[PATCH] D17857: [ELF] - DT_TEXTREL/DF_TEXTREL flags implemented.

[Rui Ueyama via llvm-commits]

It sounds like reasonable to not submit this until a real need comes up. I
don't seems that we have an immediate need because the bug to create
relocations to RO sections has been fixed.

On Thu, Mar 3, 2016 at 12:03 PM, Rafael Espíndola <
rafael.espindola at gmail.com> wrote:

> Is this actually needed?
>
> It was noticed in freebsd because we were incorrectly creating text
> relocations. Short of bugs, is it actually common to have relocations
> pointing to text these days?
>
> Cheers,
> Rafael
>
>
> On 3 March 2016 at 13:27, George Rimar <grimar at accesssoftek.com> wrote:
> > grimar created this revision.
> > grimar added reviewers: ruiu, rafael.
> > grimar added subscribers: llvm-commits, grimar.
> >
> > This patch implements DT_TEXTREL/DF_TEXTREL flags. Actually I am not
> sure in current implementation and would be happy to know the side opinion
> about it.
> > Problem of that feature is that somehow we should know that relocation
> should cause a modification of read only segment.
> >
> > To do that I am checking that relocation OKind field is
> DynamicReloc<ELFT>::Off_Sec. Looks it is safe and correct way to use it for
> that ?
> > Also for simplification I am not iterating through sections in LOADs and
> just checking the read/write flag of output sections when adding
> relocations during Writer<ELFT>::scanRelocs().
> >
> > DT_TEXTREL description:
> > This member's absence signifies that no relocation entry should cause a
> modification to a non-writable segment, as specified by the segment
> permissions in the program header table. If this member is present, one or
> more relocation entries might request modifications to a non-writable
> segment, and the dynamic linker can prepare accordingly. This entry is at
> level 2. Its use has been superseded by the DF_TEXTREL flag.
> >
> > http://reviews.llvm.org/D17857
> >
> > Files:
> >   ELF/OutputSections.cpp
> >   ELF/OutputSections.h
> >   test/ELF/textrel.s
> >   test/ELF/tls-opt-iele-i686-nopic.s
> >
>
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