[PATCH] RISC-V: Protect .got with relro

[Palmer Dabbelt]

On Mon, 25 Sep 2023 01:19:57 PDT (-0700), schwab@suse.de wrote:
> Move .got before .data so that it can be protected with -zrelro.  Also
> separate .got.plt from .got if -znow is not in effect; the first two words
> of .got.plt are placed within the relro region.
>
> ld:
> 	PR ld/30877
> 	* emulparams/elf32lriscv-defs.sh (DATA_GOT, SEPARATE_GOTPLT):
> 	Define.
> 	* emulparams/elf64lriscv-defs.sh (SEPARATE_GOTPLT): Define.
> ---
>  ld/emulparams/elf32lriscv-defs.sh | 4 ++++
>  ld/emulparams/elf64lriscv-defs.sh | 1 +
>  2 files changed, 5 insertions(+)
>
> diff --git a/ld/emulparams/elf32lriscv-defs.sh b/ld/emulparams/elf32lriscv-defs.sh
> index b823cedacab..016556168c3 100644
> --- a/ld/emulparams/elf32lriscv-defs.sh
> +++ b/ld/emulparams/elf32lriscv-defs.sh
> @@ -47,3 +47,7 @@ INITIAL_READONLY_SECTIONS="${RELOCATING+${CREATE_SHLIB-${INITIAL_READONLY_SECTIO
>  OTHER_END_SYMBOLS="${CREATE_SHLIB-__BSS_END__ = .;
>      __global_pointer$ = MIN(__SDATA_BEGIN__ + 0x800,
>  		            MAX(__DATA_BEGIN__ + 0x800, __BSS_END__ - 0x800));}"
> +
> +# Put .got before .data
> +DATA_GOT=" "
> +SEPARATE_GOTPLT="SIZEOF (.got.plt) >= 8 ? 8 : 0"
> diff --git a/ld/emulparams/elf64lriscv-defs.sh b/ld/emulparams/elf64lriscv-defs.sh
> index 84a700a5f58..ca15338428f 100644
> --- a/ld/emulparams/elf64lriscv-defs.sh
> +++ b/ld/emulparams/elf64lriscv-defs.sh
> @@ -1,2 +1,3 @@
>  source_sh ${srcdir}/emulparams/elf32lriscv-defs.sh
>  ELFSIZE=64
> +SEPARATE_GOTPLT="SIZEOF (.got.plt) >= 16 ? 16 : 0"

I think we also want something like this

diff --git a/ld/testsuite/ld-elf/binutils.exp b/ld/testsuite/ld-elf/binutils.exp
index 674e8e9a575..b38e29ed6fb 100644
--- a/ld/testsuite/ld-elf/binutils.exp
+++ b/ld/testsuite/ld-elf/binutils.exp
@@ -95,7 +95,6 @@ proc binutils_test { prog_name ld_options test {test_name ""} {readelf_options "
 			      || [istarget "mips*-*-*"] \
 			      || [istarget "nios2*-*-*"] \
 			      || [istarget "or1k-*-*"] \
-			      || [istarget "riscv*-*-*"] \
 			      || [istarget "sh*-*-*"] \
 			      || [istarget "x86_64-*-rdos*"])]
 	# Check if GNU_RELRO segment is generated.