On Wed, Dec 11, 2024 at 5:34 AM Jiri Olsa <jolsa@xxxxxxxxxx> wrote: > > hi, > this patchset adds support to optimize usdt probes on top of 5-byte > nop instruction. > > The generic approach (optimize all uprobes) is hard due to emulating > possible multiple original instructions and its related issues. The > usdt case, which stores 5-byte nop seems much easier, so starting > with that. > > The basic idea is to replace breakpoint exception with syscall which > is faster on x86_64. For more details please see changelog of patch 8. > > The run_bench_uprobes.sh benchmark triggers uprobe (on top of different > original instructions) in a loop and counts how many of those happened > per second (the unit below is million loops). > > There's big speed up if you consider current usdt implementation > (uprobe-nop) compared to proposed usdt (uprobe-nop5): > > # ./benchs/run_bench_uprobes.sh > > usermode-count : 233.831 ± 0.257M/s > syscall-count : 12.107 ± 0.038M/s > --> uprobe-nop : 3.246 ± 0.004M/s > uprobe-push : 3.057 ± 0.000M/s > uprobe-ret : 1.113 ± 0.003M/s > --> uprobe-nop5 : 6.751 ± 0.037M/s > uretprobe-nop : 1.740 ± 0.015M/s > uretprobe-push : 1.677 ± 0.018M/s > uretprobe-ret : 0.852 ± 0.005M/s > uretprobe-nop5 : 6.769 ± 0.040M/s uretprobe-nop5 throughput is the same as uprobe-nop5?.. > > > v1 changes: > - rebased on top of bpf-next/master > - couple of function/variable renames [Andrii] > - added nop5 emulation [Andrii] > - added checks to arch_uprobe_verify_opcode [Andrii] > - fixed arch_uprobe_is_callable/find_nearest_page [Andrii] > - used CALL_INSN_OPCODE [Masami] > - added uprobe-nop5 benchmark [Andrii] > - using atomic64_t in tramp_area [Andri] > - using single page for all uprobe trampoline mappings > > thanks, > jirka > > > --- > Jiri Olsa (13): > uprobes: Rename arch_uretprobe_trampoline function > uprobes: Make copy_from_page global > uprobes: Add nbytes argument to uprobe_write_opcode > uprobes: Add arch_uprobe_verify_opcode function > uprobes: Add mapping for optimized uprobe trampolines > uprobes/x86: Add uprobe syscall to speed up uprobe > uprobes/x86: Add support to emulate nop5 instruction > uprobes/x86: Add support to optimize uprobes > selftests/bpf: Use 5-byte nop for x86 usdt probes > selftests/bpf: Add uprobe/usdt optimized test > selftests/bpf: Add hit/attach/detach race optimized uprobe test > selftests/bpf: Add uprobe syscall sigill signal test > selftests/bpf: Add 5-byte nop uprobe trigger bench > > arch/x86/entry/syscalls/syscall_64.tbl | 1 + > arch/x86/include/asm/uprobes.h | 7 +++ > arch/x86/kernel/uprobes.c | 255 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++- > include/linux/syscalls.h | 2 + > include/linux/uprobes.h | 25 +++++++- > kernel/events/uprobes.c | 191 +++++++++++++++++++++++++++++++++++++++++++++++++++----- > kernel/fork.c | 1 + > kernel/sys_ni.c | 1 + > tools/testing/selftests/bpf/bench.c | 12 ++++ > tools/testing/selftests/bpf/benchs/bench_trigger.c | 42 +++++++++++++ > tools/testing/selftests/bpf/benchs/run_bench_uprobes.sh | 2 +- > tools/testing/selftests/bpf/prog_tests/uprobe_syscall.c | 326 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ > tools/testing/selftests/bpf/progs/uprobe_optimized.c | 29 +++++++++ > tools/testing/selftests/bpf/sdt.h | 9 ++- > 14 files changed, 880 insertions(+), 23 deletions(-) > create mode 100644 tools/testing/selftests/bpf/progs/uprobe_optimized.c
