linux-toradex.git/tools/lib/bpf/libbpf.h, branch v6.15-rc1

libbpf: Split bpf object load into prepare/load

2025-03-15T18:48:28+00:00

Introduce bpf_object__prepare API: additional intermediate preparation
step that performs ELF processing, relocations, prepares final state of
BPF program instructions (accessible with bpf_program__insns()), creates
and (potentially) pins maps, and stops short of loading BPF programs.

We anticipate few use cases for this API, such as:
* Use prepare to initialize bpf_token, without loading freplace
programs, unlocking possibility to lookup BTF of other programs.
* Execute prepare to obtain finalized BPF program instructions without
loading programs, enabling tools like veristat to process one program at
a time, without incurring cost of ELF parsing and processing.

Signed-off-by: Mykyta Yatsenko 
Signed-off-by: Andrii Nakryiko 
Link: https://lore.kernel.org/bpf/20250303135752.158343-4-mykyta.yatsenko5@gmail.com
Signed-off-by: Alexei Starovoitov

libbpf: Add unique_match option for multi kprobe

2025-01-10T21:11:42+00:00

Jordan reported an issue in Meta production environment where func
try_to_wake_up() is renamed to try_to_wake_up.llvm.() by clang
compiler at lto mode. The original 'kprobe/try_to_wake_up' does not
work any more since try_to_wake_up() does not match the actual func
name in /proc/kallsyms.

There are a couple of ways to resolve this issue. For example, in
attach_kprobe(), we could do lookup in /proc/kallsyms so try_to_wake_up()
can be replaced by try_to_wake_up.llvm.(). Or we can force users
to use bpf_program__attach_kprobe() where they need to lookup
/proc/kallsyms to find out try_to_wake_up.llvm.(). But these two
approaches requires extra work by either libbpf or user.

Luckily, suggested by Andrii, multi kprobe already supports wildcard ('*')
for symbol matching. In the above example, 'try_to_wake_up*' can match
to try_to_wake_up() or try_to_wake_up.llvm.() and this allows
bpf prog works for different kernels as some kernels may have
try_to_wake_up() and some others may have try_to_wake_up.llvm.().

The original intention is to kprobe try_to_wake_up() only, so an optional
field unique_match is added to struct bpf_kprobe_multi_opts. If the
field is set to true, the number of matched functions must be one.
Otherwise, the attachment will fail. In the above case, multi kprobe
with 'try_to_wake_up*' and unique_match preserves user functionality.

Reported-by: Jordan Rome 
Suggested-by: Andrii Nakryiko 
Signed-off-by: Yonghong Song 
Signed-off-by: Andrii Nakryiko 
Link: https://lore.kernel.org/bpf/20250109174023.3368432-1-yonghong.song@linux.dev

libbpf: Extend linker API to support in-memory ELF files

2024-12-12T23:16:53+00:00

The new_fd and add_fd functions correspond to the original new and
add_file functions, but accept an FD instead of a file name. This
gives API consumers the option of using anonymous files/memfds to
avoid writing ELFs to disk.

This new API will be useful for performing linking as part of
bpftrace's JIT compilation.

The add_buf function is a convenience wrapper that does the work of
creating a memfd for the caller.

Signed-off-by: Alastair Robertson 
Signed-off-by: Andrii Nakryiko 
Link: https://lore.kernel.org/bpf/20241211164030.573042-3-ajor@meta.com

libbpf: Add support for uprobe multi session attach

2024-11-11T16:18:06+00:00

Adding support to attach program in uprobe session mode
with bpf_program__attach_uprobe_multi function.

Adding session bool to bpf_uprobe_multi_opts struct that allows
to load and attach the bpf program via uprobe session.
the attachment to create uprobe multi session.

Also adding new program loader section that allows:
  SEC("uprobe.session/bpf_fentry_test*")

and loads/attaches uprobe program as uprobe session.

Adding sleepable hook (uprobe.session.s) as well.

Signed-off-by: Jiri Olsa 
Signed-off-by: Andrii Nakryiko 
Acked-by: Andrii Nakryiko 
Link: https://lore.kernel.org/bpf/20241108134544.480660-6-jolsa@kernel.org

libbpf: Add bpf_object__token_fd accessor

2024-09-13T02:07:13+00:00

Add a LIBBPF_API function to retrieve the token_fd from a bpf_object.

Without this accessor, if user needs a token FD they have to get it
manually via bpf_token_create, even though a token might have been
already created by bpf_object__load.

Suggested-by: Andrii Nakryiko 
Signed-off-by: Ihor Solodrai 
Signed-off-by: Andrii Nakryiko 
Link: https://lore.kernel.org/bpf/20240913001858.3345583-1-ihor.solodrai@pm.me

libbpf: Fix some typos in comments

2024-09-09T23:05:40+00:00

Fix some spelling errors in the code comments of libbpf:

betwen -> between
paremeters -> parameters
knowning -> knowing
definiton -> definition
compatiblity -> compatibility
overriden -> overridden
occured -> occurred
proccess -> process
managment -> management
nessary -> necessary

Signed-off-by: Yusheng Zheng 
Signed-off-by: Andrii Nakryiko 
Link: https://lore.kernel.org/bpf/20240909225952.30324-1-yunwei356@gmail.com

libbpf: Auto-attach struct_ops BPF maps in BPF skeleton

2024-06-06T17:06:05+00:00

Similarly to `bpf_program`, support `bpf_map` automatic attachment in
`bpf_object__attach_skeleton`. Currently only struct_ops maps could be
attached.

On bpftool side, code-generate links in skeleton struct for struct_ops maps.
Similarly to `bpf_program_skeleton`, set links in `bpf_map_skeleton`.

On libbpf side, extend `bpf_map` with new `autoattach` field to support
enabling or disabling autoattach functionality, introducing
getter/setter for this field.

`bpf_object__(attach|detach)_skeleton` is extended with
attaching/detaching struct_ops maps logic.

Signed-off-by: Mykyta Yatsenko 
Signed-off-by: Andrii Nakryiko 
Link: https://lore.kernel.org/bpf/20240605175135.117127-1-yatsenko@meta.com

libbpf: Configure log verbosity with env variable

2024-05-28T23:25:06+00:00

Configure logging verbosity by setting LIBBPF_LOG_LEVEL environment
variable, which is applied only to default logger. Once user set their
custom logging callback, it is up to them to handle filtering.

Signed-off-by: Mykyta Yatsenko 
Signed-off-by: Andrii Nakryiko 
Link: https://lore.kernel.org/bpf/20240524131840.114289-1-yatsenko@meta.com

libbpf: Add support for kprobe session attach

2024-04-30T16:45:53+00:00

Adding support to attach program in kprobe session mode
with bpf_program__attach_kprobe_multi_opts function.

Adding session bool to bpf_kprobe_multi_opts struct that allows
to load and attach the bpf program via kprobe session.
the attachment to create kprobe multi session.

Also adding new program loader section that allows:
 SEC("kprobe.session/bpf_fentry_test*")

and loads/attaches kprobe program as kprobe session.

Signed-off-by: Jiri Olsa 
Signed-off-by: Andrii Nakryiko 
Acked-by: Andrii Nakryiko 
Link: https://lore.kernel.org/bpf/20240430112830.1184228-5-jolsa@kernel.org

libbpf: Add bpf_link support for BPF_PROG_TYPE_SOCKMAP

2024-04-11T02:52:25+00:00

Introduce a libbpf API function bpf_program__attach_sockmap()
which allow user to get a bpf_link for their corresponding programs.

Acked-by: Andrii Nakryiko 
Acked-by: Eduard Zingerman 
Reviewed-by: John Fastabend 
Signed-off-by: Yonghong Song 
Link: https://lore.kernel.org/r/20240410043532.3737722-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov