linux-toradex.git/tools/testing/selftests/bpf/Makefile, branch master

selftests/bpf: Fix pkg-config call on static builds

2026-03-10T19:04:00+00:00

For commit b0dcdcb9ae75 ("resolve_btfids: Fix linker flags detection"),
I suggested setting HOSTPKG_CONFIG to $PKG_CONFIG when compiling
resolve_btfids, but I forgot the quotes around that variable.

As a result, when running vmtest.sh with static linking, it fails as
follows:

    $ LDLIBS=-static PKG_CONFIG='pkg-config --static' ./vmtest.sh
    [...]
    make: unrecognized option '--static'
    Usage: make [options] [target] ...
    [...]

This worked when I tested it because HOSTPKG_CONFIG didn't have a
default value in the resolve_btfids Makefile, but once it does, the
quotes aren't preserved and it fails on the next make call.

Fixes: b0dcdcb9ae75 ("resolve_btfids: Fix linker flags detection")
Signed-off-by: Paul Chaignon 
Acked-by: Mykyta Yatsenko 
Acked-by: Ihor Solodrai 
Link: https://lore.kernel.org/r/abADBwn_ykblpABE@mail.gmail.com
Signed-off-by: Alexei Starovoitov

resolve_btfids: Fix linker flags detection

2026-03-07T16:51:51+00:00

The "|| echo -lzstd" default makes zstd an unconditional link
dependency of resolve_btfids. On systems where libzstd-dev is not
installed and pkg-config fails, the linker fails:

  ld: cannot find -lzstd: No such file or directory

libzstd is a transitive dependency of libelf, so the -lzstd flag is
strictly necessary only for static builds [1].

Remove ZSTD_LIBS variable, and instead set LIBELF_LIBS depending on
whether the build is static or not. Use $(HOSTPKG_CONFIG) as primary
source of the flags list.

Also add a default value for HOSTPKG_CONFIG in case it's not built via
the toplevel Makefile. Pass it from selftests/bpf too.

[1] https://lore.kernel.org/bpf/4ff82800-2daa-4b9f-95a9-6f512859ee70@linux.dev/

Reported-by: BPF CI Bot (Claude Opus 4.6) 
Reported-by: Vitaly Chikunov 
Closes: https://lore.kernel.org/bpf/aaWqMcK-2AQw5dx8@altlinux.org/
Fixes: 4021848a903e ("selftests/bpf: Pass through build flags to bpftool and resolve_btfids")
Signed-off-by: Ihor Solodrai 
Reviewed-by: Paul Chaignon 
Link: https://lore.kernel.org/r/20260305014730.3123382-1-ihor.solodrai@linux.dev
Signed-off-by: Alexei Starovoitov

selftests/bpf: Pass through build flags to bpftool and resolve_btfids

2026-02-24T16:19:49+00:00

EXTRA_* and SAN_* build flags were not correctly propagated to bpftool
and resolve_btids when building selftests/bpf. This led to various
build errors on attempt to build with SAN_CFLAGS="-fsanitize=address",
for example.

Fix the makefiles to address this:
  - Pass SAN_CFLAGS/SAN_LDFLAGS to bpftool and resolve_btfids build
  - Propagate EXTRA_LDFLAGS to resolve_btfids link command
  - Use pkg-config to detect zlib and zstd for resolve_btfids, similar
    libelf handling

Also check for ASAN flag in selftests/bpf/Makefile for convenience.

Signed-off-by: Ihor Solodrai 
Link: https://lore.kernel.org/r/20260223190736.649171-7-ihor.solodrai@linux.dev
Signed-off-by: Alexei Starovoitov

selftests/bpf: Remove hexdump dependency

2026-02-18T23:11:20+00:00

The verification signature header generation requires converting a
binary certificate to a C array. Previously this only worked with xxd,
and a switch to hexdump has been done in commit b640d556a2b3
("selftests/bpf: Remove xxd util dependency").

hexdump is a more common utility program, yet it might not be installed
by default. When it is not installed, BPF selftests build without
errors, but tests_progs is unusable: it exits with the 255 code and
without any error messages. When manually reproducing the issue, it is
not too hard to find out that the generated verification_cert.h file is
incorrect, but that's time consuming. When digging the BPF selftests
build logs, this line can be seen amongst thousands others, but ignored:

  /bin/sh: 2: hexdump: not found

Here, od is used instead of hexdump. od is coming from the coreutils
package, and this new od command produces the same output when using od
from GNU coreutils, uutils, and even busybox. This is more portable, and
it produces a similar results to what was done before with hexdump:
there is an extra comma at the end instead of trailing whitespaces,
but the C code is not impacted.

Fixes: b640d556a2b3 ("selftests/bpf: Remove xxd util dependency")
Signed-off-by: Matthieu Baerts (NGI0) 
Tested-by: Alan Maguire 
Link: https://lore.kernel.org/r/20260218-bpf-sft-hexdump-od-v2-1-2f9b3ee5ab86@kernel.org
Signed-off-by: Alexei Starovoitov

selftests/bpf: Remove xxd util dependency

2026-01-28T21:23:51+00:00

The verification signature header generation requires converting a
binary certificate to a C array. Previously this only worked with
xxd (part of vim-common package).
As xxd may not be available on some systems building selftests, it makes
sense to substitute it with more common utils: hexdump, wc, sed to
generate equivalent C array output.

Tested by generating header with both xxd and hexdump and comparing
them.

Signed-off-by: Mykyta Yatsenko 
Signed-off-by: Andrii Nakryiko 
Tested-by: Alan Maguire 
Link: https://lore.kernel.org/bpf/20260128190552.242335-1-mykyta.yatsenko5@gmail.com

selftests/bpf: convert test_bpftool_map_access.sh into test_progs framework

2026-01-27T02:47:31+00:00

The test_bpftool_map.sh script tests that maps read/write accesses
are being properly allowed/refused by the kernel depending on a specific
fmod_ret program being attached on security_bpf_map function.

Rewrite this test to integrate it in the test_progs. The
new test spawns a few subtests:

  #36/1    bpftool_maps_access/unprotected_unpinned:OK
  #36/2    bpftool_maps_access/unprotected_pinned:OK
  #36/3    bpftool_maps_access/protected_unpinned:OK
  #36/4    bpftool_maps_access/protected_pinned:OK
  #36/5    bpftool_maps_access/nested_maps:OK
  #36/6    bpftool_maps_access/btf_list:OK
  #36      bpftool_maps_access:OK
  Summary: 1/6 PASSED, 0 SKIPPED, 0 FAILED

Signed-off-by: Alexis Lothoré (eBPF Foundation) 
Acked-by: Quentin Monnet 
Link: https://lore.kernel.org/r/20260123-bpftool-tests-v4-3-a6653a7f28e7@bootlin.com
Signed-off-by: Alexei Starovoitov

selftests/bpf: convert test_bpftool_metadata.sh into test_progs framework

2026-01-27T02:47:31+00:00

The test_bpftool_metadata.sh script validates that bpftool properly
returns in its ouptput any metadata generated by bpf programs through
some .rodata sections.

Port this test to the test_progs framework so that it can be executed
automatically in CI. The new test, similarly to the former script,
checks that valid data appears both for textual output and json output,
as well as for both data not used at all and used data. For the json
check part, the expected json string is hardcoded to avoid bringing a
new external dependency (eg: a json deserializer) for test_progs.
As the test is now converted into test_progs, remove the former script.

The newly converted test brings two new subtests:

  #37/1    bpftool_metadata/metadata_unused:OK
  #37/2    bpftool_metadata/metadata_used:OK
  #37      bpftool_metadata:OK
  Summary: 1/2 PASSED, 0 SKIPPED, 0 FAILED

Signed-off-by: Alexis Lothoré (eBPF Foundation) 
Link: https://lore.kernel.org/r/20260123-bpftool-tests-v4-2-a6653a7f28e7@bootlin.com
Signed-off-by: Alexei Starovoitov

selftests/bpf: Add a few helpers for bpftool testing

2026-01-27T02:47:21+00:00

In order to integrate some bpftool tests into test_progs, define a few
specific helpers that allow to execute bpftool commands, while possibly
retrieving the command output. Those helpers most notably set the
path to the bpftool binary under test. This version checks different
possible paths relative to the directories where the different
test_progs runners are executed, as we want to make sure not to
accidentally use a bootstrap version of the binary.

Signed-off-by: Alexis Lothoré (eBPF Foundation) 
Link: https://lore.kernel.org/r/20260123-bpftool-tests-v4-1-a6653a7f28e7@bootlin.com
Signed-off-by: Alexei Starovoitov

resolve_btfids: Implement --patch_btfids

2025-12-31T17:04:09+00:00

Recent changes in BTF generation [1] rely on ${OBJCOPY} command to
update .BTF_ids section data in target ELF files.

This exposed a bug in llvm-objcopy --update-section code path, that
may lead to corruption of a target ELF file. Specifically, because of
the bug st_shndx of some symbols may be (incorrectly) set to 0xffff
(SHN_XINDEX) [2][3].

While there is a pending fix for LLVM, it'll take some time before it
lands (likely in 22.x). And the kernel build must keep working with
older LLVM toolchains in the foreseeable future.

Using GNU objcopy for .BTF_ids update would work, but it would require
changes to LLVM-based build process, likely breaking existing build
environments as discussed in [2].

To work around llvm-objcopy bug, implement --patch_btfids code path in
resolve_btfids as a drop-in replacement for:

    ${OBJCOPY} --update-section .BTF_ids=${btf_ids} ${elf}

Which works specifically for .BTF_ids section:

    ${RESOLVE_BTFIDS} --patch_btfids ${btf_ids} ${elf}

This feature in resolve_btfids can be removed at some point in the
future, when llvm-objcopy with a relevant bugfix becomes common.

[1] https://lore.kernel.org/bpf/20251219181321.1283664-1-ihor.solodrai@linux.dev/
[2] https://lore.kernel.org/bpf/20251224005752.201911-1-ihor.solodrai@linux.dev/
[3] https://github.com/llvm/llvm-project/issues/168060#issuecomment-3533552952

Signed-off-by: Ihor Solodrai 
Link: https://lore.kernel.org/r/20251231012558.1699758-1-ihor.solodrai@linux.dev
Signed-off-by: Alexei Starovoitov

resolve_btfids: Change in-place update with raw binary output

2025-12-19T18:55:40+00:00

Currently resolve_btfids updates .BTF_ids section of an ELF file
in-place, based on the contents of provided BTF, usually within the
same input file, and optionally a BTF base.

Change resolve_btfids behavior to enable BTF transformations as part
of its main operation. To achieve this, in-place ELF write in
resolve_btfids is replaced with generation of the following binaries:
  * ${1}.BTF with .BTF section data
  * ${1}.BTF_ids with .BTF_ids section data if it existed in ${1}
  * ${1}.BTF.base with .BTF.base section data for out-of-tree modules

The execution of resolve_btfids and consumption of its output is
orchestrated by scripts/gen-btf.sh introduced in this patch.

The motivation for emitting binary data is that it allows simplifying
resolve_btfids implementation by delegating ELF update to the $OBJCOPY
tool [1], which is already widely used across the codebase.

There are two distinct paths for BTF generation and resolve_btfids
application in the kernel build: for vmlinux and for kernel modules.

For the vmlinux binary a .BTF section is added in a roundabout way to
ensure correct linking. The patch doesn't change this approach, only
the implementation is a little different.

Before this patch it worked as follows:

  * pahole consumed .tmp_vmlinux1 [2] and added .BTF section with
    llvm-objcopy [3] to it
  * then everything except the .BTF section was stripped from .tmp_vmlinux1
    into a .tmp_vmlinux1.bpf.o object [2], later linked into vmlinux
  * resolve_btfids was executed later on vmlinux.unstripped [4],
    updating it in-place

After this patch gen-btf.sh implements the following:

  * pahole consumes .tmp_vmlinux1 and produces a *detached* file with
    raw BTF data
  * resolve_btfids consumes .tmp_vmlinux1 and detached BTF to produce
    (potentially modified) .BTF, and .BTF_ids sections data
  * a .tmp_vmlinux1.bpf.o object is then produced with objcopy copying
    BTF output of resolve_btfids
  * .BTF_ids data gets embedded into vmlinux.unstripped in
    link-vmlinux.sh by objcopy --update-section

For kernel modules, creating a special .bpf.o file is not necessary,
and so embedding of sections data produced by resolve_btfids is
straightforward with objcopy.

With this patch an ELF file becomes effectively read-only within
resolve_btfids, which allows deleting elf_update() call and satellite
code (like compressed_section_fix [5]).

Endianness handling of .BTF_ids data is also changed. Previously the
"flags" part of the section was bswapped in sets_patch() [6], and then
Elf_Type was modified before elf_update() to signal to libelf that
bswap may be necessary. With this patch we explicitly bswap entire
data buffer on load and on dump.

[1] https://lore.kernel.org/bpf/131b4190-9c49-4f79-a99d-c00fac97fa44@linux.dev/
[2] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/scripts/link-vmlinux.sh?h=v6.18#n110
[3] https://git.kernel.org/pub/scm/devel/pahole/pahole.git/tree/btf_encoder.c?h=v1.31#n1803
[4] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/scripts/link-vmlinux.sh?h=v6.18#n284
[5] https://lore.kernel.org/bpf/20200819092342.259004-1-jolsa@kernel.org/
[6] https://lore.kernel.org/bpf/cover.1707223196.git.vmalik@redhat.com/

Signed-off-by: Ihor Solodrai 
Signed-off-by: Andrii Nakryiko 
Tested-by: Alan Maguire 
Acked-by: Eduard Zingerman 
Link: https://lore.kernel.org/bpf/20251219181825.1289460-3-ihor.solodrai@linux.dev