[asan] add primitives that allow coroutine implementations

This patch adds the __sanitizer_start_switch_fiber and
__sanitizer_finish_switch_fiber methods inspired from what can be found here
https://github.com/facebook/folly/commit/2ea64dd24946cbc9f3f4ac3f6c6b98a486c56e73 .

These methods are needed when the compiled software needs to implement
coroutines, fibers or the like. Without a way to annotate them, when the program
jumps to a stack that is not the thread stack, __asan_handle_no_return shows a
warning about that, and the fake stack mechanism may free fake frames that are
still in use.

Author: blastrock (Philippe Daouadi)
Reviewed in http://reviews.llvm.org/D20913



git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@273260 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 20 insertions, 0 deletions

diff --git a/include/sanitizer/common_interface_defs.h b/include/sanitizer/common_interface_defs.h
index 49360f2af..7aa58e986 100644
--- a/include/sanitizer/common_interface_defs.h
+++ b/include/sanitizer/common_interface_defs.h
@@ -139,6 +139,26 @@ extern "C" {
   // `top_percent` should be between 1 and 100.
   // Experimental feature currently available only with asan on Linux/x86_64.
   void __sanitizer_print_memory_profile(size_t top_percent);
+
+  // Fiber annotation interface.
+  // Before switching to a different stack, one must call
+  // __sanitizer_start_switch_fiber with a pointer to the bottom of the
+  // destination stack and its size. When code starts running on the new stack,
+  // it must call __sanitizer_finish_switch_fiber to finalize the switch.
+  // The start_switch function takes a void** to store the current fake stack if
+  // there is one (it is needed when detect_stack_use_after_return is enabled).
+  // When restoring a stack, this pointer must be given to the finish_switch
+  // function. In most cases, this void* can be stored on the stack just before
+  // switching.  When leaving a fiber definitely, null must be passed as first
+  // argument to the start_switch function so that the fake stack is destroyed.
+  // If you do not want support for stack use-after-return detection, you can
+  // always pass null to these two functions.
+  // Note that the fake stack mechanism is disabled during fiber switch, so if a
+  // signal callback runs during the switch, it will not benefit from the stack
+  // use-after-return detection.
+  void __sanitizer_start_switch_fiber(void **fake_stack_save,
+                                      const void *bottom, size_t size);
+  void __sanitizer_finish_switch_fiber(void *fake_stack_save);
 #ifdef __cplusplus
 }  // extern "C"
 #endif