1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
|
/*
* FollyRequestContextSwitch Monitor RequestContext switch events for any binary
* uses the class from [folly](http://bit.ly/2h6S1yx).
* For Linux, uses BCC, eBPF. Embedded C.
*
* Basic example of using USDT with BCC.
*
* USAGE: FollyRequestContextSwitch PATH_TO_BINARY
*
* Copyright (c) Facebook, Inc.
* Licensed under the Apache License, Version 2.0 (the "License")
*/
#include <signal.h>
#include <functional>
#include <iostream>
#include <vector>
#include "BPF.h"
const std::string BPF_PROGRAM = R"(
#include <linux/sched.h>
#include <uapi/linux/ptrace.h>
struct event_t {
int pid;
char name[16];
uint64_t old_addr;
uint64_t new_addr;
};
BPF_PERF_OUTPUT(events);
int on_context_switch(struct pt_regs *ctx) {
struct event_t event = {};
event.pid = bpf_get_current_pid_tgid();
bpf_get_current_comm(&event.name, sizeof(event.name));
bpf_usdt_readarg(1, ctx, &event.old_addr);
bpf_usdt_readarg(2, ctx, &event.new_addr);
events.perf_submit(ctx, &event, sizeof(event));
return 0;
}
)";
// Define the same struct to use in user space.
struct event_t {
int pid;
char name[16];
uint64_t old_addr;
uint64_t new_addr;
};
void handle_output(void* cb_cookie, void* data, int data_size) {
auto event = static_cast<event_t*>(data);
std::cout << "PID " << event->pid << " (" << event->name << ") ";
std::cout << "folly::RequestContext switch from " << event->old_addr << " to "
<< event->new_addr << std::endl;
}
std::function<void(int)> shutdown_handler;
void signal_handler(int s) { shutdown_handler(s); }
int main(int argc, char** argv) {
std::string binary;
pid_t pid = -1;
for (int i = 0; i < argc; i++) {
if (strncmp(argv[i], "--pid", 5) == 0) {
pid = std::stoi(argv[i + 1]);
i++;
continue;
}
if (strncmp(argv[i], "--binary", 8) == 0) {
binary = argv[i + 1];
i++;
continue;
}
}
if (pid <= 0 && binary.empty()) {
std::cout << "Must specify at least one of binary or PID:" << std::endl
<< "FollyRequestContextSwitch [--pid PID] [--binary BINARY]"
<< std::endl;
exit(1);
}
ebpf::USDT u(binary, pid, "folly", "request_context_switch_before",
"on_context_switch");
ebpf::BPF* bpf = new ebpf::BPF();
auto init_res = bpf->init(BPF_PROGRAM, {}, {u});
if (init_res.code() != 0) {
std::cerr << init_res.msg() << std::endl;
return 1;
}
auto attach_res = bpf->attach_usdt_all();
if (attach_res.code() != 0) {
std::cerr << attach_res.msg() << std::endl;
return 1;
} else {
std::cout << "Attached to USDT " << u;
}
auto open_res = bpf->open_perf_buffer("events", &handle_output);
if (open_res.code() != 0) {
std::cerr << open_res.msg() << std::endl;
return 1;
}
shutdown_handler = [&](int s) {
std::cerr << "Terminating..." << std::endl;
bpf->detach_usdt_all();
delete bpf;
exit(0);
};
signal(SIGINT, signal_handler);
std::cout << "Started tracing, hit Ctrl-C to terminate." << std::endl;
auto perf_buffer = bpf->get_perf_buffer("events");
if (perf_buffer)
while (true)
// 100ms timeout
perf_buffer->poll(100);
return 0;
}
|
