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strerror() expects a positive errno, however variable err will never be
positive when an error occurs. This causes bpftool to output too many
"unknown error", even a simple "file not exist" error can not get an
accurate message.
This patch fixed all "strerror(err)" patterns in bpftool.
Specially in btf.c#L823, hashmap__append() is an internal function of
libbpf and will not change errno, so there's a little difference.
Some libbpf_get_error() calls are kept for return values.
Changes since v1: https://lore.kernel.org/bpf/SY4P282MB1084B61CD8671DFA395AA8579D539@SY4P282MB1084.AUSP282.PROD.OUTLOOK.COM/
Check directly for NULL values instead of calling libbpf_get_error().
Signed-off-by: Tianyi Liu <i.pear@outlook.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Link: https://lore.kernel.org/bpf/SY4P282MB1084AD9CD84A920F08DF83E29D549@SY4P282MB1084.AUSP282.PROD.OUTLOOK.COM
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A skeleton generated by bpftool previously contained a return followed
by an expression in OBJ_NAME__detach(), which has return type void. This
did not hurt, the bpf_object__detach_skeleton() called there returns
void itself anyway, but led to a warning when compiling with e.g.
-pedantic.
Signed-off-by: Jörn-Thorben Hinz <jthinz@mailbox.tu-berlin.de>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Link: https://lore.kernel.org/bpf/20220726133203.514087-1-jthinz@mailbox.tu-berlin.de
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This change adjusts bpftool's type marking logic, as used in conjunction
with TYPE_EXISTS relocations, to correctly recognize and handle the
RESTRICT BTF kind.
Suggested-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Müller <deso@posteo.net>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Quentin Monnet <quentin@isovalent.com>
Link: https://lore.kernel.org/bpf/20220623212205.2805002-1-deso@posteo.net/T/#m4c75205145701762a4b398e0cdb911d5b5305ffc
Link: https://lore.kernel.org/bpf/20220706212855.1700615-2-deso@posteo.net
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bpftool needs to know about the newly introduced BPF_CORE_TYPE_MATCHES
relocation for its 'gen min_core_btf' command to work properly in the
present of this relocation.
Specifically, we need to make sure to mark types and fields so that they
are present in the minimized BTF for "type match" checks to work out.
However, contrary to the existing btfgen_record_field_relo, we need to
rely on the BTF -- and not the spec -- to find fields. With this change
we handle this new variant correctly. The functionality will be tested
with follow on changes to BPF selftests, which already run against a
minimized BTF created with bpftool.
Signed-off-by: Daniel Müller <deso@posteo.net>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Quentin Monnet <quentin@isovalent.com>
Link: https://lore.kernel.org/bpf/20220628160127.607834-3-deso@posteo.net
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Add BTF_KIND_ENUM64 support.
For example, the following enum is defined in uapi bpf.h.
$ cat core.c
enum A {
BPF_F_INDEX_MASK = 0xffffffffULL,
BPF_F_CURRENT_CPU = BPF_F_INDEX_MASK,
BPF_F_CTXLEN_MASK = (0xfffffULL << 32),
} g;
Compiled with
clang -target bpf -O2 -g -c core.c
Using bpftool to dump types and generate format C file:
$ bpftool btf dump file core.o
...
[1] ENUM64 'A' encoding=UNSIGNED size=8 vlen=3
'BPF_F_INDEX_MASK' val=4294967295ULL
'BPF_F_CURRENT_CPU' val=4294967295ULL
'BPF_F_CTXLEN_MASK' val=4503595332403200ULL
$ bpftool btf dump file core.o format c
...
enum A {
BPF_F_INDEX_MASK = 4294967295ULL,
BPF_F_CURRENT_CPU = 4294967295ULL,
BPF_F_CTXLEN_MASK = 4503595332403200ULL,
};
...
Note that for raw btf output, the encoding (UNSIGNED or SIGNED)
is printed out as well. The 64bit value is also represented properly
in BTF and C dump.
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/r/20220607062652.3722649-1-yhs@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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bpf_object__btf() can return a NULL value. If bpf_object__btf returns
null, do not progress through codegen_asserts(). This avoids a null ptr
dereference at the call btf__type_cnt() in the function find_type_for_map()
Signed-off-by: Michael Mullin <masmullin@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220523194917.igkgorco42537arb@jup
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bpf_link_get_from_fd currently returns a NULL fd for LSM programs.
LSM programs are similar to tracing programs and can also use
skel_raw_tracepoint_open.
Signed-off-by: KP Singh <kpsingh@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20220509214905.3754984-1-kpsingh@kernel.org
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Most code generators declare its name so did this for bfptool.
Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220509090247.5457-1-jasowang@redhat.com
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Andrii noticed that since f97b8b9bd630 ("bpftool: Fix a bug in subskeleton
code generation") the subskeleton code allows bpf_object__destroy_subskeleton
to overwrite the errno that subskeleton__open would return with. While this
is not currently an issue, let's make it future-proof.
This patch explicitly tracks err in subskeleton__open and skeleton__create
(i.e. calloc failure is explicitly ENOMEM) and ensures that errno is -err on
the error return path. The skeleton code had to be changed since maps and
progs codegen is shared with subskeletons.
Fixes: f97b8b9bd630 ("bpftool: Fix a bug in subskeleton code generation")
Signed-off-by: Delyan Kratunov <delyank@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/3b6bfbb770c79ae64d8de26c1c1bd9d53a4b85f8.camel@fb.com
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Arnaldo reported perf compilation fail with:
$ make -k BUILD_BPF_SKEL=1 CORESIGHT=1 PYTHON=python3
...
In file included from util/bpf_counter.c:28:
/tmp/build/perf//util/bpf_skel/bperf_leader.skel.h: In function ‘bperf_leader_bpf__assert’:
/tmp/build/perf//util/bpf_skel/bperf_leader.skel.h:351:51: error: unused parameter ‘s’ [-Werror=unused-parameter]
351 | bperf_leader_bpf__assert(struct bperf_leader_bpf *s)
| ~~~~~~~~~~~~~~~~~~~~~~~~~^
cc1: all warnings being treated as errors
If there's nothing to generate in the new assert function,
we will get unused 's' warn/error, adding 'unused' attribute to it.
Fixes: 08d4dba6ae77 ("bpftool: Bpf skeletons assert type sizes")
Reported-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Link: https://lore.kernel.org/bpf/20220328083703.2880079-1-jolsa@kernel.org
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Compiled with clang by adding LLVM=1 both kernel and selftests/bpf
build, I hit the following compilation error:
In file included from /.../tools/testing/selftests/bpf/prog_tests/subskeleton.c:6:
./test_subskeleton_lib.subskel.h:168:6: error: variable 'err' is used uninitialized whenever
'if' condition is true [-Werror,-Wsometimes-uninitialized]
if (!s->progs)
^~~~~~~~~
./test_subskeleton_lib.subskel.h:181:11: note: uninitialized use occurs here
errno = -err;
^~~
./test_subskeleton_lib.subskel.h:168:2: note: remove the 'if' if its condition is always false
if (!s->progs)
^~~~~~~~~~~~~~
The compilation error is triggered by the following code
...
int err;
obj = (struct test_subskeleton_lib *)calloc(1, sizeof(*obj));
if (!obj) {
errno = ENOMEM;
goto err;
}
...
err:
test_subskeleton_lib__destroy(obj);
errno = -err;
...
in test_subskeleton_lib__open(). The 'err' is not initialized, yet it
is used in 'errno = -err' later.
The fix is to remove 'errno = -err' since errno has been set properly
in all incoming branches.
Fixes: 00389c58ffe9 ("bpftool: Add support for subskeletons")
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20220320032009.3106133-1-yhs@fb.com
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Subskeletons are headers which require an already loaded program to
operate.
For example, when a BPF library is linked into a larger BPF object file,
the library userspace needs a way to access its own global variables
without requiring knowledge about the larger program at build time.
As a result, subskeletons require a loaded bpf_object to open().
Further, they find their own symbols in the larger program by
walking BTF type data at run time.
At this time, programs, maps, and globals are supported through
non-owning pointers.
Signed-off-by: Delyan Kratunov <delyank@fb.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/ca8a48b4841c72d285ecce82371bef4a899756cb.1647473511.git.delyank@fb.com
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When emitting type declarations in skeletons, bpftool will now also emit
static assertions on the size of the data/bss/rodata/etc fields. This
ensures that in situations where userspace and kernel types have the same
name but differ in size we do not silently produce incorrect results but
instead break the build.
This was reported in [1] and as expected the repro in [2] fails to build
on the new size assert after this change.
[1]: Closes: https://github.com/libbpf/libbpf/issues/433
[2]: https://github.com/fuweid/iovisor-bcc-pr-3777
Signed-off-by: Delyan Kratunov <delyank@fb.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Tested-by: Hengqi Chen <hengqi.chen@gmail.com>
Acked-by: Hengqi Chen <hengqi.chen@gmail.com>
Link: https://lore.kernel.org/bpf/f562455d7b3cf338e59a7976f4690ec5a0057f7f.camel@fb.com
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Mark C++-specific T::open() and other methods as static inline to avoid
symbol redefinition when multiple files use the same skeleton header in
an application.
Fixes: bb8ffe61ea45 ("bpftool: Add C++-specific open/load/etc skeleton wrappers")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20220216233540.216642-1-andrii@kernel.org
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The last part of the BTFGen algorithm is to create a new BTF object with
all the types that were recorded in the previous steps.
This function performs two different steps:
1. Add the types to the new BTF object by using btf__add_type(). Some
special logic around struct and unions is implemented to only add the
members that are really used in the field-based relocations. The type
ID on the new and old BTF objects is stored on a map.
2. Fix all the type IDs on the new BTF object by using the IDs saved in
the previous step.
Signed-off-by: Mauricio Vásquez <mauricio@kinvolk.io>
Signed-off-by: Rafael David Tinoco <rafael.tinoco@aquasec.com>
Signed-off-by: Lorenzo Fontana <lorenzo.fontana@elastic.co>
Signed-off-by: Leonardo Di Donato <leonardo.didonato@elastic.co>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220215225856.671072-6-mauricio@kinvolk.io
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This commit implements the logic for the gen min_core_btf command.
Specifically, it implements the following functions:
- minimize_btf(): receives the path of a source and destination BTF
files and a list of BPF objects. This function records the relocations
for all objects and then generates the BTF file by calling
btfgen_get_btf() (implemented in the following commit).
- btfgen_record_obj(): loads the BTF and BTF.ext sections of the BPF
objects and loops through all CO-RE relocations. It uses
bpf_core_calc_relo_insn() from libbpf and passes the target spec to
btfgen_record_reloc(), that calls one of the following functions
depending on the relocation kind.
- btfgen_record_field_relo(): uses the target specification to mark all
the types that are involved in a field-based CO-RE relocation. In this
case types resolved and marked recursively using btfgen_mark_type().
Only the struct and union members (and their types) involved in the
relocation are marked to optimize the size of the generated BTF file.
- btfgen_record_type_relo(): marks the types involved in a type-based
CO-RE relocation. In this case no members for the struct and union types
are marked as libbpf doesn't use them while performing this kind of
relocation. Pointed types are marked as they are used by libbpf in this
case.
- btfgen_record_enumval_relo(): marks the whole enum type for enum-based
relocations.
Signed-off-by: Mauricio Vásquez <mauricio@kinvolk.io>
Signed-off-by: Rafael David Tinoco <rafael.tinoco@aquasec.com>
Signed-off-by: Lorenzo Fontana <lorenzo.fontana@elastic.co>
Signed-off-by: Leonardo Di Donato <leonardo.didonato@elastic.co>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220215225856.671072-5-mauricio@kinvolk.io
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This command is implemented under the "gen" command in bpftool and the
syntax is the following:
$ bpftool gen min_core_btf INPUT OUTPUT OBJECT [OBJECT...]
INPUT is the file that contains all the BTF types for a kernel and
OUTPUT is the path of the minimize BTF file that will be created with
only the types needed by the objects.
Signed-off-by: Mauricio Vásquez <mauricio@kinvolk.io>
Signed-off-by: Rafael David Tinoco <rafael.tinoco@aquasec.com>
Signed-off-by: Lorenzo Fontana <lorenzo.fontana@elastic.co>
Signed-off-by: Leonardo Di Donato <leonardo.didonato@elastic.co>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220215225856.671072-4-mauricio@kinvolk.io
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Add C++-specific static methods for code-generated BPF skeleton for each
skeleton operation: open, open_opts, open_and_load, load, attach,
detach, destroy, and elf_bytes. This is to facilitate easier C++
templating on top of pure C BPF skeleton.
In C, open/load/destroy/etc "methods" are of the form
<skeleton_name>__<method>() to avoid name collision with similar
"methods" of other skeletons withint the same application. This works
well, but is very inconvenient for C++ applications that would like to
write generic (templated) wrappers around BPF skeleton to fit in with
C++ code base and take advantage of destructors and other convenient C++
constructs.
This patch makes it easier to build such generic templated wrappers by
additionally defining C++ static methods for skeleton's struct with
fixed names. This allows to refer to, say, open method as `T::open()`
instead of having to somehow generate `T__open()` function call.
Next patch adds an example template to test_cpp selftest to demonstrate
how it's possible to have all the operations wrapped in a generic
Skeleton<my_skeleton> type without explicitly passing function references.
An example of generated declaration section without %1$s placeholders:
#ifdef __cplusplus
static struct test_attach_probe *open(const struct bpf_object_open_opts *opts = nullptr);
static struct test_attach_probe *open_and_load();
static int load(struct test_attach_probe *skel);
static int attach(struct test_attach_probe *skel);
static void detach(struct test_attach_probe *skel);
static void destroy(struct test_attach_probe *skel);
static const void *elf_bytes(size_t *sz);
#endif /* __cplusplus */
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20220212055733.539056-2-andrii@kernel.org
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Generealize light skeleton by hiding mmap details in skel_internal.h
In this form generated lskel.h is usable both by user space and by the kernel.
Note that previously #include <bpf/bpf.h> was in *.lskel.h file.
To avoid #ifdef-s in a generated lskel.h the include of bpf.h is moved
to skel_internal.h, but skel_internal.h is also used by gen_loader.c
which is part of libbpf. Therefore skel_internal.h does #include "bpf.h"
in case of user space, so gen_loader.c and lskel.h have necessary definitions.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220209232001.27490-4-alexei.starovoitov@gmail.com
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Open code raw_tracepoint_open and link_create used by light skeleton
to be able to avoid full libbpf eventually.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20220131220528.98088-4-alexei.starovoitov@gmail.com
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bpf iterator programs should use bpf_link_create to attach instead of
bpf_raw_tracepoint_open like other tracing programs.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20220131220528.98088-2-alexei.starovoitov@gmail.com
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Use bpf_program__type() instead of discouraged bpf_program__get_type().
Also switch to bpf_map__set_max_entries() instead of bpf_map__resize().
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20220124194254.2051434-5-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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libbpf bpf_map__def() API is being deprecated, replace bpftool's
usage with the appropriate getters and setters
Signed-off-by: Christy Lee <christylee@fb.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220108004218.355761-3-christylee@fb.com
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After `bpftool gen skeleton`, the ${bpf_app}.skel.h will provide that
${bpf_app_name}__open helper to load bpf. If there is some error
like ENOMEM, the ${bpf_app_name}__open will rollback(free) the allocated
object, including `bpf_object_skeleton`.
Since the ${bpf_app_name}__create_skeleton set the obj->skeleton first
and not rollback it when error, it will cause double-free in
${bpf_app_name}__destory at ${bpf_app_name}__open. Therefore, we should
set the obj->skeleton before return 0;
Fixes: 5dc7a8b21144 ("bpftool, selftests/bpf: Embed object file inside skeleton")
Signed-off-by: Wei Fu <fuweid89@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220108084008.1053111-1-fuweid89@gmail.com
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Switch all the uses of to-be-deprecated bpf_object__load_xattr() into
a simple bpf_object__load() calls with optional log_level passed through
open_opts.kernel_log_level, if -d option is specified.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211209193840.1248570-13-andrii@kernel.org
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Currently, LIBBPF_STRICT_ALL mode is enabled by default for
bpftool which means on error cases, some libbpf APIs would
return NULL pointers. This makes IS_ERR check failed to detect
such cases and result in segfault error. Use libbpf_get_error()
instead like we do in libbpf itself.
Signed-off-by: Hengqi Chen <hengqi.chen@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211115012436.3143318-1-hengqi.chen@gmail.com
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Use v1.0-compatible variants of btf_dump and perf_buffer "constructors".
This is also a demonstration of reusing struct perf_buffer_raw_opts as
OPTS-style option struct for new perf_buffer__new_raw() API.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211111053624.190580-10-andrii@kernel.org
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Replace the call to btf__get_nr_types with new API btf__type_cnt.
The old API will be deprecated in libbpf v0.7+. No functionality
change.
Signed-off-by: Hengqi Chen <hengqi.chen@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211022130623.1548429-5-hengqi.chen@gmail.com
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It can happen that some data sections (e.g., .rodata.cst16, containing
compiler populated string constants) won't have a corresponding BTF
DATASEC type. Now that libbpf supports .rodata.* and .data.* sections,
situation like that will cause invalid BPF skeleton to be generated that
won't compile successfully, as some parts of skeleton would assume
memory-mapped struct definitions for each special data section.
Fix this by generating empty struct definitions for such 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/20211021014404.2635234-7-andrii@kernel.org
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Remove the assumption about only single instance of each of .rodata and
.data internal maps. Nothing changes for '.rodata' and '.data' maps, but new
'.rodata.something' map will get 'rodata_something' section in BPF
skeleton for them (as well as having struct bpf_map * field in maps
section with the same field name).
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/20211021014404.2635234-6-andrii@kernel.org
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It seems that the header file was never necessary to compile bpftool,
and it is not part of the headers exported from libbpf. Let's remove the
includes from prog.c and gen.c.
Fixes: d510296d331a ("bpftool: Use syscall/loader program in "prog load" and "gen skeleton" command.")
Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211007194438.34443-3-quentin@isovalent.com
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"?:" is a GNU C extension, some environment has warning flags for its
use, or even prohibit it directly. This patch avoid triggering these
problems by simply expand it to its full form, no functionality change.
Signed-off-by: Yucong Sun <fallentree@fb.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210928184221.1545079-1-fallentree@fb.com
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This adds a skeleton method X__elf_bytes() which returns the binary data of
the compiled and embedded BPF object file. It additionally sets the size of
the return data to the provided size_t pointer argument.
The assignment to s->data is cast to void * to ensure no warning is issued if
compiled with a previous version of libbpf where the bpf_object_skeleton field
is void * instead of const void *
Signed-off-by: Matt Smith <alastorze@fb.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210901194439.3853238-3-alastorze@fb.com
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The -L|--use-loader option for using loader programs when loading, or
when generating a skeleton, did not have any documentation or bash
completion. Same thing goes for -B|--base-btf, used to pass a path to a
base BTF object for split BTF such as BTF for kernel modules.
This patch documents and adds bash completion for those options.
Fixes: 75fa1777694c ("tools/bpftool: Add bpftool support for split BTF")
Fixes: d510296d331a ("bpftool: Use syscall/loader program in "prog load" and "gen skeleton" command.")
Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210730215435.7095-7-quentin@isovalent.com
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All bpftool commands support the options for JSON output and debug from
libbpf. In addition, some commands support additional options
corresponding to specific use cases.
The list of options described in the man pages for the different
commands are not always accurate. The messages for interactive help are
mostly limited to HELP_SPEC_OPTIONS, and are even less representative of
the actual set of options supported for the commands.
Let's update the lists:
- HELP_SPEC_OPTIONS is modified to contain the "default" options (JSON
and debug), and to be extensible (no ending curly bracket).
- All commands use HELP_SPEC_OPTIONS in their help message, and then
complete the list with their specific options.
- The lists of options in the man pages are updated.
- The formatting of the list for bpftool.rst is adjusted to match
formatting for the other man pages. This is for consistency, and also
because it will be helpful in a future patch to automatically check
that the files are synchronised.
Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210730215435.7095-5-quentin@isovalent.com
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Follow libbpf's error handling conventions and pass through errors and errno
properly. Skeleton code always returned NULL on errors (not ERR_PTR(err)), so
there are no backwards compatibility concerns. But now we also set errno
properly, so it's possible to distinguish different reasons for failure, if
necessary.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/20210525035935.1461796-6-andrii@kernel.org
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Add -L flag to bpftool to use libbpf gen_trace facility and syscall/loader program
for skeleton generation and program loading.
"bpftool gen skeleton -L" command will generate a "light skeleton" or "loader skeleton"
that is similar to existing skeleton, but has one major difference:
$ bpftool gen skeleton lsm.o > lsm.skel.h
$ bpftool gen skeleton -L lsm.o > lsm.lskel.h
$ diff lsm.skel.h lsm.lskel.h
@@ -5,34 +4,34 @@
#define __LSM_SKEL_H__
#include <stdlib.h>
-#include <bpf/libbpf.h>
+#include <bpf/bpf.h>
The light skeleton does not use majority of libbpf infrastructure.
It doesn't need libelf. It doesn't parse .o file.
It only needs few sys_bpf wrappers. All of them are in bpf/bpf.h file.
In future libbpf/bpf.c can be inlined into bpf.h, so not even libbpf.a would be
needed to work with light skeleton.
"bpftool prog load -L file.o" command is introduced for debugging of syscall/loader
program generation. Just like the same command without -L it will try to load
the programs from file.o into the kernel. It won't even try to pin them.
"bpftool prog load -L -d file.o" command will provide additional debug messages
on how syscall/loader program was generated.
Also the execution of syscall/loader program will use bpf_trace_printk() for
each step of loading BTF, creating maps, and loading programs.
The user can do "cat /.../trace_pipe" for further debug.
An example of fexit_sleep.lskel.h generated from progs/fexit_sleep.c:
struct fexit_sleep {
struct bpf_loader_ctx ctx;
struct {
struct bpf_map_desc bss;
} maps;
struct {
struct bpf_prog_desc nanosleep_fentry;
struct bpf_prog_desc nanosleep_fexit;
} progs;
struct {
int nanosleep_fentry_fd;
int nanosleep_fexit_fd;
} links;
struct fexit_sleep__bss {
int pid;
int fentry_cnt;
int fexit_cnt;
} *bss;
};
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210514003623.28033-18-alexei.starovoitov@gmail.com
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As discussed in [0], stop emitting static variables in BPF skeletons to avoid
issues with name-conflicting static variables across multiple
statically-linked BPF object files.
Users using static variables to pass data between BPF programs and user-space
should do a trivial one-time switch according to the following simple rules:
- read-only `static volatile const` variables should be converted to
`volatile const`;
- read/write `static volatile` variables should just drop `static volatile`
modifiers to become global variables/symbols. To better handle older Clang
versions, such newly converted global variables should be explicitly
initialized with a specific value or `= 0`/`= {}`, whichever is
appropriate.
[0] https://lore.kernel.org/bpf/CAEf4BzZo7_r-hsNvJt3w3kyrmmBJj7ghGY8+k4nvKF0KLjma=w@mail.gmail.com/T/#m664d4b0d6b31ac8b2669360e0fc2d6962e9f5ec1
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210507054119.270888-5-andrii@kernel.org
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For better future extensibility add per-file linker options. Currently
the set of available options is empty. This changes bpf_linker__add_file()
API, but it's not a breaking change as bpf_linker APIs hasn't been released
yet.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210507054119.270888-3-andrii@kernel.org
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Similarly to .rodata, strip any const/volatile/restrict modifiers when
generating BPF skeleton. They are not helpful and actually just get in the way.
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/20210507054119.270888-2-andrii@kernel.org
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Add `bpftool gen object <output-file> <input_file>...` command to statically
link multiple BPF ELF object files into a single output BPF ELF object file.
This patch also updates bash completions and man page. Man page gets a short
section on `gen object` command, but also updates the skeleton example to show
off workflow for BPF application with two .bpf.c files, compiled individually
with Clang, then resulting object files are linked together with `gen object`,
and then final object file is used to generate usable BPF skeleton. This
should help new users understand realistic workflow w.r.t. compiling
mutli-file BPF application.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Link: https://lore.kernel.org/bpf/20210318194036.3521577-10-andrii@kernel.org
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Add optional name OBJECT_NAME parameter to `gen skeleton` command to override
default object name, normally derived from input file name. This allows much
more flexibility during build time.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210318194036.3521577-9-andrii@kernel.org
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Most netlink-related functions were unique to bpftool usage, so I moved them
into net.c. Few functions are still used by both bpftool and libbpf itself
internally, so I've copy-pasted them (libbpf_nl_get_link,
libbpf_netlink_open). It's a bit of duplication of code, but better separation
of libbpf as a library with public API and bpftool, relying on unexposed
functions in libbpf.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200819013607.3607269-3-andriin@fb.com
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The comment in the code describes this in good details. Generate such a memory
layout that would work both on 32-bit and 64-bit architectures for user-space.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200813204945.1020225-9-andriin@fb.com
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Seems like C++17 standard mode doesn't recognize typeof() anymore. This can
be tested by compiling test_cpp test with -std=c++17 or -std=c++1z options.
The use of typeof in skeleton generated code is unnecessary, all types are
well-known at the time of code generation, so remove all typeof()'s to make
skeleton code more future-proof when interacting with C++ compilers.
Fixes: 985ead416df3 ("bpftool: Add skeleton codegen command")
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20200812025907.1371956-1-andriin@fb.com
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Fix pass 0 to PTR_ERR, also dump more err info using
libbpf_strerror.
Fixes: 5dc7a8b21144 ("bpftool, selftests/bpf: Embed object file inside skeleton")
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Link: https://lore.kernel.org/bpf/20200717123059.29624-1-yuehaibing@huawei.com
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Reliably remove all the type modifiers from read-only (.rodata) global
variable definitions, including cases of inner field const modifiers and
arrays of const values.
Also modify one of selftests to ensure that const volatile struct doesn't
prevent user-space from modifying .rodata variable.
Fixes: 985ead416df3 ("bpftool: Add skeleton codegen command")
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200713232409.3062144-3-andriin@fb.com
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Remove unnecessary check at the end of codegen() routine which makes codegen()
to always fail and exit bpftool with error code. Positive value of variable
n is not an indicator of a failure.
Fixes: 2c4779eff837 ("tools, bpftool: Exit on error in function codegen")
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Tobias Klauser <tklauser@distanz.ch>
Link: https://lore.kernel.org/bpf/20200612201603.680852-1-andriin@fb.com
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Currently, the codegen function might fail and return an error. But its
callers continue without checking its return value. Since codegen can
fail only in the unlikely case of the system running out of memory or
the static template being malformed, just exit(-1) directly from codegen
and make it void-returning.
Suggested-by: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200611103341.21532-1-tklauser@distanz.ch
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Free the memory allocated for the template on error paths in function
codegen.
Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200610130804.21423-1-tklauser@distanz.ch
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