arm64: hw_breakpoint: fix watchpoint matching for tagged pointers

arm64: hw_breakpoint: fix watchpoint matching for tagged pointers

When we take a watchpoint exception, the address that triggered the
watchpoint is found in FAR_EL1. We compare it to the address of each
configured watchpoint to see which one was hit.

The configured watchpoint addresses are untagged, while the address in
FAR_EL1 will have an address tag if the data access was done using a
tagged address. The tag needs to be removed to compare the address to
the watchpoints.

Currently we don't remove it, and as a result can report the wrong
watchpoint as being hit (specifically, always either the highest TTBR0
watchpoint or lowest TTBR1 watchpoint). This patch removes the tag.

Fixes: d50240a5f6ce ("arm64: mm: permit use of tagged pointers at EL0")
Cc: <[email protected]> # 3.12.x-
Acked-by: Mark Rutland <[email protected]>
Acked-by: Will Deacon <[email protected]>
Signed-off-by: Kristina Martsenko <[email protected]>
Signed-off-by: Catalin Marinas <[email protected]>