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Commit 26e5ca93 authored by Dave Martin's avatar Dave Martin Committed by Russell King
Browse files

ARM: 6503/1: Thumb-2: Restore sensible zImage header layout for CONFIG_THUMB2_KERNEL 



The code which makes up the zImage header intends to leave a
32-byte gap followed by a branch to the real entry point, a magic
number, and a word containing the absolute entry point address.

This gets messed up with with CONFIG_THUMB2_KERNEL, because the
size of the initial padding NOPs changes.

Instead, the header can be made fully compatible by restoring it to
ARM.

In the Thumb-2 case, we can replace the initial NOPs with a
sequence which switches to Thumb and jumps to the real entry point.

As a consequence, the zImage entry point is now always ARM, so no
special magic is needed any more for the uImage rules in the
Thumb-2 case.

Signed-off-by: default avatarDave Martin <dave.martin@linaro.org>
Acked-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Acked-by: default avatarNicolas Pitre <nicolas.pitre@linaro.org>
Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent bfa64c4a

arch/arm/boot/Makefile

+0 −5
Original line number Original line Diff line number Diff line
@@ -70,12 +70,7 @@ else 
$(obj)/uImage: LOADADDR=$(ZRELADDR)

$(obj)/uImage: LOADADDR=$(ZRELADDR)

endif

endif





ifeq ($(CONFIG_THUMB2_KERNEL),y)

# Set bit 0 to 1 so that "mov pc, rx" switches to Thumb-2 mode

$(obj)/uImage: STARTADDR=$(shell echo $(LOADADDR) | sed -e "s/.$$/1/")

else

$(obj)/uImage: STARTADDR=$(LOADADDR)

$(obj)/uImage: STARTADDR=$(LOADADDR)

endif





$(obj)/uImage:	$(obj)/zImage FORCE

$(obj)/uImage:	$(obj)/zImage FORCE

	$(call if_changed,uimage)

	$(call if_changed,uimage)

arch/arm/boot/compressed/head.S

+6 −1
Original line number Original line Diff line number Diff line
@@ -125,9 +125,13 @@ wait: mrc p14, 0, pc, c0, c1, 0 
 * sort out different calling conventions

 * sort out different calling conventions

 */

 */

		.align

		.align

		.arm				@ Always enter in ARM state

start:

start:

		.type	start,#function

		.type	start,#function

		.rept	8

 THUMB(		adr	r12, BSYM(1f)	)

 THUMB(		bx	r12		)

 THUMB(		.rept	6		)

 ARM(		.rept	8		)

		mov	r0, r0

		mov	r0, r0

		.endr

		.endr
@@ -135,6 +139,7 @@ start: 
		.word	0x016f2818		@ Magic numbers to help the loader

		.word	0x016f2818		@ Magic numbers to help the loader

		.word	start			@ absolute load/run zImage address

		.word	start			@ absolute load/run zImage address

		.word	_edata			@ zImage end address

		.word	_edata			@ zImage end address

 THUMB(		.thumb			)

1:		mov	r7, r1			@ save architecture ID

1:		mov	r7, r1			@ save architecture ID

		mov	r8, r2			@ save atags pointer

		mov	r8, r2			@ save atags pointer