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| 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 14:44:26 +0100 |
| commit | 26e5ca93dda9425f8ff78ccb2f9b193328087e45 (patch) | |
| tree | fae95715e23c176c804766612b5d2702c236fcf0 /arch/arm/boot/compressed/head.S | |
| parent | ARM: 6502/1: Thumb-2: Fix CONFIG_THUMB2_KERNEL breakage in compressed/head.S (diff) | |
| download | linux-26e5ca93dda9425f8ff78ccb2f9b193328087e45.tar.xz linux-26e5ca93dda9425f8ff78ccb2f9b193328087e45.zip | |
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>
Diffstat (limited to 'arch/arm/boot/compressed/head.S')
| -rw-r--r-- | arch/arm/boot/compressed/head.S | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/arch/arm/boot/compressed/head.S b/arch/arm/boot/compressed/head.S index be97e0832d73..7193884ed8b0 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 |