| Message ID | 20250318143318.656785-1-aspsk@isovalent.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | instruction sets and static keys | expand |
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. > > 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 >
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 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