[Crash-utility] [PATCH] s390x: fix interrupt stack address calculation

[Dave Anderson]

----- Original Message -----
> The kernel commit 2f859d0dad8 ("s390/smp: reduce size of struct pcpu")
> for linux-4.0 removed the "async_stack" and "panic_stack" members from
> "struct pcpu".
> 
> So now the only option to find out the stack address is using "struct
> lowcore" (again). Unfortunately we don't get the exact address because
> since commit dc7ee00d477 ("s390: lowcore stack pointer offsets") the stack
> frame overhead is already subtracted from the addresses. Therefore we
> have to roundup the stack address to PAGE_SIZE.
> 
> Signed-off-by: Michael Holzheu <holzheu at linux.vnet.ibm.com>

Hi Michael,

For the changelog -- what's the symptom of the failure?

Dave

> ---
>  s390x.c |    7 +++----
>  1 file changed, 3 insertions(+), 4 deletions(-)
> 
> --- a/s390x.c
> +++ b/s390x.c
> @@ -1027,8 +1027,6 @@ static unsigned long get_int_stack_pcpu(
>  {
>  	unsigned long addr;
>  
> -	if (!MEMBER_EXISTS("pcpu", stack_name))
> -		return 0;
>  	addr = symbol_value("pcpu_devices") +
>  		cpu * STRUCT_SIZE("pcpu") + MEMBER_OFFSET("pcpu", stack_name);
>  	return readmem_ul(addr) + INT_STACK_SIZE;
> @@ -1041,7 +1039,8 @@ static unsigned long get_int_stack_lc(ch
>  {
>  	if (!MEMBER_EXISTS(lc_struct, stack_name))
>  		return 0;
> -	return ULONG(lc + MEMBER_OFFSET(lc_struct, stack_name));
> +	return roundup(ULONG(lc + MEMBER_OFFSET(lc_struct, stack_name)),
> +			     PAGESIZE());
>  }
>  
>  /*
> @@ -1057,7 +1056,7 @@ static void get_int_stack(char *stack_na
>  		stack_addr = symbol_value("restart_stack");
>  		stack_addr = readmem_ul(stack_addr);
>  	} else {
> -		if (symbol_exists("pcpu_devices"))
> +		if (symbol_exists("pcpu_devices") && MEMBER_EXISTS("pcpu", stack_name))
>  			stack_addr = get_int_stack_pcpu(stack_name, cpu);
>  		else
>  			stack_addr = get_int_stack_lc(stack_name, lc);
>