Re: [PATCH] loongarch64: add relaxation support

[Daniel Kiper]

On Thu, May 25, 2023 at 09:05:20PM +0800, Xiaotian Wu wrote:
> The toolchain for the loongarch architecture will contain a series of patches 
> [1]
> in the next release to add relaxation support for the LoongArch.
>
> In order for the new toolchain to compile grub 2.12, support for relocation 
> types
> such as R_LARCH_B16, R_LARCH_B21 and R_LARCH_RELAX to be added.

s/to be added/have to be added/?

> [1]: https://sourceware.org/pipermail/binutils/2023-May/127539.html
>
> Signed-off-by: Xiaotian Wu <wuxiaotian@loongson.cn>
> ---
>  grub-core/kern/loongarch64/dl.c        | 17 ++++++++++++++
>  grub-core/kern/loongarch64/dl_helper.c | 32 +++++++++++++++++++++++++-
>  include/grub/elf.h                     |  3 +++
>  include/grub/loongarch64/reloc.h       |  2 ++
>  util/grub-mkimagexx.c                  | 24 ++++++++++++++++++-
>  util/grub-module-verifier.c            |  3 +++
>  6 files changed, 79 insertions(+), 2 deletions(-)
>
> diff --git a/grub-core/kern/loongarch64/dl.c b/grub-core/kern/loongarch64/dl.c
> index 43080e72e..4341bf5e4 100644
> --- a/grub-core/kern/loongarch64/dl.c
> +++ b/grub-core/kern/loongarch64/dl.c
> @@ -87,11 +87,28 @@ grub_arch_dl_relocate_symbols (grub_dl_t mod, void *ehdr,
>         }
>         break;
>       case R_LARCH_MARK_LA:
> +     case R_LARCH_RELAX:
>         break;
>       case R_LARCH_SOP_PUSH_PCREL:
>       case R_LARCH_SOP_PUSH_PLT_PCREL:
>         grub_loongarch64_sop_push (&stack, sym_addr - (grub_uint64_t)place);
>         break;
> +     case R_LARCH_B16:
> +       {
> +         grub_uint32_t *abs_place = place;
> +         grub_ssize_t off = sym_addr - (grub_addr_t) place;
> +
> +         grub_loongarch64_b16 (abs_place, off);
> +       }
> +       break;
> +     case R_LARCH_B21:
> +       {
> +         grub_uint32_t *abs_place = place;
> +         grub_ssize_t off = sym_addr - (grub_addr_t) place;
> +
> +         grub_loongarch64_b21 (abs_place, off);
> +       }
> +       break;
>       case R_LARCH_B26:
>         {
>           grub_uint32_t *abs_place = place;
> diff --git a/grub-core/kern/loongarch64/dl_helper.c 
> b/grub-core/kern/loongarch64/dl_helper.c
> index e8ec1219f..4d8d83a7e 100644
> --- a/grub-core/kern/loongarch64/dl_helper.c
> +++ b/grub-core/kern/loongarch64/dl_helper.c
> @@ -200,12 +200,42 @@ grub_loongarch64_sop_32_s_0_10_10_16_s2 
> (grub_loongarch64_stack_t stack,
>    *place =(*place) | ((a >> 18) & 0x3ff);
>  }
>
> +void grub_loongarch64_b16 (grub_uint32_t *place, grub_int64_t offset)
> +{
> +  grub_uint32_t val;
> +  const grub_uint32_t insmask = grub_cpu_to_le32_compile_time (0xfc0003ff);
> +
> +  grub_dprintf ("dl", "  reloc_b16 %p %c= 0x%llx\n",
> +             place, offset > 0 ? '+' : '-',
> +             offset < 0 ? (long long) -(unsigned long long) offset : offset);

Why do not use proper PRIxGRUB_INT64_T, etc. format specifiers? Then probably
you can drop these strange casts. Or at least cast to grub_* types. If both
do not work please add a comment why these casts are needed.

> +  val = ((offset >> 2) & 0xffff) << 10;
> +
> +  *place &= insmask;
> +  *place |= grub_cpu_to_le32 (val) & ~insmask;
> +}
> +
> +void grub_loongarch64_b21 (grub_uint32_t *place, grub_int64_t offset)
> +{
> +  grub_uint32_t val;
> +  const grub_uint32_t insmask = grub_cpu_to_le32_compile_time (0xfc0003e0);
> +
> +  grub_dprintf ("dl", "  reloc_b21 %p %c= 0x%llx\n",
> +             place, offset > 0 ? '+' : '-',
> +             offset < 0 ? (long long) -(unsigned long long) offset : offset);

Ditto and below please...

> +  val = ((offset >> 18) & 0x1f) | (((offset >> 2) & 0xffff) << 10);

Please define constants where possible. If not please add a comment what is
happening here and what these values mean. These kind of problems should
be fixed everywhere in this patch.

> +  *place &= insmask;
> +  *place |= grub_cpu_to_le32 (val) & ~insmask;
> +}
> +
>  void grub_loongarch64_b26 (grub_uint32_t *place, grub_int64_t offset)
>  {
>    grub_uint32_t val;
>    const grub_uint32_t insmask = grub_cpu_to_le32_compile_time (0xfc000000);
>
> -  grub_dprintf ("dl", "  reloc_xxxx64 %p %c= 0x%llx\n",
> +  grub_dprintf ("dl", "  reloc_b26 %p %c= 0x%llx\n",
>               place, offset > 0 ? '+' : '-',
>               offset < 0 ? (long long) -(unsigned long long) offset : offset);

Daniel