Merge pull request #991 from mkroening/instrument

feat: make ready for instrumentation

Author: mkroening

xtask/src/archive.rs

@@ -1,3 +1,4 @@
+use std::collections::HashSet;
 use std::env;
 use std::fmt::Write;
 use std::path::{Path, PathBuf};
@@ -41,21 +42,40 @@ impl Archive {
 		Ok(symbols)
 	}
 
-	pub fn retain_symbols<'a>(&self, symbols: impl Iterator<Item = &'a str>) -> Result<()> {
+	pub fn retain_symbols(&self, mut exported_symbols: HashSet<&str>) -> Result<()> {
 		let sh = crate::sh()?;
 		let archive = self.as_ref();
-		let prefix = archive.file_stem().unwrap().to_str().unwrap();
-
-		let symbol_renames = symbols.fold(String::new(), |mut output, symbol| {
-			let _ = writeln!(output, "{prefix}_{symbol} {symbol}");
-			output
-		});
+		let prefix = {
+			let file_stem = archive.file_stem().unwrap().to_str().unwrap();
+			file_stem.strip_prefix("lib").unwrap_or(file_stem)
+		};
+
+		let all_symbols = {
+			let nm = binutil("nm")?;
+			let stdout = cmd!(sh, "{nm} --export-symbols {archive}").output()?.stdout;
+			String::from_utf8(stdout)?
+		};
+
+		let symbol_renames = all_symbols
+			.lines()
+			.fold(String::new(), |mut output, symbol| {
+				if exported_symbols.remove(symbol) {
+					return output;
+				}
+
+				if let Some(symbol) = symbol.strip_prefix("_ZN") {
+					let prefix_len = prefix.len();
+					let _ = writeln!(output, "_ZN{symbol} _ZN{prefix_len}{prefix}{symbol}",);
+				} else {
+					let _ = writeln!(output, "{symbol} {prefix}_{symbol}");
+				}
+				output
+			});
 
 		let rename_path = archive.with_extension("redefine-syms");
 		sh.write_file(&rename_path, symbol_renames)?;
 
 		let objcopy = binutil("objcopy")?;
-		cmd!(sh, "{objcopy} --prefix-symbols={prefix}_ {archive}").run()?;
 		cmd!(sh, "{objcopy} --redefine-syms={rename_path} {archive}").run()?;
 
 		sh.remove_path(&rename_path)?;

xtask/src/build.rs

@@ -1,3 +1,4 @@
+use std::collections::HashSet;
 use std::env::{self, VarError};
 
 use anyhow::Result;
@@ -57,7 +58,7 @@ impl Build {
 		eprintln!("Exporting hermit-builtins symbols");
 		let builtins = self.cargo_build.artifact.builtins_archive();
 		let builtin_symbols = sh.read_file("hermit-builtins/exports")?;
-		builtins.retain_symbols(builtin_symbols.lines())?;
+		builtins.retain_symbols(builtin_symbols.lines().collect::<HashSet<_>>())?;
 
 		dist_archive.append(&builtins)?;
 
@@ -85,6 +86,7 @@ impl Build {
 
 		if self.instrument_mcount {
 			rustflags.push("-Zinstrument-mcount");
+			rustflags.push("-Cpasses=ee-instrument<post-inline>");
 		}
 
 		if self.randomize_layout {
@@ -103,6 +105,7 @@ impl Build {
 		let explicit_exports = [
 			"_start",
 			"__bss_start",
+			"mcount",
 			"runtime_entry",
 			// lwIP functions (C runtime)
 			"init_lwip",
@@ -118,7 +121,7 @@ impl Build {
 
 		let symbols = explicit_exports.chain(syscall_symbols.iter().map(String::as_str));
 
-		archive.retain_symbols(symbols)?;
+		archive.retain_symbols(symbols.collect::<HashSet<_>>())?;
 
 		Ok(())
 	}