syscall_emul: [patch 14/22] adds identifier system calls

This changeset add fields to the process object and adds the following
three system calls: setpgid, gettid, getpid.

src/sim/Process.py

@@ -47,7 +47,8 @@ class Process(SimObject):
     gid = Param.Int(100, 'group id')
     egid = Param.Int(100, 'effective group id')
     pid = Param.Int(100, 'process id')
-    ppid = Param.Int(99, 'parent process id')
+    ppid = Param.Int(0, 'parent process id')
+    pgid = Param.Int(100, 'process group id')
 
     executable = Param.String('', "executable (overrides cmd[0] if set)")
     cmd = VectorParam.String("command line (executable plus arguments)")

src/sim/process.cc

@@ -112,11 +112,18 @@ Process::Process(ProcessParams * params, ObjectFile * obj_file)
       _uid(params->uid), _euid(params->euid),
       _gid(params->gid), _egid(params->egid),
       _pid(params->pid), _ppid(params->ppid),
-      drivers(params->drivers),
+      _pgid(params->pgid), drivers(params->drivers),
       fds(make_shared<FDArray>(params->input, params->output, params->errout))
 {
     mmap_end = 0;
 
+    if (_pid >= System::maxPID)
+        fatal("_pid is too large: %d", _pid);
+
+    auto ret_pair = system->PIDs.emplace(_pid);
+    if (!ret_pair.second)
+        fatal("_pid %d is already used", _pid);
+
     // load up symbols, if any... these may be used for debugging or
     // profiling.
     if (!debugSymbolTable) {

src/sim/process.hh

@@ -95,6 +95,9 @@ class Process : public SimObject
     inline uint64_t egid() { return _egid; }
     inline uint64_t pid() { return _pid; }
     inline uint64_t ppid() { return _ppid; }
+    inline uint64_t pgid() { return _pgid; }
+    inline uint64_t tgid() { return _tgid; }
+    inline void setpgid(uint64_t pgid) { _pgid = pgid; }
 
     const char *progName() const { return executable.c_str(); }
     std::string fullPath(const std::string &filename);
@@ -199,6 +202,8 @@ class Process : public SimObject
     // pid of the process and it's parent
     uint64_t _pid;
     uint64_t _ppid;
+    uint64_t _pgid;
+    uint64_t _tgid;
 
     // Emulated drivers available to this process
     std::vector<EmulatedDriver *> drivers;

src/sim/syscall_emul.cc

@@ -729,6 +729,41 @@ pipePseudoFunc(SyscallDesc *desc, int callnum, Process *process,
     return sim_fds[0];
 }
 
+SyscallReturn
+setpgidFunc(SyscallDesc *desc, int callnum, Process *process,
+            ThreadContext *tc)
+{
+    int index = 0;
+    int pid = process->getSyscallArg(tc, index);
+    int pgid = process->getSyscallArg(tc, index);
+
+    if (pgid < 0)
+        return -EINVAL;
+
+    if (pid == 0) {
+        process->setpgid(process->pid());
+        return 0;
+    }
+
+    Process *matched_ph = NULL;
+    System *sysh = tc->getSystemPtr();
+
+    // Retrieves process pointer from active/suspended thread contexts.
+    for (int i = 0; i < sysh->numContexts(); i++) {
+        if (sysh->threadContexts[i]->status() != ThreadContext::Halted) {
+            Process *temp_h = sysh->threadContexts[i]->getProcessPtr();
+            Process *walk_ph = (Process*)temp_h;
+
+            if (walk_ph && walk_ph->pid() == process->pid())
+                matched_ph = walk_ph;
+        }
+    }
+
+    assert(matched_ph != NULL);
+    matched_ph->setpgid((pgid == 0) ? matched_ph->pid() : pgid);
+
+    return 0;
+}
 
 SyscallReturn
 getpidPseudoFunc(SyscallDesc *desc, int callnum, Process *process,
@@ -780,11 +815,13 @@ SyscallReturn
 getpidFunc(SyscallDesc *desc, int callnum, Process *process,
            ThreadContext *tc)
 {
-    // Make up a PID.  There's no interprocess communication in
-    // fake_syscall mode, so there's no way for a process to know it's
-    // not getting a unique value.
+    return process->tgid();
+}
 
-    tc->setIntReg(SyscallPseudoReturnReg, process->ppid()); //PID
+SyscallReturn
+gettidFunc(SyscallDesc *desc, int callnum, Process *process,
+           ThreadContext *tc)
+{
     return process->pid();
 }
 

src/sim/syscall_emul.hh

@@ -216,11 +216,17 @@ SyscallReturn ftruncate64Func(SyscallDesc *desc, int num,
 SyscallReturn umaskFunc(SyscallDesc *desc, int num,
                         Process *p, ThreadContext *tc);
 
+/// Target gettid() handler.
+SyscallReturn gettidFunc(SyscallDesc *desc, int num,
+                         Process *p, ThreadContext *tc);
 
 /// Target chown() handler.
 SyscallReturn chownFunc(SyscallDesc *desc, int num,
                         Process *p, ThreadContext *tc);
 
+/// Target setpgid() handler.
+SyscallReturn setpgidFunc(SyscallDesc *desc, int num,
+                          Process *p, ThreadContext *tc);
 
 /// Target fchown() handler.
 SyscallReturn fchownFunc(SyscallDesc *desc, int num,

src/sim/system.hh

@@ -551,6 +551,11 @@ class System : public MemObject
     // For futex system call
     std::map<uint64_t, std::list<ThreadContext *> * > futexMap;
 
+    static const int maxPID = 32768;
+
+    /** Process set to track which PIDs have already been allocated */
+    std::set<int> PIDs;
+
   protected:
 
     /**