Re: [Qemu-devel] [PATCH v2 2/8] exec: Factor out core logic of check_watchpoint()

[Richard Henderson]

On 8/29/19 10:26 AM, Philippe Mathieu-Daudé wrote:
>> -            wp->hitaddr = vaddr;
>> +            wp->hitaddr = MAX(addr, wp->vaddr);
> 
> When is addr > wp->vaddr?

Both the watchpoint and the access are arbitrary ranges.

  wp:    [ 1000               - 1008 ]
  store:     [ 1002 - 1004 ]

  wp:               [ 1004    - 1008 ]
  store: [ 1000               - 1008 ]

The old code would, for the first case, return 1002 and not the 1000 of the
watch point, which seems reasonable.  For the second case, we would set 1000,
an address outside of the watchpoint.

David's change makes sure that the address signaled is inside the watchpoint.
I.e. leaving the first case unchanged and making the second  set 1004.

It seems very reasonable to me.


r~