diff options
| author | H.J. Lu <hjl.tools@gmail.com> | 2025-06-15 11:38:54 +0800 |
|---|---|---|
| committer | H.J. Lu <hjl.tools@gmail.com> | 2025-06-16 08:43:40 +0800 |
| commit | 81467d4b6168c7ce40d951d6b32e387109c0e5ae (patch) | |
| tree | d8d7261619e6a35f40e905b6b2a1874309dae40f /sysdeps/x86_64 | |
| parent | 27360ab9ea637de80ded9f0e0fe23ac0cc621b29 (diff) | |
elf: Add optimization barrier for __ehdr_start and _end
rtld.c has
extern const ElfW(Ehdr) __ehdr_start attribute_hidden;
...
_dl_rtld_map.l_map_start = (ElfW(Addr)) &__ehdr_start;
_dl_rtld_map.l_map_end = (ElfW(Addr)) _end;
As
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120653
shows, compiler may generate run-time relocation on __ehdr_start with
movq .LC0(%rip), %xmm0
...
.section .data.rel.ro.local,"aw"
.align 8
.LC0:
.quad __ehdr_start
This won't work before run-time relocation is finished in rtld.c. Add
optimization barrier to prevent run-time relocations against __ehdr_start
and _end.
Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
Reviewed-by: Sam James <sam@gentoo.org>
Diffstat (limited to 'sysdeps/x86_64')
| -rw-r--r-- | sysdeps/x86_64/Makefile | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/sysdeps/x86_64/Makefile b/sysdeps/x86_64/Makefile index 5723ec1847..e8f8a52eea 100644 --- a/sysdeps/x86_64/Makefile +++ b/sysdeps/x86_64/Makefile @@ -214,6 +214,24 @@ $(objpfx)tst-plt-rewrite2: $(objpfx)tst-plt-rewritemod2.so endif test-internal-extras += tst-gnu2-tls2mod1 + +tests-special += $(objpfx)check-rtld.out + +$(objpfx)rtld.reloc: $(objpfx)rtld.os + @rm -f $@T + LC_ALL=C $(READELF) -rW $< > $@T + test -s $@T + mv -f $@T $@ +common-generated += $(objpfx)rtld.reloc + +# Verify that there are no run-time relocations against __ehdr_start nor +# _end. +$(objpfx)check-rtld.out: $(objpfx)rtld.reloc + LC_ALL=C; \ + if grep -E "R_X86_64_64.*(__ehdr_start|_end)" $^ > $@; \ + then false; else true; fi; \ + $(evaluate-test) +generated += check-rtld.out endif # $(subdir) == elf ifeq ($(subdir),csu) |