perf intel-pt: Add PSB events

Emitting a PSB+ can cause a CPU a slight delay. When doing timing analysis
of code with Intel PT, it is useful to know if a timing bubble was caused
by Intel PT or not. Add reporting of PSB events via perf script. PSB
events are printed with the existing itrace 'p' option which also prints
power and frequency changes. The PSB event contains the trace offset at
which the PSB occurs, to allow easy reference back to the PSB+ packets.

The PSB event timestamp is always the timestamp from the PSB+ TSC
packet, and the ip is always the address from the PSB+ FUP packet.

The code changes are non-trivial because the decoder must walk to the
PSB+ FUP address before outputting the PSB event.

Example:

  $ perf record -e intel_pt/cyc,psb_period=0/u uname
  Linux
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.046 MB perf.data ]
  $ perf script --itrace=p --ns
     perf 17981 [006] 25617.510820383:  psb:  psb offs: 0                               0 [unknown] ([unknown])
     perf 17981 [006] 25617.510820383:  cbr:  cbr: 42 freq: 4219 MHz (156%)             0 [unknown] ([unknown])
    uname 17981 [006] 25617.510889753:  psb:  psb offs: 0xb50                7f78c12a212e __GI___tunables_init+0xee (/usr/lib/x86_64-linux-gnu/ld-2.31.so)
    uname 17981 [006] 25617.510899162:  psb:  psb offs: 0x12d0               7f78c128af1c dl_main+0x93c (/usr/lib/x86_64-linux-gnu/ld-2.31.so)
    uname 17981 [006] 25617.510939242:  psb:  psb offs: 0x1a50               7f78c128eefc _dl_map_object_from_fd+0x13c (/usr/lib/x86_64-linux-gnu/ld-2.31.so)
    uname 17981 [006] 25617.510981274:  psb:  psb offs: 0x21c8               7f78c1296307 _dl_relocate_object+0x927 (/usr/lib/x86_64-linux-gnu/ld-2.31.so)
    uname 17981 [006] 25617.510993034:  psb:  psb offs: 0x2948               7f78c12940e4 _dl_lookup_symbol_x+0x14 (/usr/lib/x86_64-linux-gnu/ld-2.31.so)
    uname 17981 [006] 25617.511003871:  psb:  psb offs: 0x30c8               7f78c12937b3 do_lookup_x+0x2f3 (/usr/lib/x86_64-linux-gnu/ld-2.31.so)
    uname 17981 [006] 25617.511019854:  psb:  psb offs: 0x3850               7f78c1295eed _dl_relocate_object+0x50d (/usr/lib/x86_64-linux-gnu/ld-2.31.so)
    uname 17981 [006] 25617.511029015:  psb:  psb offs: 0x4390               7f78c12a855a strcmp+0xf6a (/usr/lib/x86_64-linux-gnu/ld-2.31.so)
    uname 17981 [006] 25617.511064876:  psb:  psb offs: 0x4b10                          0 [unknown] ([unknown])
    uname 17981 [006] 25617.511080762:  psb:  psb offs: 0x5290               7f78c11db53d _dl_addr+0x13d (/usr/lib/x86_64-linux-gnu/libc-2.31.so)
    uname 17981 [006] 25617.511086035:  psb:  psb offs: 0x5a08               7f78c11db538 _dl_addr+0x138 (/usr/lib/x86_64-linux-gnu/libc-2.31.so)
    uname 17981 [006] 25617.511091381:  psb:  psb offs: 0x6190               7f78c11db534 _dl_addr+0x134 (/usr/lib/x86_64-linux-gnu/libc-2.31.so)
    uname 17981 [006] 25617.511096681:  psb:  psb offs: 0x6910               7f78c11db4c3 _dl_addr+0xc3 (/usr/lib/x86_64-linux-gnu/libc-2.31.so)
    uname 17981 [006] 25617.511119520:  psb:  psb offs: 0x7090               7f78c10ada5e _nl_intern_locale_data+0x12e (/usr/lib/x86_64-linux-gnu/libc-2.31.so)
    uname 17981 [006] 25617.511126584:  psb:  psb offs: 0x7818               7f78c10ada50 _nl_intern_locale_data+0x120 (/usr/lib/x86_64-linux-gnu/libc-2.31.so)
    uname 17981 [006] 25617.511132775:  psb:  psb offs: 0x8358               7f78c10c20c0 getenv+0xa0 (/usr/lib/x86_64-linux-gnu/libc-2.31.so)
    uname 17981 [006] 25617.511134598:  psb:  psb offs: 0x8ad0               7f78c10ada09 _nl_intern_locale_data+0xd9 (/usr/lib/x86_64-linux-gnu/libc-2.31.so)
    uname 17981 [006] 25617.511135685:  psb:  psb offs: 0x9258               7f78c10ada50 _nl_intern_locale_data+0x120 (/usr/lib/x86_64-linux-gnu/libc-2.31.so)
    uname 17981 [006] 25617.511138322:  psb:  psb offs: 0x99d0               7f78c11fffd9 __strncmp_avx2+0x39 (/usr/lib/x86_64-linux-gnu/libc-2.31.so)
    uname 17981 [006] 25617.511158907:  psb:  psb offs: 0xa150                          0 [unknown] ([unknown])

Signed-off-by: Adrian Hunter <[email protected]>
Reviewed-by: Andi Kleen <[email protected]>
Cc: Jiri Olsa <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

Author: ahunter6

tools/perf/Documentation/itrace.txt

@@ -4,7 +4,7 @@
 		r	synthesize branches events (returns only)
 		x	synthesize transactions events
 		w	synthesize ptwrite events
-		p	synthesize power events
+		p	synthesize power events (incl. PSB events for Intel PT)
 		o	synthesize other events recorded due to the use
 			of aux-output (refer to perf record)
 		e	synthesize error events

tools/perf/Documentation/perf-intel-pt.txt

@@ -858,7 +858,7 @@ The letters are:
 	b	synthesize "branches" events
 	x	synthesize "transactions" events
 	w	synthesize "ptwrite" events
-	p	synthesize "power" events
+	p	synthesize "power" events (incl. PSB events)
 	c	synthesize branches events (calls only)
 	r	synthesize branches events (returns only)
 	e	synthesize tracing error events
@@ -913,6 +913,11 @@ Where:
 For more details refer to the Intel 64 and IA-32 Architectures Software
 Developer Manuals.
 
+PSB events show when a PSB+ occurred and also the byte-offset in the trace.
+Emitting a PSB+ can cause a CPU a slight delay. When doing timing analysis
+of code with Intel PT, it is useful to know if a timing bubble was caused
+by Intel PT or not.
+
 Error events show where the decoder lost the trace.  Error events
 are quite important.  Users must know if what they are seeing is a complete
 picture or not. The "e" option may be followed by flags which affect what errors

tools/perf/builtin-script.c

@@ -1766,6 +1766,18 @@ static int perf_sample__fprintf_synth_cbr(struct perf_sample *sample, FILE *fp)
 	return len + perf_sample__fprintf_pt_spacing(len, fp);
 }
 
+static int perf_sample__fprintf_synth_psb(struct perf_sample *sample, FILE *fp)
+{
+	struct perf_synth_intel_psb *data = perf_sample__synth_ptr(sample);
+	int len;
+
+	if (perf_sample__bad_synth_size(sample, *data))
+		return 0;
+
+	len = fprintf(fp, " psb offs: %#" PRIx64, data->offset);
+	return len + perf_sample__fprintf_pt_spacing(len, fp);
+}
+
 static int perf_sample__fprintf_synth(struct perf_sample *sample,
 				      struct evsel *evsel, FILE *fp)
 {
@@ -1782,6 +1794,8 @@ static int perf_sample__fprintf_synth(struct perf_sample *sample,
 		return perf_sample__fprintf_synth_pwrx(sample, fp);
 	case PERF_SYNTH_INTEL_CBR:
 		return perf_sample__fprintf_synth_cbr(sample, fp);
+	case PERF_SYNTH_INTEL_PSB:
+		return perf_sample__fprintf_synth_psb(sample, fp);
 	default:
 		break;
 	}

tools/perf/util/event.h

@@ -173,6 +173,7 @@ enum perf_synth_id {
 	PERF_SYNTH_INTEL_EXSTOP,
 	PERF_SYNTH_INTEL_PWRX,
 	PERF_SYNTH_INTEL_CBR,
+	PERF_SYNTH_INTEL_PSB,
 };
 
 /*
@@ -265,6 +266,12 @@ struct perf_synth_intel_cbr {
 	u32 reserved3;
 };
 
+struct perf_synth_intel_psb {
+	u32 padding;
+	u32 reserved;
+	u64 offset;
+};
+
 /*
  * raw_data is always 4 bytes from an 8-byte boundary, so subtract 4 to get
  * 8-byte alignment.