[Python-checkins] bpo-32280: Store _PyRuntime in a named section (GH-4802)

[pablogsal]

https://github.com/python/cpython/commit/35002aa8f62dda1f79035e9904abdf476683e9be
commit: 35002aa8f62dda1f79035e9904abdf476683e9be
branch: main
author: Max Bélanger <aeromax at gmail.com>
committer: pablogsal <Pablogsal at gmail.com>
date: 2021-06-04T00:37:29+01:00
summary:

bpo-32280: Store _PyRuntime in a named section (GH-4802)

This commit stores the _PyRuntime structure in a section of the same name. This allows a debugging or crash reporting tool to quickly locate this structure at runtime without requiring the symbol table.

Co-authored-by: Pablo Galindo <pablogsal at gmail.com>

files:
M Python/pylifecycle.c

diff --git a/Python/pylifecycle.c b/Python/pylifecycle.c
index 2dbebe45fd4b0..d31a9c15fd1ec 100644
--- a/Python/pylifecycle.c
+++ b/Python/pylifecycle.c
@@ -17,6 +17,10 @@
 
 #include <locale.h>               // setlocale()
 
+#if defined(__APPLE__)
+#include <mach-o/loader.h>
+#endif
+
 #ifdef HAVE_SIGNAL_H
 #  include <signal.h>             // SIG_IGN
 #endif
@@ -34,7 +38,6 @@
        (PyObject_TypeCheck((op), &PyWindowsConsoleIO_Type))
 #endif
 
-
 #define PUTS(fd, str) _Py_write_noraise(fd, str, (int)strlen(str))
 
 
@@ -59,7 +62,30 @@ static void wait_for_thread_shutdown(PyThreadState *tstate);
 static void call_ll_exitfuncs(_PyRuntimeState *runtime);
 
 int _Py_UnhandledKeyboardInterrupt = 0;
-_PyRuntimeState _PyRuntime = _PyRuntimeState_INIT;
+
+/* The following places the `_PyRuntime` structure in a location that can be
+ * found without any external information. This is meant to ease access to the
+ * interpreter state for various runtime debugging tools, but is *not* an
+ * officially supported feature */
+
+#if defined(MS_WINDOWS)
+
+#pragma section("PyRuntime", read, write)
+__declspec(allocate("PyRuntime"))
+
+#elif defined(__APPLE__)
+
+__attribute__((
+    section(SEG_DATA ",PyRuntime")
+))
+
+#endif
+
+_PyRuntimeState _PyRuntime
+#if defined(__linux__) && (defined(__GNUC__) || defined(__clang__))
+__attribute__ ((section (".PyRuntime")))
+#endif
+= _PyRuntimeState_INIT;
 static int runtime_initialized = 0;
 
 PyStatus