UPSTREAM: coresight: tmc-etr: Fix barrier packet insertion for perf buffer

When the ETR is used in perf mode with a larger buffer (configured
via sysfs or the default size of 1M) than the perf aux buffer size,
we end up inserting the barrier packet at the wrong offset, while
moving the offset forward. i.e, instead of the "new moved offset",
we insert it at the current hardware buffer offset. These packets
will not be visible as they are never copied and could lead to
corruption in the trace decoding side, as the decoder is not aware
that it needs to reset the decoding.

Bug: 254441685
Fixes: ec13c78d7b45 ("coresight: tmc-etr: Add barrier packets when moving offset forward")
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: stable@vger.kernel.org
Reported-by: Al Grant <al.grant@arm.com>
Tested-by: Mike Leach <mike.leach@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Link: https://lore.kernel.org/r/20201208182651.1597945-2-mathieu.poirier@linaro.org


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit 83be0b84fe846edf0c722fefe225482d5f0d7395)
Signed-off-by: Lee Jones <joneslee@google.com>
Change-Id: I9371c1f2440060c715c999608628962918dbbca9