Merge: perf annotate: Add annotation_options.disassembler_used

MR: https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-9/-/merge_requests/6748

# Merge Request Required Information
JIRA: https://issues.redhat.com/browse/RHEL-83785
## Summary of Changes

Signed-off-by: Jakub Brnak <jbrnak@redhat.com>

Approved-by: Michael Petlan <mpetlan@redhat.com>
Approved-by: ashelat <ashelat@redhat.com>
Approved-by: CKI KWF Bot <cki-ci-bot+kwf-gitlab-com@redhat.com>

Merged-by: Augusto Caringi <acaringi@redhat.com>

Author: caringi

tools/perf/Documentation/perf-config.txt

@@ -247,6 +247,19 @@ annotate.*::
 	These are in control of addresses, jump function, source code
 	in lines of assembly code from a specific program.
 
+	annotate.disassemblers::
+		Choose the disassembler to use: "objdump", "llvm",  "capstone",
+		if not specified it will first try, if available, the "llvm" one,
+		then, if it fails, "capstone", and finally the original "objdump"
+		based one.
+
+		Choosing a different one is useful when handling some feature that
+		is known to be best support at some point by one of the options,
+		to compare the output when in doubt about some bug, etc.
+
+		This can be a list, in order of preference, the first one that works
+		finishes the process.
+
 	annotate.addr2line::
 		addr2line binary to use for file names and line numbers.
 

tools/perf/util/annotate.c

@@ -2102,6 +2102,57 @@ int symbol__annotate2(struct map_symbol *ms, struct evsel *evsel,
 	return 0;
 }
 
+const char * const perf_disassembler__strs[] = {
+	[PERF_DISASM_UNKNOWN]  = "unknown",
+	[PERF_DISASM_LLVM]     = "llvm",
+	[PERF_DISASM_CAPSTONE] = "capstone",
+	[PERF_DISASM_OBJDUMP]  = "objdump",
+};
+
+
+static void annotation_options__add_disassembler(struct annotation_options *options,
+						 enum perf_disassembler dis)
+{
+	for (u8 i = 0; i < ARRAY_SIZE(options->disassemblers); i++) {
+		if (options->disassemblers[i] == dis) {
+			/* Disassembler is already present then don't add again. */
+			return;
+		}
+		if (options->disassemblers[i] == PERF_DISASM_UNKNOWN) {
+			/* Found a free slot. */
+			options->disassemblers[i] = dis;
+			return;
+		}
+	}
+	pr_err("Failed to add disassembler %d\n", dis);
+}
+
+static int annotation_options__add_disassemblers_str(struct annotation_options *options,
+						const char *str)
+{
+	while (str && *str != '\0') {
+		const char *comma = strchr(str, ',');
+		int len = comma ? comma - str : (int)strlen(str);
+		bool match = false;
+
+		for (u8 i = 0; i < ARRAY_SIZE(perf_disassembler__strs); i++) {
+			const char *dis_str = perf_disassembler__strs[i];
+
+			if (len == (int)strlen(dis_str) && !strncmp(str, dis_str, len)) {
+				annotation_options__add_disassembler(options, i);
+				match = true;
+				break;
+			}
+		}
+		if (!match) {
+			pr_err("Invalid disassembler '%.*s'\n", len, str);
+			return -1;
+		}
+		str = comma ? comma + 1 : NULL;
+	}
+	return 0;
+}
+
 static int annotation__config(const char *var, const char *value, void *data)
 {
 	struct annotation_options *opt = data;
@@ -2116,6 +2167,11 @@ static int annotation__config(const char *var, const char *value, void *data)
 			opt->offset_level = ANNOTATION__MAX_OFFSET_LEVEL;
 		else if (opt->offset_level < ANNOTATION__MIN_OFFSET_LEVEL)
 			opt->offset_level = ANNOTATION__MIN_OFFSET_LEVEL;
+	} else if (!strcmp(var, "annotate.disassemblers")) {
+		int err = annotation_options__add_disassemblers_str(opt, value);
+
+		if (err)
+			return err;
 	} else if (!strcmp(var, "annotate.hide_src_code")) {
 		opt->hide_src_code = perf_config_bool("hide_src_code", value);
 	} else if (!strcmp(var, "annotate.jump_arrows")) {
@@ -2181,9 +2237,25 @@ void annotation_options__exit(void)
 	zfree(&annotate_opts.objdump_path);
 }
 
+static void annotation_options__default_init_disassemblers(struct annotation_options *options)
+{
+	if (options->disassemblers[0] != PERF_DISASM_UNKNOWN) {
+		/* Already initialized. */
+		return;
+	}
+#ifdef HAVE_LIBLLVM_SUPPORT
+	annotation_options__add_disassembler(options, PERF_DISASM_LLVM);
+#endif
+#ifdef HAVE_LIBCAPSTONE_SUPPORT
+	annotation_options__add_disassembler(options, PERF_DISASM_CAPSTONE);
+#endif
+	annotation_options__add_disassembler(options, PERF_DISASM_OBJDUMP);
+}
+
 void annotation_config__init(void)
 {
 	perf_config(annotation__config, &annotate_opts);
+	annotation_options__default_init_disassemblers(&annotate_opts);
 }
 
 static unsigned int parse_percent_type(char *str1, char *str2)

tools/perf/util/annotate.h

@@ -34,6 +34,14 @@ struct annotated_data_type;
 #define ANNOTATION__BR_CNTR_WIDTH 30
 #define ANNOTATION_DUMMY_LEN	256
 
+enum perf_disassembler {
+	PERF_DISASM_UNKNOWN = 0,
+	PERF_DISASM_LLVM,
+	PERF_DISASM_CAPSTONE,
+	PERF_DISASM_OBJDUMP,
+};
+#define MAX_DISASSEMBLERS (PERF_DISASM_OBJDUMP + 1)
+
 struct annotation_options {
 	bool hide_src_code,
 	     use_offset,
@@ -49,6 +57,8 @@ struct annotation_options {
 	     annotate_src,
 	     full_addr;
 	u8   offset_level;
+	u8   disassemblers[MAX_DISASSEMBLERS];
+	u8   disassembler_used;
 	int  min_pcnt;
 	int  max_lines;
 	int  context;
@@ -128,6 +138,8 @@ struct disasm_line {
 	struct annotation_line	 al;
 };
 
+extern const char * const perf_disassembler__strs[];
+
 void annotation_line__add(struct annotation_line *al, struct list_head *head);
 
 static inline double annotation_data__percent(struct annotation_data *data,