From cc9cac9f073a9517f5b7fcffcb7c28b166339491 Mon Sep 17 00:00:00 2001 From: Sandra Loosemore Date: Thu, 11 Jan 2024 21:12:56 +0000 Subject: [PATCH] libgcc, nios2: Fix exception handling on nios2 with -fpic Exception handling on nios2-linux-gnu with -fpic has been broken since revision 790854ea7670f11c14d431c102a49181d2915965, "Use _dl_find_object in _Unwind_Find_FDE". For whatever reason, this doesn't work on nios2. Nios2 uses the GOT address as the base for DW_EH_PE_datarel relocations in PIC; see my previous fix to make this work, revision 2d33dcfe9f0494c9b56a8d704c3d27c5a4329ebc, "Support for GOT-relative DW_EH_PE_datarel encoding". So this may be a horrible bug in the ABI or in my interpretation of it or just glibc's implementation of _dl_find_object for this target, but there's existing code out there that does things this way; and realistically, nobody is going to re-engineer this now that the vendor has EOL'ed the nios2 architecture. So, just skip over the code trying to use _dl_find_object on this target and fall back to the way that works. I plan to backport this patch to the GCC 12 and GCC 13 branches as well. libgcc/ChangeLog * unwind-dw2-fde-dip.c (_Unwind_Find_FDE): Do not try to use _dl_find_object on nios2; it doesn't work. --- libgcc/unwind-dw2-fde-dip.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/libgcc/unwind-dw2-fde-dip.c b/libgcc/unwind-dw2-fde-dip.c index 2f2ca35d549..57d0c8812b1 100644 --- a/libgcc/unwind-dw2-fde-dip.c +++ b/libgcc/unwind-dw2-fde-dip.c @@ -543,8 +543,9 @@ _Unwind_Find_FDE (void *pc, struct dwarf_eh_bases *bases) return ret; /* Use DLFO_STRUCT_HAS_EH_DBASE as a proxy for the existence of a glibc-style - _dl_find_object function. */ -#ifdef DLFO_STRUCT_HAS_EH_DBASE + _dl_find_object function. However, do not use _dl_find_object on nios2, + which uses the GOT address as the base for DW_EH_PE_datarel instead. */ +#if defined(DLFO_STRUCT_HAS_EH_DBASE) && !defined(__nios2__) { struct dl_find_object dlfo; if (_dl_find_object (pc, &dlfo) == 0 && dlfo.dlfo_eh_frame != NULL)