[PATCH v8 13/17] perf env: Refactor perf_env__arch_strerrno

[Ian Rogers <irogers@google.com>]

perf_env__arch_strerrno is only available with libtraceevent so hide
the declaration if no libtraceevent.

The previous approach maps an architecture string to a function
pointer to a function that takes an int errno values and returns a
string. The new approach takes an e_machine and an errno value and
returns a string.

As the only call site is in builtin-trace.c, the e_machine is already
present and potentially more specific than the perf_env arch string
that is a single global value.

The major complication in this approach is having the shell script
that generates the C code map a linux directory name to the matching
ELF machine constants.

Signed-off-by: Ian Rogers <irogers@google.com>
---
 tools/perf/builtin-trace.c                  |  5 ++-
 tools/perf/trace/beauty/arch_errno_names.sh | 40 ++++++++++++++++++---
 tools/perf/util/env.c                       | 13 +++----
 tools/perf/util/env.h                       |  7 ++--
 4 files changed, 44 insertions(+), 21 deletions(-)

diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
index e58c49d047a2..d1f21b5e7c98 100644
--- a/tools/perf/builtin-trace.c
+++ b/tools/perf/builtin-trace.c
@@ -3008,9 +3008,8 @@ static int trace__sys_exit(struct trace *trace, struct evsel *evsel,
 	} else if (ret < 0) {
 errno_print: {
 		char bf[STRERR_BUFSIZE];
-		struct perf_env *env = evsel__env(evsel) ?: &trace->host_env;
 		const char *emsg = str_error_r(-ret, bf, sizeof(bf));
-		const char *e = perf_env__arch_strerrno(env, err);
+		const char *e = perf_env__arch_strerrno(e_machine, err);
 
 		fprintf(trace->output, "-1 %s (%s)", e, emsg);
 	}
@@ -4890,7 +4889,7 @@ static size_t syscall__dump_stats(struct trace *trace, int e_machine, FILE *fp,
 
 				for (e = 0; e < stats->max_errno; ++e) {
 					if (stats->errnos[e] != 0)
-						fprintf(fp, "\t\t\t\t%s: %d\n", perf_env__arch_strerrno(trace->host->env, e + 1), stats->errnos[e]);
+						fprintf(fp, "\t\t\t\t%s: %d\n", perf_env__arch_strerrno(e_machine, e + 1), stats->errnos[e]);
 				}
 			}
 			lines++;
diff --git a/tools/perf/trace/beauty/arch_errno_names.sh b/tools/perf/trace/beauty/arch_errno_names.sh
index b22890b8d272..89b742927168 100755
--- a/tools/perf/trace/beauty/arch_errno_names.sh
+++ b/tools/perf/trace/beauty/arch_errno_names.sh
@@ -52,21 +52,49 @@ process_arch()
 		|IFS=, create_errno_lookup_func "$arch"
 }
 
+arch_to_e_machine()
+{
+	case "$1" in
+	alpha)      printf '\tcase EM_ALPHA:\n' ;;
+	arc)        printf '\tcase EM_ARC:\n' ;;
+	arm)        printf '\tcase EM_ARM:\n' ;;
+	arm64)      printf '\tcase EM_AARCH64:\n' ;;
+	csky)       printf '\tcase EM_CSKY:\n' ;;
+	hexagon)    printf '\tcase EM_HEXAGON:\n' ;;
+	loongarch)  printf '\tcase EM_LOONGARCH:\n' ;;
+	microblaze) printf '\tcase EM_MICROBLAZE:\n' ;;
+	mips)       printf '\tcase EM_MIPS:\n' ;;
+	parisc)     printf '\tcase EM_PARISC:\n' ;;
+	powerpc)    printf '\tcase EM_PPC:\n\tcase EM_PPC64:\n' ;;
+	riscv)      printf '\tcase EM_RISCV:\n' ;;
+	s390)       printf '\tcase EM_S390:\n' ;;
+	sh)         printf '\tcase EM_SH:\n' ;;
+	sparc)      printf '\tcase EM_SPARC:\n\tcase EM_SPARCV9:\n' ;;
+	x86)        printf '\tcase EM_386:\n\tcase EM_X86_64:\n' ;;
+	xtensa)     printf '\tcase EM_XTENSA:\n' ;;
+	esac
+}
+
 create_arch_errno_table_func()
 {
 	archlist="$1"
 	default="$2"
 
-	printf 'static arch_syscalls__strerrno_t *\n'
-	printf 'arch_syscalls__strerrno_function(const char *arch)\n'
+	printf 'static const char *\n'
+	printf 'arch_syscalls__strerrno(uint16_t e_machine, int err)\n'
 	printf '{\n'
+	printf '\tswitch (e_machine) {\n'
 	for arch in $archlist; do
 		arch_str=$(arch_string "$arch")
-		printf '\tif (!strcmp(arch, "%s"))\n' "$arch_str"
-		printf '\t\treturn errno_to_name__%s;\n' "$arch_str"
+		ems=$(arch_to_e_machine "$arch_str")
+		if [ -n "$ems" ]; then
+			printf '%s\n' "$ems"
+			printf '\t\treturn errno_to_name__%s(err);\n' "$arch_str"
+		fi
 	done
 	arch_str=$(arch_string "$default")
-	printf '\treturn errno_to_name__%s;\n' "$arch_str"
+	printf '\tdefault:\n\t\treturn errno_to_name__%s(err);\n' "$arch_str"
+	printf '\t}\n'
 	printf '}\n'
 }
 
@@ -74,6 +102,8 @@ cat <<EoHEADER
 /* SPDX-License-Identifier: GPL-2.0 */
 
 #include <string.h>
+#include <stdint.h>
+#include <elf.h>
 
 EoHEADER
 
diff --git a/tools/perf/util/env.c b/tools/perf/util/env.c
index 4ff4caab3b32..97f4aa1131a1 100644
--- a/tools/perf/util/env.c
+++ b/tools/perf/util/env.c
@@ -786,17 +786,12 @@ const char *perf_env__arch(struct perf_env *env)
 #include "trace/beauty/arch_errno_names.c"
 #endif
 
-const char *perf_env__arch_strerrno(struct perf_env *env __maybe_unused, int err __maybe_unused)
-{
 #if defined(HAVE_LIBTRACEEVENT)
-	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_LIBTRACEEVENT";
-#endif
+const char *perf_env__arch_strerrno(uint16_t e_machine, int err)
+{
+	return arch_syscalls__strerrno(e_machine, err);
 }
+#endif
 
 const char *perf_env__cpuid(struct perf_env *env)
 {
diff --git a/tools/perf/util/env.h b/tools/perf/util/env.h
index 7151a9138e3f..68dead1b36a6 100644
--- a/tools/perf/util/env.h
+++ b/tools/perf/util/env.h
@@ -67,8 +67,6 @@ struct cpu_domain_map {
 	struct domain_info	**domains;
 };
 
-typedef const char *(arch_syscalls__strerrno_t)(int err);
-
 struct perf_env {
 	char			*hostname;
 	char			*os_release;
@@ -158,7 +156,6 @@ struct perf_env {
 		 */
 		bool	enabled;
 	} clock;
-	arch_syscalls__strerrno_t *arch_strerrno;
 };
 
 enum perf_compress_type {
@@ -190,7 +187,9 @@ void cpu_cache_level__free(struct cpu_cache_level *cache);
 uint16_t perf_env__e_machine_nocache(struct perf_env *env, uint32_t *e_flags);
 uint16_t perf_env__e_machine(struct perf_env *env, uint32_t *e_flags);
 const char *perf_env__arch(struct perf_env *env);
-const char *perf_env__arch_strerrno(struct perf_env *env, int err);
+#if defined(HAVE_LIBTRACEEVENT)
+const char *perf_env__arch_strerrno(uint16_t e_machine, int err);
+#endif
 const char *perf_env__cpuid(struct perf_env *env);
 const char *perf_env__raw_arch(struct perf_env *env);
 int perf_env__nr_cpus_avail(struct perf_env *env);
-- 
2.54.0.545.g6539524ca2-goog