From 0515e5999a466dfe6e1924f460da599bb6821487 Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Thu, 1 Sep 2016 18:37:22 -0700 Subject: [PATCH] bpf: introduce BPF_PROG_TYPE_PERF_EVENT program type Introduce BPF_PROG_TYPE_PERF_EVENT programs that can be attached to HW and SW perf events (PERF_TYPE_HARDWARE and PERF_TYPE_SOFTWARE correspondingly in uapi/linux/perf_event.h) The program visible context meta structure is struct bpf_perf_event_data { struct pt_regs regs; __u64 sample_period; }; which is accessible directly from the program: int bpf_prog(struct bpf_perf_event_data *ctx) { ... ctx->sample_period ... ... ctx->regs.ip ... } The bpf verifier rewrites the accesses into kernel internal struct bpf_perf_event_data_kern which allows changing struct perf_sample_data without affecting bpf programs. New fields can be added to the end of struct bpf_perf_event_data in the future. Signed-off-by: Alexei Starovoitov Acked-by: Daniel Borkmann Signed-off-by: David S. Miller --- include/linux/perf_event.h | 5 +++ include/uapi/linux/Kbuild | 1 + include/uapi/linux/bpf.h | 1 + include/uapi/linux/bpf_perf_event.h | 18 +++++++++ kernel/trace/bpf_trace.c | 61 +++++++++++++++++++++++++++++ 5 files changed, 86 insertions(+) create mode 100644 include/uapi/linux/bpf_perf_event.h diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index 2b6b43cc0dd5..97bfe62f30d7 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -788,6 +788,11 @@ struct perf_output_handle { int page; }; +struct bpf_perf_event_data_kern { + struct pt_regs *regs; + struct perf_sample_data *data; +}; + #ifdef CONFIG_CGROUP_PERF /* diff --git a/include/uapi/linux/Kbuild b/include/uapi/linux/Kbuild index 185f8ea2702f..d0352a971ebd 100644 --- a/include/uapi/linux/Kbuild +++ b/include/uapi/linux/Kbuild @@ -71,6 +71,7 @@ header-y += binfmts.h header-y += blkpg.h header-y += blktrace_api.h header-y += bpf_common.h +header-y += bpf_perf_event.h header-y += bpf.h header-y += bpqether.h header-y += bsg.h diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index e4c5a1baa993..f896dfac4ac0 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -95,6 +95,7 @@ enum bpf_prog_type { BPF_PROG_TYPE_SCHED_ACT, BPF_PROG_TYPE_TRACEPOINT, BPF_PROG_TYPE_XDP, + BPF_PROG_TYPE_PERF_EVENT, }; #define BPF_PSEUDO_MAP_FD 1 diff --git a/include/uapi/linux/bpf_perf_event.h b/include/uapi/linux/bpf_perf_event.h new file mode 100644 index 000000000000..067427259820 --- /dev/null +++ b/include/uapi/linux/bpf_perf_event.h @@ -0,0 +1,18 @@ +/* Copyright (c) 2016 Facebook + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of version 2 of the GNU General Public + * License as published by the Free Software Foundation. + */ +#ifndef _UAPI__LINUX_BPF_PERF_EVENT_H__ +#define _UAPI__LINUX_BPF_PERF_EVENT_H__ + +#include +#include + +struct bpf_perf_event_data { + struct pt_regs regs; + __u64 sample_period; +}; + +#endif /* _UAPI__LINUX_BPF_PERF_EVENT_H__ */ diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index ad35213b8405..d3869b03d9fe 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -1,4 +1,5 @@ /* Copyright (c) 2011-2015 PLUMgrid, http://plumgrid.com + * Copyright (c) 2016 Facebook * * This program is free software; you can redistribute it and/or * modify it under the terms of version 2 of the GNU General Public @@ -8,6 +9,7 @@ #include #include #include +#include #include #include #include @@ -552,10 +554,69 @@ static struct bpf_prog_type_list tracepoint_tl = { .type = BPF_PROG_TYPE_TRACEPOINT, }; +static bool pe_prog_is_valid_access(int off, int size, enum bpf_access_type type, + enum bpf_reg_type *reg_type) +{ + if (off < 0 || off >= sizeof(struct bpf_perf_event_data)) + return false; + if (type != BPF_READ) + return false; + if (off % size != 0) + return false; + if (off == offsetof(struct bpf_perf_event_data, sample_period)) { + if (size != sizeof(u64)) + return false; + } else { + if (size != sizeof(long)) + return false; + } + return true; +} + +static u32 pe_prog_convert_ctx_access(enum bpf_access_type type, int dst_reg, + int src_reg, int ctx_off, + struct bpf_insn *insn_buf, + struct bpf_prog *prog) +{ + struct bpf_insn *insn = insn_buf; + + switch (ctx_off) { + case offsetof(struct bpf_perf_event_data, sample_period): + BUILD_BUG_ON(FIELD_SIZEOF(struct perf_sample_data, period) != sizeof(u64)); + *insn++ = BPF_LDX_MEM(bytes_to_bpf_size(FIELD_SIZEOF(struct bpf_perf_event_data_kern, data)), + dst_reg, src_reg, + offsetof(struct bpf_perf_event_data_kern, data)); + *insn++ = BPF_LDX_MEM(BPF_DW, dst_reg, dst_reg, + offsetof(struct perf_sample_data, period)); + break; + default: + *insn++ = BPF_LDX_MEM(bytes_to_bpf_size(FIELD_SIZEOF(struct bpf_perf_event_data_kern, regs)), + dst_reg, src_reg, + offsetof(struct bpf_perf_event_data_kern, regs)); + *insn++ = BPF_LDX_MEM(bytes_to_bpf_size(sizeof(long)), + dst_reg, dst_reg, ctx_off); + break; + } + + return insn - insn_buf; +} + +static const struct bpf_verifier_ops perf_event_prog_ops = { + .get_func_proto = tp_prog_func_proto, + .is_valid_access = pe_prog_is_valid_access, + .convert_ctx_access = pe_prog_convert_ctx_access, +}; + +static struct bpf_prog_type_list perf_event_tl = { + .ops = &perf_event_prog_ops, + .type = BPF_PROG_TYPE_PERF_EVENT, +}; + static int __init register_kprobe_prog_ops(void) { bpf_register_prog_type(&kprobe_tl); bpf_register_prog_type(&tracepoint_tl); + bpf_register_prog_type(&perf_event_tl); return 0; } late_initcall(register_kprobe_prog_ops); -- 2.30.2