1 use crate::prelude::*;
2 use crate::profiling_agent::ProfilingAgent;
3 use std::io::{self, BufWriter, Write};
4 use std::process;
5 use std::{fs::File, sync::Mutex};
6 
7 /// Process-wide perf map file. Perf only reads a unique file per process.
8 static PERFMAP_FILE: Mutex<Option<BufWriter<File>>> = Mutex::new(None);
9 
10 /// Interface for driving the creation of jitdump files
11 struct PerfMapAgent;
12 
13 /// Initialize a JitDumpAgent and write out the header.
14 pub fn new() -> Result<Box<dyn ProfilingAgent>> {
15     let mut file = PERFMAP_FILE.lock().unwrap();
16     if file.is_none() {
17         let filename = format!("/tmp/perf-{}.map", process::id());
18         *file = Some(BufWriter::new(File::create(filename)?));
19     }
20     Ok(Box::new(PerfMapAgent))
21 }
22 
23 impl PerfMapAgent {
24     fn make_line(writer: &mut dyn Write, name: &str, code: &[u8]) -> io::Result<()> {
25         // Format is documented here: https://github.com/torvalds/linux/blob/master/tools/perf/Documentation/jit-interface.txt
26         // Try our best to sanitize the name, since wasm allows for any utf8 string in there.
27         let sanitized_name = name.replace('\n', "_").replace('\r', "_");
28         write!(
29             writer,
30             "{:p} {:x} {}\n",
31             code.as_ptr(),
32             code.len(),
33             sanitized_name
34         )?;
35         writer.flush()?;
36         Ok(())
37     }
38 }
39 
40 impl ProfilingAgent for PerfMapAgent {
41     fn register_function(&self, name: &str, code: &[u8]) {
42         let mut file = PERFMAP_FILE.lock().unwrap();
43         let file = file.as_mut().unwrap();
44         if let Err(err) = Self::make_line(file, name, code) {
45             eprintln!("Error when writing import trampoline info to the perf map file: {err}");
46         }
47     }
48 }
49