kernel.git/tools/lib/bpf/libbpf_internal.h, branch linux-5.10.y

libbpf: Make btf_dump work with modifiable BTF

2020-09-30T19:30:22Z

Ensure that btf_dump can accommodate new BTF types being appended to BTF instance after struct btf_dump was created. This came up during attemp to use btf_dump for raw type dumping in selftests, but given changes are not excessive, it's good to not have any gotchas in API usage, so I decided to support such use case in general. Signed-off-by: Andrii Nakryiko Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20200929232843.1249318-2-andriin@fb.com

libbpf: Generalize common logic for managing dynamically-sized arrays

2020-09-29T00:27:31Z

Managing dynamically-sized array is a common, but not trivial functionality, which significant amount of logic and code to implement properly. So instead of re-implementing it all the time, extract it into a helper function ans reuse. Signed-off-by: Andrii Nakryiko Signed-off-by: Alexei Starovoitov Acked-by: John Fastabend Link: https://lore.kernel.org/bpf/20200926011357.2366158-4-andriin@fb.com

libbpf: Support test run of raw tracepoint programs

2020-09-28T19:52:36Z

Add bpf_prog_test_run_opts() with support of new fields in bpf_attr.test, namely, flags and cpu. Also extend _opts operations to support outputs via opts. Signed-off-by: Song Liu Signed-off-by: Daniel Borkmann Acked-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20200925205432.1777-3-songliubraving@fb.com

libbpf: Fix libbpf build on compilers missing __builtin_mul_overflow

2020-08-20T14:45:09Z

GCC compilers older than version 5 don't support __builtin_mul_overflow yet. Given GCC 4.9 is the minimal supported compiler for building kernel and the fact that libbpf is a dependency of resolve_btfids, which is dependency of CONFIG_DEBUG_INFO_BTF=y, this needs to be handled. This patch fixes the issue by falling back to slower detection of integer overflow in such cases. Fixes: 029258d7b228 ("libbpf: Remove any use of reallocarray() in libbpf") Signed-off-by: Andrii Nakryiko Signed-off-by: Daniel Borkmann Acked-by: Yonghong Song Link: https://lore.kernel.org/bpf/20200820061411.1755905-2-andriin@fb.com

libbpf: Implement enum value-based CO-RE relocations

2020-08-19T21:19:39Z

Implement two relocations of a new enumerator value-based CO-RE relocation kind: ENUMVAL_EXISTS and ENUMVAL_VALUE. First, ENUMVAL_EXISTS, allows to detect the presence of a named enumerator value in the target (kernel) BTF. This is useful to do BPF helper/map/program type support detection from BPF program side. bpf_core_enum_value_exists() macro helper is provided to simplify built-in usage. Second, ENUMVAL_VALUE, allows to capture enumerator integer value and relocate it according to the target BTF, if it changes. This is useful to have a guarantee against intentional or accidental re-ordering/re-numbering of some of the internal (non-UAPI) enumerations, where kernel developers don't care about UAPI backwards compatiblity concerns. bpf_core_enum_value() allows to capture this succinctly and use correct enum values in code. LLVM uses ldimm64 instruction to capture enumerator value-based relocations, so add support for ldimm64 instruction patching as well. Signed-off-by: Andrii Nakryiko Signed-off-by: Alexei Starovoitov Acked-by: Yonghong Song Link: https://lore.kernel.org/bpf/20200819194519.3375898-5-andriin@fb.com

libbpf: Implement type-based CO-RE relocations support

2020-08-19T21:19:39Z

Implement support for TYPE_EXISTS/TYPE_SIZE/TYPE_ID_LOCAL/TYPE_ID_REMOTE relocations. These are examples of type-based relocations, as opposed to field-based relocations supported already. The difference is that they are calculating relocation values based on the type itself, not a field within a struct/union. Type-based relos have slightly different semantics when matching local types to kernel target types, see comments in bpf_core_types_are_compat() for details. Their behavior on failure to find target type in kernel BTF also differs. Instead of "poisoning" relocatable instruction and failing load subsequently in kernel, they return 0 (which is rarely a valid return result, so user BPF code can use that to detect success/failure of the relocation and deal with it without extra "guarding" relocations). Also, it's always possible to check existence of the type in target kernel with TYPE_EXISTS relocation, similarly to a field-based FIELD_EXISTS. TYPE_ID_LOCAL relocation is a bit special in that it always succeeds (barring any libbpf/Clang bugs) and resolved to BTF ID using **local** BTF info of BPF program itself. Tests in subsequent patches demonstrate the usage and semantics of new relocations. Signed-off-by: Andrii Nakryiko Signed-off-by: Alexei Starovoitov Acked-by: Yonghong Song Link: https://lore.kernel.org/bpf/20200819194519.3375898-2-andriin@fb.com

libbpf: Centralize poisoning and poison reallocarray()

2020-08-19T01:38:25Z

Most of libbpf source files already include libbpf_internal.h, so it's a good place to centralize identifier poisoning. So move kernel integer type poisoning there. And also add reallocarray to a poison list to prevent accidental use of it. libbpf_reallocarray() should be used universally instead. Signed-off-by: Andrii Nakryiko Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20200819013607.3607269-4-andriin@fb.com

tools/bpftool: Remove libbpf_internal.h usage in bpftool

2020-08-19T01:38:25Z

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 Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20200819013607.3607269-3-andriin@fb.com

libbpf: Remove any use of reallocarray() in libbpf

2020-08-19T01:38:25Z

Re-implement glibc's reallocarray() for libbpf internal-only use. reallocarray(), unfortunately, is not available in all versions of glibc, so requires extra feature detection and using reallocarray() stub from and COMPAT_NEED_REALLOCARRAY. All this complicates build of libbpf unnecessarily and is just a maintenance burden. Instead, it's trivial to implement libbpf-specific internal version and use it throughout libbpf. Which is what this patch does, along with converting some realloc() uses that should really have been reallocarray() in the first place. Signed-off-by: Andrii Nakryiko Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20200819013607.3607269-2-andriin@fb.com

libbpf: Clean up and improve CO-RE reloc logging

2020-08-19T01:12:45Z

Add logging of local/target type kind (struct/union/typedef/etc). Preserve unresolved root type ID (for cases of typedef). Improve the format of CO-RE reloc spec output format to contain only relevant and succinct info. Signed-off-by: Andrii Nakryiko Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20200818223921.2911963-3-andriin@fb.com