linux.git/tools/lib/bpf/libbpf_internal.h, branch for-next

libbpf: Support opening bpf objects of either endianness

2024-10-04T00:47:36+00:00

Allow bpf_object__open() to access files of either endianness, and convert
included BPF programs to native byte-order in-memory for introspection.
Loading BPF objects of non-native byte-order is still disallowed however.

Signed-off-by: Tony Ambardar 
Signed-off-by: Andrii Nakryiko 
Link: https://lore.kernel.org/bpf/26353c1a1887a54400e1acd6c138fa90c99cdd40.1726475448.git.tony.ambardar@gmail.com
Signed-off-by: Alexei Starovoitov

libbpf: Support BTF.ext loading and output in either endianness

2024-10-04T00:47:36+00:00

Support for handling BTF data of either endianness was added in [1], but
did not include BTF.ext data for lack of use cases. Later, support for
static linking [2] provided a use case, but this feature and later ones
were restricted to native-endian usage.

Add support for BTF.ext handling in either endianness. Convert BTF.ext data
to native endianness when read into memory for further processing, and
support raw data access that restores the original byte-order for output.
Add internal header functions for byte-swapping func, line, and core info
records.

Add new API functions btf_ext__endianness() and btf_ext__set_endianness()
for query and setting byte-order, as already exist for BTF data.

[1] 3289959b97ca ("libbpf: Support BTF loading and raw data output in both endianness")
[2] 8fd27bf69b86 ("libbpf: Add BPF static linker BTF and BTF.ext support")

Signed-off-by: Tony Ambardar 
Signed-off-by: Andrii Nakryiko 
Link: https://lore.kernel.org/bpf/133407ab20e0dd5c07cab2a6fa7879dee1ffa4bc.1726475448.git.tony.ambardar@gmail.com
Signed-off-by: Alexei Starovoitov

libbpf: Fix header comment typos for BTF.ext

2024-10-04T00:47:36+00:00

Mention struct btf_ext_info_sec rather than non-existent btf_sec_func_info
in BTF.ext struct documentation.

Signed-off-by: Tony Ambardar 
Signed-off-by: Andrii Nakryiko 
Link: https://lore.kernel.org/bpf/cde65e01a5f2945c578485fab265ef711e2daeb6.1726475448.git.tony.ambardar@gmail.com
Signed-off-by: Alexei Starovoitov

libbpf: Split BTF relocation

2024-06-17T21:38:31+00:00

Map distilled base BTF type ids referenced in split BTF and their
references to the base BTF passed in, and if the mapping succeeds,
reparent the split BTF to the base BTF.

Relocation is done by first verifying that distilled base BTF
only consists of named INT, FLOAT, ENUM, FWD, STRUCT and
UNION kinds; then we sort these to speed lookups.  Once sorted,
the base BTF is iterated, and for each relevant kind we check
for an equivalent in distilled base BTF.  When found, the
mapping from distilled -> base BTF id and string offset is recorded.
In establishing mappings, we need to ensure we check STRUCT/UNION
size when the STRUCT/UNION is embedded in a split BTF STRUCT/UNION,
and when duplicate names exist for the same STRUCT/UNION.  Otherwise
size is ignored in matching STRUCT/UNIONs.

Once all mappings are established, we can update type ids
and string offsets in split BTF and reparent it to the new base.

Signed-off-by: Alan Maguire 
Signed-off-by: Andrii Nakryiko 
Acked-by: Eduard Zingerman 
Link: https://lore.kernel.org/bpf/20240613095014.357981-4-alan.maguire@oracle.com

libbpf: Remove callback-based type/string BTF field visitor helpers

2024-06-05T14:54:45+00:00

Now that all libbpf/bpftool code switched to btf_field_iter, remove
btf_type_visit_type_ids() and btf_type_visit_str_offs() callback-based
helpers as not needed anymore.

Signed-off-by: Andrii Nakryiko 
Signed-off-by: Daniel Borkmann 
Tested-by: Alan Maguire 
Acked-by: Eduard Zingerman 
Acked-by: Jiri Olsa 
Link: https://lore.kernel.org/bpf/20240605001629.4061937-6-andrii@kernel.org

libbpf: Make use of BTF field iterator in BPF linker code

2024-06-05T14:54:32+00:00

Switch all BPF linker code dealing with iterating BTF type ID and string
offset fields to new btf_field_iter facilities.

Signed-off-by: Andrii Nakryiko 
Signed-off-by: Daniel Borkmann 
Tested-by: Alan Maguire 
Acked-by: Eduard Zingerman 
Acked-by: Jiri Olsa 
Link: https://lore.kernel.org/bpf/20240605001629.4061937-3-andrii@kernel.org

libbpf: Add BTF field iterator

2024-06-05T14:54:26+00:00

Implement iterator-based type ID and string offset BTF field iterator.
This is used extensively in BTF-handling code and BPF linker code for
various sanity checks, rewriting IDs/offsets, etc. Currently this is
implemented as visitor pattern calling custom callbacks, which makes the
logic (especially in simple cases) unnecessarily obscure and harder to
follow.

Having equivalent functionality using iterator pattern makes for simpler
to understand and maintain code. As we add more code for BTF processing
logic in libbpf, it's best to switch to iterator pattern before adding
more callback-based code.

The idea for iterator-based implementation is to record offsets of
necessary fields within fixed btf_type parts (which should be iterated
just once), and, for kinds that have multiple members (based on vlen
field), record where in each member necessary fields are located.

Generic iteration code then just keeps track of last offset that was
returned and handles N members correctly. Return type is just u32
pointer, where NULL is returned when all relevant fields were already
iterated.

Signed-off-by: Andrii Nakryiko 
Signed-off-by: Daniel Borkmann 
Tested-by: Alan Maguire 
Acked-by: Eduard Zingerman 
Acked-by: Jiri Olsa 
Link: https://lore.kernel.org/bpf/20240605001629.4061937-2-andrii@kernel.org

libbpf: keep FD_CLOEXEC flag when dup()'ing FD

2024-06-01T03:35:55+00:00

Make sure to preserve and/or enforce FD_CLOEXEC flag on duped FDs.
Use dup3() with O_CLOEXEC flag for that.

Without this fix libbpf effectively clears FD_CLOEXEC flag on each of BPF
map/prog FD, which is definitely not the right or expected behavior.

Reported-by: Lennart Poettering 
Fixes: bc308d011ab8 ("libbpf: call dup2() syscall directly")
Signed-off-by: Andrii Nakryiko 
Acked-by: Jiri Olsa 
Link: https://lore.kernel.org/r/20240529223239.504241-1-andrii@kernel.org
Signed-off-by: Alexei Starovoitov

libbpf: Mark libbpf_kallsyms_parse static function

2024-03-29T01:31:41+00:00

Currently libbpf_kallsyms_parse() function is declared as a global
function but actually it is not a API and there is no external
users in bpftool/bpf-selftests. So let us mark the function as
static.

Signed-off-by: Yonghong Song 
Link: https://lore.kernel.org/r/20240326041453.1197949-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov

libbpf: Rewrite btf datasec names starting from '?'

2024-03-06T23:18:16+00:00

Optional struct_ops maps are defined using question mark at the start
of the section name, e.g.:

    SEC("?.struct_ops")
    struct test_ops optional_map = { ... };

This commit teaches libbpf to detect if kernel allows '?' prefix
in datasec names, and if it doesn't then to rewrite such names
by replacing '?' with '_', e.g.:

    DATASEC ?.struct_ops -> DATASEC _.struct_ops

Signed-off-by: Eduard Zingerman 
Signed-off-by: Andrii Nakryiko 
Link: https://lore.kernel.org/bpf/20240306104529.6453-13-eddyz87@gmail.com