[U-Boot] [PATCH v3] arm920t: implement elf relocation

Andreas Bießmann
2010-11-03T23:29:28Z

This is mostly a copy of arm926ejs relocation and known to _not_ work
correctly a.t.m!

Signed-off-by: Andreas Bie?mann <andreas.devel@googlemail.com>
---
changes since v1:
- adopted linker script as in patch series v3 "arm926ejs: fix linker file for newer ld support"
* move rel.dyn and dynsym after bss
* overlay bss with rel.dyn
- double checked fixup loop in start.S
-> there is still an error in relocation fixup loop breaks the boot,
the board hangs after "relocation Offset is: 00f80000"

Dear Albert Aribaud,
can you please have a look for that?

changes since v2:
- add missed parts in "branch board_init_r"

Dear Albert Aribaud,
still not working, do you have any advice?

arch/arm/cpu/arm920t/start.S | 129 ++++++++++++++++++++-------------------
arch/arm/cpu/arm920t/u-boot.lds | 37 +++++++----
2 files changed, 89 insertions(+), 77 deletions(-)

diff --git a/arch/arm/cpu/arm920t/start.S b/arch/arm/cpu/arm920t/start.S
index d4edde7..c547181 100644
--- a/arch/arm/cpu/arm920t/start.S
+++ b/arch/arm/cpu/arm920t/start.S
@@ -77,14 +77,17 @@ _TEXT_BASE:

/*
* 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_start_ofs
+_bss_start_ofs:
+ .word __bss_start - _start

-.globl _bss_end
-_bss_end:
- .word _end
+.globl _bss_end_ofs
+_bss_end_ofs:
+ .word _bss_end - _start

#ifdef CONFIG_USE_IRQ
/* IRQ stack memory (calculated at run-time) */
@@ -103,30 +106,6 @@ FIQ_STACK_START:
IRQ_STACK_START_IN:
.word 0x0badc0de

-.globl _datarel_start
-_datarel_start:
- .word __datarel_start
-
-.globl _datarelrolocal_start
-_datarelrolocal_start:
- .word __datarelrolocal_start
-
-.globl _datarellocal_start
-_datarellocal_start:
- .word __datarellocal_start
-
-.globl _datarelro_start
-_datarelro_start:
- .word __datarelro_start
-
-.globl _got_start
-_got_start:
- .word __got_start
-
-.globl _got_end
-_got_end:
- .word __got_end
-
/*
* the actual start code
*/
@@ -164,7 +143,7 @@ copyex:
# define pWTCON 0x15300000
# define INTMSK 0x14400008 /* Interupt-Controller base addresses */
# define CLKDIVN 0x14800014 /* clock divisor register */
-#else
+# else
# define pWTCON 0x53000000
# define INTMSK 0x4A000008 /* Interupt-Controller base addresses */
# define INTSUBMSK 0x4A00001C
@@ -230,9 +209,8 @@ 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

@@ -243,35 +221,53 @@ 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 offset */
+ add r10, r10, r0 /* r10 <- sym table in FLASH */
+ ldr r2, _rel_dyn_start_ofs /* r2 <- rel dyn start offset */
+ add r2, r2, r0 /* r2 <- rel dyn start in FLASH */
+ ldr r3, _rel_dyn_end_ofs /* r3 <- rel dyn end offset */
+ 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, 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 (offste) 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 address */
+ 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
blo fixloop
#endif

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 */

@@ -289,24 +285,33 @@ clbss_l:str r2, [r0] /* clear loop... */
* initialization, now running from RAM.
*/
#ifdef CONFIG_NAND_SPL
- ldr pc, _nand_boot
+ ldr r0, _nand_boot_ofs
+ mov pc, r0

-_nand_boot: .word nand_boot
+_nand_boot_ofs:
+ .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 lr, r0, r1
+ add lr, lr, r9 /* position from board_init_r in RAM */
/* setup parameters for board_init_r */
mov r0, r5 /* gd_t */
mov r1, r7 /* dest_addr */
/* jump to it ... */
- mov lr, r2
mov pc, lr

-_board_init_r: .word board_init_r
+_board_init_r_ofs:
+ .word board_init_r - _start
#endif

+_rel_dyn_start_ofs:
+ .word __rel_dyn_start - _start
+_rel_dyn_end_ofs:
+ .word __rel_dyn_end - _start
+_dynsym_start_ofs:
+ .word __dynsym_start - _start
+
/*
*************************************************************************
*
@@ -317,8 +322,6 @@ _board_init_r: .word board_init_r
*
*************************************************************************
*/
-
-
#ifndef CONFIG_SKIP_LOWLEVEL_INIT
cpu_init_crit:
/*
diff --git a/arch/arm/cpu/arm920t/u-boot.lds b/arch/arm/cpu/arm920t/u-boot.lds
index 6985434..d647952 100644
--- a/arch/arm/cpu/arm920t/u-boot.lds
+++ b/arch/arm/cpu/arm920t/u-boot.lds
@@ -49,28 +49,37 @@ SECTIONS
. = ALIGN(4);
.data : {
*(.data)
- __datarel_start = .;
- *(.data.rel)
- __datarelrolocal_start = .;
- *(.data.rel.ro.local)
- __datarellocal_start = .;
- *(.data.rel.local)
- __datarelro_start = .;
- *(.data.rel.ro)
}

- __got_start = .;
. = ALIGN(4);
- .got : { *(.got) }

- __got_end = .;
. = .;
__u_boot_cmd_start = .;
.u_boot_cmd : { *(.u_boot_cmd) }
__u_boot_cmd_end = .;

. = ALIGN(4);
- __bss_start = .;
- .bss (NOLOAD) : { *(.bss) . = ALIGN(4); }
- _end = .;
+ .bss (NOLOAD) : {
+ __bss_start = .;
+ *(.bss)
+ . = ALIGN(4);
+ _bss_end = .;
+ }
+
+ .rel.dyn __bss_start (OVERLAY) : {
+ __rel_dyn_start = .;
+ *(.rel*)
+ __rel_dyn_end = .;
+ }
+
+ .dynsym : {
+ __dynsym_start = .;
+ *(.dynsym)
+ }
+
+ /DISCARD/ : { *(.dynstr*) }
+ /DISCARD/ : { *(.dynamic*) }
+ /DISCARD/ : { *(.plt*) }
+ /DISCARD/ : { *(.interp*) }
+ /DISCARD/ : { *(.gnu*) }
}
--
1.7.3.2