Re: NMI watchdog: BUG: soft lockup

[James Clarke <jrtc27@jrtc27.com>]

> On 25 Oct 2016, at 18:27, David Miller <davem@davemloft.net> wrote:
> 
> From: David Miller <davem@davemloft.net>
> Date: Tue, 25 Oct 2016 13:18:08 -0400 (EDT)
> 
>> So the full virtual address comparison is something like:
>> 
>> 	unsigned long compare = (tag >> 22) << 22; /* Clear CONTEXT bits */
>> 
>> 	compare |= (tsb_index & (nentries - 1)) << 13;
>> 
>> 	if (vaddr == compare)
>> 		goto match;
>> 
>> The swapper TSB only stores PAGE_SIZE translations.
> 
> Ok, this should work:
> 
> static void flush_tsb_kernel_range_scan(unsigned long start, unsigned long end)
> {
>        unsigned long idx;
> 
>        for (idx = 0; idx < KERNEL_TSB_NENTRIES; idx++) {
>                struct tsb *ent = &swapper_tsb[idx];
>                unsigned long match = idx << 13;
> 
>                match |= (ent->tag << 22);
>                if (match >= start && match < end)
>                        ent->tag = (1UL << TSB_TAG_INVALID_BIT);
>        }
> }
> 
> Bits 13-"21+N" come from the TSB index, and the tag always stores
> bits 22 and above.  So simply 'or'ing them together always gives
> us a usable match value.

Ah, right, got it. That makes it much nicer than mine.

James