[U-Boot,3/4] arm64: Non-manual relocation

This turns off CONFIG_NEEDS_MANUAL_RELOC and turns on -pie.

The bss part of the linker script is changed to be more like arm32,
as the previous arm64 approach was generating bad relocations (even
readelf didn't like them).

relocate_64.S is made to look more like relocate.S, and then changed to
support RELA style relocations rather than REL.

Signed-off-by: Scott Wood <scottwood@freescale.com>
---
 arch/arm/config.mk                |  2 --
 arch/arm/cpu/armv8/config.mk      |  1 -
 arch/arm/cpu/armv8/u-boot.lds     | 32 +++++++++++++++++++++++-------
 arch/arm/include/asm/config.h     |  5 -----
 arch/arm/lib/crt0_64.S            |  7 ++-----
 arch/arm/lib/relocate_64.S        | 41 ++++++++++++++++++++-------------------
 include/configs/vexpress_aemv8a.h |  3 +++
 7 files changed, 51 insertions(+), 40 deletions(-)

> This turns off CONFIG_NEEDS_MANUAL_RELOC and turns on -pie.
> 
> The bss part of the linker script is changed to be more like arm32,
> as the previous arm64 approach was generating bad relocations (even
> readelf didn't like them).
> 
> relocate_64.S is made to look more like relocate.S, and then changed to
> support RELA style relocations rather than REL.
> 
> Signed-off-by: Scott Wood <scottwood@freescale.com>
> ---
>  arch/arm/config.mk                |  2 --
>  arch/arm/cpu/armv8/config.mk      |  1 -
>  arch/arm/cpu/armv8/u-boot.lds     | 32 +++++++++++++++++++++++-------
>  arch/arm/include/asm/config.h     |  5 -----
>  arch/arm/lib/crt0_64.S            |  7 ++-----
>  arch/arm/lib/relocate_64.S        | 41 ++++++++++++++++++++-------------------
>  include/configs/vexpress_aemv8a.h |  3 +++
>  7 files changed, 51 insertions(+), 40 deletions(-)
> 
> diff --git a/arch/arm/config.mk b/arch/arm/config.mk
> index 95c07ad..96d2d88 100644
> --- a/arch/arm/config.mk
> +++ b/arch/arm/config.mk
> @@ -74,9 +74,7 @@ endif
>  endif
>  
>  # needed for relocation
> -ifndef CONFIG_ARM64
>  LDFLAGS_u-boot += -pie
> -endif
>  
>  #
>  # FIXME: binutils versions < 2.22 have a bug in the assembler where
> diff --git a/arch/arm/cpu/armv8/config.mk b/arch/arm/cpu/armv8/config.mk
> index 9f36d59..027a68c 100644
> --- a/arch/arm/cpu/armv8/config.mk
> +++ b/arch/arm/cpu/armv8/config.mk
> @@ -13,4 +13,3 @@ PLATFORM_NO_UNALIGNED := $(PF_NO_UNALIGNED)
>  PF_CPPFLAGS_ARMV8 := $(call cc-option, -march=armv8-a)
>  PLATFORM_CPPFLAGS += $(PF_CPPFLAGS_ARMV8)
>  PLATFORM_CPPFLAGS += $(PF_NO_UNALIGNED)
> -PLATFORM_CPPFLAGS += -fpic
> diff --git a/arch/arm/cpu/armv8/u-boot.lds b/arch/arm/cpu/armv8/u-boot.lds
> index 328d477..4c12222 100644
> --- a/arch/arm/cpu/armv8/u-boot.lds
> +++ b/arch/arm/cpu/armv8/u-boot.lds
> @@ -41,25 +41,43 @@ SECTIONS
>  	}
>  
>  	. = ALIGN(8);
> -	.reloc : {
> -		__rel_got_start = .;
> -		*(.got)
> -		__rel_got_end = .;
> -	}
>  
>  	.image_copy_end :
>  	{
>  		*(.__image_copy_end)
>  	}
>  
> +	. = ALIGN(8);
> +
> +	.rel_dyn_start :
> +	{
> +		*(.__rel_dyn_start)
> +	}
> +
> +	.rela.dyn : {
> +		*(.rela*)
> +	}
> +
> +	.rel_dyn_end :
> +	{
> +		*(.__rel_dyn_end)
> +	}
> +
>  	_end = .;
>  
>  	. = ALIGN(8);
> +
> +	.bss_start : {
> +		KEEP(*(.__bss_start));
> +	}
> +
>  	.bss : {
> -		__bss_start = .;
>  		*(.bss*)
>  		 . = ALIGN(8);
> -		__bss_end = .;
> +	}
> +
> +	.bss_end : {
> +		KEEP(*(.__bss_end));
>  	}
>  
>  	/DISCARD/ : { *(.dynsym) }
> diff --git a/arch/arm/include/asm/config.h b/arch/arm/include/asm/config.h
> index 0ee131d..de4d01e 100644
> --- a/arch/arm/include/asm/config.h
> +++ b/arch/arm/include/asm/config.h
> @@ -11,11 +11,6 @@
>  #define CONFIG_SYS_BOOT_RAMDISK_HIGH
>  
>  #ifdef CONFIG_ARM64
> -/*
> - * Currently, GOT is used to relocate u-boot and
> - * configuration CONFIG_NEEDS_MANUAL_RELOC is needed.
> - */
> -#define CONFIG_NEEDS_MANUAL_RELOC
>  #define CONFIG_PHYS_64BIT
>  #endif
>  
> diff --git a/arch/arm/lib/crt0_64.S b/arch/arm/lib/crt0_64.S
> index ddd46eb..7756396 100644
> --- a/arch/arm/lib/crt0_64.S
> +++ b/arch/arm/lib/crt0_64.S
> @@ -94,11 +94,8 @@ relocation_return:
>  /*
>   * Clear BSS section
>   */
> -	ldr	x9, [x18, #GD_RELOC_OFF]	/* x9 <- gd->reloc_off */
> -	ldr	x0, =__bss_start
> -	add	x0, x0, x9			/* x0 <- __bss_start in RAM */
> -	ldr	x1, =__bss_end
> -	add	x1, x1, x9			/* x1 <- __bss_end in RAM */
> +	ldr	x0, =__bss_start		/* this is auto-relocated! */
> +	ldr	x1, =__bss_end			/* this is auto-relocated! */
>  	mov	x2, #0
>  clear_loop:
>  	str	x2, [x0]
> diff --git a/arch/arm/lib/relocate_64.S b/arch/arm/lib/relocate_64.S
> index 29c3239..7fba9e2 100644
> --- a/arch/arm/lib/relocate_64.S
> +++ b/arch/arm/lib/relocate_64.S
> @@ -16,40 +16,41 @@
>   * void relocate_code (addr_moni)
>   *
>   * This function relocates the monitor code.
> - *
> - * NOTE:
> - * GOT is used and configuration CONFIG_NEEDS_MANUAL_RELOC is needed.
> + * x0 holds the destination address.
>   */
>  ENTRY(relocate_code)
>  	/*
>  	 * Copy u-boot from flash to RAM
>  	 */
> -	ldr	x1, =__image_copy_start	/* x1 <- copy source */
> -	cmp	x1, x0
> +	ldr	x1, =__image_copy_start	/* x1 <- SRC &__image_copy_start */
> +	subs	x9, x0, x1		/* x9 <- relocation offset */
>  	b.eq	relocate_done		/* skip relocation */
> -	mov	x2, x0			/* x2 <- copy destination */
> -	ldr	x3, =__image_copy_end	/* x3 <- source end address */
> +	ldr	x2, =__image_copy_end	/* x2 <- SRC &__image_copy_end */
>  
>  copy_loop:
>  	ldp	x10, x11, [x1], #16	/* copy from source address [x1] */
> -	stp	x10, x11, [x2], #16	/* copy to   target address [x2] */
> -	cmp	x1, x3			/* until source end address [x3] */
> +	stp	x10, x11, [x0], #16	/* copy to   target address [x0] */
> +	cmp	x1, x2			/* until source end address [x2] */
>  	b.lo	copy_loop
>  
>  	/*
> -	 * Fix .reloc relocations
> +	 * Fix .rela.dyn relocations
>  	 */
> -	ldr	x9, [x18, #GD_RELOC_OFF]/* x9 <- relocation offset */
> -	ldr	x1, =__rel_got_start	/* x1 <- rel got start ofs */
> -	add	x1, x1, x9		/* x1 <- rel got start in RAM */
> -	ldr	x2, =__rel_got_end	/* x2 <- rel got end ofs */
> -	add	x2, x2, x9		/* x2 <- rel got end in RAM */
> +	ldr	x2, =__rel_dyn_start	/* x2 <- SRC &__rel_dyn_start */
> +	ldr	x3, =__rel_dyn_end	/* x3 <- SRC &__rel_dyn_end */
>  fixloop:
> -	ldr	x10, [x1]
> -	add	x10, x10, x9		/* x10 <- address to be fixed up */
> -	str	x10, [x1]
> -	add	x1, x1, #8		/* each got entry is 8 bytes */
> -	cmp	x1, x2
> +	ldp	x0, x1, [x2], #16	/* (x0,x1) <- (SRC location, fixup) */
> +	ldr	x4, [x2], #8		/* x4 <- addend */
> +	and	x1, x1, #0xffffffff
> +	cmp	x1, #1027		/* relative fixup? */
> +	bne	fixnext
> +
> +	/* relative fix: store addend plus offset at dest location */
> +	add	x0, x0, x9
> +	add	x4, x4, x9
> +	str	x4, [x0]
> +fixnext:
> +	cmp	x2, x3
>  	b.lo	fixloop
>  
>  relocate_done:
> diff --git a/include/configs/vexpress_aemv8a.h b/include/configs/vexpress_aemv8a.h
> index 01c95f5..3932e00 100644
> --- a/include/configs/vexpress_aemv8a.h
> +++ b/include/configs/vexpress_aemv8a.h
> @@ -10,6 +10,9 @@
>  
>  #define DEBUG
>  
> +#define CONFIG_REMAKE_ELF
> +#define CONFIG_STATIC_RELA
> +
CONFIG_STATIC_RELA is always needed, How about remove this macro.

David,

On Sat, 2013-10-05 at 00:13 +0800, FengHua wrote:
> > diff --git a/include/configs/vexpress_aemv8a.h b/include/configs/vexpress_aemv8a.h
> > index 01c95f5..3932e00 100644
> > --- a/include/configs/vexpress_aemv8a.h
> > +++ b/include/configs/vexpress_aemv8a.h
> > @@ -10,6 +10,9 @@
> >  
> >  #define DEBUG
> >  
> > +#define CONFIG_REMAKE_ELF
> > +#define CONFIG_STATIC_RELA
> > +
> CONFIG_STATIC_RELA is always needed, How about remove this macro.

It's always needed for arm64, but not for all architectures.  I don't
want to just use CONFIG_ARM64 because in theory another arch could be
added that needs it.  Eventually this should be moved out of the board
config and into a file that defines general arm64 stuff.

-Scott