Re: [U-Boot] [PATCH 1/2] arm: Set TTB XN bit in case DCACHE_OFF for LPAE mode

[Tom Rini]

On Fri, Oct 28, 2016 at 12:01:43PM +0530, Keerthy wrote:
> While we setup the mmu initially we mark set_section_dcache with
> DCACHE_OFF flag. In case of non-LPAE mode the DCACHE_OFF macro
> is rightly defined with TTB_SECT_XN_MASK set so as to mark all the
> 4GB XN. In case of LPAE mode  XN(Execute-never) bit is not set with
> DCACHE_OFF. Hence XN bit is not set by default for DCACHE_OFF which
> keeps all the regions execute okay and this leads to random speculative
> fetches in random memory regions which was eventually caught by kernel
> omap-l3-noc driver.
> 
> Fix this to mark the regions as XN by default.
> 
> Signed-off-by: Keerthy <j-keer...@ti.com>
> ---
>  arch/arm/include/asm/system.h | 2 +-
>  arch/arm/lib/cache-cp15.c     | 5 +++++
>  2 files changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/arm/include/asm/system.h b/arch/arm/include/asm/system.h
> index b928bd8..2f430ad 100644
> --- a/arch/arm/include/asm/system.h
> +++ b/arch/arm/include/asm/system.h
> @@ -329,7 +329,7 @@ static inline void set_dacr(unsigned int val)
>  
>  /* options available for data cache on each page */
>  enum dcache_option {
> -     DCACHE_OFF = TTB_SECT | TTB_SECT_MAIR(0),
> +     DCACHE_OFF = TTB_SECT | TTB_SECT_MAIR(0) | TTB_SECT_XN_MASK,
>       DCACHE_WRITETHROUGH = TTB_SECT | TTB_SECT_MAIR(1),
>       DCACHE_WRITEBACK = TTB_SECT | TTB_SECT_MAIR(2),
>       DCACHE_WRITEALLOC = TTB_SECT | TTB_SECT_MAIR(3),
> diff --git a/arch/arm/lib/cache-cp15.c b/arch/arm/lib/cache-cp15.c
> index 70e94f0..4d9903e 100644
> --- a/arch/arm/lib/cache-cp15.c
> +++ b/arch/arm/lib/cache-cp15.c
> @@ -71,8 +71,13 @@ void mmu_set_region_dcache_behaviour(phys_addr_t start, 
> size_t size,
>  
>       end = ALIGN(start + size, MMU_SECTION_SIZE) >> MMU_SECTION_SHIFT;
>       start = start >> MMU_SECTION_SHIFT;
> +#ifdef CONFIG_ARMV7_LPAE
> +     debug("%s: start=%pa, size=%zu, option=%llu\n", __func__, &start, size,
> +           option);
> +#else
>       debug("%s: start=%pa, size=%zu, option=%d\n", __func__, &start, size,
>             option);
> +#endif

Does it really make sense to be printing option in decimal rather than
hex here?

-- 
Tom

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