Re: [PATCH v2 4/4] perf arm-spe: Support hardware-based PID tracing

If Arm SPE traces contain CONTEXT packets with TID info, use these
values for tracking tid of samples. Otherwise fall back to using context
switch events and display a message warning the user of possible timing
inaccuracies [1].

[1] https://lore.kernel.org/lkml/f877cfa6-9b25-6445-3806-ca44a4042eaf@arm.com/ (local)

Signed-off-by: German Gomez <redacted>
---
 tools/perf/util/arm-spe.c | 99 +++++++++++++++++++++++++++------------
 1 file changed, 70 insertions(+), 29 deletions(-)

diff --git a/tools/perf/util/arm-spe.c b/tools/perf/util/arm-spe.c
index 230bc7ab2..30b8bb48a 100644
--- a/tools/perf/util/arm-spe.c
+++ b/tools/perf/util/arm-spe.c

@@ -71,6 +71,7 @@ struct arm_spe {
        u64                             kernel_start;

        unsigned long                   num_events;
+       u8                              use_ctx_pkt_for_pid;
 };

 struct arm_spe_queue {

@@ -226,6 +227,44 @@ static inline u8 arm_spe_cpumode(struct arm_spe *spe, u64 ip)
                PERF_RECORD_MISC_USER;
 }

+static void arm_spe_set_pid_tid_cpu(struct arm_spe *spe,
+                                   struct auxtrace_queue *queue)
+{
+       struct arm_spe_queue *speq = queue->priv;
+       pid_t tid;
+
+       tid = machine__get_current_tid(spe->machine, speq->cpu);
+       if (tid != -1) {
+               speq->tid = tid;
+               thread__zput(speq->thread);
+       } else
+               speq->tid = queue->tid;
+
+       if ((!speq->thread) && (speq->tid != -1)) {
+               speq->thread = machine__find_thread(spe->machine, -1,
+                                                   speq->tid);
+       }
+
+       if (speq->thread) {
+               speq->pid = speq->thread->pid_;
+               if (queue->cpu == -1)
+                       speq->cpu = speq->thread->cpu;
+       }
+}
+
+static int arm_spe_set_tid(struct arm_spe_queue *speq, pid_t tid)
+{
+       struct arm_spe *spe = speq->spe;
+       int err = machine__set_current_tid(spe->machine, speq->cpu, tid, tid);