mirror of https://gitee.com/openkylin/linux.git
bpf: add script and prepare bpf.h for new helpers documentation
Remove previous "overview" of eBPF helpers from user bpf.h header.
Replace it by a comment explaining how to process the new documentation
(to come in following patches) with a Python script to produce RST, then
man page documentation.
Also add the aforementioned Python script under scripts/. It is used to
process include/uapi/linux/bpf.h and to extract helper descriptions, to
turn it into a RST document that can further be processed with rst2man
to produce a man page. The script takes one "--filename <path/to/file>"
option. If the script is launched from scripts/ in the kernel root
directory, it should be able to find the location of the header to
parse, and "--filename <path/to/file>" is then optional. If it cannot
find the file, then the option becomes mandatory. RST-formatted
documentation is printed to standard output.
Typical workflow for producing the final man page would be:
$ ./scripts/bpf_helpers_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
Note that the tool kernel-doc cannot be used to document eBPF helpers,
whose signatures are not available directly in the header files
(pre-processor directives are used to produce them at the beginning of
the compilation process).
v4:
- Also remove overviews for newly added bpf_xdp_adjust_tail() and
bpf_skb_get_xfrm_state().
- Remove vague statement about what helpers are restricted to GPL
programs in "LICENSE" section for man page footer.
- Replace license boilerplate with SPDX tag for Python script.
v3:
- Change license for man page.
- Remove "for safety reasons" from man page header text.
- Change "packets metadata" to "packets" in man page header text.
- Move and fix comment on helpers introducing no overhead.
- Remove "NOTES" section from man page footer.
- Add "LICENSE" section to man page footer.
- Edit description of file include/uapi/linux/bpf.h in man page footer.
Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This commit is contained in:
Quentin Monnet
Daniel Borkmann
parent
3f13de6d6f
commit
56a092c895
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@ -377,412 +377,22 @@ union bpf_attr {
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};
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};
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} __attribute__((aligned(8)));
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} __attribute__((aligned(8)));
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/* BPF helper function descriptions:
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/* The description below is an attempt at providing documentation to eBPF
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* developers about the multiple available eBPF helper functions. It can be
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* parsed and used to produce a manual page. The workflow is the following,
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* and requires the rst2man utility:
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*
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*
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* void *bpf_map_lookup_elem(&map, &key)
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* $ ./scripts/bpf_helpers_doc.py \
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* Return: Map value or NULL
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* --filename include/uapi/linux/bpf.h > /tmp/bpf-helpers.rst
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* $ rst2man /tmp/bpf-helpers.rst > /tmp/bpf-helpers.7
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* $ man /tmp/bpf-helpers.7
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*
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*
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* int bpf_map_update_elem(&map, &key, &value, flags)
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* Note that in order to produce this external documentation, some RST
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* Return: 0 on success or negative error
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* formatting is used in the descriptions to get "bold" and "italics" in
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* manual pages. Also note that the few trailing white spaces are
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* intentional, removing them would break paragraphs for rst2man.
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*
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*
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* int bpf_map_delete_elem(&map, &key)
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* Start of BPF helper function descriptions:
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* Return: 0 on success or negative error
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*
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* int bpf_probe_read(void *dst, int size, void *src)
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* Return: 0 on success or negative error
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*
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* u64 bpf_ktime_get_ns(void)
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* Return: current ktime
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*
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* int bpf_trace_printk(const char *fmt, int fmt_size, ...)
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* Return: length of buffer written or negative error
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*
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* u32 bpf_prandom_u32(void)
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* Return: random value
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*
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* u32 bpf_raw_smp_processor_id(void)
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* Return: SMP processor ID
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*
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* int bpf_skb_store_bytes(skb, offset, from, len, flags)
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* store bytes into packet
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* @skb: pointer to skb
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* @offset: offset within packet from skb->mac_header
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* @from: pointer where to copy bytes from
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* @len: number of bytes to store into packet
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* @flags: bit 0 - if true, recompute skb->csum
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* other bits - reserved
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* Return: 0 on success or negative error
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*
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* int bpf_l3_csum_replace(skb, offset, from, to, flags)
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* recompute IP checksum
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* @skb: pointer to skb
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* @offset: offset within packet where IP checksum is located
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* @from: old value of header field
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* @to: new value of header field
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* @flags: bits 0-3 - size of header field
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* other bits - reserved
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* Return: 0 on success or negative error
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*
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* int bpf_l4_csum_replace(skb, offset, from, to, flags)
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* recompute TCP/UDP checksum
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* @skb: pointer to skb
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* @offset: offset within packet where TCP/UDP checksum is located
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* @from: old value of header field
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* @to: new value of header field
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* @flags: bits 0-3 - size of header field
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* bit 4 - is pseudo header
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* other bits - reserved
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* Return: 0 on success or negative error
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*
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* int bpf_tail_call(ctx, prog_array_map, index)
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* jump into another BPF program
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* @ctx: context pointer passed to next program
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* @prog_array_map: pointer to map which type is BPF_MAP_TYPE_PROG_ARRAY
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* @index: 32-bit index inside array that selects specific program to run
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* Return: 0 on success or negative error
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*
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* int bpf_clone_redirect(skb, ifindex, flags)
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* redirect to another netdev
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* @skb: pointer to skb
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* @ifindex: ifindex of the net device
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* @flags: bit 0 - if set, redirect to ingress instead of egress
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* other bits - reserved
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* Return: 0 on success or negative error
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*
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* u64 bpf_get_current_pid_tgid(void)
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* Return: current->tgid << 32 | current->pid
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*
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* u64 bpf_get_current_uid_gid(void)
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* Return: current_gid << 32 | current_uid
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*
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* int bpf_get_current_comm(char *buf, int size_of_buf)
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* stores current->comm into buf
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* Return: 0 on success or negative error
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*
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* u32 bpf_get_cgroup_classid(skb)
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* retrieve a proc's classid
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* @skb: pointer to skb
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* Return: classid if != 0
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*
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* int bpf_skb_vlan_push(skb, vlan_proto, vlan_tci)
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* Return: 0 on success or negative error
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*
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* int bpf_skb_vlan_pop(skb)
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* Return: 0 on success or negative error
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*
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* int bpf_skb_get_tunnel_key(skb, key, size, flags)
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* int bpf_skb_set_tunnel_key(skb, key, size, flags)
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* retrieve or populate tunnel metadata
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* @skb: pointer to skb
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* @key: pointer to 'struct bpf_tunnel_key'
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* @size: size of 'struct bpf_tunnel_key'
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* @flags: room for future extensions
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* Return: 0 on success or negative error
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*
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* u64 bpf_perf_event_read(map, flags)
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* read perf event counter value
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* @map: pointer to perf_event_array map
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* @flags: index of event in the map or bitmask flags
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* Return: value of perf event counter read or error code
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*
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* int bpf_redirect(ifindex, flags)
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* redirect to another netdev
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* @ifindex: ifindex of the net device
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* @flags:
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* cls_bpf:
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* bit 0 - if set, redirect to ingress instead of egress
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* other bits - reserved
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* xdp_bpf:
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* all bits - reserved
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* Return: cls_bpf: TC_ACT_REDIRECT on success or TC_ACT_SHOT on error
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* xdp_bfp: XDP_REDIRECT on success or XDP_ABORT on error
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* int bpf_redirect_map(map, key, flags)
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* redirect to endpoint in map
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* @map: pointer to dev map
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* @key: index in map to lookup
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* @flags: --
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* Return: XDP_REDIRECT on success or XDP_ABORT on error
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*
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* u32 bpf_get_route_realm(skb)
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* retrieve a dst's tclassid
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* @skb: pointer to skb
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* Return: realm if != 0
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*
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* int bpf_perf_event_output(ctx, map, flags, data, size)
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* output perf raw sample
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* @ctx: struct pt_regs*
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* @map: pointer to perf_event_array map
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* @flags: index of event in the map or bitmask flags
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* @data: data on stack to be output as raw data
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* @size: size of data
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* Return: 0 on success or negative error
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*
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* int bpf_get_stackid(ctx, map, flags)
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* walk user or kernel stack and return id
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* @ctx: struct pt_regs*
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* @map: pointer to stack_trace map
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* @flags: bits 0-7 - numer of stack frames to skip
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* bit 8 - collect user stack instead of kernel
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* bit 9 - compare stacks by hash only
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* bit 10 - if two different stacks hash into the same stackid
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* discard old
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* other bits - reserved
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* Return: >= 0 stackid on success or negative error
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*
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* s64 bpf_csum_diff(from, from_size, to, to_size, seed)
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* calculate csum diff
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* @from: raw from buffer
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* @from_size: length of from buffer
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* @to: raw to buffer
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* @to_size: length of to buffer
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* @seed: optional seed
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* Return: csum result or negative error code
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*
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* int bpf_skb_get_tunnel_opt(skb, opt, size)
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* retrieve tunnel options metadata
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* @skb: pointer to skb
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* @opt: pointer to raw tunnel option data
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* @size: size of @opt
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* Return: option size
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*
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* int bpf_skb_set_tunnel_opt(skb, opt, size)
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* populate tunnel options metadata
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* @skb: pointer to skb
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* @opt: pointer to raw tunnel option data
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* @size: size of @opt
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* Return: 0 on success or negative error
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*
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* int bpf_skb_change_proto(skb, proto, flags)
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* Change protocol of the skb. Currently supported is v4 -> v6,
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* v6 -> v4 transitions. The helper will also resize the skb. eBPF
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* program is expected to fill the new headers via skb_store_bytes
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* and lX_csum_replace.
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* @skb: pointer to skb
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* @proto: new skb->protocol type
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* @flags: reserved
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* Return: 0 on success or negative error
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*
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* int bpf_skb_change_type(skb, type)
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* Change packet type of skb.
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* @skb: pointer to skb
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* @type: new skb->pkt_type type
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* Return: 0 on success or negative error
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*
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* int bpf_skb_under_cgroup(skb, map, index)
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* Check cgroup2 membership of skb
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* @skb: pointer to skb
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* @map: pointer to bpf_map in BPF_MAP_TYPE_CGROUP_ARRAY type
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* @index: index of the cgroup in the bpf_map
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* Return:
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* == 0 skb failed the cgroup2 descendant test
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* == 1 skb succeeded the cgroup2 descendant test
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* < 0 error
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*
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* u32 bpf_get_hash_recalc(skb)
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* Retrieve and possibly recalculate skb->hash.
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* @skb: pointer to skb
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* Return: hash
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*
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* u64 bpf_get_current_task(void)
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* Returns current task_struct
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* Return: current
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*
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* int bpf_probe_write_user(void *dst, void *src, int len)
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* safely attempt to write to a location
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* @dst: destination address in userspace
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* @src: source address on stack
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* @len: number of bytes to copy
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* Return: 0 on success or negative error
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*
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* int bpf_current_task_under_cgroup(map, index)
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* Check cgroup2 membership of current task
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* @map: pointer to bpf_map in BPF_MAP_TYPE_CGROUP_ARRAY type
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* @index: index of the cgroup in the bpf_map
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* Return:
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* == 0 current failed the cgroup2 descendant test
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* == 1 current succeeded the cgroup2 descendant test
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* < 0 error
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*
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* int bpf_skb_change_tail(skb, len, flags)
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* The helper will resize the skb to the given new size, to be used f.e.
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* with control messages.
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* @skb: pointer to skb
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* @len: new skb length
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* @flags: reserved
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* Return: 0 on success or negative error
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*
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* int bpf_skb_pull_data(skb, len)
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* The helper will pull in non-linear data in case the skb is non-linear
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* and not all of len are part of the linear section. Only needed for
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* read/write with direct packet access.
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* @skb: pointer to skb
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* @len: len to make read/writeable
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* Return: 0 on success or negative error
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*
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* s64 bpf_csum_update(skb, csum)
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* Adds csum into skb->csum in case of CHECKSUM_COMPLETE.
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* @skb: pointer to skb
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* @csum: csum to add
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* Return: csum on success or negative error
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*
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* void bpf_set_hash_invalid(skb)
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* Invalidate current skb->hash.
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* @skb: pointer to skb
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*
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* int bpf_get_numa_node_id()
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* Return: Id of current NUMA node.
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*
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* int bpf_skb_change_head()
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* Grows headroom of skb and adjusts MAC header offset accordingly.
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* Will extends/reallocae as required automatically.
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* May change skb data pointer and will thus invalidate any check
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* performed for direct packet access.
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* @skb: pointer to skb
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* @len: length of header to be pushed in front
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* @flags: Flags (unused for now)
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* Return: 0 on success or negative error
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*
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* int bpf_xdp_adjust_head(xdp_md, delta)
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* Adjust the xdp_md.data by delta
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* @xdp_md: pointer to xdp_md
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* @delta: An positive/negative integer to be added to xdp_md.data
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* Return: 0 on success or negative on error
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*
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* int bpf_probe_read_str(void *dst, int size, const void *unsafe_ptr)
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* Copy a NUL terminated string from unsafe address. In case the string
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* length is smaller than size, the target is not padded with further NUL
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* bytes. In case the string length is larger than size, just count-1
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* bytes are copied and the last byte is set to NUL.
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* @dst: destination address
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* @size: maximum number of bytes to copy, including the trailing NUL
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* @unsafe_ptr: unsafe address
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* Return:
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* > 0 length of the string including the trailing NUL on success
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* < 0 error
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*
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* u64 bpf_get_socket_cookie(skb)
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* Get the cookie for the socket stored inside sk_buff.
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* @skb: pointer to skb
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* Return: 8 Bytes non-decreasing number on success or 0 if the socket
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* field is missing inside sk_buff
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*
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* u32 bpf_get_socket_uid(skb)
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* Get the owner uid of the socket stored inside sk_buff.
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* @skb: pointer to skb
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* Return: uid of the socket owner on success or overflowuid if failed.
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*
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* u32 bpf_set_hash(skb, hash)
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* Set full skb->hash.
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* @skb: pointer to skb
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* @hash: hash to set
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*
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* int bpf_setsockopt(bpf_socket, level, optname, optval, optlen)
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* Calls setsockopt. Not all opts are available, only those with
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* integer optvals plus TCP_CONGESTION.
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* Supported levels: SOL_SOCKET and IPPROTO_TCP
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* @bpf_socket: pointer to bpf_socket
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* @level: SOL_SOCKET or IPPROTO_TCP
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* @optname: option name
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* @optval: pointer to option value
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* @optlen: length of optval in bytes
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* Return: 0 or negative error
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*
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|
||||||
* int bpf_getsockopt(bpf_socket, level, optname, optval, optlen)
|
|
||||||
* Calls getsockopt. Not all opts are available.
|
|
||||||
* Supported levels: IPPROTO_TCP
|
|
||||||
* @bpf_socket: pointer to bpf_socket
|
|
||||||
* @level: IPPROTO_TCP
|
|
||||||
* @optname: option name
|
|
||||||
* @optval: pointer to option value
|
|
||||||
* @optlen: length of optval in bytes
|
|
||||||
* Return: 0 or negative error
|
|
||||||
*
|
|
||||||
* int bpf_sock_ops_cb_flags_set(bpf_sock_ops, flags)
|
|
||||||
* Set callback flags for sock_ops
|
|
||||||
* @bpf_sock_ops: pointer to bpf_sock_ops_kern struct
|
|
||||||
* @flags: flags value
|
|
||||||
* Return: 0 for no error
|
|
||||||
* -EINVAL if there is no full tcp socket
|
|
||||||
* bits in flags that are not supported by current kernel
|
|
||||||
*
|
|
||||||
* int bpf_skb_adjust_room(skb, len_diff, mode, flags)
|
|
||||||
* Grow or shrink room in sk_buff.
|
|
||||||
* @skb: pointer to skb
|
|
||||||
* @len_diff: (signed) amount of room to grow/shrink
|
|
||||||
* @mode: operation mode (enum bpf_adj_room_mode)
|
|
||||||
* @flags: reserved for future use
|
|
||||||
* Return: 0 on success or negative error code
|
|
||||||
*
|
|
||||||
* int bpf_sk_redirect_map(map, key, flags)
|
|
||||||
* Redirect skb to a sock in map using key as a lookup key for the
|
|
||||||
* sock in map.
|
|
||||||
* @map: pointer to sockmap
|
|
||||||
* @key: key to lookup sock in map
|
|
||||||
* @flags: reserved for future use
|
|
||||||
* Return: SK_PASS
|
|
||||||
*
|
|
||||||
* int bpf_sock_map_update(skops, map, key, flags)
|
|
||||||
* @skops: pointer to bpf_sock_ops
|
|
||||||
* @map: pointer to sockmap to update
|
|
||||||
* @key: key to insert/update sock in map
|
|
||||||
* @flags: same flags as map update elem
|
|
||||||
*
|
|
||||||
* int bpf_xdp_adjust_meta(xdp_md, delta)
|
|
||||||
* Adjust the xdp_md.data_meta by delta
|
|
||||||
* @xdp_md: pointer to xdp_md
|
|
||||||
* @delta: An positive/negative integer to be added to xdp_md.data_meta
|
|
||||||
* Return: 0 on success or negative on error
|
|
||||||
*
|
|
||||||
* int bpf_perf_event_read_value(map, flags, buf, buf_size)
|
|
||||||
* read perf event counter value and perf event enabled/running time
|
|
||||||
* @map: pointer to perf_event_array map
|
|
||||||
* @flags: index of event in the map or bitmask flags
|
|
||||||
* @buf: buf to fill
|
|
||||||
* @buf_size: size of the buf
|
|
||||||
* Return: 0 on success or negative error code
|
|
||||||
*
|
|
||||||
* int bpf_perf_prog_read_value(ctx, buf, buf_size)
|
|
||||||
* read perf prog attached perf event counter and enabled/running time
|
|
||||||
* @ctx: pointer to ctx
|
|
||||||
* @buf: buf to fill
|
|
||||||
* @buf_size: size of the buf
|
|
||||||
* Return : 0 on success or negative error code
|
|
||||||
*
|
|
||||||
* int bpf_override_return(pt_regs, rc)
|
|
||||||
* @pt_regs: pointer to struct pt_regs
|
|
||||||
* @rc: the return value to set
|
|
||||||
*
|
|
||||||
* int bpf_msg_redirect_map(map, key, flags)
|
|
||||||
* Redirect msg to a sock in map using key as a lookup key for the
|
|
||||||
* sock in map.
|
|
||||||
* @map: pointer to sockmap
|
|
||||||
* @key: key to lookup sock in map
|
|
||||||
* @flags: reserved for future use
|
|
||||||
* Return: SK_PASS
|
|
||||||
*
|
|
||||||
* int bpf_bind(ctx, addr, addr_len)
|
|
||||||
* Bind socket to address. Only binding to IP is supported, no port can be
|
|
||||||
* set in addr.
|
|
||||||
* @ctx: pointer to context of type bpf_sock_addr
|
|
||||||
* @addr: pointer to struct sockaddr to bind socket to
|
|
||||||
* @addr_len: length of sockaddr structure
|
|
||||||
* Return: 0 on success or negative error code
|
|
||||||
*
|
|
||||||
* int bpf_xdp_adjust_tail(xdp_md, delta)
|
|
||||||
* Adjust the xdp_md.data_end by delta. Only shrinking of packet's
|
|
||||||
* size is supported.
|
|
||||||
* @xdp_md: pointer to xdp_md
|
|
||||||
* @delta: A negative integer to be added to xdp_md.data_end
|
|
||||||
* Return: 0 on success or negative on error
|
|
||||||
*
|
|
||||||
* int bpf_skb_get_xfrm_state(skb, index, xfrm_state, size, flags)
|
|
||||||
* retrieve XFRM state
|
|
||||||
* @skb: pointer to skb
|
|
||||||
* @index: index of the xfrm state in the secpath
|
|
||||||
* @key: pointer to 'struct bpf_xfrm_state'
|
|
||||||
* @size: size of 'struct bpf_xfrm_state'
|
|
||||||
* @flags: room for future extensions
|
|
||||||
* Return: 0 on success or negative error
|
|
||||||
*/
|
*/
|
||||||
#define __BPF_FUNC_MAPPER(FN) \
|
#define __BPF_FUNC_MAPPER(FN) \
|
||||||
FN(unspec), \
|
FN(unspec), \
|
||||||
|
|
|
||||||
|
|
@ -0,0 +1,421 @@
|
||||||
|
#!/usr/bin/python3
|
||||||
|
# SPDX-License-Identifier: GPL-2.0-only
|
||||||
|
#
|
||||||
|
# Copyright (C) 2018 Netronome Systems, Inc.
|
||||||
|
|
||||||
|
# In case user attempts to run with Python 2.
|
||||||
|
from __future__ import print_function
|
||||||
|
|
||||||
|
import argparse
|
||||||
|
import re
|
||||||
|
import sys, os
|
||||||
|
|
||||||
|
class NoHelperFound(BaseException):
|
||||||
|
pass
|
||||||
|
|
||||||
|
class ParsingError(BaseException):
|
||||||
|
def __init__(self, line='<line not provided>', reader=None):
|
||||||
|
if reader:
|
||||||
|
BaseException.__init__(self,
|
||||||
|
'Error at file offset %d, parsing line: %s' %
|
||||||
|
(reader.tell(), line))
|
||||||
|
else:
|
||||||
|
BaseException.__init__(self, 'Error parsing line: %s' % line)
|
||||||
|
|
||||||
|
class Helper(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
|
||||||
|
"""
|
||||||
|
def __init__(self, proto='', desc='', ret=''):
|
||||||
|
self.proto = proto
|
||||||
|
self.desc = desc
|
||||||
|
self.ret = ret
|
||||||
|
|
||||||
|
def proto_break_down(self):
|
||||||
|
"""
|
||||||
|
Break down helper function protocol into smaller chunks: return type,
|
||||||
|
name, distincts arguments.
|
||||||
|
"""
|
||||||
|
arg_re = re.compile('^((const )?(struct )?(\w+|...))( (\**)(\w+))?$')
|
||||||
|
res = {}
|
||||||
|
proto_re = re.compile('^(.+) (\**)(\w+)\(((([^,]+)(, )?){1,5})\)$')
|
||||||
|
|
||||||
|
capture = proto_re.match(self.proto)
|
||||||
|
res['ret_type'] = capture.group(1)
|
||||||
|
res['ret_star'] = capture.group(2)
|
||||||
|
res['name'] = capture.group(3)
|
||||||
|
res['args'] = []
|
||||||
|
|
||||||
|
args = capture.group(4).split(', ')
|
||||||
|
for a in args:
|
||||||
|
capture = arg_re.match(a)
|
||||||
|
res['args'].append({
|
||||||
|
'type' : capture.group(1),
|
||||||
|
'star' : capture.group(6),
|
||||||
|
'name' : capture.group(7)
|
||||||
|
})
|
||||||
|
|
||||||
|
return res
|
||||||
|
|
||||||
|
class HeaderParser(object):
|
||||||
|
"""
|
||||||
|
An object used to parse a file in order to extract the documentation of a
|
||||||
|
list of eBPF helper functions. All the helpers that can be retrieved are
|
||||||
|
stored as Helper object, in the self.helpers() array.
|
||||||
|
@filename: name of file to parse, usually include/uapi/linux/bpf.h in the
|
||||||
|
kernel tree
|
||||||
|
"""
|
||||||
|
def __init__(self, filename):
|
||||||
|
self.reader = open(filename, 'r')
|
||||||
|
self.line = ''
|
||||||
|
self.helpers = []
|
||||||
|
|
||||||
|
def parse_helper(self):
|
||||||
|
proto = self.parse_proto()
|
||||||
|
desc = self.parse_desc()
|
||||||
|
ret = self.parse_ret()
|
||||||
|
return Helper(proto=proto, desc=desc, ret=ret)
|
||||||
|
|
||||||
|
def parse_proto(self):
|
||||||
|
# Argument can be of shape:
|
||||||
|
# - "void"
|
||||||
|
# - "type name"
|
||||||
|
# - "type *name"
|
||||||
|
# - Same as above, with "const" and/or "struct" in front of type
|
||||||
|
# - "..." (undefined number of arguments, for bpf_trace_printk())
|
||||||
|
# There is at least one term ("void"), and at most five arguments.
|
||||||
|
p = re.compile('^ \* ((.+) \**\w+\((((const )?(struct )?(\w+|\.\.\.)( \**\w+)?)(, )?){1,5}\))$')
|
||||||
|
capture = p.match(self.line)
|
||||||
|
if not capture:
|
||||||
|
raise NoHelperFound
|
||||||
|
self.line = self.reader.readline()
|
||||||
|
return capture.group(1)
|
||||||
|
|
||||||
|
def parse_desc(self):
|
||||||
|
p = re.compile('^ \* \tDescription$')
|
||||||
|
capture = p.match(self.line)
|
||||||
|
if not capture:
|
||||||
|
# Helper can have empty description and we might be parsing another
|
||||||
|
# attribute: return but do not consume.
|
||||||
|
return ''
|
||||||
|
# Description can be several lines, some of them possibly empty, and it
|
||||||
|
# stops when another subsection title is met.
|
||||||
|
desc = ''
|
||||||
|
while True:
|
||||||
|
self.line = self.reader.readline()
|
||||||
|
if self.line == ' *\n':
|
||||||
|
desc += '\n'
|
||||||
|
else:
|
||||||
|
p = re.compile('^ \* \t\t(.*)')
|
||||||
|
capture = p.match(self.line)
|
||||||
|
if capture:
|
||||||
|
desc += capture.group(1) + '\n'
|
||||||
|
else:
|
||||||
|
break
|
||||||
|
return desc
|
||||||
|
|
||||||
|
def parse_ret(self):
|
||||||
|
p = re.compile('^ \* \tReturn$')
|
||||||
|
capture = p.match(self.line)
|
||||||
|
if not capture:
|
||||||
|
# Helper can have empty retval and we might be parsing another
|
||||||
|
# attribute: return but do not consume.
|
||||||
|
return ''
|
||||||
|
# Return value description can be several lines, some of them possibly
|
||||||
|
# empty, and it stops when another subsection title is met.
|
||||||
|
ret = ''
|
||||||
|
while True:
|
||||||
|
self.line = self.reader.readline()
|
||||||
|
if self.line == ' *\n':
|
||||||
|
ret += '\n'
|
||||||
|
else:
|
||||||
|
p = re.compile('^ \* \t\t(.*)')
|
||||||
|
capture = p.match(self.line)
|
||||||
|
if capture:
|
||||||
|
ret += capture.group(1) + '\n'
|
||||||
|
else:
|
||||||
|
break
|
||||||
|
return ret
|
||||||
|
|
||||||
|
def run(self):
|
||||||
|
# Advance to start of helper function descriptions.
|
||||||
|
offset = self.reader.read().find('* Start of BPF helper function descriptions:')
|
||||||
|
if offset == -1:
|
||||||
|
raise Exception('Could not find start of eBPF helper descriptions list')
|
||||||
|
self.reader.seek(offset)
|
||||||
|
self.reader.readline()
|
||||||
|
self.reader.readline()
|
||||||
|
self.line = self.reader.readline()
|
||||||
|
|
||||||
|
while True:
|
||||||
|
try:
|
||||||
|
helper = self.parse_helper()
|
||||||
|
self.helpers.append(helper)
|
||||||
|
except NoHelperFound:
|
||||||
|
break
|
||||||
|
|
||||||
|
self.reader.close()
|
||||||
|
print('Parsed description of %d helper function(s)' % len(self.helpers),
|
||||||
|
file=sys.stderr)
|
||||||
|
|
||||||
|
###############################################################################
|
||||||
|
|
||||||
|
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
|
||||||
|
"""
|
||||||
|
def __init__(self, helpers):
|
||||||
|
self.helpers = helpers
|
||||||
|
|
||||||
|
def print_header(self):
|
||||||
|
pass
|
||||||
|
|
||||||
|
def print_footer(self):
|
||||||
|
pass
|
||||||
|
|
||||||
|
def print_one(self, helper):
|
||||||
|
pass
|
||||||
|
|
||||||
|
def print_all(self):
|
||||||
|
self.print_header()
|
||||||
|
for helper in self.helpers:
|
||||||
|
self.print_one(helper)
|
||||||
|
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
|
||||||
|
"""
|
||||||
|
def print_header(self):
|
||||||
|
header = '''\
|
||||||
|
.. Copyright (C) All BPF authors and contributors from 2014 to present.
|
||||||
|
.. See git log include/uapi/linux/bpf.h in kernel tree for details.
|
||||||
|
..
|
||||||
|
.. %%%LICENSE_START(VERBATIM)
|
||||||
|
.. Permission is granted to make and distribute verbatim copies of this
|
||||||
|
.. manual provided the copyright notice and this permission notice are
|
||||||
|
.. preserved on all copies.
|
||||||
|
..
|
||||||
|
.. Permission is granted to copy and distribute modified versions of this
|
||||||
|
.. manual under the conditions for verbatim copying, provided that the
|
||||||
|
.. entire resulting derived work is distributed under the terms of a
|
||||||
|
.. permission notice identical to this one.
|
||||||
|
..
|
||||||
|
.. Since the Linux kernel and libraries are constantly changing, this
|
||||||
|
.. manual page may be incorrect or out-of-date. The author(s) assume no
|
||||||
|
.. responsibility for errors or omissions, or for damages resulting from
|
||||||
|
.. the use of the information contained herein. The author(s) may not
|
||||||
|
.. have taken the same level of care in the production of this manual,
|
||||||
|
.. which is licensed free of charge, as they might when working
|
||||||
|
.. professionally.
|
||||||
|
..
|
||||||
|
.. Formatted or processed versions of this manual, if unaccompanied by
|
||||||
|
.. the source, must acknowledge the copyright and authors of this work.
|
||||||
|
.. %%%LICENSE_END
|
||||||
|
..
|
||||||
|
.. 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
|
||||||
|
.. repository (header and footer).
|
||||||
|
|
||||||
|
===========
|
||||||
|
BPF-HELPERS
|
||||||
|
===========
|
||||||
|
-------------------------------------------------------------------------------
|
||||||
|
list of eBPF helper functions
|
||||||
|
-------------------------------------------------------------------------------
|
||||||
|
|
||||||
|
:Manual section: 7
|
||||||
|
|
||||||
|
DESCRIPTION
|
||||||
|
===========
|
||||||
|
|
||||||
|
The extended Berkeley Packet Filter (eBPF) subsystem consists in programs
|
||||||
|
written in a pseudo-assembly language, then attached to one of the several
|
||||||
|
kernel hooks and run in reaction of specific events. This framework differs
|
||||||
|
from the older, "classic" BPF (or "cBPF") in several aspects, one of them being
|
||||||
|
the ability to call special functions (or "helpers") from within a program.
|
||||||
|
These functions are restricted to a white-list of helpers defined in the
|
||||||
|
kernel.
|
||||||
|
|
||||||
|
These helpers are used by eBPF programs to interact with the system, or with
|
||||||
|
the context in which they work. For instance, they can be used to print
|
||||||
|
debugging messages, to get the time since the system was booted, to interact
|
||||||
|
with eBPF maps, or to manipulate network packets. Since there are several eBPF
|
||||||
|
program types, and that they do not run in the same context, each program type
|
||||||
|
can only call a subset of those helpers.
|
||||||
|
|
||||||
|
Due to eBPF conventions, a helper can not have more than five arguments.
|
||||||
|
|
||||||
|
Internally, eBPF programs call directly into the compiled helper functions
|
||||||
|
without requiring any foreign-function interface. As a result, calling helpers
|
||||||
|
introduces no overhead, thus offering excellent performance.
|
||||||
|
|
||||||
|
This document is an attempt to list and document the helpers available to eBPF
|
||||||
|
developers. They are sorted by chronological order (the oldest helpers in the
|
||||||
|
kernel at the top).
|
||||||
|
|
||||||
|
HELPERS
|
||||||
|
=======
|
||||||
|
'''
|
||||||
|
print(header)
|
||||||
|
|
||||||
|
def print_footer(self):
|
||||||
|
footer = '''
|
||||||
|
EXAMPLES
|
||||||
|
========
|
||||||
|
|
||||||
|
Example usage for most of the eBPF helpers listed in this manual page are
|
||||||
|
available within the Linux kernel sources, at the following locations:
|
||||||
|
|
||||||
|
* *samples/bpf/*
|
||||||
|
* *tools/testing/selftests/bpf/*
|
||||||
|
|
||||||
|
LICENSE
|
||||||
|
=======
|
||||||
|
|
||||||
|
eBPF programs can have an associated license, passed along with the bytecode
|
||||||
|
instructions to the kernel when the programs are loaded. The format for that
|
||||||
|
string is identical to the one in use for kernel modules (Dual licenses, such
|
||||||
|
as "Dual BSD/GPL", may be used). Some helper functions are only accessible to
|
||||||
|
programs that are compatible with the GNU Privacy License (GPL).
|
||||||
|
|
||||||
|
In order to use such helpers, the eBPF program must be loaded with the correct
|
||||||
|
license string passed (via **attr**) to the **bpf**\ () system call, and this
|
||||||
|
generally translates into the C source code of the program containing a line
|
||||||
|
similar to the following:
|
||||||
|
|
||||||
|
::
|
||||||
|
|
||||||
|
char ____license[] __attribute__((section("license"), used)) = "GPL";
|
||||||
|
|
||||||
|
IMPLEMENTATION
|
||||||
|
==============
|
||||||
|
|
||||||
|
This manual page is an effort to document the existing eBPF helper functions.
|
||||||
|
But as of this writing, the BPF sub-system is under heavy development. New eBPF
|
||||||
|
program or map types are added, along with new helper functions. Some helpers
|
||||||
|
are occasionally made available for additional program types. So in spite of
|
||||||
|
the efforts of the community, this page might not be up-to-date. If you want to
|
||||||
|
check by yourself what helper functions exist in your kernel, or what types of
|
||||||
|
programs they can support, here are some files among the kernel tree that you
|
||||||
|
may be interested in:
|
||||||
|
|
||||||
|
* *include/uapi/linux/bpf.h* is the main BPF header. It contains the full list
|
||||||
|
of all helper functions, as well as many other BPF definitions including most
|
||||||
|
of the flags, structs or constants used by the helpers.
|
||||||
|
* *net/core/filter.c* contains the definition of most network-related helper
|
||||||
|
functions, and the list of program types from which they can be used.
|
||||||
|
* *kernel/trace/bpf_trace.c* is the equivalent for most tracing program-related
|
||||||
|
helpers.
|
||||||
|
* *kernel/bpf/verifier.c* contains the functions used to check that valid types
|
||||||
|
of eBPF maps are used with a given helper function.
|
||||||
|
* *kernel/bpf/* directory contains other files in which additional helpers are
|
||||||
|
defined (for cgroups, sockmaps, etc.).
|
||||||
|
|
||||||
|
Compatibility between helper functions and program types can generally be found
|
||||||
|
in the files where helper functions are defined. Look for the **struct
|
||||||
|
bpf_func_proto** objects and for functions returning them: these functions
|
||||||
|
contain a list of helpers that a given program type can call. Note that the
|
||||||
|
**default:** label of the **switch ... case** used to filter helpers can call
|
||||||
|
other functions, themselves allowing access to additional helpers. The
|
||||||
|
requirement for GPL license is also in those **struct bpf_func_proto**.
|
||||||
|
|
||||||
|
Compatibility between helper functions and map types can be found in the
|
||||||
|
**check_map_func_compatibility**\ () function in file *kernel/bpf/verifier.c*.
|
||||||
|
|
||||||
|
Helper functions that invalidate the checks on **data** and **data_end**
|
||||||
|
pointers for network processing are listed in function
|
||||||
|
**bpf_helper_changes_pkt_data**\ () in file *net/core/filter.c*.
|
||||||
|
|
||||||
|
SEE ALSO
|
||||||
|
========
|
||||||
|
|
||||||
|
**bpf**\ (2),
|
||||||
|
**cgroups**\ (7),
|
||||||
|
**ip**\ (8),
|
||||||
|
**perf_event_open**\ (2),
|
||||||
|
**sendmsg**\ (2),
|
||||||
|
**socket**\ (7),
|
||||||
|
**tc-bpf**\ (8)'''
|
||||||
|
print(footer)
|
||||||
|
|
||||||
|
def print_proto(self, helper):
|
||||||
|
"""
|
||||||
|
Format function protocol with bold and italics markers. This makes RST
|
||||||
|
file less readable, but gives nice results in the manual page.
|
||||||
|
"""
|
||||||
|
proto = helper.proto_break_down()
|
||||||
|
|
||||||
|
print('**%s %s%s(' % (proto['ret_type'],
|
||||||
|
proto['ret_star'].replace('*', '\\*'),
|
||||||
|
proto['name']),
|
||||||
|
end='')
|
||||||
|
|
||||||
|
comma = ''
|
||||||
|
for a in proto['args']:
|
||||||
|
one_arg = '{}{}'.format(comma, a['type'])
|
||||||
|
if a['name']:
|
||||||
|
if a['star']:
|
||||||
|
one_arg += ' {}**\ '.format(a['star'].replace('*', '\\*'))
|
||||||
|
else:
|
||||||
|
one_arg += '** '
|
||||||
|
one_arg += '*{}*\\ **'.format(a['name'])
|
||||||
|
comma = ', '
|
||||||
|
print(one_arg, end='')
|
||||||
|
|
||||||
|
print(')**')
|
||||||
|
|
||||||
|
def print_one(self, helper):
|
||||||
|
self.print_proto(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))
|
||||||
|
|
||||||
|
print('')
|
||||||
|
|
||||||
|
###############################################################################
|
||||||
|
|
||||||
|
# If script is launched from scripts/ from kernel tree and can access
|
||||||
|
# ../include/uapi/linux/bpf.h, use it as a default name for the file to parse,
|
||||||
|
# otherwise the --filename argument will be required from the command line.
|
||||||
|
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')
|
||||||
|
|
||||||
|
argParser = argparse.ArgumentParser(description="""
|
||||||
|
Parse eBPF header file and generate documentation for eBPF helper functions.
|
||||||
|
The RST-formatted output produced can be turned into a manual page with the
|
||||||
|
rst2man utility.
|
||||||
|
""")
|
||||||
|
if (os.path.isfile(bpfh)):
|
||||||
|
argParser.add_argument('--filename', help='path to include/uapi/linux/bpf.h',
|
||||||
|
default=bpfh)
|
||||||
|
else:
|
||||||
|
argParser.add_argument('--filename', help='path to include/uapi/linux/bpf.h')
|
||||||
|
args = argParser.parse_args()
|
||||||
|
|
||||||
|
# Parse file.
|
||||||
|
headerParser = HeaderParser(args.filename)
|
||||||
|
headerParser.run()
|
||||||
|
|
||||||
|
# Print formatted output to standard output.
|
||||||
|
printer = PrinterRST(headerParser.helpers)
|
||||||
|
printer.print_all()
|
||||||
Loading…
Reference in New Issue