On 25/03/18 02:00PM, Yonghong Song wrote: > > > On 3/18/25 7:33 AM, Anton Protopopov wrote: > > This patchset implements new type of map, instruction set, and uses > > it to build support for BPF static keys. The same map will be later > > used to provide support for indirect jumps and indirect calls. See > > [1], [2] for more context. > > > > Short table of contents: > > > > * patches 1, 9, 10, 11 are simple fixes (which can be sent > > independently, if acked) > > > > * patches 2, 3 add a new map type, BPF_MAP_TYPE_INSN_SET, and > > corresponding selftests. This map is used to track how original > > instructions were relocated into 'xlated' during the verification > > > > * patches 4, 5, 6, 7, 8 add support for static keys (kernel only) > > using (an extension) to that new map type. Only x86 support is > > added in this RFC > > > > * patches 12, 13, 14 add libbpf-side support for static keys and > > selftests > > > > It is RFC for a few reasons: > > > > 1) The kernel side of the static keys looks clear, however, the > > libbpf side is not _that_ clear. I thought that this is better to > > commit to a particular userspace design, as any particular design > > requires a lot of changes on the libbpf side. See patch 12 for > > the details > > > > 2) The libbpf part of the series requires a patched LLVM (see [3]), > > which adds support for gotol_or_nop/nop_or_gotol instructions, so > > selftests would not compile in CI. > > > > 3) Patch 4 adds support for a new BPF instruction. It looks > > reasonable to use an extended BPF_JMP|BPF_JA instruction, and not > > may_goto. Reasons: a follow up will add support for > > BPF_JMP|BPF_JA|BPF_X (indirect jumps), which also utilizes INSN_SET maps (see [2]). > > Then another follow up will add support CALL|BPF_X, for which there's > > no corresponding magic instruction (to be discussed at the following > > LSF/MM/BPF). > > > > Besides these reasons, there are some questions / known bugs, > > which will be fixed once the general plan is confirmed: > > > > * bpf_jit_blind_constants will patch code, which is ignored in this > > RFC series. The solution would be either moving tracking > > instruction sets to bpf_prog from the verifier environment, > > or moving bpf_jit_blind_constants upper the stack (right now, > > this is the first thing which every jit does, so maybe it can > > be actually executed from the verifier, and provide env context) > > > > * gen-loader not supported, fd_array usage in libbpf should be > > re-designed (see patch 12 for more details) > > > > * insn_off -> insn_set map mapping should be optimized (now it is > > brute force) > > > > Links: > > 1. http://oldvger.kernel.org/bpfconf2024_material/bpf_static_keys.pdf > > 2. https://lpc.events/event/18/contributions/1941/ > > 3. https://github.com/aspsk/llvm-project/tree/static-keys > > For llvm patch in [3], please remove changes in function isValidIdInMiddle() > as gotol_or_nop or nop_or_gotol will not appear in the *middle* of any > instruction. "gotol" should not be there either, I may remove it sometime > later. Thanks, removed. > > > > Anton Protopopov (14): > > bpf: fix a comment describing bpf_attr > > bpf: add new map type: instructions set > > selftests/bpf: add selftests for new insn_set map > > bpf: add support for an extended JA instruction > > bpf: Add kernel/bpftool asm support for new instructions > > bpf: add BPF_STATIC_KEY_UPDATE syscall > > bpf: save the start of functions in bpf_prog_aux > > bpf, x86: implement static key support > > selftests/bpf: add guard macros around likely/unlikely > > libbpf: add likely/unlikely macros > > selftests/bpf: remove likely/unlikely definitions > > libbpf: BPF Static Keys support > > libbpf: Add bpf_static_key_update() API > > selftests/bpf: Add tests for BPF static calls > > > > arch/x86/net/bpf_jit_comp.c | 65 +- > > include/linux/bpf.h | 28 + > > include/linux/bpf_types.h | 1 + > > include/linux/bpf_verifier.h | 2 + > > include/uapi/linux/bpf.h | 40 +- > > kernel/bpf/Makefile | 2 +- > > kernel/bpf/bpf_insn_set.c | 400 +++++++++++ > > kernel/bpf/core.c | 5 + > > kernel/bpf/disasm.c | 33 +- > > kernel/bpf/syscall.c | 28 + > > kernel/bpf/verifier.c | 94 ++- > > tools/include/uapi/linux/bpf.h | 40 +- > > tools/lib/bpf/bpf.c | 17 + > > tools/lib/bpf/bpf.h | 19 + > > tools/lib/bpf/bpf_helpers.h | 63 ++ > > tools/lib/bpf/libbpf.c | 362 +++++++++- > > tools/lib/bpf/libbpf.map | 1 + > > tools/lib/bpf/libbpf_internal.h | 3 + > > tools/lib/bpf/linker.c | 6 +- > > .../selftests/bpf/bpf_arena_spin_lock.h | 3 - > > .../selftests/bpf/prog_tests/bpf_insn_set.c | 639 ++++++++++++++++++ > > .../bpf/prog_tests/bpf_static_keys.c | 359 ++++++++++ > > .../selftests/bpf/progs/bpf_static_keys.c | 131 ++++ > > tools/testing/selftests/bpf/progs/iters.c | 2 - > > 24 files changed, 2315 insertions(+), 28 deletions(-) > > create mode 100644 kernel/bpf/bpf_insn_set.c > > create mode 100644 tools/testing/selftests/bpf/prog_tests/bpf_insn_set.c > > create mode 100644 tools/testing/selftests/bpf/prog_tests/bpf_static_keys.c > > create mode 100644 tools/testing/selftests/bpf/progs/bpf_static_keys.c > > >
