On Mon, Sep 20, 2021 at 7:15 AM Kumar Kartikeya Dwivedi <memxor@xxxxxxxxx> wrote: > > This set enables kernel module function calls, and also modifies verifier logic > to permit invalid kernel function calls as long as they are pruned as part of > dead code elimination. This is done to provide better runtime portability for > BPF objects, which can conditionally disable parts of code that are pruned later > by the verifier (e.g. const volatile vars, kconfig options). libbpf > modifications are made along with kernel changes to support module function > calls. The set includes gen_loader support for emitting kfunc relocations. > > It also converts TCP congestion control objects to use the module kfunc support > instead of relying on IS_BUILTIN ifdef. > > Changelog: > ---------- > v3 -> v4 Please use vmtest.sh locally to test everything. That should help to avoid breaking our CI ([0]): test_ksyms_module_libbpf:PASS:test_ksyms_module_libbpf__open 0 nsec test_ksyms_module_libbpf:PASS:bpf_program__set_autoload false load_fail1 0 nsec test_ksyms_module_libbpf:PASS:bpf_program__set_autoload false load_fail2 0 nsec libbpf: load bpf program failed: Invalid argument libbpf: -- BEGIN DUMP LOG --- libbpf: kernel btf_id 81786 is not a function processed 0 insns (limit 1000000) max_states_per_insn 0 total_states 0 peak_states 0 mark_read 0 libbpf: -- END LOG -- libbpf: failed to load program 'handler' libbpf: failed to load object 'test_ksyms_module_libbpf' libbpf: failed to load BPF skeleton 'test_ksyms_module_libbpf': -4007 test_ksyms_module_libbpf:FAIL:test_ksyms_module_libbpf__load unexpected error: -4007 (errno 4007) #66 ksyms_module_libbpf:FAIL test_module_attach:PASS:skel_open 0 nsec test_module_attach:PASS:set_attach_target 0 nsec libbpf: load bpf program failed: Invalid argument libbpf: -- BEGIN DUMP LOG --- libbpf: attach_btf_id 81768 is invalid processed 0 insns (limit 1000000) max_states_per_insn 0 total_states 0 peak_states 0 mark_read 0 libbpf: -- END LOG -- libbpf: failed to load program 'handle_tp_btf' libbpf: failed to load object 'test_module_attach' libbpf: failed to load BPF skeleton 'test_module_attach': -4007 test_module_attach:FAIL:skel_load failed to load skeleton #81 module_attach:FAIL [0] https://github.com/kernel-patches/bpf/pull/1807/checks?check_run_id=3652765027 > v3: https://lore.kernel.org/bpf/20210915050943.679062-1-memxor@xxxxxxxxx > > * Address comments from Alexei > * Drop MAX_BPF_STACK change, instead move map_fd and BTF fd to BPF array map > and pass fd_array using BPF_PSEUDO_MAP_IDX_VALUE > * Address comments from Andrii > * Fix selftest to store to variable for observing function call instead of > printk and polluting CI logs > * Drop use of raw_tp for testing, instead reuse classifier based prog_test_run > * Drop index + 1 based insn->off convention for kfunc module calls > * Expand selftests to cover more corner cases > * Misc cleanups > > v2 -> v3 > v2: https://lore.kernel.org/bpf/20210914123750.460750-1-memxor@xxxxxxxxx > > * Fix issues pointed out by Kernel Test Robot > * Fix find_kfunc_desc to also take offset into consideration when comparing > > RFC v1 -> v2 > v1: https://lore.kernel.org/bpf/20210830173424.1385796-1-memxor@xxxxxxxxx > > * Address comments from Alexei > * Reuse fd_array instead of introducing kfunc_btf_fds array > * Take btf and module reference as needed, instead of preloading > * Add BTF_KIND_FUNC relocation support to gen_loader infrastructure > * Address comments from Andrii > * Drop hashmap in libbpf for finding index of existing BTF in fd_array > * Preserve invalid kfunc calls only when the symbol is weak > * Adjust verifier selftests > > Kumar Kartikeya Dwivedi (11): > bpf: Introduce BPF support for kernel module function calls > bpf: Be conservative while processing invalid kfunc calls > bpf: btf: Introduce helpers for dynamic BTF set registration > tools: Allow specifying base BTF file in resolve_btfids > bpf: Enable TCP congestion control kfunc from modules > libbpf: Support kernel module function calls > libbpf: Resolve invalid weak kfunc calls with imm = 0, off = 0 > libbpf: Update gen_loader to emit BTF_KIND_FUNC relocations > tools: bpftool: Add separate fd_array map support for light skeleton > libbpf: Fix skel_internal.h to set errno on loader retval < 0 > bpf: selftests: Add selftests for module kfunc support > > include/linux/bpf.h | 8 +- > include/linux/bpf_verifier.h | 2 + > include/linux/bpfptr.h | 1 + > include/linux/btf.h | 37 +++ > kernel/bpf/btf.c | 56 +++++ > kernel/bpf/core.c | 4 + > kernel/bpf/verifier.c | 220 ++++++++++++++--- > net/bpf/test_run.c | 7 +- > net/ipv4/bpf_tcp_ca.c | 36 +-- > net/ipv4/tcp_bbr.c | 28 ++- > net/ipv4/tcp_cubic.c | 26 +- > net/ipv4/tcp_dctcp.c | 26 +- > scripts/Makefile.modfinal | 1 + > tools/bpf/bpftool/gen.c | 3 +- > tools/bpf/bpftool/prog.c | 1 + > tools/bpf/resolve_btfids/main.c | 19 +- > tools/lib/bpf/bpf.c | 1 + > tools/lib/bpf/bpf_gen_internal.h | 16 +- > tools/lib/bpf/gen_loader.c | 222 +++++++++++++++--- > tools/lib/bpf/libbpf.c | 83 +++++-- > tools/lib/bpf/libbpf.h | 1 + > tools/lib/bpf/libbpf_internal.h | 1 + > tools/lib/bpf/skel_internal.h | 33 ++- > tools/testing/selftests/bpf/Makefile | 5 +- > .../selftests/bpf/bpf_testmod/bpf_testmod.c | 26 +- > .../selftests/bpf/prog_tests/ksyms_module.c | 52 ++-- > .../bpf/prog_tests/ksyms_module_libbpf.c | 44 ++++ > .../selftests/bpf/progs/test_ksyms_module.c | 41 +++- > .../bpf/progs/test_ksyms_module_fail.c | 29 +++ > .../progs/test_ksyms_module_fail_toomany.c | 19 ++ > .../bpf/progs/test_ksyms_module_libbpf.c | 71 ++++++ > .../bpf/progs/test_ksyms_module_util.h | 48 ++++ > 32 files changed, 1014 insertions(+), 153 deletions(-) > create mode 100644 tools/testing/selftests/bpf/prog_tests/ksyms_module_libbpf.c > create mode 100644 tools/testing/selftests/bpf/progs/test_ksyms_module_fail.c > create mode 100644 tools/testing/selftests/bpf/progs/test_ksyms_module_fail_toomany.c > create mode 100644 tools/testing/selftests/bpf/progs/test_ksyms_module_libbpf.c > create mode 100644 tools/testing/selftests/bpf/progs/test_ksyms_module_util.h > > -- > 2.33.0 >
