arch/arm/lib/relocate.S

/*
 *  relocate - common relocation function for ARM U-Boot
 *
 *  Copyright (c) 2013  Albert ARIBAUD <albert.u.boot@aribaud.net>
 *
 * SPDX-License-Identifier:	GPL-2.0+
 */

#include <linux/linkage.h>

/*
 * void relocate_code(addr_moni)
 *
 * This function relocates the monitor code.
 *
 * NOTE:
 * To prevent the code below from containing references with an R_ARM_ABS32
 * relocation record type, we never refer to linker-defined symbols directly.
 * Instead, we declare literals which contain their relative location with
 * respect to relocate_code, and at run time, add relocate_code back to them.
 */

ENTRY(relocate_code)
	ldr	r1, =__image_copy_start	/* r1 <- SRC &__image_copy_start */
	subs	r4, r0, r1		/* r4 <- relocation offset */
	beq	relocate_done		/* skip relocation */
	ldr	r2, =__image_copy_end	/* r2 <- SRC &__image_copy_end */

copy_loop:
	ldmia	r1!, {r10-r11}		/* copy from source address [r1]    */
	stmia	r0!, {r10-r11}		/* copy to   target address [r0]    */
	cmp	r1, r2			/* until source end address [r2]    */
	blo	copy_loop

	/*
	 * fix .rel.dyn relocations
	 */
	ldr	r2, =__rel_dyn_start	/* r2 <- SRC &__rel_dyn_start */
	ldr	r3, =__rel_dyn_end	/* r3 <- SRC &__rel_dyn_end */
fixloop:
	ldmia	r2!, {r0-r1}		/* (r0,r1) <- (SRC location,fixup) */
	and	r1, r1, #0xff
	cmp	r1, #23			/* relative fixup? */
	bne	fixnext

	/* relative fix: increase location by offset */
	add	r0, r0, r4
	ldr	r1, [r0]
	add	r1, r1, r4
	str	r1, [r0]
fixnext:
	cmp	r2, r3
	blo	fixloop

relocate_done:

#ifdef __XSCALE__
	/*
	 * On xscale, icache must be invalidated and write buffers drained,
	 * even with cache disabled - 4.2.7 of xscale core developer's manual
	 */
	mcr	p15, 0, r0, c7, c7, 0	/* invalidate icache */
	mcr	p15, 0, r0, c7, c10, 4	/* drain write buffer */
#endif

	/* ARMv4- don't know bx lr but the assembler fails to see that */

#ifdef __ARM_ARCH_4__
        mov        pc, lr
#else
        bx        lr
#endif

ENDPROC(relocate_code)