add tracing on linux and freebsd

CMakeLists.txt

@@ -21,10 +21,14 @@ option(MI_BUILD_OBJECT      "Build object library" ON)
 option(MI_BUILD_TESTS       "Build test executables" ON)
 option(MI_DEBUG_TSAN        "Build with thread sanitizer (needs clang)" OFF)
 option(MI_DEBUG_UBSAN       "Build with undefined-behavior sanitizer (needs clang++)" OFF)
+option(MI_DEBUG_TRACE       "Store allocation stack trace in each heap block to debug heap block overflows or corruption" OFF)
 option(MI_CHECK_FULL        "Use full internal invariant checking in DEBUG mode (deprecated, use MI_DEBUG_FULL instead)" OFF)
 option(MI_INSTALL_TOPLEVEL  "Install directly into $CMAKE_INSTALL_PREFIX instead of PREFIX/lib/mimalloc-version" OFF)
 option(MI_USE_LIBATOMIC     "Explicitly link with -latomic (on older systems)" OFF)
 
+set(MI_PADDING_EXTRA 0 CACHE STRING "Specify extra bytes for padding in each heap block (to debug heap block overflows)")
+
+
 include(GNUInstallDirs)
 include("cmake/mimalloc-config-version.cmake")
 
@@ -120,6 +124,21 @@ if(MI_DEBUG_FULL)
   list(APPEND mi_defines MI_DEBUG=3)   # full invariant checking
 endif()
 
+if(MI_DEBUG_TRACE)
+  if (APPLE)
+    message(WARNING "Cannot enable MI_DEBUG_TRACE on Apple")
+    set(MI_DEBUG_TRACE OFF)
+  else()    
+    message(STATUS "Enable allocation trace in each heap block (MI_DEBUG_TRACE=ON)")
+    list(APPEND mi_defines MI_DEBUG_TRACE=1) 
+  endif()
+endif()
+
+if(MI_PADDING_EXTRA)
+  message(STATUS "Add extra debug padding to each heap block (MI_PADDING_EXTRA=${MI_PADDING_EXTRA})")
+  list(APPEND mi_defines MI_PADDING_EXTRA=${MI_PADDING_EXTRA}) 
+endif()
+
 if(NOT MI_PADDING)
   message(STATUS "Disable padding of heap blocks in debug mode (MI_PADDING=OFF)")
   list(APPEND mi_defines MI_PADDING=0)
@@ -212,9 +231,15 @@ if(WIN32)
 else()
   if(NOT ${CMAKE_C_COMPILER} MATCHES "android")
     list(APPEND mi_libraries pthread)
-    find_library(LIBRT rt)
-    if(LIBRT)
-      list(APPEND mi_libraries ${LIBRT})
+    find_library(MI_LIBRT rt)
+    if(MI_LIBRT)
+      list(APPEND mi_libraries ${MI_LIBRT})
+    endif()
+    if(MI_DEBUG_TRACE)
+      find_library(MI_LIBEXECINFO NAMES execinfo)  
+      if (MI_LIBEXECINFO)                            # on freeBSD
+        list(APPEND mi_libraries ${MI_LIBEXECINFO})
+      endif()
     endif()
   endif()
 endif()
@@ -270,6 +295,7 @@ else()
   message(STATUS "C Compiler       : ${CMAKE_C_COMPILER}")
 endif()
 message(STATUS "Compiler flags   : ${mi_cflags}")
+message(STATUS "Compiler defines : ${mi_defines}")
 message(STATUS "Build targets    : ${mi_build_targets}")
 message(STATUS "")
 

src/options.c

@@ -358,6 +358,7 @@ void _mi_stack_trace_capture(void** strace, size_t len, size_t skip) {
 #include <dbghelp.h>
 #pragma comment(lib,"dbghelp")
 void _mi_stack_trace_print(const void* const* strace, size_t len, const mi_block_t* block, size_t bsize, size_t avail) {
+  _mi_fprintf(NULL, NULL, "trace for block %p of size %zu (%zu total in block), allocated at:\n", block, avail, bsize);
   HANDLE current_process = GetCurrentProcess();
   SymInitialize(current_process, NULL, TRUE);
   PSYMBOL_INFO info = (PSYMBOL_INFO)_malloca(sizeof(SYMBOL_INFO) + 256 * sizeof(TCHAR));
@@ -365,7 +366,6 @@ void _mi_stack_trace_print(const void* const* strace, size_t len, const mi_block
   memset(info, 0, sizeof(info));
   info->MaxNameLen = 255;
   info->SizeOfStruct = sizeof(SYMBOL_INFO);
-  _mi_fprintf(NULL, NULL, "for block %p of %zu allocated bytes (%zu total in block), allocated at:\n", block, avail, bsize);
   for (size_t i = 0; i < len && strace[i] != NULL; i++) {
     if (SymFromAddr(current_process, (DWORD64)(strace[i]), 0, info)) {
       _mi_fprintf(NULL, NULL, "  frame %2zu: %8p: %s\n", i, strace[i], info->Name);
@@ -375,10 +375,37 @@ void _mi_stack_trace_print(const void* const* strace, size_t len, const mi_block
     }
   }  
 }
+#elif (MI_DEBUG_TRACE > 0) && (defined(__linux__) || defined(__FreeBSD__))
+#include <execinfo.h>
+#define MI_TRACE_LEN (64)
+void _mi_stack_trace_capture(void** strace, size_t len, size_t skip) {
+  if (_mi_preloading()) return;
+  if (!mi_recurse_enter()) return;
+  void* trace[MI_TRACE_LEN];
+  backtrace(trace, MI_TRACE_LEN);
+  skip += 4;
+  for (size_t i = 0; i < len; i++) {
+    void* p = (i + skip < MI_TRACE_LEN ? trace[i+skip] : NULL);
+    strace[i] = p;
+  }
+  mi_recurse_exit();
+}
+void _mi_stack_trace_print(const void* const* strace, size_t len, const mi_block_t* block, size_t bsize, size_t avail) {
+  _mi_fprintf(NULL, NULL, "trace for block %p of size %zu (%zu total in block), allocated at:\n", block, avail, bsize);
+  char** names = backtrace_symbols((void**)strace, len);
+  for (size_t i = 0; i < len && strace[i] != NULL; i++) {
+    _mi_fprintf(NULL, NULL, "  frame %2zu: %8p: %s\n", i, strace[i], (names[i] == NULL ? "<unknown>" : names[i]));
+  }  
+}
 #else 
-void _mi_capture_stack_trace(void** strace, size_t len, size_t skip) {
+void _mi_stack_trace_capture(void** strace, size_t len, size_t skip) {
   MI_UNUSED(strace); MI_UNUSED(len); MI_UNUSED(skip);  
 }
+void _mi_stack_trace_print(const void* const* strace, size_t len, const mi_block_t* block, size_t bsize, size_t avail) {
+  MI_UNUSED(strace); MI_UNUSED(len); MI_UNUSED(block);
+  MI_UNUSED(bsize); MI_UNUSED(avail);
+}
+
 #endif
 
 // --------------------------------------------------------

test/test-stress.c

@@ -103,6 +103,9 @@ static void* alloc_items(size_t items, random_t r) {
     for (uintptr_t i = 0; i < items; i++) {
       p[i] = (items - i) ^ cookie;
     }
+    if (pick(r)%1000 <= 1) {
+      p[items+1] = 42; // overflow
+    }
   }  
   return p;
 }