7 files changed, 751 insertions, 11 deletions

diff --git a/mps/code/lii4gc.gmk b/mps/code/lii4gc.gmk
index 2eceecb9827..6ed66a21f85 100644
--- a/mps/code/lii4gc.gmk
+++ b/mps/code/lii4gc.gmk
@@ -5,7 +5,7 @@
 
 PFM = lii4gc
 
-THREADSRC = lockli.c thlii4.c pthrdext.c
+THREADSRC = lockli.c thli.c pthrdext.c
 THREADLIB = -lpthread
 
 # _XOPEN_SOURCE is to get the modern POSIX signal handling
diff --git a/mps/code/lii6gc.gmk b/mps/code/lii6gc.gmk
new file mode 100644
index 00000000000..d072f5f62fd
--- /dev/null
+++ b/mps/code/lii6gc.gmk
@@ -0,0 +1,71 @@
+# lii6gc.gmk: BUILD FOR LINUX/x64/GCC PLATFORM
+#
+# $Id$
+# Copyright (c) 2001 Ravenbrook Limited.  See end of file for license.
+
+PFM = lii6gc
+
+THREADSRC = lockli.c thli.c pthrdext.c
+THREADLIB = -lpthread
+
+# _XOPEN_SOURCE is to get the modern POSIX signal handling
+# _GNU_SOURCE is to get register numbers in prmci3li.c
+PFMDEFS = -D_REENTRANT -D_XOPEN_SOURCE=500 -D_GNU_SOURCE
+
+MPMPF = ${THREADSRC} vmix.c \
+        protix.c protlii6.c proti6.c prmci6li.c ssixi6.c span.c
+SWPF = than.c vmli.c protsw.c prmcan.c ssan.c
+
+LIBS = -lm ${THREADLIB}
+
+include gc.gmk
+
+CC = cc
+
+# Suppress some warnings (SuSE).
+#   .void: -Wpointer-arith cannot be used because the string.h header does
+#   arithmetic on void*.
+CFLAGSCOMPILER := -pthread $(subst -Wpointer-arith,,$(CFLAGSCOMPILER))
+
+include comm.gmk
+
+
+# C. COPYRIGHT AND LICENSE
+#
+# Copyright (C) 2001-2002 Ravenbrook Limited <http://www.ravenbrook.com/>.
+# All rights reserved.  This is an open source license.  Contact
+# Ravenbrook for commercial licensing options.
+# 
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+# 
+# 1. Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+# 
+# 2. Redistributions in binary form must reproduce the above copyright
+# notice, this list of conditions and the following disclaimer in the
+# documentation and/or other materials provided with the distribution.
+# 
+# 3. Redistributions in any form must be accompanied by information on how
+# to obtain complete source code for this software and any accompanying
+# software that uses this software.  The source code must either be
+# included in the distribution or be available for no more than the cost
+# of distribution plus a nominal fee, and must be freely redistributable
+# under reasonable conditions.  For an executable file, complete source
+# code means the source code for all modules it contains. It does not
+# include source code for modules or files that typically accompany the
+# major components of the operating system on which the executable file
+# runs.
+# 
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
+# IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+# TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
+# PURPOSE, OR NON-INFRINGEMENT, ARE DISCLAIMED. IN NO EVENT SHALL THE
+# COPYRIGHT HOLDERS AND CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+# NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
+# USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
+# ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+# THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
diff --git a/mps/code/mpstd.h b/mps/code/mpstd.h
index 4a8a0875ca3..86b89c836f5 100644
--- a/mps/code/mpstd.h
+++ b/mps/code/mpstd.h
@@ -470,6 +470,23 @@
 #define MPS_WORD_SHIFT  5
 #define MPS_PF_ALIGN    4
 
+/* GCC 4.6.3, gcc -E -dM */
+
+#elif defined(__linux__) && defined(__x86_64) && defined(__GNUC__)
+#if defined(CONFIG_PF_STRING) && ! defined(CONFIG_PF_LII6GC)
+#error "specified CONFIG_PF_... inconsistent with detected lii6gc"
+#endif
+#define MPS_PF_LII6GC
+#define MPS_PF_STRING   "lii6gc"
+#define MPS_OS_LI
+#define MPS_ARCH_I6
+#define MPS_BUILD_GC
+#define MPS_T_WORD      unsigned long
+#define MPS_T_ULONGEST  unsigned long
+#define MPS_WORD_WIDTH  64
+#define MPS_WORD_SHIFT  6
+#define MPS_PF_ALIGN    8
+
 /* GCC 2.7.2, gcc -E -dM */
 
 #elif defined(__linux__) && defined(__PPC__) && defined(__GNUC__)
diff --git a/mps/code/prmci6li.c b/mps/code/prmci6li.c
new file mode 100644
index 00000000000..e81a7cfd750
--- /dev/null
+++ b/mps/code/prmci6li.c
@@ -0,0 +1,123 @@
+/* prmci6li.c: PROTECTION MUTATOR CONTEXT x64 (LINUX)
+ *
+ * $Id$
+ * Copyright (c) 2001 Ravenbrook Limited.  See end of file for license.
+ *
+ * .purpose: This module implements the part of the protection module
+ * that decodes the MutatorFaultContext. 
+ *
+ *
+ * SOURCES
+ *
+ * .source.linux.kernel: Linux kernel source files.
+ *
+ *
+ * ASSUMPTIONS
+ *
+ * .assume.regref: The resisters in the context can be modified by
+ * storing into an MRef pointer.
+ */
+
+#include "prmcix.h"
+#include "prmci6.h"
+
+SRCID(prmci6li, "$Id$");
+
+
+/* Prmci6AddressHoldingReg -- return an address of a register in a context */
+
+MRef Prmci6AddressHoldingReg(MutatorFaultContext mfc, unsigned int regnum)
+{
+  Word *gregs;
+
+  AVER(regnum <= 15);
+  AVER(regnum >= 0);
+
+  gregs = (Word *)&mfc->ucontext->uc_mcontext.gregs;
+
+  /* .assume.regref */
+  /* The REG_EAX etc. symbols are only present if _GNU_SOURCE is defined.
+   * Currently this is in lii6gc.gmk in PFMDEFS. */
+  switch (regnum) {
+    case  0: return &gregs[REG_RAX];
+    case  1: return &gregs[REG_RCX];
+    case  2: return &gregs[REG_RDX];
+    case  3: return &gregs[REG_RBX];
+    case  4: return &gregs[REG_RSP];
+    case  5: return &gregs[REG_RBP];
+    case  6: return &gregs[REG_RSI];
+    case  7: return &gregs[REG_RDI];
+    case  8: return &gregs[REG_R8];
+    case  9: return &gregs[REG_R9];
+    case 10: return &gregs[REG_R10];
+    case 11: return &gregs[REG_R11];
+    case 12: return &gregs[REG_R12];
+    case 13: return &gregs[REG_R13];
+    case 14: return &gregs[REG_R14];
+    case 15: return &gregs[REG_R15];
+  }
+  NOTREACHED;
+  return (MRef)NULL;  /* Avoids compiler warning. */
+}
+
+
+/* Prmci3DecodeFaultContext -- decode fault to find faulting address and IP */
+
+void Prmci6DecodeFaultContext(MRef *faultmemReturn,
+                              Byte **insvecReturn,
+                              MutatorFaultContext mfc)
+{
+  /* .source.linux.kernel (linux/arch/x86/mm/fault.c). */
+  *faultmemReturn = (MRef)mfc->info->si_addr;
+  *insvecReturn = (Byte*)mfc->ucontext->uc_mcontext.gregs[REG_RIP];
+}
+
+
+/* Prmci3StepOverIns -- modify context to step over instruction */
+
+void Prmci6StepOverIns(MutatorFaultContext mfc, Size inslen)
+{
+  mfc->ucontext->uc_mcontext.gregs[REG_RIP] += (Word)inslen;
+}
+
+
+/* C. COPYRIGHT AND LICENSE
+ *
+ * Copyright (C) 2001-2002 Ravenbrook Limited <http://www.ravenbrook.com/>.
+ * All rights reserved.  This is an open source license.  Contact
+ * Ravenbrook for commercial licensing options.
+ * 
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ * 
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 
+ * 3. Redistributions in any form must be accompanied by information on how
+ * to obtain complete source code for this software and any accompanying
+ * software that uses this software.  The source code must either be
+ * included in the distribution or be available for no more than the cost
+ * of distribution plus a nominal fee, and must be freely redistributable
+ * under reasonable conditions.  For an executable file, complete source
+ * code means the source code for all modules it contains. It does not
+ * include source code for modules or files that typically accompany the
+ * major components of the operating system on which the executable file
+ * runs.
+ * 
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
+ * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+ * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
+ * PURPOSE, OR NON-INFRINGEMENT, ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT HOLDERS AND CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
+ * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
+ * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
diff --git a/mps/code/protlii6.c b/mps/code/protlii6.c
new file mode 100644
index 00000000000..e149d5269ed
--- /dev/null
+++ b/mps/code/protlii6.c
@@ -0,0 +1,180 @@
+/* protlii6.c: PROTECTION FOR LINUX (x64)
+ *
+ *  $Id$
+ *  Copyright (c) 2001 Ravenbrook Limited.  See end of file for license.
+ *
+ * SOURCES
+ *
+ * .source.linux.kernel: Linux kernel source files.
+ */
+
+#include "prmcix.h"
+
+#ifndef MPS_OS_LI
+#error "protlii6.c is Linux-specific, but MPS_OS_LI is not set"
+#endif
+#if !defined(MPS_ARCH_I6)
+#error "protlii6.c is x64, but MPS_ARCH_I6 is not set"
+#endif
+#ifndef PROTECTION
+#error "protlii6.c implements protection, but PROTECTION is not set"
+#endif
+
+#include <limits.h>
+#include <stddef.h>
+#include <stdlib.h>
+#include <signal.h>
+#include <unistd.h>
+
+SRCID(protlii6, "$Id$");
+
+
+
+/* The previously-installed signal action, as returned by */
+/* sigaction(3).  See ProtSetup. */
+
+static struct sigaction sigNext;
+
+
+/* sigHandle -- protection signal handler
+ *
+ *  This is the signal handler installed by ProtSetup to deal with
+ *  protection faults.  It is installed on the SIGSEGV signal.
+ *  It decodes the protection fault details from the signal context
+ *  and passes them to ArenaAccess, which attempts to handle the
+ *  fault and remove its cause.  If the fault is handled, then
+ *  the handler returns and execution resumes.  If it isn't handled,
+ *  then sigHandle does its best to pass the signal on to the
+ *  previously installed signal handler (sigNext).
+ *
+ *  .sigh.context: We check si_code for being a memory access
+ *  si_addr gives the fault address.  See 
+ *  .source.linux.kernel (linux/arch/x86/mm/fault.c).
+ *
+ *  .sigh.addr: We assume that the OS decodes the address to something
+ *  sensible
+ */
+/* This is defined here to keep the sources closer to those in protsgix.c
+ * They can't be merged yet because protsgix doesn't pass the context to
+ * ArenaAccess */
+
+#define PROT_SIGNAL SIGSEGV
+
+static void sigHandle(int sig, siginfo_t *info, void *context)  /* .sigh.args */
+{
+  int e;
+  /* sigset renamed to asigset due to clash with global on Darwin. */
+  sigset_t asigset, oldset;
+  struct sigaction sa;
+
+  AVER(sig == PROT_SIGNAL);
+
+  if(info->si_code == SEGV_ACCERR) {  /* .sigh.context */
+    AccessSet mode;
+    Addr base;
+    ucontext_t *ucontext;
+    MutatorFaultContextStruct mfContext;
+
+    ucontext = (ucontext_t *)context;
+    mfContext.ucontext = ucontext;
+    mfContext.info = info;
+
+    /* on linux we used to be able to tell whether this was a read or a write */
+    mode = AccessREAD | AccessWRITE;
+
+    /* We assume that the access is for one word at the address. */
+    base = (Addr)info->si_addr;   /* .sigh.addr */
+    /* limit = AddrAdd(base, (Size)sizeof(Addr)); */
+
+    /* Offer each protection structure the opportunity to handle the */
+    /* exception.  If it succeeds, then allow the mutator to continue. */
+
+    if(ArenaAccess(base, mode, &mfContext))
+      return;
+  }
+
+  /* The exception was not handled by any known protection structure, */
+  /* so throw it to the previously installed handler.  That handler won't */
+  /* get an accurate context (the MPS would fail if it were the second in */
+  /* line) but it's the best we can do. */
+
+  e = sigaction(PROT_SIGNAL, &sigNext, &sa);
+  AVER(e == 0);
+  sigemptyset(&asigset);
+  sigaddset(&asigset, PROT_SIGNAL);
+  e = sigprocmask(SIG_UNBLOCK, &asigset, &oldset);
+  AVER(e == 0);
+  kill(getpid(), PROT_SIGNAL);
+  e = sigprocmask(SIG_SETMASK, &oldset, NULL);
+  AVER(e == 0);
+  e = sigaction(PROT_SIGNAL, &sa, NULL);
+  AVER(e == 0);
+}
+
+
+/*  ProtSetup -- global protection setup
+ *
+ *  Under Linux, the global setup involves installing a signal handler
+ *  on SIGSEGV to catch and handle page faults (see sigHandle).
+ *  The previous handler is recorded so that it can be reached from
+ *  sigHandle if it fails to handle the fault.
+ *
+ *  NOTE: There are problems with this approach:
+ *    1. we can't honor the sa_flags for the previous handler,
+ *    2. what if this thread is suspended just after calling signal(3)?
+ *       The sigNext variable will never be initialized!
+ */
+
+void ProtSetup(void)
+{
+  struct sigaction sa;
+  int result;
+
+  sa.sa_sigaction = sigHandle;
+  sigemptyset(&sa.sa_mask);
+  sa.sa_flags = SA_SIGINFO;
+
+  result = sigaction(PROT_SIGNAL, &sa, &sigNext);
+  AVER(result == 0);
+}
+
+/* C. COPYRIGHT AND LICENSE
+ *
+ * Copyright (C) 2001-2002 Ravenbrook Limited <http://www.ravenbrook.com/>.
+ * All rights reserved.  This is an open source license.  Contact
+ * Ravenbrook for commercial licensing options.
+ * 
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ * 
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 
+ * 3. Redistributions in any form must be accompanied by information on how
+ * to obtain complete source code for this software and any accompanying
+ * software that uses this software.  The source code must either be
+ * included in the distribution or be available for no more than the cost
+ * of distribution plus a nominal fee, and must be freely redistributable
+ * under reasonable conditions.  For an executable file, complete source
+ * code means the source code for all modules it contains. It does not
+ * include source code for modules or files that typically accompany the
+ * major components of the operating system on which the executable file
+ * runs.
+ * 
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
+ * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+ * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
+ * PURPOSE, OR NON-INFRINGEMENT, ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT HOLDERS AND CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
+ * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
+ * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
diff --git a/mps/code/ssixi6.c b/mps/code/ssixi6.c
index 6732f850b3b..6b425bed804 100644
--- a/mps/code/ssixi6.c
+++ b/mps/code/ssixi6.c
@@ -1,4 +1,4 @@
-/* ssixi6.c: UNIX/INTEL STACK SCANNING
+/* ssixi6.c: UNIX/x64 STACK SCANNING
  *
  * $Id$
  * Copyright (c) 2001 Ravenbrook Limited.  See end of file for license.
@@ -49,22 +49,21 @@ SRCID(ssixi6, "$Id$");
 
 Res StackScan(ScanState ss, Addr *stackBot)
 {
+  Addr calleeSaveRegs[6];
   Addr *stackTop;
   Res res;
 
-  ASMV("push %rbp");
-  ASMV("push %rbx");
-  ASMV("push %r12");
-  ASMV("push %r13");
-  ASMV("push %r14");
-  ASMV("push %r15");
-  ASMV("mov %%rsp, %0" : "=r" (stackTop) :);    /* stackTop = esp */
+  ASMV("mov %%rbp, %0" : "=m" (calleeSaveRegs[0]));
+  ASMV("mov %%rbx, %0" : "=m" (calleeSaveRegs[1]));
+  ASMV("mov %%r12, %0" : "=m" (calleeSaveRegs[2]));
+  ASMV("mov %%r13, %0" : "=m" (calleeSaveRegs[3]));
+  ASMV("mov %%r14, %0" : "=m" (calleeSaveRegs[4]));
+  ASMV("mov %%r15, %0" : "=m" (calleeSaveRegs[5]));
+  ASMV("mov %%rsp, %0" : "=r" (stackTop) :);    /* stackTop = rsp */
 
   AVER(AddrIsAligned((Addr)stackTop, sizeof(Addr)));  /* .assume.align */
   res = TraceScanArea(ss, stackTop, stackBot);
 
-  ASMV("add $48, %rsp");  /* pop 6 regs to restore the stack pointer */
-
   return res;
 }
 
diff --git a/mps/code/thli.c b/mps/code/thli.c
new file mode 100644
index 00000000000..a486e9ab9b6
--- /dev/null
+++ b/mps/code/thli.c
@@ -0,0 +1,350 @@
+/* thli.c: Threads Manager for LinuxThreads
+ *
+ *  $Id$
+ *  Copyright (c) 2001 Ravenbrook Limited.  See end of file for license.
+ *
+ * .purpose: This is a pthreads implementation of the threads manager.
+ * This implements <code/th.h>.
+ *
+ * .design: See <design/thread-manager/>.
+ *
+ * .thread.id: The thread id is used to identify the current thread.
+ *
+ * ASSUMPTIONS
+ *
+ * .error.resume: PThreadextResume is assumed to succeed unless the thread
+ * has been destroyed.
+ * .error.suspend: PThreadextSuspend is assumed to succeed unless the thread
+ * has been destroyed. In this case, the suspend context is set to NULL;
+ *
+ * .stack.full-descend:  assumes full descending stack.
+ * i.e. stack pointer points to the last allocated location;
+ * stack grows downwards.
+ *
+ * .stack.below-bottom: it's legal for the stack pointer to be at a
+ * higher address than the registered bottom of stack. This might
+ * happen if the stack of another thread doesn't contain any frames
+ * belonging to the client language. In this case, the stack should
+ * not be scanned.
+ *
+ * .stack.align: assume roots on the stack are always word-aligned,
+ * but don't assume that the stack pointer is necessarily
+ * word-aligned at the time of reading the context of another thread.
+ *
+ * .sp: The stack pointer in the context is uc_stack.ss_sp.
+ * .context.regroots: The root regs are
+ * assumed to be recorded in the context at pointer-aligned boundaries.
+ */
+
+#include "prmcix.h"
+#include "mpm.h"
+
+#if !defined(MPS_OS_LI)
+#error "Compiling thli when MPS_OS_LI is not defined."
+#endif
+
+#if !(defined(MPS_ARCH_I4) || defined(MPS_ARCH_I6))
+#error "Need to check assumptions for thli.c are true for this architecture"
+#endif
+
+#include <pthread.h>
+#include "pthrdext.h"
+
+SRCID(thli, "$Id$");
+
+
+/* ThreadStruct -- thread desriptor */
+
+typedef struct ThreadStruct {    /* PThreads thread structure */
+  Sig sig;                       /* <design/sig/> */
+  Serial serial;                 /* from arena->threadSerial */
+  Arena arena;                   /* owning arena */
+  RingStruct arenaRing;          /* threads attached to arena */
+  PThreadextStruct thrextStruct; /* PThreads extension */
+  pthread_t id;                  /* Pthread object of thread */
+  MutatorFaultContext mfc;       /* Context if thread is suspended */
+} ThreadStruct;
+
+
+/* ThreadCheck -- check a thread */
+
+Bool ThreadCheck(Thread thread)
+{
+  CHECKS(Thread, thread);
+  CHECKU(Arena, thread->arena);
+  CHECKL(thread->serial < thread->arena->threadSerial);
+  CHECKL(RingCheck(&thread->arenaRing));
+  CHECKD(PThreadext, &thread->thrextStruct);
+  return TRUE;
+}
+
+Bool ThreadCheckSimple(Thread thread)
+{
+  CHECKS(Thread, thread);
+  return TRUE;
+}
+
+
+/* ThreadRegister -- register a thread with an arena */
+
+Res ThreadRegister(Thread *threadReturn, Arena arena)
+{
+  Res res;
+  Thread thread;
+  void *p;
+
+  AVER(threadReturn != NULL);
+  AVERT(Arena, arena);
+
+  res = ControlAlloc(&p, arena, sizeof(ThreadStruct),
+                     /* withReservoirPermit */ FALSE);
+  if(res != ResOK)
+    return res;
+  thread = (Thread)p;
+
+  thread->id = pthread_self();
+
+  RingInit(&thread->arenaRing);
+
+  thread->sig = ThreadSig;
+  thread->serial = arena->threadSerial;
+  ++arena->threadSerial;
+  thread->arena = arena;
+  thread->mfc = NULL;
+
+  PThreadextInit(&thread->thrextStruct, thread->id);
+
+  AVERT(Thread, thread);
+
+  RingAppend(ArenaThreadRing(arena), &thread->arenaRing);
+
+  *threadReturn = thread;
+  return ResOK;
+}
+
+
+/* ThreadDeregister -- deregister a thread from an arena */
+
+void ThreadDeregister(Thread thread, Arena arena)
+{
+  AVERT(Thread, thread);
+  AVERT(Arena, arena);
+
+  RingRemove(&thread->arenaRing);
+
+  thread->sig = SigInvalid;
+
+  RingFinish(&thread->arenaRing);
+
+  PThreadextFinish(&thread->thrextStruct);
+
+  ControlFree(arena, thread, sizeof(ThreadStruct));
+}
+
+
+/*  mapThreadRing -- map over threads on ring calling a function on each one
+ *                   except the current thread
+ */
+
+static void mapThreadRing(Ring threadRing, void (*func)(Thread))
+{
+  Ring node, next;
+  pthread_t self;
+
+  AVERT(Ring, threadRing);
+
+  self = pthread_self();
+  RING_FOR(node, threadRing, next) {
+    Thread thread = RING_ELT(Thread, arenaRing, node);
+    AVERT(Thread, thread);
+    if(! pthread_equal(self, thread->id)) /* .thread.id */
+      (*func)(thread);
+  }
+}
+
+
+/* ThreadRingSuspend -- suspend all threads on a ring, expect the current one */
+
+
+static void threadSuspend(Thread thread)
+{
+  /* .error.suspend */
+  /* In the error case (PThreadextSuspend returning ResFAIL), we */
+  /* assume the thread has been destroyed. */
+  /* In which case we simply continue. */
+  Res res;
+  res = PThreadextSuspend(&thread->thrextStruct, &thread->mfc);
+  if(res != ResOK)
+    thread->mfc = NULL;
+}
+
+
+
+void ThreadRingSuspend(Ring threadRing)
+{
+  mapThreadRing(threadRing, threadSuspend);
+}
+
+
+/* ThreadRingResume -- resume all threads on a ring (expect the current one) */
+
+
+static void threadResume(Thread thread)
+{
+  /* .error.resume */
+  /* If the previous suspend failed (thread->mfc == NULL), */
+  /* or in the error case (PThreadextResume returning ResFAIL), */
+  /* assume the thread has been destroyed. */
+  /* In which case we simply continue. */
+  if(thread->mfc != NULL) {
+    (void)PThreadextResume(&thread->thrextStruct);
+    thread->mfc = NULL;
+  }
+}
+
+void ThreadRingResume(Ring threadRing)
+{
+  mapThreadRing(threadRing, threadResume);
+}
+
+
+/* ThreadRingThread -- return the thread at the given ring element */
+
+Thread ThreadRingThread(Ring threadRing)
+{
+  Thread thread;
+  AVERT(Ring, threadRing);
+  thread = RING_ELT(Thread, arenaRing, threadRing);
+  AVERT(Thread, thread);
+  return thread;
+}
+
+
+/* ThreadArena -- get the arena of a thread
+ *
+ * Must be thread-safe.  See <design/interface-c/#thread-safety>.
+ */
+
+Arena ThreadArena(Thread thread)
+{
+  /* Can't check thread as that would not be thread-safe. */
+  return thread->arena;
+}
+
+
+/* ThreadScan -- scan the state of a thread (stack and regs) */
+
+Res ThreadScan(ScanState ss, Thread thread, void *stackBot)
+{
+  pthread_t self;
+  Res res;
+
+  AVERT(Thread, thread);
+  self = pthread_self();
+  if(pthread_equal(self, thread->id)) {
+    /* scan this thread's stack */
+    res = StackScan(ss, stackBot);
+    if(res != ResOK)
+      return res;
+  } else {
+    MutatorFaultContext mfc;
+    Addr *stackBase, *stackLimit, stackPtr;
+    mcontext_t *mc;
+    mfc = thread->mfc;
+    if(mfc == NULL) {
+      /* .error.suspend */
+      /* We assume that the thread must have been destroyed. */
+      /* We ignore the situation by returning immediately. */
+      return ResOK;
+    }
+
+    stackPtr  = (Addr)mfc->ucontext->uc_stack.ss_sp;   /* .sp */
+    /* .stack.align */
+    stackBase  = (Addr *)AddrAlignUp(stackPtr, sizeof(Addr));
+    stackLimit = (Addr *)stackBot;
+    if (stackBase >= stackLimit)
+      return ResOK;    /* .stack.below-bottom */
+
+    /* scan stack inclusive of current sp and exclusive of
+     * stackBot (.stack.full-descend)
+     */
+    res = TraceScanAreaTagged(ss, stackBase, stackLimit);
+    if(res != ResOK)
+      return res;
+
+    /* (.context.regroots)
+     * This scans the root registers (.context.regroots).  It also
+     * unecessarily scans the rest of the context.  The optimisation
+     * to scan only relevent parts would be machine dependent.
+     */
+    mc = &mfc->ucontext->uc_mcontext;
+    res = TraceScanAreaTagged(ss, (Addr *)mc,
+           (Addr *)((char *)mc + sizeof(*mc)));
+    if(res != ResOK)
+      return res;
+  }
+
+  return ResOK;
+}
+
+
+/* ThreadDescribe -- describe a thread */
+
+Res ThreadDescribe(Thread thread, mps_lib_FILE *stream)
+{
+  Res res;
+
+  res = WriteF(stream,
+               "Thread $P ($U) {\n", (WriteFP)thread, (WriteFU)thread->serial,
+               "  arena $P ($U)\n",
+               (WriteFP)thread->arena, (WriteFU)thread->arena->serial,
+               "  id $U\n",          (WriteFU)thread->id,
+               "} Thread $P ($U)\n", (WriteFP)thread, (WriteFU)thread->serial,
+               NULL);
+  if(res != ResOK)
+    return res;
+
+  return ResOK;
+}
+
+
+/* C. COPYRIGHT AND LICENSE
+ *
+ * Copyright (C) 2001-2002 Ravenbrook Limited <http://www.ravenbrook.com/>.
+ * All rights reserved.  This is an open source license.  Contact
+ * Ravenbrook for commercial licensing options.
+ * 
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ * 
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 
+ * 3. Redistributions in any form must be accompanied by information on how
+ * to obtain complete source code for this software and any accompanying
+ * software that uses this software.  The source code must either be
+ * included in the distribution or be available for no more than the cost
+ * of distribution plus a nominal fee, and must be freely redistributable
+ * under reasonable conditions.  For an executable file, complete source
+ * code means the source code for all modules it contains. It does not
+ * include source code for modules or files that typically accompany the
+ * major components of the operating system on which the executable file
+ * runs.
+ * 
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
+ * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+ * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
+ * PURPOSE, OR NON-INFRINGEMENT, ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT HOLDERS AND CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
+ * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
+ * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */