diff options
| -rw-r--r-- | src/rt.rs | 62 |
1 files changed, 60 insertions, 2 deletions
@@ -3,16 +3,62 @@ //! This runtime supports adding code to executable pages and turn the added code into user //! specified function pointer. -use nix::sys::mman::{mmap, mprotect, munmap, MapFlags, ProtFlags}; - #[cfg(not(target_os = "linux"))] compile_error!("This runtime is only supported on linux"); +use nix::sys::mman::{mmap, mprotect, munmap, MapFlags, ProtFlags}; + +mod perf { + use std::fs; + use std::io::Write; + + /// Provide support for the simple [perf jit interface][perf-jit]. + /// + /// This allows a simple (static) jit runtime to generate meta data describing the generated + /// functions, which is used during post-processing by `perf report` to symbolize addresses + /// captured while executing jitted code. + /// + /// By the nature of this format, this can not be used for dynamic jit runtimes, which reuses + /// memory which previously contained jitted code. + /// + /// [perf-jit]: https://elixir.bootlin.com/linux/v6.6.6/source/tools/perf/Documentation/jit-interface.txt + pub(super) struct PerfMap { + file: std::fs::File, + } + + impl PerfMap { + /// Create an empty perf map file. + pub(super) fn new() -> Self { + let name = format!("/tmp/perf-{}.map", nix::unistd::getpid()); + let file = fs::OpenOptions::new() + .truncate(true) + .create(true) + .write(true) + .open(&name) + .unwrap_or_else(|_| panic!("Failed to open perf map file {}", &name)); + + PerfMap { file } + } + + /// Add an entry to the perf map file. + pub(super) fn add_entry(&mut self, start: usize, len: usize) { + // Each line has the following format, fields separated with spaces: + // START SIZE NAME + // + // START and SIZE are hex numbers without 0x. + // NAME is the rest of the line, so it could contain special characters. + writeln!(self.file, "{:x} {:x} jitfn_{:x}", start, len, start) + .expect("Failed to write PerfMap entry"); + } + } +} + /// A simple `mmap`ed runtime with executable pages. pub struct Runtime { buf: *mut u8, len: usize, idx: usize, + perf: Option<perf::PerfMap>, } impl Runtime { @@ -40,9 +86,16 @@ impl Runtime { buf, len: len.get(), idx: 0, + perf: None, } } + pub fn with_profile() -> Runtime { + let mut rt = Runtime::new(); + rt.perf = Some(perf::PerfMap::new()); + rt + } + /// Add the block of `code` to the runtime and a get function pointer of type `F`. /// /// # Panics @@ -83,6 +136,11 @@ impl Runtime { // Increment index to next free byte. self.idx += code.len(); + // Add perf map entry. + if let Some(map) = &mut self.perf { + map.add_entry(fn_start as usize, code.len()); + } + // Return function to newly added code. unsafe { Self::as_fn::<F>(fn_start) } } |