WIP: Make it possible to use nwind-capi as alternative unwinding backend

See also: koute/not-perf#37

CMakeLists.txt

@@ -105,6 +105,12 @@ else()
     set(QT_MIN_VERSION 5.10.0)
 endif()
 
+option(
+  HEAPTRACK_USE_NWIND_CAPI
+  "Use nwind_capi for unwind, see https://github.com/koute/not-perf"
+  OFF
+)
+
 option(
   HEAPTRACK_USE_LIBUNWIND
   "Define preferred unwind functionality - Libunwind as ON and unwind_tables as OFF."
@@ -151,7 +157,9 @@ if (ECM_ENABLE_SANITIZERS)
 endif()
 
 if (HEAPTRACK_BUILD_TRACK)
-    if (HEAPTRACK_USE_LIBUNWIND)
+    if (HEAPTRACK_USE_NWIND_CAPI)
+        find_package(nwind_capi REQUIRED)
+    elseif (HEAPTRACK_USE_LIBUNWIND)
         find_package(Libunwind REQUIRED)
     endif()
 

cmake/Findnwind_capi.cmake

@@ -0,0 +1,20 @@
+# SPDX-License-Identifier: MIT
+#
+# - Try to find nwind_capi library
+#
+# This will define
+# NWIND_CAPI_FOUND
+# NWIND_CAPI_INCLUDE_DIRS
+# NWIND_CAPI_LIBRARIES
+#
+
+find_path(NWIND_CAPI_INCLUDE_DIRS NAMES nwind_capi.h)
+find_library(NWIND_CAPI_LIBRARIES NAMES nwind_capi)
+
+include(FindPackageHandleStandardArgs)
+find_package_handle_standard_args(
+    NWIND_CAPI DEFAULT_MSG
+    NWIND_CAPI_LIBRARIES NWIND_CAPI_INCLUDE_DIRS
+)
+
+mark_as_advanced(NWIND_CAPI_INCLUDE_DIRS NWIND_CAPI_LIBRARIES)

src/track/CMakeLists.txt

@@ -7,7 +7,11 @@ install(PROGRAMS ${PROJECT_BINARY_DIR}/${BIN_INSTALL_DIR}/heaptrack
     DESTINATION ${BIN_INSTALL_DIR}
 )
 
-if (HEAPTRACK_USE_LIBUNWIND)
+if (HEAPTRACK_USE_NWIND_CAPI)
+    add_library(heaptrack_unwind STATIC trace_nwind_capi.cpp)
+    target_include_directories(heaptrack_unwind PRIVATE ${NWIND_CAPI_INCLUDE_DIRS})
+    target_link_libraries(heaptrack_unwind PRIVATE ${NWIND_CAPI_LIBRARIES})
+elseif (HEAPTRACK_USE_LIBUNWIND)
     add_library(heaptrack_unwind STATIC trace_libunwind.cpp)
     target_include_directories(heaptrack_unwind PRIVATE ${LIBUNWIND_INCLUDE_DIRS})
     target_link_libraries(heaptrack_unwind PRIVATE ${LIBUNWIND_LIBRARIES})

src/track/libheaptrack.cpp

@@ -381,6 +381,7 @@ class HeapTrack
             return;
         }
         s_data->moduleCacheDirty = true;
+        Trace::invalidateModuleCache();
     }
 
     void writeTimestamp()

src/track/trace.h

@@ -68,6 +68,7 @@ struct Trace
     }
 
     static void setup();
+    static void invalidateModuleCache();
 
     static void print();
 

src/track/trace_libunwind.cpp

@@ -62,6 +62,10 @@ void Trace::setup()
 #endif
 }
 
+void Trace::invalidateModuleCache()
+{
+}
+
 int Trace::unwind(void** data)
 {
     return unw_backtrace(data, MAX_SIZE);

src/track/trace_nwind_capi.cpp

@@ -0,0 +1,88 @@
+/*
+    SPDX-FileCopyrightText: 2014-2019 Milian Wolff <[email protected]>
+
+    SPDX-License-Identifier: LGPL-2.1-or-later
+*/
+
+/**
+ * @brief A libunwind based backtrace.
+ */
+
+#include "trace.h"
+
+#include <cstdio>
+
+#include <nwind_capi.h>
+
+namespace {
+struct AddressSpace
+{
+    AddressSpace()
+        : handle(nwind_create_local_address_space())
+    {
+        nwind_local_address_space_use_shadow_stack(handle, 1);
+    }
+
+    ~AddressSpace()
+    {
+        nwind_free_local_address_space(handle);
+    }
+
+    nwind_local_address_space* const handle;
+};
+
+nwind_local_address_space* addressSpace()
+{
+    static AddressSpace addressSpace;
+    return addressSpace.handle;
+}
+
+struct UnwindContext
+{
+    UnwindContext()
+        : handle(nwind_create_local_unwind_context())
+    {
+    }
+
+    ~UnwindContext()
+    {
+        nwind_free_local_unwind_context(handle);
+    }
+
+    nwind_local_unwind_context* const handle;
+};
+
+nwind_local_unwind_context* unwindContext()
+{
+    static thread_local UnwindContext unwindContext;
+    return unwindContext.handle;
+}
+}
+
+void Trace::print()
+{
+    Trace trace;
+    if (!trace.fill(1)) {
+        return;
+    }
+
+    unsigned frameNr = 0;
+    for (auto ip : trace) {
+        ++frameNr;
+        fprintf(stderr, "#%-2u %p\n", frameNr, ip);
+    }
+}
+
+void Trace::setup()
+{
+}
+
+void Trace::invalidateModuleCache()
+{
+    nwind_reload_local_address_space(addressSpace());
+}
+
+int Trace::unwind(void** data)
+{
+    return nwind_local_backtrace(addressSpace(), unwindContext(), data, MAX_SIZE);
+}

src/track/trace_unwind_tables.cpp

@@ -41,6 +41,10 @@ void Trace::setup()
 {
 }
 
+void Trace::invalidateModuleCache()
+{
+}
+
 void Trace::print()
 {
     Trace trace;