Release bpftool v7.6 · libbpf/bpftool

New features

Add new commands bpftool tracelog <stdout|stderr> PROG to print the BPF streams content of a given BPF program. (faad8ad)
Allow users to specify a custom path for BTF information when loading programs with bpftool. (6977b71)
Add a root_id argument when dumping a BTF object, in order to have bpftool print a minimized dump (type and dependencies) of a specific type from the BTF object. (2c5b7fd)
Add probe for ISA v4 instruction set extensions. New BPF instructions include: BPF_{SDIV,SMOD} (signed div and mod), BPF_{LD,LDX,ST,STX,MOV} (sign-extended load/store/move), 32-bit BPF_JA (unconditional jump), target-independent BPF_ALU64 BSWAP (byte-swapping 16/32/64). Availability is now probed as part of bpftool feature probe. (a5c0580)
Display additional information about BPF links, such as ref_ctr_offset for uprobe links, cookies for raw_tp probes and tracing probes. (1375884, c4c2dd0, 2406596)
Support "load-acquire" and "store-release" atomic instructions in the disassembler for translated programs. (452f644)
Make bpftool request fewer permissions, via libbpf's options, when possible for map operations: use read-only access for operations that don't require write access (for example, map creation requires write access, map dump can work with read-only access). (224edf4)

Fix an error for callq addresses printed when dumping translated programs, which was due to a wrong program counter (PC) value when calling the disassembler. (e4fbb51)
Fix a potential NULL pointer dereferencing error when dumping programs when we fail to retrieve kernel symbols correctly. (4608b98)
Fix a segfault when generating the control flow graph (CFG) with a building block containing a BPF_CALL as last instruction. (731868d)
Fix a regression for bpftool cgroup tree, potentially causing bpftool to complain about an invalid argument when it should just skip unsupported attach types that are not supported on older kernels. (ede6487)
Fix bpftool cgroup show to make it show only cgroup BPF programs. Some conflicting C union values would make it dump netkit programs if the netkit device has ifindex 3. (35cab59)
When dumping BTF objects, validate root_type_ids early. This prevents bpftool from doing a partial dump before doing an unclean exit. (a3150e1)
Set the error code when failing to open the object file for loading programs, rather than returning 0 as if the command had succeeded. (30e4f38)
Fix a memory leak in the JSON writer, when printing bpftool's version. (f0358a7)
Fix a memory leak due to a bad realloc() usage, when listing networking programs. (5380d18)
Add missing format argument to command description for bpftool btf dump in man page. (9e14c3b)

BPF map names can contain a maximum of 15 characters. When a user creates a map with bpftool and passes a name that is too long, the name gets truncated. This truncation was silent; now, bpftool prints a warning in this case. (60b1305)
Avoid setting the _GNU_SOURCE macro multiple times in the Makefile when compiling with clang. (aa631ec)
Fix Makefile's linker flags to pass the zstd library when libelf requires it as a dependency. This fixed the linker flags for libelf in bpftool in the kernel repository. However, the corresponding probe in the mirror repository was only added in commit f964613, which is not included in v7.6.0. (67f1758)
Compile bpftool with -Wformat-signedness to detect format errors. Several errors of this kind have been fixed, too. (4c56992, 02d3ecd, 4c363d6)

Static builds on Ubuntu 24.04 may fail because of a missing linker flag to add the zstd library. Note: this is now fixed in the main branch. (#152)
Static builds on Ubuntu 24.04 relying on the libbfd-based disassembler may fail as well, because of missing linker flags to add the zstd and sframe libraries. Workarounds include using the LLVM-based disassembler instead, using no disassembler, using libbfd < 2.40, or manually overwriting all LIBS flags when building bpftool (it's ugly but it works). (#73)

Full Changelog: v7.5.0...v7.6.0