* to one of the following error codes under
+ *		specific circumstances:
+ *
+ *		**EEXIST**
+ *			If *flags* specifies **BPF_NOEXIST** and the element
+ *			with *key* already exists in the map.
+ *		**ENOENT**
+ *			If *flags* specifies **BPF_EXIST** and the element with
+ *			*key* does not exist in the map.
+ *
+ * BPF_MAP_DELETE_BATCH
+ *	Description
+ *		Delete multiple elements in a map by *key*.
+ *
+ *		The *keys* parameter is an input parameter which must point
+ *		to memory large enough to hold *count* items based on the key
+ *		size of the map *map_fd*, that is, *key_size* * *count*.
+ *
+ *		Each element specified in *keys* is sequentially deleted. The
+ *		*in_batch*, *out_batch*, and *values* parameters are ignored
+ *		and should be zeroed.
+ *
+ *		The *elem_flags* argument may be specified as one of the
+ *		following:
+ *
+ *		**BPF_F_LOCK**
+ *			Look up the value of a spin-locked map without
+ *			returning the lock. This must be specified if the
+ *			elements contain a spinlock.
+ *
+ *		On success, *count* elements from the map are updated.
+ *
+ *		If an error is returned and *errno* is not **EFAULT**, *count*
+ *		is set to the number of successfully processed elements. If
+ *		*errno* is **EFAULT**, up to *count* elements may be been
+ *		deleted.
+ *
+ *	Return
+ *		Returns zero on success. On error, -1 is returned and *errno*
+ *		is set appropriately.
+ *
+ * BPF_LINK_CREATE
+ *	Description
+ *		Attach an eBPF program to a *target_fd* at the specified
+ *		*attach_type* hook and return a file descriptor handle for
+ *		managing the link.
+ *
+ *	Return
+ *		A new file descriptor (a nonnegative integer), or -1 if an
+ *		error occurred (in which case, *errno* is set appropriately).
+ *
+ * BPF_LINK_UPDATE
+ *	Description
+ *		Update the eBPF program in the specified *link_fd* to
+ *		*new_prog_fd*.
+ *
+ *	Return
+ *		Returns zero on success. On error, -1 is returned and *errno*
+ *		is set appropriately.
+ *
+ * BPF_LINK_GET_FD_BY_ID
+ *	Description
+ *		Open a file descriptor for the eBPF Link corresponding to
+ *		*link_id*.
+ *
+ *	Return
+ *		A new file descriptor (a nonnegative integer), or -1 if an
+ *		error occurred (in which case, *errno* is set appropriately).
+ *
+ * BPF_LINK_GET_NEXT_ID
+ *	Description
+ *		Fetch the next eBPF link currently loaded into the kernel.
+ *
+ *		Looks for the eBPF link with an id greater than *start_id*
+ *		and updates *next_id* on success. If no other eBPF links
+ *		remain with ids higher than *start_id*, returns -1 and sets
+ *		*errno* to **ENOENT**.
+ *
+ *	Return
+ *		Returns zero on success. On error, or when no id remains, -1
+ *		is returned and *errno* is set appropriately.
+ *
+ * BPF_ENABLE_STATS
+ *	Description
+ *		Enable eBPF runtime statistics gathering.
+ *
+ *		Runtime statistics gathering for the eBPF runtime is disabled
+ *		by default to minimize the corresponding performance overhead.
+ *		This command enables statistics globally.
+ *
+ *		Multiple programs may independently enable statistics.
+ *		After gathering the desired statistics, eBPF runtime statistics
+ *		may be disabled again by calling **close**\ (2) for the file
+ *		descriptor returned by this function. Statistics will only be
+ *		disabled system-wide when all outstanding file descriptors
+ *		returned by prior calls for this subcommand are closed.
+ *
+ *	Return
+ *		A new file descriptor (a nonnegative integer), or -1 if an
+ *		error occurred (in which case, *errno* is set appropriately).
+ *
+ * BPF_ITER_CREATE
+ *	Description
+ *		Create an iterator on top of the specified *link_fd* (as
+ *		previously created using **BPF_LINK_CREATE**) and return a
+ *		file descriptor that can be used to trigger the iteration.
+ *
+ *		If the resulting file descriptor is pinned to the filesystem
+ *		using  **BPF_OBJ_PIN**, then subsequent **read**\ (2) syscalls
+ *		for that path will trigger the iterator to read kernel state
+ *		using the eBPF program attached to *link_fd*.
+ *
+ *	Return
+ *		A new file descriptor (a nonnegative integer), or -1 if an
+ *		error occurred (in which case, *errno* is set appropriately).
+ *
+ * BPF_LINK_DETACH
+ *	Description
+ *		Forcefully detach the specified *link_fd* from its
+ *		corresponding attachment point.
+ *
+ *	Return
+ *		Returns zero on success. On error, -1 is returned and *errno*
+ *		is set appropriately.
+ *
+ * BPF_PROG_BIND_MAP
+ *	Description
+ *		Bind a map to the lifetime of an eBPF program.
+ *
+ *		The map identified by *map_fd* is bound to the program
+ *		identified by *prog_fd* and only released when *prog_fd* is
+ *		released. This may be used in cases where metadata should be
+ *		associated with a program which otherwise does not contain any
+ *		references to the map (for example, embedded in the eBPF
+ *		program instructions).
+ *
+ *	Return
+ *		Returns zero on success. On error, -1 is returned and *errno*
+ *		is set appropriately.
+ *
+ * NOTES
+ *	eBPF objects (maps and programs) can be shared between processes.
+ *
+ *	* After **fork**\ (2), the child inherits file descriptors
+ *	  referring to the same eBPF objects.
+ *	* File descriptors referring to eBPF objects can be transferred over
+ *	  **unix**\ (7) domain sockets.
+ *	* File descriptors referring to eBPF objects can be duplicated in the
+ *	  usual way, using **dup**\ (2) and similar calls.
+ *	* File descriptors referring to eBPF objects can be pinned to the
+ *	  filesystem using the **BPF_OBJ_PIN** command of **bpf**\ (2).
+ *
+ *	An eBPF object is deallocated only after all file descriptors referring
+ *	to the object have been closed and no references remain pinned to the
+ *	filesystem or attached (for example, bound to a program or device).
+ */
 enum bpf_cmd {
 	BPF_MAP_CREATE,
 	BPF_MAP_LOOKUP_ELEM,
@@ -729,7 +1439,7 @@ union bpf_attr {
  * parsed and used to produce a manual page. The workflow is the following,
  * and requires the rst2man utility:
  *
- *     $ ./scripts/bpf_helpers_doc.py \
+ *     $ ./scripts/bpf_doc.py \
  *             --filename include/uapi/linux/bpf.h > /tmp/bpf-helpers.rst
  *     $ rst2man /tmp/bpf-helpers.rst > /tmp/bpf-helpers.7
  *     $ man /tmp/bpf-helpers.7

tools/lib/bpf/Makefile

@@ -158,7 +158,7 @@ $(BPF_IN_STATIC): force $(BPF_HELPER_DEFS)
 	$(Q)$(MAKE) $(build)=libbpf OUTPUT=$(STATIC_OBJDIR)
 
 $(BPF_HELPER_DEFS): $(srctree)/tools/include/uapi/linux/bpf.h
-	$(QUIET_GEN)$(srctree)/scripts/bpf_helpers_doc.py --header \
+	$(QUIET_GEN)$(srctree)/scripts/bpf_doc.py --header \
 		--file $(srctree)/tools/include/uapi/linux/bpf.h > $(BPF_HELPER_DEFS)
 
 $(OUTPUT)libbpf.so: $(OUTPUT)libbpf.so.$(LIBBPF_VERSION)

tools/perf/MANIFEST

@@ -20,4 +20,4 @@ tools/lib/bitmap.c
 tools/lib/str_error_r.c
 tools/lib/vsprintf.c
 tools/lib/zalloc.c
-scripts/bpf_helpers_doc.py
+scripts/bpf_doc.py

tools/testing/selftests/bpf/.gitignore

 # SPDX-License-Identifier: GPL-2.0-only
+bpf-helpers*
+bpf-syscall*
 test_verifier
 test_maps
 test_lru_map

tools/testing/selftests/bpf/Makefile

@@ -68,6 +68,7 @@ TEST_PROGS := test_kmod.sh \
 	test_bpftool_build.sh \
 	test_bpftool.sh \
 	test_bpftool_metadata.sh \
+	test_docs_build.sh \
 	test_xsk.sh
 
 TEST_PROGS_EXTENDED := with_addr.sh \
@@ -103,6 +104,7 @@ override define CLEAN
 	$(call msg,CLEAN)
 	$(Q)$(RM) -r $(TEST_GEN_PROGS) $(TEST_GEN_PROGS_EXTENDED) $(TEST_GEN_FILES) $(EXTRA_CLEAN)
 	$(Q)$(MAKE) -C bpf_testmod clean
+	$(Q)$(MAKE) docs-clean
 endef
 
 include ../lib.mk
@@ -180,6 +182,7 @@ $(OUTPUT)/runqslower: $(BPFOBJ) | $(DEFAULT_BPFTOOL)
 		    cp $(SCRATCH_DIR)/runqslower $@
 
 $(TEST_GEN_PROGS) $(TEST_GEN_PROGS_EXTENDED): $(OUTPUT)/test_stub.o $(BPFOBJ)
+$(TEST_GEN_FILES): docs
 
 $(OUTPUT)/test_dev_cgroup: cgroup_helpers.c
 $(OUTPUT)/test_skb_cgroup_id_user: cgroup_helpers.c
@@ -200,11 +203,16 @@ $(DEFAULT_BPFTOOL): $(wildcard $(BPFTOOLDIR)/*.[ch] $(BPFTOOLDIR)/Makefile)    \
 		    CC=$(HOSTCC) LD=$(HOSTLD)				       \
 		    OUTPUT=$(HOST_BUILD_DIR)/bpftool/			       \
 		    prefix= DESTDIR=$(HOST_SCRATCH_DIR)/ install
-	$(Q)mkdir -p $(BUILD_DIR)/bpftool/Documentation
+
+docs:
 	$(Q)RST2MAN_OPTS="--exit-status=1" $(MAKE) $(submake_extras)	\
-		    -C $(BPFTOOLDIR)/Documentation			       \
-		    OUTPUT=$(BUILD_DIR)/bpftool/Documentation/		       \
-		    prefix= DESTDIR=$(SCRATCH_DIR)/ install
+	            -f Makefile.docs					\
+	            prefix= OUTPUT=$(OUTPUT)/ DESTDIR=$(OUTPUT)/ $@
+
+docs-clean:
+	$(Q)$(MAKE) $(submake_extras)					\
+	            -f Makefile.docs					\
+	            prefix= OUTPUT=$(OUTPUT)/ DESTDIR=$(OUTPUT)/ $@
 
 $(BPFOBJ): $(wildcard $(BPFDIR)/*.[ch] $(BPFDIR)/Makefile)		       \
 	   ../../../include/uapi/linux/bpf.h                                   \
@@ -477,3 +485,5 @@ EXTRA_CLEAN := $(TEST_CUSTOM_PROGS) $(SCRATCH_DIR) $(HOST_SCRATCH_DIR)	\
 	prog_tests/tests.h map_tests/tests.h verifier/tests.h		\
 	feature								\
 	$(addprefix $(OUTPUT)/,*.o *.skel.h no_alu32 bpf_gcc bpf_testmod.ko)
+
+.PHONY: docs docs-clean

tools/testing/selftests/bpf/Makefile.docs

+# SPDX-License-Identifier: GPL-2.0-only
+
+include ../../../scripts/Makefile.include
+include ../../../scripts/utilities.mak
+
+INSTALL ?= install
+RM ?= rm -f
+RMDIR ?= rmdir --ignore-fail-on-non-empty
+
+ifeq ($(V),1)
+  Q =
+else
+  Q = @
+endif
+
+prefix ?= /usr/local
+mandir ?= $(prefix)/man
+man2dir = $(mandir)/man2
+man7dir = $(mandir)/man7
+
+SYSCALL_RST = bpf-syscall.rst
+MAN2_RST = $(SYSCALL_RST)
+
+HELPERS_RST = bpf-helpers.rst
+MAN7_RST = $(HELPERS_RST)
+
+_DOC_MAN2 = $(patsubst %.rst,%.2,$(MAN2_RST))
+DOC_MAN2 = $(addprefix $(OUTPUT),$(_DOC_MAN2))
+
+_DOC_MAN7 = $(patsubst %.rst,%.7,$(MAN7_RST))
+DOC_MAN7 = $(addprefix $(OUTPUT),$(_DOC_MAN7))
+
+DOCTARGETS := helpers syscall
+
+docs: $(DOCTARGETS)
+syscall: man2
+helpers: man7
+man2: $(DOC_MAN2)
+man7: $(DOC_MAN7)
+
+RST2MAN_DEP := $(shell command -v rst2man 2>/dev/null)
+
+# Configure make rules for the man page bpf-$1.$2.
+# $1 - target for scripts/bpf_doc.py
+# $2 - man page section to generate the troff file
+define DOCS_RULES =
+$(OUTPUT)bpf-$1.rst: ../../../../include/uapi/linux/bpf.h
+	$$(QUIET_GEN)../../../../scripts/bpf_doc.py $1 \
+		--filename $$< > $$@
+
+$(OUTPUT)%.$2: $(OUTPUT)%.rst
+ifndef RST2MAN_DEP
+	$$(error "rst2man not found, but required to generate man pages")
+endif
+	$$(QUIET_GEN)rst2man $$< > $$@
+
+docs-clean-$1:
+	$$(call QUIET_CLEAN, eBPF_$1-manpage)
+	$(Q)$(RM) $$(DOC_MAN$2) $(OUTPUT)bpf-$1.rst
+
+docs-install-$1: docs
+	$$(call QUIET_INSTALL, eBPF_$1-manpage)
+	$(Q)$(INSTALL) -d -m 755 $(DESTDIR)$$(man$2dir)
+	$(Q)$(INSTALL) -m 644 $$(DOC_MAN$2) $(DESTDIR)$$(man$2dir)
+
+docs-uninstall-$1:
+	$$(call QUIET_UNINST, eBPF_$1-manpage)
+	$(Q)$(RM) $$(addprefix $(DESTDIR)$$(man$2dir)/,$$(_DOC_MAN$2))
+	$(Q)$(RMDIR) $(DESTDIR)$$(man$2dir)
+
+.PHONY: $1 docs-clean-$1 docs-install-$1 docs-uninstall-$1
+endef
+
+# Create the make targets to generate manual pages by name and section
+$(eval $(call DOCS_RULES,helpers,7))
+$(eval $(call DOCS_RULES,syscall,2))
+
+docs-clean: $(foreach doctarget,$(DOCTARGETS), docs-clean-$(doctarget))
+docs-install: $(foreach doctarget,$(DOCTARGETS), docs-install-$(doctarget))
+docs-uninstall: $(foreach doctarget,$(DOCTARGETS), docs-uninstall-$(doctarget))
+
+.PHONY: docs docs-clean docs-install docs-uninstall man2 man7

tools/testing/selftests/bpf/test_bpftool_build.sh

@@ -85,23 +85,6 @@ make_with_tmpdir() {
 	echo
 }
 
-make_doc_and_clean() {
-	echo -e "\$PWD:    $PWD"
-	echo -e "command: make -s $* doc >/dev/null"
-	RST2MAN_OPTS="--exit-status=1" make $J -s $* doc
-	if [ $? -ne 0 ] ; then
-		ERROR=1
-		printf "FAILURE: Errors or warnings when building documentation\n"
-	fi
-	(
-		if [ $# -ge 1 ] ; then
-			cd ${@: -1}
-		fi
-		make -s doc-clean
-	)
-	echo
-}
-
 echo "Trying to build bpftool"
 echo -e "... through kbuild\n"
 
@@ -162,7 +145,3 @@ make_and_clean
 make_with_tmpdir OUTPUT
 
 make_with_tmpdir O
-
-echo -e "Checking documentation build\n"
-# From tools/bpf/bpftool
-make_doc_and_clean

tools/testing/selftests/bpf/test_doc_build.sh

+#!/bin/bash
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+
+# Assume script is located under tools/testing/selftests/bpf/. We want to start
+# build attempts from the top of kernel repository.
+SCRIPT_REL_PATH=$(realpath --relative-to=$PWD $0)
+SCRIPT_REL_DIR=$(dirname $SCRIPT_REL_PATH)
+KDIR_ROOT_DIR=$(realpath $PWD/$SCRIPT_REL_DIR/../../../../)
+cd $KDIR_ROOT_DIR
+
+for tgt in docs docs-clean; do
+	make -s -C $PWD/$SCRIPT_REL_DIR $tgt;
+done