[U-Boot] [PATCH] arm1176: fix relocation

Darius Augulis
2010-10-24T20:22:43Z

On 10/24/2010 11:08 PM, Darius Augulis wrote:
> Fix relocation code for arm1176, do it like other ARM
> CPU's are doing.
> Tested only with CONFIG_SKIP_RELOCATE_UBOOT defined
> and using nand_spl (booting from nand). Test done on
> s3c6410 based board (not yet supported in main line).
>
> Signed-off-by: Darius Augulis<augulis.darius@gmail.com>
> ---
> arch/arm/cpu/arm1176/start.S | 139 +++++++++++++++++++++++----------------
> arch/arm/cpu/arm1176/u-boot.lds | 15 +++-
> 2 files changed, 94 insertions(+), 60 deletions(-)
>
> diff --git a/arch/arm/cpu/arm1176/start.S b/arch/arm/cpu/arm1176/start.S
> index 24e5bf4..0d733f7 100644
> --- a/arch/arm/cpu/arm1176/start.S
> +++ b/arch/arm/cpu/arm1176/start.S
> @@ -115,44 +115,52 @@ _armboot_start:
>
> /*
> * These are defined in the board-specific linker script.
> + * Subtracting _start from them lets the linker put their
> + * relative position in the executable instead of leaving
> + * them null.
> */
> -.globl _bss_start
> -_bss_start:
> - .word __bss_start
>
> -.globl _bss_end
> -_bss_end:
> - .word _end
> +.globl _bss_start_ofs
> +_bss_start_ofs:
> + .word __bss_start - _start
>
> -#if !defined(CONFIG_SYS_ARM_WITHOUT_RELOC)
> -/* IRQ stack memory (calculated at run-time) + 8 bytes */
> -.globl IRQ_STACK_START_IN
> -IRQ_STACK_START_IN:
> - .word 0x0badc0de
> +.globl _bss_end_ofs
> +_bss_end_ofs:
> + .word _end - _start
> +
> +.globl _datarel_start_ofs
> +_datarel_start_ofs:
> + .word __datarel_start - _start
>
> -.globl _datarel_start
> -_datarel_start:
> - .word __datarel_start
> +.globl _datarelrolocal_start_ofs
> +_datarelrolocal_start_ofs:
> + .word __datarelrolocal_start - _start
>
> -.globl _datarelrolocal_start
> -_datarelrolocal_start:
> - .word __datarelrolocal_start
> +.globl _datarellocal_start_ofs
> +_datarellocal_start_ofs:
> + .word __datarellocal_start - _start
>
> -.globl _datarellocal_start
> -_datarellocal_start:
> - .word __datarellocal_start
> +.globl _datarelro_start_ofs
> +_datarelro_start_ofs:
> + .word __datarelro_start - _start
>
> -.globl _datarelro_start
> -_datarelro_start:
> - .word __datarelro_start
> +.globl _rel_dyn_start_ofs
> +_rel_dyn_start_ofs:
> + .word __rel_dyn_start - _start
>
> -.globl _got_start
> -_got_start:
> - .word __got_start
> +.globl _rel_dyn_end_ofs
> +_rel_dyn_end_ofs:
> + .word __rel_dyn_end - _start
>
> -.globl _got_end
> -_got_end:
> - .word __got_end
> +.globl _dynsym_start_ofs
> +_dynsym_start_ofs:
> + .word __dynsym_start - _start
> +
> +#if !defined(CONFIG_SYS_ARM_WITHOUT_RELOC)
> +/* IRQ stack memory (calculated at run-time) + 8 bytes */
> +.globl IRQ_STACK_START_IN
> +IRQ_STACK_START_IN:
> + .word 0x0badc0de
>
> /*
> * the actual reset code
> @@ -274,9 +282,8 @@ stack_setup:
>
> adr r0, _start
> ldr r2, _TEXT_BASE
> - ldr r3, _bss_start
> - sub r2, r3, r2 /* r2<- size of armboot */
> - add r2, r0, r2 /* r2<- source end address */
> + ldr r3, _bss_start_ofs
> + add r2, r0, r3 /* r2<- source end address */
> cmp r0, r6
> beq clear_bss
>
> @@ -288,24 +295,44 @@ copy_loop:
> blo copy_loop
>
> #ifndef CONFIG_PRELOADER
> - /* fix got entries */
> - ldr r1, _TEXT_BASE /* Text base */
> - mov r0, r7 /* reloc addr */
> - ldr r2, _got_start /* addr in Flash */
> - ldr r3, _got_end /* addr in Flash */
> - sub r3, r3, r1
> - add r3, r3, r0
> - sub r2, r2, r1
> - add r2, r2, r0
> -
> + /*
> + * fix .rel.dyn relocations
> + */
> + ldr r0, _TEXT_BASE /* r0<- Text base */
> + sub r9, r7, r0 /* r9<- relocation offset */
> + ldr r10, _dynsym_start_ofs /* r10<- sym table ofs */
> + add r10, r10, r0 /* r10<- sym table in FLASH */
> + ldr r2, _rel_dyn_start_ofs /* r2<- rel dyn start ofs */
> + add r2, r2, r0 /* r2<- rel dyn start in FLASH */
> + ldr r3, _rel_dyn_end_ofs /* r3<- rel dyn end ofs */
> + add r3, r3, r0 /* r3<- rel dyn end in FLASH */
> fixloop:
> - ldr r4, [r2]
> - sub r4, r4, r1
> - add r4, r4, r0
> - str r4, [r2]
> - add r2, r2, #4
> + ldr r0, [r2] /* r0<- location to fix up, IN FLASH! */
> + add r0, r9 /* r0<- location to fix up in RAM */
> + ldr r1, [r2, #4]
> + and r8, r1, #0xff
> + cmp r8, #23 /* relative fixup? */
> + beq fixrel
> + cmp r8, #2 /* absolute fixup? */
> + beq fixabs
> + /* ignore unknown type of fixup */
> + b fixnext
> +fixabs:
> + /* absolute fix: set location to (offset) symbol value */
> + mov r1, r1, LSR #4 /* r1<- symbol index in .dynsym */
> + add r1, r10, r1 /* r1<- address of symbol in table */
> + ldr r1, [r1, #4] /* r1<- symbol value */
> + add r1, r9 /* r1<- relocated sym addr */
> + b fixnext
> +fixrel:
> + /* relative fix: increase location by offset */
> + ldr r1, [r0]
> + add r1, r1, r9
> +fixnext:
> + str r1, [r0]
> + add r2, r2, #8 /* each rel.dyn entry is 8 bytes */
> cmp r2, r3
> - bne fixloop
> + ble fixloop
> #endif
> #endif /* #ifndef CONFIG_SKIP_RELOCATE_UBOOT */
>
> @@ -349,13 +376,11 @@ skip_hw_init:
>
> clear_bss:
> #ifndef CONFIG_PRELOADER
> - ldr r0, _bss_start
> - ldr r1, _bss_end
> + ldr r0, _bss_start_ofs
> + ldr r1, _bss_end_ofs
> ldr r3, _TEXT_BASE /* Text base */
> mov r4, r7 /* reloc addr */
> - sub r0, r0, r3
> add r0, r0, r4
> - sub r1, r1, r3
> add r1, r1, r4
> mov r2, #0x00000000 /* clear */
>
> @@ -377,10 +402,9 @@ clbss_l:str r2, [r0] /* clear loop... */
>
> _nand_boot: .word nand_boot
> #else
> - ldr r0, _TEXT_BASE
> - ldr r2, _board_init_r
> - sub r2, r2, r0
> - add r2, r2, r7 /* position from board_init_r in RAM */
> + ldr r0, _board_init_r_ofs
> + adr r1, _start
> + add r2, r0, r1

RFC:
I've observed that other ARM CPU's are adding r9 to lr here (add lr,
r0, r9). Even though r9 is not pre-loaded with any value in case
CONFIG_SKIP_RELOCATE_UBOOT is defined. Is it bug or not?
Maybe it's not tested without CONFIG_SKIP_RELOCATE_UBOOT?
I've removed this line because uboot stops booting if it's there.
Any comments about it?

> /* setup parameters for board_init_r */
> mov r0, r5 /* gd_t */
> mov r1, r7 /* dest_addr */
> @@ -388,7 +412,8 @@ _nand_boot: .word nand_boot
> mov lr, r2
> mov pc, lr
>
> -_board_init_r: .word board_init_r
> +_board_init_r_ofs:
> + .word board_init_r - _start
> #endif
>
> #else /* #if !defined(CONFIG_SYS_ARM_WITHOUT_RELOC) */
> diff --git a/arch/arm/cpu/arm1176/u-boot.lds b/arch/arm/cpu/arm1176/u-boot.lds
> index fa640ee..d9ed954 100644
> --- a/arch/arm/cpu/arm1176/u-boot.lds
> +++ b/arch/arm/cpu/arm1176/u-boot.lds
> @@ -51,11 +51,14 @@ SECTIONS
> *(.data.rel.ro)
> }
>
> - __got_start = .;
> . = ALIGN(4);
> - .got : { *(.got) }
> + __rel_dyn_start = .;
> + .rel.dyn : { *(.rel.dyn) }
> + __rel_dyn_end = .;
> +
> + __dynsym_start = .;
> + .dynsym : { *(.dynsym) }
>
> - __got_end = .;
> . = .;
> __u_boot_cmd_start = .;
> .u_boot_cmd : { *(.u_boot_cmd) }
> @@ -65,4 +68,10 @@ SECTIONS
> __bss_start = .;
> .bss (NOLOAD) : { *(.bss) . = ALIGN(4); }
> _end = .;
> +
> + /DISCARD/ : { *(.dynstr*) }
> + /DISCARD/ : { *(.dynamic*) }
> + /DISCARD/ : { *(.plt*) }
> + /DISCARD/ : { *(.interp*) }
> + /DISCARD/ : { *(.gnu*) }
> }