From c72e5cd87dcb075782f9b6beea024b984f2e1130 Mon Sep 17 00:00:00 2001 From: Sandra Loosemore Date: Wed, 20 Nov 2019 19:10:40 -0700 Subject: Compile elf/rtld.c with -fno-tree-loop-distribute-patterns. In GCC 10, the default at -O2 is now -ftree-loop-distribute-patterns. This optimization causes GCC to "helpfully" convert the hand-written loop in _dl_start into a call to memset, which is not available that early in program startup. Similar problems in other places in GLIBC have been addressed by explicitly building with -fno-tree-loop-distribute-patterns, but this one may have been overlooked previously because it only affects targets where HAVE_BUILTIN_MEMSET is not defined. This patch fixes a bug observed on nios2-linux-gnu target that caused all programs to segv on startup. --- elf/Makefile | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/elf/Makefile b/elf/Makefile index 06688181e3..b05af5ce3a 100644 --- a/elf/Makefile +++ b/elf/Makefile @@ -65,6 +65,12 @@ CFLAGS-dl-runtime.c += -fexceptions -fasynchronous-unwind-tables CFLAGS-dl-lookup.c += -fexceptions -fasynchronous-unwind-tables CFLAGS-dl-iterate-phdr.c += $(uses-callbacks) +# On targets without __builtin_memset, rtld.c uses a hand-coded loop +# in _dl_start. Make sure this isn't turned into a call to regular memset. +ifeq (yes,$(have-loop-to-function)) +CFLAGS-rtld.c += -fno-tree-loop-distribute-patterns +endif + # Compile rtld itself without stack protection. # Also compile all routines in the static library that are elided from # the shared libc because they are in libc.a in the same way. -- cgit 1.4.1