[PATCH] s390: Bind defined symbol locally in PIE

[Andreas Krebbel]

Hi Jens,

On 11/4/25 2:23 PM, Jens Remus wrote:
> Symbols defined in PIE should be bound locally, the same as -shared
> -Bsymbolic.
>
> Port x86 commit 4e0c91e45402 ("Bind defined symbol locally in PIE")
> change of relocate_section as well as linker tests to s390.  Similar as
> done for other architectures with the following commits:
> - AArch64: ac33b731d214 ("[AArch64] Bind defined symbol locally in PIE")
> - ARM: 1dcb9720d62c ("[ARM] Bind defined symbol locally in PIE")
> - RISC-V: 39c7793ba8be ("RISC-V: Bind defined symbol locally in PIE")
> - x86: 4e0c91e45402 ("Bind defined symbol locally in PIE")
> With this change symbols defined in an executable (i.e. PDE or PIE) are
> bound locally, as they cannot be interposed.  In the same way as symbols
> defined in a shared library linked with -Bsymbolic are bound locally.
>
> This also ensures that all defined symbols are bound locally in
> static PIE.
>
> Do not port the x86 change of check_relocs (now scan_relocs).  None of
> the linker tests where the change in condition triggers (e.g. bootstrap,
> cdtest) produce different readelf -Wa output.  The change appears to
> affect accounting of space required for dynamic relocations.  Instead of
> accounting them in check_relocs and later filtering them away in
> allocate_dynrelocs, they would not get accounted in the first place:
> The change in the expression would only have an effect if the following
> conditions are all met in addition to PIE:  ALLOC, PC-relative
> relocation, global symbol, not defined weak, and defined regular.  In
> this specific case the accounting of the PC relative relocation in
> h->dyn_relocs would be skipped for PIE.  But allocate_dynrelocs later
> eliminates any PC-relative dynamic relocations if PIC (= PIE or shared
> library) and SYMBOL_CALLS_LOCAL.
>
> bfd/
> 	PR ld/33141
> 	* elf64-s390.c (elf_s390_relocate_section): Bind defined symbol
> 	locally in PIE.
>
> ld/testsuite/
> 	PR ld/33141
> 	* ld-s390/s390.exp: Add pr33141 tests.
> 	* ld-s390/pr33141.rd: New file.
> 	* ld-s390/pr33141a.s: Likewise.
> 	* ld-s390/pr33141b.s: Likewise.
>
> Signed-off-by: Jens Remus <jremus@linux.ibm.com>

Ok. Thanks!

Andreas

> ---
>   bfd/elf64-s390.c                |  3 +--
>   ld/testsuite/ld-s390/pr33141.rd |  5 +++++
>   ld/testsuite/ld-s390/pr33141a.s | 10 ++++++++++
>   ld/testsuite/ld-s390/pr33141b.s |  3 +++
>   ld/testsuite/ld-s390/s390.exp   | 14 ++++++++++++++
>   5 files changed, 33 insertions(+), 2 deletions(-)
>   create mode 100644 ld/testsuite/ld-s390/pr33141.rd
>   create mode 100644 ld/testsuite/ld-s390/pr33141a.s
>   create mode 100644 ld/testsuite/ld-s390/pr33141b.s
>
> diff --git a/bfd/elf64-s390.c b/bfd/elf64-s390.c
> index e87f063be695..d029edff3cda 100644
> --- a/bfd/elf64-s390.c
> +++ b/bfd/elf64-s390.c
> @@ -2973,8 +2973,7 @@ elf_s390_relocate_section (bfd *output_bfd,
>   			   || r_type == R_390_PC32
>   			   || r_type == R_390_PC32DBL
>   			   || r_type == R_390_PC64
> -			   || !bfd_link_pic (info)
> -			   || !SYMBOLIC_BIND (info, h)
> +			   || !(bfd_link_executable (info) || SYMBOLIC_BIND (info, h))
>   			   || !h->def_regular))
>   		{
>   		  outrel.r_info = ELF64_R_INFO (h->dynindx, r_type);
> diff --git a/ld/testsuite/ld-s390/pr33141.rd b/ld/testsuite/ld-s390/pr33141.rd
> new file mode 100644
> index 000000000000..7c7d277921c4
> --- /dev/null
> +++ b/ld/testsuite/ld-s390/pr33141.rd
> @@ -0,0 +1,5 @@
> +#readelf: -r --wide
> +
> +Relocation section '.rela.dyn' at offset 0x[0-9a-f]+ contains 1 entry:
> +    Offset             Info             Type               Symbol's Value  Symbol's Name \+ Addend
> +[0-9a-f]+ +[0-9a-f]+ +R_390_RELATIVE +[0-9a-f]+
> diff --git a/ld/testsuite/ld-s390/pr33141a.s b/ld/testsuite/ld-s390/pr33141a.s
> new file mode 100644
> index 000000000000..43241f5224e4
> --- /dev/null
> +++ b/ld/testsuite/ld-s390/pr33141a.s
> @@ -0,0 +1,10 @@
> +	.text
> +	.global _start
> +_start:
> +	.dc.a foo
> +	.data
> +	.globl foo
> +foo:
> +	.byte 0
> +
> +	.section	.note.GNU-stack
> diff --git a/ld/testsuite/ld-s390/pr33141b.s b/ld/testsuite/ld-s390/pr33141b.s
> new file mode 100644
> index 000000000000..897c149ce2ce
> --- /dev/null
> +++ b/ld/testsuite/ld-s390/pr33141b.s
> @@ -0,0 +1,3 @@
> +	.data
> +	.dc.a foo
> +	.section	.note.GNU-stack
> diff --git a/ld/testsuite/ld-s390/s390.exp b/ld/testsuite/ld-s390/s390.exp
> index eaf74c4c2347..014754f94862 100644
> --- a/ld/testsuite/ld-s390/s390.exp
> +++ b/ld/testsuite/ld-s390/s390.exp
> @@ -158,6 +158,20 @@ set s390xtests {
>        "-m elf64_s390" "" "-m64" {pr32969a.s pr32969c.s pr32969b.s}
>        {{objdump "-dzrj.text" pr32969_64-2.dd}}
>        "pr32969_64-2"}
> +    {"Build pr33141a.o"
> +     "" "" "-m64" { pr33141a.s }}
> +    {"Build pr33141b.so"
> +     "-m elf64_s390 -shared" "" "-m64" { pr33141b.s }
> +     {}
> +     "pr33141b.so"}
> +    {"Build pr33141"
> +     "-m elf64_s390 -pie -z notext tmpdir/pr33141a.o tmpdir/pr33141b.so" "" "-m64" {}
> +     {{readelf {-rW} pr33141.rd}}
> +     "pr33141"}
> +    {"Build pr33141.so"
> +     "-m elf64_s390 -shared -Bsymbolic -z notext" "" "-m64" { pr33141a.s }
> +     {{readelf {-rW} pr33141.rd}}
> +     "pr33141.so"}
>   }
>   
>   if { [istarget "s390-*-*"] || [istarget "s390x-*-*"] } {