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To address this problem, this > > commit skips such objfiles. > >=20 > > As for the test, I initially tried to use temporary breakpoint and then > > 'continue' to get out of the jitted code but this for some reason did > > not trigger the crash. Using 'finish' to get out of jitted code followe= d > > by 'next' triggered it. >=20 > I tried it here and here's what I saw. So "next" is stepping over the > "function_add" function. While "next"ing, GDB stops at the first instruc= tion of > function_add, and looks at the frame's type, which runs all the frame sni= ffers > looking for one that claims the frame, including the DWARF unwinder, and = here is > where we run into the crash: >=20 > $ gdb ... > (gdb) start > ... > Temporary breakpoint 1, main (argc=3D1, argv=3D0x7fffffffdc08) at /home/p= edro/gdb/binutils-gdb/src/gdb/testsuite/gdb.base/jit-reader-host.c:58 > 58 struct jithost_abi *symfile =3D malloc (sizeof (struct jithost_= abi)); > (gdb) jit-reader-load /home/pedro/gdb/binutils-gdb/build/gdb/testsuite/ou= tputs/gdb.base/jit-reader/jit-reader.so > (gdb) b 95 > Breakpoint 2 at 0x555555555322: file /home/pedro/gdb/binutils-gdb/src/gdb= /testsuite/gdb.base/jit-reader-host.c, line 95. > (gdb) c > Continuing. >=20 > Program received signal SIGTRAP, Trace/breakpoint trap. > 0x00007ffff7ffb001 in jit_function_stack_mangle () > (gdb) c > Continuing. >=20 > Breakpoint 2, main (argc=3D1, argv=3D0x7fffffffdc08) at /home/pedro/gdb/b= inutils-gdb/src/gdb/testsuite/gdb.base/jit-reader-host.c:95 > 95 function_add (5, 6); > (gdb) set debug infrun 1 > (gdb) n >=20 > ... > [infrun] start_step_over: exit > [infrun] context_switch: Switching context from 0.0.0 to 353387.353387.= 0 > [infrun] handle_signal_stop: stop_pc=3D0x7ffff7ffb00a > ... >=20 >=20 > Thread 1 "gdb" received signal SIGSEGV, Segmentation fault. > 0x00005555559886c8 in bfd_usrdata (abfd=3D0x0) at ../bfd/bfd.h:6919 > 6919 return abfd->usrdata; > (top-gdb) bt > #0 0x00005555559886c8 in bfd_usrdata (abfd=3D0x0) at ../bfd/bfd.h:6919 > #1 0x000055555598a65f in gdb_bfd_requires_relocations (abfd=3D0x0) at /h= ome/pedro/gdb/binutils-gdb/src/gdb/gdb_bfd.c:1030 > #2 0x0000555555885dbb in find_comp_unit (objfile=3D0x5555565a6170) at /h= ome/pedro/gdb/binutils-gdb/src/gdb/dwarf2/frame.c:1538 > #3 0x0000555555885efa in dwarf2_frame_find_fde (pc=3D0x7fffffffd008, out= _per_objfile=3D0x0) at /home/pedro/gdb/binutils-gdb/src/gdb/dwarf2/frame.c:= 1568 > #4 0x0000555555885591 in dwarf2_frame_sniffer (self=3D0x555556426440 , this_frame=3D0x555556d6b7f0, this_cache=3D0x555556d6b80= 8) at /home/pedro/gdb/binutils-gdb/src/gdb/dwarf2/frame.c:1254 > #5 0x0000555555979639 in frame_unwind_try_unwinder (this_frame=3D0x55555= 6d6b7f0, this_cache=3D0x555556d6b808, unwinder=3D0x555556426440 ) at /home/pedro/gdb/binutils-gdb/src/gdb/frame-unwind.c:131 > #6 0x000055555597991a in frame_unwind_find_by_frame (this_frame=3D0x5555= 56d6b7f0, this_cache=3D0x555556d6b808) at /home/pedro/gdb/binutils-gdb/src/= gdb/frame-unwind.c:203 > #7 0x0000555555980948 in get_frame_type (frame=3D0x555556d6b7f0) at /hom= e/pedro/gdb/binutils-gdb/src/gdb/frame.c:2817 > #8 0x0000555555a2187b in process_event_stop_test (ecs=3D0x7fffffffd7c0) = at /home/pedro/gdb/binutils-gdb/src/gdb/infrun.c:6966 > #9 0x0000555555a20b3f in handle_signal_stop (ecs=3D0x7fffffffd7c0) at /h= ome/pedro/gdb/binutils-gdb/src/gdb/infrun.c:6585 > #10 0x0000555555a1ec37 in handle_inferior_event (ecs=3D0x7fffffffd7c0) at= /home/pedro/gdb/binutils-gdb/src/gdb/infrun.c:5837 > ... >=20 > That get_frame_type call is from here: >=20 > 6963 if (ecs->event_thread->control.step_range_end !=3D 1 > 6964 && (ecs->event_thread->control.step_over_calls =3D=3D STEP_= OVER_UNDEBUGGABLE > 6965 || ecs->event_thread->control.step_over_calls =3D=3D ST= EP_OVER_ALL) > 6966 && get_frame_type (frame) =3D=3D SIGTRAMP_FRAME) > 6967 { > 6968 infrun_debug_printf ("stepped into signal trampoline"); >=20 >=20 >=20 > OK, that makes sense. We stopped at 0x7ffff7ffb00a, which is function_ad= d, and GDB tried to get info > about the current frame. =20 >=20 > This means that we can write a more targeted testcase that does not rely = on how "next" works. > What is important is that we trigger the unwinding machinery inside the "= function_add" function. >=20 Ah, I see now why I was puzzled why it did not work for me. The important b= it (which I missed) is that in the test the JIT reader unwinder does not unwind function_add, *onl= y* jit_function_stack_mangle, so it falls to back DWARF unwinder which then hit the objfile with no BFD. = If I stop in main, it would likely find an objfile for the PC before hitting the JIT objfile so it won'= t trigger the crash. Thanks!=C2=A0 I'll send v2 with updated testcase and commit message shortly. > So... >=20 > (gdb) jit-reader-load /home/pedro/gdb/binutils-gdb/build/gdb/testsuite/ou= tputs/gdb.base/jit-reader/jit-reader.so > (gdb) b 95 > Breakpoint 1 at 0x1322: file /home/pedro/gdb/binutils-gdb/src/gdb/testsui= te/gdb.base/jit-reader-host.c, line 95. > (gdb) r > Starting program: /home/pedro/gdb/binutils-gdb/build/gdb/testsuite/output= s/gdb.base/jit-reader/jit-reader=20 >=20 > Program received signal SIGTRAP, Trace/breakpoint trap. > 0x00007ffff7ffb001 in jit_function_stack_mangle () > (gdb) c > Continuing. >=20 > Breakpoint 1, main (argc=3D1, argv=3D0x7fffffffdc08) at /home/pedro/gdb/b= inutils-gdb/src/gdb/testsuite/gdb.base/jit-reader-host.c:95 > 95 function_add (5, 6); > (gdb) b *function_add > Breakpoint 2 at 0x7ffff7ffb00a > (gdb) c > Continuing. >=20 > Thread 1 "gdb" received signal SIGSEGV, Segmentation fault. > 0x00005555559886c8 in bfd_usrdata (During symbol reading: incomplete CFI = data; unspecified registers (e.g., rax) at 0x5555559886d0 > abfd=3D0x0) at ../bfd/bfd.h:6919 > 6919 return abfd->usrdata; > (top-gdb)=20 >=20 >=20 > So in a nutshell, it would be better for the test to do: >=20 > fin > b *function_add > c << this crashes as GDB prints the current frame > bt << add this for good measure. >=20 > Instead of: >=20 > fin > bt << not clear what this is for > next << reaches the unwinder today, triggering the crash, but who knows= the future