[Openmp-commits] [PATCH] D73657: [OPENMP] Load plugins from same directory as the libomptarget.so and quick fail mechanism for offloading plugins

[Greg Rodgers via Phabricator via Openmp-commits]

gregrodgers created this revision.
gregrodgers added a project: OpenMP.
Herald added a subscriber: guansong.

This patch  loads plugins from the same directory as libomptarget.so is found.  This avoids the need to set LD_LIBRARY_PATH to find plugins whose relative names are hardcoded in this source file.

This patch also provides a quick fail mechanism to avoid doing a dlopen for a platform that is not operational.

This patch also adds the name for the amdgcn plugin.


https://reviews.llvm.org/D73657

Files:
  openmp/libomptarget/src/rtl.cpp


Index: openmp/libomptarget/src/rtl.cpp
===================================================================
--- openmp/libomptarget/src/rtl.cpp
+++ openmp/libomptarget/src/rtl.cpp
@@ -20,14 +20,28 @@
 #include <dlfcn.h>
 #include <mutex>
 #include <string>
+#include <sys/stat.h>
 
 // List of all plugins that can support offloading.
 static const char *RTLNames[] = {
     /* PowerPC target */ "libomptarget.rtl.ppc64.so",
     /* x86_64 target  */ "libomptarget.rtl.x86_64.so",
     /* CUDA target    */ "libomptarget.rtl.cuda.so",
+    /* HSA target     */ "libomptarget.rtl.hsa.so",
     /* AArch64 target */ "libomptarget.rtl.aarch64.so"};
 
+// Define the platform quick check files.
+// At least one must be found to attempt to load plugin for that platform.
+#define MAX_PLATFORM_CHECK_FILES 2
+static const char *RTLQuickCheckFiles[][MAX_PLATFORM_CHECK_FILES] = {
+    /* ppc64 has multiple quick check files */
+    {"/sys/firmware/devicetree/base/ibm,firmware-versions/open-power",
+     "/sys/firmware/devicetree/base/cpus/ibm,powerpc-cpu-features"},
+    /* acpi is unique to x86       */ {"/sys/firmware/acpi"},
+    /* nvidia0 is unique with cuda */ {"/dev/nvidia0"},
+    /* kfd is unique to amdgcn     */ {"/dev/kfd"},
+    /* More arm check files needed */ {"/sys/module/mdio_thunder/initstate"}};
+
 RTLsTy RTLs;
 std::mutex RTLsMtx;
 
@@ -50,21 +64,45 @@
     return;
   }
 
+  // Load plugins from same directory as libomptarget.so
+  std::string full_plugin_name;
+  void *handle = dlopen("libomptarget.so", RTLD_NOW);
+  if (!handle)
+    DP("dlopen() failed: %s\n", dlerror());
+  char *libomptarget_dir_name = new char[256];
+  if (dlinfo(handle, RTLD_DI_ORIGIN, libomptarget_dir_name) == -1)
+    DP("RTLD_DI_ORIGIN failed: %s\n", dlerror());
+  struct stat stat_buffer;
+  int platform_num = 0;
+
   DP("Loading RTLs...\n");
 
   // Attempt to open all the plugins and, if they exist, check if the interface
   // is correct and if they are supporting any devices.
   for (auto *Name : RTLNames) {
-    DP("Loading library '%s'...\n", Name);
-    void *dynlib_handle = dlopen(Name, RTLD_NOW);
+
+    // Only one quick check file required to attempt to load platform plugin
+    bool found = false;
+    for (auto *QuickCheckName : RTLQuickCheckFiles[platform_num++]) {
+      if (QuickCheckName) {
+        if (!strcmp(QuickCheckName, "") ||
+            (stat(QuickCheckName, &stat_buffer) == 0))
+          found = true;
+      }
+    }
+    if (!found) // Not finding quick check files is a faster fail than dlopen
+      continue;
+    full_plugin_name.assign(libomptarget_dir_name).append("/").append(Name);
+    DP("Loading library '%s'...\n", full_plugin_name.c_str());
+    void *dynlib_handle = dlopen(full_plugin_name.c_str(), RTLD_NOW);
 
     if (!dynlib_handle) {
       // Library does not exist or cannot be found.
-      DP("Unable to load library '%s': %s!\n", Name, dlerror());
+      DP("Unable to load '%s': %s!\n", full_plugin_name.c_str(), dlerror());
       continue;
     }
 
-    DP("Successfully loaded library '%s'!\n", Name);
+    DP("Successfully loaded library '%s'!\n", full_plugin_name.c_str());
 
     // Retrieve the RTL information from the runtime library.
     RTLInfoTy R;
@@ -124,6 +162,7 @@
     AllRTLs.push_back(R);
   }
 
+  delete libomptarget_dir_name;
   DP("RTLs loaded!\n");
 
   return;


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