* [RFC] DT_X86_64_PLT* dependency
@ 2023-09-29 15:16 H.J. Lu
2023-10-02 10:26 ` Florian Weimer
0 siblings, 1 reply; 3+ messages in thread
From: H.J. Lu @ 2023-09-29 15:16 UTC (permalink / raw)
To: GNU C Library
Hi,
I checked in a linker patch:
https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=832ca732b8a96ff9a3e7c4abf24098bf2a59a96d
to generate DT_X86_64_PLT, DT_X86_64_PLTSZ and DT_X86_64_PLTENT for
https://gitlab.com/x86-psABIs/x86-64-ABI/-/commit/6d824a52a42d173eb838b879616c1be5870b593e
When these tags are generated, the r_addend field of the R_X86_64_JUMP_SLOT
relocation stores the offset of the indirect branch instruction. However, glibc
versions which don't have this commit in glibc 2.36:
commit f8587a61892cbafd98ce599131bf4f103466f084
Author: H.J. Lu <hjl.tools@gmail.com>
Date: Fri May 20 19:21:48 2022 -0700
x86-64: Ignore r_addend for R_X86_64_GLOB_DAT/R_X86_64_JUMP_SLOT
According to x86-64 psABI, r_addend should be ignored for R_X86_64_GLOB_DAT
and R_X86_64_JUMP_SLOT. Since linkers always set their r_addends to 0, we
can ignore their r_addends.
Reviewed-by: Fangrui Song <maskray@google.com>
won't ignore the r_addend value in the R_X86_64_JUMP_SLOT relocation. Such
binaries will fail to run with these versions of glibc. I am working
on a linker patch
to add a glibc version dependency similar to GLIBC_ABI_DT_RELR for DT_RELR.
Although this commit has been backported to glibc 2.33/2.34/2.35
release branches,
there may be 2.33/2.34/2.35 glibc binaries without the fix. Should
binaries with
DT_X86_64_PLT tags depend on glibc 2.36 or 2.33?
Thanks.
--
H.J.
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [RFC] DT_X86_64_PLT* dependency
2023-09-29 15:16 [RFC] DT_X86_64_PLT* dependency H.J. Lu
@ 2023-10-02 10:26 ` Florian Weimer
2023-10-03 7:44 ` H.J. Lu
0 siblings, 1 reply; 3+ messages in thread
From: Florian Weimer @ 2023-10-02 10:26 UTC (permalink / raw)
To: H.J. Lu; +Cc: GNU C Library
* H. J. Lu:
> When these tags are generated, the r_addend field of the R_X86_64_JUMP_SLOT
> relocation stores the offset of the indirect branch instruction. However, glibc
> versions which don't have this commit in glibc 2.36:
>
> commit f8587a61892cbafd98ce599131bf4f103466f084
> Author: H.J. Lu <hjl.tools@gmail.com>
> Date: Fri May 20 19:21:48 2022 -0700
>
> x86-64: Ignore r_addend for R_X86_64_GLOB_DAT/R_X86_64_JUMP_SLOT
>
> According to x86-64 psABI, r_addend should be ignored for R_X86_64_GLOB_DAT
> and R_X86_64_JUMP_SLOT. Since linkers always set their r_addends to 0, we
> can ignore their r_addends.
>
> Reviewed-by: Fangrui Song <maskray@google.com>
>
> won't ignore the r_addend value in the R_X86_64_JUMP_SLOT relocation. Such
> binaries will fail to run with these versions of glibc. I am working
> on a linker patch
> to add a glibc version dependency similar to GLIBC_ABI_DT_RELR for DT_RELR.
> Although this commit has been backported to glibc 2.33/2.34/2.35
> release branches,
> there may be 2.33/2.34/2.35 glibc binaries without the fix.
Can we reuse the GLIBC_ABI_DT_RELR marker?
> Should binaries with DT_X86_64_PLT tags depend on glibc 2.36 or 2.33?
I don't understand this question. The binaries will run on any system
that has the marker symbol. Or do you suggest to use an existing glibc
symbol version?
Thanks,
Florian
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [RFC] DT_X86_64_PLT* dependency
2023-10-02 10:26 ` Florian Weimer
@ 2023-10-03 7:44 ` H.J. Lu
0 siblings, 0 replies; 3+ messages in thread
From: H.J. Lu @ 2023-10-03 7:44 UTC (permalink / raw)
To: Florian Weimer; +Cc: GNU C Library
[-- Attachment #1: Type: text/plain, Size: 1674 bytes --]
On Mon, Oct 2, 2023, 6:26 PM Florian Weimer <fweimer@redhat.com> wrote:
> * H. J. Lu:
>
> > When these tags are generated, the r_addend field of the
> R_X86_64_JUMP_SLOT
> > relocation stores the offset of the indirect branch instruction.
> However, glibc
> > versions which don't have this commit in glibc 2.36:
> >
> > commit f8587a61892cbafd98ce599131bf4f103466f084
> > Author: H.J. Lu <hjl.tools@gmail.com>
> > Date: Fri May 20 19:21:48 2022 -0700
> >
> > x86-64: Ignore r_addend for R_X86_64_GLOB_DAT/R_X86_64_JUMP_SLOT
> >
> > According to x86-64 psABI, r_addend should be ignored for
> R_X86_64_GLOB_DAT
> > and R_X86_64_JUMP_SLOT. Since linkers always set their r_addends to
> 0, we
> > can ignore their r_addends.
> >
> > Reviewed-by: Fangrui Song <maskray@google.com>
> >
> > won't ignore the r_addend value in the R_X86_64_JUMP_SLOT relocation.
> Such
> > binaries will fail to run with these versions of glibc. I am working
> > on a linker patch
> > to add a glibc version dependency similar to GLIBC_ABI_DT_RELR for
> DT_RELR.
> > Although this commit has been backported to glibc 2.33/2.34/2.35
> > release branches,
> > there may be 2.33/2.34/2.35 glibc binaries without the fix.
>
> Can we reuse the GLIBC_ABI_DT_RELR marker?
>
Do all versions of glibc with DT_RELR support
also ignore r_addend?
>
> > Should binaries with DT_X86_64_PLT tags depend on glibc 2.36 or 2.33?
>
> I don't understand this question. The binaries will run on any system
> that has the marker symbol. Or do you suggest to use an existing glibc
> symbol version?
>
Yes, I am planning to use existing glibc symbol
version.
> Thanks,
> Florian
>
H.J.
^ permalink raw reply [flat|nested] 3+ messages in thread
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2023-10-02 10:26 ` Florian Weimer
2023-10-03 7:44 ` H.J. Lu
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