perf annotate: Add basic support for bpf_image

Add the DSO_BINARY_TYPE__BPF_IMAGE dso binary type to recognize BPF
images that carry trampoline or dispatcher.

Upcoming patches will add support to read the image data, store it
within the BPF feature in perf.data and display it for annotation
purposes.

Currently we only display following message:

  # ./perf annotate bpf_trampoline_24456 --stdio
   Percent |      Source code & Disassembly of . for cycles (504  ...
  --------------------------------------------------------------- ...
           :       to be implemented
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andrii Nakryiko <andriin@fb.com>
Cc: Björn Töpel <bjorn.topel@intel.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: David S. Miller <davem@redhat.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Jesper Dangaard Brouer <hawk@kernel.org>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: Martin KaFai Lau <kafai@fb.com>
Cc: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20200312195610.346362-16-jolsa@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/annotate.c

@@ -1821,6 +1821,24 @@ static int symbol__disassemble_bpf(struct symbol *sym __maybe_unused,
 }
 #endif // defined(HAVE_LIBBFD_SUPPORT) && defined(HAVE_LIBBPF_SUPPORT)
 
+static int
+symbol__disassemble_bpf_image(struct symbol *sym,
+			      struct annotate_args *args)
+{
+	struct annotation *notes = symbol__annotation(sym);
+	struct disasm_line *dl;
+
+	args->offset = -1;
+	args->line = strdup("to be implemented");
+	args->line_nr = 0;
+	dl = disasm_line__new(args);
+	if (dl)
+		annotation_line__add(&dl->al, &notes->src->source);
+
+	free(args->line);
+	return 0;
+}
+
 /*
  * Possibly create a new version of line with tabs expanded. Returns the
  * existing or new line, storage is updated if a new line is allocated. If
@@ -1920,6 +1938,8 @@ static int symbol__disassemble(struct symbol *sym, struct annotate_args *args)
 
 	if (dso->binary_type == DSO_BINARY_TYPE__BPF_PROG_INFO) {
 		return symbol__disassemble_bpf(sym, args);
+	} else if (dso->binary_type == DSO_BINARY_TYPE__BPF_IMAGE) {
+		return symbol__disassemble_bpf_image(sym, args);
 	} else if (dso__is_kcore(dso)) {
 		kce.kcore_filename = symfs_filename;
 		kce.addr = map__rip_2objdump(map, sym->start);

tools/perf/util/dso.c

@@ -191,6 +191,7 @@ int dso__read_binary_type_filename(const struct dso *dso,
 	case DSO_BINARY_TYPE__GUEST_KALLSYMS:
 	case DSO_BINARY_TYPE__JAVA_JIT:
 	case DSO_BINARY_TYPE__BPF_PROG_INFO:
+	case DSO_BINARY_TYPE__BPF_IMAGE:
 	case DSO_BINARY_TYPE__NOT_FOUND:
 		ret = -1;
 		break;

tools/perf/util/dso.h

@@ -40,6 +40,7 @@ enum dso_binary_type {
 	DSO_BINARY_TYPE__GUEST_KCORE,
 	DSO_BINARY_TYPE__OPENEMBEDDED_DEBUGINFO,
 	DSO_BINARY_TYPE__BPF_PROG_INFO,
+	DSO_BINARY_TYPE__BPF_IMAGE,
 	DSO_BINARY_TYPE__NOT_FOUND,
 };
 

tools/perf/util/machine.c

@@ -736,6 +736,12 @@ int machine__process_switch_event(struct machine *machine __maybe_unused,
 	return 0;
 }
 
+static int is_bpf_image(const char *name)
+{
+	return strncmp(name, "bpf_trampoline_", sizeof("bpf_trampoline_") - 1) ||
+	       strncmp(name, "bpf_dispatcher_", sizeof("bpf_dispatcher_") - 1);
+}
+
 static int machine__process_ksymbol_register(struct machine *machine,
 					     union perf_event *event,
 					     struct perf_sample *sample __maybe_unused)
@@ -760,6 +766,11 @@ static int machine__process_ksymbol_register(struct machine *machine,
 		map->end = map->start + event->ksymbol.len;
 		maps__insert(&machine->kmaps, map);
 		dso__set_loaded(dso);
+
+		if (is_bpf_image(event->ksymbol.name)) {
+			dso->binary_type = DSO_BINARY_TYPE__BPF_IMAGE;
+			dso__set_long_name(dso, "", false);
+		}
 	}
 
 	sym = symbol__new(map->map_ip(map, map->start),

tools/perf/util/symbol.c

@@ -1544,6 +1544,7 @@ static bool dso__is_compatible_symtab_type(struct dso *dso, bool kmod,
 		return true;
 
 	case DSO_BINARY_TYPE__BPF_PROG_INFO:
+	case DSO_BINARY_TYPE__BPF_IMAGE:
 	case DSO_BINARY_TYPE__NOT_FOUND:
 	default:
 		return false;