[PATCH v5 2/4] perf tools arm64: Add support for get_cpuid_str function.
From: Will Deacon <hidden>
Date: 2017-08-23 10:18:08
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On Wed, Aug 16, 2017 at 12:40:46PM +0530, Ganapatrao Kulkarni wrote:
quoted hunk ↗ jump to hunk
function get_cpuid_str returns MIDR string of the first online cpu from the range of cpus associated with the pmu core device. Signed-off-by: Ganapatrao Kulkarni <redacted> --- tools/perf/arch/arm64/util/Build | 1 + tools/perf/arch/arm64/util/header.c | 61 +++++++++++++++++++++++++++++++++++++ 2 files changed, 62 insertions(+) create mode 100644 tools/perf/arch/arm64/util/header.cdiff --git a/tools/perf/arch/arm64/util/Build b/tools/perf/arch/arm64/util/Build index cef6fb3..b1ab72d 100644 --- a/tools/perf/arch/arm64/util/Build +++ b/tools/perf/arch/arm64/util/Build@@ -1,3 +1,4 @@ +libperf-y += header.o libperf-$(CONFIG_DWARF) += dwarf-regs.o libperf-$(CONFIG_LOCAL_LIBUNWIND) += unwind-libunwind.odiff --git a/tools/perf/arch/arm64/util/header.c b/tools/perf/arch/arm64/util/header.c new file mode 100644 index 0000000..713ef17 --- /dev/null +++ b/tools/perf/arch/arm64/util/header.c@@ -0,0 +1,61 @@ +#include <stdio.h> +#include <stdlib.h> +#include <api/fs/fs.h> +#include "header.h" + +#define MIDR "/regs/identification/midr_el1" +#define MIDR_SIZE 128
Why is this so big?
+char *get_cpuid_str(struct perf_pmu *pmu)
+{
+ char *buf = NULL;
+ char *temp = NULL;
+ char path[PATH_MAX];
+ const char *sysfs = sysfs__mountpoint();
+ int cpu;
+ unsigned long long midr = 0;
+ struct cpu_map *cpus;
+ FILE *file;
+
+ if (!sysfs || !pmu->cpus)
+ return NULL;
+
+ buf = malloc(MIDR_SIZE);
+ if (!buf)
+ return NULL;
+
+ /* read midr from list of cpus mapped to this pmu */
+ cpus = cpu_map__get(pmu->cpus);
+ for (cpu = 0; cpu < cpus->nr; cpu++) {
+ scnprintf(path, PATH_MAX, "%s/devices/system/cpu/cpu%d"MIDR,
+ sysfs, cpus->map[cpu]);
+
+ file = fopen(path, "r");
+ if (!file) {
+ pr_err("fopen failed for file %s\n", path);pr_debug instead? It's not fatal if a CPU is hotplugged off and you can't read its midr.
+ continue; + } + + temp = fgets(buf, MIDR_SIZE, file); + if (!temp) + continue;
Do you actually need a temporary variable for this?
+ fclose(file); + + /* Ignore/clear Variant[23:20] and + * Revision[3:0] of MIDR + */ + midr = strtoll(buf, NULL, 16); + midr &= (~(0xf << 20 | 0xf));
If midr really needs to be unsigned long long (u64 might be better), then you need to fix these immediates to have a ULL suffix. Can you use the GENMASK_ULL macro to generate the MIDR mask, or is that not available here?
+ scnprintf(buf, MIDR_SIZE, "0x%016llx", midr);
+ /* got midr break loop */
+ break;
+ }
+
+ if (!midr) {
+ free(buf);
+ buf = NULL;If you want the pr_err, here would seem more appropriate because at this point we've actually failed. Will