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| author | Sandra Loosemore <sandra@codesourcery.com> | 2019-11-20 19:10:40 -0700 |
|---|---|---|
| committer | Florian Weimer <fweimer@redhat.com> | 2019-11-26 19:18:23 +0100 |
| commit | c72e5cd87dcb075782f9b6beea024b984f2e1130 (patch) | |
| tree | 5775f299eaf17d56b80ff23f1a92e6f45925265a /elf | |
| parent | cc0e0b097c3e2176b51c32c09a76766e890cd2d4 (diff) | |
| download | glibc-c72e5cd87dcb075782f9b6beea024b984f2e1130.tar.gz | |
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.
Diffstat (limited to 'elf')
| -rw-r--r-- | elf/Makefile | 6 |
1 files changed, 6 insertions, 0 deletions
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. |