[llvm-bugs] [Bug 49810] New: ld.lld doesn't permit read-only relocations (-z text) as default compared to ld.bfd and ld.gold

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=49810

            Bug ID: 49810
           Summary: ld.lld doesn't permit read-only relocations (-z text)
                    as default compared to ld.bfd and ld.gold
           Product: lld
           Version: unspecified
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P
         Component: ELF
          Assignee: unassignedbugs at nondot.org
          Reporter: axel.y.rivera at intel.com
                CC: llvm-bugs at lists.llvm.org, smithp352 at googlemail.com

I noticed that lld doesn't allow to relocate read-only sections by default (-z
text), while ld.bfd and ld.gold does (-z notext). This behavior was mentioned
in the following changes: https://reviews.llvm.org/D30530 . This is the example
from the same code review but modified for 32bits.

test2> cat simple.s
foo:
.long foo

test2> llvm-mc -filetype=obj -triple=i386-pc-linux simple.s -o simple.o
test2> ld.lld -m elf_i386 simple.o -o simple -shared
ld.lld: error: can't create dynamic relocation R_386_32 against local symbol in
readonly segment; recompile object files with -fPIC or pass '-Wl,-z,notext' to
allow text relocations in the output
>>> defined in simple.o
>>> referenced by simple.o:(.text+0x0)

But it links successfully for ld.bfd and ld.gold:

test2> ld.bfd -m elf_i386 simple.o -o simple -shared
test2> ld.gold -m elf_i386 simple.o -o simple -shared

If I add -z text to ld.bfd and ld.gold then I get the same failure:

test2> ld.bfd -z text -m elf_i386 simple.o -o simple -shared
ld.bfd: simple.o: warning: relocation in read-only section `.text'
ld.bfd: read-only segment has dynamic relocations.

test2> ld.gold -z text -m elf_i386 simple.o -o simple -shared
ld.gold: error: read-only segment has dynamic relocations


As mentioned in the test case, I can use -z notext and link in lld:

test2> ld.lld -z notext -m elf_i386 simple.o -o simple -shared


Is there a reason why lld doesn't permit the relocation for read-only sections
by default compared to bfd and gold?

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