[U-Boot] [PATCH v4 3/4] arm: relocate the exception vectors

[Albert ARIBAUD <albert.u.boot@aribaud.net>]

Hello Georges,

On Tue, 28 Oct 2014 23:16:11 +0100, Georges Savoundararadj <savoundg@gmail.com> wrote:
> This commit relocates the exception vectors.
> As ARM1176 and ARMv7 have the security extensions, it uses VBAR.  For
> the other ARM processors, it copies the relocated exception vectors to
> the correct address: 0x00000000 or 0xFFFF0000.
> 
> Signed-off-by: Georges Savoundararadj <savoundg@gmail.com>
> Cc: Albert Aribaud <albert.u.boot@aribaud.net>
> Cc: Tom Warren <twarren@nvidia.com>
> 
> ---
> This patch needs some tests because it impacts many boards. I have
> tested it with my raspberry pi in the two cases: using VBAR and
> using the copied exception vectors.
> 
> Changes in v4: None
> Changes in v3:
> - Use the CPU feature HAS_VBAR Kconfig symbol
> 
> Changes in v2:
> - Relocate exception vectors also on processors which do not support
>   security extensions
> - Reword the commit message
> 
>  arch/arm/cpu/armv7/start.S |  6 ------
>  arch/arm/lib/relocate.S    | 30 ++++++++++++++++++++++++++++++
>  2 files changed, 30 insertions(+), 6 deletions(-)
> 
> diff --git a/arch/arm/cpu/armv7/start.S b/arch/arm/cpu/armv7/start.S
> index fedd7c8..fdc05b9 100644
> --- a/arch/arm/cpu/armv7/start.S
> +++ b/arch/arm/cpu/armv7/start.S
> @@ -81,12 +81,6 @@ ENTRY(c_runtime_cpu_setup)
>  	mcr     p15, 0, r0, c7, c10, 4	@ DSB
>  	mcr     p15, 0, r0, c7, c5, 4	@ ISB
>  #endif
> -/*
> - * Move vector table
> - */
> -	/* Set vector address in CP15 VBAR register */
> -	ldr     r0, =_start
> -	mcr     p15, 0, r0, c12, c0, 0  @Set VBAR
>  
>  	bx	lr
>  
> diff --git a/arch/arm/lib/relocate.S b/arch/arm/lib/relocate.S
> index 8035251..b4a258c 100644
> --- a/arch/arm/lib/relocate.S
> +++ b/arch/arm/lib/relocate.S
> @@ -6,6 +6,8 @@
>   * SPDX-License-Identifier:	GPL-2.0+
>   */
>  
> +#include <asm-offsets.h>
> +#include <config.h>
>  #include <linux/linkage.h>
>  
>  /*
> @@ -52,6 +54,34 @@ fixnext:
>  	cmp	r2, r3
>  	blo	fixloop
>  
> +	/*
> +	 * Relocate the exception vectors
> +	 */
> +#ifdef CONFIG_HAS_VBAR
> +	/*
> +	 * If the ARM processor has the security extensions,
> +	 * use VBAR to relocate the exception vectors.
> +	 */
> +	ldr	r0, [r9, #GD_RELOCADDR]	/* r0 = gd->relocaddr */
> +	mcr     p15, 0, r0, c12, c0, 0  /* Set VBAR */
> +#else
> +	/*
> +	 * Copy the relocated exception vectors to the
> +	 * correct address
> +	 * CP15 c1 V bit gives us the location of the vectors:
> +	 * 0x00000000 or 0xFFFF0000.
> +	 */
> +	ldr	r0, [r9, #GD_RELOCADDR]	/* r0 = gd->relocaddr */
> +	mrc	p15, 0, r2, c1, c0, 0	/* V bit (bit[13]) in CP15 c1 */
> +	ands	r2, r2, #(1 << 13)
> +	ldreq	r1, =0x00000000 	/* If V=0 */
> +	ldrne	r1, =0xFFFF0000 	/* If V=1 */
> +	ldmia	r0!, {r2-r8,r10}
> +	stmia	r1!, {r2-r8,r10}
> +	ldmia	r0!, {r2-r8,r10}
> +	stmia	r1!, {r2-r8,r10}
> +#endif
> +
>  relocate_done:
>  
>  #ifdef __XSCALE__
> -- 
> 2.1.2
> 

Acked-by: Albert ARIBAUD <albert.u.boot@aribaud.net>

Amicalement,
-- 
Albert.