Re: [Xen-devel] [for-4.7] xen/arm: Don't call setup_virtual_regions multiple time

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

On Wed, May 25, 2016 at 02:14:06PM +0100, Julien Grall wrote:
> The commit 2aa925be84293b44ad587ed117184ace61b41dd6 "arm/x86: Use struct
> virtual_region to do bug, symbol, and (x86) exception tables lookup."
> has introduced virtual_region. The call to initialize those regions is
> made in init_traps which is called during each CPU bring up.
> 
> This will result to register multiple time the same region and Xen crash
> when an address is looked up.

AAh, and that would explain why I didn't see it when I ran it under
the emulator - I couldn't boot it with more than one CPU (the TIMER bug)!

> 
> This can be fixed by moving the call to setup_virtual_region directly in
> start_xen.
> 
> Signed-off-by: Julien Grall <julien.grall@xxxxxxx>
> Reported-by: Chenxia Zhao <chenxiao.zhao@xxxxxxxxx>

Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
> 
> ---
> 
> Cc: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
> 
>     This is a bug fix for Xen 4.7. Without this change, any use of
>     virtual_region (printing a symbol) could lead to a crash in Xen.
> ---
>  xen/arch/arm/setup.c | 1 +
>  xen/arch/arm/traps.c | 2 --
>  2 files changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/xen/arch/arm/setup.c b/xen/arch/arm/setup.c
> index 09ff1ea..9bc11c4 100644
> --- a/xen/arch/arm/setup.c
> +++ b/xen/arch/arm/setup.c
> @@ -722,6 +722,7 @@ void __init start_xen(unsigned long boot_phys_offset,
>      set_current((struct vcpu *)0xfffff000); /* debug sanity */
>      idle_vcpu[0] = current;
>  
> +    setup_virtual_regions(NULL, NULL);
>      /* Initialize traps early allow us to get backtrace when an error 
> occurred */
>      init_traps();
>  
> diff --git a/xen/arch/arm/traps.c b/xen/arch/arm/traps.c
> index 1828ea1..aa3e3c2 100644
> --- a/xen/arch/arm/traps.c
> +++ b/xen/arch/arm/traps.c
> @@ -102,8 +102,6 @@ integer_param("debug_stack_lines", debug_stack_lines);
>  
>  void init_traps(void)
>  {
> -    setup_virtual_regions(NULL, NULL);
> -
>      /* Setup Hyp vector base */
>      WRITE_SYSREG((vaddr_t)hyp_traps_vector, VBAR_EL2);
>  
> -- 
> 1.9.1
> 

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