linux.git/tools/lib/bpf/libbpf.c, branch v5.19

libbpf: Fix typo in comment

2022-05-23T18:24:50+00:00

Spelling mistake (triple letters) in comment.
Detected with the help of Coccinelle.

Signed-off-by: Julia Lawall 
Signed-off-by: Andrii Nakryiko 
Acked-by: Daniel Müller 
Link: https://lore.kernel.org/bpf/20220521111145.81697-71-Julia.Lawall@inria.fr

libbpf: fix memory leak in attach_tp for target-less tracepoint program

2022-05-16T20:42:44+00:00

Fix sec_name memory leak if user defines target-less SEC("tp").

Fixes: 9af8efc45eb1 ("libbpf: Allow "incomplete" basic tracing SEC() definitions")
Signed-off-by: Andrii Nakryiko 
Acked-by: David Vernet 
Link: https://lore.kernel.org/r/20220516184547.3204674-1-andrii@kernel.org
Signed-off-by: Alexei Starovoitov

libbpf: Add safer high-level wrappers for map operations

2022-05-13T13:15:02+00:00

Add high-level API wrappers for most common and typical BPF map
operations that works directly on instances of struct bpf_map * (so
you don't have to call bpf_map__fd()) and validate key/value size
expectations.

These helpers require users to specify key (and value, where
appropriate) sizes when performing lookup/update/delete/etc. This forces
user to actually think and validate (for themselves) those. This is
a good thing as user is expected by kernel to implicitly provide correct
key/value buffer sizes and kernel will just read/write necessary amount
of data. If it so happens that user doesn't set up buffers correctly
(which bit people for per-CPU maps especially) kernel either randomly
overwrites stack data or return -EFAULT, depending on user's luck and
circumstances. These high-level APIs are meant to prevent such
unpleasant and hard to debug bugs.

This patch also adds bpf_map_delete_elem_flags() low-level API and
requires passing flags to bpf_map__delete_elem() API for consistency
across all similar APIs, even though currently kernel doesn't expect
any extra flags for BPF_MAP_DELETE_ELEM operation.

List of map operations that get these high-level APIs:

  - bpf_map_lookup_elem;
  - bpf_map_update_elem;
  - bpf_map_delete_elem;
  - bpf_map_lookup_and_delete_elem;
  - bpf_map_get_next_key.

Signed-off-by: Andrii Nakryiko 
Signed-off-by: Daniel Borkmann 
Link: https://lore.kernel.org/bpf/20220512220713.2617964-1-andrii@kernel.org

libbpf: Add bpf_program__set_insns function

2022-05-11T12:15:17+00:00

Adding bpf_program__set_insns that allows to set new instructions
for a BPF program.

This is a very advanced libbpf API and users need to know what
they are doing. This should be used from prog_prepare_load_fn
callback only.

We can have changed instructions after calling prog_prepare_load_fn
callback, reloading them.

One of the users of this new API will be perf's internal BPF prologue
generation.

Signed-off-by: Jiri Olsa 
Signed-off-by: Daniel Borkmann 
Acked-by: Andrii Nakryiko 
Link: https://lore.kernel.org/bpf/20220510074659.2557731-2-jolsa@kernel.org

libbpf: Clean up ringbuf size adjustment implementation

2022-05-11T12:06:29+00:00

Drop unused iteration variable, move overflow prevention check into the
for loop.

Fixes: 0087a681fa8c ("libbpf: Automatically fix up BPF_MAP_TYPE_RINGBUF size, if necessary")
Reported-by: Nathan Chancellor 
Signed-off-by: Andrii Nakryiko 
Signed-off-by: Daniel Borkmann 
Link: https://lore.kernel.org/bpf/20220510185159.754299-1-andrii@kernel.org

libbpf: Assign cookies to links in libbpf.

2022-05-11T04:58:40+00:00

Add a cookie field to the attributes of bpf_link_create().
Add bpf_program__attach_trace_opts() to attach a cookie to a link.

Signed-off-by: Kui-Feng Lee 
Signed-off-by: Alexei Starovoitov 
Signed-off-by: Andrii Nakryiko 
Acked-by: Andrii Nakryiko 
Link: https://lore.kernel.org/bpf/20220510205923.3206889-5-kuifeng@fb.com

libbpf: Automatically fix up BPF_MAP_TYPE_RINGBUF size, if necessary

2022-05-09T15:15:32+00:00

Kernel imposes a pretty particular restriction on ringbuf map size. It
has to be a power-of-2 multiple of page size. While generally this isn't
hard for user to satisfy, sometimes it's impossible to do this
declaratively in BPF source code or just plain inconvenient to do at
runtime.

One such example might be BPF libraries that are supposed to work on
different architectures, which might not agree on what the common page
size is.

Let libbpf find the right size for user instead, if it turns out to not
satisfy kernel requirements. If user didn't set size at all, that's most
probably a mistake so don't upsize such zero size to one full page,
though. Also we need to be careful about not overflowing __u32
max_entries.

Signed-off-by: Andrii Nakryiko 
Signed-off-by: Daniel Borkmann 
Link: https://lore.kernel.org/bpf/20220509004148.1801791-9-andrii@kernel.org

libbpf: Allow to opt-out from creating BPF maps

2022-04-29T03:03:29+00:00

Add bpf_map__set_autocreate() API that allows user to opt-out from
libbpf automatically creating BPF map during BPF object load.

This is a useful feature when building CO-RE-enabled BPF application
that takes advantage of some new-ish BPF map type (e.g., socket-local
storage) if kernel supports it, but otherwise uses some alternative way
(e.g., extra HASH map). In such case, being able to disable the creation
of a map that kernel doesn't support allows to successfully create and
load BPF object file with all its other maps and programs.

It's still up to user to make sure that no "live" code in any of their BPF
programs are referencing such map instance, which can be achieved by
guarding such code with CO-RE relocation check or by using .rodata
global variables.

If user fails to properly guard such code to turn it into "dead code",
libbpf will helpfully post-process BPF verifier log and will provide
more meaningful error and map name that needs to be guarded properly. As
such, instead of:

  ; value = bpf_map_lookup_elem(&missing_map, &zero);
  4: (85) call unknown#2001000000
  invalid func unknown#2001000000

... user will see:

  ; value = bpf_map_lookup_elem(&missing_map, &zero);
  4: 
  BPF map 'missing_map' is referenced but wasn't created

Signed-off-by: Andrii Nakryiko 
Signed-off-by: Alexei Starovoitov 
Link: https://lore.kernel.org/bpf/20220428041523.4089853-4-andrii@kernel.org

libbpf: Use libbpf_mem_ensure() when allocating new map

2022-04-29T03:03:29+00:00

Reuse libbpf_mem_ensure() when adding a new map to the list of maps
inside bpf_object. It takes care of proper resizing and reallocating of
map array and zeroing out newly allocated memory.

Signed-off-by: Andrii Nakryiko 
Signed-off-by: Alexei Starovoitov 
Link: https://lore.kernel.org/bpf/20220428041523.4089853-3-andrii@kernel.org

libbpf: Append "..." in fixed up log if CO-RE spec is truncated

2022-04-29T03:03:29+00:00

Detect CO-RE spec truncation and append "..." to make user aware that
there was supposed to be more of the spec there.

Signed-off-by: Andrii Nakryiko 
Signed-off-by: Alexei Starovoitov 
Link: https://lore.kernel.org/bpf/20220428041523.4089853-2-andrii@kernel.org