1 files changed, 105 insertions, 0 deletions
diff --git a/lib/trace-cmd/trace-perf.c b/lib/trace-cmd/trace-perf.c
new file mode 100644
index 00000000..a10da55d
--- /dev/null
+++ b/lib/trace-cmd/trace-perf.c
@@ -0,0 +1,105 @@
+// SPDX-License-Identifier: LGPL-2.1
+/*
+ * Copyright (C) 2021, VMware, Tzvetomir Stoyanov <tz.stoyanov@gmail.com>
+ *
+ */
+#include <unistd.h>
+#include <sys/syscall.h>
+#include <sys/mman.h>
+
+#include "trace-cmd-private.h"
+
+static void default_perf_init_pe(struct perf_event_attr *pe)
+{
+	pe->type = PERF_TYPE_SOFTWARE;
+	pe->sample_type = PERF_SAMPLE_CPU;
+	pe->size = sizeof(struct perf_event_attr);
+	pe->config = PERF_COUNT_HW_CPU_CYCLES;
+	pe->disabled = 1;
+	pe->exclude_kernel = 1;
+	pe->freq = 1;
+	pe->sample_freq = 1000;
+	pe->inherit = 1;
+	pe->mmap = 1;
+	pe->comm = 1;
+	pe->task = 1;
+	pe->precise_ip = 1;
+	pe->sample_id_all = 1;
+	pe->read_format = PERF_FORMAT_ID |
+			PERF_FORMAT_TOTAL_TIME_ENABLED |
+			PERF_FORMAT_TOTAL_TIME_RUNNING;
+}
+
+/**
+ * trace_perf_init - Initialize perf context
+ *
+ * @perf: structure, representing perf context, that will be initialized.
+ * @pages: Number of perf memory mapped pages.
+ * @cpu: CPU number, associated with this perf context.
+ * @pid: PID, associated with this perf context.
+ *
+ * The perf context in initialized with default values. The caller can set
+ * custom perf parameters in perf->pe, before calling trace_perf_open() API.
+ *
+ * Returns 0 on success, or -1 in case of an error.
+ *
+ */
+int __hidden trace_perf_init(struct trace_perf *perf, int pages, int cpu, int pid)
+{
+	if (!perf)
+		return -1;
+
+	memset(perf, 0, sizeof(struct trace_perf));
+	default_perf_init_pe(&perf->pe);
+	perf->cpu = cpu;
+	perf->pages = pages;
+	perf->pid = pid;
+	perf->fd = -1;
+
+	return 0;
+}
+
+/**
+ * trace_perf_close - Close perf session
+ *
+ * @perf: structure, representing context of a running perf session, opened
+ *	  with trace_perf_open()
+ *
+ */
+void __hidden trace_perf_close(struct trace_perf *perf)
+{
+	if (perf->fd >= 0)
+		close(perf->fd);
+	perf->fd = -1;
+	if (perf->mmap && perf->mmap != MAP_FAILED)
+		munmap(perf->mmap, (perf->pages + 1) * getpagesize());
+	perf->mmap = NULL;
+}
+
+/**
+ * trace_perf_open - Open perf session
+ *
+ * @perf: structure, representing perf context that will be opened. It must be
+ *	  initialized with trace_perf_init().
+ *
+ * Returns 0 on success, or -1 in case of an error. In case of success, the
+ * session must be closed with trace_perf_close()
+ */
+int __hidden trace_perf_open(struct trace_perf *perf)
+{
+	perf->fd = syscall(__NR_perf_event_open, &perf->pe, perf->pid, perf->cpu, -1, 0);
+	if (perf->fd < 0)
+		return -1;
+	fcntl(perf->fd, F_SETFL, O_NONBLOCK);
+
+	perf->mmap = mmap(NULL, (perf->pages + 1) * getpagesize(),
+			  PROT_READ | PROT_WRITE, MAP_SHARED, perf->fd, 0);
+	if (perf->mmap == MAP_FAILED)
+		goto error;
+
+	return 0;
+
+error:
+	trace_perf_close(perf);
+	return -1;
+}