perf arm64 header: Use cpu argument in get_cpuid

Use the cpu to read the MIDR file requested. If the "any" value (-1) is
passed that keep the behavior of returning the first MIDR file that can
be read.

Reviewed-by: James Clark <[e-mail]>
Signed-off-by: Ian Rogers <[e-mail]>
Tested-by: Xu Yang <[e-mail]>
Cc: Adrian Hunter <[e-mail]>
Cc: Albert Ou <[e-mail]>
Cc: Alexander Shishkin <[e-mail]>
Cc: Alexandre Ghiti <[e-mail]>
Cc: Athira Rajeev <[e-mail]>
Cc: Ben Zong-You Xie <[e-mail]>
Cc: Benjamin Gray <[e-mail]>
Cc: Bibo Mao <[e-mail]>
Cc: Clément Le Goffic <[e-mail]>
Cc: Dima Kogan <[e-mail]>
Cc: Dr. David Alan Gilbert <[e-mail]>
Cc: Huacai Chen <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: John Garry <[e-mail]>
Cc: Kan Liang <[e-mail]>
Cc: Leo Yan <[e-mail]>
Cc: Mark Rutland <[e-mail]>
Cc: Masami Hiramatsu <[e-mail]>
Cc: Mike Leach <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: Palmer Dabbelt <[e-mail]>
Cc: Paul Walmsley <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: Ravi Bangoria <[e-mail]>
Cc: Sandipan Das <[e-mail]>
Cc: Will Deacon <[e-mail]>
Cc: Yicong Yang <[e-mail]>
Cc: [e-mail]
Cc: [e-mail]
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/arch/arm64/util/header.c

···
 #define MIDR_REVISION_MASK      GENMASK(3, 0)
 #define MIDR_VARIANT_MASK	GENMASK(23, 20)
 
-static int _get_cpuid(char *buf, size_t sz, struct perf_cpu_map *cpus)
+static int _get_cpuid(char *buf, size_t sz, struct perf_cpu cpu)
 {
+	char path[PATH_MAX];
+	FILE *file;
 	const char *sysfs = sysfs__mountpoint();
-	struct perf_cpu cpu;
-	int idx, ret = EINVAL;
 
+	assert(cpu.cpu != -1);
 	if (!sysfs || sz < MIDR_SIZE)
 		return EINVAL;
 
-	perf_cpu_map__for_each_cpu(cpu, idx, cpus) {
-		char path[PATH_MAX];
-		FILE *file;
+	scnprintf(path, PATH_MAX, "%s/devices/system/cpu/cpu%d" MIDR, sysfs, cpu.cpu);
 
-		scnprintf(path, PATH_MAX, "%s/devices/system/cpu/cpu%d" MIDR,
-			  sysfs, cpu.cpu);
-
-		file = fopen(path, "r");
-		if (!file) {
-			pr_debug("fopen failed for file %s\n", path);
-			continue;
-		}
-
-		if (!fgets(buf, MIDR_SIZE, file)) {
-			fclose(file);
-			continue;
-		}
-		fclose(file);
-
-		/* got midr break loop */
-		ret = 0;
-		break;
+	file = fopen(path, "r");
+	if (!file) {
+		pr_debug("fopen failed for file %s\n", path);
+		return EINVAL;
 	}
 
-	return ret;
+	if (!fgets(buf, MIDR_SIZE, file)) {
+		pr_debug("Failed to read file %s\n", path);
+		fclose(file);
+		return EINVAL;
+	}
+	fclose(file);
+	return 0;
 }
 
-int get_cpuid(char *buf, size_t sz, struct perf_cpu cpu __maybe_unused)
+int get_cpuid(char *buf, size_t sz, struct perf_cpu cpu)
 {
-	struct perf_cpu_map *cpus = perf_cpu_map__new_online_cpus();
-	int ret;
+	struct perf_cpu_map *cpus;
+	int idx;
 
+	if (cpu.cpu != -1)
+		return _get_cpuid(buf, sz, cpu);
+
+	cpus = perf_cpu_map__new_online_cpus();
 	if (!cpus)
 		return EINVAL;
 
-	ret = _get_cpuid(buf, sz, cpus);
+	perf_cpu_map__for_each_cpu(cpu, idx, cpus) {
+		int ret = _get_cpuid(buf, sz, cpu);
 
-	perf_cpu_map__put(cpus);
-
-	return ret;
+		if (ret == 0)
+			return 0;
+	}
+	return EINVAL;
 }
 
 char *get_cpuid_str(struct perf_pmu *pmu)
···
 		return NULL;
 
 	/* read midr from list of cpus mapped to this pmu */
-	res = _get_cpuid(buf, MIDR_SIZE, pmu->cpus);
+	res = get_cpuid(buf, MIDR_SIZE, perf_cpu_map__min(pmu->cpus));
 	if (res) {
 		pr_err("failed to get cpuid string for PMU %s\n", pmu->name);
 		free(buf);

tools/perf/util/header.h

···
 #include <linux/types.h>
 #include "env.h"
 #include "pmu.h"
+#include <perf/cpumap.h>
 
 enum {
 	HEADER_RESERVED		= 0,	/* always cleared */