[Crash-utility] [PATCH] ARM: fix vtop -C for kernel addresses

[Dave Anderson]

----- Original Message -----
> On ARM, [vtop -C task] doesn't work correctly for kernel addresses: it
> always uses swapper_pg_dir when it should be using the task's
> mm->pgd.
> 
> The patch below fixes this, and also makes ARM handle kernel threads
> like the other arches.
> 
> Rabin

The patch makes "vtop -c" conform with the other architectures, so unless
Mika has a problem with it, consider it queued for crash-6.0.5.

Thanks,
  Dave

  
> diff --git a/arm.c b/arm.c
> index 4be224e..cac9a9a 100644
> --- a/arm.c
> +++ b/arm.c
> @@ -1020,22 +1020,37 @@ static int
>  arm_uvtop(struct task_context *tc, ulong uvaddr, physaddr_t *paddr,
>  int verbose)
>  {
>  	ulong *pgd;
> -	ulong mm;
>  
>  	if (!tc)
>  		error(FATAL, "current context invalid\n");
>  
>  	*paddr = 0;
>  
> -	if (IS_KVADDR(uvaddr))
> -		return arm_kvtop(tc, uvaddr, paddr, verbose);
> +        if (is_kernel_thread(tc->task) && IS_KVADDR(uvaddr)) {
> +		ulong active_mm;
>  
> -	mm = task_mm(tc->task, TRUE);
> -	if (mm)
> -		pgd = ULONG_PTR(tt->mm_struct + OFFSET(mm_struct_pgd));
> -	else
> -		readmem(tc->mm_struct + OFFSET(mm_struct_pgd), KVADDR, &pgd,
> -			sizeof(long), "mm_struct pgd", FAULT_ON_ERROR);
> +		readmem(tc->task + OFFSET(task_struct_active_mm),
> +			KVADDR, &active_mm, sizeof(void *),
> +			"task active_mm contents", FAULT_ON_ERROR);
> +
> +		if (!active_mm)
> +			error(FATAL,
> +			     "no active_mm for this kernel thread\n");
> +
> +		readmem(active_mm + OFFSET(mm_struct_pgd),
> +			KVADDR, &pgd, sizeof(long),
> +			"mm_struct pgd", FAULT_ON_ERROR);
> +	} else {
> +		ulong mm;
> +
> +		mm = task_mm(tc->task, TRUE);
> +		if (mm)
> +			pgd = ULONG_PTR(tt->mm_struct + OFFSET(mm_struct_pgd));
> +		else
> +			readmem(tc->mm_struct + OFFSET(mm_struct_pgd),
> +				KVADDR, &pgd, sizeof(long), "mm_struct pgd",
> +				FAULT_ON_ERROR);
> +	}
>  
>  	return arm_vtop(uvaddr, pgd, paddr, verbose);
>  }
> 
> --
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