wireguard-linux/tools/lib/bpf/linker.c, branch jd/bump-compilers

libbpf: Checking the btf_type kind when fixing variable offsets

2024-06-21T18:00:17Z

I encountered an issue when building the test_progs from the repository [1]: $ pwd /work/Qemu/x86_64/linux-6.10-rc2/tools/testing/selftests/bpf/ $ make test_progs V=1 [...] ./tools/sbin/bpftool gen object ./ip_check_defrag.bpf.linked2.o ./ip_check_defrag.bpf.linked1.o libbpf: failed to find symbol for variable 'bpf_dynptr_slice' in section '.ksyms' Error: failed to link './ip_check_defrag.bpf.linked1.o': No such file or directory (2) [...] Upon investigation, I discovered that the btf_types referenced in the '.ksyms' section had a kind of BTF_KIND_FUNC instead of BTF_KIND_VAR: $ bpftool btf dump file ./ip_check_defrag.bpf.linked1.o [...] [2] DATASEC '.ksyms' size=0 vlen=2 type_id=16 offset=0 size=0 (FUNC 'bpf_dynptr_from_skb') type_id=17 offset=0 size=0 (FUNC 'bpf_dynptr_slice') [...] [16] FUNC 'bpf_dynptr_from_skb' type_id=82 linkage=extern [17] FUNC 'bpf_dynptr_slice' type_id=85 linkage=extern [...] For a detailed analysis, please refer to [2]. We can add a kind checking to fix the issue. [1] https://github.com/eddyz87/bpf/tree/binsort-btf-dedup [2] https://lore.kernel.org/all/0c0ef20c-c05e-4db9-bad7-2cbc0d6dfae7@oracle.com/ Fixes: 8fd27bf69b86 ("libbpf: Add BPF static linker BTF and BTF.ext support") Signed-off-by: Donglin Peng Signed-off-by: Daniel Borkmann Reviewed-by: Alan Maguire Acked-by: Eduard Zingerman Link: https://lore.kernel.org/bpf/20240619122355.426405-1-dolinux.peng@gmail.com

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

2024-06-05T14:54:32Z

Switch all BPF linker code dealing with iterating BTF type ID and string offset fields to new btf_field_iter facilities. Signed-off-by: Andrii Nakryiko Signed-off-by: Daniel Borkmann Tested-by: Alan Maguire Acked-by: Eduard Zingerman Acked-by: Jiri Olsa Link: https://lore.kernel.org/bpf/20240605001629.4061937-3-andrii@kernel.org

libbpf: Add missed btf_ext__raw_data() API

2024-02-01T21:16:12Z

Another API that was declared in libbpf.map but actual implementation was missing. btf_ext__get_raw_data() was intended as a discouraged alias to consistently-named btf_ext__raw_data(), so make this an actuality. Fixes: 20eccf29e297 ("libbpf: hide and discourage inconsistently named getters") Signed-off-by: Andrii Nakryiko Signed-off-by: Daniel Borkmann Acked-by: Eduard Zingerman Link: https://lore.kernel.org/bpf/20240201172027.604869-5-andrii@kernel.org

libbpf: Skip DWARF sections in linker sanity check

2023-12-21T09:05:15Z

clang can generate (with -g -Wa,--compress-debug-sections) 4-byte aligned DWARF sections that declare themselves to be 8-byte aligned in the section header. Since DWARF sections are dropped during linking anyway, just skip running the sanity checks on them. Reported-by: Sergei Trofimovich Suggested-by: Andrii Nakryiko Signed-off-by: Alyssa Ross Signed-off-by: Andrii Nakryiko Signed-off-by: Daniel Borkmann Acked-by: Daniel Borkmann Closes: https://lore.kernel.org/bpf/ZXcFRJVKbKxtEL5t@nz.home/ Link: https://lore.kernel.org/bpf/20231219110324.8989-1-hi@alyssa.is

libbpf: Add pr_warn() for EINVAL cases in linker_sanity_check_elf

2023-12-09T01:11:18Z

Before the change on `i686-linux` `systemd` build failed as: $ bpftool gen object src/core/bpf/socket_bind/socket-bind.bpf.o src/core/bpf/socket_bind/socket-bind.bpf.unstripped.o Error: failed to link 'src/core/bpf/socket_bind/socket-bind.bpf.unstripped.o': Invalid argument (22) After the change it fails as: $ bpftool gen object src/core/bpf/socket_bind/socket-bind.bpf.o src/core/bpf/socket_bind/socket-bind.bpf.unstripped.o libbpf: ELF section #9 has inconsistent alignment addr=8 != d=4 in src/core/bpf/socket_bind/socket-bind.bpf.unstripped.o Error: failed to link 'src/core/bpf/socket_bind/socket-bind.bpf.unstripped.o': Invalid argument (22) Now it's slightly easier to figure out what is wrong with an ELF file. Signed-off-by: Sergei Trofimovich Signed-off-by: Andrii Nakryiko Acked-by: Eduard Zingerman Link: https://lore.kernel.org/bpf/20231208215100.435876-1-slyich@gmail.com

libbpf: Fix double-free when linker processes empty sections

2023-03-28T03:02:15Z

Double-free error in bpf_linker__free() was reported by James Hilliard. The error is caused by miss-use of realloc() in extend_sec(). The error occurs when two files with empty sections of the same name are linked: - when first file is processed: - extend_sec() calls realloc(dst->raw_data, dst_align_sz) with dst->raw_data == NULL and dst_align_sz == 0; - dst->raw_data is set to a special pointer to a memory block of size zero; - when second file is processed: - extend_sec() calls realloc(dst->raw_data, dst_align_sz) with dst->raw_data == and dst_align_sz == 0; - realloc() "frees" dst->raw_data special pointer and returns NULL; - extend_sec() exits with -ENOMEM, and the old dst->raw_data value is preserved (it is now invalid); - eventually, bpf_linker__free() attempts to free dst->raw_data again. This patch fixes the bug by avoiding -ENOMEM exit for dst_align_sz == 0. The fix was suggested by Andrii Nakryiko . Reported-by: James Hilliard Signed-off-by: Eduard Zingerman Signed-off-by: Andrii Nakryiko Tested-by: James Hilliard Link: https://lore.kernel.org/bpf/CADvTj4o7ZWUikKwNTwFq0O_AaX+46t_+Ca9gvWMYdWdRtTGeHQ@mail.gmail.com/ Link: https://lore.kernel.org/bpf/20230328004738.381898-3-eddyz87@gmail.com

libbpf: Cleanup linker_append_elf_relos

2023-03-01T19:13:11Z

Clang Static Analyser (scan-build) reports some unused symbols and dead assignments in the linker_append_elf_relos function. Clean these up. Signed-off-by: Viktor Malik Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/c5c8fe9f411b69afada8399d23bb048ef2a70535.1677658777.git.vmalik@redhat.com

libbpf: Add enum64 support for bpf linking

2022-06-07T17:20:43Z

Add BTF_KIND_ENUM64 support for bpf linking, which is very similar to BTF_KIND_ENUM. Acked-by: Andrii Nakryiko Signed-off-by: Yonghong Song Link: https://lore.kernel.org/r/20220607062642.3721494-1-yhs@fb.com Signed-off-by: Alexei Starovoitov

libbpf: Fix is_pow_of_2

2022-06-03T21:53:33Z

Move the correct definition from linker.c into libbpf_internal.h. Fixes: 0087a681fa8c ("libbpf: Automatically fix up BPF_MAP_TYPE_RINGBUF size, if necessary") Reported-by: Yuze Chi Signed-off-by: Yuze Chi Signed-off-by: Ian Rogers Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20220603055156.2830463-1-irogers@google.com

libbpf: Fix using invalidated memory in bpf_linker

2021-11-25T23:15:03Z

add_dst_sec() can invalidate bpf_linker's section index making dst_symtab pointer pointing into unallocated memory. Reinitialize dst_symtab pointer on each iteration to make sure it's always valid. Fixes: faf6ed321cf6 ("libbpf: Add BPF static linker APIs") Signed-off-by: Andrii Nakryiko Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/20211124002325.1737739-7-andrii@kernel.org