Restructuring of LiveProcess etc. to support multiple emulated OS syscall

interfaces, and specific support for Alpha Linux.  Split syscall emulation
functions into several groups, based on whether they depend on the specific
OS and/or architecture (and all combinations of above), including the use of
template functions to support syscalls with slightly different constants
or interface structs.

arch/alpha/alpha_tru64_process.cc:
    Incorporate full Tru64 object definition here, including structure and constant definitions.
    This way we can wrap all of the functions inside the object, and not worry about namespace
    conflicts because no one outside this file will ever see it.
base/loader/aout_object.cc:
base/loader/aout_object.hh:
base/loader/ecoff_object.cc:
base/loader/ecoff_object.hh:
base/loader/elf_object.cc:
base/loader/elf_object.hh:
base/loader/object_file.cc:
base/loader/object_file.hh:
    Add enums to ObjectFile to indicate the object's architecture and operating system.
cpu/exec_context.cc:
    prog.hh is now process.hh
cpu/exec_context.hh:
    prog.hh is now process.hh
    move architecture-specific syscall arg accessors into ExecContext
cpu/simple_cpu/simple_cpu.cc:
    No need to include prog.hh (which has been renamed)
sim/process.cc:
sim/process.hh:
    LiveProcess is now effectively an abstract base class.
    New LiveProcess::create() function takes an object file and dynamically picks the
    appropriate subclass of LiveProcess to handle the syscall interface that file expects
    (currently Tru64 or Linux).

--HG--
rename : arch/alpha/fake_syscall.cc => arch/alpha/alpha_tru64_process.cc
rename : sim/prog.cc => sim/process.cc
rename : sim/prog.hh => sim/process.hh
extra : convert_revision : 4a03ca7d94a34177cb672931f8aae83a6bad179a

4 files changed, 733 insertions, 27 deletions

diff --git a/sim/prog.cc b/sim/process.cc
index fca4b4505..bb4333896 100644
--- a/sim/prog.cc
+++ b/sim/process.cc
@@ -42,9 +42,14 @@
 #include "mem/functional_mem/main_memory.hh"
 #include "sim/builder.hh"
 #include "sim/fake_syscall.hh"
-#include "sim/prog.hh"
+#include "sim/process.hh"
 #include "sim/sim_stats.hh"
 
+#ifdef TARGET_ALPHA
+#include "arch/alpha/alpha_tru64_process.hh"
+#include "arch/alpha/alpha_linux_process.hh"
+#endif
+
 using namespace std;
 
 //
@@ -53,13 +58,9 @@ using namespace std;
 // mode when we do have an OS
 //
 #ifdef FULL_SYSTEM
-#error "prog.cc not compatible with FULL_SYSTEM"
+#error "process.cc not compatible with FULL_SYSTEM"
 #endif
 
-// max allowable number of processes: should be no real cost to
-// cranking this up if necessary
-const int MAX_PROCESSES = 8;
-
 // current number of allocated processes
 int num_processes = 0;
 
@@ -242,16 +243,12 @@ copyStringArray(vector<string> &strings, Addr array_ptr, Addr data_ptr,
     memory->access(Write, array_ptr, &data_ptr, sizeof(Addr));
 }
 
-LiveProcess::LiveProcess(const string &name,
+LiveProcess::LiveProcess(const string &name, ObjectFile *objFile,
                          int stdin_fd, int stdout_fd, int stderr_fd,
                          vector<string> &argv, vector<string> &envp)
     : Process(name, stdin_fd, stdout_fd, stderr_fd)
 {
     prog_fname = argv[0];
-    ObjectFile *objFile = createObjectFile(prog_fname);
-    if (objFile == NULL) {
-        fatal("Can't load object file %s", prog_fname);
-    }
 
     prog_entry = objFile->entryPoint();
     text_base = objFile->textBase();
@@ -267,6 +264,10 @@ LiveProcess::LiveProcess(const string &name,
     // code should get moved to some architecture-specific spot.
     stack_base = text_base - (409600+4096);
 
+    // Set up region for mmaps.  Tru64 seems to start just above 0 and
+    // grow up from there.
+    mmap_base = 0x10000;
+
     // Set pointer for next thread stack.  Reserve 8M for main stack.
     next_thread_stack_base = stack_base - (8 * 1024 * 1024);
 
@@ -316,12 +317,45 @@ LiveProcess::LiveProcess(const string &name,
 }
 
 
-void
-LiveProcess::syscall(ExecContext *xc)
+LiveProcess *
+LiveProcess::create(const string &name,
+                    int stdin_fd, int stdout_fd, int stderr_fd,
+                    vector<string> &argv, vector<string> &envp)
 {
-    num_syscalls++;
+    LiveProcess *process = NULL;
+    ObjectFile *objFile = createObjectFile(argv[0]);
+    if (objFile == NULL) {
+        fatal("Can't load object file %s", argv[0]);
+    }
+
+    // check object type & set up syscall emulation pointer
+    if (objFile->getArch() == ObjectFile::Alpha) {
+        switch (objFile->getOpSys()) {
+          case ObjectFile::Tru64:
+            process = new AlphaTru64Process(name, objFile,
+                                            stdin_fd, stdout_fd, stderr_fd,
+                                            argv, envp);
+            break;
+
+          case ObjectFile::Linux:
+            process = new AlphaLinuxProcess(name, objFile,
+                                            stdin_fd, stdout_fd, stderr_fd,
+                                            argv, envp);
+            break;
+
+          default:
+            fatal("Unknown/unsupported operating system.");
+        }
+    } else {
+        fatal("Unknown object file architecture.");
+    }
+
+    delete objFile;
+
+    if (process == NULL)
+        fatal("Unknown error creating process object.");
 
-    fake_syscall(this, xc);
+    return process;
 }
 
 
@@ -357,10 +391,10 @@ CREATE_SIM_OBJECT(LiveProcess)
 
     //  We do this with "temp" because of the bogus compiler warning
     //  you get with g++ 2.95 -O if you just "return new LiveProcess(..."
-    LiveProcess *temp = new LiveProcess(getInstanceName(),
-                                        stdin_fd, stdout_fd, stderr_fd,
-                                        cmd,
-                                        env.isValid() ? env : null_vec);
+    LiveProcess *temp = LiveProcess::create(getInstanceName(),
+                                            stdin_fd, stdout_fd, stderr_fd,
+                                            cmd,
+                                            env.isValid() ? env : null_vec);
 
     return temp;
 }
diff --git a/sim/prog.hh b/sim/process.hh
index e93dd684c..5df5736ff 100644
--- a/sim/prog.hh
+++ b/sim/process.hh
@@ -26,8 +26,8 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-#ifndef __PROG_HH__
-#define __PROG_HH__
+#ifndef __PROCESS_HH__
+#define __PROCESS_HH__
 
 //
 // The purpose of this code is to fake the loader & syscall mechanism
@@ -89,10 +89,12 @@ class Process : public SimObject
     unsigned stack_size;	// initial stack size
     Addr stack_min;		// lowest address accessed on the stack
 
-
     // addr to use for next stack region (for multithreaded apps)
     Addr next_thread_stack_base;
 
+    // Base of region for mmaps (when user doesn't specify an address).
+    Addr mmap_base;
+
     std::string prog_fname;	// file name
     Addr prog_entry;		// entry point (initial PC)
 
@@ -165,18 +167,26 @@ class Process : public SimObject
 //
 // "Live" process with system calls redirected to host system
 //
-class MainMemory;
+class ObjectFile;
 class LiveProcess : public Process
 {
-  public:
-    LiveProcess(const std::string &name,
+  protected:
+    LiveProcess(const std::string &name, ObjectFile *objFile,
                 int stdin_fd, int stdout_fd, int stderr_fd,
                 std::vector<std::string> &argv,
                 std::vector<std::string> &envp);
 
-    virtual void syscall(ExecContext *xc);
+  public:
+    // this function is used to create the LiveProcess object, since
+    // we can't tell which subclass of LiveProcess to use until we
+    // open and look at the object file.
+    static LiveProcess *create(const std::string &name,
+                               int stdin_fd, int stdout_fd, int stderr_fd,
+                               std::vector<std::string> &argv,
+                               std::vector<std::string> &envp);
 };
 
+
 #endif // !FULL_SYSTEM
 
-#endif // __PROG_HH__
+#endif // __PROCESS_HH__
diff --git a/sim/syscall_emul.cc b/sim/syscall_emul.cc
new file mode 100644
index 000000000..0e4e78612
--- /dev/null
+++ b/sim/syscall_emul.cc
@@ -0,0 +1,197 @@
+/*
+ * Copyright (c) 2003 The Regents of The University of Michigan
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met: redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer;
+ * 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;
+ * neither the name of the copyright holders nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * 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 AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR 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.
+ */
+
+#include <unistd.h>
+
+#include <string>
+#include <iostream>
+
+#include "sim/syscall_emul.hh"
+#include "base/trace.hh"
+#include "cpu/exec_context.hh"
+#include "cpu/base_cpu.hh"
+#include "sim/process.hh"
+
+#include "sim/sim_events.hh"
+
+using namespace std;
+
+void
+SyscallDesc::doSyscall(int callnum, Process *process, ExecContext *xc)
+{
+    DPRINTFR(SyscallVerbose, "%s: syscall %s called\n",
+             xc->cpu->name(), name);
+
+    int retval = (*funcPtr)(this, callnum, process, xc);
+
+    DPRINTFR(SyscallVerbose, "%s: syscall %s returns %d\n",
+             xc->cpu->name(), name, retval);
+
+    if (!((flags & SyscallDesc::SuppressReturnValue) && retval == 0))
+        xc->setSyscallReturn(retval);
+}
+
+
+//
+// Handler for unimplemented syscalls that we haven't thought about.
+//
+int
+unimplementedFunc(SyscallDesc *desc, int callnum, Process *process,
+                  ExecContext *xc)
+{
+    cerr << "Error: syscall " << desc->name
+         << " (#" << callnum << ") unimplemented.";
+    cerr << "  Args: " << xc->getSyscallArg(0) << ", " << xc->getSyscallArg(1)
+         << ", ..." << endl;
+
+    abort();
+}
+
+
+//
+// Handler for unimplemented syscalls that we never intend to
+// implement (signal handling, etc.) and should not affect the correct
+// behavior of the program.  Print a warning only if the appropriate
+// trace flag is enabled.  Return success to the target program.
+//
+int
+ignoreFunc(SyscallDesc *desc, int callnum, Process *process,
+           ExecContext *xc)
+{
+    DCOUT(SyscallWarnings) << "Warning: ignoring syscall " << desc->name
+                           << "(" << xc->getSyscallArg(0)
+                           << ", " << xc->getSyscallArg(1)
+                           << ", ...)" << endl;
+
+    return 0;
+}
+
+
+int
+exitFunc(SyscallDesc *desc, int callnum, Process *process,
+         ExecContext *xc)
+{
+    new SimExitEvent("syscall caused exit", xc->getSyscallArg(0) & 0xff);
+
+    return 1;
+}
+
+
+int
+getpagesizeFunc(SyscallDesc *desc, int num, Process *p, ExecContext *xc)
+{
+    return VMPageSize;
+}
+
+
+int
+obreakFunc(SyscallDesc *desc, int num, Process *p, ExecContext *xc)
+{
+    // change brk addr to first arg
+    p->brk_point = xc->getSyscallArg(0);
+    return p->brk_point;
+}
+
+
+int
+closeFunc(SyscallDesc *desc, int num, Process *p, ExecContext *xc)
+{
+    int fd = p->sim_fd(xc->getSyscallArg(0));
+    return close(fd);
+}
+
+
+int
+readFunc(SyscallDesc *desc, int num, Process *p, ExecContext *xc)
+{
+    int fd = p->sim_fd(xc->getSyscallArg(0));
+    int nbytes = xc->getSyscallArg(2);
+    BufferArg bufArg(xc->getSyscallArg(1), nbytes);
+
+    int bytes_read = read(fd, bufArg.bufferPtr(), nbytes);
+
+    if (bytes_read != -1)
+        bufArg.copyOut(xc->mem);
+
+    return bytes_read;
+}
+
+int
+writeFunc(SyscallDesc *desc, int num, Process *p, ExecContext *xc)
+{
+    int fd = p->sim_fd(xc->getSyscallArg(0));
+    int nbytes = xc->getSyscallArg(2);
+    BufferArg bufArg(xc->getSyscallArg(1), nbytes);
+
+    bufArg.copyIn(xc->mem);
+
+    int bytes_written = write(fd, bufArg.bufferPtr(), nbytes);
+
+    fsync(fd);
+
+    return bytes_written;
+}
+
+
+int
+lseekFunc(SyscallDesc *desc, int num, Process *p, ExecContext *xc)
+{
+    int fd = p->sim_fd(xc->getSyscallArg(0));
+    uint64_t offs = xc->getSyscallArg(1);
+    int whence = xc->getSyscallArg(2);
+
+    off_t result = lseek(fd, offs, whence);
+
+    return (result == (off_t)-1) ? -errno : result;
+}
+
+
+int
+munmapFunc(SyscallDesc *desc, int num, Process *p, ExecContext *xc)
+{
+    // given that we don't really implement mmap, munmap is really easy
+    return 0;
+}
+
+
+const char *hostname = "m5.eecs.umich.edu";
+
+int
+gethostnameFunc(SyscallDesc *desc, int num, Process *p, ExecContext *xc)
+{
+    int name_len = xc->getSyscallArg(1);
+    BufferArg name(xc->getSyscallArg(0), name_len);
+
+    strncpy((char *)name.bufferPtr(), hostname, name_len);
+
+    name.copyOut(xc->mem);
+
+    return 0;
+}
+
+
diff --git a/sim/syscall_emul.hh b/sim/syscall_emul.hh
new file mode 100644
index 000000000..a02b4a608
--- /dev/null
+++ b/sim/syscall_emul.hh
@@ -0,0 +1,465 @@
+/*
+ * Copyright (c) 2003 The Regents of The University of Michigan
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met: redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer;
+ * 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;
+ * neither the name of the copyright holders nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * 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 AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR 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.
+ */
+
+#ifndef __SYSCALL_EMUL_HH__
+#define __SYSCALL_EMUL_HH__
+
+///
+/// @file syscall_emul.hh
+///
+/// This file defines objects used to emulate syscalls from the target
+/// application on the host machine.
+
+#include <string>
+
+#include "base/intmath.hh"	// for RoundUp
+#include "targetarch/isa_traits.hh"	// for Addr
+#include "mem/functional_mem/functional_memory.hh"
+
+class Process;
+class ExecContext;
+
+///
+/// System call descriptor.
+///
+class SyscallDesc {
+
+  public:
+
+    typedef int (*FuncPtr)(SyscallDesc *, int num,
+                           Process *, ExecContext *);
+
+    const char *name;	//!< Syscall name (e.g., "open").
+    FuncPtr funcPtr;	//!< Pointer to emulation function.
+    int flags;		//!< Flags (see Flags enum).
+
+
+    /// Flag values for controlling syscall behavior.
+    enum Flags {
+        /// Don't set return regs according to funcPtr return value.
+        /// Used for syscalls with non-standard return conventions
+        /// that explicitly set the ExecContext regs (e.g.,
+        /// sigreturn).
+        SuppressReturnValue = 1
+    };
+
+    /// Constructor.
+    SyscallDesc(const char *_name, FuncPtr _funcPtr, int _flags = 0)
+        : name(_name), funcPtr(_funcPtr), flags(_flags)
+    {
+    }
+
+    /// Emulate the syscall.  Public interface for calling through funcPtr.
+    void doSyscall(int callnum, Process *proc, ExecContext *xc);
+};
+
+
+class BaseBufferArg {
+
+  public:
+
+    BaseBufferArg(Addr _addr, int _size) : addr(_addr), size(_size)
+    {
+        bufPtr = new uint8_t[size];
+        // clear out buffer: in case we only partially populate this,
+        // and then do a copyOut(), we want to make sure we don't
+        // introduce any random junk into the simulated address space
+        memset(bufPtr, 0, size);
+    }
+
+    virtual ~BaseBufferArg() { delete [] bufPtr; }
+
+    //
+    // copy data into simulator space (read from target memory)
+    //
+    virtual bool copyIn(FunctionalMemory *mem)
+    {
+        mem->access(Read, addr, bufPtr, size);
+        return true;	// no EFAULT detection for now
+    }
+
+    //
+    // copy data out of simulator space (write to target memory)
+    //
+    virtual bool copyOut(FunctionalMemory *mem)
+    {
+        mem->access(Write, addr, bufPtr, size);
+        return true;	// no EFAULT detection for now
+    }
+
+  protected:
+    Addr addr;
+    int size;
+    uint8_t *bufPtr;
+};
+
+
+class BufferArg : public BaseBufferArg
+{
+  public:
+    BufferArg(Addr _addr, int _size) : BaseBufferArg(_addr, _size) { }
+    void *bufferPtr()	{ return bufPtr; }
+};
+
+template <class T>
+class TypedBufferArg : public BaseBufferArg
+{
+  public:
+    // user can optionally specify a specific number of bytes to
+    // allocate to deal with those structs that have variable-size
+    // arrays at the end
+    TypedBufferArg(Addr _addr, int _size = sizeof(T))
+        : BaseBufferArg(_addr, _size)
+    { }
+
+    // type case
+    operator T*() { return (T *)bufPtr; }
+
+    // dereference operators
+    T& operator*()	 { return *((T *)bufPtr); }
+    T* operator->()	 { return (T *)bufPtr; }
+    T& operator[](int i) { return ((T *)bufPtr)[i]; }
+};
+
+//////////////////////////////////////////////////////////////////////
+//
+// The following emulation functions are generic enough that they
+// don't need to be recompiled for different emulated OS's.  They are
+// defined in sim/syscall_emul.cc.
+//
+//////////////////////////////////////////////////////////////////////
+
+
+int unimplementedFunc(SyscallDesc *desc, int num, Process *p, ExecContext *xc);
+int ignoreFunc(SyscallDesc *desc, int num, Process *p, ExecContext *xc);
+
+int exitFunc(SyscallDesc *desc, int num, Process *p, ExecContext *xc);
+int getpagesizeFunc(SyscallDesc *desc, int num, Process *p, ExecContext *xc);
+int obreakFunc(SyscallDesc *desc, int num, Process *p, ExecContext *xc);
+int closeFunc(SyscallDesc *desc, int num, Process *p, ExecContext *xc);
+int readFunc(SyscallDesc *desc, int num, Process *p, ExecContext *xc);
+int writeFunc(SyscallDesc *desc, int num, Process *p, ExecContext *xc);
+int lseekFunc(SyscallDesc *desc, int num, Process *p, ExecContext *xc);
+int munmapFunc(SyscallDesc *desc, int num, Process *p, ExecContext *xc);
+int gethostnameFunc(SyscallDesc *desc, int num, Process *p, ExecContext *xc);
+
+//////////////////////////////////////////////////////////////////////
+//
+// The following emulation functions are generic, but need to be
+// templated to account for differences in types, constants, etc.
+//
+//////////////////////////////////////////////////////////////////////
+
+template <class OS>
+int
+ioctlFunc(SyscallDesc *desc, int callnum, Process *process,
+          ExecContext *xc)
+{
+    int fd = xc->getSyscallArg(0);
+    unsigned req = xc->getSyscallArg(1);
+
+    // DPRINTFR(SyscallVerbose, "ioctl(%d, 0x%x, ...)\n", fd, req);
+
+    if (fd < 0 || process->sim_fd(fd) < 0) {
+        // doesn't map to any simulator fd: not a valid target fd
+        return -EBADF;
+    }
+
+    switch (req) {
+      case OS::TIOCISATTY:
+      case OS::TIOCGETP:
+      case OS::TIOCSETP:
+      case OS::TIOCSETN:
+      case OS::TIOCSETC:
+      case OS::TIOCGETC:
+        return -ENOTTY;
+
+      default:
+        fatal("Unsupported ioctl call: ioctl(%d, 0x%x, ...)\n", fd, req);
+    }
+}
+
+struct OpenFlagTransTable {
+    int tgtFlag;
+    int hostFlag;
+};
+
+
+template <class OS>
+int
+openFunc(SyscallDesc *desc, int callnum, Process *process,
+         ExecContext *xc)
+{
+    std::string path;
+
+    if (xc->mem->readString(path, xc->getSyscallArg(0)) != No_Fault)
+        return -EFAULT;
+
+    if (path == "/dev/sysdev0") {
+        // This is a memory-mapped high-resolution timer device on Alpha.
+        // We don't support it, so just punt.
+        DCOUT(SyscallWarnings) << "Ignoring open(" << path << ", ...)" << endl;
+        return -ENOENT;
+    }
+
+    int tgtFlags = xc->getSyscallArg(1);
+    int mode = xc->getSyscallArg(2);
+    int hostFlags = 0;
+
+    // translate open flags
+    for (int i = 0; i < OS::NUM_OPEN_FLAGS; i++) {
+        if (tgtFlags & OS::openFlagTable[i].tgtFlag) {
+            tgtFlags &= ~OS::openFlagTable[i].tgtFlag;
+            hostFlags |= OS::openFlagTable[i].hostFlag;
+        }
+    }
+
+    // any target flags left?
+    if (tgtFlags != 0)
+        cerr << "Syscall: open: cannot decode flags: " <<  tgtFlags << endl;
+
+#ifdef __CYGWIN32__
+    hostFlags |= O_BINARY;
+#endif
+
+    // open the file
+    int fd = open(path.c_str(), hostFlags, mode);
+
+    return (fd == -1) ? -errno : process->open_fd(fd);
+}
+
+
+template <class OS>
+int
+statFunc(SyscallDesc *desc, int callnum, Process *process,
+         ExecContext *xc)
+{
+    std::string path;
+
+    if (xc->mem->readString(path, xc->getSyscallArg(0)) != No_Fault)
+        return -EFAULT;
+
+    struct stat hostBuf;
+    int result = stat(path.c_str(), &hostBuf);
+
+    if (result < 0)
+        return -errno;
+
+    OS::copyOutStatBuf(xc->mem, xc->getSyscallArg(1), &hostBuf);
+
+    return 0;
+}
+
+
+template <class OS>
+int
+lstatFunc(SyscallDesc *desc, int callnum, Process *process,
+          ExecContext *xc)
+{
+    std::string path;
+
+    if (xc->mem->readString(path, xc->getSyscallArg(0)) != No_Fault)
+        return -EFAULT;
+
+    struct stat hostBuf;
+    int result = lstat(path.c_str(), &hostBuf);
+
+    if (result < 0)
+        return -errno;
+
+    OS::copyOutStatBuf(xc->mem, xc->getSyscallArg(1), &hostBuf);
+
+    return 0;
+}
+
+template <class OS>
+int
+fstatFunc(SyscallDesc *desc, int callnum, Process *process,
+          ExecContext *xc)
+{
+    int fd = process->sim_fd(xc->getSyscallArg(0));
+
+    // DPRINTFR(SyscallVerbose, "fstat(%d, ...)\n", fd);
+
+    if (fd < 0)
+        return -EBADF;
+
+    struct stat hostBuf;
+    int result = fstat(fd, &hostBuf);
+
+    if (result < 0)
+        return -errno;
+
+    OS::copyOutStatBuf(xc->mem, xc->getSyscallArg(1), &hostBuf);
+
+    return 0;
+}
+
+
+//
+// We don't really handle mmap().  If the target is mmaping an
+// anonymous region or /dev/zero, we can get away with doing basically
+// nothing (since memory is initialized to zero and the simulator
+// doesn't really check addresses anyway).  Always print a warning,
+// since this could be seriously broken if we're not mapping
+// /dev/zero.
+//
+// Someday we should explicitly check for /dev/zero in open, flag the
+// file descriptor, and fail (or implement!) a non-anonymous mmap to
+// anything else.
+//
+template <class OS>
+int
+mmapFunc(SyscallDesc *desc, int num, Process *p, ExecContext *xc)
+{
+    Addr start = xc->getSyscallArg(0);
+    uint64_t length = xc->getSyscallArg(1);
+    // int prot = xc->getSyscallArg(2);
+    int flags = xc->getSyscallArg(3);
+    int fd = p->sim_fd(xc->getSyscallArg(4));
+    // int offset = xc->getSyscallArg(5);
+
+    if (start == 0) {
+        // user didn't give an address... pick one from our "mmap region"
+        start = p->mmap_base;
+        p->mmap_base += RoundUp<Addr>(length, VMPageSize);
+    }
+
+    if (!(flags & OS::TGT_MAP_ANONYMOUS)) {
+        DPRINTF(SyscallWarnings, "Warning: allowing mmap of file @ fd %d.  "
+                "This will break if not /dev/zero.", fd);
+    }
+
+    return start;
+}
+
+
+template <class OS>
+int
+getrlimitFunc(SyscallDesc *desc, int callnum, Process *process,
+              ExecContext *xc)
+{
+    unsigned resource = xc->getSyscallArg(0);
+    TypedBufferArg<typename OS::rlimit> rlp(xc->getSyscallArg(1));
+
+    switch (resource) {
+      case OS::RLIMIT_STACK:
+        // max stack size in bytes: make up a number (2MB for now)
+        rlp->rlim_cur = rlp->rlim_max = 8 * 1024 * 1024;
+        break;
+
+      default:
+        cerr << "getrlimitFunc: unimplemented resource " << resource << endl;
+        abort();
+        break;
+    }
+
+    rlp.copyOut(xc->mem);
+    return 0;
+}
+
+// 1M usecs in 1 sec, for readability
+const int one_million = 1000000;
+
+// seconds since the epoch (1/1/1970)... about a billion, by my reckoning
+const unsigned seconds_since_epoch = 1000000000;
+
+//
+// helper function: populate struct timeval with approximation of
+// current elapsed time
+//
+template <class T1, class T2>
+void
+getElapsedTime(T1 &sec, T2 &usec)
+{
+    int cycles_per_usec = ticksPerSecond / one_million;
+
+    int elapsed_usecs = curTick / cycles_per_usec;
+    sec = elapsed_usecs / one_million;
+    usec = elapsed_usecs % one_million;
+}
+
+
+template <class OS>
+int
+gettimeofdayFunc(SyscallDesc *desc, int callnum, Process *process,
+                 ExecContext *xc)
+{
+    TypedBufferArg<typename OS::timeval> tp(xc->getSyscallArg(0));
+
+    getElapsedTime(tp->tv_sec, tp->tv_usec);
+    tp->tv_sec += seconds_since_epoch;
+
+    tp.copyOut(xc->mem);
+
+    return 0;
+}
+
+
+template <class OS>
+int
+getrusageFunc(SyscallDesc *desc, int callnum, Process *process,
+              ExecContext *xc)
+{
+    int who = xc->getSyscallArg(0);	// THREAD, SELF, or CHILDREN
+    TypedBufferArg<typename OS::rusage> rup(xc->getSyscallArg(1));
+
+    if (who != OS::RUSAGE_SELF) {
+        // don't really handle THREAD or CHILDREN, but just warn and
+        // plow ahead
+        DCOUT(SyscallWarnings)
+            << "Warning: getrusage() only supports RUSAGE_SELF."
+            << "  Parameter " << who << " ignored." << endl;
+    }
+
+    getElapsedTime(rup->ru_utime.tv_sec, rup->ru_utime.tv_usec);
+    rup->ru_stime.tv_sec = 0;
+    rup->ru_stime.tv_usec = 0;
+    rup->ru_maxrss = 0;
+    rup->ru_ixrss = 0;
+    rup->ru_idrss = 0;
+    rup->ru_isrss = 0;
+    rup->ru_minflt = 0;
+    rup->ru_majflt = 0;
+    rup->ru_nswap = 0;
+    rup->ru_inblock = 0;
+    rup->ru_oublock = 0;
+    rup->ru_msgsnd = 0;
+    rup->ru_msgrcv = 0;
+    rup->ru_nsignals = 0;
+    rup->ru_nvcsw = 0;
+    rup->ru_nivcsw = 0;
+
+    rup.copyOut(xc->mem);
+
+    return 0;
+}
+
+
+
+#endif // __SYSCALL_EMUL_HH__