mono/data/lock-decoder/LockTracerDecoder.cs

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Globalization;
using System.Runtime.InteropServices;


public enum Record {
	MustNotHoldAny,
	MustNotHoldOne,
	MustHoldOne,
	LockAcquired,
	LockReleased
}


public struct LockRecord {
	public SimLock lk;
	public string frame;

	public LockRecord (SimLock lk, string frame) {
		this.lk = lk;
		this.frame = frame;
	}
}

public class SimThread
{
	int thread;
	List <LockRecord> locks = new List <LockRecord> ();

	public SimThread (int t)
	{
		this.thread = t;
	}

	public bool HoldsLock (SimLock lk) {
		foreach (var l in locks) {
			if (l.lk == lk)
				return true;
		}
		return false;
	}


	public int HoldCount (SimLock lk) {
		int res = 0;
		foreach (var l in locks)
			if (l.lk == lk)
				++res;
		return res;
	}

	public void Lock (SimLock lk, string frame) {
		foreach (LockRecord lr in locks) {
			if (lk.WarnAbout (this, lr.lk)) 
				Console.WriteLine ("WARNING: tried to acquire lock {0} at {1} while holding {2} at {3}: {4}", lk, frame, lr.lk, lr.frame, lk.GetWarningMessage (this, lr.lk));
			else if (!lk.IsValid (this, lr.lk))
				Console.WriteLine ("ERROR: tried to acquire lock {0} at {1} while holding {2} at {3}: {4}", lk, frame, lr.lk, lr.frame, lk.GetErrorMessage (this, lr.lk));
		}
		locks.Add (new LockRecord (lk, frame));
	}

	public void Release (SimLock lk, string frame) {
		if (locks.Count == 0) {
			Console.WriteLine ("ERROR: released lock {0} at {1} while holding no locks!", lk, frame);
			return;
		}
		LockRecord top = locks [locks.Count - 1];
		if (top.lk != lk && !(lk.IsGlobalLock && HoldCount (lk) > 1)) {
			Console.WriteLine ("WARNING: released lock {0} at {1} out of order with {2} at {3}!", lk, frame, top.lk, top.frame);
		}
		for (int i = locks.Count -1; i >= 0; --i) {
			if (locks [i].lk == lk) {
				locks.RemoveAt (i);
				break;
			}
		}
	}
}

/*
LOCK RULES

Simple locks:
 	Can be acquired at any point regardless of which locks are taken or not.
	No other locks can be acquired or released while holding a simple lock.
	Reentrancy is not recomended. (warning)
	Simple locks are leaf locks on the lock lattice.

Complex locks:
	Must respect locking order, which form a lattice.
	IOW, to take a given lock, only it's parents might have been taken.
	Reentrancy is ok.
	Locks around resources count as separate instances of the hierarchy.

Global locks:
	Must respect locking order.
	Must be the at the botton of the locking lattice.
	Can be taken out-of-order by other locks given that it was previously acquired.
	Adding global locks is not to be taken lightly.

The current lock hierarchy:
loader lock
	domain lock
		domain jit lock
			simple locks

Examples:
	You can take the loader lock without holding a domain lock.
	You cannot take a domain lock if the loader lock is held.
	You cannot take a domain lock while holding the lock to another domain.
*/

public enum Lock {
	Invalid,
	LoaderLock,
	ImageDataLock,
	DomainLock,
	DomainAssembliesLock,
	DomainJitCodeHashLock,
}

public class SimLock
{
	Lock kind;
	int id;

	public SimLock (Lock kind, int id) {
		this.kind = kind;
		this.id = id;
	}

	static int GetLockOrder (Lock kind) {
		switch (kind) {
			case Lock.LoaderLock:
				return 0;
			case Lock.DomainLock:
				return 1;
			case Lock.DomainJitCodeHashLock:
				return 2;
			default:
				return 3;
		}
	}

	bool IsParent (SimLock other) {
		return GetLockOrder (kind) > GetLockOrder (other.kind);
	}

	public bool IsSimpleLock {
		get { return GetLockOrder (kind) == 3; }
	}

	public bool IsGlobalLock {
		get { return kind == Lock.LoaderLock; }
	}

	/*locked is already owned by the thread, 'this' is the new one*/
	bool Compare (SimThread thread, SimLock locked, out bool isWarning, out string msg)
	{
		isWarning = false;
		msg = null;

		if (locked != this) {
			if (!IsParent (locked)) {
				if (IsGlobalLock) { /*acquiring a global lock*/
					if (!thread.HoldsLock (this)) { /*does the thread alread hold it?*/
						msg = "Acquired a global lock after a regular lock without having it before.";
						return false;
					}
				} else {
					msg = "Hierarchy violation.";
					return false;
				}
			}
		} else if (IsSimpleLock) {
			msg = "Avoid taking simple locks recursively";
			isWarning = true;
			return false;
		}

		return true;
	}

	public bool IsValid (SimThread thread, SimLock locked) {
		bool warn;
		string msg;
		return Compare (thread, locked, out warn, out msg);
	}

	public bool WarnAbout (SimThread thread, SimLock locked) {
		bool warn;
		string msg;
		Compare (thread, locked, out warn, out msg);
		return warn;
	}

	public string GetWarningMessage (SimThread thread, SimLock locked) {
		bool warn;
		string msg;
		Compare (thread, locked, out warn, out msg);
		return warn ? msg : null;
	}

	public string GetErrorMessage (SimThread thread, SimLock locked) {
		bool warn;
		string msg;
		bool res = Compare (thread, locked, out warn, out msg);
		return !res && !warn ? msg : null;
	}

	public override string ToString () {
		return String.Format ("{0}", kind);
	}
}

public class LockSimulator
{
	static Dictionary <int, SimThread> threads = new Dictionary <int, SimThread> ();
	static Dictionary <int, SimLock> locks = new Dictionary <int, SimLock> ();

	SymbolTable syms;

	public LockSimulator (SymbolTable s) { this.syms = s; }

	SimLock GetLock (Trace t)  {
		if (locks.ContainsKey (t.lockPtr))
			return locks [t.lockPtr];
		else {
			return locks [t.lockPtr] = new SimLock (t.lockKind, t.lockPtr);
		}
	}

	SimThread GetThread (Trace t) {
		if (threads.ContainsKey (t.thread))
			return threads [t.thread];
		else
			return threads [t.thread] = new SimThread (t.thread);		
	}

	public void PlayBack (IEnumerable<Trace> traces) {
		foreach (var t in traces) {
			SimThread thread = GetThread (t);
			SimLock lk = GetLock (t);
			string frame = t.GetUsefullTopTrace (this.syms);

			switch (t.record) {
			case Record.MustNotHoldAny:
			case Record.MustNotHoldOne:
			case Record.MustHoldOne:
				throw new Exception ("not supported");
			case Record.LockAcquired:
				thread.Lock (lk, frame);
				break;
			case Record.LockReleased:
				thread.Release (lk, frame);
				break;
			default:
				throw new Exception ("Invalid trace record: "+t.record);
			}
		}
	}
}

public class Trace {
	public int thread;
	public Record record;
	public Lock lockKind;
	public int lockPtr;
	int[] frames;

	static readonly string[] BAD_FRAME_METHODS = new string[] {
		"mono_loader_lock",
		"mono_loader_unlock",
		"mono_image_lock",
		"mono_image_unlock",
	};

	public Trace (string[] fields) {
		thread = fields [0].ParseHex ();
		record = (Record)fields [1].ParseDec ();
		lockKind = (Lock)fields [2].ParseDec ();
		lockPtr = fields [3].ParseHex ();
		frames = new int [fields.Length - 4];
		for (int i = 0; i < frames.Length; ++i)
			frames [i] = fields [i + 4].ParseHex ();
	}

	public void Dump (SymbolTable table) {
		Console.WriteLine ("{0:x} {1} {2} {3:x}", thread, record, lockKind, lockPtr);
		for (int i = 0; i < frames.Length; ++i)
			Console.WriteLine ("\t{0}", table.Translate (frames [i]));
	}

	public string GetUsefullTopTrace (SymbolTable syms) {
		for (int i = 0; i < frames.Length; ++i) {
			string str = syms.Translate (frames [i]);
			bool ok = true;
			for (int j = 0; j < BAD_FRAME_METHODS.Length; ++j) {
				if (str.IndexOf (BAD_FRAME_METHODS [j]) >= 0) {
					ok = false;
					break;
				}
			}
			if (ok)
				return str;
		}
		return "[unknown]";
	}
}

public class Symbol : IComparable<Symbol>
{
	public int offset;
	public int size;
	public string name;

	public Symbol (int o, int size, string n) {
		this.offset = o;
		this.size = size;
		this.name = n;
	}

	public int CompareTo(Symbol other) {
		return offset - other.offset;
	}
}

public interface SymbolTable {
	string Translate (int offset);
}

public class OsxSymbolTable : SymbolTable
{
	Symbol[] table;

	const int MAX_FUNC_SIZE = 0x20000;

	public OsxSymbolTable (string binary) {
		Load (binary);
	}

	void Load (string binary) {
		ProcessStartInfo psi = new ProcessStartInfo ("gobjdump", "-t "+binary);
		psi.UseShellExecute = false;
		psi.RedirectStandardOutput = true;

		var proc = Process.Start (psi);
		var list = new List<Symbol> ();
		string line;
		while ((line = proc.StandardOutput.ReadLine ()) != null) {
			string[] fields = line.Split(new char[] {' ', '\t'}, StringSplitOptions.RemoveEmptyEntries);
			if (fields.Length < 4)
				continue;
			if (!(fields [1].Equals ("g") || fields [1].Equals ("d")))
				continue;
			if (!fields [2].Equals ("*UND*"))
				continue;

			int offset = fields [0].ParseHex ();
			string name = fields [3];
			if (offset != 0)
				list.Add (new Symbol (offset, 0, name));
		}
		table = new Symbol [list.Count];
		list.CopyTo (table, 0);
		Array.Sort (table);
	}

	public string Translate (int offset) {
		Symbol sym = null;
		int res = Array.BinarySearch (table, new Symbol (offset, 0, null));
		if (res >= 0)
			return table [res].name;
		res = ~res;

		if (res >= table.Length)
			sym = table [table.Length - 1];
		else if (res != 0)
			sym = table [res - 1];

		
		if (sym != null) {
			int size = Math.Max (sym.size, 10);
			if (offset - sym.offset < size)
				return sym.name;
		}
		return String.Format ("[{0:x}]", offset);
	}
}

public class LinuxSymbolTable : SymbolTable
{
	Symbol[] table;

	const int MAX_FUNC_SIZE = 0x20000;

	public LinuxSymbolTable (string binary) {
		Load (binary);
	}

	void Load (string binary) {
		ProcessStartInfo psi = new ProcessStartInfo ("objdump", "-t "+binary);
		psi.UseShellExecute = false;
		psi.RedirectStandardOutput = true;

		var proc = Process.Start (psi);
		var list = new List<Symbol> ();
		string line;
		while ((line = proc.StandardOutput.ReadLine ()) != null) {
			string[] fields = line.Split(new char[] {' ', '\t'}, StringSplitOptions.RemoveEmptyEntries);

			if (fields.Length < 6)
				continue;
			if (fields [3] != ".text" || fields [2] != "F")
				continue;

			int offset = fields [0].ParseHex ();
			int size = fields [4].ParseHex ();
			string name = fields [fields.Length - 1];
			if (offset != 0)
				list.Add (new Symbol (offset, size, name));
		}
		table = new Symbol [list.Count];
		list.CopyTo (table, 0);
		Array.Sort (table);
	}

	public string Translate (int offset) {
		Symbol sym = null;
		int res = Array.BinarySearch (table, new Symbol (offset, 0, null));
		if (res >= 0)
			return table [res].name;
		res = ~res;

		if (res >= table.Length)
			sym = table [table.Length - 1];
		else if (res != 0)
			sym = table [res - 1];

		if (sym != null && offset - sym.offset < MAX_FUNC_SIZE)
			return sym.name;
		return String.Format ("[{0:x}]", offset);
	}
}

public class TraceDecoder
{
	string file;

	public TraceDecoder (string file) {
		this.file = file;
	}

	public IEnumerable<Trace> GetTraces () {
		using (StreamReader reader = new StreamReader (file)) {
			string line;
			while ((line = reader.ReadLine ()) != null) {
				string[] fields = line.Split(new char[] {','}, StringSplitOptions.RemoveEmptyEntries);
				if (fields.Length >= 7) {
					yield return new Trace (fields);
				}
			}
		}
	}
}

public class Driver
{
	[DllImport ("libc")]
	static extern int uname (IntPtr buf);

	static bool IsOSX ()
	{
		bool isOsx = false;
		IntPtr buf = Marshal.AllocHGlobal (8192);
		if (uname (buf) == 0) {
			string os = Marshal.PtrToStringAnsi (buf);
			isOsx = os == "Darwin";
		}

		Marshal.FreeHGlobal (buf);
		return isOsx;
	}


	static void Main (string[] args) {
		SymbolTable syms;
		if (args.Length != 2) {
			Console.WriteLine ("usage: LockTracerDecoder.exe /path/to/mono /path/to/locks.pid");
			return;
		}
		if (IsOSX ())
			syms = new OsxSymbolTable (args [0]);
		else
			syms = new LinuxSymbolTable (args [0]);

		var decoder = new TraceDecoder (args [1]);
		var sim = new LockSimulator (syms);
		sim.PlayBack (decoder.GetTraces ());
	}
}

public static class Utils
{
	public static int ParseHex (this string number) {
		while (number.Length > 1 && (number [0] == '0' || number [0] == 'x' || number [0] == 'X'))
			number = number.Substring (1);
		return int.Parse (number, NumberStyles.HexNumber);
	}

	public static int ParseDec (this string number) {
		while (number.Length > 1 && number [0] == '0')
			number = number.Substring (1);
		return int.Parse (number);
	}
}