powerpc/watchpoint: Fix length calculation for unaligned target

Watchpoint match range is always doubleword(8 bytes) aligned on
powerpc. If the given range is crossing doubleword boundary, we need
to increase the length such that next doubleword also get
covered. Ex,

          address   len = 6 bytes
                |=========.
   |------------v--|------v--------|
   | | | | | | | | | | | | | | | | |
   |---------------|---------------|
    <---8 bytes--->

In such case, current code configures hw as:
  start_addr = address & ~HW_BREAKPOINT_ALIGN
  len = 8 bytes

And thus read/write in last 4 bytes of the given range is ignored.
Fix this by including next doubleword in the length.

Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20191017093204.7511-3-ravi.bangoria@linux.ibm.com
This commit is contained in:
Ravi Bangoria 2019-10-17 15:01:59 +05:30 • committed by Michael Ellerman
commit b57aeab811
5 changed files with 56 additions and 23 deletions