perf env: Cache the arch specific strerrno function in perf_env__arch_strerrno()

So that we don't have to go thru the series of strcmp(arch) calls for
each id -> string translation.
Reviewed-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Laight <David.Laight@ACULAB.COM>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/lkml/20231201203046.486596-3-acme@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/trace/beauty/arch_errno_names.sh

@@ -57,13 +57,13 @@ create_arch_errno_table_func()
 	archlist="$1"
 	default="$2"
 
-	printf 'const char *arch_syscalls__strerrno(const char *arch, int err)\n'
+	printf 'arch_syscalls__strerrno_t *arch_syscalls__strerrno_function(const char *arch)\n'
 	printf '{\n'
 	for arch in $archlist; do
 		printf '\tif (!strcmp(arch, "%s"))\n' $(arch_string "$arch")
-		printf '\t\treturn errno_to_name__%s(err);\n' $(arch_string "$arch")
+		printf '\t\treturn errno_to_name__%s;\n' $(arch_string "$arch")
 	done
-	printf '\treturn errno_to_name__%s(err);\n' $(arch_string "$default")
+	printf '\treturn errno_to_name__%s;\n' $(arch_string "$default")
 	printf '}\n'
 }
 

tools/perf/trace/beauty/beauty.h

@@ -251,6 +251,4 @@ size_t open__scnprintf_flags(unsigned long flags, char *bf, size_t size, bool sh
 void syscall_arg__set_ret_scnprintf(struct syscall_arg *arg,
 				    size_t (*ret_scnprintf)(char *bf, size_t size, struct syscall_arg *arg));
 
-const char *arch_syscalls__strerrno(const char *arch, int err);
-
 #endif /* _PERF_TRACE_BEAUTY_H */

tools/perf/util/env.c

@@ -458,8 +458,10 @@ const char *perf_env__arch(struct perf_env *env)
 const char *perf_env__arch_strerrno(struct perf_env *env __maybe_unused, int err __maybe_unused)
 {
 #if defined(HAVE_SYSCALL_TABLE_SUPPORT) && defined(HAVE_LIBTRACEEVENT)
-	const char *arch_name = perf_env__arch(env);
-	return arch_syscalls__strerrno(arch_name, err);
+	if (env->arch_strerrno == NULL)
+		env->arch_strerrno = arch_syscalls__strerrno_function(perf_env__arch(env));
+
+	return env->arch_strerrno ? env->arch_strerrno(err) : "no arch specific strerrno function";
 #else
 	return "!(HAVE_SYSCALL_TABLE_SUPPORT && HAVE_LIBTRACEEVENT)";
 #endif

tools/perf/util/env.h

@@ -53,6 +53,10 @@ struct pmu_caps {
 	char            *pmu_name;
 };
 
+typedef const char *(arch_syscalls__strerrno_t)(int err);
+
+arch_syscalls__strerrno_t *arch_syscalls__strerrno_function(const char *arch);
+
 struct perf_env {
 	char			*hostname;
 	char			*os_release;
@@ -135,6 +139,7 @@ struct perf_env {
 		 */
 		bool	enabled;
 	} clock;
+	arch_syscalls__strerrno_t *arch_strerrno;
 };
 
 enum perf_compress_type {