From: "Björn Töpel" <firstname.lastname@example.org> To: email@example.com, firstname.lastname@example.org, email@example.com Cc: "Björn Töpel" <firstname.lastname@example.org>, email@example.com, firstname.lastname@example.org Subject: [PATCH bpf-next 0/8] riscv: BPF JIT fix, optimizations and far jumps support Date: Mon, 9 Dec 2019 18:31:28 +0100 [thread overview] Message-ID: <email@example.com> (raw) Hi! This series contain one non-critical fix, support for far jumps. and some optimizations for the BPF JIT. Previously, the JIT only supported 12b branch targets for conditional branches, and 21b for unconditional branches. Starting with this series, 32b branching is supported. As part of supporting far jumps, branch relaxation was introduced. The idea is to start with a pessimistic jump (e.g. auipc/jalr) and for each pass the JIT will have an opportunity to pick a better instruction (e.g. jal) and shrink the image. Instead of two passes, the JIT requires more passes. It typically converges after 3 passes. The optimizations mentioned in the subject are for calls and tail calls. In the tail call generation we can save one instruction by using the offset in jalr. Calls are optimized by doing (auipc)/jal(r) relative jumps instead of loading the entire absolute address and doing jalr. This required that the JIT image allocator was made RISC-V specific, so we can ensure that the JIT image and the kernel text are in range (32b). The last two patches of the series is not critical to the series, but are two UAPI build issues for BPF events. A closer look from the RV-folks would be much appreciated. The test_bpf.ko module and test_verifier from selftests pass all tests. RISC-V is still missing proper kprobe and tracepoint support, so a lot of BPF selftests cannot be run. Thanks, Björn Björn Töpel (8): riscv, bpf: fix broken BPF tail calls riscv, bpf: add support for far branching riscv, bpf: add support for far jumps and exits riscv, bpf: optimize BPF tail calls riscv, bpf: provide RISC-V specific JIT image alloc/free riscv, bpf: optimize calls riscv, bpf: add missing uapi header for BPF_PROG_TYPE_PERF_EVENT programs riscv, perf: add arch specific perf_arch_bpf_user_pt_regs arch/riscv/include/asm/perf_event.h | 4 + arch/riscv/include/asm/pgtable.h | 4 + arch/riscv/include/uapi/asm/bpf_perf_event.h | 9 + arch/riscv/net/bpf_jit_comp.c | 511 +++++++++++-------- tools/include/uapi/asm/bpf_perf_event.h | 2 + 5 files changed, 310 insertions(+), 220 deletions(-) create mode 100644 arch/riscv/include/uapi/asm/bpf_perf_event.h -- 2.20.1
next reply other threads:[~2019-12-09 17:31 UTC|newest] Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-12-09 17:31 Björn Töpel [this message] 2019-12-09 17:31 ` [PATCH bpf-next 1/8] riscv, bpf: fix broken BPF tail calls Björn Töpel 2019-12-09 17:31 ` [PATCH bpf-next 2/8] riscv, bpf: add support for far branching Björn Töpel 2019-12-09 21:08 ` Luke Nelson 2019-12-09 21:27 ` Daniel Borkmann 2019-12-10 7:02 ` Luke Nelson 2019-12-10 5:32 ` Björn Töpel 2019-12-10 5:31 ` Björn Töpel 2019-12-09 17:31 ` [PATCH bpf-next 3/8] riscv, bpf: add support for far jumps and exits Björn Töpel 2019-12-09 21:15 ` Luke Nelson 2019-12-09 17:31 ` [PATCH bpf-next 4/8] riscv, bpf: optimize BPF tail calls Björn Töpel 2019-12-09 17:31 ` [PATCH bpf-next 5/8] riscv, bpf: provide RISC-V specific JIT image alloc/free Björn Töpel 2019-12-09 17:31 ` [PATCH bpf-next 6/8] riscv, bpf: optimize calls Björn Töpel 2019-12-09 17:31 ` [PATCH bpf-next 7/8] riscv, bpf: add missing uapi header for BPF_PROG_TYPE_PERF_EVENT programs Björn Töpel 2019-12-09 17:31 ` [PATCH bpf-next 8/8] riscv, perf: add arch specific perf_arch_bpf_user_pt_regs Björn Töpel
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