Add new variants of perf_buffer__new() and perf_buffer__new_raw() that
use OPTS-based options for future extensibility ([0]). Given all the
currently used API names are best fits, re-use them and use
___libbpf_override() approach and symbol versioning to preserve ABI and
source code compatibility. struct perf_buffer_opts and struct
perf_buffer_raw_opts are kept as well, but they are restructured such
that they are OPTS-based when used with new APIs. For struct
perf_buffer_raw_opts we keep few fields intact, so we have to also
preserve the memory location of them both when used as OPTS and for
legacy API variants. This is achieved with anonymous padding for OPTS
"incarnation" of the struct. These pads can be eventually used for new
options.
[0] Closes: https://github.com/libbpf/libbpf/issues/311
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211111053624.190580-6-andrii@kernel.org
Change btf_dump__new() and corresponding struct btf_dump_ops structure
to be extensible by using OPTS "framework" ([0]). Given we don't change
the names, we use a similar approach as with bpf_prog_load(), but this
time we ended up with two APIs with the same name and same number of
arguments, so overloading based on number of arguments with
___libbpf_override() doesn't work.
Instead, use "overloading" based on types. In this particular case,
print callback has to be specified, so we detect which argument is
a callback. If it's 4th (last) argument, old implementation of API is
used by user code. If not, it must be 2nd, and thus new implementation
is selected. The rest is handled by the same symbol versioning approach.
btf_ext argument is dropped as it was never used and isn't necessary
either. If in the future we'll need btf_ext, that will be added into
OPTS-based struct btf_dump_opts.
struct btf_dump_opts is reused for both old API and new APIs. ctx field
is marked deprecated in v0.7+ and it's put at the same memory location
as OPTS's sz field. Any user of new-style btf_dump__new() will have to
set sz field and doesn't/shouldn't use ctx, as ctx is now passed along
the callback as mandatory input argument, following the other APIs in
libbpf that accept callbacks consistently.
Again, this is quite ugly in implementation, but is done in the name of
backwards compatibility and uniform and extensible future APIs (at the
same time, sigh). And it will be gone in libbpf 1.0.
[0] Closes: https://github.com/libbpf/libbpf/issues/283
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211111053624.190580-5-andrii@kernel.org
btf__dedup() and struct btf_dedup_opts were added before we figured out
OPTS mechanism. As such, btf_dedup_opts is non-extensible without
breaking an ABI and potentially crashing user application.
Unfortunately, btf__dedup() and btf_dedup_opts are short and succinct
names that would be great to preserve and use going forward. So we use
___libbpf_override() macro approach, used previously for bpf_prog_load()
API, to define a new btf__dedup() variant that accepts only struct btf *
and struct btf_dedup_opts * arguments, and rename the old btf__dedup()
implementation into btf__dedup_deprecated(). This keeps both source and
binary compatibility with old and new applications.
The biggest problem was struct btf_dedup_opts, which wasn't OPTS-based,
and as such doesn't have `size_t sz;` as a first field. But btf__dedup()
is a pretty rarely used API and I believe that the only currently known
users (besides selftests) are libbpf's own bpf_linker and pahole.
Neither use case actually uses options and just passes NULL. So instead
of doing extra hacks, just rewrite struct btf_dedup_opts into OPTS-based
one, move btf_ext argument into those opts (only bpf_linker needs to
dedup btf_ext, so it's not a typical thing to specify), and drop never
used `dont_resolve_fwds` option (it was never used anywhere, AFAIK, it
makes BTF dedup much less useful and efficient).
Just in case, for old implementation, btf__dedup_deprecated(), detect
non-NULL options and error out with helpful message, to help users
migrate, if there are any user playing with btf__dedup().
The last remaining piece is dedup_table_size, which is another
anachronism from very early days of BTF dedup. Since then it has been
reduced to the only valid value, 1, to request forced hash collisions.
This is only used during testing. So instead introduce a bool flag to
force collisions explicitly.
This patch also adapts selftests to new btf__dedup() and btf_dedup_opts
use to avoid selftests breakage.
[0] Closes: https://github.com/libbpf/libbpf/issues/281
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211111053624.190580-4-andrii@kernel.org
Add bpf_program__flags() API to retrieve prog_flags that will be (or
were) supplied to BPF_PROG_LOAD command.
Also add bpf_program__set_extra_flags() API to allow to set *extra*
flags, in addition to those determined by program's SEC() definition.
Such flags are logically OR'ed with libbpf-derived flags.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211111051758.92283-2-andrii@kernel.org
This deprecation annotation has no effect because for struct deprecation
attribute has to be declared after struct definition. But instead of
moving it to the end of struct definition, remove it. When deprecation
will go in effect at libbpf v0.7, this deprecation attribute will cause
libbpf's own source code compilation to trigger deprecation warnings,
which is unavoidable because libbpf still has to support that API.
So keep deprecation of APIs, but don't mark structs used in API as
deprecated.
Fixes: e21d585cb3db ("libbpf: Deprecate multi-instance bpf_program APIs")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Dave Marchevsky <davemarchevsky@fb.com>
Link: https://lore.kernel.org/bpf/20211103220845.2676888-8-andrii@kernel.org
Add a new unified OPTS-based low-level API for program loading,
bpf_prog_load() ([0]). bpf_prog_load() accepts few "mandatory"
parameters as input arguments (program type, name, license,
instructions) and all the other optional (as in not required to specify
for all types of BPF programs) fields into struct bpf_prog_load_opts.
This makes all the other non-extensible APIs variant for BPF_PROG_LOAD
obsolete and they are slated for deprecation in libbpf v0.7:
- bpf_load_program();
- bpf_load_program_xattr();
- bpf_verify_program().
Implementation-wise, internal helper libbpf__bpf_prog_load is refactored
to become a public bpf_prog_load() API. struct bpf_prog_load_params used
internally is replaced by public struct bpf_prog_load_opts.
Unfortunately, while conceptually all this is pretty straightforward,
the biggest complication comes from the already existing bpf_prog_load()
*high-level* API, which has nothing to do with BPF_PROG_LOAD command.
We try really hard to have a new API named bpf_prog_load(), though,
because it maps naturally to BPF_PROG_LOAD command.
For that, we rename old bpf_prog_load() into bpf_prog_load_deprecated()
and mark it as COMPAT_VERSION() for shared library users compiled
against old version of libbpf. Statically linked users and shared lib
users compiled against new version of libbpf headers will get "rerouted"
to bpf_prog_deprecated() through a macro helper that decides whether to
use new or old bpf_prog_load() based on number of input arguments (see
___libbpf_overload in libbpf_common.h).
To test that existing
bpf_prog_load()-using code compiles and works as expected, I've compiled
and ran selftests as is. I had to remove (locally) selftest/bpf/Makefile
-Dbpf_prog_load=bpf_prog_test_load hack because it was conflicting with
the macro-based overload approach. I don't expect anyone else to do
something like this in practice, though. This is testing-specific way to
replace bpf_prog_load() calls with special testing variant of it, which
adds extra prog_flags value. After testing I kept this selftests hack,
but ensured that we use a new bpf_prog_load_deprecated name for this.
This patch also marks bpf_prog_load() and bpf_prog_load_xattr() as deprecated.
bpf_object interface has to be used for working with struct bpf_program.
Libbpf doesn't support loading just a bpf_program.
The silver lining is that when we get to libbpf 1.0 all these
complication will be gone and we'll have one clean bpf_prog_load()
low-level API with no backwards compatibility hackery surrounding it.
[0] Closes: https://github.com/libbpf/libbpf/issues/284
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211103220845.2676888-4-andrii@kernel.org
It's confusing that libbpf-provided helper macro doesn't start with
LIBBPF. Also "declare" vs "define" is confusing terminology, I can never
remember and always have to look up previous examples.
Bypass both issues by renaming DECLARE_LIBBPF_OPTS into a short and
clean LIBBPF_OPTS. To avoid breaking existing code, provide:
#define DECLARE_LIBBPF_OPTS LIBBPF_OPTS
in libbpf_legacy.h. We can decide later if we ever want to remove it or
we'll keep it forever because it doesn't add any maintainability burden.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Dave Marchevsky <davemarchevsky@fb.com>
Link: https://lore.kernel.org/bpf/20211103220845.2676888-2-andrii@kernel.org
e_shnum does include section #0 and as such is exactly the number of ELF
sections that we need to allocate memory for to use section indices as
array indices. Fix the off-by-one error.
This is purely accounting fix, previously we were overallocating one
too many array items. But no correctness errors otherwise.
Fixes: 25bbbd7a444b ("libbpf: Remove assumptions about uniqueness of .rodata/.data/.bss maps")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20211103173213.1376990-5-andrii@kernel.org
.BTF and .BTF.ext ELF sections should have SHT_PROGBITS type and contain
data. If they are not, ELF is invalid or corrupted, so bail out.
Otherwise this can lead to data->d_buf being NULL and SIGSEGV later on.
Reported by oss-fuzz project.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20211103173213.1376990-4-andrii@kernel.org
The name of the API doesn't convey clearly that this size is in number
of bytes (there needed to be a separate comment to make this clear in
libbpf.h). Further, measuring the size of BPF program in bytes is not
exactly the best fit, because BPF programs always consist of 8-byte
instructions. As such, bpf_program__insn_cnt() is a better alternative
in pretty much any imaginable case.
So schedule bpf_program__size() deprecation starting from v0.7 and it
will be removed in libbpf 1.0.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211025224531.1088894-5-andrii@kernel.org
Schedule deprecation of a set of APIs that are related to multi-instance
bpf_programs:
- bpf_program__set_prep() ([0]);
- bpf_program__{set,unset}_instance() ([1]);
- bpf_program__nth_fd().
These APIs are obscure, very niche, and don't seem to be used much in
practice. bpf_program__set_prep() is pretty useless for anything but the
simplest BPF programs, as it doesn't allow to adjust BPF program load
attributes, among other things. In short, it already bitrotted and will
bitrot some more if not removed.
With bpf_program__insns() API, which gives access to post-processed BPF
program instructions of any given entry-point BPF program, it's now
possible to do whatever necessary adjustments were possible with
set_prep() API before, but also more. Given any such use case is
automatically an advanced use case, requiring users to stick to
low-level bpf_prog_load() APIs and managing their own prog FDs is
reasonable.
[0] Closes: https://github.com/libbpf/libbpf/issues/299
[1] Closes: https://github.com/libbpf/libbpf/issues/300
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211025224531.1088894-4-andrii@kernel.org
Add APIs providing read-only access to bpf_program BPF instructions ([0]).
This is useful for diagnostics purposes, but it also allows a cleaner
support for cloning BPF programs after libbpf did all the FD resolution
and CO-RE relocations, subprog instructions appending, etc. Currently,
cloning BPF program is possible only through hijacking a half-broken
bpf_program__set_prep() API, which doesn't really work well for anything
but most primitive programs. For instance, set_prep() API doesn't allow
adjusting BPF program load parameters which are necessary for loading
fentry/fexit BPF programs (the case where BPF program cloning is
a necessity if doing some sort of mass-attachment functionality).
Given bpf_program__set_prep() API is set to be deprecated, having
a cleaner alternative is a must. libbpf internally already keeps track
of linear array of struct bpf_insn, so it's not hard to expose it. The
only gotcha is that libbpf previously freed instructions array during
bpf_object load time, which would make this API much less useful overall,
because in between bpf_object__open() and bpf_object__load() a lot of
changes to instructions are done by libbpf.
So this patch makes libbpf hold onto prog->insns array even after BPF
program loading. I think this is a small price for added functionality
and improved introspection of BPF program code.
See retsnoop PR ([1]) for how it can be used in practice and code
savings compared to relying on bpf_program__set_prep().
[0] Closes: https://github.com/libbpf/libbpf/issues/298
[1] https://github.com/anakryiko/retsnoop/pull/1
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211025224531.1088894-3-andrii@kernel.org
Original code assumed fixed and correct BTF header length. That's not
always the case, though, so fix this bug with a proper additional check.
And use actual header length instead of sizeof(struct btf_header) in
sanity checks.
Fixes: 8a138aed4a80 ("bpf: btf: Add BTF support to libbpf")
Reported-by: Evgeny Vereshchagin <evvers@ya.ru>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211023003157.726961-2-andrii@kernel.org
btf_header's str_off+str_len or type_off+type_len can overflow as they
are u32s. This will lead to bypassing the sanity checks during BTF
parsing, resulting in crashes afterwards. Fix by using 64-bit signed
integers for comparison.
Fixes: d8123624506c ("libbpf: Fix BTF data layout checks and allow empty BTF")
Reported-by: Evgeny Vereshchagin <evvers@ya.ru>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211023003157.726961-1-andrii@kernel.org
Building libbpf sources out of kernel tree (in Github repo) we run into
compilation error due to unknown __aligned attribute. It must be coming
from some kernel header, which is not available to Github sources. Use
explicit __attribute__((aligned(16))) instead.
Fixes: 961632d54163 ("libbpf: Fix dumping non-aligned __int128")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211022192502.2975553-1-andrii@kernel.org
Map name that's assigned to internal maps (.rodata, .data, .bss, etc)
consist of a small prefix of bpf_object's name and ELF section name as
a suffix. This makes it hard for users to "guess" the name to use for
looking up by name with bpf_object__find_map_by_name() API.
One proposal was to drop object name prefix from the map name and just
use ".rodata", ".data", etc, names. One downside called out was that
when multiple BPF applications are active on the host, it will be hard
to distinguish between multiple instances of .rodata and know which BPF
object (app) they belong to. Having few first characters, while quite
limiting, still can give a bit of a clue, in general.
Note, though, that btf_value_type_id for such global data maps (ARRAY)
points to DATASEC type, which encodes full ELF name, so tools like
bpftool can take advantage of this fact to "recover" full original name
of the map. This is also the reason why for custom .data.* and .rodata.*
maps libbpf uses only their ELF names and doesn't prepend object name at
all.
Another downside of such approach is that it is not backwards compatible
and, among direct use of bpf_object__find_map_by_name() API, will break
any BPF skeleton generated using bpftool that was compiled with older
libbpf version.
Instead of causing all this pain, libbpf will still generate map name
using a combination of object name and ELF section name, but it will
allow looking such maps up by their natural names, which correspond to
their respective ELF section names. This means non-truncated ELF section
names longer than 15 characters are going to be expected and supported.
With such set up, we get the best of both worlds: leave small bits of
a clue about BPF application that instantiated such maps, as well as
making it easy for user apps to lookup such maps at runtime. In this
sense it closes corresponding libbpf 1.0 issue ([0]).
BPF skeletons will continue using full names for lookups.
[0] Closes: https://github.com/libbpf/libbpf/issues/275
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20211021014404.2635234-10-andrii@kernel.org
Add support for having multiple .rodata and .data data sections ([0]).
.rodata/.data are supported like the usual, but now also
.rodata.<whatever> and .data.<whatever> are also supported. Each such
section will get its own backing BPF_MAP_TYPE_ARRAY, just like
.rodata and .data.
Multiple .bss maps are not supported, as the whole '.bss' name is
confusing and might be deprecated soon, as well as user would need to
specify custom ELF section with SEC() attribute anyway, so might as well
stick to just .data.* and .rodata.* convention.
User-visible map name for such new maps is going to be just their ELF
section names.
[0] https://github.com/libbpf/libbpf/issues/274
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20211021014404.2635234-8-andrii@kernel.org
Remove internal libbpf assumption that there can be only one .rodata,
.data, and .bss map per BPF object. To achieve that, extend and
generalize the scheme that was used for keeping track of relocation ELF
sections. Now each ELF section has a temporary extra index that keeps
track of logical type of ELF section (relocations, data, read-only data,
BSS). Switch relocation to this scheme, as well as .rodata/.data/.bss
handling.
We don't yet allow multiple .rodata, .data, and .bss sections, but no
libbpf internal code makes an assumption that there can be only one of
each and thus they can be explicitly referenced by a single index. Next
patches will actually allow multiple .rodata and .data sections.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20211021014404.2635234-5-andrii@kernel.org
Minimize the usage of class-agnostic gelf_xxx() APIs from libelf. These
APIs require copying ELF data structures into local GElf_xxx structs and
have a more cumbersome API. BPF ELF file is defined to be always 64-bit
ELF object, even when intended to be run on 32-bit host architectures,
so there is no need to do class-agnostic conversions everywhere. BPF
static linker implementation within libbpf has been using Elf64-specific
types since initial implementation.
Add two simple helpers, elf_sym_by_idx() and elf_rel_by_idx(), for more
succinct direct access to ELF symbol and relocation records within ELF
data itself and switch all the GElf_xxx usage into Elf64_xxx
equivalents. The only remaining place within libbpf.c that's still using
gelf API is gelf_getclass(), as there doesn't seem to be a direct way to
get underlying ELF bitness.
No functional changes intended.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20211021014404.2635234-4-andrii@kernel.org
There isn't a good use case where anyone but libbpf itself needs to call
btf__finalize_data(). It was implemented for internal use and it's not
clear why it was made into public API in the first place. To function, it
requires active ELF data, which is stored inside bpf_object for the
duration of opening phase only. But the only BTF that needs bpf_object's
ELF is that bpf_object's BTF itself, which libbpf fixes up automatically
during bpf_object__open() operation anyways. There is no need for any
additional fix up and no reasonable scenario where it's useful and
appropriate.
Thus, btf__finalize_data() is just an API atavism and is better removed.
So this patch marks it as deprecated immediately (v0.6+) and moves the
code from btf.c into libbpf.c where it's used in the context of
bpf_object opening phase. Such code co-location allows to make code
structure more straightforward and remove bpf_object__section_size() and
bpf_object__variable_offset() internal helpers from libbpf_internal.h,
making them static. Their naming is also adjusted to not create
a wrong illusion that they are some sort of method of bpf_object. They
are internal helpers and are called appropriately.
This is part of libbpf 1.0 effort ([0]).
[0] Closes: https://github.com/libbpf/libbpf/issues/276
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20211021014404.2635234-2-andrii@kernel.org
Add a bulk copying api, btf__add_btf(), that speeds up and simplifies
appending entire contents of one BTF object to another one, taking care
of copying BTF type data, adjusting resulting BTF type IDs according to
their new locations in the destination BTF object, as well as copying
and deduplicating all the referenced strings and updating all the string
offsets in new BTF types as appropriate.
This API is intended to be used from tools that are generating and
otherwise manipulating BTFs generically, such as pahole. In pahole's
case, this API is useful for speeding up parallelized BTF encoding, as
it allows pahole to offload all the intricacies of BTF type copying to
libbpf and handle the parallelization aspects of the process.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Song Liu <songliubraving@fb.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Link: https://lore.kernel.org/bpf/20211006051107.17921-2-andrii@kernel.org
Update "sk_lookup/" definition to be a stand-alone type specifier,
with backwards-compatible prefix match logic in non-libbpf-1.0 mode.
Currently in selftests all the "sk_lookup/<whatever>" uses just use
<whatever> for duplicated unique name encoding, which is redundant as
BPF program's name (C function name) uniquely and descriptively
identifies the intended use for such BPF programs.
With libbpf's SEC_DEF("sk_lookup") definition updated, switch existing
sk_lookup programs to use "unqualified" SEC("sk_lookup") section names,
with no random text after it.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Dave Marchevsky <davemarchevsky@fb.com>
Link: https://lore.kernel.org/bpf/20210928161946.2512801-11-andrii@kernel.org
Implement strict ELF section name handling for BPF programs. It utilizes
`libbpf_set_strict_mode()` framework and adds new flag: LIBBPF_STRICT_SEC_NAME.
If this flag is set, libbpf will enforce exact section name matching for
a lot of program types that previously allowed just partial prefix
match. E.g., if previously SEC("xdp_whatever_i_want") was allowed, now
in strict mode only SEC("xdp") will be accepted, which makes SEC("")
definitions cleaner and more structured. SEC() now won't be used as yet
another way to uniquely encode BPF program identifier (for that
C function name is better and is guaranteed to be unique within
bpf_object). Now SEC() is strictly BPF program type and, depending on
program type, extra load/attach parameter specification.
Libbpf completely supports multiple BPF programs in the same ELF
section, so multiple BPF programs of the same type/specification easily
co-exist together within the same bpf_object scope.
Additionally, a new (for now internal) convention is introduced: section
name that can be a stand-alone exact BPF program type specificator, but
also could have extra parameters after '/' delimiter. An example of such
section is "struct_ops", which can be specified by itself, but also
allows to specify the intended operation to be attached to, e.g.,
"struct_ops/dctcp_init". Note, that "struct_ops_some_op" is not allowed.
Such section definition is specified as "struct_ops+".
This change is part of libbpf 1.0 effort ([0], [1]).
[0] Closes: https://github.com/libbpf/libbpf/issues/271
[1] https://github.com/libbpf/libbpf/wiki/Libbpf:-the-road-to-v1.0#stricter-and-more-uniform-bpf-program-section-name-sec-handling
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Dave Marchevsky <davemarchevsky@fb.com>
Link: https://lore.kernel.org/bpf/20210928161946.2512801-10-andrii@kernel.org
Complete SEC() table refactoring towards unified form by rewriting
BPF_APROG_SEC and BPF_EAPROG_SEC definitions with
SEC_DEF(SEC_ATTACHABLE_OPT) (for optional expected_attach_type) and
SEC_DEF(SEC_ATTACHABLE) (mandatory expected_attach_type), respectively.
Drop BPF_APROG_SEC, BPF_EAPROG_SEC, and BPF_PROG_SEC_IMPL macros after
that, leaving SEC_DEF() macro as the only one used.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Dave Marchevsky <davemarchevsky@fb.com>
Link: https://lore.kernel.org/bpf/20210928161946.2512801-9-andrii@kernel.org
Refactor ELF section handler definitions table to use a set of flags and
unified SEC_DEF() macro. This allows for more succinct and table-like
set of definitions, and allows to more easily extend the logic without
adding more verbosity (this is utilized in later patches in the series).
This approach is also making libbpf-internal program pre-load callback
not rely on bpf_sec_def definition, which demonstrates that future
pluggable ELF section handlers will be able to achieve similar level of
integration without libbpf having to expose extra types and APIs.
For starters, update SEC_DEF() definitions and make them more succinct.
Also convert BPF_PROG_SEC() and BPF_APROG_COMPAT() definitions to
a common SEC_DEF() use.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Dave Marchevsky <davemarchevsky@fb.com>
Link: https://lore.kernel.org/bpf/20210928161946.2512801-8-andrii@kernel.org
Move closer to not relying on bpf_sec_def internals that won't be part
of public API, when pluggable SEC() handlers will be allowed. Drop
pre-calculated prefix length, and in various helpers don't rely on this
prefix length availability. Also minimize reliance on knowing
bpf_sec_def's prefix for few places where section prefix shortcuts are
supported (e.g., tp vs tracepoint, raw_tp vs raw_tracepoint).
Given checking some string for having a given string-constant prefix is
such a common operation and so annoying to be done with pure C code, add
a small macro helper, str_has_pfx(), and reuse it throughout libbpf.c
where prefix comparison is performed. With __builtin_constant_p() it's
possible to have a convenient helper that checks some string for having
a given prefix, where prefix is either string literal (or compile-time
known string due to compiler optimization) or just a runtime string
pointer, which is quite convenient and saves a lot of typing and string
literal duplication.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Dave Marchevsky <davemarchevsky@fb.com>
Link: https://lore.kernel.org/bpf/20210928161946.2512801-7-andrii@kernel.org
Refactor internals of libbpf to allow adding custom SEC() handling logic
easily from outside of libbpf. To that effect, each SEC()-handling
registration sets mandatory program type/expected attach type for
a given prefix and can provide three callbacks called at different
points of BPF program lifetime:
- init callback for right after bpf_program is initialized and
prog_type/expected_attach_type is set. This happens during
bpf_object__open() step, close to the very end of constructing
bpf_object, so all the libbpf APIs for querying and updating
bpf_program properties should be available;
- pre-load callback is called right before BPF_PROG_LOAD command is
called in the kernel. This callbacks has ability to set both
bpf_program properties, as well as program load attributes, overriding
and augmenting the standard libbpf handling of them;
- optional auto-attach callback, which makes a given SEC() handler
support auto-attachment of a BPF program through bpf_program__attach()
API and/or BPF skeletons <skel>__attach() method.
Each callbacks gets a `long cookie` parameter passed in, which is
specified during SEC() handling. This can be used by callbacks to lookup
whatever additional information is necessary.
This is not yet completely ready to be exposed to the outside world,
mainly due to non-public nature of struct bpf_prog_load_params. Instead
of making it part of public API, we'll wait until the planned low-level
libbpf API improvements for BPF_PROG_LOAD and other typical bpf()
syscall APIs, at which point we'll have a public, probably OPTS-based,
way to fully specify BPF program load parameters, which will be used as
an interface for custom pre-load callbacks.
But this change itself is already a good first step to unify the BPF
program hanling logic even within the libbpf itself. As one example, all
the extra per-program type handling (sleepable bit, attach_btf_id
resolution, unsetting optional expected attach type) is now more obvious
and is gathered in one place.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Dave Marchevsky <davemarchevsky@fb.com>
Link: https://lore.kernel.org/bpf/20210928161946.2512801-6-andrii@kernel.org
Similarly to recently added legacy kprobe attach interface support
through tracefs, support attaching uprobes using the legacy interface if
host kernel doesn't support newer FD-based interface.
For uprobes event name consists of "libbpf_" prefix, PID, sanitized
binary path and offset within that binary. Structuraly the code is
aligned with kprobe logic refactoring in previous patch. struct
bpf_link_perf is re-used and all the same legacy_probe_name and
legacy_is_retprobe fields are used to ensure proper cleanup on
bpf_link__destroy().
Users should be aware, though, that on old kernels which don't support
FD-based interface for kprobe/uprobe attachment, if the application
crashes before bpf_link__destroy() is called, uprobe legacy
events will be left in tracefs. This is the same limitation as with
legacy kprobe interfaces.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210921210036.1545557-5-andrii@kernel.org
Refactor legacy kprobe handling code to follow the same logic as uprobe
legacy logic added in the next patchs:
- add append_to_file() helper that makes it simpler to work with
tracefs file-based interface for creating and deleting probes;
- move out probe/event name generation outside of the code that
adds/removes it, which simplifies bookkeeping significantly;
- change the probe name format to start with "libbpf_" prefix and
include offset within kernel function;
- switch 'unsigned long' to 'size_t' for specifying kprobe offsets,
which is consistent with how uprobes define that, simplifies
printf()-ing internally, and also avoids unnecessary complications on
architectures where sizeof(long) != sizeof(void *).
This patch also implicitly fixes the problem with invalid open() error
handling present in poke_kprobe_events(), which (the function) this
patch removes.
Fixes: ca304b40c20d ("libbpf: Introduce legacy kprobe events support")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210921210036.1545557-4-andrii@kernel.org
bpf_object_open_opts.attach_prog_fd makes a pretty strong assumption
that bpf_object contains either only single freplace BPF program or all
of BPF programs in BPF object are freplaces intended to replace
different subprograms of the same target BPF program. This seems both
a bit confusing, too assuming, and limiting.
We've had bpf_program__set_attach_target() API which allows more
fine-grained control over this, on a per-program level. As such, mark
open_opts.attach_prog_fd as deprecated starting from v0.7, so that we
have one more universal way of setting freplace targets. With previous
change to allow NULL attach_func_name argument, and especially combined
with BPF skeleton, arguable bpf_program__set_attach_target() is a more
convenient and explicit API as well.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210916015836.1248906-7-andrii@kernel.org
Allow to use bpf_program__set_attach_target to only set target attach
program FD, while letting libbpf to use target attach function name from
SEC() definition. This might be useful for some scenarios where
bpf_object contains multiple related freplace BPF programs intended to
replace different sub-programs in target BPF program. In such case all
programs will have the same attach_prog_fd, but different
attach_func_name. It's convenient to specify such target function names
declaratively in SEC() definitions, but attach_prog_fd is a dynamic
runtime setting.
To simplify such scenario, allow bpf_program__set_attach_target() to
delay BTF ID resolution till the BPF program load time by providing NULL
attach_func_name. In that case the behavior will be similar to using
bpf_object_open_opts.attach_prog_fd (which is marked deprecated since
v0.7), but has the benefit of allowing more control by user in what is
attached to what. Such setup allows having BPF programs attached to
different target attach_prog_fd with target functions still declaratively
recorded in BPF source code in SEC() definitions.
Selftests changes in the next patch should make this more obvious.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210916015836.1248906-5-andrii@kernel.org
Doing substring matches allows accidental new tests to be enabled,
when they are not supposed to be. E.g., whitelisting "xdp" allows new
"xdpwall" test on 5.5.0, which wasn't supposed to happen.
Cc: Yucong Sun <fallentree@fb.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
There is a problem in bpf-next tree which causes get_stack_raw_tp and
few other selftests to produce tons of kernel warnings, timing out and
failing CI test runs. Blacklist until bpf tree, which has a fix, is
merged into bpf-next.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Remove almost all the code that explicitly iterated BPF program section
definitions in favor of using find_sec_def(). The only remaining user of
section_defs is libbpf_get_type_names that has to iterate all of them to
construct its result.
Having one internal API entry point for section definitions will
simplify further refactorings around libbpf's program section
definitions parsing.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20210914014733.2768-5-andrii@kernel.org
Remove the need to explicitly pass bpf_sec_def for auto-attachable BPF
programs, as it is already recorded at bpf_object__open() time for all
recognized type of BPF programs. This further reduces number of explicit
calls to find_sec_def(), simplifying further refactorings.
No functional changes are done by this patch.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20210914014733.2768-4-andrii@kernel.org
Refactor bpf_object__open() sequencing to perform BPF program type
detection based on SEC() definitions before we get to relocations
collection. This allows to have more information about BPF program by
the time we get to, say, struct_ops relocation gathering. This,
subsequently, simplifies struct_ops logic and removes the need to
perform extra find_sec_def() resolution.
With this patch libbpf will require all struct_ops BPF programs to be
marked with SEC("struct_ops") or SEC("struct_ops/xxx") annotations.
Real-world applications are already doing that through something like
selftests's BPF_STRUCT_OPS() macro. This change streamlines libbpf's
internal handling of SEC() definitions and is in the sprit of
upcoming libbpf-1.0 section strictness changes ([0]).
[0] https://github.com/libbpf/libbpf/wiki/Libbpf:-the-road-to-v1.0#stricter-and-more-uniform-bpf-program-section-name-sec-handling
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20210914014733.2768-3-andrii@kernel.org
Turn previously auto-generated libbpf_version.h header into a normal
header file. This prevents various tricky Makefile integration issues,
simplifies the overall build process, but also allows to further extend
it with some more versioning-related APIs in the future.
To prevent accidental out-of-sync versions as defined by libbpf.map and
libbpf_version.h, Makefile checks their consistency at build time.
Simultaneously with this change bump libbpf.map to v0.6.
Also undo adding libbpf's output directory into include path for
kernel/bpf/preload, bpftool, and resolve_btfids, which is not necessary
because libbpf_version.h is just a normal header like any other.
Fixes: 0b46b7550560 ("libbpf: Add LIBBPF_DEPRECATED_SINCE macro for scheduling API deprecations")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210913222309.3220849-1-andrii@kernel.org
Use this list of enabled tests as a whitelist, so that we don't have to
keep updating BLACKLIST-5.5.0 anymore. I'll keep BLACKLIST-5.5.0 for
now, because it serves as a nice historic log of which tests depend on
which kernels.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
When attaching to uprobes through perf subsystem, it's possible to specify
offset of a so-called USDT semaphore, which is just a reference counted u16,
used by kernel to keep track of how many tracers are attached to a given
location. Support for this feature was added in [0], so just wire this through
uprobe_opts. This is important to enable implementing USDT attachment and
tracing through libbpf's bpf_program__attach_uprobe_opts() API.
[0] a6ca88b241d5 ("trace_uprobe: support reference counter in fd-based uprobe")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210815070609.987780-16-andrii@kernel.org
Wire through bpf_cookie for all attach APIs that use perf_event_open under the
hood:
- for kprobes, extend existing bpf_kprobe_opts with bpf_cookie field;
- for perf_event, uprobe, and tracepoint APIs, add their _opts variants and
pass bpf_cookie through opts.
For kernel that don't support BPF_LINK_CREATE for perf_events, and thus
bpf_cookie is not supported either, return error and log warning for user.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210815070609.987780-12-andrii@kernel.org
Add ability to specify bpf_cookie value when creating BPF perf link with
bpf_link_create() low-level API.
Given BPF_LINK_CREATE command is growing and keeps getting new fields that are
specific to the type of BPF_LINK, extend libbpf side of bpf_link_create() API
and corresponding OPTS struct to accomodate such changes. Add extra checks to
prevent using incompatible/unexpected combinations of fields.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210815070609.987780-11-andrii@kernel.org
Detect kernel support for BPF perf link and prefer it when attaching to
perf_event, tracepoint, kprobe/uprobe. Underlying perf_event FD will be kept
open until BPF link is destroyed, at which point both perf_event FD and BPF
link FD will be closed.
This preserves current behavior in which perf_event FD is open for the
duration of bpf_link's lifetime and user is able to "disconnect" bpf_link from
underlying FD (with bpf_link__disconnect()), so that bpf_link__destroy()
doesn't close underlying perf_event FD.When BPF perf link is used, disconnect
will keep both perf_event and bpf_link FDs open, so it will be up to
(advanced) user to close them. This approach is demonstrated in bpf_cookie.c
selftests, added in this patch set.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210815070609.987780-10-andrii@kernel.org
bpf_link->destroy() isn't used by any code, so remove it. Instead, add ability
to override deallocation procedure, with default doing plain free(link). This
is necessary for cases when we want to "subclass" struct bpf_link to keep
extra information, as is the case in the next patch adding struct
bpf_link_perf.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210815070609.987780-9-andrii@kernel.org
Add new BPF helper, bpf_get_attach_cookie(), which can be used by BPF programs
to get access to a user-provided bpf_cookie value, specified during BPF
program attachment (BPF link creation) time.
Naming is hard, though. With the concept being named "BPF cookie", I've
considered calling the helper:
- bpf_get_cookie() -- seems too unspecific and easily mistaken with socket
cookie;
- bpf_get_bpf_cookie() -- too much tautology;
- bpf_get_link_cookie() -- would be ok, but while we create a BPF link to
attach BPF program to BPF hook, it's still an "attachment" and the
bpf_cookie is associated with BPF program attachment to a hook, not a BPF
link itself. Technically, we could support bpf_cookie with old-style
cgroup programs.So I ultimately rejected it in favor of
bpf_get_attach_cookie().
Currently all perf_event-backed BPF program types support
bpf_get_attach_cookie() helper. Follow-up patches will add support for
fentry/fexit programs as well.
While at it, mark bpf_tracing_func_proto() as static to make it obvious that
it's only used from within the kernel/trace/bpf_trace.c.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210815070609.987780-7-andrii@kernel.org
Add ability for users to specify custom u64 value (bpf_cookie) when creating
BPF link for perf_event-backed BPF programs (kprobe/uprobe, perf_event,
tracepoints).
This is useful for cases when the same BPF program is used for attaching and
processing invocation of different tracepoints/kprobes/uprobes in a generic
fashion, but such that each invocation is distinguished from each other (e.g.,
BPF program can look up additional information associated with a specific
kernel function without having to rely on function IP lookups). This enables
new use cases to be implemented simply and efficiently that previously were
possible only through code generation (and thus multiple instances of almost
identical BPF program) or compilation at runtime (BCC-style) on target hosts
(even more expensive resource-wise). For uprobes it is not even possible in
some cases to know function IP before hand (e.g., when attaching to shared
library without PID filtering, in which case base load address is not known
for a library).
This is done by storing u64 bpf_cookie in struct bpf_prog_array_item,
corresponding to each attached and run BPF program. Given cgroup BPF programs
already use two 8-byte pointers for their needs and cgroup BPF programs don't
have (yet?) support for bpf_cookie, reuse that space through union of
cgroup_storage and new bpf_cookie field.
Make it available to kprobe/tracepoint BPF programs through bpf_trace_run_ctx.
This is set by BPF_PROG_RUN_ARRAY, used by kprobe/uprobe/tracepoint BPF
program execution code, which luckily is now also split from
BPF_PROG_RUN_ARRAY_CG. This run context will be utilized by a new BPF helper
giving access to this user-provided cookie value from inside a BPF program.
Generic perf_event BPF programs will access this value from perf_event itself
through passed in BPF program context.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/bpf/20210815070609.987780-6-andrii@kernel.org
Introduce a new type of BPF link - BPF perf link. This brings perf_event-based
BPF program attachments (perf_event, tracepoints, kprobes, and uprobes) into
the common BPF link infrastructure, allowing to list all active perf_event
based attachments, auto-detaching BPF program from perf_event when link's FD
is closed, get generic BPF link fdinfo/get_info functionality.
BPF_LINK_CREATE command expects perf_event's FD as target_fd. No extra flags
are currently supported.
Force-detaching and atomic BPF program updates are not yet implemented, but
with perf_event-based BPF links we now have common framework for this without
the need to extend ioctl()-based perf_event interface.
One interesting consideration is a new value for bpf_attach_type, which
BPF_LINK_CREATE command expects. Generally, it's either 1-to-1 mapping from
bpf_attach_type to bpf_prog_type, or many-to-1 mapping from a subset of
bpf_attach_types to one bpf_prog_type (e.g., see BPF_PROG_TYPE_SK_SKB or
BPF_PROG_TYPE_CGROUP_SOCK). In this case, though, we have three different
program types (KPROBE, TRACEPOINT, PERF_EVENT) using the same perf_event-based
mechanism, so it's many bpf_prog_types to one bpf_attach_type. I chose to
define a single BPF_PERF_EVENT attach type for all of them and adjust
link_create()'s logic for checking correspondence between attach type and
program type.
The alternative would be to define three new attach types (e.g., BPF_KPROBE,
BPF_TRACEPOINT, and BPF_PERF_EVENT), but that seemed like unnecessary overkill
and BPF_KPROBE will cause naming conflicts with BPF_KPROBE() macro, defined by
libbpf. I chose to not do this to avoid unnecessary proliferation of
bpf_attach_type enum values and not have to deal with naming conflicts.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/bpf/20210815070609.987780-5-andrii@kernel.org
Kernel docs from Documentation/bpf/libbpf go straight to docs/ under libbpf.
Also ignore libbpf-only parts of docs subdir.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Only keep stderr output in case of errors for kernel and selftests builds.
Having a multi-thousand-line output isn't useful and slows down Github
Actions' log view UI.
Also quiet down wget's "progress bar" output. While at the same time see some
totals from tar, just for the fun of it.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Andrii Nakryiko