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132 lines
3.2 KiB
132 lines
3.2 KiB
/*
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* FollyRequestContextSwitch Monitor RequestContext switch events for any binary
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* uses the class from [folly](http://bit.ly/2h6S1yx).
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* For Linux, uses BCC, eBPF. Embedded C.
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*
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* Basic example of using USDT with BCC.
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*
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* USAGE: FollyRequestContextSwitch PATH_TO_BINARY
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*
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* Copyright (c) Facebook, Inc.
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* Licensed under the Apache License, Version 2.0 (the "License")
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*/
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#include <signal.h>
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#include <functional>
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#include <iostream>
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#include <vector>
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#include "BPF.h"
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const std::string BPF_PROGRAM = R"(
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#include <linux/sched.h>
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#include <uapi/linux/ptrace.h>
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struct event_t {
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int pid;
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char name[16];
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uint64_t old_addr;
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uint64_t new_addr;
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};
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BPF_PERF_OUTPUT(events);
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int on_context_switch(struct pt_regs *ctx) {
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struct event_t event = {};
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event.pid = bpf_get_current_pid_tgid();
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bpf_get_current_comm(&event.name, sizeof(event.name));
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bpf_usdt_readarg(1, ctx, &event.old_addr);
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bpf_usdt_readarg(2, ctx, &event.new_addr);
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events.perf_submit(ctx, &event, sizeof(event));
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return 0;
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}
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)";
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// Define the same struct to use in user space.
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struct event_t {
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int pid;
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char name[16];
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uint64_t old_addr;
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uint64_t new_addr;
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};
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void handle_output(void* cb_cookie, void* data, int data_size) {
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auto event = static_cast<event_t*>(data);
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std::cout << "PID " << event->pid << " (" << event->name << ") ";
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std::cout << "folly::RequestContext switch from " << event->old_addr << " to "
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<< event->new_addr << std::endl;
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}
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std::function<void(int)> shutdown_handler;
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void signal_handler(int s) { shutdown_handler(s); }
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int main(int argc, char** argv) {
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std::string binary;
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pid_t pid = -1;
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for (int i = 0; i < argc; i++) {
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if (strncmp(argv[i], "--pid", 5) == 0) {
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pid = std::stoi(argv[i + 1]);
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i++;
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continue;
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}
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if (strncmp(argv[i], "--binary", 8) == 0) {
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binary = argv[i + 1];
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i++;
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continue;
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}
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}
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if (pid <= 0 && binary.empty()) {
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std::cout << "Must specify at least one of binary or PID:" << std::endl
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<< "FollyRequestContextSwitch [--pid PID] [--binary BINARY]"
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<< std::endl;
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exit(1);
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}
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ebpf::USDT u(binary, pid, "folly", "request_context_switch_before",
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"on_context_switch");
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ebpf::BPF* bpf = new ebpf::BPF();
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auto init_res = bpf->init(BPF_PROGRAM, {}, {u});
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if (init_res.code() != 0) {
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std::cerr << init_res.msg() << std::endl;
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return 1;
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}
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auto attach_res = bpf->attach_usdt(u);
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if (attach_res.code() != 0) {
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std::cerr << attach_res.msg() << std::endl;
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return 1;
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} else {
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std::cout << "Attached to USDT " << u;
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}
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auto open_res = bpf->open_perf_buffer("events", &handle_output);
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if (open_res.code() != 0) {
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std::cerr << open_res.msg() << std::endl;
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return 1;
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}
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shutdown_handler = [&](int s) {
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std::cerr << "Terminating..." << std::endl;
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bpf->detach_usdt(u);
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delete bpf;
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exit(0);
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};
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signal(SIGINT, signal_handler);
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std::cout << "Started tracing, hit Ctrl-C to terminate." << std::endl;
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auto perf_buffer = bpf->get_perf_buffer("events");
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if (perf_buffer)
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while (true)
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// 100ms timeout
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perf_buffer->poll(100);
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return 0;
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}
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