[PATCH] D15192: [safestack] Turn the OS X SafeStack runtime into a dynamic library

[Kuba Brecka via llvm-commits]

kubabrecka created this revision.
kubabrecka added reviewers: eugenis, pcc, kcc, samsonov.
kubabrecka added subscribers: llvm-commits, zaks.anna.

On OS X, the are two huge drawbacks to having a static library (.a) as a runtime:

1) Interceptors don't work -- and SafeStack relies on intercepting pthread_create.
2) Having multiple instrumented modules (frameworks, dylibs, bundles) in a single process is problematic and requires special care when building each module.

Let's make the runtime a dynamic library, just like the other sanitizers (ASan, TSan).

http://reviews.llvm.org/D15192

Files:
  projects/compiler-rt/lib/safestack/CMakeLists.txt
  tools/clang/lib/Driver/ToolChains.cpp
  tools/clang/lib/Driver/Tools.cpp

Index: projects/compiler-rt/lib/safestack/CMakeLists.txt
===================================================================
--- projects/compiler-rt/lib/safestack/CMakeLists.txt
+++ projects/compiler-rt/lib/safestack/CMakeLists.txt
@@ -9,13 +9,13 @@
 if(APPLE)
   # Build universal binary on APPLE.
   add_compiler_rt_runtime(clang_rt.safestack
-    STATIC
+    SHARED
     OS osx
     ARCHS ${SAFESTACK_SUPPORTED_ARCH}
     SOURCES ${SAFESTACK_SOURCES}
             $<TARGET_OBJECTS:RTInterception.osx>
             $<TARGET_OBJECTS:RTSanitizerCommon.osx>
-            $<TARGET_OBJECTS:RTSanitizerCommonNoLibc.osx>
+            $<TARGET_OBJECTS:RTSanitizerCommonLibc.osx>
     CFLAGS ${SAFESTACK_CFLAGS}
     PARENT_TARGET safestack)
 else()
Index: tools/clang/lib/Driver/Tools.cpp
===================================================================
--- tools/clang/lib/Driver/Tools.cpp
+++ tools/clang/lib/Driver/Tools.cpp
@@ -6958,15 +6958,6 @@
   if (!Args.hasArg(options::OPT_nostdlib, options::OPT_nostartfiles))
     getMachOToolChain().addStartObjectFileArgs(Args, CmdArgs);
 
-  // SafeStack requires its own runtime libraries
-  // These libraries should be linked first, to make sure the
-  // __safestack_init constructor executes before everything else
-  if (getToolChain().getSanitizerArgs().needsSafeStackRt()) {
-    getMachOToolChain().AddLinkRuntimeLib(Args, CmdArgs,
-                                          "libclang_rt.safestack_osx.a",
-                                          /*AlwaysLink=*/true);
-  }
-
   Args.AddAllArgs(CmdArgs, options::OPT_L);
 
   AddLinkerInputs(getToolChain(), Inputs, Args, CmdArgs);
Index: tools/clang/lib/Driver/ToolChains.cpp
===================================================================
--- tools/clang/lib/Driver/ToolChains.cpp
+++ tools/clang/lib/Driver/ToolChains.cpp
@@ -413,6 +413,8 @@
     AddLinkSanitizerLibArgs(Args, CmdArgs, "ubsan");
   if (Sanitize.needsTsanRt())
     AddLinkSanitizerLibArgs(Args, CmdArgs, "tsan");
+  if (Sanitize.needsSafeStackRt())
+    AddLinkSanitizerLibArgs(Args, CmdArgs, "safestack");
 
   // Otherwise link libSystem, then the dynamic runtime library, and finally any
   // target specific static runtime library.


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