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

Darius Augulis
2010-10-24T20:08:51Z

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
/* 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*) }
}