diff options
| author | Dave Martin <dave.martin@linaro.org> | 2010-11-29 19:43:27 +0100 |
|---|---|---|
| committer | Russell King <rmk+kernel@arm.linux.org.uk> | 2010-11-30 13:44:26 +0000 |
| commit | 26e5ca93dda9425f8ff78ccb2f9b193328087e45 (patch) | |
| tree | fae95715e23c176c804766612b5d2702c236fcf0 | |
| parent | bfa64c4ab1235b732542f11f4e0005e1774f779a (diff) | |
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: Dave Martin <dave.martin@linaro.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
| -rw-r--r-- | arch/arm/boot/Makefile | 5 | ||||
| -rw-r--r-- | arch/arm/boot/compressed/head.S | 7 |
2 files changed, 6 insertions, 6 deletions
diff --git a/arch/arm/boot/Makefile b/arch/arm/boot/Makefile index 4a590f4113e..4d26f2c52a7 100644 --- a/arch/arm/boot/Makefile +++ b/arch/arm/boot/Makefile @@ -70,12 +70,7 @@ else $(obj)/uImage: LOADADDR=$(ZRELADDR) 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) -endif $(obj)/uImage: $(obj)/zImage FORCE $(call if_changed,uimage) diff --git a/arch/arm/boot/compressed/head.S b/arch/arm/boot/compressed/head.S index be97e0832d7..7193884ed8b 100644 --- a/arch/arm/boot/compressed/head.S +++ b/arch/arm/boot/compressed/head.S @@ -125,9 +125,13 @@ wait: mrc p14, 0, pc, c0, c1, 0 * sort out different calling conventions */ .align + .arm @ Always enter in ARM state start: .type start,#function - .rept 8 + THUMB( adr r12, BSYM(1f) ) + THUMB( bx r12 ) + THUMB( .rept 6 ) + ARM( .rept 8 ) mov r0, r0 .endr @@ -135,6 +139,7 @@ start: .word 0x016f2818 @ Magic numbers to help the loader .word start @ absolute load/run zImage address .word _edata @ zImage end address + THUMB( .thumb ) 1: mov r7, r1 @ save architecture ID mov r8, r2 @ save atags pointer |