Re: [v2] powernv:idle: Fix bug due to labeling ambiguity in power_enter_stop

From: Michael Ellerman
Date: Wed Mar 08 2017 - 02:49:05 EST

On Mon, 2017-02-27 at 05:40:07 UTC, "Gautham R. Shenoy" wrote:
> From: "Gautham R. Shenoy" <ego@xxxxxxxxxxxxxxxxxx>
> Commit 09206b600c76 ("powernv: Pass PSSCR value and mask to
> power9_idle_stop") added additional code in power_enter_stop() to
> distinguish between stop requests whose PSSCR had ESL=EC=1 from those
> which did not. When ESL=EC=1, we do a forward-jump to a location
> labelled by "1", which had the code to handle the ESL=EC=1 case.
> Unforunately just a couple of instructions before this label, is the
> macro IDLE_STATE_ENTER_SEQ() which also has a label "1" in its
> expansion.
> As a result, the current code can result in directly executing stop
> instruction for deep stop requests with PSSCR ESL=EC=1, without saving
> the hypervisor state.
> Fix this BUG by labeling the location that handles ESL=EC=1 case with
> a more descriptive label ".Lhandle_esl_ec_set" (local label suggestion
> a la .Lxx from Anton Blanchard).
> While at it, rename the label "2" labelling the location of the code
> handling entry into deep stop states with ".Lhandle_deep_stop".
> For a good measure, change the label in IDLE_STATE_ENTER_SEQ() macro
> to an not-so commonly used value in order to avoid similar mishaps in
> the future.
> Fixes: 09206b600c76 ("powernv: Pass PSSCR value and mask to
> power9_idle_stop")
> Cc: Michael Neuling <mikey@xxxxxxxxxxx>
> Cc: Vaidyanathan Srinivasan <svaidy@xxxxxxxxxxxxxxxxxx>
> Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
> Signed-off-by: Gautham R. Shenoy <ego@xxxxxxxxxxxxxxxxxx>

Applied to powerpc fixes, thanks.