Note the q option does not specify what events will be synthesized e.g. the p
option must be used also to show power events.
+Repeating the q option (double-q i.e. qq) results in even faster decoding and even
+less detail. The decoder decodes only extended PSB (PSB+) packets, getting the
+instruction pointer if there is a FUP packet within PSB+ (i.e. between PSB and
+PSBEND). Note PSB packets occur regularly in the trace based on the psb_period
+config term (refer config terms section). There will be a FUP packet if the
+PSB+ occurs while control flow is being traced.
+
+What will *not* be decoded with the qq option:
+
+ - everything except instruction pointer associated with PSB packets
+
+What *will* be decoded with the qq option:
+
+ - instruction pointer associated with PSB packets
+
dump option
~~~~~~~~~~~
bool in_psb;
bool hop;
bool hop_psb_fup;
+ bool leap;
enum intel_pt_param_flags flags;
uint64_t pos;
uint64_t last_ip;
decoder->return_compression = params->return_compression;
decoder->branch_enable = params->branch_enable;
decoder->hop = params->quick >= 1;
+ decoder->leap = params->quick >= 2;
decoder->flags = params->flags;
#define HOP_RETURN 2
#define HOP_AGAIN 3
+static int intel_pt_scan_for_psb(struct intel_pt_decoder *decoder);
+
/* Hop mode: Ignore TNT, do not walk code, but get ip from FUPs and TIPs */
static int intel_pt_hop_trace(struct intel_pt_decoder *decoder, bool *no_tip, int *err)
{
+ /* Leap from PSB to PSB, getting ip from FUP within PSB+ */
+ if (decoder->leap && !decoder->in_psb && decoder->packet.type != INTEL_PT_PSB) {
+ *err = intel_pt_scan_for_psb(decoder);
+ if (*err)
+ return HOP_RETURN;
+ }
+
switch (decoder->packet.type) {
case INTEL_PT_TNT:
return HOP_IGNORE;
decoder->ip = 0;
intel_pt_clear_stack(&decoder->stack);
+leap:
err = intel_pt_scan_for_psb(decoder);
if (err)
return err;
decoder->pkt_state = INTEL_PT_STATE_RESAMPLE;
else
decoder->pkt_state = INTEL_PT_STATE_IN_SYNC;
+ } else if (decoder->leap) {
+ /*
+ * In leap mode, only PSB+ is decoded, so keeping leaping to the
+ * next PSB until there is an ip.
+ */
+ goto leap;
} else {
return intel_pt_sync_ip(decoder);
}