[PATCH v6 1/3] perf tools riscv: Add support for get_cpuid_str function

[Nikita Shubin]

From: Nikita Shubin <n.shubin at yadro.com>

The get_cpuid_str function returns the string that
contains values of MVENDORID, MARCHID and MIMPID in
hex format separated by coma.

The values themselves are taken from first cpu entry
in "/proc/cpuid" that contains "mvendorid", "marchid"
and "mimpid".

Signed-off-by: Nikita Shubin <n.shubin at yadro.com>
Tested-by: Kautuk Consul <kconsul at ventanamicro.com>
---
 tools/perf/arch/riscv/util/Build    |   1 +
 tools/perf/arch/riscv/util/header.c | 104 ++++++++++++++++++++++++++++
 2 files changed, 105 insertions(+)
 create mode 100644 tools/perf/arch/riscv/util/header.c

diff --git a/tools/perf/arch/riscv/util/Build b/tools/perf/arch/riscv/util/Build
index 7d3050134ae0..603dbb5ae4dc 100644
--- a/tools/perf/arch/riscv/util/Build
+++ b/tools/perf/arch/riscv/util/Build
@@ -1,4 +1,5 @@
 perf-y += perf_regs.o
+perf-y += header.o
 
 perf-$(CONFIG_DWARF) += dwarf-regs.o
 perf-$(CONFIG_LIBDW_DWARF_UNWIND) += unwind-libdw.o
diff --git a/tools/perf/arch/riscv/util/header.c b/tools/perf/arch/riscv/util/header.c
new file mode 100644
index 000000000000..4a41856938a8
--- /dev/null
+++ b/tools/perf/arch/riscv/util/header.c
@@ -0,0 +1,104 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Implementation of get_cpuid().
+ *
+ * Author: Nikita Shubin <n.shubin at yadro.com>
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <api/fs/fs.h>
+#include <errno.h>
+#include "../../util/debug.h"
+#include "../../util/header.h"
+
+#define CPUINFO_MVEN	"mvendorid"
+#define CPUINFO_MARCH	"marchid"
+#define CPUINFO_MIMP	"mimpid"
+#define CPUINFO		"/proc/cpuinfo"
+
+static char *_get_field(const char *line)
+{
+	char *line2, *nl;
+
+	line2 = strrchr(line, ' ');
+	if (!line2)
+		return NULL;
+
+	line2++;
+	nl = strrchr(line, '\n');
+	if (!nl)
+		return NULL;
+
+	return strndup(line2, nl - line2);
+}
+
+static char *_get_cpuid(void)
+{
+	char *line = NULL;
+	char *mvendorid = NULL;
+	char *marchid = NULL;
+	char *mimpid = NULL;
+	char *cpuid = NULL;
+	int read;
+	unsigned long line_sz;
+	FILE *cpuinfo;
+
+	cpuinfo = fopen(CPUINFO, "r");
+	if (cpuinfo == NULL)
+		return cpuid;
+
+	while ((read = getline(&line, &line_sz, cpuinfo)) != -1) {
+		if (!strncmp(line, CPUINFO_MVEN, strlen(CPUINFO_MVEN))) {
+			mvendorid = _get_field(line);
+			if (!mvendorid)
+				goto free;
+		} else if (!strncmp(line, CPUINFO_MARCH, strlen(CPUINFO_MARCH))) {
+			marchid = _get_field(line);
+			if (!marchid)
+				goto free;
+		} else if (!strncmp(line, CPUINFO_MIMP, strlen(CPUINFO_MIMP))) {
+			mimpid = _get_field(line);
+			if (!mimpid)
+				goto free;
+
+			break;
+		}
+	}
+
+	if (!mvendorid || !marchid || !mimpid)
+		goto free;
+
+	if (asprintf(&cpuid, "%s-%s-%s", mvendorid, marchid, mimpid) < 0)
+		cpuid = NULL;
+
+free:
+	fclose(cpuinfo);
+	free(mvendorid);
+	free(marchid);
+	free(mimpid);
+
+	return cpuid;
+}
+
+int get_cpuid(char *buffer, size_t sz)
+{
+	char *cpuid = _get_cpuid();
+	int ret = 0;
+
+	if (sz < strlen(cpuid)) {
+		ret = -EINVAL;
+		goto free;
+	}
+
+	scnprintf(buffer, sz, "%s", cpuid);
+free:
+	free(cpuid);
+	return ret;
+}
+
+char *
+get_cpuid_str(struct perf_pmu *pmu __maybe_unused)
+{
+	return _get_cpuid();
+}
-- 
2.35.1