Re: [PATCH 1/1] MIPS: Ensure ELF appended dtb is relocated

From: Paul Burton
Date: Fri Mar 08 2019 - 14:02:43 EST


Hi Yasha,

On Fri, Mar 08, 2019 at 02:58:51PM +0200, Yasha Cherikovsky wrote:
> This fixes booting with the combination of CONFIG_RELOCATABLE=y
> and CONFIG_MIPS_ELF_APPENDED_DTB=y.
>
> Sections that appear after the relocation table are not relocated
> on system boot (except .bss, which has special handling).
>
> With CONFIG_MIPS_ELF_APPENDED_DTB, the dtb is part of the
> vmlinux ELF, so it must be relocated together with everything else.

Do you have any ideas how CONFIG_RELOCATABLE interacts with
CONFIG_MIPS_RAW_APPENDED_DTB? I'm wondering whether we should move both
variants of appended DTB to before .data.reloc, but haven't yet thought
it through.

Thanks,
Paul

> Fixes: 069fd766271d ("MIPS: Reserve space for relocation table")
> Signed-off-by: Yasha Cherikovsky <yasha.che3@xxxxxxxxx>
> Cc: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
> Cc: Paul Burton <paul.burton@xxxxxxxx>
> Cc: James Hogan <jhogan@xxxxxxxxxx>
> Cc: linux-mips@xxxxxxxxxxxxxx
> Cc: linux-kernel@xxxxxxxxxxxxxxx
> ---
> arch/mips/kernel/vmlinux.lds.S | 12 +++++++-----
> 1 file changed, 7 insertions(+), 5 deletions(-)
>
> diff --git a/arch/mips/kernel/vmlinux.lds.S b/arch/mips/kernel/vmlinux.lds.S
> index cb7e9ed7a453..33ee0d18fb0a 100644
> --- a/arch/mips/kernel/vmlinux.lds.S
> +++ b/arch/mips/kernel/vmlinux.lds.S
> @@ -140,6 +140,13 @@ SECTIONS
> PERCPU_SECTION(1 << CONFIG_MIPS_L1_CACHE_SHIFT)
> #endif
>
> +#ifdef CONFIG_MIPS_ELF_APPENDED_DTB
> + .appended_dtb : AT(ADDR(.appended_dtb) - LOAD_OFFSET) {
> + *(.appended_dtb)
> + KEEP(*(.appended_dtb))
> + }
> +#endif
> +
> #ifdef CONFIG_RELOCATABLE
> . = ALIGN(4);
>
> @@ -164,11 +171,6 @@ SECTIONS
> __appended_dtb = .;
> /* leave space for appended DTB */
> . += 0x100000;
> -#elif defined(CONFIG_MIPS_ELF_APPENDED_DTB)
> - .appended_dtb : AT(ADDR(.appended_dtb) - LOAD_OFFSET) {
> - *(.appended_dtb)
> - KEEP(*(.appended_dtb))
> - }
> #endif
> /*
> * Align to 64K in attempt to eliminate holes before the
> --
> 2.21.0
>