arm: implement ELF relocations
ELF relocation tables generated with linker option -pie can
be used to fixup code and data in a single loop at relocation,
removing the need for manual fixups anywhere else in the code.
Signed-off-by: Albert Aribaud <albert.aribaud@free.fr>
diff --git a/arch/arm/config.mk b/arch/arm/config.mk
index 6923f6d..0be47d3 100644
--- a/arch/arm/config.mk
+++ b/arch/arm/config.mk
@@ -33,11 +33,6 @@
endif
endif
-ifndef CONFIG_SYS_ARM_WITHOUT_RELOC
-# needed for relocation
-PLATFORM_RELFLAGS += -fPIC
-endif
-
ifdef CONFIG_SYS_ARM_WITHOUT_RELOC
PLATFORM_CPPFLAGS += -DCONFIG_SYS_ARM_WITHOUT_RELOC
endif
@@ -72,3 +67,8 @@
endif
endif
LDSCRIPT := $(SRCTREE)/$(CPUDIR)/u-boot.lds
+
+ifndef CONFIG_SYS_ARM_WITHOUT_RELOC
+# needed for relocation
+PLATFORM_LDFLAGS += -pie
+endif
diff --git a/arch/arm/cpu/arm926ejs/start.S b/arch/arm/cpu/arm926ejs/start.S
index a960689..49ca839 100644
--- a/arch/arm/cpu/arm926ejs/start.S
+++ b/arch/arm/cpu/arm926ejs/start.S
@@ -10,6 +10,7 @@
* Copyright (c) 2002 Gary Jennejohn <garyj@denx.de>
* Copyright (c) 2003 Richard Woodruff <r-woodruff2@ti.com>
* Copyright (c) 2003 Kshitij <kshitij@ti.com>
+ * Copyright (c) 2010 Albert Aribaud <albert.aribaud@free.fr>
*
* See file CREDITS for list of people who contributed to this
* project.
@@ -118,22 +119,19 @@
_TEXT_BASE:
.word TEXT_BASE
-#if defined(CONFIG_SYS_ARM_WITHOUT_RELOC)
-.globl _armboot_start
-_armboot_start:
- .word _start
-#endif
-
/*
* 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 _end - _start
#ifdef CONFIG_USE_IRQ
/* IRQ stack memory (calculated at run-time) */
@@ -153,30 +151,6 @@
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 reset code
*/
@@ -226,9 +200,8 @@
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
@@ -240,36 +213,54 @@
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
+ blo fixloop
#endif
#endif /* #ifndef CONFIG_SKIP_RELOCATE_UBOOT */
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 */
@@ -287,24 +278,33 @@
* initialization, now running from RAM.
*/
#ifdef CONFIG_NAND_SPL
- ldr pc, _nand_boot
-
-_nand_boot: .word nand_boot
+ ldr r0, _nand_boot_ofs
+ adr r1, _start
+ add pc, r0, r1
+_nand_boot_ofs
+ : .word nand_boot - _start
#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 r0, r0, r1
+ add lr, r0, r9
/* 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
+
#else /* #if !defined(CONFIG_SYS_ARM_WITHOUT_RELOC) */
/*
* the actual reset code
@@ -333,10 +333,8 @@
ldr r1, _TEXT_BASE /* test if we run from flash or RAM */
cmp r0, r1 /* don't reloc during debug */
beq stack_setup
- ldr r2, _armboot_start
- 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 /* r3 <- _bss_start - _start */
+ add r2, r0, r3 /* r2 <- source end address */
copy_loop:
ldmia r0!, {r3-r10} /* copy from source address [r0] */
@@ -360,8 +358,11 @@
bic sp, sp, #7 /* 8-byte alignment for ABI compliance */
clear_bss:
- ldr r0, _bss_start /* find start of bss segment */
- ldr r1, _bss_end /* stop here */
+ adr r2, _start
+ ldr r0, _bss_start_ofs /* find start of bss segment */
+ add r0, r0, r2
+ ldr r1, _bss_end_ofs /* stop here */
+ add r1, r1, r2
mov r2, #0x00000000 /* clear */
#ifndef CONFIG_PRELOADER
@@ -374,13 +375,16 @@
bl red_LED_on
#endif /* CONFIG_PRELOADER */
- ldr pc, _start_armboot
+ ldr r0, _start_armboot_ofs
+ adr r1, _start
+ add r0, r0, r1
+ ldr pc, r0
-_start_armboot:
+_start_armboot_ofs:
#ifdef CONFIG_NAND_SPL
- .word nand_boot
+ .word nand_boot - _start
#else
- .word start_armboot
+ .word start_armboot - _start
#endif /* CONFIG_NAND_SPL */
#endif /* #if !defined(CONFIG_SYS_ARM_WITHOUT_RELOC) */
@@ -469,7 +473,7 @@
sub sp, sp, #S_FRAME_SIZE
stmia sp, {r0 - r12} @ Save user registers (now in svc mode) r0-r12
#if defined(CONFIG_SYS_ARM_WITHOUT_RELOC)
- ldr r2, _armboot_start
+ adr r2, _start
sub r2, r2, #(CONFIG_STACKSIZE+CONFIG_SYS_MALLOC_LEN)
sub r2, r2, #(CONFIG_SYS_GBL_DATA_SIZE+8) @ set base 2 words into abort stack
#else
@@ -507,7 +511,7 @@
.macro get_bad_stack
#if defined(CONFIG_SYS_ARM_WITHOUT_RELOC)
- ldr r13, _armboot_start @ setup our mode stack
+ adr r13, _start @ setup our mode stack
sub r13, r13, #(CONFIG_STACKSIZE+CONFIG_SYS_MALLOC_LEN)
sub r13, r13, #(CONFIG_SYS_GBL_DATA_SIZE+8) @ reserved a couple spots in abort stack
#else
diff --git a/arch/arm/cpu/arm926ejs/u-boot.lds b/arch/arm/cpu/arm926ejs/u-boot.lds
index 02eb8ca..72f45f8 100644
--- a/arch/arm/cpu/arm926ejs/u-boot.lds
+++ b/arch/arm/cpu/arm926ejs/u-boot.lds
@@ -41,21 +41,19 @@
. = 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 = .;
+ __rel_dyn_start = .;
+ .rel.dyn : { *(.rel.dyn) }
+ __rel_dyn_end = .;
+
+ __dynsym_start = .;
+ .dynsym : { *(.dynsym) }
+
+ . = ALIGN(4);
+
. = .;
__u_boot_cmd_start = .;
.u_boot_cmd : { *(.u_boot_cmd) }
@@ -65,4 +63,10 @@
__bss_start = .;
.bss (NOLOAD) : { *(.bss) . = ALIGN(4); }
_end = .;
+
+ /DISCARD/ : { *(.dynstr*) }
+ /DISCARD/ : { *(.dynamic*) }
+ /DISCARD/ : { *(.plt*) }
+ /DISCARD/ : { *(.interp*) }
+ /DISCARD/ : { *(.gnu*) }
}
diff --git a/arch/arm/include/asm/config.h b/arch/arm/include/asm/config.h
index 4e8dfd7..8d3eb10 100644
--- a/arch/arm/include/asm/config.h
+++ b/arch/arm/include/asm/config.h
@@ -21,8 +21,6 @@
#ifndef _ASM_CONFIG_H_
#define _ASM_CONFIG_H_
-#if defined(CONFIG_SYS_ARM_WITHOUT_RELOC)
/* Relocation to SDRAM works on all ARM boards */
#define CONFIG_RELOC_FIXUP_WORKS
#endif
-#endif
diff --git a/arch/arm/include/asm/u-boot-arm.h b/arch/arm/include/asm/u-boot-arm.h
index faf800a..4ac4f61 100644
--- a/arch/arm/include/asm/u-boot-arm.h
+++ b/arch/arm/include/asm/u-boot-arm.h
@@ -30,18 +30,18 @@
#define _U_BOOT_ARM_H_ 1
/* for the following variables, see start.S */
-extern ulong _bss_start; /* code + data end == BSS start */
-extern ulong _bss_end; /* BSS end */
+extern ulong _bss_start_ofs; /* BSS start relative to _start */
+extern ulong _bss_end_ofs; /* BSS end relative to _start */
extern ulong IRQ_STACK_START; /* top of IRQ stack */
extern ulong FIQ_STACK_START; /* top of FIQ stack */
#if defined(CONFIG_SYS_ARM_WITHOUT_RELOC)
-extern ulong _armboot_start; /* code start */
+extern ulong _armboot_start_ofs; /* code start */
#else
extern ulong _TEXT_BASE; /* code start */
-extern ulong _datarel_start;
-extern ulong _datarelrolocal_start;
-extern ulong _datarellocal_start;
-extern ulong _datarelro_start;
+extern ulong _datarel_start_ofs;
+extern ulong _datarelrolocal_start_ofs;
+extern ulong _datarellocal_start_ofs;
+extern ulong _datarelro_start_ofs;
extern ulong IRQ_STACK_START_IN; /* 8 bytes in IRQ stack */
#endif
diff --git a/arch/arm/lib/board.c b/arch/arm/lib/board.c
index 5f2dfd0..e411d93 100644
--- a/arch/arm/lib/board.c
+++ b/arch/arm/lib/board.c
@@ -147,7 +147,7 @@
#else
_armboot_start,
#endif
- _bss_start, _bss_end);
+ _bss_start_ofs+_TEXT_BASE, _bss_end_ofs+_TEXT_BASE);
#ifdef CONFIG_MODEM_SUPPORT
debug ("Modem Support enabled\n");
#endif
@@ -517,7 +517,7 @@
memset ((void*)gd, 0, sizeof (gd_t));
- gd->mon_len = _bss_end - _TEXT_BASE;
+ gd->mon_len = _bss_end_ofs;
for (init_fnc_ptr = init_sequence; *init_fnc_ptr; ++init_fnc_ptr) {
if ((*init_fnc_ptr)() != 0) {
@@ -679,6 +679,7 @@
*
************************************************************************
*/
+
void board_init_r (gd_t *id, ulong dest_addr)
{
char *s;
@@ -702,7 +703,7 @@
gd->flags |= GD_FLG_RELOC; /* tell others: relocation done */
- monitor_flash_len = _bss_start - _TEXT_BASE;
+ monitor_flash_len = _bss_start_ofs;
debug ("monitor flash len: %08lX\n", monitor_flash_len);
board_init(); /* Setup chipselects */
@@ -914,6 +915,7 @@
/* NOTREACHED - no way out of command loop except booting */
}
+
#endif /* defined(CONFIG_SYS_ARM_WITHOUT_RELOC) */
void hang (void)