Re: [Xen-devel] [PATCH v2] xen/arm: Init traps very early

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Thu, 2014-06-19 at 15:02 +0100, Julien Grall wrote:
> The function init_traps setups the handler taken when Xen hits a 
> BUG_ON/ASSERT.

"sets up"

> If an error happen before init_traps is called, we loose the backtrace.

"lose"

> 
> When a trap is taken from HYP mode, we need to:
>     - get the processor ID, percpu has to be initialized and the
> smp_processor_id correctly set.

Wrapping.

>     - initialize current, even tho it's not used for the time being. Move the

"though"

>     debug sanity ealier.

"earlier"

> 
> Signed-off-by: Julien Grall <julien.grall@xxxxxxxxxx>
> Tested-by: Naresh Bhat <naresh.bhat@xxxxxxxxxx>
> 
> ---
>     Changes in v2:
>         - Update a comment in the code to explain why we need to be set
>         early.
>         - Move the call after smp_processor_id as it's requires to be
>         there.
>         - Move set_current(...) ealier
> ---
>  xen/arch/arm/setup.c |   11 ++++++-----
>  1 file changed, 6 insertions(+), 5 deletions(-)
> 
> diff --git a/xen/arch/arm/setup.c b/xen/arch/arm/setup.c
> index b9ce7a9..8c505cb 100644
> --- a/xen/arch/arm/setup.c
> +++ b/xen/arch/arm/setup.c
> @@ -670,6 +670,12 @@ void __init start_xen(unsigned long boot_phys_offset,
>      percpu_init_areas();
>      set_processor_id(0); /* needed early, for smp_processor_id() */
>  
> +    set_current((struct vcpu *)0xfffff000); /* debug sanity */
> +    idle_vcpu[0] = current;
> +
> +    /* Initialize traps early allow us to get backtrace when an error 
> occured */

"occurred". Typos fixed + acked + applied.

> +    init_traps();
> +
>      smp_clear_cpu_maps();
>  
>      /* This is mapped by head.S */
> @@ -706,11 +712,6 @@ void __init start_xen(unsigned long boot_phys_offset,
>  
>      gic_init();
>  
> -    set_current((struct vcpu *)0xfffff000); /* debug sanity */
> -    idle_vcpu[0] = current;
> -
> -    init_traps();
> -
>      setup_virt_paging();
>  
>      p2m_vmid_allocator_init();




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