[Crash-utility] Question about ARM module address range

[Dave Anderson]

----- Original Message -----
> On Thu, Jul 26, 2012 at 07:58:15AM +0200, Karlsson, Jan wrote:
> > 
> > This is the case with modules. In an example without modules the first range
> > is not present, so your assumption how it works is correct. One thing that
> > could be done to get the printout less confusing is to put 0xffffffff in
> > modules_vaddr if no modules exist (and potentially put 0 in modules_end).
> 
> Can we put there the default (0xbf000000) when there is no modules?  This thing
> is documented in kernel Documentation/arm/memory.txt - modules are always
> placed in that area no matter what. And I think it works better with live
> session as well.
> 
> Something like following patch? It still gets the first vmalloc address from
> the vmcore but if it is larger than what we expect we use the default.
> 
> Jan, Thomas,
> 
> Can you check whether this still works with vmcores that have modules loaded?
> My sample vmlinux/vmcores don't seem to have any modules loaded.

Same here -- my sample vmcores don't have any modules installed -- but I cannot
see how this patch can possibly hurt, and it certainly makes sense.  I'm going to 
queue it for crash-6.0.9 unless it gets NAK'd before I release it.

Thanks,
  Dave

> 
> diff --git a/arm.c b/arm.c
> index ea06e1a..7f63a10 100644
> --- a/arm.c
> +++ b/arm.c
> @@ -305,14 +305,20 @@ arm_init(int when)
>  			error(WARNING, "Couldn't retrieve crash_notes\n");
>  		break;
>  
> -	case POST_VM:
> +	case POST_VM: {
> +		ulong vaddr;
> +
>  		machdep->machspec->vmalloc_start_addr = vt->high_memory;
>  		/*
>  		 * Modules are placed in first vmalloc'd area. This is 16MB
>  		 * below PAGE_OFFSET.
>  		 */
> -		machdep->machspec->modules_vaddr = first_vmalloc_address();
>  		machdep->machspec->modules_end = machdep->kvbase - 1;
> +		vaddr = first_vmalloc_address();
> +		if (vaddr > machdep->machspec->modules_end)
> +			machdep->machspec->modules_vaddr = DEFAULT_MODULES_VADDR;
> +		else
> +			machdep->machspec->modules_vaddr = vaddr;
>  
>  		if (init_unwind_tables()) {
>  			if (CRASHDEBUG(1))
> @@ -323,6 +329,7 @@ arm_init(int when)
>  		}
>  		break;
>  	}
> +	}
>  }
>  
>  void
> @@ -614,7 +621,7 @@ static int
>  arm_is_module_addr(ulong vaddr)
>  {
>  	ulong modules_start;
> -	ulong modules_end = machdep->kvbase - 1;
> +	ulong modules_end = machdep->machspec->modules_end;
>  
>  	if (!MODULES_VADDR) {
>  		/*
> @@ -622,7 +629,7 @@ arm_is_module_addr(ulong vaddr)
>  		 * called, we use defaults here which is 16MB below kernel start
>  		 * address.
>  		 */
> -		modules_start = machdep->kvbase - 16 * 1024 * 1024;
> +		modules_start = DEFAULT_MODULES_VADDR;
>  	} else {
>  		modules_start = MODULES_VADDR;
>  	}
> diff --git a/defs.h b/defs.h
> index caa87c0..e775e24 100755
> --- a/defs.h
> +++ b/defs.h
> @@ -2438,6 +2438,7 @@ struct load_module {
>  
>  #define IS_VMALLOC_ADDR(X) 	arm_is_vmalloc_addr((ulong)(X))
>  
> +#define DEFAULT_MODULES_VADDR	(machdep->kvbase - 16 * 1024 * 1024)
>  #define MODULES_VADDR   	(machdep->machspec->modules_vaddr)
>  #define MODULES_END     	(machdep->machspec->modules_end)
>  #define VMALLOC_START   	(machdep->machspec->vmalloc_start_addr)
> 
> --
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