Include vdso in the module list (#2695)

Adds vdso to the module list at init time.  Previously, it would be added
upon execution (via the module event trigger), but would otherwise be
absent.

I'd like to also add vsyscall, when it's separate, but it has no ELF header
and that complicates placing it on the module list, so for now we leave it
off.

Adds a release note as this could affect existing clients.

Tweaks drcovlib to handle displaced tags such as for the vsyscall hook.

api/docs/release.dox

@@ -190,6 +190,8 @@ Further non-compatibility-affecting changes include:
    sec_drcachesim_ops).
  - Added a last-level cache miss recording feature to drcachesim.
  - Added a delayed tracing feature to drcachesim.
+ - On Linux, the VDSO module is now included in the module list at program
+   startup.
 
 **************************************************
 <hr>

clients/drcov/postprocess/drcov2lcov.cpp

@@ -1160,17 +1160,21 @@ enumerate_line_info(void)
         hash_entry_t *e;
         drsym_error_t res;
         for (e = module_htable.table[i]; e != NULL; e = e->next) {
+            bool has_lines = true;
             num_entries++;
             PRINT(3, "Enumerate line info for %s\n", (char *)e->key);
             if (strcmp((char *)e->key, "<unknown>") == 0)
                 continue;
             if (e->payload == MODULE_TABLE_IGNORE)
                 continue;
             res = drsym_enumerate_lines((const char *)e->key, enum_line_cb, e->payload);
-            if (res != DRSYM_SUCCESS)
+            if (res != DRSYM_SUCCESS) {
                 WARN(1, "Failed to enumerate lines for %s\n", (char *)e->key);
+                has_lines = false;
+            }
             res = drsym_free_resources((char *)e->key);
-            if (res != DRSYM_SUCCESS)
+            /* I'm using has_lines to avoid warning on vdso. */
+            if (res != DRSYM_SUCCESS && has_lines)
                 WARN(1, "Failed to free resource for %s\n", (char *)e->key);
         }
     }

core/module_list.c

@@ -1,5 +1,5 @@
 /* **********************************************************
- * Copyright (c) 2011-2015 Google, Inc.  All rights reserved.
+ * Copyright (c) 2011-2017 Google, Inc.  All rights reserved.
  * Copyright (c) 2008-2010 VMware, Inc.  All rights reserved.
  * **********************************************************/
 
@@ -261,9 +261,11 @@ module_list_add(app_pc base, size_t view_size, bool at_map, const char *filepath
             module_area_create(base, view_size, at_map, filepath _IF_UNIX(inode));
         ASSERT(ma != NULL);
 
-        LOG(GLOBAL, LOG_INTERP|LOG_VMAREAS, 1, "module %s ["PFX","PFX"] added\n",
+        LOG(GLOBAL, LOG_INTERP|LOG_VMAREAS, 1, "module %s |%s| ["PFX","PFX"] added\n",
             (GET_MODULE_NAME(&ma->names) == NULL) ? "<no name>" :
-            GET_MODULE_NAME(&ma->names), base, base+view_size);
+            GET_MODULE_NAME(&ma->names),
+            ma->names.file_name == NULL ? "<no file>" : ma->names.file_name,
+            base, base+view_size);
 
         /* note that while it would be natural to invoke the client module
          * load event since we have the data for it right here, the

core/unix/os.c

@@ -7776,25 +7776,22 @@ os_add_new_app_module(dcontext_t *dcontext, bool at_map,
     memquery_iterator_start(&iter, base, true /* plan to alloc a module_area_t */);
     while (memquery_iterator_next(&iter)) {
         if (iter.vm_start == base) {
-            if (iter.vm_start == vsyscall_page_start) {
-                ASSERT_CURIOSITY(!at_map);
-            } else {
-                ASSERT_CURIOSITY(iter.inode != 0 || base == vdso_page_start);
-                ASSERT_CURIOSITY(iter.offset == 0); /* first map shouldn't have offset */
-                /* XREF 307599 on rounding module end to the next PAGE boundary */
-                ASSERT_CURIOSITY((iter.vm_end - iter.vm_start ==
-                                  ALIGN_FORWARD(size, PAGE_SIZE)));
-                inode = iter.inode;
-                filename = dr_strdup(iter.comment HEAPACCT(ACCT_OTHER));
-                found_map = true;
-            }
+            ASSERT_CURIOSITY(iter.inode != 0 || base == vdso_page_start ||
+                             base == vsyscall_page_start);
+            ASSERT_CURIOSITY(iter.offset == 0); /* first map shouldn't have offset */
+            /* XREF 307599 on rounding module end to the next PAGE boundary */
+            ASSERT_CURIOSITY((iter.vm_end - iter.vm_start ==
+                              ALIGN_FORWARD(size, PAGE_SIZE)));
+            inode = iter.inode;
+            filename = dr_strdup(iter.comment HEAPACCT(ACCT_OTHER));
+            found_map = true;
             break;
         }
     }
     memquery_iterator_stop(&iter);
 #ifdef HAVE_MEMINFO
-    /* barring weird races we should find this map except [vdso] */
-    ASSERT_CURIOSITY(found_map || base == vsyscall_page_start || base == vdso_page_start);
+    /* barring weird races we should find this map except */
+    ASSERT_CURIOSITY(found_map);
 #else /* HAVE_MEMINFO */
     /* Without /proc/maps or other memory querying interface available at
      * library map time, there is no way to find out the name of the file
@@ -9014,6 +9011,14 @@ find_executable_vm_areas(void)
                              strlen(VSYSCALL_REGION_MAPS_NAME)) == 0)
                 vsyscall_page_start = iter.vm_start;
 # endif
+            /* We'd like to add vsyscall to the module list too but when it's
+             * separate from vdso it has no ELF header which is too complex
+             * to force into the module list.
+             */
+            if (module_is_header(iter.vm_start, iter.vm_end - iter.vm_start)) {
+                module_list_add(iter.vm_start, iter.vm_end - iter.vm_start,
+                                false, iter.comment, iter.inode);
+            }
         } else if (mmap_check_for_module_overlap(iter.vm_start, size,
                                                  TEST(MEMPROT_READ, iter.prot),
                                                  iter.inode, false)) {

ext/drcovlib/drcovlib.c

@@ -1,5 +1,5 @@
 /* ***************************************************************************
- * Copyright (c) 2012-2016 Google, Inc.  All rights reserved.
+ * Copyright (c) 2012-2017 Google, Inc.  All rights reserved.
  * ***************************************************************************/
 
 /*
@@ -328,7 +328,7 @@ event_basic_block_analysis(void *drcontext, void *tag, instrlist_t *bb,
 {
     per_thread_t *data;
     instr_t *instr;
-    app_pc start_pc, end_pc;
+    app_pc tag_pc, start_pc, end_pc;
 
     /* do nothing for translation */
     if (translating)
@@ -340,7 +340,11 @@ event_basic_block_analysis(void *drcontext, void *tag, instrlist_t *bb,
      * transfer instructions, which is true for default options passed
      * to DR but not for -opt_speed.
      */
-    start_pc = dr_fragment_app_pc(tag);
+    /* We separate the tag from the instr pc ranges to handle displaced code
+     * such as for the vsyscall hook.
+     */
+    tag_pc = dr_fragment_app_pc(tag);
+    start_pc = instr_get_app_pc(instrlist_first_app(bb));
     end_pc   = start_pc; /* for finding the size */
     for (instr  = instrlist_first_app(bb);
          instr != NULL;
@@ -361,7 +365,7 @@ event_basic_block_analysis(void *drcontext, void *tag, instrlist_t *bb,
      * 4. The duplication can be easily handled in a post-processing step,
      *    which is required anyway.
      */
-    bb_table_entry_add(drcontext, data, start_pc, (uint)(end_pc - start_pc));
+    bb_table_entry_add(drcontext, data, tag_pc, (uint)(end_pc - start_pc));
 
     if (go_native)
         return DR_EMIT_GO_NATIVE;

suite/tests/client-interface/events.dll.c

@@ -1,5 +1,5 @@
 /* **********************************************************
- * Copyright (c) 2011-2013 Google, Inc.  All rights reserved.
+ * Copyright (c) 2011-2017 Google, Inc.  All rights reserved.
  * Copyright (c) 2008-2010 VMware, Inc.  All rights reserved.
  * **********************************************************/
 
@@ -41,6 +41,7 @@
 
 #ifdef UNIX
 # include <signal.h>
+# include <string.h>
 #endif
 
 #ifdef WINDOWS
@@ -322,7 +323,7 @@ void module_load_event_perm(void *drcontext, const module_data_t *info, bool loa
     else if (info->full_path[0] == '\\' || info->full_path[1] != ':')
         dr_fprintf(STDERR, "ERROR: full_path is not in DOS format: %s\n", info->full_path);
 #else
-    else if (info->full_path[0] != '/')
+    else if (info->full_path[0] != '/' && strcmp(info->full_path, "[vdso]") != 0)
         dr_fprintf(STDERR, "ERROR: full_path is not absolute: %s\n", info->full_path);
 #endif
 }