linux.git/tools/lib/bpf/linker.c, branch for-next

libbpf: Stringify errno in log messages in the remaining code

2024-11-12T04:29:45+00:00

Convert numeric error codes into the string representations in log
messages in the rest of libbpf source files.

Signed-off-by: Mykyta Yatsenko 
Signed-off-by: Andrii Nakryiko 
Link: https://lore.kernel.org/bpf/20241111212919.368971-5-mykyta.yatsenko5@gmail.com

libbpf: Do not resolve size on duplicate FUNCs

2024-10-08T03:28:53+00:00

FUNCs do not have sizes, thus currently btf__resolve_size will fail
with -EINVAL. Add conditions so that we only update size when the BTF
object is not function or function prototype.

Signed-off-by: Eric Long 
Signed-off-by: Andrii Nakryiko 
Link: https://lore.kernel.org/bpf/20241002-libbpf-dup-extern-funcs-v4-1-560eb460ff90@hack3r.moe

libbpf: Support linking bpf objects of either endianness

2024-10-04T00:47:36+00:00

Allow static linking object files of either endianness, checking that input
files have consistent byte-order, and setting output endianness from input.

Linking requires in-memory processing of programs, relocations, sections,
etc. in native endianness, and output conversion to target byte-order. This
is enabled by built-in ELF translation and recent BTF/BTF.ext endianness
functions. Further add local functions for swapping byte-order of sections
containing BPF insns.

Signed-off-by: Tony Ambardar 
Signed-off-by: Andrii Nakryiko 
Link: https://lore.kernel.org/bpf/b47ca686d02664843fc99b96262fe3259650bc43.1726475448.git.tony.ambardar@gmail.com
Signed-off-by: Alexei Starovoitov

libbpf: Fix output .symtab byte-order during linking

2024-10-04T00:47:36+00:00

Object linking output data uses the default ELF_T_BYTE type for '.symtab'
section data, which disables any libelf-based translation. Explicitly set
the ELF_T_SYM type for output to restore libelf's byte-order conversion,
noting that input '.symtab' data is already correctly translated.

Fixes: faf6ed321cf6 ("libbpf: Add BPF static linker APIs")
Signed-off-by: Tony Ambardar 
Signed-off-by: Andrii Nakryiko 
Link: https://lore.kernel.org/bpf/87868bfeccf3f51aec61260073f8778e9077050a.1726475448.git.tony.ambardar@gmail.com
Signed-off-by: Alexei Starovoitov

libbpf: fix some typos in libbpf

2024-09-05T20:07:47+00:00

Hi, fix some spelling errors in libbpf, the details are as follows:

-in the code comments:
	termintaing->terminating
	architecutre->architecture
	requring->requiring
	recored->recoded
	sanitise->sanities
	allowd->allowed
	abover->above
	see bpf_udst_arg()->see bpf_usdt_arg()

Signed-off-by: Lin Yikai 
Link: https://lore.kernel.org/r/20240905110354.3274546-3-yikai.lin@vivo.com
Signed-off-by: Alexei Starovoitov

libbpf: Checking the btf_type kind when fixing variable offsets

2024-06-21T18:00:17+00:00

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

2024-06-05T14:54:32+00:00

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

2024-02-01T21:16:12+00:00

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

2023-12-21T09:05:15+00:00

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

2023-12-09T01:11:18+00:00

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