[PATCH] powerpc/perf: Fix the event alternatives array to have correct sort order

[Athira Rajeev]

Platform specific PMU supports alternative event for some
of the event codes. During perf_event_open, if any event
group doesn't match constraint check criteria, further lookup
is done to find alternative event. Code checks to see if
it is possible to schedule event as group using alternative
events.

Currently the array of alternatives events in PMU code is expected
to be sorted by column 0. This is because in find_alternative()
function, the return criteria is based on event code comparison.
ie "event < ev_alt[i][0])". If the input "event" code is less
than event code in table of alternative events, the search will end.
This optimisation that it has to be sorted is used since
find_alternative() potentially gets called a lot. In power9/power10
PMU code, the alternative event array is not sorted list and hence
there is breakage in finding alternative event.

To work with existing logic, fix the alternative event array
to be sorted by column 0 for power9-pmu.c and power10-pmu.c

Signed-off-by: Athira Rajeev <atrajeev at linux.vnet.ibm.com>
---
 arch/powerpc/perf/power10-pmu.c | 2 +-
 arch/powerpc/perf/power9-pmu.c  | 8 ++++----
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/arch/powerpc/perf/power10-pmu.c b/arch/powerpc/perf/power10-pmu.c
index d3398100a60f..c6d51e7093cf 100644
--- a/arch/powerpc/perf/power10-pmu.c
+++ b/arch/powerpc/perf/power10-pmu.c
@@ -91,8 +91,8 @@ extern u64 PERF_REG_EXTENDED_MASK;
 
 /* Table of alternatives, sorted by column 0 */
 static const unsigned int power10_event_alternatives[][MAX_ALT] = {
-	{ PM_CYC_ALT,			PM_CYC },
 	{ PM_INST_CMPL_ALT,		PM_INST_CMPL },
+	{ PM_CYC_ALT,			PM_CYC },
 };
 
 static int power10_get_alternatives(u64 event, unsigned int flags, u64 alt[])
diff --git a/arch/powerpc/perf/power9-pmu.c b/arch/powerpc/perf/power9-pmu.c
index c9eb5232e68b..c393e837648e 100644
--- a/arch/powerpc/perf/power9-pmu.c
+++ b/arch/powerpc/perf/power9-pmu.c
@@ -133,11 +133,11 @@ int p9_dd22_bl_ev[] = {
 
 /* Table of alternatives, sorted by column 0 */
 static const unsigned int power9_event_alternatives[][MAX_ALT] = {
-	{ PM_INST_DISP,			PM_INST_DISP_ALT },
-	{ PM_RUN_CYC_ALT,		PM_RUN_CYC },
-	{ PM_RUN_INST_CMPL_ALT,		PM_RUN_INST_CMPL },
-	{ PM_LD_MISS_L1,		PM_LD_MISS_L1_ALT },
 	{ PM_BR_2PATH,			PM_BR_2PATH_ALT },
+	{ PM_INST_DISP,			PM_INST_DISP_ALT },
+	{ PM_RUN_CYC_ALT,               PM_RUN_CYC },
+	{ PM_LD_MISS_L1,                PM_LD_MISS_L1_ALT },
+	{ PM_RUN_INST_CMPL_ALT,         PM_RUN_INST_CMPL },
 };
 
 static int power9_get_alternatives(u64 event, unsigned int flags, u64 alt[])
-- 
2.35.1