[PATCH 1/2] Support perf script -F brstack,dso and brstacksym,dso

[Mark Santaniello]

Perf script can report the dso for "addr" and "ip" fields.
This adds the same support for the "brstack" and "brstacksym" fields.
This can be helpful for AutoFDO: we can ignore LBR entries unless the
source and target address are both in the target module we are about to
build.

I built a small test akin to "while(1) { do_nothing(); }" where the
do_nothing function is loaded from a dso:

  ~/src/burncpu$ cat burncpu.cpp
  #include <dlfcn.h>

  int main() {
    void* handle = dlopen("./dso.so", RTLD_LAZY);
    if (!handle) return -1;

    typedef void (*fp)();
    fp do_nothing = (fp) dlsym(handle, "do_nothing");

    while(1) {
      do_nothing();
    }
  }

  ~/src/burncpu$ cat dso.cpp
  extern "C" void do_nothing() {}

  ~/src/burncpu$ cat build.sh
  #!/bin/bash
  g++ -shared dso.cpp -o dso.so
  g++ burncpu.cpp -o burncpu -ldl

I sampled the execution with perf record -b.  Using the new perf script
functionality I can easily find cases where there was a transition from one
dso to another:

  $ ./perf record -a -b -- sleep 5
  [ perf record: Woken up 55 times to write data ]
  [ perf record: Captured and wrote 18.815 MB perf.data (43593 samples) ]

  $ ./perf script -F brstack,dso | sed 's/\/0 /\/0\n/g' \
  > | grep burncpu | grep dso.so | head -n 1
  0x7f967139b6aa(/tmp/burncpu/dso.so)/0x4006b1(/tmp/burncpu/exe)/P/-/-/0

  $ ./perf script -F brstacksym,dso | sed 's/\/0 /\/0\n/g' \
  > | grep burncpu | grep dso.so | head -n 1
  do_nothing+0x5(/tmp/burncpu/dso.so)/main+0x44(/tmp/burncpu/exe)/P/-/-/0

Signed-off-by: Mark Santaniello <marksan@xxxxxx>
---
 tools/perf/builtin-script.c | 61 ++++++++++++++++++++++++++++++++++++---------
 1 file changed, 49 insertions(+), 12 deletions(-)

diff --git a/tools/perf/builtin-script.c b/tools/perf/builtin-script.c
index 4761b0d..6a7033b 100644
--- a/tools/perf/builtin-script.c
+++ b/tools/perf/builtin-script.c
@@ -298,10 +298,11 @@ static int perf_evsel__check_attr(struct perf_evsel *evsel,
 		       "selected.\n");
 		return -EINVAL;
 	}
-	if (PRINT_FIELD(DSO) && !PRINT_FIELD(IP) && !PRINT_FIELD(ADDR)) {
-		pr_err("Display of DSO requested but neither sample IP nor "
-			   "sample address\nis selected. Hence, no addresses to convert "
-		       "to DSO.\n");
+	if (PRINT_FIELD(DSO) && !PRINT_FIELD(IP) && !PRINT_FIELD(ADDR) &&
+	    !PRINT_FIELD(BRSTACK) && !PRINT_FIELD(BRSTACKSYM)) {
+		pr_err("Display of DSO requested but none of sample IP, sample address, "
+		       "brstack\nor brstacksym are selected. Hence, no addresses to "
+		       "convert to DSO.\n");
 		return -EINVAL;
 	}
 	if (PRINT_FIELD(SRCLINE) && !PRINT_FIELD(IP)) {
@@ -514,18 +515,43 @@ mispred_str(struct branch_entry *br)
 	return br->flags.predicted ? 'P' : 'M';
 }
 
-static void print_sample_brstack(struct perf_sample *sample)
+static void print_sample_brstack(struct perf_sample *sample,
+				 struct thread *thread,
+				 struct perf_event_attr *attr)
 {
 	struct branch_stack *br = sample->branch_stack;
-	u64 i;
+	struct addr_location alf, alt;
+	u64 i, from, to;
 
 	if (!(br && br->nr))
 		return;
 
 	for (i = 0; i < br->nr; i++) {
-		printf(" 0x%"PRIx64"/0x%"PRIx64"/%c/%c/%c/%d ",
-			br->entries[i].from,
-			br->entries[i].to,
+		from = br->entries[i].from;
+		to   = br->entries[i].to;
+
+		if (PRINT_FIELD(DSO)) {
+			memset(&alf, 0, sizeof(alf));
+			memset(&alt, 0, sizeof(alt));
+			thread__find_addr_map(thread, sample->cpumode, MAP__FUNCTION, from, &alf);
+			thread__find_addr_map(thread, sample->cpumode, MAP__FUNCTION, to, &alt);
+		}
+
+		printf("0x%"PRIx64, from);
+		if (PRINT_FIELD(DSO)) {
+			printf("(");
+			map__fprintf_dsoname(alf.map, stdout);
+			printf(")");
+		}
+
+		printf("/0x%"PRIx64, to);
+		if (PRINT_FIELD(DSO)) {
+			printf("(");
+			map__fprintf_dsoname(alt.map, stdout);
+			printf(")");
+		}
+
+		printf("/%c/%c/%c/%d ",
 			mispred_str( br->entries + i),
 			br->entries[i].flags.in_tx? 'X' : '-',
 			br->entries[i].flags.abort? 'A' : '-',
@@ -534,7 +560,8 @@ static void print_sample_brstack(struct perf_sample *sample)
 }
 
 static void print_sample_brstacksym(struct perf_sample *sample,
-				    struct thread *thread)
+				    struct thread *thread,
+				    struct perf_event_attr *attr)
 {
 	struct branch_stack *br = sample->branch_stack;
 	struct addr_location alf, alt;
@@ -559,8 +586,18 @@ static void print_sample_brstacksym(struct perf_sample *sample,
 			alt.sym = map__find_symbol(alt.map, alt.addr);
 
 		symbol__fprintf_symname_offs(alf.sym, &alf, stdout);
+		if (PRINT_FIELD(DSO)) {
+			printf("(");
+			map__fprintf_dsoname(alf.map, stdout);
+			printf(")");
+		}
 		putchar('/');
 		symbol__fprintf_symname_offs(alt.sym, &alt, stdout);
+		if (PRINT_FIELD(DSO)) {
+			printf("(");
+			map__fprintf_dsoname(alt.map, stdout);
+			printf(")");
+		}
 		printf("/%c/%c/%c/%d ",
 			mispred_str( br->entries + i),
 			br->entries[i].flags.in_tx? 'X' : '-',
@@ -1187,9 +1224,9 @@ static void process_event(struct perf_script *script,
 		print_sample_iregs(sample, attr);
 
 	if (PRINT_FIELD(BRSTACK))
-		print_sample_brstack(sample);
+		print_sample_brstack(sample, thread, attr);
 	else if (PRINT_FIELD(BRSTACKSYM))
-		print_sample_brstacksym(sample, thread);
+		print_sample_brstacksym(sample, thread, attr);
 
 	if (perf_evsel__is_bpf_output(evsel) && PRINT_FIELD(BPF_OUTPUT))
 		print_sample_bpf_output(sample);
-- 
2.9.3