From mboxrd@z Thu Jan 1 00:00:00 1970 From: Zenghui Yu Subject: [PATCH v1 3/5] perf tools arm64: Add support for get_cpuid() function Date: Wed, 12 Jun 2019 09:08:44 +0000 Message-ID: <1560330526-15468-4-git-send-email-yuzenghui@huawei.com> References: <1560330526-15468-1-git-send-email-yuzenghui@huawei.com> Mime-Version: 1.0 Content-Type: text/plain Return-path: In-Reply-To: <1560330526-15468-1-git-send-email-yuzenghui@huawei.com> Sender: linux-kernel-owner@vger.kernel.org To: linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org Cc: christoffer.dall@arm.com, marc.zyngier@arm.com, acme@redhat.com, peterz@infradead.org, mingo@redhat.com, ganapatrao.kulkarni@cavium.com, catalin.marinas@arm.com, will.deacon@arm.com, mark.rutland@arm.com, acme@kernel.org, alexander.shishkin@linux.intel.com, jolsa@redhat.com, namhyung@kernel.org, wanghaibin.wang@huawei.com, xiexiangyou@huawei.com, linuxarm@huawei.com, Zenghui Yu List-Id: linux-perf-users.vger.kernel.org The get_cpuid() function returns the MIDR string of the first CPU. Cc: Ganapatrao Kulkarni Cc: Arnaldo Carvalho de Melo Cc: Peter Zijlstra Cc: Ingo Molnar Cc: Catalin Marinas Cc: Will Deacon Cc: Mark Rutland Signed-off-by: Zenghui Yu --- When recording, perf will write host's cpuid (through get_cpuid()) into perf.data.guest file: __cmd_record record__finish_output perf_session__write_header perf_header__adds_write do_write_feat (type == HEADER_CPUID) write_cpuid When reporting, perf will read cpuid from perf.data.guest file: read_events perf_session__new perf_session__open perf_session__read_header perf_header__process_sections perf_file_section__process process_cpuid I'm not familiar with ARM ID register usage, and how does perf code make use of get_cpuid() function. If we left get_cpuid() unimplemented on arm64 (we have a default implementation in tools/perf/util/header.c), 'perf kvm stat report' will failed with following error: "Failed to look up CPU type" I will read the code further, and any comments or suggestions from both sides (arm64 & perf) will be appreciated. --- tools/perf/arch/arm64/util/header.c | 74 +++++++++++++++++++++++-------------- 1 file changed, 47 insertions(+), 27 deletions(-) diff --git a/tools/perf/arch/arm64/util/header.c b/tools/perf/arch/arm64/util/header.c index 534cd25..5c17b86 100644 --- a/tools/perf/arch/arm64/util/header.c +++ b/tools/perf/arch/arm64/util/header.c @@ -9,17 +9,56 @@ #define MIDR_VARIANT_SHIFT 20 #define MIDR_VARIANT_MASK (0xf << MIDR_VARIANT_SHIFT) -char *get_cpuid_str(struct perf_pmu *pmu) +/* Return value of midr_el1 if success, else return 0. */ +static int read_midr_el1(char *buf, int cpu_nr) { - char *buf = NULL; char path[PATH_MAX]; const char *sysfs = sysfs__mountpoint(); + u64 midr = 0; + FILE *file; + + if (!sysfs) + return 0; + + scnprintf(path, PATH_MAX, "%s/devices/system/cpu/cpu%d"MIDR, + sysfs, cpu_nr); + + file = fopen(path, "r"); + if (!file) { + pr_debug("fopen failed for file %s\n", path); + return 0; + } + + if (!fgets(buf, MIDR_SIZE, file)) { + fclose(file); + return 0; + } + fclose(file); + + /* Ignore/clear Variant[23:20] and Revision[3:0] of MIDR */ + midr = strtoul(buf, NULL, 16); + midr &= (~(MIDR_VARIANT_MASK | MIDR_REVISION_MASK)); + scnprintf(buf, MIDR_SIZE, "0x%016lx", midr); + + return midr; +} + +int get_cpuid(char *buffer, size_t sz __maybe_unused) +{ + if (read_midr_el1(buffer, 0)) + return 0; + + return -1; +} + +char *get_cpuid_str(struct perf_pmu *pmu) +{ + char *buf = NULL; int cpu; u64 midr = 0; struct cpu_map *cpus; - FILE *file; - if (!sysfs || !pmu || !pmu->cpus) + if (!pmu || !pmu->cpus) return NULL; buf = malloc(MIDR_SIZE); @@ -29,29 +68,10 @@ char *get_cpuid_str(struct perf_pmu *pmu) /* 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_debug("fopen failed for file %s\n", path); - continue; - } - - if (!fgets(buf, MIDR_SIZE, file)) { - fclose(file); - continue; - } - fclose(file); - - /* Ignore/clear Variant[23:20] and - * Revision[3:0] of MIDR - */ - midr = strtoul(buf, NULL, 16); - midr &= (~(MIDR_VARIANT_MASK | MIDR_REVISION_MASK)); - scnprintf(buf, MIDR_SIZE, "0x%016lx", midr); - /* got midr break loop */ - break; + midr = read_midr_el1(buf, cpus->map[cpu]); + if (midr) + /* got midr break loop */ + break; } if (!midr) { -- 1.8.3.1