Patch both rela.plt and rela.dyn for hooks (#1128)

Author: krk

ddprof-lib/src/main/cpp/codeCache.cpp

@@ -1,17 +1,6 @@
 /*
- * Copyright 2016 Andrei Pangin
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
+ * Copyright The async-profiler authors
+ * SPDX-License-Identifier: Apache-2.0
  */
 
 #include "codeCache.h"
@@ -274,48 +263,88 @@ void CodeCache::findSymbolsByPrefix(std::vector<const char *> &prefixes,
   }
 }
 
-void CodeCache::addImport(void **entry, const char *name) {
-  switch (name[0]) {
-  case 'd':
-    if (strcmp(name, "dlopen") == 0) {
-      _imports[im_dlopen] = entry;
+void CodeCache::saveImport(ImportId id, void** entry) {
+    for (int ty = 0; ty < NUM_IMPORT_TYPES; ty++) {
+        if (_imports[id][ty] == nullptr) {
+            _imports[id][ty] = entry;
+            return;
+        }
     }
-    break;
-  case 'p':
-    if (strcmp(name, "pthread_create") == 0) {
-      _imports[im_pthread_create] = entry;
-    } else if (strcmp(name, "pthread_exit") == 0) {
-      _imports[im_pthread_exit] = entry;
-    } else if (strcmp(name, "pthread_setspecific") == 0) {
-      _imports[im_pthread_setspecific] = entry;
+}
+
+void CodeCache::addImport(void **entry, const char *name) {
+    switch (name[0]) {
+      case 'c':
+          if (strcmp(name, "calloc") == 0) {
+              saveImport(im_calloc, entry);
+          }
+          break;
+      case 'd':
+          if (strcmp(name, "dlopen") == 0) {
+              saveImport(im_dlopen, entry);
+          }
+          break;
+      case 'f':
+          if (strcmp(name, "free") == 0) {
+              saveImport(im_free, entry);
+          }
+          break;
+      case 'm':
+          if (strcmp(name, "malloc") == 0) {
+              saveImport(im_malloc, entry);
+          }
+          break;
+      case 'p':
+          if (strcmp(name, "pthread_create") == 0) {
+              saveImport(im_pthread_create, entry);
+          } else if (strcmp(name, "pthread_exit") == 0) {
+              saveImport(im_pthread_exit, entry);
+          } else if (strcmp(name, "pthread_setspecific") == 0) {
+              saveImport(im_pthread_setspecific, entry);
+          } else if (strcmp(name, "poll") == 0) {
+              saveImport(im_poll, entry);
+          }
+          break;
+      case 'r':
+          if (strcmp(name, "realloc") == 0) {
+              saveImport(im_realloc, entry);
+          }
+          break;
     }
-    break;
-  }
 }
 
 void **CodeCache::findImport(ImportId id) {
   if (!_imports_patchable) {
     makeImportsPatchable();
     _imports_patchable = true;
   }
-  return _imports[id];
+  return _imports[id][PRIMARY];
 }
 
 void CodeCache::patchImport(ImportId id, void *hook_func) {
-  void **entry = findImport(id);
+  if (!_imports_patchable) {
+        makeImportsPatchable();
+        _imports_patchable = true;
+    }
+
+    for (int ty = 0; ty < NUM_IMPORT_TYPES; ty++) {void **entry = _imports[id][ty];
   if (entry != NULL) {
     *entry = hook_func;
-  }
+  }}
 }
 
 void CodeCache::makeImportsPatchable() {
   void **min_import = (void **)-1;
   void **max_import = NULL;
   for (int i = 0; i < NUM_IMPORTS; i++) {
-    if (_imports[i] != NULL && _imports[i] < min_import)
-      min_import = _imports[i];
-    if (_imports[i] != NULL && _imports[i] > max_import)
-      max_import = _imports[i];
+    for (int j = 0; j < NUM_IMPORT_TYPES; j++) {
+            void** entry = _imports[i][j];
+            if (entry == NULL) continue;
+            if (entry < min_import)
+      min_import = entry;
+    if (entry > max_import)
+      max_import = entry;
+        }
   }
 
   if (max_import != NULL) {

ddprof-lib/src/main/cpp/codeCache.h

@@ -1,17 +1,6 @@
 /*
- * Copyright 2017 Andrei Pangin
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
+ * Copyright The async-profiler authors
+ * SPDX-License-Identifier: Apache-2.0
  */
 
 #ifndef _CODECACHE_H
@@ -35,9 +24,20 @@ enum ImportId {
   im_pthread_create,
   im_pthread_exit,
   im_pthread_setspecific,
+  im_poll,
+  im_malloc,
+  im_calloc,
+  im_realloc,
+  im_free,
   NUM_IMPORTS
 };
 
+enum ImportType {
+    PRIMARY,
+    SECONDARY,
+    NUM_IMPORT_TYPES
+};
+
 class NativeFunc {
 private:
   short _lib_index;
@@ -58,7 +58,7 @@ class NativeFunc {
     if (posix_memalign((void**)(&func), sizeof(NativeFunc*), sizeof(NativeFunc)) != 0) {
       return -1;
     }
-    return func->_lib_index; 
+    return func->_lib_index;
   }
 
   static bool isMarked(const char *name) { return from(name)->_mark != 0; }
@@ -100,7 +100,7 @@ class CodeCache {
   unsigned int _plt_offset;
   unsigned int _plt_size;
 
-  void **_imports[NUM_IMPORTS];
+  void **_imports[NUM_IMPORTS][NUM_IMPORT_TYPES];
   bool _imports_patchable;
   bool _debug_symbols;
 
@@ -113,6 +113,7 @@ class CodeCache {
 
   void expand();
   void makeImportsPatchable();
+    void saveImport(ImportId id, void** entry);
 
 public:
   explicit CodeCache(const char *name, short lib_index = -1,

ddprof-lib/src/main/cpp/symbols_linux.cpp

@@ -181,33 +181,34 @@ void ElfParser::parseDynamicSection() {
       loadSymbolTable(symtab, syment * nsyms, syment, strtab);
     }
 
-    if (rel != NULL && relsz != 0) {
-      // If a shared library is built without PLT (-fno-plt), relocation entries for imports
-      // can be found in .rela.dyn. However, if both sections exist, .rela.plt entries
-      // should take precedence, that's why we parse .rela.dyn first.
-      for (size_t offs = relcount * relent; offs < relsz; offs += relent) {
-        ElfRelocation *r = (ElfRelocation *)(rel + offs);
-        if (ELF_R_TYPE(r->r_info) == R_GLOB_DAT || ELF_R_TYPE(r->r_info) == R_ABS64) {
+    if (jmprel != NULL && pltrelsz != 0) {
+      // Parse .rela.plt table
+      for (size_t offs = 0; offs < pltrelsz; offs += relent) {
+        ElfRelocation *r = (ElfRelocation *)(jmprel + offs);
+
           ElfSymbol *sym = (ElfSymbol *)(symtab + ELF_R_SYM(r->r_info) * syment);
           if (sym->st_name != 0) {
             _cc->addImport((void **)(_base + r->r_offset), strtab + sym->st_name);
-          }
+
         }
       }
     }
 
-    if (jmprel != NULL && pltrelsz != 0) {
-      // Parse .rela.plt table
-      for (size_t offs = 0; offs < pltrelsz; offs += relent) {
-        ElfRelocation *r = (ElfRelocation *)(jmprel + offs);
+    if (rel != NULL && relsz != 0) {
+      // Relocation entries for imports can be found in .rela.dyn, for example
+      // if a shared library is built without PLT (-fno-plt). However, if both
+      // entries exist, addImport saves them both.
+      for (size_t offs = relcount * relent; offs < relsz; offs += relent) {
+        ElfRelocation *r = (ElfRelocation *)(rel + offs);
+                if (ELF_R_TYPE(r->r_info) == R_GLOB_DAT || ELF_R_TYPE(r->r_info) == R_ABS64) {
           ElfSymbol *sym =
               (ElfSymbol *)(symtab + ELF_R_SYM(r->r_info) * syment);
           if (sym->st_name != 0) {
             _cc->addImport((void **)(_base + r->r_offset),
                            strtab + sym->st_name);
           }
         }
-      }
+      }}
     }
 }
 

test/test/nativemem/malloc_plt_dyn.c

@@ -0,0 +1,25 @@
+/*
+ * Copyright The async-profiler authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+
+const int MALLOC_SIZE = 1999993;
+const int MALLOC_DYN_SIZE = 2000003;
+
+// A global pointer referencing malloc as data -> .rela.dyn
+static void* (*malloc_dyn)(size_t) = malloc;
+
+int main(void) {
+    // Direct call -> .rela.plt
+    void* p = malloc(MALLOC_SIZE);
+
+    void* q = malloc_dyn(MALLOC_DYN_SIZE);
+
+    free(p);
+    free(q);
+
+    return 0;
+}