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Date: Thu, 5 Apr 2018 09:54:02 +0200
From: Sascha Hauer <s.hauer@pengutronix.de>
Message-ID: <20180405075402.gbplqqwoubu7cqpg@pengutronix.de>
References: <20180326192025.28809-1-l.stach@pengutronix.de>
 <20180326192025.28809-4-l.stach@pengutronix.de>
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Subject: Re: [PATCH v3 04/10] ARM: add file for HYP mode related setup
To: Lucas Stach <l.stach@pengutronix.de>
Cc: barebox@lists.infradead.org

On Mon, Mar 26, 2018 at 09:20:19PM +0200, Lucas Stach wrote:
> This adds routines to add hyp mode vectors and switch back to HYP
> mode from SVC. This is needed in both the PBL and Barebox proper.
> 
> Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
> Tested-by: Roland Hieber <r.hieber@pengutronix.de>
> ---
> v3:
> - fix whitespace
> - use __BARE_INIT
> ---
>  arch/arm/cpu/Makefile         |   4 ++
>  arch/arm/cpu/hyp.S            | 116 ++++++++++++++++++++++++++++++++++++++++++
>  arch/arm/cpu/sm_as.S          |  11 ----
>  arch/arm/include/asm/secure.h |   8 +++
>  4 files changed, 128 insertions(+), 11 deletions(-)
>  create mode 100644 arch/arm/cpu/hyp.S
> 
> diff --git a/arch/arm/cpu/Makefile b/arch/arm/cpu/Makefile
> index 13fe12c31f6f..f86dff975bb4 100644
> --- a/arch/arm/cpu/Makefile
> +++ b/arch/arm/cpu/Makefile
> @@ -9,6 +9,10 @@ obj-$(CONFIG_ARM_EXCEPTIONS) += exceptions.o
>  obj-$(CONFIG_MMU) += mmu.o mmu-early.o
>  pbl-$(CONFIG_MMU) += mmu-early.o
>  lwl-y += lowlevel.o
> +obj-y += hyp.o
> +AFLAGS_hyp.o :=-Wa,-march=armv7-a -Wa,-mcpu=all
> +pbl-y += hyp.o
> +AFLAGS_pbl-hyp.o :=-Wa,-march=armv7-a -Wa,-mcpu=all
>  endif
>  
>  obj-$(CONFIG_ARM_EXCEPTIONS) += interrupts.o
> diff --git a/arch/arm/cpu/hyp.S b/arch/arm/cpu/hyp.S
> new file mode 100644
> index 000000000000..1314b56eab25
> --- /dev/null
> +++ b/arch/arm/cpu/hyp.S
> @@ -0,0 +1,116 @@
> +#include <linux/linkage.h>
> +#include <asm/system.h>
> +#include <asm/opcodes-virt.h>
> +#include <init.h>
> +
> +.arch_extension sec
> +.arch_extension virt
> +
> +__BARE_INIT
> +
> +.data
> +	.align  2
> +ENTRY(__boot_cpu_mode)
> +	.long   0
> +.text
> +
> +ENTRY(__hyp_install)
> +	mrs	r12, cpsr
> +	and	r12, r12, #MODE_MASK
> +
> +	@ Save the initial CPU state
> +	adr	r0, .L__boot_cpu_mode_offset
> +	ldr	r1, [r0]
> +	str	r12, [r0, r1]

Naa, this won't work. You save the cpsr value in __boot_cpu_mode, but
this variable exists both in PBL and regular barebox, __hyp_install
is called multiple times and cpsr is modified right after saving it.

Sascha

-- 
Pengutronix e.K.                           |                             |
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