perf script: Add 'cgroup' field for output

There's no field for the cgroup, let's add one.  To do that, users need to
specify --all-cgroup option for perf record to capture the cgroup info.

  $ perf record --all-cgroups -- true

  $ perf script -F comm,pid,cgroup
            true 337112  /user.slice/user-657345.slice/user@657345.service/...
            true 337112  /user.slice/user-657345.slice/user@657345.service/...
            true 337112  /user.slice/user-657345.slice/user@657345.service/...
            true 337112  /user.slice/user-657345.slice/user@657345.service/...

If it's recorded without the --all-cgroups, it'd complain.

  $ perf script -F comm,pid,cgroup
  Samples for 'cycles:u' event do not have CGROUP attribute set. Cannot print 'cgroup' field.
  Hint: run 'perf record --all-cgroups ...'

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: https://lore.kernel.org/r/20230126213610.3381147-1-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/Documentation/perf-script.txt

@@ -134,7 +134,7 @@ OPTIONS
         srcline, period, iregs, uregs, brstack, brstacksym, flags, bpf-output,
         brstackinsn, brstackinsnlen, brstackoff, callindent, insn, insnlen, synth,
         phys_addr, metric, misc, srccode, ipc, data_page_size, code_page_size, ins_lat,
-        machine_pid, vcpu.
+        machine_pid, vcpu, cgroup.
         Field list can be prepended with the type, trace, sw or hw,
         to indicate to which event type the field list applies.
         e.g., -F sw:comm,tid,time,ip,sym  and -F trace:time,cpu,trace
@@ -231,6 +231,9 @@ OPTIONS
 	perf inject to insert a perf.data file recorded inside a virtual machine into
 	a perf.data file recorded on the host at the same time.
 
+	The cgroup fields requires sample having the cgroup id which is saved
+	when "--all-cgroups" option is passed to 'perf record'.
+
 	Finally, a user may not set fields to none for all event types.
 	i.e., -F "" is not allowed.
 

tools/perf/builtin-script.c

@@ -59,6 +59,7 @@
 #include "util/dlfilter.h"
 #include "util/record.h"
 #include "util/util.h"
+#include "util/cgroup.h"
 #include "perf.h"
 
 #include <linux/ctype.h>
@@ -130,6 +131,7 @@ enum perf_output_field {
 	PERF_OUTPUT_BRSTACKINSNLEN  = 1ULL << 36,
 	PERF_OUTPUT_MACHINE_PID     = 1ULL << 37,
 	PERF_OUTPUT_VCPU            = 1ULL << 38,
+	PERF_OUTPUT_CGROUP          = 1ULL << 39,
 };
 
 struct perf_script {
@@ -200,6 +202,7 @@ struct output_option {
 	{.str = "brstackinsnlen", .field = PERF_OUTPUT_BRSTACKINSNLEN},
 	{.str = "machine_pid", .field = PERF_OUTPUT_MACHINE_PID},
 	{.str = "vcpu", .field = PERF_OUTPUT_VCPU},
+	{.str = "cgroup", .field = PERF_OUTPUT_CGROUP},
 };
 
 enum {
@@ -542,6 +545,12 @@ static int evsel__check_attr(struct evsel *evsel, struct perf_session *session)
 	    evsel__check_stype(evsel, PERF_SAMPLE_WEIGHT_STRUCT, "WEIGHT_STRUCT", PERF_OUTPUT_INS_LAT))
 		return -EINVAL;
 
+	if (PRINT_FIELD(CGROUP) &&
+	    evsel__check_stype(evsel, PERF_SAMPLE_CGROUP, "CGROUP", PERF_OUTPUT_CGROUP)) {
+		pr_err("Hint: run 'perf record --all-cgroups ...'\n");
+		return -EINVAL;
+	}
+
 	return 0;
 }
 
@@ -2220,6 +2229,17 @@ static void process_event(struct perf_script *script,
 	if (PRINT_FIELD(CODE_PAGE_SIZE))
 		fprintf(fp, " %s", get_page_size_name(sample->code_page_size, str));
 
+	if (PRINT_FIELD(CGROUP)) {
+		const char *cgrp_name;
+		struct cgroup *cgrp = cgroup__find(machine->env,
+						   sample->cgroup);
+		if (cgrp != NULL)
+			cgrp_name = cgrp->name;
+		else
+			cgrp_name = "unknown";
+		fprintf(fp, " %s", cgrp_name);
+	}
+
 	perf_sample__fprintf_ipc(sample, attr, fp);
 
 	fprintf(fp, "\n");
@@ -3856,7 +3876,7 @@ int cmd_script(int argc, const char **argv)
 		     "brstacksym,flags,data_src,weight,bpf-output,brstackinsn,"
 		     "brstackinsnlen,brstackoff,callindent,insn,insnlen,synth,"
 		     "phys_addr,metric,misc,srccode,ipc,tod,data_page_size,"
-		     "code_page_size,ins_lat",
+		     "code_page_size,ins_lat,machine_pid,vcpu,cgroup",
 		     parse_output_fields),
 	OPT_BOOLEAN('a', "all-cpus", &system_wide,
 		    "system-wide collection from all CPUs"),