Add support for custom loaders to the sanitizer symbolizer

Summary:
Adds a fallback mode to procmaps when the symbolizer
fails to locate a module for a given address by using
dl_iterate_phdr.

Reviewers: kubamracek, rnk, vitalybuka, eugenis

Reviewed By: eugenis

Subscribers: srhines, llvm-commits

Differential Revision: https://reviews.llvm.org/D37269

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@314713 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 12 insertions, 1 deletions

diff --git a/lib/sanitizer_common/sanitizer_linux_libcdep.cc b/lib/sanitizer_common/sanitizer_linux_libcdep.cc
index 0f420875d..0dc437585 100644
--- a/lib/sanitizer_common/sanitizer_linux_libcdep.cc
+++ b/lib/sanitizer_common/sanitizer_linux_libcdep.cc
@@ -474,7 +474,7 @@ static bool requiresProcmaps() {
 }
 
 static void procmapsInit(InternalMmapVectorNoCtor<LoadedModule> *modules) {
-  MemoryMappingLayout memory_mapping(false);
+  MemoryMappingLayout memory_mapping(/*cache_enabled*/true);
   memory_mapping.DumpListOfModules(modules);
 }
 
@@ -488,6 +488,17 @@ void ListOfModules::init() {
   }
 }
 
+// When a custom loader is used, dl_iterate_phdr may not contain the full
+// list of modules. Allow callers to fall back to using procmaps.
+void ListOfModules::fallbackInit() {
+  if (!requiresProcmaps()) {
+    clearOrInit();
+    procmapsInit(&modules_);
+  } else {
+    clear();
+  }
+}
+
 // getrusage does not give us the current RSS, only the max RSS.
 // Still, this is better than nothing if /proc/self/statm is not available
 // for some reason, e.g. due to a sandbox.