| Message ID | 20210920141526.3940002-1-memxor@gmail.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | Support kernel module function calls from eBPF | expand |
On Mon, Sep 20, 2021 at 7:15 AM Kumar Kartikeya Dwivedi <memxor@gmail.com> 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@gmail.com > > * 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@gmail.com > > * 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@gmail.com > > * 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 >
On Tue, Sep 21, 2021 at 05:59:22AM IST, Andrii Nakryiko wrote: > On Mon, Sep 20, 2021 at 7:15 AM Kumar Kartikeya Dwivedi > <memxor@gmail.com> 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]): > I'll look into it. There were some problems getting it to run on Arch and Fedora, so I instead tested in my own VM (GLIBC_2.33 not found). Surprisingly, everything passed when I ran it before sending. e.g. I still get this for the two failing tests in CI. [root@(none) bpf]# ./test_progs -t ksyms_module_libbpf #66 ksyms_module_libbpf:OK Summary: 1/0 PASSED, 0 SKIPPED, 0 FAILED [root@(none) bpf]# ./test_progs -t module_attach #81 module_attach:OK Summary: 1/0 PASSED, 0 SKIPPED, 0 FAILED -- Kartikeya
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 v3: https://lore.kernel.org/bpf/20210915050943.679062-1-memxor@gmail.com * 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@gmail.com * 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@gmail.com * 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