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authorAlexei Starovoitov <ast@fb.com>2016-09-01 18:37:22 -0700
committerDavid S. Miller <davem@davemloft.net>2016-09-02 10:46:44 -0700
commit0515e5999a466dfe6e1924f460da599bb6821487 (patch)
treee4ba954bea80d223248c57885019b7620375164a /kernel
parentea2e7ce5d0fc878463ba39deb46cf2ab20398fd2 (diff)
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 <ast@kernel.org> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/trace/bpf_trace.c61
1 files changed, 61 insertions, 0 deletions
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 <linux/types.h>
#include <linux/slab.h>
#include <linux/bpf.h>
+#include <linux/bpf_perf_event.h>
#include <linux/filter.h>
#include <linux/uaccess.h>
#include <linux/ctype.h>
@@ -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);