The program segfaulted if using the XSK_BTF_READ_INTO macro
with field as a C-string e.g. "rx_ktime".
Add comments to highlight this happens.
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Based on:
Subj: libbpf: Helpers to access XDP hints based on BTF definitions
https://lore.kernel.org/all/20210803010331.39453-15-ederson.desouza@intel.com/
From: Ederson de Souza <ederson.desouza@intel.com>
Ederson says:
A new set of functions to help get the BTF definition of XDP hints
structure and get the information based on it.
`xsk_umem__btf_id` helps retrieve the BTF id of XDP metadata.
`xsk_btf__init` sets up a context based on the BTF, including a hashmap,
so that subsequent queries are faster.
`xsk_btf__read` returns a pointer to the position in the XDP metadata
containing a given field.
`xsk_btf__has_field` checks the presence of a field in the BTF.
`xsk_btf__free` frees up the context.
Besides those, a macro `XSK_BTF_READ_INTO` acts as a convenient helper
to read the field contents into a given variable.
Note that currently, the hashmap used to speed-up offset location into
the BTF doesn't use the field name as a string as key to the hashmap. It
directly uses the pointer value instead, as it is expected that most of
time, field names will be addressed by a shared constant string residing
on read-only memory, thus saving some time. If this assumption is not
entirely true, this optimisation needs to be rethought (or discarded
altogether).
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
This is a copy of the kernels/libbpf hashmap
tools/lib/bpf/hashmap.{h,c}
The plan is to prototype an AF_XDP/xsk userspace API for accessing
BTF information, that should be moved to libbpf (or libxdp). Thus,
this hashmap code will become avail if successful.
Original kernel commit 553db8ba73df ("libbpf: add resizable non-thread
safe internal hashmap") (Author: Andrii Nakryiko). Thus, giving Andrii
author credit in this git commit.
Andrii Nakryiko said:
libbpf: add resizable non-thread safe internal hashmap
There is a need for fast point lookups inside libbpf for multiple use
cases (e.g., name resolution for BTF-to-C conversion, by-name lookups in
BTF for upcoming BPF CO-RE relocation support, etc). This patch
implements simple resizable non-thread safe hashmap using single linked
list chains.
Four different insert strategies are supported:
- HASHMAP_ADD - only add key/value if key doesn't exist yet;
- HASHMAP_SET - add key/value pair if key doesn't exist yet; otherwise,
update value;
- HASHMAP_UPDATE - update value, if key already exists; otherwise, do
nothing and return -ENOENT;
- HASHMAP_APPEND - always add key/value pair, even if key already exists.
This turns hashmap into a multimap by allowing multiple values to be
associated with the same key. Most useful read API for such hashmap is
hashmap__for_each_key_entry() iteration. If hashmap__find() is still
used, it will return last inserted key/value entry (first in a bucket
chain).
For HASHMAP_SET and HASHMAP_UPDATE, old key/value pair is returned, so
that calling code can handle proper memory management, if necessary.
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Don't allow loading the default xsk BPF-prog if not specifying
any BPF-prog. We have a need for our own BPf-prog.
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
To verify the contents of the incomming packets add a
function print_pkt_info() that decode part of the packet
headers and print IP-header src+dst (both IPv4 and IPv6).
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
The default frame_headroom seems to be zero as
define XSK_UMEM__DEFAULT_FRAME_HEADROOM is zero.
This patch does explicit xsk_umem_config setup.
Comment taken from kernel/samples/bpf/xdpsock_user.c.
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
This only works in skb-mode, other modes fail the bpf_xdp_adjust_meta
call and result in XDP_ABORTED. This only occurred on mlx5.
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
BPF program title (bpf_program__title) is getting deprecated
in libbpf use bpf_program__section_name() instead.
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
In-practice only 'xdp_stats_map' definition gets associated BTF,
as it uses the proper '__type' construct.
The AF_XDP map BPF_MAP_TYPE_XSKMAP doesn't know about BTF yet.
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
When not loading an XDP-prog the XSK library bits will load a
default XDP-prog.
In our use-case we always want to load our XDP-prog, which is
stored in af_xdp_kern.o.
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Something in fishy as it seems this BPF-object is not getting used.
Use old maps SEC defines until figuring out what is wrong,
but keep new dot-maps defines.
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
This USER_TARGETS_OBJS_DEPS allows makefiles to define
dependencies for USER_TARGETS_OBJS targets.
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
