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

libbpf: Skip forward declaration when counting duplicated type names

2022-03-01T12:40:57+00:00

Currently if a declaration appears in the BTF before the definition, the
definition is dumped as a conflicting name, e.g.:

    $ bpftool btf dump file vmlinux format raw | grep "'unix_sock'"
    [81287] FWD 'unix_sock' fwd_kind=struct
    [89336] STRUCT 'unix_sock' size=1024 vlen=14

    $ bpftool btf dump file vmlinux format c | grep "struct unix_sock"
    struct unix_sock;
    struct unix_sock___2 {	<--- conflict, the "___2" is unexpected
		    struct unix_sock___2 *unix_sk;

This causes a compilation error if the dump output is used as a header file.

Fix it by skipping declaration when counting duplicated type names.

Fixes: 351131b51c7a ("libbpf: add btf_dump API for BTF-to-C conversion")
Signed-off-by: Xu Kuohai 
Signed-off-by: Daniel Borkmann 
Acked-by: Song Liu 
Link: https://lore.kernel.org/bpf/20220301053250.1464204-2-xukuohai@huawei.com

libbpf: Fix compilation warning due to mismatched printf format

2022-02-09T13:33:32+00:00

On ppc64le architecture __s64 is long int and requires %ld. Cast to
ssize_t and use %zd to avoid architecture-specific specifiers.

Fixes: 4172843ed4a3 ("libbpf: Fix signedness bug in btf_dump_array_data()")
Signed-off-by: Andrii Nakryiko 
Signed-off-by: Daniel Borkmann 
Link: https://lore.kernel.org/bpf/20220209063909.1268319-1-andrii@kernel.org

libbpf: Fix signedness bug in btf_dump_array_data()

2022-02-08T21:34:44+00:00

The btf__resolve_size() function returns negative error codes so
"elem_size" must be signed for the error handling to work.

Fixes: 920d16af9b42 ("libbpf: BTF dumper support for typed data")
Signed-off-by: Dan Carpenter 
Signed-off-by: Daniel Borkmann 
Acked-by: Yonghong Song 
Link: https://lore.kernel.org/bpf/20220208071552.GB10495@kili

libbpf: Add sane strncpy alternative and use it internally

2021-12-14T14:47:56+00:00

strncpy() has a notoriously error-prone semantics which makes GCC
complain about it a lot (and quite often completely completely falsely
at that). Instead of pleasing GCC all the time (-Wno-stringop-truncation
is unfortunately only supported by GCC, so it's a bit too messy to just
enable it in Makefile), add libbpf-internal libbpf_strlcpy() helper
which follows what FreeBSD's strlcpy() does and what most people would
expect from strncpy(): copies up to N-1 first bytes from source string
into destination string and ensures zero-termination afterwards.

Replace all the relevant uses of strncpy/strncat/memcpy in libbpf with
libbpf_strlcpy().

This also fixes the issue reported by Emmanuel Deloget in xsk.c where
memcpy() could access source string beyond its end.

Fixes: 2f6324a3937f8 (libbpf: Support shared umems between queues and devices)
Reported-by: Emmanuel Deloget 
Signed-off-by: Andrii Nakryiko 
Signed-off-by: Daniel Borkmann 
Link: https://lore.kernel.org/bpf/20211211004043.2374068-1-andrii@kernel.org

libbpf: Silence uninitialized warning/error in btf_dump_dump_type_data

2021-11-29T17:36:44+00:00

When compiling libbpf with gcc 4.8.5, we see:

  CC       staticobjs/btf_dump.o
btf_dump.c: In function ‘btf_dump_dump_type_data.isra.24’:
btf_dump.c:2296:5: error: ‘err’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
  if (err < 0)
     ^
cc1: all warnings being treated as errors
make: *** [staticobjs/btf_dump.o] Error 1

While gcc 4.8.5 is too old to build the upstream kernel, it's possible it
could be used to build standalone libbpf which suffers from the same problem.
Silence the error by initializing 'err' to 0.  The warning/error seems to be
a false positive since err is set early in the function.  Regardless we
shouldn't prevent libbpf from building for this.

Fixes: 920d16af9b42 ("libbpf: BTF dumper support for typed data")
Signed-off-by: Alan Maguire 
Signed-off-by: Andrii Nakryiko 
Link: https://lore.kernel.org/bpf/1638180040-8037-1-git-send-email-alan.maguire@oracle.com

libbpf: Support BTF_KIND_TYPE_TAG

2021-11-12T01:41:11+00:00

Add libbpf support for BTF_KIND_TYPE_TAG.

Signed-off-by: Yonghong Song 
Signed-off-by: Alexei Starovoitov 
Acked-by: Andrii Nakryiko 
Link: https://lore.kernel.org/bpf/20211112012614.1505315-1-yhs@fb.com

libbpf: Ensure btf_dump__new() and btf_dump_opts are future-proof

2021-11-12T00:54:05+00:00

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 
Signed-off-by: Alexei Starovoitov 
Link: https://lore.kernel.org/bpf/20211111053624.190580-5-andrii@kernel.org

libbpf: Use __BYTE_ORDER__

2021-10-26T03:39:41+00:00

Use the compiler-defined __BYTE_ORDER__ instead of the libc-defined
__BYTE_ORDER for consistency.

Signed-off-by: Ilya Leoshkevich 
Signed-off-by: Andrii Nakryiko 
Link: https://lore.kernel.org/bpf/20211026010831.748682-3-iii@linux.ibm.com

libbpf: Add btf__type_cnt() and btf__raw_data() APIs

2021-10-22T23:09:14+00:00

Add btf__type_cnt() and btf__raw_data() APIs and deprecate
btf__get_nr_type() and btf__get_raw_data() since the old APIs
don't follow the libbpf naming convention for getters which
omit 'get' in the name (see [0]). btf__raw_data() is just an
alias to the existing btf__get_raw_data(). btf__type_cnt()
now returns the number of all types of the BTF object
including 'void'.

  [0] Closes: https://github.com/libbpf/libbpf/issues/279

Signed-off-by: Hengqi Chen 
Signed-off-by: Andrii Nakryiko 
Link: https://lore.kernel.org/bpf/20211022130623.1548429-2-hengqi.chen@gmail.com

libbpf: Fix the use of aligned attribute

2021-10-22T21:24:36+00:00

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 
Signed-off-by: Alexei Starovoitov 
Link: https://lore.kernel.org/bpf/20211022192502.2975553-1-andrii@kernel.org