[3.12] gh-123967: Fix faulthandler for trampoline frames (#127329) (#127363)

gh-123967: Fix faulthandler for trampoline frames (#127329) If the top-most frame is a trampoline frame, skip it. (cherry picked from commit 58e334e)

Author: vstinner

Misc/NEWS.d/next/Library/2024-11-27-14-06-35.gh-issue-123967.wxUmnW.rst

@@ -0,0 +1,2 @@
+Fix faulthandler for trampoline frames. If the top-most frame is a
+trampoline frame, skip it. Patch by Victor Stinner.

Python/traceback.c

@@ -1242,6 +1242,8 @@ _Py_DumpASCII(int fd, PyObject *text)
 static void
 dump_frame(int fd, _PyInterpreterFrame *frame)
 {
+ assert(frame->owner != FRAME_OWNED_BY_CSTACK);
+
  PyCodeObject *code = frame->f_code;
  PUTS(fd, " File ");
  if (code->co_filename != NULL
@@ -1315,24 +1317,27 @@ dump_traceback(int fd, PyThreadState *tstate, int write_header)
 
  unsigned int depth = 0;
  while (1) {
+ if (frame->owner == FRAME_OWNED_BY_CSTACK) {
+ /* Trampoline frame */
+ frame = frame->previous;
+ if (frame == NULL) {
+ break;
+ }
+
+ /* Can't have more than one shim frame in a row */
+ assert(frame->owner != FRAME_OWNED_BY_CSTACK);
+ }
+
  if (MAX_FRAME_DEPTH <= depth) {
  PUTS(fd, " ...\n");
  break;
  }
+
  dump_frame(fd, frame);
  frame = frame->previous;
  if (frame == NULL) {
  break;
  }
- if (frame->owner == FRAME_OWNED_BY_CSTACK) {
- /* Trampoline frame */
- frame = frame->previous;
- }
- if (frame == NULL) {
- break;
- }
- /* Can't have more than one shim frame in a row */
- assert(frame->owner != FRAME_OWNED_BY_CSTACK);
  depth++;
  }
 }