[U-Boot] [PATCH v2 33/47] x86: Add relocation and link script for a 64-bit EFI application

[Bin Meng]

On Fri, Jul 31, 2015 at 11:31 PM, Simon Glass <sjg at chromium.org> wrote:
> Add a linker script and relocation code for building 64-bit EFI
> applications. This can be used for the EFI stub.
>
> Signed-off-by: Simon Glass <sjg at chromium.org>
> Improvements to how the payload is built:
> Signed-off-by: Bin Meng <bmeng.cn at gmail.com>
> ---
>
> Changes in v2:
> - Add a comment as to why .hash has to be first in the linker script
> - Change 'link script' to 'linker script'
> - Drop . = 0x0;
> - Fix reference to elf_ia32_efi instead of elf_x86_64_efi
> - Merge in Bin's implementation of adding a U-Boot payload with objcopy
> - Remove KEEP in the EFI linker script since garbage collection is not enabled
> - Rename ImageBase to image_base
> - Update based on the elf.h changes
>
>  arch/x86/cpu/efi/elf_x86_64_efi.lds | 83 +++++++++++++++++++++++++++++++++++++
>  arch/x86/lib/efi/reloc_x86_64.c     | 66 +++++++++++++++++++++++++++++
>  2 files changed, 149 insertions(+)
>  create mode 100644 arch/x86/cpu/efi/elf_x86_64_efi.lds
>  create mode 100644 arch/x86/lib/efi/reloc_x86_64.c
>
> diff --git a/arch/x86/cpu/efi/elf_x86_64_efi.lds b/arch/x86/cpu/efi/elf_x86_64_efi.lds
> new file mode 100644
> index 0000000..667fbe2
> --- /dev/null
> +++ b/arch/x86/cpu/efi/elf_x86_64_efi.lds
> @@ -0,0 +1,83 @@
> +/*
> + * U-Boot EFI linker script
> + *
> + * SPDX-License-Identifier:    bsd-2-clause
> + *
> + * Modified from usr/lib32/elf_x86_64_efi.lds in gnu-efi
> + */
> +
> +#include <config.h>
> +
> +OUTPUT_FORMAT("elf64-x86-64", "elf64-x86-64", "elf64-x86-64")
> +OUTPUT_ARCH(i386:x86-64)
> +ENTRY(_start)
> +SECTIONS
> +{
> +       image_base = .;
> +       .hash : { *(.hash) }    /* this MUST come first, EFI expects it */
> +       . = ALIGN(4096);
> +       .eh_frame : {
> +               *(.eh_frame)
> +       }
> +
> +       . = ALIGN(4096);
> +
> +       .text : {
> +               *(.text)
> +               *(.text.*)
> +               *(.gnu.linkonce.t.*)
> +       }
> +
> +       . = ALIGN(4096);
> +
> +       .reloc : {
> +               *(.reloc)
> +       }
> +
> +       . = ALIGN(4096);
> +
> +       .data : {
> +               *(.rodata*)
> +               *(.got.plt)
> +               *(.got)
> +               *(.data*)
> +               *(.sdata)
> +               /* the EFI loader doesn't seem to like a .bss section, so we stick
> +                * it all into .data: */
> +               *(.sbss)
> +               *(.scommon)
> +               *(.dynbss)
> +               *(.bss)
> +               *(COMMON)
> +               *(.rel.local)
> +
> +               /* U-Boot lists and device tree */
> +               . = ALIGN(8);
> +               *(SORT(.u_boot_list*));
> +               . = ALIGN(8);
> +               *(.dtb*);
> +       }
> +
> +       . = ALIGN(4096);
> +       .dynamic : { *(.dynamic) }
> +       . = ALIGN(4096);
> +
> +       .rela : {
> +               *(.rela.data*)
> +               *(.rela.got)
> +               *(.rela.stab)
> +       }
> +
> +       . = ALIGN(4096);
> +       .dynsym : { *(.dynsym) }
> +       . = ALIGN(4096);
> +       .dynstr : { *(.dynstr) }
> +       . = ALIGN(4096);
> +       .ignored.reloc : {
> +               *(.rela.reloc)
> +               *(.eh_frame)
> +               *(.note.GNU-stack)
> +       }
> +
> +       .comment 0 : { *(.comment) }
> +}
> diff --git a/arch/x86/lib/efi/reloc_x86_64.c b/arch/x86/lib/efi/reloc_x86_64.c
> new file mode 100644
> index 0000000..5f71f2a
> --- /dev/null
> +++ b/arch/x86/lib/efi/reloc_x86_64.c
> @@ -0,0 +1,66 @@
> +/*
> + * reloc_x86_64.c - position independent x86_64 ELF shared object relocator
> + * Copyright (C) 1999 Hewlett-Packard Co.
> + * Contributed by David Mosberger <davidm at hpl.hp.com>.
> + * Copyright (C) 2005 Intel Co.
> + * Contributed by Fenghua Yu <fenghua.yu at intel.com>.
> + *
> + * All rights reserved.
> + *
> + * SPDX-License-Identifier:    BSD-3-Clause
> + */
> +
> +#include <common.h>
> +#include <efi.h>
> +#include <elf.h>
> +#include <asm/elf.h>
> +
> +efi_status_t _relocate(long ldbase, Elf64_Dyn *dyn, efi_handle_t image,
> +                      struct efi_system_table *systab)
> +{
> +       long relsz = 0, relent = 0;
> +       Elf64_Rel *rel = 0;
> +       unsigned long *addr;
> +       int i;
> +
> +       for (i = 0; dyn[i].d_tag != DT_NULL; ++i) {
> +               switch (dyn[i].d_tag) {
> +               case DT_RELA:
> +                       rel = (Elf64_Rel *)
> +                               ((unsigned long)dyn[i].d_un.d_ptr + ldbase);
> +                       break;
> +               case DT_RELASZ:
> +                       relsz = dyn[i].d_un.d_val;
> +                       break;
> +               case DT_RELAENT:
> +                       relent = dyn[i].d_un.d_val;
> +                       break;
> +               default:
> +                       break;
> +               }
> +       }
> +
> +       if (!rel && relent == 0)
> +               return EFI_SUCCESS;
> +
> +       if (!rel || relent == 0)
> +               return EFI_LOAD_ERROR;
> +
> +       while (relsz > 0) {
> +               /* apply the relocs */
> +               switch (ELF64_R_TYPE(rel->r_info)) {
> +               case R_X86_64_NONE:
> +                       break;
> +               case R_X86_64_RELATIVE:
> +                       addr = (unsigned long *)(ldbase + rel->r_offset);
> +                       *addr += ldbase;
> +                       break;
> +               default:
> +                       break;
> +               }
> +               rel = (Elf64_Rel *)((char *)rel + relent);
> +               relsz -= relent;
> +       }
> +
> +       return EFI_SUCCESS;
> +}
> --

Reviewed-by: Bin Meng <bmeng.cn at gmail.com>