3 files changed, 38 insertions, 19 deletions

diff --git a/src/sim/process.cc b/src/sim/process.cc
index 575627367..def42c0b2 100644
--- a/src/sim/process.cc
+++ b/src/sim/process.cc
@@ -472,6 +472,7 @@ Process::map(Addr vaddr, Addr paddr, int size, bool cacheable)
 LiveProcess::LiveProcess(LiveProcessParams *params, ObjectFile *_objFile)
     : Process(params), objFile(_objFile),
       argv(params->cmd), envp(params->env), cwd(params->cwd),
+      executable(params->executable),
       __uid(params->uid), __euid(params->euid),
       __gid(params->gid), __egid(params->egid),
       __pid(params->pid), __ppid(params->ppid),
@@ -528,11 +529,15 @@ LiveProcess::create(LiveProcessParams * params)
 {
     LiveProcess *process = NULL;
 
-    string executable =
-        params->executable == "" ? params->cmd[0] : params->executable;
-    ObjectFile *objFile = createObjectFile(executable);
+    // If not specified, set the executable parameter equal to the
+    // simulated system's zeroth command line parameter
+    if (params->executable == "") {
+        params->executable = params->cmd[0];
+    }
+
+    ObjectFile *objFile = createObjectFile(params->executable);
     if (objFile == NULL) {
-        fatal("Can't load object file %s", executable);
+        fatal("Can't load object file %s", params->executable);
     }
 
     if (objFile->isDynamic())
diff --git a/src/sim/process.hh b/src/sim/process.hh
index f509b81c7..43d1a4edc 100644
--- a/src/sim/process.hh
+++ b/src/sim/process.hh
@@ -238,6 +238,7 @@ class LiveProcess : public Process
     std::vector<std::string> argv;
     std::vector<std::string> envp;
     std::string cwd;
+    std::string executable;
 
     LiveProcess(LiveProcessParams *params, ObjectFile *objFile);
 
@@ -294,7 +295,7 @@ class LiveProcess : public Process
     inline uint64_t ppid() {return __ppid;}
 
     // provide program name for debug messages
-    virtual const char *progName() const { return argv[0].c_str(); }
+    virtual const char *progName() const { return executable.c_str(); }
 
     std::string
     fullPath(const std::string &filename)
diff --git a/src/sim/syscall_emul.cc b/src/sim/syscall_emul.cc
index f5b273202..3dda05da7 100644
--- a/src/sim/syscall_emul.cc
+++ b/src/sim/syscall_emul.cc
@@ -407,25 +407,38 @@ readlinkFunc(SyscallDesc *desc, int num, LiveProcess *p, ThreadContext *tc,
     if (path != "/proc/self/exe") {
         result = readlink(path.c_str(), (char *)buf.bufferPtr(), bufsiz);
     } else {
-        // readlink() will return the path of the binary given
-        // with the -c option, however it is possible that this
-        // will still result in incorrect behavior if one binary
-        // runs another, e.g., -c time -o "my_binary" where
-        // my_binary calls readlink(). this is a very unlikely case,
-        // so we issue a warning.
-        warn_once("readlink may yield unexpected results if multiple "
-                  "binaries are used\n");
-        if (strlen(p->progName()) > bufsiz) {
+        // Emulate readlink() called on '/proc/self/exe' should return the
+        // absolute path of the binary running in the simulated system (the
+        // LiveProcess' executable). It is possible that using this path in
+        // the simulated system will result in unexpected behavior if:
+        //  1) One binary runs another (e.g., -c time -o "my_binary"), and
+        //     called binary calls readlink().
+        //  2) The host's full path to the running benchmark changes from one
+        //     simulation to another. This can result in different simulated
+        //     performance since the simulated system will process the binary
+        //     path differently, even if the binary itself does not change.
+
+        // Get the absolute canonical path to the running application
+        char real_path[PATH_MAX];
+        char *check_real_path = realpath(p->progName(), real_path);
+        if (!check_real_path) {
+            fatal("readlink('/proc/self/exe') unable to resolve path to "
+                  "executable: %s", p->progName());
+        }
+        strncpy((char*)buf.bufferPtr(), real_path, bufsiz);
+        size_t real_path_len = strlen(real_path);
+        if (real_path_len > bufsiz) {
             // readlink will truncate the contents of the
             // path to ensure it is no more than bufsiz
-            strncpy((char*)buf.bufferPtr(), p->progName(), bufsiz);
             result = bufsiz;
         } else {
-            // return the program's working path rather
-            // than the one for the gem5 binary itself.
-            strcpy((char*)buf.bufferPtr(), p->progName());
-            result = strlen((char*)buf.bufferPtr());
+            result = real_path_len;
         }
+
+        // Issue a warning about potential unexpected results
+        warn_once("readlink() called on '/proc/self/exe' may yield unexpected "
+                  "results in various settings.\n      Returning '%s'\n",
+                  (char*)buf.bufferPtr());
     }
 
     buf.copyOut(tc->getMemProxy());