On February 9, 2026 7:11:25 PM PST, Xi Ruoyao <[email protected]> wrote: >On Mon, 2026-02-02 at 19:57 -0800, H. Peter Anvin wrote: >> That hack dates back from before the signal frame extension. It is no >> longer necessary. > >Unfortunately at least it seems libgcc unwinder does not handle the >signal frame extension properly. The code reads: > > fde = _Unwind_Find_FDE (context->ra + _Unwind_IsSignalFrame (context) - 1, > &context->bases); > if (fde == NULL) > { >#ifdef MD_FALLBACK_FRAME_STATE_FOR > /* Couldn't find frame unwind info for this function. Try a > target-specific fallback mechanism. This will necessarily > not provide a personality routine or LSDA. */ > return MD_FALLBACK_FRAME_STATE_FOR (context, fs); >#else > return _URC_END_OF_STACK; >#endif > } > > fs->pc = context->bases.func; > > cie = get_cie (fde); > insn = extract_cie_info (cie, context, fs); > >Thus, it indeed attempts to avoid subtracting 1 for a signal frame, but >... _Unwind_IsSignalFrame (context) actually extracts a flag in context >which will only be raised up by extract_cie_info. > >Or am I missing something here? >
Oh, good grief... How does this possibly work on non-x86 platforms?
