[U-Boot] [PATCH v3 1/2] armv8: Support loading 32-bit OS in AArch32 execution state

[York Sun]

On 05/26/2016 01:51 AM, Alison Wang wrote:
> To support loading a 32-bit OS, the execution state will change from
> AArch64 to AArch32 when jumping to kernel.
> 
> The architecture information will be got through checking FIT
> image, then U-Boot will load 32-bit OS or 64-bit OS automatically.
> 
> Signed-off-by: Ebony Zhu <ebony.zhu at nxp.com>
> Signed-off-by: Alison Wang <alison.wang at nxp.com>
> Signed-off-by: Chenhui Zhao <chenhui.zhao at nxp.com>
> ---
> Changes in v3:
> - Comments the functions and the arguments.
> - Rename the real parameters.
> - Use the macros instead of the magic values.
> - Remove the redundant codes.
> - Clean up all of the mess in boot_jump_linux().
> - Add CONFIG_ARM64_SUPPORT_AARCH32 to detect for some ARM64 system doesn't support AArch32 state.
> 
> Changes in v2:
> - armv8_switch_to_el2_aarch32() is removed. armv8_switch_to_el2_m is used
>   to switch to AArch64 EL2 or AArch32 Hyp.
> - armv8_switch_to_el1_aarch32() is removed. armv8_switch_to_el1_m is used
>   to switch to AArch64 EL1 or AArch32 SVC.
> 
>  arch/arm/Kconfig                |   6 ++
>  arch/arm/cpu/armv8/transition.S |   8 +-
>  arch/arm/include/asm/macro.h    | 174 ++++++++++++++++++++++++++++++----------
>  arch/arm/include/asm/system.h   | 118 ++++++++++++++++++++++++++-
>  arch/arm/lib/bootm.c            |  19 ++++-
>  common/image-fit.c              |  14 +++-
>  6 files changed, 287 insertions(+), 52 deletions(-)
> 
> diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
> index 729b181..794cb4f 100644
> --- a/arch/arm/Kconfig
> +++ b/arch/arm/Kconfig
> @@ -77,6 +77,12 @@ config SYS_L2CACHE_OFF
>  	  If SoC does not support L2CACHE or one do not want to enable
>  	  L2CACHE, choose this option.
>  
> +config ARM64_SUPPORT_AARCH32
> +	bool "ARM64 system support AArch32 execution state"
> +	default y if ARM64 && !CONFIG_THUNDERX
> +	help
> +	  This ARM64 system supports AArch32 execution state.
> +
>  choice
>  	prompt "Target select"
>  	default TARGET_HIKEY
> diff --git a/arch/arm/cpu/armv8/transition.S b/arch/arm/cpu/armv8/transition.S
> index 253a39b..417e8b4 100644
> --- a/arch/arm/cpu/armv8/transition.S
> +++ b/arch/arm/cpu/armv8/transition.S
> @@ -11,13 +11,13 @@
>  #include <asm/macro.h>
>  
>  ENTRY(armv8_switch_to_el2)
> -	switch_el x0, 1f, 0f, 0f
> +	switch_el x4, 1f, 0f, 0f
>  0:	ret
> -1:	armv8_switch_to_el2_m x0
> +1:	armv8_switch_to_el2_m x0, x1, x2, x3, x4
>  ENDPROC(armv8_switch_to_el2)

Alison,

I see you are chaning macro armv8_switch_to_el2. You may have missed one in
start.S. This is the code you can't test with our ARMv8 chip.

York