tree c5862947e6fe06a935452a7e0d967868fa27bed0
parent 05cf88e7c276d6d79eab70f27470ea955e80a658
author Giacomo Travaglini <giacomo.travaglini@arm.com> 1649419383 +0100
committer Giacomo Travaglini <giacomo.travaglini@arm.com> 1651574419 +0000

arch-arm: Split purifyTaggedAddr in two sub-functions

This patch is splitting the purifyTaggedAddr helper in two
by introducing the maskTaggedAddress utility

* The first part computes the top bit of the address (computeAddrTop)
(This is required as the MSBs of a VA could be used to store
tags like in FEAT_Pauth)

* The second part applies some masking to the supplied
address (maskTaggedAddress) depending on the top bit to
purify the VA from the TAG

The motivation of this split will be clear in the next patch:
we want to memoize the expensive computeAddrTop. Memoizing
purifyTaggedAddr is inefficient as the first argument
is the VA of the memory request so multiple memory requests
will allocate multiple entries in the results cache and
memoization will rarely be used.

We will memoize the VA agnostic computeAddrTop instead

Change-Id: Ib3d8bb521be67a1f21c0891e753396299adf500b
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/59150
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Richard Cooper <richard.cooper@arm.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>