Merge #99

99: Separate trace collection from trace decoding. r=ltratt a=vext01



Co-authored-by: Edd Barrett <[email protected]>

Cargo.toml

@@ -9,6 +9,8 @@ libc = "0.2.80"
 lazy_static = "1.4.0"
 tempfile = "3.1.0"
 phdrs = { git = "https://github.com/softdevteam/phdrs" }
+strum = { version = "0.24.1", features = ["derive", "strum_macros"] }
+strum_macros = "0.24.3"
 
 [build-dependencies]
 cc = "1.0.62"

build.rs

@@ -97,14 +97,19 @@ fn main() {
 
     let c_deps_dir = make_c_deps_dir();
     let c_deps_dir_s = c_deps_dir.display();
+    c_build.file("src/util.c");
 
-    // Check if we should build the perf_pt backend.
+    // Check if we should build the perf collector.
     if cfg!(all(target_os = "linux", target_arch = "x86_64"))
-        && feature_check("check_perf_pt.c", "check_perf_pt")
+        && feature_check("check_perf.c", "check_perf")
     {
-        c_build.file("src/backends/perf_pt/collect.c");
-        c_build.file("src/backends/perf_pt/decode.c");
-        c_build.file("src/backends/perf_pt/util.c");
+        c_build.file("src/collect/perf/collect.c");
+        println!("cargo:rustc-cfg=collector_perf");
+    }
+
+    // FIXME: libipt support is unconditionally built-in for now.
+    if cfg!(all(target_os = "linux", target_arch = "x86_64")) {
+        c_build.file("src/decode/libipt/decode.c");
 
         // Decide whether to build our own libipt.
         if let Ok(val) = env::var("IPT_PATH") {
@@ -133,13 +138,14 @@ fn main() {
             c_deps_dir_s
         ));
 
-        println!("cargo:rustc-cfg=perf_pt");
+        println!("cargo:rustc-cfg=decoder_libipt");
         if cpu_supports_pt() {
-            println!("cargo:rustc-cfg=perf_pt_test");
+            println!("cargo:rustc-cfg=decoder_libipt_test");
         }
         println!("cargo:rustc-link-lib=static=ipt");
     }
     c_build.include("src/util");
+    c_build.include("src"); // to find `hwtracer_private.h`.
     c_build.compile("hwtracer_c");
 
     // Additional circumstances under which to re-run this build.rs.

examples/simple_example.rs

@@ -1,14 +1,15 @@
-use hwtracer::backends::TracerBuilder;
 use hwtracer::Trace;
+use hwtracer::{collect::TraceCollectorBuilder, decode::TraceDecoderBuilder};
 use std::time::SystemTime;
 
 /// Prints the addresses of the first `qty` blocks in a trace along with it's name and
 /// computation result.
-fn print_trace(trace: &Box<dyn Trace>, name: &str, result: u32, qty: usize) {
-    let count = trace.iter_blocks().count();
+fn print_trace(trace: Box<dyn Trace>, name: &str, result: u32, qty: usize) {
+    let dec = TraceDecoderBuilder::new().build().unwrap();
+    let count = dec.iter_blocks(&*trace).count();
     println!("{}: num_blocks={}, result={}", name, count, result);
 
-    for (i, blk) in trace.iter_blocks().take(qty).enumerate() {
+    for (i, blk) in dec.iter_blocks(&*trace).take(qty).enumerate() {
         println!("  block {}: 0x{:x}", i, blk.unwrap().first_instr());
     }
     if count > qty {
@@ -29,21 +30,20 @@ fn work() -> u32 {
     res
 }
 
-/// Trace a simple computation loop.
+/// Collect and decode a trace for a simple computation loop.
 ///
 /// The results are printed to discourage the compiler from optimising the computation out.
 fn main() {
-    let mut bldr = TracerBuilder::new();
-    println!("Backend configuration: {:?}", bldr.config());
-    let mut thr_tracer = bldr.build().unwrap().thread_tracer();
+    let bldr = TraceCollectorBuilder::new();
+    let mut thr_col = bldr.build().unwrap().thread_collector();
 
     for i in 1..4 {
-        thr_tracer.start_tracing().unwrap_or_else(|e| {
-            panic!("Failed to start tracer: {}", e);
+        thr_col.start_collector().unwrap_or_else(|e| {
+            panic!("Failed to start collector: {}", e);
         });
         let res = work();
-        let trace = thr_tracer.stop_tracing().unwrap();
+        let trace = thr_col.stop_collector().unwrap();
         let name = format!("trace{}", i);
-        print_trace(&trace, &name, res, 10);
+        print_trace(trace, &name, res, 10);
     }
 }

feature_checks/check_perf.c

@@ -0,0 +1,8 @@
+#include <linux/perf_event.h>
+
+int
+check(void)
+{
+    // The perf configuration struct version that first supported Intel PT.
+    return PERF_ATTR_SIZE_VER5;
+}